The drm_get_edid function should be used instead of drm_do_get_edid by
exposing the DDC bus as an I2C adapter. Implement this for A10s.

Signed-off-by: Jonathan Liu <net...@gmail.com>
---
 drivers/gpu/drm/sun4i/Makefile         |   1 +
 drivers/gpu/drm/sun4i/sun4i_hdmi.h     |  11 ++-
 drivers/gpu/drm/sun4i/sun4i_hdmi_enc.c |  96 +++----------------
 drivers/gpu/drm/sun4i/sun4i_hdmi_i2c.c | 166 +++++++++++++++++++++++++++++++++
 4 files changed, 190 insertions(+), 84 deletions(-)
 create mode 100644 drivers/gpu/drm/sun4i/sun4i_hdmi_i2c.c

diff --git a/drivers/gpu/drm/sun4i/Makefile b/drivers/gpu/drm/sun4i/Makefile
index e29fd3a2ba9c..43c753cafc88 100644
--- a/drivers/gpu/drm/sun4i/Makefile
+++ b/drivers/gpu/drm/sun4i/Makefile
@@ -2,6 +2,7 @@ sun4i-drm-y += sun4i_drv.o
 sun4i-drm-y += sun4i_framebuffer.o
 
 sun4i-drm-hdmi-y += sun4i_hdmi_enc.o
+sun4i-drm-hdmi-y += sun4i_hdmi_i2c.o
 sun4i-drm-hdmi-y += sun4i_hdmi_ddc_clk.o
 sun4i-drm-hdmi-y += sun4i_hdmi_tmds_clk.o
 
diff --git a/drivers/gpu/drm/sun4i/sun4i_hdmi.h 
b/drivers/gpu/drm/sun4i/sun4i_hdmi.h
index 2589bc92be59..8e7a70f67f04 100644
--- a/drivers/gpu/drm/sun4i/sun4i_hdmi.h
+++ b/drivers/gpu/drm/sun4i/sun4i_hdmi.h
@@ -100,6 +100,7 @@
 #define SUN4I_HDMI_DDC_CTRL_START_CMD          BIT(30)
 #define SUN4I_HDMI_DDC_CTRL_FIFO_DIR_MASK      BIT(8)
 #define SUN4I_HDMI_DDC_CTRL_FIFO_DIR_READ      (0 << 8)
+#define SUN4I_HDMI_DDC_CTRL_FIFO_DIR_WRITE     (1 << 8)
 #define SUN4I_HDMI_DDC_CTRL_RESET              BIT(0)
 
 #define SUN4I_HDMI_DDC_ADDR_REG                0x504
@@ -108,6 +109,10 @@
 #define SUN4I_HDMI_DDC_ADDR_OFFSET(off)                (((off) & 0xff) << 8)
 #define SUN4I_HDMI_DDC_ADDR_SLAVE(addr)                ((addr) & 0xff)
 
+#define SUN4I_HDMI_DDC_INTERRUPT_STATUS_REG    0x50c
+#define SUN4I_HDMI_DDC_INTERRUPT_STATUS_FIFO_REQUEST   BIT(4)
+#define SUN4I_HDMI_DDC_INTERRUPT_STATUS_TRANSFER_COMPLETE      BIT(0)
+
 #define SUN4I_HDMI_DDC_FIFO_CTRL_REG   0x510
 #define SUN4I_HDMI_DDC_FIFO_CTRL_CLEAR         BIT(31)
 
@@ -115,7 +120,8 @@
 #define SUN4I_HDMI_DDC_BYTE_COUNT_REG  0x51c
 
 #define SUN4I_HDMI_DDC_CMD_REG         0x520
-#define SUN4I_HDMI_DDC_CMD_EXPLICIT_EDDC_READ  6
+#define SUN4I_HDMI_DDC_CMD_IMPLICIT_WRITE      3
+#define SUN4I_HDMI_DDC_CMD_IMPLICIT_READ       5
 
 #define SUN4I_HDMI_DDC_CLK_REG         0x528
 #define SUN4I_HDMI_DDC_CLK_M(m)                        (((m) & 0x7) << 3)
@@ -181,6 +187,8 @@ struct sun4i_hdmi {
        struct clk              *ddc_clk;
        struct clk              *tmds_clk;
 
+       struct i2c_adapter      *i2c;
+
        struct sun4i_drv        *drv;
 
        bool                    hdmi_monitor;
@@ -192,5 +200,6 @@ int sun4i_ddc_create(struct sun4i_hdmi *hdmi, struct clk 
*clk);
 int sun6i_ddc_create(struct sun4i_hdmi *hdmi, struct clk *clk);
 int sun4i_tmds_create(struct sun4i_hdmi *hdmi);
 int sun6i_tmds_create(struct sun4i_hdmi *hdmi);
+int sun4i_hdmi_i2c_create(struct sun4i_hdmi *hdmi);
 
 #endif /* _SUN4I_HDMI_H_ */
diff --git a/drivers/gpu/drm/sun4i/sun4i_hdmi_enc.c 
b/drivers/gpu/drm/sun4i/sun4i_hdmi_enc.c
index e9abf93eb41c..6c9b11c4cf68 100644
--- a/drivers/gpu/drm/sun4i/sun4i_hdmi_enc.c
+++ b/drivers/gpu/drm/sun4i/sun4i_hdmi_enc.c
@@ -186,93 +186,13 @@ static const struct drm_encoder_funcs sun4i_hdmi_funcs = {
        .destroy        = drm_encoder_cleanup,
 };
 
-static int sun4i_hdmi_read_sub_block(struct sun4i_hdmi *hdmi,
-                                    unsigned int blk, unsigned int offset,
-                                    u8 *buf, unsigned int count)
-{
-       unsigned long reg;
-       int i;
-
-       reg = readl(hdmi->base + SUN4I_HDMI_DDC_CTRL_REG);
-       reg &= ~SUN4I_HDMI_DDC_CTRL_FIFO_DIR_MASK;
-       writel(reg | SUN4I_HDMI_DDC_CTRL_FIFO_DIR_READ,
-              hdmi->base + SUN4I_HDMI_DDC_CTRL_REG);
-
-       writel(SUN4I_HDMI_DDC_ADDR_SEGMENT(offset >> 8) |
-              SUN4I_HDMI_DDC_ADDR_EDDC(DDC_SEGMENT_ADDR << 1) |
-              SUN4I_HDMI_DDC_ADDR_OFFSET(offset) |
-              SUN4I_HDMI_DDC_ADDR_SLAVE(DDC_ADDR),
-              hdmi->base + SUN4I_HDMI_DDC_ADDR_REG);
-
-       reg = readl(hdmi->base + SUN4I_HDMI_DDC_FIFO_CTRL_REG);
-       writel(reg | SUN4I_HDMI_DDC_FIFO_CTRL_CLEAR,
-              hdmi->base + SUN4I_HDMI_DDC_FIFO_CTRL_REG);
-
-       writel(count, hdmi->base + SUN4I_HDMI_DDC_BYTE_COUNT_REG);
-       writel(SUN4I_HDMI_DDC_CMD_EXPLICIT_EDDC_READ,
-              hdmi->base + SUN4I_HDMI_DDC_CMD_REG);
-
-       reg = readl(hdmi->base + SUN4I_HDMI_DDC_CTRL_REG);
-       writel(reg | SUN4I_HDMI_DDC_CTRL_START_CMD,
-              hdmi->base + SUN4I_HDMI_DDC_CTRL_REG);
-
-       if (readl_poll_timeout(hdmi->base + SUN4I_HDMI_DDC_CTRL_REG, reg,
-                              !(reg & SUN4I_HDMI_DDC_CTRL_START_CMD),
-                              100, 100000))
-               return -EIO;
-
-       for (i = 0; i < count; i++)
-               buf[i] = readb(hdmi->base + SUN4I_HDMI_DDC_FIFO_DATA_REG);
-
-       return 0;
-}
-
-static int sun4i_hdmi_read_edid_block(void *data, u8 *buf, unsigned int blk,
-                                     size_t length)
-{
-       struct sun4i_hdmi *hdmi = data;
-       int retry = 2, i;
-
-       do {
-               for (i = 0; i < length; i += SUN4I_HDMI_DDC_FIFO_SIZE) {
-                       unsigned char offset = blk * EDID_LENGTH + i;
-                       unsigned int count = min((unsigned 
int)SUN4I_HDMI_DDC_FIFO_SIZE,
-                                                length - i);
-                       int ret;
-
-                       ret = sun4i_hdmi_read_sub_block(hdmi, blk, offset,
-                                                       buf + i, count);
-                       if (ret)
-                               return ret;
-               }
-       } while (!drm_edid_block_valid(buf, blk, true, NULL) && (retry--));
-
-       return 0;
-}
-
 static int sun4i_hdmi_get_modes(struct drm_connector *connector)
 {
        struct sun4i_hdmi *hdmi = drm_connector_to_sun4i_hdmi(connector);
-       unsigned long reg;
        struct edid *edid;
        int ret;
 
-       /* Reset i2c controller */
-       writel(SUN4I_HDMI_DDC_CTRL_ENABLE | SUN4I_HDMI_DDC_CTRL_RESET,
-              hdmi->base + SUN4I_HDMI_DDC_CTRL_REG);
-       if (readl_poll_timeout(hdmi->base + SUN4I_HDMI_DDC_CTRL_REG, reg,
-                              !(reg & SUN4I_HDMI_DDC_CTRL_RESET),
-                              100, 2000))
-               return -EIO;
-
-       writel(SUN4I_HDMI_DDC_LINE_CTRL_SDA_ENABLE |
-              SUN4I_HDMI_DDC_LINE_CTRL_SCL_ENABLE,
-              hdmi->base + SUN4I_HDMI_DDC_LINE_CTRL_REG);
-
-       clk_prepare_enable(hdmi->ddc_clk);
-       clk_set_rate(hdmi->ddc_clk, 100000);
-
-       edid = drm_do_get_edid(connector, sun4i_hdmi_read_edid_block, hdmi);
+       edid = drm_get_edid(connector, hdmi->i2c);
        if (!edid)
                return 0;
 
@@ -284,8 +204,6 @@ static int sun4i_hdmi_get_modes(struct drm_connector 
*connector)
        ret = drm_add_edid_modes(connector, edid);
        kfree(edid);
 
-       clk_disable_unprepare(hdmi->ddc_clk);
-
        return ret;
 }
 
@@ -424,6 +342,7 @@ struct sun4i_hdmi_variant {
        const struct drm_connector_helper_funcs *connector_helpers;
        int (*ddc_create)(struct sun4i_hdmi *hdmi, struct clk *clk);
        int (*tmds_create)(struct sun4i_hdmi *hdmi);
+       int (*hdmi_i2c_create)(struct sun4i_hdmi *hdmi);
        bool has_ddc_parent_clk;
        bool has_reset_control;
 
@@ -439,6 +358,7 @@ static const struct sun4i_hdmi_variant sun5i_variant = {
        .connector_helpers      = &sun4i_hdmi_connector_helper_funcs,
        .ddc_create             = sun4i_ddc_create,
        .tmds_create            = sun4i_tmds_create,
+       .hdmi_i2c_create        = sun4i_hdmi_i2c_create,
        .has_ddc_parent_clk     = false,
        .has_reset_control      = false,
        .pad_ctrl0_init_val     = SUN4I_HDMI_PAD_CTRL0_TXEN |
@@ -622,6 +542,14 @@ static int sun4i_hdmi_bind(struct device *dev, struct 
device *master,
                goto err_disable_mod_clk;
        }
 
+       if (hdmi->variant->hdmi_i2c_create) {
+               ret = hdmi->variant->hdmi_i2c_create(hdmi);
+               if (ret) {
+                       dev_err(dev, "Couldn't create the HDMI I2C adapter\n");
+                       goto err_disable_mod_clk;
+               }
+       }
+
        drm_encoder_helper_add(&hdmi->encoder,
                               &sun4i_hdmi_helper_funcs);
        ret = drm_encoder_init(drm,
@@ -676,6 +604,8 @@ static void sun4i_hdmi_unbind(struct device *dev, struct 
device *master,
 
        drm_connector_cleanup(&hdmi->connector);
        drm_encoder_cleanup(&hdmi->encoder);
+       if (hdmi->i2c)
+               i2c_del_adapter(hdmi->i2c);
        clk_disable_unprepare(hdmi->mod_clk);
        clk_disable_unprepare(hdmi->bus_clk);
 }
diff --git a/drivers/gpu/drm/sun4i/sun4i_hdmi_i2c.c 
b/drivers/gpu/drm/sun4i/sun4i_hdmi_i2c.c
new file mode 100644
index 000000000000..c33fa13cc668
--- /dev/null
+++ b/drivers/gpu/drm/sun4i/sun4i_hdmi_i2c.c
@@ -0,0 +1,166 @@
+/*
+ * Copyright (C) 2017 Jonathan Liu
+ *
+ * Jonathan Liu <net...@gmail.com>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of
+ * the License, or (at your option) any later version.
+ */
+
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/errno.h>
+#include <linux/clk.h>
+#include <linux/i2c.h>
+#include <linux/iopoll.h>
+
+#include "sun4i_hdmi.h"
+
+static int xfer_msg_chunk(struct sun4i_hdmi *hdmi, struct i2c_msg *msg)
+{
+       u32 count = min_t(u32, msg->len, SUN4I_HDMI_DDC_FIFO_SIZE);
+       u32 reg;
+       int i;
+
+       reg = readl(hdmi->base + SUN4I_HDMI_DDC_FIFO_CTRL_REG);
+       writel(reg | SUN4I_HDMI_DDC_FIFO_CTRL_CLEAR,
+              hdmi->base + SUN4I_HDMI_DDC_FIFO_CTRL_REG);
+
+       writel(count, hdmi->base
+              + SUN4I_HDMI_DDC_BYTE_COUNT_REG);
+       writel(msg->flags & I2C_M_RD
+              ? SUN4I_HDMI_DDC_CMD_IMPLICIT_READ
+              : SUN4I_HDMI_DDC_CMD_IMPLICIT_WRITE,
+              hdmi->base + SUN4I_HDMI_DDC_CMD_REG);
+
+       reg = readl(hdmi->base + SUN4I_HDMI_DDC_CTRL_REG);
+       writel(reg | SUN4I_HDMI_DDC_CTRL_START_CMD,
+              hdmi->base + SUN4I_HDMI_DDC_CTRL_REG);
+
+       if (!(msg->flags & I2C_M_RD)) {
+               for (i = 0; i < count; i++) {
+                       writeb(*msg->buf++, hdmi->base
+                              + SUN4I_HDMI_DDC_FIFO_DATA_REG);
+                       --msg->len;
+               }
+       }
+
+       if (readl_poll_timeout(hdmi->base + SUN4I_HDMI_DDC_CTRL_REG,
+                              reg,
+                              !(reg & SUN4I_HDMI_DDC_CTRL_START_CMD),
+                              100, 100000))
+               return -EIO;
+
+       reg = readl(hdmi->base + SUN4I_HDMI_DDC_INTERRUPT_STATUS_REG);
+       reg &= ~SUN4I_HDMI_DDC_INTERRUPT_STATUS_FIFO_REQUEST;
+
+       if (reg != SUN4I_HDMI_DDC_INTERRUPT_STATUS_TRANSFER_COMPLETE)
+               return -EIO;
+
+       if (msg->flags & I2C_M_RD) {
+               for (i = 0; i < count; i++) {
+                       *msg->buf++ = readb(hdmi->base
+                                           + SUN4I_HDMI_DDC_FIFO_DATA_REG);
+                       --msg->len;
+               }
+       }
+
+       return 0;
+}
+
+static int xfer_msg(struct sun4i_hdmi *hdmi, struct i2c_msg *msg)
+{
+       u32 reg;
+       int ret;
+
+       if (!msg->len)
+               return -EIO;
+
+       while (msg->len) {
+               reg = readl(hdmi->base + SUN4I_HDMI_DDC_CTRL_REG);
+               reg &= ~SUN4I_HDMI_DDC_CTRL_FIFO_DIR_MASK;
+
+               writel(reg | (msg->flags & I2C_M_RD
+                             ? SUN4I_HDMI_DDC_CTRL_FIFO_DIR_READ
+                             : SUN4I_HDMI_DDC_CTRL_FIFO_DIR_WRITE),
+                      hdmi->base + SUN4I_HDMI_DDC_CTRL_REG);
+
+               writel(SUN4I_HDMI_DDC_ADDR_SLAVE(msg->addr),
+                      hdmi->base + SUN4I_HDMI_DDC_ADDR_REG);
+
+               ret = xfer_msg_chunk(hdmi, msg);
+               if (ret)
+                       return ret;
+       }
+
+       return 0;
+}
+
+static int sun4i_hdmi_i2c_xfer(struct i2c_adapter *adap,
+                              struct i2c_msg *msgs, int num)
+{
+       struct sun4i_hdmi *hdmi = i2c_get_adapdata(adap);
+       u32 reg;
+       int err, ret = num;
+       int i;
+
+       /* Reset i2c controller */
+       writel(SUN4I_HDMI_DDC_CTRL_ENABLE | SUN4I_HDMI_DDC_CTRL_RESET,
+              hdmi->base + SUN4I_HDMI_DDC_CTRL_REG);
+       if (readl_poll_timeout(hdmi->base + SUN4I_HDMI_DDC_CTRL_REG, reg,
+                              !(reg & SUN4I_HDMI_DDC_CTRL_RESET),
+                              100, 2000))
+               return -EIO;
+
+       writel(SUN4I_HDMI_DDC_LINE_CTRL_SDA_ENABLE |
+              SUN4I_HDMI_DDC_LINE_CTRL_SCL_ENABLE,
+              hdmi->base + SUN4I_HDMI_DDC_LINE_CTRL_REG);
+
+       clk_prepare_enable(hdmi->ddc_clk);
+       clk_set_rate(hdmi->ddc_clk, 100000);
+
+       for (i = 0; i < num; i++) {
+               err = xfer_msg(hdmi, &msgs[i]);
+               if (err) {
+                       ret = err;
+                       break;
+               }
+       }
+
+       clk_disable_unprepare(hdmi->ddc_clk);
+       return ret;
+}
+
+static u32 sun4i_hdmi_i2c_func(struct i2c_adapter *adap)
+{
+       return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
+}
+
+static const struct i2c_algorithm sun4i_hdmi_i2c_algorithm = {
+       .master_xfer    = sun4i_hdmi_i2c_xfer,
+       .functionality  = sun4i_hdmi_i2c_func,
+};
+
+static struct i2c_adapter sun4i_hdmi_i2c_adapter = {
+       .owner  = THIS_MODULE,
+       .class  = I2C_CLASS_DDC,
+       .algo   = &sun4i_hdmi_i2c_algorithm,
+       .name   = "sun4i_hdmi_i2c adapter",
+};
+
+int sun4i_hdmi_i2c_create(struct sun4i_hdmi *hdmi)
+{
+       int ret = 0;
+
+       i2c_set_adapdata(&sun4i_hdmi_i2c_adapter, hdmi);
+
+       ret = i2c_add_adapter(&sun4i_hdmi_i2c_adapter);
+       if (ret)
+               return ret;
+
+       hdmi->i2c = &sun4i_hdmi_i2c_adapter;
+
+       return ret;
+}
-- 
2.12.2

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