Add driver for the Intel DisplayPort RX FPGA IP

Signed-off-by: Paweł Anikiel <panik...@google.com>
---
 drivers/media/platform/intel/Kconfig      |   12 +
 drivers/media/platform/intel/Makefile     |    1 +
 drivers/media/platform/intel/intel-dprx.c | 2176 +++++++++++++++++++++
 3 files changed, 2189 insertions(+)
 create mode 100644 drivers/media/platform/intel/intel-dprx.c

diff --git a/drivers/media/platform/intel/Kconfig 
b/drivers/media/platform/intel/Kconfig
index 724e80a9086d..eafcd47cce68 100644
--- a/drivers/media/platform/intel/Kconfig
+++ b/drivers/media/platform/intel/Kconfig
@@ -12,3 +12,15 @@ config VIDEO_PXA27x
        select V4L2_FWNODE
        help
          This is a v4l2 driver for the PXA27x Quick Capture Interface
+
+config VIDEO_INTEL_DPRX
+       tristate "Intel DisplayPort RX IP driver"
+       depends on V4L_PLATFORM_DRIVERS
+       depends on VIDEO_DEV
+       select V4L2_FWNODE
+       select CRC_DP
+       help
+         v4l2 subdev driver for Intel Displayport receiver FPGA IP.
+         It is a part of the DisplayPort Intel FPGA IP Core.
+         It implements a DisplayPort 1.4 receiver capable of HBR3
+         video capture and Multi-Stream Transport.
diff --git a/drivers/media/platform/intel/Makefile 
b/drivers/media/platform/intel/Makefile
index 7e8889cbd2df..f571399f5aa8 100644
--- a/drivers/media/platform/intel/Makefile
+++ b/drivers/media/platform/intel/Makefile
@@ -1,2 +1,3 @@
 # SPDX-License-Identifier: GPL-2.0-only
 obj-$(CONFIG_VIDEO_PXA27x) += pxa_camera.o
+obj-$(CONFIG_VIDEO_INTEL_DPRX) += intel-dprx.o
diff --git a/drivers/media/platform/intel/intel-dprx.c 
b/drivers/media/platform/intel/intel-dprx.c
new file mode 100644
index 000000000000..d0c60e29e51d
--- /dev/null
+++ b/drivers/media/platform/intel/intel-dprx.c
@@ -0,0 +1,2176 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright 2023-2024 Google LLC.
+ * Author: Paweł Anikiel <panik...@google.com>
+ */
+
+#include <linux/crc-dp.h>
+#include <linux/delay.h>
+#include <linux/interrupt.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <media/v4l2-dv-timings.h>
+#include <media/v4l2-subdev.h>
+#include <drm/display/drm_dp.h>
+#include <drm/display/drm_dp_mst.h>
+
+#define DPRX_MAX_EDID_BLOCKS   4
+
+/* DPRX registers */
+
+#define DPRX_RX_CONTROL                                0x000
+#define DPRX_RX_CONTROL_LINK_RATE_SHIFT                16
+#define DPRX_RX_CONTROL_LINK_RATE_MASK         0xff
+#define DPRX_RX_CONTROL_RECONFIG_LINKRATE      13
+#define DPRX_RX_CONTROL_TP_SHIFT               8
+#define DPRX_RX_CONTROL_TP_MASK                        0x7
+#define DPRX_RX_CONTROL_SCRAMBLER_DISABLE      7
+#define DPRX_RX_CONTROL_CHANNEL_CODING_SHIFT   5
+#define DPRX_RX_CONTROL_CHANNEL_CODING_8B10B   0x1
+#define DPRX_RX_CONTROL_LANE_COUNT_SHIFT       0
+#define DPRX_RX_CONTROL_LANE_COUNT_MASK                0x1f
+
+#define DPRX_RX_STATUS                         0x001
+#define DPRX_RX_STATUS_INTERLANE_ALIGN         8
+#define DPRX_RX_STATUS_SYM_LOCK_SHIFT          4
+#define DPRX_RX_STATUS_SYM_LOCK(i)             (4 + i)
+#define DPRX_RX_STATUS_CR_LOCK_SHIFT           0
+#define DPRX_RX_STATUS_CR_LOCK(i)              (0 + i)
+
+#define DPRX_MSA_HTOTAL(i)                     (0x022 + 0x20 * (i))
+#define DPRX_MSA_VTOTAL(i)                     (0x023 + 0x20 * (i))
+#define DPRX_MSA_HSP(i)                                (0x024 + 0x20 * (i))
+#define DPRX_MSA_HSW(i)                                (0x025 + 0x20 * (i))
+#define DPRX_MSA_HSTART(i)                     (0x026 + 0x20 * (i))
+#define DPRX_MSA_VSTART(i)                     (0x027 + 0x20 * (i))
+#define DPRX_MSA_VSP(i)                                (0x028 + 0x20 * (i))
+#define DPRX_MSA_VSW(i)                                (0x029 + 0x20 * (i))
+#define DPRX_MSA_HWIDTH(i)                     (0x02a + 0x20 * (i))
+#define DPRX_MSA_VHEIGHT(i)                    (0x02b + 0x20 * (i))
+#define DPRX_VBID(i)                           (0x02f + 0x20 * (i))
+#define DPRX_VBID_MSA_LOCK                     7
+
+#define DPRX_MST_CONTROL1                      0x0a0
+#define DPRX_MST_CONTROL1_VCPTAB_UPD_FORCE     31
+#define DPRX_MST_CONTROL1_VCPTAB_UPD_REQ       30
+#define DPRX_MST_CONTROL1_VCP_ID_SHIFT(i)      (4 + 4 * (i))
+#define DPRX_MST_CONTROL1_VCP_IDS_SHIFT                4
+#define DPRX_MST_CONTROL1_VCP_IDS_MASK         0xffff
+#define DPRX_MST_CONTROL1_MST_EN               0
+
+#define DPRX_MST_STATUS1                       0x0a1
+#define DPRX_MST_STATUS1_VCPTAB_ACT_ACK                30
+
+#define DPRX_MST_VCPTAB(i)                     (0x0a2 + i)
+
+#define DPRX_AUX_CONTROL                       0x100
+#define DPRX_AUX_CONTROL_IRQ_EN                        8
+#define DPRX_AUX_CONTROL_TX_STROBE             7
+#define DPRX_AUX_CONTROL_LENGTH_SHIFT          0
+#define DPRX_AUX_CONTROL_LENGTH_MASK           0x1f
+
+#define DPRX_AUX_STATUS                                0x101
+#define DPRX_AUX_STATUS_MSG_READY              31
+#define DPRX_AUX_STATUS_READY_TO_TX            30
+
+#define DPRX_AUX_COMMAND                       0x102
+
+#define DPRX_AUX_HPD                           0x119
+#define DPRX_AUX_HPD_IRQ                       12
+#define DPRX_AUX_HPD_EN                                11
+
+/* DDC defines */
+
+#define DDC_EDID_ADDR          0x50
+#define DDC_SEGMENT_ADDR       0x30
+
+struct dprx_training_control {
+       u8 volt_swing;
+       u8 pre_emph;
+       bool max_swing;
+       bool max_pre_emph;
+};
+
+struct dprx_sink {
+       u8 edid[128 * DPRX_MAX_EDID_BLOCKS];
+       int blocks;
+       int offset;
+       int segment;
+};
+
+struct msg_transaction_rxbuf {
+       u8 buf[256];
+       int len;
+};
+
+struct msg_transaction_txbuf {
+       u8 buf[256];
+       int len;
+       int written;
+};
+
+struct msg_transaction_meta {
+       u8 lct;
+       u8 rad[8];
+       bool seqno;
+};
+
+struct dprx {
+       struct device *dev;
+       void __iomem *iobase;
+
+       struct v4l2_subdev subdev;
+       struct media_pad pads[4];
+
+       struct dprx_sink sinks[4];
+
+       int max_link_rate;
+       int max_lane_count;
+       bool multi_stream_support;
+       int max_stream_count;
+
+       u8 caps[16];
+       u8 guid[16];
+
+       struct dprx_training_control training_control[4];
+
+       u8 payload_allocate_set;
+       u8 payload_allocate_start_time_slot;
+       u8 payload_allocate_time_slot_count;
+       u8 payload_table[64];
+       u8 payload_table_updated;
+
+       u8  payload_id[4];
+       u32 payload_pbn[4];
+       u32 payload_pbn_total;
+
+       u8 irq_vector;
+
+       u8 down_req_buf[48];
+       u8 down_rep_buf[48];
+
+       struct msg_transaction_rxbuf mt_rxbuf[2];
+       struct msg_transaction_txbuf mt_txbuf[2];
+       struct msg_transaction_meta mt_meta[2];
+       bool mt_seqno;
+       bool mt_pending;
+       bool down_rep_pending;
+
+       spinlock_t lock;
+};
+
+struct aux_buf {
+       u8 data[20];
+       int len;
+};
+
+struct aux_msg {
+       u8 cmd;
+       u32 addr;
+       u8 len;
+       u8 data[16];
+};
+
+struct sideband_msg {
+       u8 lct;
+       u8 lcr;
+       u8 rad[8];
+       bool broadcast;
+       bool path_msg;
+       bool somt;
+       bool eomt;
+       bool seqno;
+
+       u8 body[48];
+       u8 body_len;
+};
+
+static void dprx_write(struct dprx *dprx, int addr, u32 val)
+{
+       writel(val, dprx->iobase + (addr * 4));
+}
+
+static u32 dprx_read(struct dprx *dprx, int addr)
+{
+       return readl(dprx->iobase + (addr * 4));
+}
+
+static void dprx_set_irq(struct dprx *dprx, int val)
+{
+       u32 reg;
+
+       reg = dprx_read(dprx, DPRX_AUX_CONTROL);
+       reg |= ~(1 << DPRX_AUX_CONTROL_IRQ_EN);
+       reg |= val << DPRX_AUX_CONTROL_IRQ_EN;
+       dprx_write(dprx, DPRX_AUX_CONTROL, reg);
+}
+
+static void dprx_set_hpd(struct dprx *dprx, int val)
+{
+       u32 reg;
+
+       reg = dprx_read(dprx, DPRX_AUX_HPD);
+       reg &= ~(1 << DPRX_AUX_HPD_EN);
+       reg |= val << DPRX_AUX_HPD_EN;
+       dprx_write(dprx, DPRX_AUX_HPD, reg);
+}
+
+static void dprx_pulse_hpd(struct dprx *dprx)
+{
+       u32 reg;
+
+       reg = dprx_read(dprx, DPRX_AUX_HPD);
+       reg |= 1 << DPRX_AUX_HPD_IRQ;
+       dprx_write(dprx, DPRX_AUX_HPD, reg);
+}
+
+static void dprx_clear_vc_payload_table(struct dprx *dprx)
+{
+       u32 reg;
+       int i;
+
+       memset(dprx->payload_table, 0, sizeof(dprx->payload_table));
+
+       for (i = 0; i < 8; i++)
+               dprx_write(dprx, DPRX_MST_VCPTAB(i), 0);
+
+       reg = dprx_read(dprx, DPRX_MST_CONTROL1);
+       reg &= ~(DPRX_MST_CONTROL1_VCP_IDS_MASK << 
DPRX_MST_CONTROL1_VCP_IDS_SHIFT);
+       reg |= 1 << DPRX_MST_CONTROL1_VCPTAB_UPD_FORCE;
+       dprx_write(dprx, DPRX_MST_CONTROL1, reg);
+}
+
+static void dprx_set_vc_payload_table(struct dprx *dprx)
+{
+       int i, j;
+       u32 reg;
+       u8 val;
+
+       /*
+        * The IP core only accepts VC payload IDs of 1-4. Thus, we need to
+        * remap the 1-63 range allowed by DisplayPort into 1-4. However, some
+        * hosts first set the VC payload table and then allocate the VC
+        * payload IDs, which means we can't remap the range immediately.
+        *
+        * It is probably possible to force a VC payload table update (without
+        * waiting for a ACT trigger) when the IDs change, but for now we just
+        * ignore IDs higher than 4.
+        */
+       for (i = 0; i < 8; i++) {
+               reg = 0;
+               for (j = 0; j < 8; j++) {
+                       val = dprx->payload_table[i*8+j];
+                       if (val <= 4)
+                               reg |= val << (j * 4);
+               }
+               dprx_write(dprx, DPRX_MST_VCPTAB(i), reg);
+       }
+
+       reg = dprx_read(dprx, DPRX_MST_CONTROL1);
+       reg |= 1 << DPRX_MST_CONTROL1_VCPTAB_UPD_REQ;
+       dprx_write(dprx, DPRX_MST_CONTROL1, reg);
+}
+
+static void dprx_set_vc_ids(struct dprx *dprx)
+{
+       u32 reg;
+       int i;
+
+       reg = dprx_read(dprx, DPRX_MST_CONTROL1);
+       reg &= ~(DPRX_MST_CONTROL1_VCP_IDS_MASK << 
DPRX_MST_CONTROL1_VCP_IDS_SHIFT);
+       for (i = 0; i < dprx->max_stream_count; i++) {
+               if (dprx->payload_id[i] <= 4)
+                       reg |= dprx->payload_id[i] << 
DPRX_MST_CONTROL1_VCP_ID_SHIFT(i);
+       }
+       dprx_write(dprx, DPRX_MST_CONTROL1, reg);
+}
+
+static void dprx_allocate_vc_payload(struct dprx *dprx, u8 start, u8 count, u8 
id)
+{
+       if (count > sizeof(dprx->payload_table) - start)
+               count = sizeof(dprx->payload_table) - start;
+       memset(dprx->payload_table + start, id, count);
+}
+
+static void dprx_deallocate_vc_payload(struct dprx *dprx, int start, u8 id)
+{
+       u8 to = start;
+       u8 i;
+
+       for (i = start; i < sizeof(dprx->payload_table); i++) {
+               if (dprx->payload_table[i] == id)
+                       dprx->payload_table[i] = 0;
+               else
+                       dprx->payload_table[to++] = dprx->payload_table[i];
+       }
+}
+
+static u32 dprx_full_pbn(struct dprx *dprx)
+{
+       u32 reg;
+       u32 lane_count;
+       u32 link_rate;
+
+       if ((dprx_read(dprx, DPRX_RX_STATUS) >> DPRX_RX_STATUS_INTERLANE_ALIGN) 
& 1) {
+               /* link training done - get current bandwidth */
+               reg = dprx_read(dprx, DPRX_RX_CONTROL);
+               lane_count = (reg >> DPRX_RX_CONTROL_LANE_COUNT_SHIFT) &
+                            DPRX_RX_CONTROL_LANE_COUNT_MASK;
+               link_rate  = (reg >> DPRX_RX_CONTROL_LINK_RATE_SHIFT) &
+                            DPRX_RX_CONTROL_LINK_RATE_MASK;
+       } else {
+               /* link training not done - get max bandwidth */
+               lane_count = dprx->max_lane_count;
+               link_rate  = dprx->max_link_rate;
+       }
+
+       return lane_count * link_rate * 32;
+}
+
+static int dprx_port_number_to_sink_idx(struct dprx *dprx, u8 port_number)
+{
+       /* check if port number is valid */
+       if (port_number < DP_MST_LOGICAL_PORT_0 ||
+           port_number >= DP_MST_LOGICAL_PORT_0 + dprx->max_stream_count)
+               return -1;
+
+       return port_number - DP_MST_LOGICAL_PORT_0;
+}
+
+static bool dprx_adjust_needed(struct dprx *dprx)
+{
+       u32 control;
+       u32 status;
+       u32 lane_count;
+       u32 lane_count_mask;
+       u32 pattern;
+
+       control = dprx_read(dprx, DPRX_RX_CONTROL);
+       status = dprx_read(dprx, DPRX_RX_STATUS);
+
+       pattern = (control >> DPRX_RX_CONTROL_TP_SHIFT) & 
DPRX_RX_CONTROL_TP_MASK;
+       lane_count = (control >> DPRX_RX_CONTROL_LANE_COUNT_SHIFT) &
+                    DPRX_RX_CONTROL_LANE_COUNT_MASK;
+       lane_count_mask = (1 << lane_count) - 1;
+
+       if (pattern == 0) {
+               /* link training not in progress */
+               return false;
+       } else if (pattern == 1) {
+               /* link training CR phase - check CR lock */
+               return (~status) & (lane_count_mask << 
DPRX_RX_STATUS_CR_LOCK_SHIFT);
+       }
+       /* link training EQ phase - check synbol lock and interlane align */
+       return (~status) & (lane_count_mask << DPRX_RX_STATUS_SYM_LOCK_SHIFT |
+                           1 << DPRX_RX_STATUS_INTERLANE_ALIGN);
+}
+
+/*
+ * Return next allowed voltage swing, and pre-emphasis pair.
+ * DisplayPort 1.2 spec, section 3.1.5.2
+ */
+static void dprx_training_control_next(struct dprx_training_control *ctl,
+                                      u8 *next_volt_swing, u8 *next_pre_emph)
+{
+       u8 volt_swing = ctl->volt_swing;
+       u8 pre_emph = ctl->pre_emph;
+
+       pre_emph++;
+       if (pre_emph > 2) {
+               volt_swing++;
+               pre_emph = 0;
+       }
+
+       if (volt_swing > 2 || (volt_swing == 2 && pre_emph == 2)) {
+               volt_swing = 0;
+               pre_emph = 0;
+       }
+
+       *next_volt_swing = volt_swing;
+       *next_pre_emph = pre_emph;
+}
+
+static int dprx_i2c_read(struct dprx_sink *sink, u8 addr, u8 *buf, int len)
+{
+       int offset;
+
+       if (len == 0)
+               return 0;
+
+       switch (addr) {
+       case DDC_EDID_ADDR:
+               offset = sink->offset + sink->segment * 256;
+               if (len + offset > sink->blocks * 128)
+                       return -1;
+               memcpy(buf, sink->edid + offset, len);
+               sink->offset += len;
+               break;
+       case DDC_SEGMENT_ADDR:
+               if (len > 1)
+                       return -1;
+               buf[0] = sink->segment;
+               break;
+       default:
+               return -1;
+       }
+
+       return 0;
+}
+
+static int dprx_i2c_write(struct dprx_sink *sink, u8 addr, u8 *buf, int len)
+{
+       if (len == 0)
+               return 0;
+       if (len > 1)
+               return -1;
+
+       switch (addr) {
+       case DDC_EDID_ADDR:
+               sink->offset = buf[0];
+               break;
+       case DDC_SEGMENT_ADDR:
+               sink->segment = buf[0];
+               break;
+       default:
+               return -1;
+       }
+
+       return 0;
+}
+
+static void dprx_i2c_stop(struct dprx_sink *sink)
+{
+       sink->segment = 0;
+}
+
+static void dprx_write_nak(struct dprx *dprx,
+                          struct drm_dp_sideband_msg_reply_body *rep,
+                          u8 req_type, u8 reason)
+{
+       rep->reply_type = DP_SIDEBAND_REPLY_NAK;
+       rep->req_type = req_type;
+
+       memcpy(rep->u.nak.guid, dprx->guid, sizeof(dprx->guid));
+       rep->u.nak.reason = reason;
+       rep->u.nak.nak_data = 0;
+}
+
+static void dprx_execute_link_address(struct dprx *dprx,
+                                     struct drm_dp_sideband_msg_req_body *req,
+                                     struct drm_dp_sideband_msg_reply_body 
*rep)
+{
+       struct drm_dp_link_address_ack_reply *link_address = &rep->u.link_addr;
+       struct drm_dp_link_addr_reply_port *port = link_address->ports;
+       int i;
+
+       rep->reply_type = DP_SIDEBAND_REPLY_ACK;
+       rep->req_type = DP_LINK_ADDRESS;
+
+       memcpy(link_address->guid, dprx->guid, sizeof(dprx->guid));
+       link_address->nports = dprx->max_stream_count + 1;
+
+       /* Port 0: input (physical) */
+       port->input_port = true;
+       port->peer_device_type = DP_PEER_DEVICE_SOURCE_OR_SST;
+       port->port_number = 0;
+       port->mcs = false;
+       port->ddps = true;
+       port++;
+
+       for (i = 0; i < dprx->max_stream_count; i++) {
+               /* Port 8 + n: internal sink number n (logical) */
+               port->input_port = false;
+               port->port_number = DP_MST_LOGICAL_PORT_0 + i;
+               port->mcs = false;
+               if (dprx->sinks[i].blocks > 0) {
+                       port->peer_device_type = DP_PEER_DEVICE_SST_SINK;
+                       port->ddps = true;
+               } else {
+                       port->peer_device_type = DP_PEER_DEVICE_NONE;
+                       port->ddps = false;
+               }
+               port->legacy_device_plug_status = false;
+               port->dpcd_revision = 0;
+               memset(port->peer_guid, 0, 16);
+               port->num_sdp_streams = 0;
+               port->num_sdp_stream_sinks = 0;
+               port++;
+       }
+}
+
+static void dprx_execute_connection_status_notify(struct dprx *dprx,
+                                                 struct 
drm_dp_sideband_msg_req_body *req,
+                                                 struct 
drm_dp_sideband_msg_reply_body *rep)
+{
+       rep->reply_type = DP_SIDEBAND_REPLY_ACK;
+       rep->req_type = DP_CONNECTION_STATUS_NOTIFY;
+}
+
+static void dprx_execute_enum_path_resources(struct dprx *dprx,
+                                            struct 
drm_dp_sideband_msg_req_body *req,
+                                            struct 
drm_dp_sideband_msg_reply_body *rep)
+{
+       u32 full_pbn = dprx_full_pbn(dprx);
+
+       rep->reply_type = DP_SIDEBAND_REPLY_ACK;
+       rep->req_type = DP_ENUM_PATH_RESOURCES;
+
+       rep->u.path_resources.port_number = req->u.port_num.port_number;
+       rep->u.path_resources.fec_capable = false;
+       rep->u.path_resources.full_payload_bw_number = full_pbn;
+       if (dprx->payload_pbn_total > full_pbn)
+               rep->u.path_resources.avail_payload_bw_number = 0;
+       else
+               rep->u.path_resources.avail_payload_bw_number = full_pbn - 
dprx->payload_pbn_total;
+}
+
+static void dprx_execute_allocate_payload(struct dprx *dprx,
+                                         struct drm_dp_sideband_msg_req_body 
*req,
+                                         struct drm_dp_sideband_msg_reply_body 
*rep)
+{
+       struct drm_dp_allocate_payload *a_req = &req->u.allocate_payload;
+       struct drm_dp_allocate_payload_ack_reply *a_rep = 
&rep->u.allocate_payload;
+       int sink_idx;
+
+       sink_idx = dprx_port_number_to_sink_idx(dprx, a_req->port_number);
+       if (sink_idx == -1) {
+               dprx_write_nak(dprx, rep, req->req_type, DP_NAK_BAD_PARAM);
+               return;
+       }
+
+       if (a_req->vcpi == 0) {
+               dprx_write_nak(dprx, rep, req->req_type, DP_NAK_BAD_PARAM);
+               return;
+       }
+
+       if (a_req->pbn > 0) {
+               if (dprx->payload_pbn[sink_idx] == 0) {
+                       /* New payload ID */
+                       dprx->payload_id[sink_idx] = a_req->vcpi;
+               } else if (dprx->payload_id[sink_idx] != a_req->vcpi) {
+                       /* At most one payload ID is allowed per sink */
+                       dprx_write_nak(dprx, rep, req->req_type, 
DP_NAK_ALLOCATE_FAIL);
+                       return;
+               }
+       }
+       WARN_ON_ONCE(dprx->payload_pbn_total < dprx->payload_pbn[sink_idx]);
+       dprx->payload_pbn_total -= dprx->payload_pbn[sink_idx];
+       dprx->payload_pbn_total += a_req->pbn;
+       dprx->payload_pbn[sink_idx] = a_req->pbn;
+
+       dprx_set_vc_ids(dprx);
+
+       rep->reply_type = DP_SIDEBAND_REPLY_ACK;
+       rep->req_type = DP_ALLOCATE_PAYLOAD;
+
+       a_rep->port_number = a_req->port_number;
+       a_rep->vcpi = a_req->vcpi;
+       a_rep->allocated_pbn = a_req->pbn;
+}
+
+static void dprx_execute_clear_payload_id_table(struct dprx *dprx,
+                                               struct 
drm_dp_sideband_msg_req_body *req,
+                                               struct 
drm_dp_sideband_msg_reply_body *rep)
+{
+       rep->reply_type = DP_SIDEBAND_REPLY_ACK;
+       rep->req_type = DP_CLEAR_PAYLOAD_ID_TABLE;
+
+       dprx_clear_vc_payload_table(dprx);
+}
+
+static void dprx_execute_remote_dpcd_read(struct dprx *dprx,
+                                         struct drm_dp_sideband_msg_req_body 
*req,
+                                         struct drm_dp_sideband_msg_reply_body 
*rep)
+{
+       struct drm_dp_remote_dpcd_read *read_req = &req->u.dpcd_read;
+       struct drm_dp_remote_dpcd_read_ack_reply *read_rep = 
&rep->u.remote_dpcd_read_ack;
+
+       rep->reply_type = DP_SIDEBAND_REPLY_ACK;
+       rep->req_type = DP_REMOTE_DPCD_READ;
+
+       read_rep->port_number = read_req->port_number;
+       read_rep->num_bytes = read_req->num_bytes;
+       memset(read_rep->bytes, 0, read_req->num_bytes);
+}
+
+static void dprx_execute_remote_i2c_read(struct dprx *dprx,
+                                        struct drm_dp_sideband_msg_req_body 
*req,
+                                        struct drm_dp_sideband_msg_reply_body 
*rep)
+{
+       struct drm_dp_remote_i2c_read *read_req = &req->u.i2c_read;
+       struct drm_dp_remote_i2c_read_ack_reply *read_rep = 
&rep->u.remote_i2c_read_ack;
+       struct drm_dp_remote_i2c_read_tx *tx;
+       struct dprx_sink *sink;
+       int sink_idx;
+       int res;
+       int i;
+
+       sink_idx = dprx_port_number_to_sink_idx(dprx, read_req->port_number);
+       if (sink_idx == -1) {
+               dprx_write_nak(dprx, rep, req->req_type, DP_NAK_BAD_PARAM);
+               return;
+       }
+       sink = &dprx->sinks[sink_idx];
+
+       for (i = 0; i < read_req->num_transactions; i++) {
+               tx = &read_req->transactions[i];
+               res = dprx_i2c_write(sink, tx->i2c_dev_id, tx->bytes, 
tx->num_bytes);
+               if (res)
+                       goto i2c_err;
+               if (!tx->no_stop_bit)
+                       dprx_i2c_stop(sink);
+       }
+
+       res = dprx_i2c_read(sink, read_req->read_i2c_device_id,
+                                 read_rep->bytes, read_req->num_bytes_read);
+       if (res)
+               goto i2c_err;
+       dprx_i2c_stop(sink);
+
+       rep->reply_type = DP_SIDEBAND_REPLY_ACK;
+       rep->req_type = DP_REMOTE_I2C_READ;
+
+       read_rep->port_number = read_req->port_number;
+       read_rep->num_bytes = read_req->num_bytes_read;
+       return;
+
+i2c_err:
+       dprx_i2c_stop(sink);
+       dprx_write_nak(dprx, rep, req->req_type, DP_NAK_I2C_NAK);
+}
+
+static void dprx_execute_remote_i2c_write(struct dprx *dprx,
+                                         struct drm_dp_sideband_msg_req_body 
*req,
+                                         struct drm_dp_sideband_msg_reply_body 
*rep)
+{
+       struct drm_dp_remote_i2c_write *write_req = &req->u.i2c_write;
+       struct drm_dp_remote_i2c_write_ack_reply *write_rep = 
&rep->u.remote_i2c_write_ack;
+       struct dprx_sink *sink;
+       int sink_idx;
+       int res;
+
+       sink_idx = dprx_port_number_to_sink_idx(dprx, write_req->port_number);
+       if (sink_idx == -1) {
+               dprx_write_nak(dprx, rep, req->req_type, DP_NAK_BAD_PARAM);
+               return;
+       }
+       sink = &dprx->sinks[sink_idx];
+
+       res = dprx_i2c_write(sink, write_req->write_i2c_device_id,
+                                  write_req->bytes, write_req->num_bytes);
+       dprx_i2c_stop(sink);
+       if (res) {
+               dprx_write_nak(dprx, rep, req->req_type, DP_NAK_I2C_NAK);
+               return;
+       }
+
+       rep->reply_type = DP_SIDEBAND_REPLY_ACK;
+       rep->req_type = DP_REMOTE_I2C_WRITE;
+       write_rep->port_number = write_req->port_number;
+}
+
+static void dprx_execute_power_up_phy(struct dprx *dprx,
+                                     struct drm_dp_sideband_msg_req_body *req,
+                                     struct drm_dp_sideband_msg_reply_body 
*rep)
+{
+       rep->reply_type = DP_SIDEBAND_REPLY_ACK;
+       rep->req_type = DP_POWER_UP_PHY;
+       rep->u.port_number.port_number = req->u.port_num.port_number;
+}
+
+static void dprx_execute_power_down_phy(struct dprx *dprx,
+                                       struct drm_dp_sideband_msg_req_body 
*req,
+                                       struct drm_dp_sideband_msg_reply_body 
*rep)
+{
+       rep->reply_type = DP_SIDEBAND_REPLY_ACK;
+       rep->req_type = DP_POWER_DOWN_PHY;
+       rep->u.port_number.port_number = req->u.port_num.port_number;
+}
+
+static void dprx_encode_sideband_msg(struct sideband_msg *msg, u8 *buf)
+{
+       int idx = 0;
+       int i;
+       u8 crc4;
+
+       buf[idx++] = ((msg->lct & 0xf) << 4) | (msg->lcr & 0xf);
+       for (i = 0; i < (msg->lct / 2); i++)
+               buf[idx++] = msg->rad[i];
+       buf[idx++] = (msg->broadcast << 7) | (msg->path_msg << 6) |
+               ((msg->body_len + 1) & 0x3f);
+       buf[idx++] = (msg->somt << 7) | (msg->eomt << 6) | (msg->seqno << 4);
+
+       crc4 = crc_dp_msg_header(buf, (idx * 2) - 1);
+       buf[idx - 1] |= (crc4 & 0xf);
+
+       memcpy(&buf[idx], msg->body, msg->body_len);
+       idx += msg->body_len;
+       buf[idx] = crc_dp_msg_data(msg->body, msg->body_len);
+}
+
+static bool dprx_decode_sideband_msg(struct sideband_msg *msg, u8 *buf, int 
buflen)
+{
+       u8 hdr_crc;
+       u8 hdr_len;
+       u8 body_crc;
+       int i;
+       u8 idx;
+
+       if (buf[0] == 0)
+               return false;
+       hdr_len = 3;
+       hdr_len += ((buf[0] & 0xf0) >> 4) / 2;
+       if (hdr_len > buflen)
+               return false;
+       hdr_crc = crc_dp_msg_header(buf, (hdr_len * 2) - 1);
+       if ((hdr_crc & 0xf) != (buf[hdr_len - 1] & 0xf))
+               return false;
+
+       msg->lct = (buf[0] & 0xf0) >> 4;
+       msg->lcr = (buf[0] & 0xf);
+       idx = 1;
+       for (i = 0; i < (msg->lct / 2); i++)
+               msg->rad[i] = buf[idx++];
+       msg->broadcast = (buf[idx] >> 7) & 0x1;
+       msg->path_msg = (buf[idx] >> 6) & 0x1;
+       msg->body_len = (buf[idx] & 0x3f) - 1;
+       idx++;
+       msg->somt = (buf[idx] >> 7) & 0x1;
+       msg->eomt = (buf[idx] >> 6) & 0x1;
+       msg->seqno = (buf[idx] >> 4) & 0x1;
+       idx++;
+
+       if (hdr_len + msg->body_len + 1 != buflen)
+               return false;
+
+       body_crc = crc_dp_msg_data(&buf[idx], msg->body_len);
+       if (body_crc != buf[idx + msg->body_len])
+               return false;
+
+       memcpy(msg->body, &buf[idx], msg->body_len);
+       idx += msg->body_len;
+
+       return true;
+}
+
+static bool dprx_decode_port_number_req(struct drm_dp_port_number_req 
*port_num, u8 *buf, int len)
+{
+       if (len != 1)
+               return false;
+
+       port_num->port_number = buf[0] >> 4;
+
+       return true;
+}
+
+static bool
+dprx_decode_connection_status_notify_req(struct 
drm_dp_connection_status_notify *conn_stat,
+                                        u8 *buf, int len)
+{
+       int idx = 0;
+
+       if (len != 18)
+               return false;
+
+       conn_stat->port_number = buf[idx++];
+       memcpy(conn_stat->guid, &buf[idx], 16);
+       idx += 16;
+       conn_stat->legacy_device_plug_status = (buf[idx] >> 6) & 1;
+       conn_stat->displayport_device_plug_status = (buf[idx] >> 5) & 1;
+       conn_stat->message_capability_status = (buf[idx] >> 4) & 1;
+       conn_stat->input_port = (buf[idx] >> 3) & 1;
+       conn_stat->peer_device_type = buf[idx] & 0x7;
+
+       return true;
+}
+
+static bool dprx_decode_allocate_payload_req(struct drm_dp_allocate_payload 
*alloc_payload,
+                                            u8 *buf, int len)
+{
+       int idx = 0;
+       int i;
+
+       if (len < 4)
+               return false;
+
+       alloc_payload->port_number = buf[idx] >> 4;
+       alloc_payload->number_sdp_streams = buf[idx++] & 0xf;
+       alloc_payload->vcpi = buf[idx++] & 0x7f;
+       alloc_payload->pbn = buf[idx] << 8 | buf[idx + 1];
+       idx += 2;
+
+       if (len != idx + (alloc_payload->number_sdp_streams + 1) / 2)
+               return false;
+
+       for (i = 0; i < alloc_payload->number_sdp_streams; i++) {
+               if ((i & 1) == 0) {
+                       alloc_payload->sdp_stream_sink[i] = buf[idx] >> 4;
+               } else {
+                       alloc_payload->sdp_stream_sink[i] = buf[idx] & 0xf;
+                       idx++;
+               }
+       }
+
+       return true;
+}
+
+static bool dprx_decode_remote_dpcd_read_req(struct drm_dp_remote_dpcd_read 
*dpcd_read,
+                                            u8 *buf, int len)
+{
+       if (len != 4)
+               return false;
+
+       dpcd_read->port_number = buf[0] >> 4;
+       dpcd_read->dpcd_address = (buf[0] & 0xf) << 16 | buf[1] << 8 | buf[2];
+       dpcd_read->num_bytes = buf[3];
+
+       return true;
+}
+
+static bool dprx_decode_remote_i2c_read_req(struct drm_dp_remote_i2c_read 
*i2c_read,
+                                           u8 *buf, int len)
+{
+       struct drm_dp_remote_i2c_read_tx *tx;
+       int idx = 0;
+       int i;
+
+       if (len < 1)
+               return false;
+
+       i2c_read->port_number = buf[idx] >> 4;
+       i2c_read->num_transactions = buf[idx] & 0x3;
+       idx++;
+
+       for (i = 0; i < i2c_read->num_transactions; i++) {
+               tx = &i2c_read->transactions[i];
+               if (len < idx + 2)
+                       return false;
+               tx->i2c_dev_id = buf[idx++] & 0x7f;
+               tx->num_bytes = buf[idx++];
+               if (len < idx + tx->num_bytes + 1)
+                       return -1;
+               tx->bytes = &buf[idx];
+               idx += tx->num_bytes;
+               tx->no_stop_bit = (buf[idx] >> 4) & 1;
+               tx->i2c_transaction_delay = buf[idx] & 0xf;
+               idx++;
+       }
+
+       if (len != idx + 2)
+               return false;
+
+       i2c_read->read_i2c_device_id = buf[idx++] & 0x7f;
+       i2c_read->num_bytes_read = buf[idx++];
+
+       return true;
+}
+
+static bool dprx_decode_remote_i2c_write_req(struct drm_dp_remote_i2c_write 
*i2c_write,
+                                            u8 *buf, int len)
+{
+       int idx = 0;
+
+       if (len < 3)
+               return false;
+
+       i2c_write->port_number = buf[idx++] >> 4;
+       i2c_write->write_i2c_device_id = buf[idx++] & 0x7f;
+       i2c_write->num_bytes = buf[idx++];
+
+       if (len != idx + i2c_write->num_bytes)
+               return false;
+
+       i2c_write->bytes = &buf[idx];
+
+       return true;
+}
+
+static bool dprx_decode_sideband_req(struct drm_dp_sideband_msg_req_body *req, 
u8 *buf, int len)
+{
+       if (len == 0)
+               return false;
+
+       req->req_type = buf[0] & 0x7f;
+       buf++;
+       len--;
+
+       switch (req->req_type) {
+       case DP_LINK_ADDRESS:
+       case DP_CLEAR_PAYLOAD_ID_TABLE:
+               return len == 0; /* no request data */
+       case DP_ENUM_PATH_RESOURCES:
+       case DP_POWER_UP_PHY:
+       case DP_POWER_DOWN_PHY:
+               return dprx_decode_port_number_req(&req->u.port_num, buf, len);
+       case DP_CONNECTION_STATUS_NOTIFY:
+               return 
dprx_decode_connection_status_notify_req(&req->u.conn_stat, buf, len);
+       case DP_ALLOCATE_PAYLOAD:
+               return 
dprx_decode_allocate_payload_req(&req->u.allocate_payload, buf, len);
+       case DP_REMOTE_DPCD_READ:
+               return dprx_decode_remote_dpcd_read_req(&req->u.dpcd_read, buf, 
len);
+       case DP_REMOTE_I2C_READ:
+               return dprx_decode_remote_i2c_read_req(&req->u.i2c_read, buf, 
len);
+       case DP_REMOTE_I2C_WRITE:
+               return dprx_decode_remote_i2c_write_req(&req->u.i2c_write, buf, 
len);
+       default:
+               return false;
+       }
+}
+
+static void dprx_encode_sideband_rep(struct drm_dp_sideband_msg_reply_body 
*rep, u8 *buf, int *len)
+{
+       int idx = 0;
+       int i;
+
+       buf[idx++] = (rep->reply_type & 0x1) << 7 | (rep->req_type & 0x7f);
+
+       if (rep->reply_type) {
+               memcpy(&buf[idx], rep->u.nak.guid, 16);
+               idx += 16;
+               buf[idx++] = rep->u.nak.reason;
+               buf[idx++] = rep->u.nak.nak_data;
+               *len = idx;
+               return;
+       }
+
+       switch (rep->req_type) {
+       case DP_LINK_ADDRESS: {
+               struct drm_dp_link_address_ack_reply *link_addr = 
&rep->u.link_addr;
+               struct drm_dp_link_addr_reply_port *port;
+
+               memcpy(&buf[idx], link_addr->guid, 16);
+               idx += 16;
+               buf[idx++] = link_addr->nports;
+               for (i = 0; i < link_addr->nports; i++) {
+                       port = &link_addr->ports[i];
+                       buf[idx++] = port->input_port << 7 | 
port->peer_device_type << 4 |
+                                    port->port_number;
+                       if (port->input_port == 0) {
+                               buf[idx++] = port->mcs << 7 | port->ddps << 6 |
+                                            port->legacy_device_plug_status << 
5;
+                               buf[idx++] = port->dpcd_revision;
+                               memcpy(&buf[idx], port->peer_guid, 16);
+                               idx += 16;
+                               buf[idx++] = port->num_sdp_streams << 4 |
+                                            port->num_sdp_stream_sinks;
+                       } else {
+                               buf[idx++] = port->mcs << 7 | port->ddps << 6;
+                       }
+               }
+               break;
+       }
+       case DP_ENUM_PATH_RESOURCES: {
+               struct drm_dp_enum_path_resources_ack_reply *path_res = 
&rep->u.path_resources;
+
+               buf[idx++] = path_res->port_number << 4 | path_res->fec_capable;
+               buf[idx++] = path_res->full_payload_bw_number >> 8;
+               buf[idx++] = path_res->full_payload_bw_number & 0xff;
+               buf[idx++] = path_res->avail_payload_bw_number >> 8;
+               buf[idx++] = path_res->avail_payload_bw_number & 0xff;
+               break;
+       }
+       case DP_ALLOCATE_PAYLOAD: {
+               struct drm_dp_allocate_payload_ack_reply *alloc_payload = 
&rep->u.allocate_payload;
+
+               buf[idx++] = alloc_payload->port_number << 4;
+               buf[idx++] = alloc_payload->vcpi & 0x3f;
+               buf[idx++] = alloc_payload->allocated_pbn >> 8;
+               buf[idx++] = alloc_payload->allocated_pbn & 0xff;
+               break;
+       }
+       case DP_REMOTE_DPCD_READ: {
+               struct drm_dp_remote_dpcd_read_ack_reply *dpcd_read = 
&rep->u.remote_dpcd_read_ack;
+
+               buf[idx++] = dpcd_read->port_number & 0xf;
+               buf[idx++] = dpcd_read->num_bytes;
+               memcpy(&buf[idx], dpcd_read->bytes, dpcd_read->num_bytes);
+               idx += dpcd_read->num_bytes;
+               break;
+       }
+       case DP_REMOTE_I2C_READ: {
+               struct drm_dp_remote_i2c_read_ack_reply *i2c_read = 
&rep->u.remote_i2c_read_ack;
+
+               buf[idx++] = i2c_read->port_number & 0xf;
+               buf[idx++] = i2c_read->num_bytes;
+               memcpy(&buf[idx], i2c_read->bytes, i2c_read->num_bytes);
+               idx += i2c_read->num_bytes;
+               break;
+       }
+       case DP_REMOTE_I2C_WRITE:
+               buf[idx++] = rep->u.remote_i2c_write_ack.port_number & 0xf;
+               break;
+       case DP_POWER_UP_PHY:
+       case DP_POWER_DOWN_PHY:
+               buf[idx++] = rep->u.port_number.port_number << 4;
+               break;
+       }
+       *len = idx;
+}
+
+static void dprx_execute_msg_transaction(struct dprx *dprx,
+                                        struct drm_dp_sideband_msg_req_body 
*req,
+                                        struct drm_dp_sideband_msg_reply_body 
*rep)
+{
+       switch (req->req_type) {
+       case DP_LINK_ADDRESS:
+               dprx_execute_link_address(dprx, req, rep);
+               break;
+       case DP_CONNECTION_STATUS_NOTIFY:
+               dprx_execute_connection_status_notify(dprx, req, rep);
+               break;
+       case DP_ENUM_PATH_RESOURCES:
+               dprx_execute_enum_path_resources(dprx, req, rep);
+               break;
+       case DP_ALLOCATE_PAYLOAD:
+               dprx_execute_allocate_payload(dprx, req, rep);
+               break;
+       case DP_CLEAR_PAYLOAD_ID_TABLE:
+               dprx_execute_clear_payload_id_table(dprx, req, rep);
+               break;
+       case DP_REMOTE_DPCD_READ:
+               dprx_execute_remote_dpcd_read(dprx, req, rep);
+               break;
+       case DP_REMOTE_I2C_READ:
+               dprx_execute_remote_i2c_read(dprx, req, rep);
+               break;
+       case DP_REMOTE_I2C_WRITE:
+               dprx_execute_remote_i2c_write(dprx, req, rep);
+               break;
+       case DP_POWER_UP_PHY:
+               dprx_execute_power_up_phy(dprx, req, rep);
+               break;
+       case DP_POWER_DOWN_PHY:
+               dprx_execute_power_down_phy(dprx, req, rep);
+               break;
+       default:
+               dprx_write_nak(dprx, rep, req->req_type, DP_NAK_BAD_PARAM);
+               break;
+       }
+}
+
+static void dprx_handle_msg_transaction(struct dprx *dprx,
+                                       struct msg_transaction_rxbuf *rxbuf,
+                                       struct msg_transaction_txbuf *txbuf)
+{
+       bool decoded;
+       struct drm_dp_sideband_msg_req_body req;
+       struct drm_dp_sideband_msg_reply_body rep;
+
+       decoded = dprx_decode_sideband_req(&req, rxbuf->buf, rxbuf->len);
+       if (decoded)
+               dprx_execute_msg_transaction(dprx, &req, &rep);
+       else
+               dprx_write_nak(dprx, &rep, req.req_type, DP_NAK_BAD_PARAM);
+       dprx_encode_sideband_rep(&rep, txbuf->buf, &txbuf->len);
+       txbuf->written = 0;
+}
+
+static void dprx_msg_transaction_append(struct msg_transaction_rxbuf *rxbuf,
+                                       struct msg_transaction_meta *meta,
+                                       struct sideband_msg *msg)
+{
+       int append_len;
+
+       append_len = min(msg->body_len, sizeof(rxbuf->buf) - rxbuf->len);
+       memcpy(rxbuf->buf + rxbuf->len, msg->body, append_len);
+       rxbuf->len += append_len;
+
+       if (msg->somt) {
+               meta->lct = msg->lct;
+               memcpy(meta->rad, msg->rad, msg->lct / 2);
+               meta->seqno = msg->seqno;
+       }
+}
+
+static void dprx_msg_transaction_extract(struct msg_transaction_txbuf *txbuf,
+                                        struct msg_transaction_meta *meta,
+                                        struct sideband_msg *msg)
+{
+       int hdr_len = 3 + meta->lct / 2;
+       int body_len;
+       bool somt;
+       bool eomt;
+
+       body_len = txbuf->len - txbuf->written;
+       /* trim body_len so that the sideband msg fits into 48 bytes */
+       body_len = min(body_len, 48 - 1 - hdr_len);
+
+       somt = (txbuf->written == 0);
+       eomt = (txbuf->written + body_len == txbuf->len);
+
+       msg->lct = meta->lct;
+       msg->lcr = meta->lct - 1;
+       memcpy(msg->rad, meta->rad, meta->lct / 2);
+       msg->broadcast = false;
+       msg->path_msg = false;
+       msg->somt = somt;
+       msg->eomt = eomt;
+       msg->seqno = meta->seqno;
+
+       memcpy(msg->body, txbuf->buf + txbuf->written, body_len);
+       msg->body_len = body_len;
+
+       txbuf->written += body_len;
+}
+
+static void dprx_msg_transaction_clear_rxbuf(struct msg_transaction_rxbuf 
*rxbuf)
+{
+       rxbuf->len = 0;
+}
+
+static void dprx_msg_transaction_clear_txbuf(struct msg_transaction_txbuf 
*txbuf)
+{
+       txbuf->len = 0;
+       txbuf->written = 0;
+}
+
+static bool dprx_msg_transaction_txbuf_empty(struct msg_transaction_txbuf 
*txbuf)
+{
+       return txbuf->written == txbuf->len;
+}
+
+static void dprx_write_pending_sideband_msg(struct dprx *dprx)
+{
+       struct msg_transaction_txbuf *txbuf;
+       struct msg_transaction_meta *meta;
+       struct sideband_msg msg;
+
+       if (WARN_ON_ONCE(!dprx->mt_pending))
+               return;
+
+       txbuf = &dprx->mt_txbuf[dprx->mt_seqno];
+       meta = &dprx->mt_meta[dprx->mt_seqno];
+
+       dprx_msg_transaction_extract(txbuf, meta, &msg);
+       if (dprx_msg_transaction_txbuf_empty(txbuf)) {
+               dprx->mt_seqno = !dprx->mt_seqno;
+               txbuf = &dprx->mt_txbuf[dprx->mt_seqno];
+               if (dprx_msg_transaction_txbuf_empty(txbuf))
+                       dprx->mt_pending = false;
+       }
+
+       dprx_encode_sideband_msg(&msg, dprx->down_rep_buf);
+}
+
+static void dprx_signal_irq(struct dprx *dprx, int irq)
+{
+       dprx->irq_vector |= irq;
+       dprx_pulse_hpd(dprx);
+}
+
+static void dprx_handle_sideband_msg(struct dprx *dprx, struct sideband_msg 
*msg)
+{
+       struct msg_transaction_rxbuf *rxbuf = &dprx->mt_rxbuf[msg->seqno];
+       struct msg_transaction_txbuf *txbuf = &dprx->mt_txbuf[msg->seqno];
+       struct msg_transaction_meta *meta = &dprx->mt_meta[msg->seqno];
+
+       if (msg->somt)
+               dprx_msg_transaction_clear_rxbuf(rxbuf);
+       dprx_msg_transaction_append(rxbuf, meta, msg);
+
+       if (msg->eomt) {
+               /* drop the message if txbuf isn't empty */
+               if (!dprx_msg_transaction_txbuf_empty(txbuf))
+                       return;
+               dprx_handle_msg_transaction(dprx, rxbuf, txbuf);
+
+               if (!dprx->mt_pending) {
+                       dprx->mt_pending = true;
+                       dprx->mt_seqno = msg->seqno;
+                       if (!dprx->down_rep_pending) {
+                               dprx_write_pending_sideband_msg(dprx);
+                               dprx_signal_irq(dprx, DP_DOWN_REP_MSG_RDY);
+                               dprx->down_rep_pending = true;
+                       }
+               }
+       }
+}
+
+static void dprx_init_caps(struct dprx *dprx)
+{
+       memset(dprx->caps, 0, sizeof(dprx->caps));
+       dprx->caps[DP_DPCD_REV]                 = DP_DPCD_REV_14;
+       dprx->caps[DP_MAX_LINK_RATE]            = dprx->max_link_rate;
+       dprx->caps[DP_MAX_LANE_COUNT]           = DP_ENHANCED_FRAME_CAP | 
DP_TPS3_SUPPORTED |
+                                                 dprx->max_lane_count;
+       dprx->caps[DP_MAX_DOWNSPREAD]           = DP_TPS4_SUPPORTED | 
DP_MAX_DOWNSPREAD_0_5;
+       dprx->caps[DP_MAIN_LINK_CHANNEL_CODING] = DP_CAP_ANSI_8B10B;
+       dprx->caps[DP_RECEIVE_PORT_0_CAP_0]     = DP_LOCAL_EDID_PRESENT;
+}
+
+static u8 dprx_read_caps(struct dprx *dprx, u32 offset)
+{
+       return dprx->caps[offset];
+}
+
+static u8 dprx_read_mstm_cap(struct dprx *dprx)
+{
+       return dprx->multi_stream_support;
+}
+
+static u8 dprx_read_guid(struct dprx *dprx, u32 offset)
+{
+       return dprx->guid[offset];
+}
+
+static void dprx_write_guid(struct dprx *dprx, u32 offset, u8 val)
+{
+       dprx->guid[offset] = val;
+}
+
+static u8 dprx_read_link_bw(struct dprx *dprx)
+{
+       u32 reg = dprx_read(dprx, DPRX_RX_CONTROL);
+
+       return (reg >> DPRX_RX_CONTROL_LINK_RATE_SHIFT) & 
DPRX_RX_CONTROL_LINK_RATE_MASK;
+}
+
+static void dprx_write_link_bw(struct dprx *dprx, u8 val)
+{
+       u32 reg;
+
+       if (val != DP_LINK_BW_1_62 && val != DP_LINK_BW_2_7 &&
+           val != DP_LINK_BW_5_4  && val != DP_LINK_BW_8_1)
+               return;
+
+       if (val > dprx->max_link_rate)
+               return;
+
+       reg = dprx_read(dprx, DPRX_RX_CONTROL);
+       reg &= ~(DPRX_RX_CONTROL_LINK_RATE_MASK << 
DPRX_RX_CONTROL_LINK_RATE_SHIFT);
+       reg |= val << DPRX_RX_CONTROL_LINK_RATE_SHIFT;
+       reg |= 1 << DPRX_RX_CONTROL_RECONFIG_LINKRATE;
+       dprx_write(dprx, DPRX_RX_CONTROL, reg);
+}
+
+static u8 dprx_read_lane_count(struct dprx *dprx)
+{
+       u32 reg = dprx_read(dprx, DPRX_RX_CONTROL);
+
+       return (reg >> DPRX_RX_CONTROL_LANE_COUNT_SHIFT) & 
DPRX_RX_CONTROL_LANE_COUNT_MASK;
+}
+
+static void dprx_write_lane_count(struct dprx *dprx, u8 val)
+{
+       u32 reg;
+       u8 lane_count;
+
+       lane_count = val & DP_LANE_COUNT_MASK;
+
+       if (lane_count != 1 && lane_count != 2 && lane_count != 4)
+               return;
+
+       if (lane_count > dprx->max_lane_count)
+               return;
+
+       reg = dprx_read(dprx, DPRX_RX_CONTROL);
+       reg &= ~(DPRX_RX_CONTROL_LANE_COUNT_MASK << 
DPRX_RX_CONTROL_LANE_COUNT_SHIFT);
+       reg |= lane_count << DPRX_RX_CONTROL_LANE_COUNT_SHIFT;
+       dprx_write(dprx, DPRX_RX_CONTROL, reg);
+}
+
+static u8 dprx_read_training_pattern(struct dprx *dprx)
+{
+       u32 reg;
+       u32 pattern;
+       u32 scrambler_disable;
+       u8 result = 0;
+
+       reg = dprx_read(dprx, DPRX_RX_CONTROL);
+       pattern = (reg >> DPRX_RX_CONTROL_TP_SHIFT) & DPRX_RX_CONTROL_TP_MASK;
+       scrambler_disable = (reg >> DPRX_RX_CONTROL_SCRAMBLER_DISABLE) & 1;
+
+       if (scrambler_disable)
+               result |= DP_LINK_SCRAMBLING_DISABLE;
+       result |= pattern;
+
+       return result;
+}
+
+static void dprx_write_training_pattern(struct dprx *dprx, u8 val)
+{
+       u8 pattern;
+       u8 scrambler_disable;
+       u32 reg;
+
+       pattern = val & DP_TRAINING_PATTERN_MASK_1_4;
+       scrambler_disable = !!(val & DP_LINK_SCRAMBLING_DISABLE);
+
+       reg = dprx_read(dprx, DPRX_RX_CONTROL);
+       reg &= ~(DPRX_RX_CONTROL_TP_MASK << DPRX_RX_CONTROL_TP_SHIFT);
+       reg |= pattern << DPRX_RX_CONTROL_TP_SHIFT;
+       reg &= ~(1 << DPRX_RX_CONTROL_SCRAMBLER_DISABLE);
+       reg |= scrambler_disable << DPRX_RX_CONTROL_SCRAMBLER_DISABLE;
+       dprx_write(dprx, DPRX_RX_CONTROL, reg);
+}
+
+static u8 dprx_read_training_lane(struct dprx *dprx, u32 offset)
+{
+       struct dprx_training_control *ctl = &dprx->training_control[offset];
+       u8 result = 0;
+
+       result |= ctl->volt_swing << DP_TRAIN_VOLTAGE_SWING_SHIFT;
+       if (ctl->max_swing)
+               result |= DP_TRAIN_MAX_SWING_REACHED;
+       result |= ctl->pre_emph << DP_TRAIN_PRE_EMPHASIS_SHIFT;
+       if (ctl->max_pre_emph)
+               result |= DP_TRAIN_MAX_PRE_EMPHASIS_REACHED;
+
+       return result;
+}
+
+static void dprx_write_training_lane(struct dprx *dprx, u32 offset, u8 val)
+{
+       struct dprx_training_control *ctl = &dprx->training_control[offset];
+
+       ctl->volt_swing   = (val & DP_TRAIN_VOLTAGE_SWING_MASK) >> 
DP_TRAIN_VOLTAGE_SWING_SHIFT;
+       ctl->max_swing    = (val & DP_TRAIN_MAX_SWING_REACHED);
+       ctl->pre_emph     = (val & DP_TRAIN_PRE_EMPHASIS_MASK) >> 
DP_TRAIN_PRE_EMPHASIS_SHIFT;
+       ctl->max_pre_emph = (val & DP_TRAIN_MAX_PRE_EMPHASIS_REACHED);
+}
+
+static u8 dprx_read_mstm_ctrl(struct dprx *dprx)
+{
+       return (dprx_read(dprx, DPRX_MST_CONTROL1) >> DPRX_MST_CONTROL1_MST_EN) 
& 1;
+}
+
+static void dprx_write_mstm_ctrl(struct dprx *dprx, u8 val)
+{
+       u8 mst_en = !!(val & DP_MST_EN);
+       u32 reg;
+
+       reg = dprx_read(dprx, DPRX_MST_CONTROL1);
+       reg &= ~(1 << DPRX_MST_CONTROL1_MST_EN);
+       reg |= mst_en << DPRX_MST_CONTROL1_MST_EN;
+       dprx_write(dprx, DPRX_MST_CONTROL1, reg);
+}
+
+static void dprx_handle_payload_allocate(struct dprx *dprx)
+{
+       u8 id = dprx->payload_allocate_set;
+       u8 start = dprx->payload_allocate_start_time_slot;
+       u8 count = dprx->payload_allocate_time_slot_count;
+
+       if (id == 0 && start == 0 && count == 0x3f) {
+               dprx_clear_vc_payload_table(dprx);
+       } else {
+               if (count == 0)
+                       dprx_deallocate_vc_payload(dprx, start, id);
+               else
+                       dprx_allocate_vc_payload(dprx, start, count, id);
+               dprx_set_vc_payload_table(dprx);
+       }
+       dprx->payload_table_updated = 1;
+}
+
+static u8 dprx_read_payload_allocate_set(struct dprx *dprx)
+{
+       return dprx->payload_allocate_set;
+}
+
+static void dprx_write_payload_allocate_set(struct dprx *dprx, u8 val)
+{
+       dprx->payload_allocate_set = val & DP_PAYLOAD_ALLOCATE_SET_MASK;
+}
+
+static u8 dprx_read_payload_allocate_start_time_slot(struct dprx *dprx)
+{
+       return dprx->payload_allocate_start_time_slot;
+}
+
+static void dprx_write_payload_allocate_start_time_slot(struct dprx *dprx, u8 
val)
+{
+       dprx->payload_allocate_start_time_slot = val & 
DP_PAYLOAD_ALLOCATE_START_TIME_SLOT_MASK;
+}
+
+static u8 dprx_read_payload_allocate_time_slot_count(struct dprx *dprx)
+{
+       return dprx->payload_allocate_time_slot_count;
+}
+
+static void dprx_write_payload_allocate_time_slot_count(struct dprx *dprx, u8 
val)
+{
+       dprx->payload_allocate_time_slot_count = val & 
DP_PAYLOAD_ALLOCATE_TIME_SLOT_COUNT_MASK;
+       dprx_handle_payload_allocate(dprx);
+}
+
+static u8 dprx_read_sink_count(struct dprx *dprx)
+{
+       return dprx->max_stream_count;
+}
+
+static u8 dprx_read_device_service_irq_vector(struct dprx *dprx)
+{
+       return dprx->irq_vector;
+}
+
+static void dprx_write_device_service_irq_vector(struct dprx *dprx, u8 val)
+{
+       dprx->irq_vector &= ~val;
+
+       if (val & DP_DOWN_REP_MSG_RDY) {
+               if (dprx->mt_pending) {
+                       dprx_write_pending_sideband_msg(dprx);
+                       dprx_signal_irq(dprx, DP_DOWN_REP_MSG_RDY);
+               } else {
+                       dprx->down_rep_pending = false;
+               }
+       }
+}
+
+static u8 dprx_read_lane0_1_status(struct dprx *dprx)
+{
+       u32 reg;
+       u8 res = 0;
+
+       reg = dprx_read(dprx, DPRX_RX_STATUS);
+       if ((reg >> DPRX_RX_STATUS_CR_LOCK(0)) & 1)
+               res |= DP_LANE_CR_DONE;
+       if ((reg >> DPRX_RX_STATUS_CR_LOCK(1)) & 1)
+               res |= DP_LANE_CR_DONE << 4;
+       if ((reg >> DPRX_RX_STATUS_SYM_LOCK(0)) & 1)
+               res |= DP_LANE_CHANNEL_EQ_DONE | DP_LANE_SYMBOL_LOCKED;
+       if ((reg >> DPRX_RX_STATUS_SYM_LOCK(1)) & 1)
+               res |= (DP_LANE_CHANNEL_EQ_DONE | DP_LANE_SYMBOL_LOCKED) << 4;
+
+       return res;
+}
+
+static u8 dprx_read_lane2_3_status(struct dprx *dprx)
+{
+       u32 reg;
+       u8 res = 0;
+
+       reg = dprx_read(dprx, DPRX_RX_STATUS);
+       if ((reg >> DPRX_RX_STATUS_CR_LOCK(2)) & 1)
+               res |= DP_LANE_CR_DONE;
+       if ((reg >> DPRX_RX_STATUS_CR_LOCK(3)) & 1)
+               res |= DP_LANE_CR_DONE << 4;
+       if ((reg >> DPRX_RX_STATUS_SYM_LOCK(2)) & 1)
+               res |= DP_LANE_CHANNEL_EQ_DONE | DP_LANE_SYMBOL_LOCKED;
+       if ((reg >> DPRX_RX_STATUS_SYM_LOCK(3)) & 1)
+               res |= (DP_LANE_CHANNEL_EQ_DONE | DP_LANE_SYMBOL_LOCKED) << 4;
+
+       return res;
+}
+
+static u8 dprx_read_lane_align_status(struct dprx *dprx)
+{
+       return (dprx_read(dprx, DPRX_RX_STATUS) >> 
DPRX_RX_STATUS_INTERLANE_ALIGN) & 1;
+}
+
+static u8 dprx_read_sink_status(struct dprx *dprx)
+{
+       return (dprx_read(dprx, DPRX_VBID(0)) >> DPRX_VBID_MSA_LOCK) & 1;
+}
+
+static u8 dprx_read_adjust_request(struct dprx *dprx,
+                                  struct dprx_training_control *ctl0,
+                                  struct dprx_training_control *ctl1)
+{
+       u8 next_volt_swing0;
+       u8 next_pre_emph0;
+       u8 next_volt_swing1;
+       u8 next_pre_emph1;
+
+       if (dprx_adjust_needed(dprx)) {
+               dprx_training_control_next(ctl0, &next_volt_swing0, 
&next_pre_emph0);
+               dprx_training_control_next(ctl1, &next_volt_swing1, 
&next_pre_emph1);
+       } else {
+               next_volt_swing0 = ctl0->volt_swing;
+               next_pre_emph0 = ctl0->pre_emph;
+               next_volt_swing1 = ctl1->volt_swing;
+               next_pre_emph1 = ctl1->pre_emph;
+       }
+
+       return next_volt_swing0 << DP_ADJUST_VOLTAGE_SWING_LANE0_SHIFT |
+              next_pre_emph0   << DP_ADJUST_PRE_EMPHASIS_LANE0_SHIFT  |
+              next_volt_swing1 << DP_ADJUST_VOLTAGE_SWING_LANE1_SHIFT |
+              next_pre_emph1   << DP_ADJUST_PRE_EMPHASIS_LANE1_SHIFT;
+}
+
+static u8 dprx_read_adjust_request_lane0_1(struct dprx *dprx)
+{
+       return dprx_read_adjust_request(dprx,
+                                       &dprx->training_control[0],
+                                       &dprx->training_control[1]);
+}
+
+static u8 dprx_read_adjust_request_lane2_3(struct dprx *dprx)
+{
+       return dprx_read_adjust_request(dprx,
+                                       &dprx->training_control[2],
+                                       &dprx->training_control[3]);
+}
+
+static u8 dprx_read_payload_table_update_status(struct dprx *dprx)
+{
+       u32 reg;
+       u32 act_handled;
+       u8 result = 0;
+
+       reg = dprx_read(dprx, DPRX_MST_STATUS1);
+       act_handled = (reg >> DPRX_MST_STATUS1_VCPTAB_ACT_ACK) & 1;
+
+       if (dprx->payload_table_updated)
+               result |= DP_PAYLOAD_TABLE_UPDATED;
+       if (act_handled)
+               result |= DP_PAYLOAD_ACT_HANDLED;
+
+       return result;
+}
+
+static void dprx_write_payload_table_update_status(struct dprx *dprx, u8 val)
+{
+       u32 reg;
+
+       if (val & DP_PAYLOAD_TABLE_UPDATED) {
+               dprx->payload_table_updated = 0;
+               reg = dprx_read(dprx, DPRX_MST_CONTROL1);
+               reg &= ~(1 << DPRX_MST_CONTROL1_VCPTAB_UPD_REQ);
+               dprx_write(dprx, DPRX_MST_CONTROL1, reg);
+       }
+}
+
+static u8 dprx_read_vc_payload_id_slot(struct dprx *dprx, u32 offset)
+{
+       return dprx->payload_table[offset + 1];
+}
+
+static u8 dprx_read_down_req(struct dprx *dprx, u32 offset)
+{
+       return dprx->down_req_buf[offset];
+}
+
+static void dprx_write_down_req(struct dprx *dprx, u32 offset, u8 val)
+{
+       struct sideband_msg msg;
+
+       dprx->down_req_buf[offset] = val;
+       if (dprx_decode_sideband_msg(&msg, dprx->down_req_buf, offset + 1))
+               dprx_handle_sideband_msg(dprx, &msg);
+}
+
+static u8 dprx_read_down_rep(struct dprx *dprx, u32 offset)
+{
+       return dprx->down_rep_buf[offset];
+}
+
+struct dprx_dpcd_handler {
+       u32 addr;
+       u32 range_len;
+       union {
+               u8 (*point)(struct dprx *dprx);
+               u8 (*range)(struct dprx *dprx, u32 offset);
+       } read;
+       union {
+               void (*point)(struct dprx *dprx, u8 val);
+               void (*range)(struct dprx *dprx, u32 offset, u8 val);
+       } write;
+};
+
+static void dprx_write_noop(struct dprx *dprx, u8 val)
+{
+}
+
+static void dprx_write_noop_range(struct dprx *dprx, u32 offset, u8 val)
+{
+}
+
+static struct dprx_dpcd_handler dprx_dpcd_handlers[] = {
+       { 0x00000, 16,  { .range = dprx_read_caps },
+                       { .range = dprx_write_noop_range } },
+       { 0x00021, 0,   { .point = dprx_read_mstm_cap },
+                       { .point = dprx_write_noop } },
+       { 0x00030, 16,  { .range = dprx_read_guid },
+                       { .range = dprx_write_guid } },
+       { 0x00100, 0,   { .point = dprx_read_link_bw },
+                       { .point = dprx_write_link_bw } },
+       { 0x00101, 0,   { .point = dprx_read_lane_count },
+                       { .point = dprx_write_lane_count } },
+       { 0x00102, 0,   { .point = dprx_read_training_pattern },
+                       { .point = dprx_write_training_pattern } },
+       { 0x00103, 4,   { .range = dprx_read_training_lane },
+                       { .range = dprx_write_training_lane } },
+       { 0x00111, 0,   { .point = dprx_read_mstm_ctrl },
+                       { .point = dprx_write_mstm_ctrl } },
+       { 0x001c0, 0,   { .point = dprx_read_payload_allocate_set },
+                       { .point = dprx_write_payload_allocate_set } },
+       { 0x001c1, 0,   { .point = dprx_read_payload_allocate_start_time_slot },
+                       { .point = dprx_write_payload_allocate_start_time_slot 
} },
+       { 0x001c2, 0,   { .point = dprx_read_payload_allocate_time_slot_count },
+                       { .point = dprx_write_payload_allocate_time_slot_count 
} },
+       { 0x00200, 0,   { .point = dprx_read_sink_count },
+                       { .point = dprx_write_noop } },
+       { 0x00201, 0,   { .point = dprx_read_device_service_irq_vector },
+                       { .point = dprx_write_device_service_irq_vector } },
+       { 0x00202, 0,   { .point = dprx_read_lane0_1_status },
+                       { .point = dprx_write_noop } },
+       { 0x00203, 0,   { .point = dprx_read_lane2_3_status },
+                       { .point = dprx_write_noop } },
+       { 0x00204, 0,   { .point = dprx_read_lane_align_status },
+                       { .point = dprx_write_noop } },
+       { 0x00205, 0,   { .point = dprx_read_sink_status },
+                       { .point = dprx_write_noop } },
+       { 0x00206, 0,   { .point = dprx_read_adjust_request_lane0_1 },
+                       { .point = dprx_write_noop } },
+       { 0x00207, 0,   { .point = dprx_read_adjust_request_lane2_3 },
+                       { .point = dprx_write_noop } },
+       { 0x002c0, 0,   { .point = dprx_read_payload_table_update_status },
+                       { .point = dprx_write_payload_table_update_status } },
+       { 0x002c1, 63,  { .range = dprx_read_vc_payload_id_slot },
+                       { .range = dprx_write_noop_range } },
+       { 0x01000, 48,  { .range = dprx_read_down_req },
+                       { .range = dprx_write_down_req } },
+       { 0x01400, 48,  { .range = dprx_read_down_rep },
+                       { .range = dprx_write_noop_range } },
+       /* Event Status Indicator is a copy of 200h - 205h */
+       { 0x02002, 0,   { .point = dprx_read_sink_count },
+                       { .point = dprx_write_noop } },
+       { 0x02003, 0,   { .point = dprx_read_device_service_irq_vector },
+                       { .point = dprx_write_device_service_irq_vector } },
+       { 0x0200c, 0,   { .point = dprx_read_lane0_1_status },
+                       { .point = dprx_write_noop } },
+       { 0x0200d, 0,   { .point = dprx_read_lane2_3_status },
+                       { .point = dprx_write_noop } },
+       { 0x0200e, 0,   { .point = dprx_read_lane_align_status },
+                       { .point = dprx_write_noop } },
+       { 0x0200f, 0,   { .point = dprx_read_sink_status },
+                       { .point = dprx_write_noop } },
+       /* Extended Receiver Capability is a copy of 0h - 0fh */
+       { 0x02200, 16,  { .range = dprx_read_caps },
+                       { .range = dprx_write_noop_range } },
+};
+
+static bool dprx_dpcd_handler_match(struct dprx_dpcd_handler *handler, u32 
addr)
+{
+       if (handler->range_len == 0)
+               return addr == handler->addr;
+       else
+               return addr >= handler->addr && addr < handler->addr + 
handler->range_len;
+}
+
+static void dprx_dpcd_handler_run(struct dprx_dpcd_handler *handler,
+                                 struct dprx *dprx, u32 addr, u8 *val, bool 
read)
+{
+       if (read) {
+               if (handler->range_len == 0)
+                       *val = handler->read.point(dprx);
+               else
+                       *val = handler->read.range(dprx, addr - handler->addr);
+       } else {
+               if (handler->range_len == 0)
+                       handler->write.point(dprx, *val);
+               else
+                       handler->write.range(dprx, addr - handler->addr, *val);
+       }
+}
+
+static void dprx_dpcd_access(struct dprx *dprx, u32 addr, u8 *val, bool read)
+{
+       struct dprx_dpcd_handler *handler;
+       int i;
+
+       for (i = 0; i < ARRAY_SIZE(dprx_dpcd_handlers); i++) {
+               handler = &dprx_dpcd_handlers[i];
+               if (dprx_dpcd_handler_match(handler, addr)) {
+                       dprx_dpcd_handler_run(handler, dprx, addr, val, read);
+                       return;
+               }
+       }
+
+       /* for unsupported registers, writes are ignored and reads return 0. */
+       if (read)
+               *val = 0;
+}
+
+static void dprx_handle_native_aux(struct dprx *dprx, struct aux_msg *req, 
struct aux_msg *rep)
+{
+       bool read = req->cmd & 1;
+       u8 *data;
+       int i;
+
+       rep->cmd = DP_AUX_NATIVE_REPLY_ACK;
+       if (read) {
+               rep->len = req->len;
+               data = rep->data;
+       } else {
+               rep->len = 0;
+               data = req->data;
+       }
+
+       for (i = 0; i < req->len; i++)
+               dprx_dpcd_access(dprx, req->addr + i, data + i, read);
+}
+
+static void dprx_handle_i2c_read(struct dprx *dprx, struct aux_msg *req, 
struct aux_msg *rep)
+{
+       int res;
+
+       res = dprx_i2c_read(&dprx->sinks[0], req->addr, rep->data, req->len);
+       if (!res) {
+               rep->cmd = DP_AUX_I2C_REPLY_ACK;
+               rep->len = req->len;
+       } else {
+               rep->cmd = DP_AUX_I2C_REPLY_NACK;
+               rep->len = 0;
+       }
+}
+
+static void dprx_handle_i2c_write(struct dprx *dprx, struct aux_msg *req, 
struct aux_msg *rep)
+{
+       int res;
+
+       res = dprx_i2c_write(&dprx->sinks[0], req->addr, req->data, req->len);
+       if (!res)
+               rep->cmd = DP_AUX_I2C_REPLY_ACK;
+       else
+               rep->cmd = DP_AUX_I2C_REPLY_NACK;
+       rep->len = 0;
+}
+
+static void dprx_decode_aux_request(struct aux_msg *req, struct aux_buf *buf)
+{
+       req->cmd = buf->data[0] >> 4;
+       req->addr = (buf->data[0] & 0xf) << 16 | buf->data[1] << 8 | 
buf->data[2];
+       if (buf->len < 4) {
+               req->len = 0;
+       } else {
+               req->len = buf->data[3] + 1;
+               memcpy(req->data, &buf->data[4], req->len);
+       }
+}
+
+static void dprx_encode_aux_reply(struct aux_msg *rep, struct aux_buf *buf)
+{
+       buf->data[0] = rep->cmd << 4;
+       memcpy(&buf->data[1], rep->data, rep->len);
+       buf->len = rep->len + 1;
+}
+
+static void dprx_handle_aux(struct dprx *dprx, struct aux_buf *req_buf, struct 
aux_buf *rep_buf)
+{
+       struct aux_msg req;
+       struct aux_msg rep;
+
+       dprx_decode_aux_request(&req, req_buf);
+
+       if (req.cmd & 8) {
+               dprx_handle_native_aux(dprx, &req, &rep);
+       } else {
+               if (req.cmd & 1)
+                       dprx_handle_i2c_read(dprx, &req, &rep);
+               else
+                       dprx_handle_i2c_write(dprx, &req, &rep);
+               if (!(req.cmd & DP_AUX_I2C_MOT))
+                       dprx_i2c_stop(&dprx->sinks[0]);
+       }
+
+       dprx_encode_aux_reply(&rep, rep_buf);
+}
+
+static int dprx_read_aux(struct dprx *dprx, struct aux_buf *buf)
+{
+       u32 control = dprx_read(dprx, DPRX_AUX_CONTROL);
+       int i;
+
+       /* check MSG_READY */
+       if (!((dprx_read(dprx, DPRX_AUX_STATUS) >> DPRX_AUX_STATUS_MSG_READY) & 
1))
+               return -1;
+
+       /* read LENGTH */
+       buf->len = (control >> DPRX_AUX_CONTROL_LENGTH_SHIFT) & 
DPRX_AUX_CONTROL_LENGTH_MASK;
+       if (buf->len > 20)
+               buf->len = 20;
+
+       /* read request */
+       for (i = 0; i < buf->len; i++)
+               buf->data[i] = dprx_read(dprx, DPRX_AUX_COMMAND + i);
+
+       return 0;
+}
+
+static void dprx_write_aux(struct dprx *dprx, struct aux_buf *buf)
+{
+       u32 reg;
+       int i;
+
+       if (!((dprx_read(dprx, DPRX_AUX_STATUS) >> DPRX_AUX_STATUS_READY_TO_TX) 
& 1))
+               return;
+
+       if (buf->len > 17)
+               buf->len = 17;
+       for (i = 0; i < buf->len; i++)
+               dprx_write(dprx, DPRX_AUX_COMMAND + i, buf->data[i]);
+
+       reg = dprx_read(dprx, DPRX_AUX_CONTROL);
+       reg &= ~(DPRX_AUX_CONTROL_LENGTH_MASK << DPRX_AUX_CONTROL_LENGTH_SHIFT);
+       reg |= buf->len << DPRX_AUX_CONTROL_LENGTH_SHIFT;
+       reg |= 1 << DPRX_AUX_CONTROL_TX_STROBE;
+       dprx_write(dprx, DPRX_AUX_CONTROL, reg);
+}
+
+static irqreturn_t dprx_isr(int irq, void *data)
+{
+       struct dprx *dprx = data;
+       struct aux_buf request;
+       struct aux_buf reply;
+
+       if (!dprx_read_aux(dprx, &request)) {
+               spin_lock(&dprx->lock);
+               dprx_handle_aux(dprx, &request, &reply);
+               spin_unlock(&dprx->lock);
+               dprx_write_aux(dprx, &reply);
+       }
+
+       return IRQ_HANDLED;
+}
+
+static void dprx_reset_hw(struct dprx *dprx)
+{
+       int i;
+
+       /* set link rate to 1.62 Gbps and lane count to 1 */
+       dprx_write(dprx, DPRX_RX_CONTROL,
+                  DP_LINK_BW_1_62 << DPRX_RX_CONTROL_LINK_RATE_SHIFT |
+                  1 << DPRX_RX_CONTROL_RECONFIG_LINKRATE |
+                  DPRX_RX_CONTROL_CHANNEL_CODING_8B10B << 
DPRX_RX_CONTROL_CHANNEL_CODING_SHIFT |
+                  1 << DPRX_RX_CONTROL_LANE_COUNT_SHIFT);
+       /* clear VC payload ID table */
+       for (i = 0; i < 8; i++)
+               dprx_write(dprx, DPRX_MST_VCPTAB(i), 0);
+       dprx_write(dprx, DPRX_MST_CONTROL1, 1 << 
DPRX_MST_CONTROL1_VCPTAB_UPD_FORCE);
+}
+
+static void dprx_reset(struct dprx *dprx)
+{
+       int i;
+
+       memset(dprx->guid, 0, sizeof(dprx->guid));
+       memset(dprx->training_control, 0, sizeof(dprx->training_control));
+
+       dprx->payload_allocate_set = 0;
+       dprx->payload_allocate_start_time_slot = 0;
+       dprx->payload_allocate_time_slot_count = 0;
+       memset(dprx->payload_table, 0, sizeof(dprx->payload_table));
+       dprx->payload_table_updated = 0;
+
+       memset(dprx->payload_id, 0, sizeof(dprx->payload_id));
+       memset(dprx->payload_pbn, 0, sizeof(dprx->payload_pbn));
+       dprx->payload_pbn_total = 0;
+
+       dprx->irq_vector = 0;
+
+       memset(dprx->down_req_buf, 0, sizeof(dprx->down_req_buf));
+       memset(dprx->down_rep_buf, 0, sizeof(dprx->down_rep_buf));
+
+       for (i = 0; i < 2; i++) {
+               dprx_msg_transaction_clear_rxbuf(&dprx->mt_rxbuf[i]);
+               dprx_msg_transaction_clear_txbuf(&dprx->mt_txbuf[i]);
+       }
+       dprx->mt_seqno = 0;
+       dprx->mt_pending = false;
+       dprx->down_rep_pending = false;
+
+       dprx_reset_hw(dprx);
+}
+
+#define to_dprx(sd) container_of(sd, struct dprx, subdev)
+
+static int dprx_get_edid(struct v4l2_subdev *sd, struct v4l2_edid *edid)
+{
+       struct dprx *dprx = to_dprx(sd);
+       struct dprx_sink *sink;
+       u32 end_block = edid->start_block + edid->blocks;
+       unsigned long flags;
+       int res = 0;
+
+       memset(edid->reserved, 0, sizeof(edid->reserved));
+
+       if (edid->pad >= dprx->max_stream_count)
+               return -EINVAL;
+
+       spin_lock_irqsave(&dprx->lock, flags);
+
+       sink = &dprx->sinks[edid->pad];
+       if (edid->start_block == 0 && edid->blocks == 0) {
+               edid->blocks = sink->blocks;
+               goto out;
+       }
+       if (sink->blocks == 0) {
+               res = -ENODATA;
+               goto out;
+       }
+       if (edid->start_block >= sink->blocks) {
+               res = -EINVAL;
+               goto out;
+       }
+       if (end_block > sink->blocks) {
+               end_block = sink->blocks;
+               edid->blocks = end_block - edid->start_block;
+       }
+
+       memcpy(edid->edid, sink->edid + edid->start_block * 128, edid->blocks * 
128);
+
+out:
+       spin_unlock_irqrestore(&dprx->lock, flags);
+
+       return res;
+}
+
+static int dprx_set_edid(struct v4l2_subdev *sd, struct v4l2_edid *edid)
+{
+       struct dprx *dprx = to_dprx(sd);
+       struct dprx_sink *sink;
+       bool prev_hpd;
+       bool cur_hpd;
+       unsigned long flags;
+
+       memset(edid->reserved, 0, sizeof(edid->reserved));
+
+       if (edid->pad >= dprx->max_stream_count)
+               return -EINVAL;
+       if (edid->start_block != 0)
+               return -EINVAL;
+       if (edid->blocks > DPRX_MAX_EDID_BLOCKS) {
+               edid->blocks = DPRX_MAX_EDID_BLOCKS;
+               return -E2BIG;
+       }
+
+       spin_lock_irqsave(&dprx->lock, flags);
+       sink = &dprx->sinks[edid->pad];
+       /*
+        * This is an MST DisplayPort device, which means that one HPD
+        * line controls all the video streams. The way this is handled
+        * in s_edid is that the HPD line is controlled by the presence
+        * of only the first stream's EDID. This allows, for example, to
+        * first set the second streams's EDID and then the first one in
+        * order to reduce the amount of AUX communication.
+        */
+       prev_hpd = dprx->sinks[0].blocks > 0;
+       sink->blocks = edid->blocks;
+       memcpy(sink->edid, edid->edid, edid->blocks * 128);
+       cur_hpd = dprx->sinks[0].blocks > 0;
+       if (!prev_hpd && cur_hpd)
+               dprx_reset(dprx);
+       spin_unlock_irqrestore(&dprx->lock, flags);
+
+       if (!prev_hpd && cur_hpd) {
+               dprx_set_hpd(dprx, 1);
+       } else if (prev_hpd && !cur_hpd) {
+               dprx_set_hpd(dprx, 0);
+       } else if (prev_hpd && cur_hpd) {
+               /* HPD replug - pulse for >2ms */
+               dprx_set_hpd(dprx, 0);
+               usleep_range(2000, 4000);
+               dprx_set_hpd(dprx, 1);
+       }
+
+       return 0;
+}
+
+static int dprx_query_dv_timings(struct v4l2_subdev *sd, unsigned int pad,
+                                struct v4l2_dv_timings *timings)
+{
+       struct dprx *dprx = to_dprx(sd);
+       u32 htotal, vtotal;
+       u32 hsp, hsw;
+       u32 hstart, vstart;
+       u32 vsp, vsw;
+       u32 hwidth, vheight;
+
+       if (pad >= dprx->max_stream_count)
+               return -EINVAL;
+
+       if (!((dprx_read(dprx, DPRX_VBID(pad)) >> DPRX_VBID_MSA_LOCK) & 1))
+               return -ENOLINK;
+
+       htotal  = dprx_read(dprx, DPRX_MSA_HTOTAL(pad));
+       vtotal  = dprx_read(dprx, DPRX_MSA_VTOTAL(pad));
+       hsp     = dprx_read(dprx, DPRX_MSA_HSP(pad));
+       hsw     = dprx_read(dprx, DPRX_MSA_HSW(pad));
+       hstart  = dprx_read(dprx, DPRX_MSA_HSTART(pad));
+       vstart  = dprx_read(dprx, DPRX_MSA_VSTART(pad));
+       vsp     = dprx_read(dprx, DPRX_MSA_VSP(pad));
+       vsw     = dprx_read(dprx, DPRX_MSA_VSW(pad));
+       hwidth  = dprx_read(dprx, DPRX_MSA_HWIDTH(pad));
+       vheight = dprx_read(dprx, DPRX_MSA_VHEIGHT(pad));
+
+       memset(timings, 0, sizeof(*timings));
+       timings->type = V4L2_DV_BT_656_1120;
+       timings->bt.width = hwidth;
+       timings->bt.height = vheight;
+       timings->bt.polarities = (!vsp) | (!hsp) << 1;
+       timings->bt.hfrontporch = htotal - hstart - hwidth;
+       timings->bt.hsync = hsw;
+       timings->bt.hbackporch = hstart - hsw;
+       timings->bt.vfrontporch = vtotal - vstart - vheight;
+       timings->bt.vsync = vsw;
+       timings->bt.vbackporch = vstart - vsw;
+
+       return 0;
+}
+
+/* DisplayPort 1.4 capabilities */
+
+static const struct v4l2_dv_timings_cap dprx_timings_cap = {
+       .type = V4L2_DV_BT_656_1120,
+       .bt = {
+               .min_width = 0,
+               .max_width = 7680,
+               .min_height = 0,
+               .max_height = 4320,
+               .min_pixelclock = 0,
+               .max_pixelclock = 1350000000, /* 8.1Gbps * 4lanes / 24bpp */
+               .standards = V4L2_DV_BT_STD_CEA861 | V4L2_DV_BT_STD_DMT |
+                       V4L2_DV_BT_STD_CVT | V4L2_DV_BT_STD_GTF,
+               .capabilities = V4L2_DV_BT_CAP_PROGRESSIVE |
+                       V4L2_DV_BT_CAP_REDUCED_BLANKING |
+                       V4L2_DV_BT_CAP_CUSTOM,
+       },
+};
+
+static int dprx_enum_dv_timings(struct v4l2_subdev *sd, struct 
v4l2_enum_dv_timings *timings)
+{
+       return v4l2_enum_dv_timings_cap(timings, &dprx_timings_cap,
+                                       NULL, NULL);
+}
+
+static int dprx_dv_timings_cap(struct v4l2_subdev *sd, struct 
v4l2_dv_timings_cap *cap)
+{
+       *cap = dprx_timings_cap;
+
+       return 0;
+}
+
+static const struct v4l2_subdev_pad_ops dprx_pad_ops = {
+       .get_edid = dprx_get_edid,
+       .set_edid = dprx_set_edid,
+       .dv_timings_cap = dprx_dv_timings_cap,
+       .enum_dv_timings = dprx_enum_dv_timings,
+       .query_dv_timings = dprx_query_dv_timings,
+};
+
+static const struct v4l2_subdev_ops dprx_subdev_ops = {
+       .pad = &dprx_pad_ops,
+};
+
+static const struct media_entity_operations dprx_entity_ops = {
+       .link_validate = v4l2_subdev_link_validate,
+       .get_fwnode_pad = v4l2_subdev_get_fwnode_pad_1_to_1,
+};
+
+static int dprx_init_pads(struct dprx *dprx)
+{
+       int i;
+
+       for (i = 0; i < dprx->max_stream_count; i++)
+               dprx->pads[i].flags = MEDIA_PAD_FL_SOURCE;
+
+       return media_entity_pads_init(&dprx->subdev.entity, 
dprx->max_stream_count, dprx->pads);
+}
+
+static int dprx_probe(struct platform_device *pdev)
+{
+       struct dprx *dprx;
+       int irq;
+       int res;
+
+       dprx = devm_kzalloc(&pdev->dev, sizeof(*dprx), GFP_KERNEL);
+       if (!dprx)
+               return -ENOMEM;
+       dprx->dev = &pdev->dev;
+       platform_set_drvdata(pdev, dprx);
+
+       dprx->iobase = devm_platform_ioremap_resource(pdev, 0);
+       if (IS_ERR(dprx->iobase))
+               return PTR_ERR(dprx->iobase);
+
+       irq = platform_get_irq(pdev, 0);
+       if (irq < 0)
+               return irq;
+
+       res = devm_request_irq(dprx->dev, irq, dprx_isr, 0, "intel-dprx", dprx);
+       if (res)
+               return res;
+
+       res = device_property_read_u32(&pdev->dev, "intel,max-link-rate", 
&dprx->max_link_rate);
+       if (res)
+               return res;
+
+       res = device_property_read_u32(&pdev->dev, "intel,max-lane-count", 
&dprx->max_lane_count);
+       if (res)
+               return res;
+
+       dprx->multi_stream_support = device_property_read_bool(&pdev->dev,
+                                                              
"intel,multi-stream-support");
+
+       if (dprx->multi_stream_support) {
+               res = device_property_read_u32(&pdev->dev, 
"intel,max-stream-count",
+                                              &dprx->max_stream_count);
+               if (res)
+                       return res;
+       } else {
+               dprx->max_stream_count = 1;
+       }
+
+       dprx_init_caps(dprx);
+
+       dprx->subdev.owner = THIS_MODULE;
+       dprx->subdev.dev = &pdev->dev;
+       v4l2_subdev_init(&dprx->subdev, &dprx_subdev_ops);
+       v4l2_set_subdevdata(&dprx->subdev, &pdev->dev);
+       snprintf(dprx->subdev.name, sizeof(dprx->subdev.name), "%s %s",
+                KBUILD_MODNAME, dev_name(&pdev->dev));
+       dprx->subdev.flags = V4L2_SUBDEV_FL_HAS_DEVNODE;
+
+       dprx->subdev.entity.function = MEDIA_ENT_F_PROC_VIDEO_PIXEL_FORMATTER;
+       dprx->subdev.entity.ops = &dprx_entity_ops;
+
+       res = dprx_init_pads(dprx);
+       if (res)
+               return res;
+
+       res = v4l2_async_register_subdev(&dprx->subdev);
+       if (res)
+               return res;
+
+       dprx_set_hpd(dprx, 0);
+       dprx_reset_hw(dprx);
+
+       dprx_set_irq(dprx, 1);
+
+       return 0;
+}
+
+static void dprx_remove(struct platform_device *pdev)
+{
+       struct dprx *dprx = platform_get_drvdata(pdev);
+
+       /* disable interrupts */
+       dprx_set_irq(dprx, 0);
+
+       v4l2_async_unregister_subdev(&dprx->subdev);
+}
+
+static const struct of_device_id dprx_match_table[] = {
+       { .compatible = "intel,dprx-20.0.1" },
+       { },
+};
+
+static struct platform_driver dprx_platform_driver = {
+       .probe = dprx_probe,
+       .remove_new = dprx_remove,
+       .driver = {
+               .name = "intel-dprx",
+               .of_match_table = dprx_match_table,
+       },
+};
+
+module_platform_driver(dprx_platform_driver);
+
+MODULE_AUTHOR("Paweł Anikiel <panik...@google.com>");
+MODULE_DESCRIPTION("Intel DisplayPort RX IP core driver");
+MODULE_LICENSE("GPL");
-- 
2.44.0.rc0.258.g7320e95886-goog

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