This patch adds the usb driver source file most_usb.c and
modifies the Makefile and Kconfig accordingly.

Signed-off-by: Christian Gromm <christian.gr...@microchip.com>
---
v2:
Reported-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>
        - don't remove usb driver from staging area
        - don't touch staging/most/Kconfig
        - remove subdirectory for USB driver and put source file into
          drivers/most
v3:
        - submitted fixes found during code audit to staging version
          first to be able to resend single patch that adds the driver
v4:
Reported-by: Dan Carpenter <dan.carpen...@oracle.com>
        
        submitted patch set that fixes issues found during code audit
        to staging version first to be able to resend single patch that
        adds the driver. The patch series included:

        - use function sysfs_streq
        - add missing put_device calls
        - use correct error codes
        - replace code to calculate array index
        - don't use error path to exit function on success
        - move allocation of URB out of critical section
        - return 0 instead of variable
        - change return value of function drci_rd_reg
        - don't use expressions that might fail in a declaration
        - change order of function parameters

v5:
Reported-by: Dan Carpenter <dan.carpen...@oracle.com>
        
        submitted patch set that fixes issues found during code audit
        to staging version first to be able to resend single patch that
        adds the driver. The patch series included:

        - init return value in default path of switch/case expression

 drivers/most/Kconfig    |   12 +
 drivers/most/Makefile   |    2 +
 drivers/most/most_usb.c | 1170 +++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 1184 insertions(+)
 create mode 100644 drivers/most/most_usb.c

diff --git a/drivers/most/Kconfig b/drivers/most/Kconfig
index 58d7999..7b65320 100644
--- a/drivers/most/Kconfig
+++ b/drivers/most/Kconfig
@@ -13,3 +13,15 @@ menuconfig MOST
          module will be called most_core.
 
          If in doubt, say N here.
+
+if MOST
+config MOST_USB_HDM
+       tristate "USB"
+       depends on USB && NET
+       help
+         Say Y here if you want to connect via USB to network transceiver.
+         This device driver depends on the networking AIM.
+
+         To compile this driver as a module, choose M here: the
+         module will be called most_usb.
+endif
diff --git a/drivers/most/Makefile b/drivers/most/Makefile
index e810cd3..6a3cb90 100644
--- a/drivers/most/Makefile
+++ b/drivers/most/Makefile
@@ -2,3 +2,5 @@
 obj-$(CONFIG_MOST) += most_core.o
 most_core-y := core.o \
                configfs.o
+
+obj-$(CONFIG_MOST_USB_HDM) += most_usb.o
diff --git a/drivers/most/most_usb.c b/drivers/most/most_usb.c
new file mode 100644
index 0000000..2640c5b
--- /dev/null
+++ b/drivers/most/most_usb.c
@@ -0,0 +1,1170 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * usb.c - Hardware dependent module for USB
+ *
+ * Copyright (C) 2013-2015 Microchip Technology Germany II GmbH & Co. KG
+ */
+
+#include <linux/module.h>
+#include <linux/fs.h>
+#include <linux/usb.h>
+#include <linux/slab.h>
+#include <linux/init.h>
+#include <linux/cdev.h>
+#include <linux/device.h>
+#include <linux/list.h>
+#include <linux/completion.h>
+#include <linux/mutex.h>
+#include <linux/spinlock.h>
+#include <linux/interrupt.h>
+#include <linux/workqueue.h>
+#include <linux/sysfs.h>
+#include <linux/dma-mapping.h>
+#include <linux/etherdevice.h>
+#include <linux/uaccess.h>
+#include <linux/most.h>
+
+#define USB_MTU                        512
+#define NO_ISOCHRONOUS_URB     0
+#define AV_PACKETS_PER_XACT    2
+#define BUF_CHAIN_SIZE         0xFFFF
+#define MAX_NUM_ENDPOINTS      30
+#define MAX_SUFFIX_LEN         10
+#define MAX_STRING_LEN         80
+#define MAX_BUF_SIZE           0xFFFF
+
+#define USB_VENDOR_ID_SMSC     0x0424  /* VID: SMSC */
+#define USB_DEV_ID_BRDG                0xC001  /* PID: USB Bridge */
+#define USB_DEV_ID_OS81118     0xCF18  /* PID: USB OS81118 */
+#define USB_DEV_ID_OS81119     0xCF19  /* PID: USB OS81119 */
+#define USB_DEV_ID_OS81210     0xCF30  /* PID: USB OS81210 */
+/* DRCI Addresses */
+#define DRCI_REG_NI_STATE      0x0100
+#define DRCI_REG_PACKET_BW     0x0101
+#define DRCI_REG_NODE_ADDR     0x0102
+#define DRCI_REG_NODE_POS      0x0103
+#define DRCI_REG_MEP_FILTER    0x0140
+#define DRCI_REG_HASH_TBL0     0x0141
+#define DRCI_REG_HASH_TBL1     0x0142
+#define DRCI_REG_HASH_TBL2     0x0143
+#define DRCI_REG_HASH_TBL3     0x0144
+#define DRCI_REG_HW_ADDR_HI    0x0145
+#define DRCI_REG_HW_ADDR_MI    0x0146
+#define DRCI_REG_HW_ADDR_LO    0x0147
+#define DRCI_REG_BASE          0x1100
+#define DRCI_COMMAND           0x02
+#define DRCI_READ_REQ          0xA0
+#define DRCI_WRITE_REQ         0xA1
+
+/**
+ * struct most_dci_obj - Direct Communication Interface
+ * @kobj:position in sysfs
+ * @usb_device: pointer to the usb device
+ * @reg_addr: register address for arbitrary DCI access
+ */
+struct most_dci_obj {
+       struct device dev;
+       struct usb_device *usb_device;
+       u16 reg_addr;
+};
+
+#define to_dci_obj(p) container_of(p, struct most_dci_obj, dev)
+
+struct most_dev;
+
+struct clear_hold_work {
+       struct work_struct ws;
+       struct most_dev *mdev;
+       unsigned int channel;
+       int pipe;
+};
+
+#define to_clear_hold_work(w) container_of(w, struct clear_hold_work, ws)
+
+/**
+ * struct most_dev - holds all usb interface specific stuff
+ * @usb_device: pointer to usb device
+ * @iface: hardware interface
+ * @cap: channel capabilities
+ * @conf: channel configuration
+ * @dci: direct communication interface of hardware
+ * @ep_address: endpoint address table
+ * @description: device description
+ * @suffix: suffix for channel name
+ * @channel_lock: synchronize channel access
+ * @padding_active: indicates channel uses padding
+ * @is_channel_healthy: health status table of each channel
+ * @busy_urbs: list of anchored items
+ * @io_mutex: synchronize I/O with disconnect
+ * @link_stat_timer: timer for link status reports
+ * @poll_work_obj: work for polling link status
+ */
+struct most_dev {
+       struct device dev;
+       struct usb_device *usb_device;
+       struct most_interface iface;
+       struct most_channel_capability *cap;
+       struct most_channel_config *conf;
+       struct most_dci_obj *dci;
+       u8 *ep_address;
+       char description[MAX_STRING_LEN];
+       char suffix[MAX_NUM_ENDPOINTS][MAX_SUFFIX_LEN];
+       spinlock_t channel_lock[MAX_NUM_ENDPOINTS]; /* sync channel access */
+       bool padding_active[MAX_NUM_ENDPOINTS];
+       bool is_channel_healthy[MAX_NUM_ENDPOINTS];
+       struct clear_hold_work clear_work[MAX_NUM_ENDPOINTS];
+       struct usb_anchor *busy_urbs;
+       struct mutex io_mutex;
+       struct timer_list link_stat_timer;
+       struct work_struct poll_work_obj;
+       void (*on_netinfo)(struct most_interface *most_iface,
+                          unsigned char link_state, unsigned char *addrs);
+};
+
+#define to_mdev(d) container_of(d, struct most_dev, iface)
+#define to_mdev_from_dev(d) container_of(d, struct most_dev, dev)
+#define to_mdev_from_work(w) container_of(w, struct most_dev, poll_work_obj)
+
+static void wq_clear_halt(struct work_struct *wq_obj);
+static void wq_netinfo(struct work_struct *wq_obj);
+
+/**
+ * drci_rd_reg - read a DCI register
+ * @dev: usb device
+ * @reg: register address
+ * @buf: buffer to store data
+ *
+ * This is reads data from INIC's direct register communication interface
+ */
+static inline int drci_rd_reg(struct usb_device *dev, u16 reg, u16 *buf)
+{
+       int retval;
+       __le16 *dma_buf;
+       u8 req_type = USB_DIR_IN | USB_TYPE_VENDOR | USB_RECIP_DEVICE;
+
+       dma_buf = kzalloc(sizeof(*dma_buf), GFP_KERNEL);
+       if (!dma_buf)
+               return -ENOMEM;
+
+       retval = usb_control_msg(dev, usb_rcvctrlpipe(dev, 0),
+                                DRCI_READ_REQ, req_type,
+                                0x0000,
+                                reg, dma_buf, sizeof(*dma_buf), 5 * HZ);
+       *buf = le16_to_cpu(*dma_buf);
+       kfree(dma_buf);
+
+       if (retval < 0)
+               return retval;
+       return 0;
+}
+
+/**
+ * drci_wr_reg - write a DCI register
+ * @dev: usb device
+ * @reg: register address
+ * @data: data to write
+ *
+ * This is writes data to INIC's direct register communication interface
+ */
+static inline int drci_wr_reg(struct usb_device *dev, u16 reg, u16 data)
+{
+       return usb_control_msg(dev,
+                              usb_sndctrlpipe(dev, 0),
+                              DRCI_WRITE_REQ,
+                              USB_DIR_OUT | USB_TYPE_VENDOR | USB_RECIP_DEVICE,
+                              data,
+                              reg,
+                              NULL,
+                              0,
+                              5 * HZ);
+}
+
+static inline int start_sync_ep(struct usb_device *usb_dev, u16 ep)
+{
+       return drci_wr_reg(usb_dev, DRCI_REG_BASE + DRCI_COMMAND + ep * 16, 1);
+}
+
+/**
+ * get_stream_frame_size - calculate frame size of current configuration
+ * @dev: device structure
+ * @cfg: channel configuration
+ */
+static unsigned int get_stream_frame_size(struct device *dev,
+                                         struct most_channel_config *cfg)
+{
+       unsigned int frame_size;
+       unsigned int sub_size = cfg->subbuffer_size;
+
+       if (!sub_size) {
+               dev_warn(dev, "Misconfig: Subbuffer size zero.\n");
+               return 0;
+       }
+       switch (cfg->data_type) {
+       case MOST_CH_ISOC:
+               frame_size = AV_PACKETS_PER_XACT * sub_size;
+               break;
+       case MOST_CH_SYNC:
+               if (cfg->packets_per_xact == 0) {
+                       dev_warn(dev, "Misconfig: Packets per XACT zero\n");
+                       frame_size = 0;
+               } else if (cfg->packets_per_xact == 0xFF) {
+                       frame_size = (USB_MTU / sub_size) * sub_size;
+               } else {
+                       frame_size = cfg->packets_per_xact * sub_size;
+               }
+               break;
+       default:
+               dev_warn(dev, "Query frame size of non-streaming channel\n");
+               frame_size = 0;
+               break;
+       }
+       return frame_size;
+}
+
+/**
+ * hdm_poison_channel - mark buffers of this channel as invalid
+ * @iface: pointer to the interface
+ * @channel: channel ID
+ *
+ * This unlinks all URBs submitted to the HCD,
+ * calls the associated completion function of the core and removes
+ * them from the list.
+ *
+ * Returns 0 on success or error code otherwise.
+ */
+static int hdm_poison_channel(struct most_interface *iface, int channel)
+{
+       struct most_dev *mdev = to_mdev(iface);
+       unsigned long flags;
+       spinlock_t *lock; /* temp. lock */
+
+       if (channel < 0 || channel >= iface->num_channels) {
+               dev_warn(&mdev->usb_device->dev, "Channel ID out of range.\n");
+               return -ECHRNG;
+       }
+
+       lock = mdev->channel_lock + channel;
+       spin_lock_irqsave(lock, flags);
+       mdev->is_channel_healthy[channel] = false;
+       spin_unlock_irqrestore(lock, flags);
+
+       cancel_work_sync(&mdev->clear_work[channel].ws);
+
+       mutex_lock(&mdev->io_mutex);
+       usb_kill_anchored_urbs(&mdev->busy_urbs[channel]);
+       if (mdev->padding_active[channel])
+               mdev->padding_active[channel] = false;
+
+       if (mdev->conf[channel].data_type == MOST_CH_ASYNC) {
+               del_timer_sync(&mdev->link_stat_timer);
+               cancel_work_sync(&mdev->poll_work_obj);
+       }
+       mutex_unlock(&mdev->io_mutex);
+       return 0;
+}
+
+/**
+ * hdm_add_padding - add padding bytes
+ * @mdev: most device
+ * @channel: channel ID
+ * @mbo: buffer object
+ *
+ * This inserts the INIC hardware specific padding bytes into a streaming
+ * channel's buffer
+ */
+static int hdm_add_padding(struct most_dev *mdev, int channel, struct mbo *mbo)
+{
+       struct most_channel_config *conf = &mdev->conf[channel];
+       unsigned int frame_size = get_stream_frame_size(&mdev->dev, conf);
+       unsigned int j, num_frames;
+
+       if (!frame_size)
+               return -EINVAL;
+       num_frames = mbo->buffer_length / frame_size;
+
+       if (num_frames < 1) {
+               dev_err(&mdev->usb_device->dev,
+                       "Missed minimal transfer unit.\n");
+               return -EINVAL;
+       }
+
+       for (j = num_frames - 1; j > 0; j--)
+               memmove(mbo->virt_address + j * USB_MTU,
+                       mbo->virt_address + j * frame_size,
+                       frame_size);
+       mbo->buffer_length = num_frames * USB_MTU;
+       return 0;
+}
+
+/**
+ * hdm_remove_padding - remove padding bytes
+ * @mdev: most device
+ * @channel: channel ID
+ * @mbo: buffer object
+ *
+ * This takes the INIC hardware specific padding bytes off a streaming
+ * channel's buffer.
+ */
+static int hdm_remove_padding(struct most_dev *mdev, int channel,
+                             struct mbo *mbo)
+{
+       struct most_channel_config *const conf = &mdev->conf[channel];
+       unsigned int frame_size = get_stream_frame_size(&mdev->dev, conf);
+       unsigned int j, num_frames;
+
+       if (!frame_size)
+               return -EINVAL;
+       num_frames = mbo->processed_length / USB_MTU;
+
+       for (j = 1; j < num_frames; j++)
+               memmove(mbo->virt_address + frame_size * j,
+                       mbo->virt_address + USB_MTU * j,
+                       frame_size);
+
+       mbo->processed_length = frame_size * num_frames;
+       return 0;
+}
+
+/**
+ * hdm_write_completion - completion function for submitted Tx URBs
+ * @urb: the URB that has been completed
+ *
+ * This checks the status of the completed URB. In case the URB has been
+ * unlinked before, it is immediately freed. On any other error the MBO
+ * transfer flag is set. On success it frees allocated resources and calls
+ * the completion function.
+ *
+ * Context: interrupt!
+ */
+static void hdm_write_completion(struct urb *urb)
+{
+       struct mbo *mbo = urb->context;
+       struct most_dev *mdev = to_mdev(mbo->ifp);
+       unsigned int channel = mbo->hdm_channel_id;
+       spinlock_t *lock = mdev->channel_lock + channel;
+       unsigned long flags;
+
+       spin_lock_irqsave(lock, flags);
+
+       mbo->processed_length = 0;
+       mbo->status = MBO_E_INVAL;
+       if (likely(mdev->is_channel_healthy[channel])) {
+               switch (urb->status) {
+               case 0:
+               case -ESHUTDOWN:
+                       mbo->processed_length = urb->actual_length;
+                       mbo->status = MBO_SUCCESS;
+                       break;
+               case -EPIPE:
+                       dev_warn(&mdev->usb_device->dev,
+                                "Broken pipe on ep%02x\n",
+                                mdev->ep_address[channel]);
+                       mdev->is_channel_healthy[channel] = false;
+                       mdev->clear_work[channel].pipe = urb->pipe;
+                       schedule_work(&mdev->clear_work[channel].ws);
+                       break;
+               case -ENODEV:
+               case -EPROTO:
+                       mbo->status = MBO_E_CLOSE;
+                       break;
+               }
+       }
+
+       spin_unlock_irqrestore(lock, flags);
+
+       if (likely(mbo->complete))
+               mbo->complete(mbo);
+       usb_free_urb(urb);
+}
+
+/**
+ * hdm_read_completion - completion function for submitted Rx URBs
+ * @urb: the URB that has been completed
+ *
+ * This checks the status of the completed URB. In case the URB has been
+ * unlinked before it is immediately freed. On any other error the MBO transfer
+ * flag is set. On success it frees allocated resources, removes
+ * padding bytes -if necessary- and calls the completion function.
+ *
+ * Context: interrupt!
+ */
+static void hdm_read_completion(struct urb *urb)
+{
+       struct mbo *mbo = urb->context;
+       struct most_dev *mdev = to_mdev(mbo->ifp);
+       unsigned int channel = mbo->hdm_channel_id;
+       struct device *dev = &mdev->usb_device->dev;
+       spinlock_t *lock = mdev->channel_lock + channel;
+       unsigned long flags;
+
+       spin_lock_irqsave(lock, flags);
+
+       mbo->processed_length = 0;
+       mbo->status = MBO_E_INVAL;
+       if (likely(mdev->is_channel_healthy[channel])) {
+               switch (urb->status) {
+               case 0:
+               case -ESHUTDOWN:
+                       mbo->processed_length = urb->actual_length;
+                       mbo->status = MBO_SUCCESS;
+                       if (mdev->padding_active[channel] &&
+                           hdm_remove_padding(mdev, channel, mbo)) {
+                               mbo->processed_length = 0;
+                               mbo->status = MBO_E_INVAL;
+                       }
+                       break;
+               case -EPIPE:
+                       dev_warn(dev, "Broken pipe on ep%02x\n",
+                                mdev->ep_address[channel]);
+                       mdev->is_channel_healthy[channel] = false;
+                       mdev->clear_work[channel].pipe = urb->pipe;
+                       schedule_work(&mdev->clear_work[channel].ws);
+                       break;
+               case -ENODEV:
+               case -EPROTO:
+                       mbo->status = MBO_E_CLOSE;
+                       break;
+               case -EOVERFLOW:
+                       dev_warn(dev, "Babble on ep%02x\n",
+                                mdev->ep_address[channel]);
+                       break;
+               }
+       }
+
+       spin_unlock_irqrestore(lock, flags);
+
+       if (likely(mbo->complete))
+               mbo->complete(mbo);
+       usb_free_urb(urb);
+}
+
+/**
+ * hdm_enqueue - receive a buffer to be used for data transfer
+ * @iface: interface to enqueue to
+ * @channel: ID of the channel
+ * @mbo: pointer to the buffer object
+ *
+ * This allocates a new URB and fills it according to the channel
+ * that is being used for transmission of data. Before the URB is
+ * submitted it is stored in the private anchor list.
+ *
+ * Returns 0 on success. On any error the URB is freed and a error code
+ * is returned.
+ *
+ * Context: Could in _some_ cases be interrupt!
+ */
+static int hdm_enqueue(struct most_interface *iface, int channel,
+                      struct mbo *mbo)
+{
+       struct most_dev *mdev = to_mdev(iface);
+       struct most_channel_config *conf;
+       int retval = 0;
+       struct urb *urb;
+       unsigned long length;
+       void *virt_address;
+
+       if (!mbo)
+               return -EINVAL;
+       if (iface->num_channels <= channel || channel < 0)
+               return -ECHRNG;
+
+       urb = usb_alloc_urb(NO_ISOCHRONOUS_URB, GFP_KERNEL);
+       if (!urb)
+               return -ENOMEM;
+
+       conf = &mdev->conf[channel];
+
+       mutex_lock(&mdev->io_mutex);
+       if (!mdev->usb_device) {
+               retval = -ENODEV;
+               goto err_free_urb;
+       }
+
+       if ((conf->direction & MOST_CH_TX) && mdev->padding_active[channel] &&
+           hdm_add_padding(mdev, channel, mbo)) {
+               retval = -EINVAL;
+               goto err_free_urb;
+       }
+
+       urb->transfer_dma = mbo->bus_address;
+       virt_address = mbo->virt_address;
+       length = mbo->buffer_length;
+
+       if (conf->direction & MOST_CH_TX) {
+               usb_fill_bulk_urb(urb, mdev->usb_device,
+                                 usb_sndbulkpipe(mdev->usb_device,
+                                                 mdev->ep_address[channel]),
+                                 virt_address,
+                                 length,
+                                 hdm_write_completion,
+                                 mbo);
+               if (conf->data_type != MOST_CH_ISOC &&
+                   conf->data_type != MOST_CH_SYNC)
+                       urb->transfer_flags |= URB_ZERO_PACKET;
+       } else {
+               usb_fill_bulk_urb(urb, mdev->usb_device,
+                                 usb_rcvbulkpipe(mdev->usb_device,
+                                                 mdev->ep_address[channel]),
+                                 virt_address,
+                                 length + conf->extra_len,
+                                 hdm_read_completion,
+                                 mbo);
+       }
+       urb->transfer_flags |= URB_NO_TRANSFER_DMA_MAP;
+
+       usb_anchor_urb(urb, &mdev->busy_urbs[channel]);
+
+       retval = usb_submit_urb(urb, GFP_KERNEL);
+       if (retval) {
+               dev_err(&mdev->usb_device->dev,
+                       "URB submit failed with error %d.\n", retval);
+               goto err_unanchor_urb;
+       }
+       mutex_unlock(&mdev->io_mutex);
+       return 0;
+
+err_unanchor_urb:
+       usb_unanchor_urb(urb);
+err_free_urb:
+       usb_free_urb(urb);
+       mutex_unlock(&mdev->io_mutex);
+       return retval;
+}
+
+static void *hdm_dma_alloc(struct mbo *mbo, u32 size)
+{
+       struct most_dev *mdev = to_mdev(mbo->ifp);
+
+       return usb_alloc_coherent(mdev->usb_device, size, GFP_KERNEL,
+                                 &mbo->bus_address);
+}
+
+static void hdm_dma_free(struct mbo *mbo, u32 size)
+{
+       struct most_dev *mdev = to_mdev(mbo->ifp);
+
+       usb_free_coherent(mdev->usb_device, size, mbo->virt_address,
+                         mbo->bus_address);
+}
+
+/**
+ * hdm_configure_channel - receive channel configuration from core
+ * @iface: interface
+ * @channel: channel ID
+ * @conf: structure that holds the configuration information
+ *
+ * The attached network interface controller (NIC) supports a padding mode
+ * to avoid short packets on USB, hence increasing the performance due to a
+ * lower interrupt load. This mode is default for synchronous data and can
+ * be switched on for isochronous data. In case padding is active the
+ * driver needs to know the frame size of the payload in order to calculate
+ * the number of bytes it needs to pad when transmitting or to cut off when
+ * receiving data.
+ *
+ */
+static int hdm_configure_channel(struct most_interface *iface, int channel,
+                                struct most_channel_config *conf)
+{
+       unsigned int num_frames;
+       unsigned int frame_size;
+       struct most_dev *mdev = to_mdev(iface);
+       struct device *dev = &mdev->usb_device->dev;
+
+       if (!conf) {
+               dev_err(dev, "Bad config pointer.\n");
+               return -EINVAL;
+       }
+       if (channel < 0 || channel >= iface->num_channels) {
+               dev_err(dev, "Channel ID out of range.\n");
+               return -EINVAL;
+       }
+
+       mdev->is_channel_healthy[channel] = true;
+       mdev->clear_work[channel].channel = channel;
+       mdev->clear_work[channel].mdev = mdev;
+       INIT_WORK(&mdev->clear_work[channel].ws, wq_clear_halt);
+
+       if (!conf->num_buffers || !conf->buffer_size) {
+               dev_err(dev, "Misconfig: buffer size or #buffers zero.\n");
+               return -EINVAL;
+       }
+
+       if (conf->data_type != MOST_CH_SYNC &&
+           !(conf->data_type == MOST_CH_ISOC &&
+             conf->packets_per_xact != 0xFF)) {
+               mdev->padding_active[channel] = false;
+               /*
+                * Since the NIC's padding mode is not going to be
+                * used, we can skip the frame size calculations and
+                * move directly on to exit.
+                */
+               goto exit;
+       }
+
+       mdev->padding_active[channel] = true;
+
+       frame_size = get_stream_frame_size(&mdev->dev, conf);
+       if (frame_size == 0 || frame_size > USB_MTU) {
+               dev_warn(dev, "Misconfig: frame size wrong\n");
+               return -EINVAL;
+       }
+
+       num_frames = conf->buffer_size / frame_size;
+
+       if (conf->buffer_size % frame_size) {
+               u16 old_size = conf->buffer_size;
+
+               conf->buffer_size = num_frames * frame_size;
+               dev_warn(dev, "%s: fixed buffer size (%d -> %d)\n",
+                        mdev->suffix[channel], old_size, conf->buffer_size);
+       }
+
+       /* calculate extra length to comply w/ HW padding */
+       conf->extra_len = num_frames * (USB_MTU - frame_size);
+
+exit:
+       mdev->conf[channel] = *conf;
+       if (conf->data_type == MOST_CH_ASYNC) {
+               u16 ep = mdev->ep_address[channel];
+
+               if (start_sync_ep(mdev->usb_device, ep) < 0)
+                       dev_warn(dev, "sync for ep%02x failed", ep);
+       }
+       return 0;
+}
+
+/**
+ * hdm_request_netinfo - request network information
+ * @iface: pointer to interface
+ * @channel: channel ID
+ *
+ * This is used as trigger to set up the link status timer that
+ * polls for the NI state of the INIC every 2 seconds.
+ *
+ */
+static void hdm_request_netinfo(struct most_interface *iface, int channel,
+                               void (*on_netinfo)(struct most_interface *,
+                                                  unsigned char,
+                                                  unsigned char *))
+{
+       struct most_dev *mdev = to_mdev(iface);
+
+       mdev->on_netinfo = on_netinfo;
+       if (!on_netinfo)
+               return;
+
+       mdev->link_stat_timer.expires = jiffies + HZ;
+       mod_timer(&mdev->link_stat_timer, mdev->link_stat_timer.expires);
+}
+
+/**
+ * link_stat_timer_handler - schedule work obtaining mac address and link 
status
+ * @data: pointer to USB device instance
+ *
+ * The handler runs in interrupt context. That's why we need to defer the
+ * tasks to a work queue.
+ */
+static void link_stat_timer_handler(struct timer_list *t)
+{
+       struct most_dev *mdev = from_timer(mdev, t, link_stat_timer);
+
+       schedule_work(&mdev->poll_work_obj);
+       mdev->link_stat_timer.expires = jiffies + (2 * HZ);
+       add_timer(&mdev->link_stat_timer);
+}
+
+/**
+ * wq_netinfo - work queue function to deliver latest networking information
+ * @wq_obj: object that holds data for our deferred work to do
+ *
+ * This retrieves the network interface status of the USB INIC
+ */
+static void wq_netinfo(struct work_struct *wq_obj)
+{
+       struct most_dev *mdev = to_mdev_from_work(wq_obj);
+       struct usb_device *usb_device = mdev->usb_device;
+       struct device *dev = &usb_device->dev;
+       u16 hi, mi, lo, link;
+       u8 hw_addr[6];
+
+       if (drci_rd_reg(usb_device, DRCI_REG_HW_ADDR_HI, &hi)) {
+               dev_err(dev, "Vendor request 'hw_addr_hi' failed\n");
+               return;
+       }
+
+       if (drci_rd_reg(usb_device, DRCI_REG_HW_ADDR_MI, &mi)) {
+               dev_err(dev, "Vendor request 'hw_addr_mid' failed\n");
+               return;
+       }
+
+       if (drci_rd_reg(usb_device, DRCI_REG_HW_ADDR_LO, &lo)) {
+               dev_err(dev, "Vendor request 'hw_addr_low' failed\n");
+               return;
+       }
+
+       if (drci_rd_reg(usb_device, DRCI_REG_NI_STATE, &link)) {
+               dev_err(dev, "Vendor request 'link status' failed\n");
+               return;
+       }
+
+       hw_addr[0] = hi >> 8;
+       hw_addr[1] = hi;
+       hw_addr[2] = mi >> 8;
+       hw_addr[3] = mi;
+       hw_addr[4] = lo >> 8;
+       hw_addr[5] = lo;
+
+       if (mdev->on_netinfo)
+               mdev->on_netinfo(&mdev->iface, link, hw_addr);
+}
+
+/**
+ * wq_clear_halt - work queue function
+ * @wq_obj: work_struct object to execute
+ *
+ * This sends a clear_halt to the given USB pipe.
+ */
+static void wq_clear_halt(struct work_struct *wq_obj)
+{
+       struct clear_hold_work *clear_work = to_clear_hold_work(wq_obj);
+       struct most_dev *mdev = clear_work->mdev;
+       unsigned int channel = clear_work->channel;
+       int pipe = clear_work->pipe;
+       int snd_pipe;
+       int peer;
+
+       mutex_lock(&mdev->io_mutex);
+       most_stop_enqueue(&mdev->iface, channel);
+       usb_kill_anchored_urbs(&mdev->busy_urbs[channel]);
+       if (usb_clear_halt(mdev->usb_device, pipe))
+               dev_warn(&mdev->usb_device->dev, "Failed to reset endpoint.\n");
+
+       /* If the functional Stall condition has been set on an
+        * asynchronous rx channel, we need to clear the tx channel
+        * too, since the hardware runs its clean-up sequence on both
+        * channels, as they are physically one on the network.
+        *
+        * The USB interface that exposes the asynchronous channels
+        * contains always two endpoints, and two only.
+        */
+       if (mdev->conf[channel].data_type == MOST_CH_ASYNC &&
+           mdev->conf[channel].direction == MOST_CH_RX) {
+               if (channel == 0)
+                       peer = 1;
+               else
+                       peer = 0;
+               snd_pipe = usb_sndbulkpipe(mdev->usb_device,
+                                          mdev->ep_address[peer]);
+               usb_clear_halt(mdev->usb_device, snd_pipe);
+       }
+       mdev->is_channel_healthy[channel] = true;
+       most_resume_enqueue(&mdev->iface, channel);
+       mutex_unlock(&mdev->io_mutex);
+}
+
+/**
+ * hdm_usb_fops - file operation table for USB driver
+ */
+static const struct file_operations hdm_usb_fops = {
+       .owner = THIS_MODULE,
+};
+
+/**
+ * usb_device_id - ID table for HCD device probing
+ */
+static const struct usb_device_id usbid[] = {
+       { USB_DEVICE(USB_VENDOR_ID_SMSC, USB_DEV_ID_BRDG), },
+       { USB_DEVICE(USB_VENDOR_ID_SMSC, USB_DEV_ID_OS81118), },
+       { USB_DEVICE(USB_VENDOR_ID_SMSC, USB_DEV_ID_OS81119), },
+       { USB_DEVICE(USB_VENDOR_ID_SMSC, USB_DEV_ID_OS81210), },
+       { } /* Terminating entry */
+};
+
+struct regs {
+       const char *name;
+       u16 reg;
+};
+
+static const struct regs ro_regs[] = {
+       { "ni_state", DRCI_REG_NI_STATE },
+       { "packet_bandwidth", DRCI_REG_PACKET_BW },
+       { "node_address", DRCI_REG_NODE_ADDR },
+       { "node_position", DRCI_REG_NODE_POS },
+};
+
+static const struct regs rw_regs[] = {
+       { "mep_filter", DRCI_REG_MEP_FILTER },
+       { "mep_hash0", DRCI_REG_HASH_TBL0 },
+       { "mep_hash1", DRCI_REG_HASH_TBL1 },
+       { "mep_hash2", DRCI_REG_HASH_TBL2 },
+       { "mep_hash3", DRCI_REG_HASH_TBL3 },
+       { "mep_eui48_hi", DRCI_REG_HW_ADDR_HI },
+       { "mep_eui48_mi", DRCI_REG_HW_ADDR_MI },
+       { "mep_eui48_lo", DRCI_REG_HW_ADDR_LO },
+};
+
+static int get_stat_reg_addr(const struct regs *regs, int size,
+                            const char *name, u16 *reg_addr)
+{
+       int i;
+
+       for (i = 0; i < size; i++) {
+               if (sysfs_streq(name, regs[i].name)) {
+                       *reg_addr = regs[i].reg;
+                       return 0;
+               }
+       }
+       return -EINVAL;
+}
+
+#define get_static_reg_addr(regs, name, reg_addr) \
+       get_stat_reg_addr(regs, ARRAY_SIZE(regs), name, reg_addr)
+
+static ssize_t value_show(struct device *dev, struct device_attribute *attr,
+                         char *buf)
+{
+       const char *name = attr->attr.name;
+       struct most_dci_obj *dci_obj = to_dci_obj(dev);
+       u16 val;
+       u16 reg_addr;
+       int err;
+
+       if (sysfs_streq(name, "arb_address"))
+               return snprintf(buf, PAGE_SIZE, "%04x\n", dci_obj->reg_addr);
+
+       if (sysfs_streq(name, "arb_value"))
+               reg_addr = dci_obj->reg_addr;
+       else if (get_static_reg_addr(ro_regs, name, &reg_addr) &&
+                get_static_reg_addr(rw_regs, name, &reg_addr))
+               return -EINVAL;
+
+       err = drci_rd_reg(dci_obj->usb_device, reg_addr, &val);
+       if (err < 0)
+               return err;
+
+       return snprintf(buf, PAGE_SIZE, "%04x\n", val);
+}
+
+static ssize_t value_store(struct device *dev, struct device_attribute *attr,
+                          const char *buf, size_t count)
+{
+       u16 val;
+       u16 reg_addr;
+       const char *name = attr->attr.name;
+       struct most_dci_obj *dci_obj = to_dci_obj(dev);
+       struct usb_device *usb_dev = dci_obj->usb_device;
+       int err;
+
+       err = kstrtou16(buf, 16, &val);
+       if (err)
+               return err;
+
+       if (sysfs_streq(name, "arb_address")) {
+               dci_obj->reg_addr = val;
+               return count;
+       }
+
+       if (sysfs_streq(name, "arb_value"))
+               err = drci_wr_reg(usb_dev, dci_obj->reg_addr, val);
+       else if (sysfs_streq(name, "sync_ep"))
+               err = start_sync_ep(usb_dev, val);
+       else if (!get_static_reg_addr(rw_regs, name, &reg_addr))
+               err = drci_wr_reg(usb_dev, reg_addr, val);
+       else
+               return -EINVAL;
+
+       if (err < 0)
+               return err;
+
+       return count;
+}
+
+static DEVICE_ATTR(ni_state, 0444, value_show, NULL);
+static DEVICE_ATTR(packet_bandwidth, 0444, value_show, NULL);
+static DEVICE_ATTR(node_address, 0444, value_show, NULL);
+static DEVICE_ATTR(node_position, 0444, value_show, NULL);
+static DEVICE_ATTR(sync_ep, 0200, NULL, value_store);
+static DEVICE_ATTR(mep_filter, 0644, value_show, value_store);
+static DEVICE_ATTR(mep_hash0, 0644, value_show, value_store);
+static DEVICE_ATTR(mep_hash1, 0644, value_show, value_store);
+static DEVICE_ATTR(mep_hash2, 0644, value_show, value_store);
+static DEVICE_ATTR(mep_hash3, 0644, value_show, value_store);
+static DEVICE_ATTR(mep_eui48_hi, 0644, value_show, value_store);
+static DEVICE_ATTR(mep_eui48_mi, 0644, value_show, value_store);
+static DEVICE_ATTR(mep_eui48_lo, 0644, value_show, value_store);
+static DEVICE_ATTR(arb_address, 0644, value_show, value_store);
+static DEVICE_ATTR(arb_value, 0644, value_show, value_store);
+
+static struct attribute *dci_attrs[] = {
+       &dev_attr_ni_state.attr,
+       &dev_attr_packet_bandwidth.attr,
+       &dev_attr_node_address.attr,
+       &dev_attr_node_position.attr,
+       &dev_attr_sync_ep.attr,
+       &dev_attr_mep_filter.attr,
+       &dev_attr_mep_hash0.attr,
+       &dev_attr_mep_hash1.attr,
+       &dev_attr_mep_hash2.attr,
+       &dev_attr_mep_hash3.attr,
+       &dev_attr_mep_eui48_hi.attr,
+       &dev_attr_mep_eui48_mi.attr,
+       &dev_attr_mep_eui48_lo.attr,
+       &dev_attr_arb_address.attr,
+       &dev_attr_arb_value.attr,
+       NULL,
+};
+
+ATTRIBUTE_GROUPS(dci);
+
+static void release_dci(struct device *dev)
+{
+       struct most_dci_obj *dci = to_dci_obj(dev);
+
+       put_device(dev->parent);
+       kfree(dci);
+}
+
+static void release_mdev(struct device *dev)
+{
+       struct most_dev *mdev = to_mdev_from_dev(dev);
+
+       kfree(mdev);
+}
+/**
+ * hdm_probe - probe function of USB device driver
+ * @interface: Interface of the attached USB device
+ * @id: Pointer to the USB ID table.
+ *
+ * This allocates and initializes the device instance, adds the new
+ * entry to the internal list, scans the USB descriptors and registers
+ * the interface with the core.
+ * Additionally, the DCI objects are created and the hardware is sync'd.
+ *
+ * Return 0 on success. In case of an error a negative number is returned.
+ */
+static int
+hdm_probe(struct usb_interface *interface, const struct usb_device_id *id)
+{
+       struct usb_host_interface *usb_iface_desc = interface->cur_altsetting;
+       struct usb_device *usb_dev = interface_to_usbdev(interface);
+       struct device *dev = &usb_dev->dev;
+       struct most_dev *mdev;
+       unsigned int i;
+       unsigned int num_endpoints;
+       struct most_channel_capability *tmp_cap;
+       struct usb_endpoint_descriptor *ep_desc;
+       int ret = -ENOMEM;
+
+       mdev = kzalloc(sizeof(*mdev), GFP_KERNEL);
+       if (!mdev)
+               return -ENOMEM;
+
+       usb_set_intfdata(interface, mdev);
+       num_endpoints = usb_iface_desc->desc.bNumEndpoints;
+       if (num_endpoints > MAX_NUM_ENDPOINTS) {
+               kfree(mdev);
+               return -EINVAL;
+       }
+       mutex_init(&mdev->io_mutex);
+       INIT_WORK(&mdev->poll_work_obj, wq_netinfo);
+       timer_setup(&mdev->link_stat_timer, link_stat_timer_handler, 0);
+
+       mdev->usb_device = usb_dev;
+       mdev->link_stat_timer.expires = jiffies + (2 * HZ);
+
+       mdev->iface.mod = hdm_usb_fops.owner;
+       mdev->iface.dev = &mdev->dev;
+       mdev->iface.driver_dev = &interface->dev;
+       mdev->iface.interface = ITYPE_USB;
+       mdev->iface.configure = hdm_configure_channel;
+       mdev->iface.request_netinfo = hdm_request_netinfo;
+       mdev->iface.enqueue = hdm_enqueue;
+       mdev->iface.poison_channel = hdm_poison_channel;
+       mdev->iface.dma_alloc = hdm_dma_alloc;
+       mdev->iface.dma_free = hdm_dma_free;
+       mdev->iface.description = mdev->description;
+       mdev->iface.num_channels = num_endpoints;
+
+       snprintf(mdev->description, sizeof(mdev->description),
+                "%d-%s:%d.%d",
+                usb_dev->bus->busnum,
+                usb_dev->devpath,
+                usb_dev->config->desc.bConfigurationValue,
+                usb_iface_desc->desc.bInterfaceNumber);
+
+       mdev->dev.init_name = mdev->description;
+       mdev->dev.parent = &interface->dev;
+       mdev->dev.release = release_mdev;
+       mdev->conf = kcalloc(num_endpoints, sizeof(*mdev->conf), GFP_KERNEL);
+       if (!mdev->conf)
+               goto err_free_mdev;
+
+       mdev->cap = kcalloc(num_endpoints, sizeof(*mdev->cap), GFP_KERNEL);
+       if (!mdev->cap)
+               goto err_free_conf;
+
+       mdev->iface.channel_vector = mdev->cap;
+       mdev->ep_address =
+               kcalloc(num_endpoints, sizeof(*mdev->ep_address), GFP_KERNEL);
+       if (!mdev->ep_address)
+               goto err_free_cap;
+
+       mdev->busy_urbs =
+               kcalloc(num_endpoints, sizeof(*mdev->busy_urbs), GFP_KERNEL);
+       if (!mdev->busy_urbs)
+               goto err_free_ep_address;
+
+       tmp_cap = mdev->cap;
+       for (i = 0; i < num_endpoints; i++) {
+               ep_desc = &usb_iface_desc->endpoint[i].desc;
+               mdev->ep_address[i] = ep_desc->bEndpointAddress;
+               mdev->padding_active[i] = false;
+               mdev->is_channel_healthy[i] = true;
+
+               snprintf(&mdev->suffix[i][0], MAX_SUFFIX_LEN, "ep%02x",
+                        mdev->ep_address[i]);
+
+               tmp_cap->name_suffix = &mdev->suffix[i][0];
+               tmp_cap->buffer_size_packet = MAX_BUF_SIZE;
+               tmp_cap->buffer_size_streaming = MAX_BUF_SIZE;
+               tmp_cap->num_buffers_packet = BUF_CHAIN_SIZE;
+               tmp_cap->num_buffers_streaming = BUF_CHAIN_SIZE;
+               tmp_cap->data_type = MOST_CH_CONTROL | MOST_CH_ASYNC |
+                                    MOST_CH_ISOC | MOST_CH_SYNC;
+               if (usb_endpoint_dir_in(ep_desc))
+                       tmp_cap->direction = MOST_CH_RX;
+               else
+                       tmp_cap->direction = MOST_CH_TX;
+               tmp_cap++;
+               init_usb_anchor(&mdev->busy_urbs[i]);
+               spin_lock_init(&mdev->channel_lock[i]);
+       }
+       dev_dbg(dev, "claimed gadget: Vendor=%4.4x ProdID=%4.4x Bus=%02x 
Device=%02x\n",
+               le16_to_cpu(usb_dev->descriptor.idVendor),
+               le16_to_cpu(usb_dev->descriptor.idProduct),
+               usb_dev->bus->busnum,
+               usb_dev->devnum);
+
+       dev_dbg(dev, "device path: /sys/bus/usb/devices/%d-%s:%d.%d\n",
+               usb_dev->bus->busnum,
+               usb_dev->devpath,
+               usb_dev->config->desc.bConfigurationValue,
+               usb_iface_desc->desc.bInterfaceNumber);
+
+       ret = most_register_interface(&mdev->iface);
+       if (ret)
+               goto err_free_busy_urbs;
+
+       mutex_lock(&mdev->io_mutex);
+       if (le16_to_cpu(usb_dev->descriptor.idProduct) == USB_DEV_ID_OS81118 ||
+           le16_to_cpu(usb_dev->descriptor.idProduct) == USB_DEV_ID_OS81119 ||
+           le16_to_cpu(usb_dev->descriptor.idProduct) == USB_DEV_ID_OS81210) {
+               mdev->dci = kzalloc(sizeof(*mdev->dci), GFP_KERNEL);
+               if (!mdev->dci) {
+                       mutex_unlock(&mdev->io_mutex);
+                       most_deregister_interface(&mdev->iface);
+                       ret = -ENOMEM;
+                       goto err_free_busy_urbs;
+               }
+
+               mdev->dci->dev.init_name = "dci";
+               mdev->dci->dev.parent = get_device(mdev->iface.dev);
+               mdev->dci->dev.groups = dci_groups;
+               mdev->dci->dev.release = release_dci;
+               if (device_register(&mdev->dci->dev)) {
+                       mutex_unlock(&mdev->io_mutex);
+                       most_deregister_interface(&mdev->iface);
+                       ret = -ENOMEM;
+                       goto err_free_dci;
+               }
+               mdev->dci->usb_device = mdev->usb_device;
+       }
+       mutex_unlock(&mdev->io_mutex);
+       return 0;
+err_free_dci:
+       put_device(&mdev->dci->dev);
+err_free_busy_urbs:
+       kfree(mdev->busy_urbs);
+err_free_ep_address:
+       kfree(mdev->ep_address);
+err_free_cap:
+       kfree(mdev->cap);
+err_free_conf:
+       kfree(mdev->conf);
+err_free_mdev:
+       put_device(&mdev->dev);
+       return ret;
+}
+
+/**
+ * hdm_disconnect - disconnect function of USB device driver
+ * @interface: Interface of the attached USB device
+ *
+ * This deregisters the interface with the core, removes the kernel timer
+ * and frees resources.
+ *
+ * Context: hub kernel thread
+ */
+static void hdm_disconnect(struct usb_interface *interface)
+{
+       struct most_dev *mdev = usb_get_intfdata(interface);
+
+       mutex_lock(&mdev->io_mutex);
+       usb_set_intfdata(interface, NULL);
+       mdev->usb_device = NULL;
+       mutex_unlock(&mdev->io_mutex);
+
+       del_timer_sync(&mdev->link_stat_timer);
+       cancel_work_sync(&mdev->poll_work_obj);
+
+       if (mdev->dci)
+               device_unregister(&mdev->dci->dev);
+       most_deregister_interface(&mdev->iface);
+
+       kfree(mdev->busy_urbs);
+       kfree(mdev->cap);
+       kfree(mdev->conf);
+       kfree(mdev->ep_address);
+       put_device(&mdev->dci->dev);
+       put_device(&mdev->dev);
+}
+
+static int hdm_suspend(struct usb_interface *interface, pm_message_t message)
+{
+       struct most_dev *mdev = usb_get_intfdata(interface);
+       int i;
+
+       mutex_lock(&mdev->io_mutex);
+       for (i = 0; i < mdev->iface.num_channels; i++) {
+               most_stop_enqueue(&mdev->iface, i);
+               usb_kill_anchored_urbs(&mdev->busy_urbs[i]);
+       }
+       mutex_unlock(&mdev->io_mutex);
+       return 0;
+}
+
+static int hdm_resume(struct usb_interface *interface)
+{
+       struct most_dev *mdev = usb_get_intfdata(interface);
+       int i;
+
+       mutex_lock(&mdev->io_mutex);
+       for (i = 0; i < mdev->iface.num_channels; i++)
+               most_resume_enqueue(&mdev->iface, i);
+       mutex_unlock(&mdev->io_mutex);
+       return 0;
+}
+
+static struct usb_driver hdm_usb = {
+       .name = "hdm_usb",
+       .id_table = usbid,
+       .probe = hdm_probe,
+       .disconnect = hdm_disconnect,
+       .resume = hdm_resume,
+       .suspend = hdm_suspend,
+};
+
+module_usb_driver(hdm_usb);
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Christian Gromm <christian.gr...@microchip.com>");
+MODULE_DESCRIPTION("HDM_4_USB");
-- 
2.7.4

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