Quelle  i2c-hid-core.c   Sprache: C

/*
 * HID over I2C protocol implementation
 *
 * Copyright (c) 2012 Benjamin Tissoires <benjamin.tissoires@gmail.com>
 * Copyright (c) 2012 Ecole Nationale de l'Aviation Civile, France
 * Copyright (c) 2012 Red Hat, Inc
 *
 * This code is partly based on "USB HID support for Linux":
 *
 *  Copyright (c) 1999 Andreas Gal
 *  Copyright (c) 2000-2005 Vojtech Pavlik <vojtech@suse.cz>
 *  Copyright (c) 2005 Michael Haboustak <mike-@cinci.rr.com> for Concept2, Inc
 *  Copyright (c) 2007-2008 Oliver Neukum
 *  Copyright (c) 2006-2010 Jiri Kosina
 *
 * This file is subject to the terms and conditions of the GNU General Public
 * License.  See the file COPYING in the main directory of this archive for
 * more details.
 */

#include <linux/module.h>
#include <linux/i2c.h>
#include <linux/interrupt.h>
#include <linux/input.h>
#include <linux/irq.h>
#include <linux/delay.h>
#include <linux/slab.h>
#include <linux/pm.h>
#include <linux/pm_wakeirq.h>
#include <linux/device.h>
#include <linux/wait.h>
#include <linux/err.h>
#include <linux/string.h>
#include <linux/list.h>
#include <linux/jiffies.h>
#include <linux/kernel.h>
#include <linux/hid.h>
#include <linux/mutex.h>
#include <linux/unaligned.h>

#include <drm/drm_panel.h>

#include "../hid-ids.h"
#include "i2c-hid.h"

/* quirks to control the device */
#define I2C_HID_QUIRK_NO_IRQ_AFTER_RESET BIT(0)
#define I2C_HID_QUIRK_BOGUS_IRQ   BIT(1)
#define I2C_HID_QUIRK_RESET_ON_RESUME  BIT(2)
#define I2C_HID_QUIRK_BAD_INPUT_SIZE  BIT(3)
#define I2C_HID_QUIRK_NO_WAKEUP_AFTER_RESET BIT(4)
#define I2C_HID_QUIRK_NO_SLEEP_ON_SUSPEND BIT(5)
#define I2C_HID_QUIRK_DELAY_WAKEUP_AFTER_RESUME BIT(6)
#define I2C_HID_QUIRK_RE_POWER_ON  BIT(7)

/* Command opcodes */
#define I2C_HID_OPCODE_RESET   0x01
#define I2C_HID_OPCODE_GET_REPORT  0x02
#define I2C_HID_OPCODE_SET_REPORT  0x03
#define I2C_HID_OPCODE_GET_IDLE   0x04
#define I2C_HID_OPCODE_SET_IDLE   0x05
#define I2C_HID_OPCODE_GET_PROTOCOL  0x06
#define I2C_HID_OPCODE_SET_PROTOCOL  0x07
#define I2C_HID_OPCODE_SET_POWER  0x08

/* flags */
#define I2C_HID_STARTED  0
#define I2C_HID_RESET_PENDING 1

#define I2C_HID_PWR_ON  0x00
#define I2C_HID_PWR_SLEEP 0x01

#define i2c_hid_dbg(ihid, ...) dev_dbg(&(ihid)->client->dev, __VA_ARGS__)

struct i2c_hid_desc {
 __le16 wHIDDescLength;
 __le16 bcdVersion;
 __le16 wReportDescLength;
 __le16 wReportDescRegister;
 __le16 wInputRegister;
 __le16 wMaxInputLength;
 __le16 wOutputRegister;
 __le16 wMaxOutputLength;
 __le16 wCommandRegister;
 __le16 wDataRegister;
 __le16 wVendorID;
 __le16 wProductID;
 __le16 wVersionID;
 __le32 reserved;
} __packed;

/* The main device structure */
struct i2c_hid {
 struct i2c_client *client; /* i2c client */
 struct hid_device *hid; /* pointer to corresponding HID dev */
 struct i2c_hid_desc hdesc;  /* the HID Descriptor */
 __le16   wHIDDescRegister; /* location of the i2c
   * register of the HID
   * descriptor. */
 unsigned int  bufsize; /* i2c buffer size */
 u8   *inbuf;  /* Input buffer */
 u8   *rawbuf; /* Raw Input buffer */
 u8   *cmdbuf; /* Command buffer */

 unsigned long  flags;  /* device flags */
 unsigned long  quirks;  /* Various quirks */

 wait_queue_head_t wait;  /* For waiting the interrupt */

 struct mutex  cmd_lock; /* protects cmdbuf and rawbuf */
 struct mutex  reset_lock;

 struct i2chid_ops *ops;
 struct drm_panel_follower panel_follower;
 struct work_struct panel_follower_work;
 bool   is_panel_follower;
 bool   panel_follower_work_finished;
};

static const struct i2c_hid_quirks {
 __u16 idVendor;
 __u16 idProduct;
 __u32 quirks;
} i2c_hid_quirks[] = {
 { I2C_VENDOR_ID_HANTICK, I2C_PRODUCT_ID_HANTICK_5288,
  I2C_HID_QUIRK_NO_IRQ_AFTER_RESET },
 { I2C_VENDOR_ID_ITE, I2C_DEVICE_ID_ITE_VOYO_WINPAD_A15,
  I2C_HID_QUIRK_NO_IRQ_AFTER_RESET },
 { I2C_VENDOR_ID_RAYDIUM, I2C_PRODUCT_ID_RAYDIUM_3118,
  I2C_HID_QUIRK_NO_IRQ_AFTER_RESET },
 { USB_VENDOR_ID_ALPS_JP, HID_ANY_ID,
   I2C_HID_QUIRK_RESET_ON_RESUME },
 { I2C_VENDOR_ID_SYNAPTICS, I2C_PRODUCT_ID_SYNAPTICS_SYNA2393,
   I2C_HID_QUIRK_RESET_ON_RESUME },
 { USB_VENDOR_ID_ITE, I2C_DEVICE_ID_ITE_LENOVO_LEGION_Y720,
  I2C_HID_QUIRK_BAD_INPUT_SIZE },
 { I2C_VENDOR_ID_CIRQUE, I2C_PRODUCT_ID_CIRQUE_1063,
  I2C_HID_QUIRK_NO_SLEEP_ON_SUSPEND },
 /*
 * Without additional power on command, at least some QTEC devices send garbage
 */
 { I2C_VENDOR_ID_QTEC, HID_ANY_ID,
  I2C_HID_QUIRK_RE_POWER_ON },
 /*
 * Sending the wakeup after reset actually break ELAN touchscreen controller
 */
 { USB_VENDOR_ID_ELAN, HID_ANY_ID,
   I2C_HID_QUIRK_NO_WAKEUP_AFTER_RESET |
   I2C_HID_QUIRK_BOGUS_IRQ },
 { I2C_VENDOR_ID_GOODIX, I2C_DEVICE_ID_GOODIX_0D42,
   I2C_HID_QUIRK_DELAY_WAKEUP_AFTER_RESUME },
 { 0, 0 }
};

/*
 * i2c_hid_lookup_quirk: return any quirks associated with a I2C HID device
 * @idVendor: the 16-bit vendor ID
 * @idProduct: the 16-bit product ID
 *
 * Returns: a u32 quirks value.
 */
static u32 i2c_hid_lookup_quirk(const u16 idVendor, const u16 idProduct)
{
 u32 quirks = 0;
 int n;

 for (n = 0; i2c_hid_quirks[n].idVendor; n++)
  if (i2c_hid_quirks[n].idVendor == idVendor &&
      (i2c_hid_quirks[n].idProduct == (__u16)HID_ANY_ID ||
       i2c_hid_quirks[n].idProduct == idProduct))
   quirks = i2c_hid_quirks[n].quirks;

 return quirks;
}

static int i2c_hid_probe_address(struct i2c_hid *ihid)
{
 int ret;

 /*
 * Some STM-based devices need 400µs after a rising clock edge to wake
 * from deep sleep, in which case the first read will fail. Try after a
 * short sleep to see if the device came alive on the bus. Certain
 * Weida Tech devices also need this.
 */
 ret = i2c_smbus_read_byte(ihid->client);
 if (ret < 0) {
  usleep_range(400, 500);
  ret = i2c_smbus_read_byte(ihid->client);
 }
 return ret < 0 ? ret : 0;
}

static int i2c_hid_xfer(struct i2c_hid *ihid,
   u8 *send_buf, int send_len, u8 *recv_buf, int recv_len)
{
 struct i2c_client *client = ihid->client;
 struct i2c_msg msgs[2] = { 0 };
 int n = 0;
 int ret;

 if (send_len) {
  i2c_hid_dbg(ihid, "%s: cmd=%*ph\n",
       __func__, send_len, send_buf);

  msgs[n].addr = client->addr;
  msgs[n].flags = (client->flags & I2C_M_TEN) | I2C_M_DMA_SAFE;
  msgs[n].len = send_len;
  msgs[n].buf = send_buf;
  n++;
 }

 if (recv_len) {
  msgs[n].addr = client->addr;
  msgs[n].flags = (client->flags & I2C_M_TEN) |
    I2C_M_RD | I2C_M_DMA_SAFE;
  msgs[n].len = recv_len;
  msgs[n].buf = recv_buf;
  n++;
 }

 ret = i2c_transfer(client->adapter, msgs, n);

 if (ret != n)
  return ret < 0 ? ret : -EIO;

 return 0;
}

static int i2c_hid_read_register(struct i2c_hid *ihid, __le16 reg,
     void *buf, size_t len)
{
 guard(mutex)(&ihid->cmd_lock);

 *(__le16 *)ihid->cmdbuf = reg;

 return i2c_hid_xfer(ihid, ihid->cmdbuf, sizeof(__le16), buf, len);
}

static size_t i2c_hid_encode_command(u8 *buf, u8 opcode,
         int report_type, int report_id)
{
 size_t length = 0;

 if (report_id < 0x0F) {
  buf[length++] = report_type << 4 | report_id;
  buf[length++] = opcode;
 } else {
  buf[length++] = report_type << 4 | 0x0F;
  buf[length++] = opcode;
  buf[length++] = report_id;
 }

 return length;
}

static int i2c_hid_get_report(struct i2c_hid *ihid,
         u8 report_type, u8 report_id,
         u8 *recv_buf, size_t recv_len)
{
 size_t length = 0;
 size_t ret_count;
 int error;

 i2c_hid_dbg(ihid, "%s\n", __func__);

 guard(mutex)(&ihid->cmd_lock);

 /* Command register goes first */
 *(__le16 *)ihid->cmdbuf = ihid->hdesc.wCommandRegister;
 length += sizeof(__le16);
 /* Next is GET_REPORT command */
 length += i2c_hid_encode_command(ihid->cmdbuf + length,
      I2C_HID_OPCODE_GET_REPORT,
      report_type, report_id);
 /*
 * Device will send report data through data register. Because
 * command can be either 2 or 3 bytes destination for the data
 * register may be not aligned.
 */
 put_unaligned_le16(le16_to_cpu(ihid->hdesc.wDataRegister),
      ihid->cmdbuf + length);
 length += sizeof(__le16);

 /*
 * In addition to report data device will supply data length
 * in the first 2 bytes of the response, so adjust .
 */
 error = i2c_hid_xfer(ihid, ihid->cmdbuf, length,
        ihid->rawbuf, recv_len + sizeof(__le16));
 if (error) {
  dev_err(&ihid->client->dev,
   "failed to get a report from device: %d\n", error);
  return error;
 }

 /* The buffer is sufficiently aligned */
 ret_count = le16_to_cpup((__le16 *)ihid->rawbuf);

 /* Check for empty report response */
 if (ret_count <= sizeof(__le16))
  return 0;

 recv_len = min(recv_len, ret_count - sizeof(__le16));
 memcpy(recv_buf, ihid->rawbuf + sizeof(__le16), recv_len);

 if (report_id && recv_len != 0 && recv_buf[0] != report_id) {
  dev_err(&ihid->client->dev,
   "device returned incorrect report (%d vs %d expected)\n",
   recv_buf[0], report_id);
  return -EINVAL;
 }

 return recv_len;
}

static size_t i2c_hid_format_report(u8 *buf, int report_id,
        const u8 *data, size_t size)
{
 size_t length = sizeof(__le16); /* reserve space to store size */

 if (report_id)
  buf[length++] = report_id;

 memcpy(buf + length, data, size);
 length += size;

 /* Store overall size in the beginning of the buffer */
 put_unaligned_le16(length, buf);

 return length;
}

/**
 * i2c_hid_set_or_send_report: forward an incoming report to the device
 * @ihid: the i2c hid device
 * @report_type: 0x03 for HID_FEATURE_REPORT ; 0x02 for HID_OUTPUT_REPORT
 * @report_id: the report ID
 * @buf: the actual data to transfer, without the report ID
 * @data_len: size of buf
 * @do_set: true: use SET_REPORT HID command, false: send plain OUTPUT report
 */
static int i2c_hid_set_or_send_report(struct i2c_hid *ihid,
          u8 report_type, u8 report_id,
          const u8 *buf, size_t data_len,
          bool do_set)
{
 size_t length = 0;
 int error;

 i2c_hid_dbg(ihid, "%s\n", __func__);

 if (data_len > ihid->bufsize)
  return -EINVAL;

 if (!do_set && le16_to_cpu(ihid->hdesc.wMaxOutputLength) == 0)
  return -ENOSYS;

 guard(mutex)(&ihid->cmd_lock);

 if (do_set) {
  /* Command register goes first */
  *(__le16 *)ihid->cmdbuf = ihid->hdesc.wCommandRegister;
  length += sizeof(__le16);
  /* Next is SET_REPORT command */
  length += i2c_hid_encode_command(ihid->cmdbuf + length,
       I2C_HID_OPCODE_SET_REPORT,
       report_type, report_id);
  /*
 * Report data will go into the data register. Because
 * command can be either 2 or 3 bytes destination for
 * the data register may be not aligned.
*/
  put_unaligned_le16(le16_to_cpu(ihid->hdesc.wDataRegister),
       ihid->cmdbuf + length);
  length += sizeof(__le16);
 } else {
  /*
 * With simple "send report" all data goes into the output
 * register.
 */
  *(__le16 *)ihid->cmdbuf = ihid->hdesc.wOutputRegister;
  length += sizeof(__le16);
 }

 length += i2c_hid_format_report(ihid->cmdbuf + length,
     report_id, buf, data_len);

 error = i2c_hid_xfer(ihid, ihid->cmdbuf, length, NULL, 0);
 if (error) {
  dev_err(&ihid->client->dev,
   "failed to set a report to device: %d\n", error);
  return error;
 }

 return data_len;
}

static int i2c_hid_set_power_command(struct i2c_hid *ihid, int power_state)
{
 size_t length;

 guard(mutex)(&ihid->cmd_lock);

 /* SET_POWER uses command register */
 *(__le16 *)ihid->cmdbuf = ihid->hdesc.wCommandRegister;
 length = sizeof(__le16);

 /* Now the command itself */
 length += i2c_hid_encode_command(ihid->cmdbuf + length,
      I2C_HID_OPCODE_SET_POWER,
      0, power_state);

 return i2c_hid_xfer(ihid, ihid->cmdbuf, length, NULL, 0);
}

static int i2c_hid_set_power(struct i2c_hid *ihid, int power_state)
{
 int ret;

 i2c_hid_dbg(ihid, "%s\n", __func__);

 /*
 * Some STM-based devices need 400µs after a rising clock edge to wake
 * from deep sleep, in which case the first request will fail due to
 * the address not being acknowledged. Try after a short sleep to see
 * if the device came alive on the bus. Certain Weida Tech devices also
 * need this.
 */
 ret = i2c_hid_set_power_command(ihid, power_state);
 if (ret && power_state == I2C_HID_PWR_ON) {
  usleep_range(400, 500);
  ret = i2c_hid_set_power_command(ihid, I2C_HID_PWR_ON);
 }

 if (ret)
  dev_err(&ihid->client->dev,
   "failed to change power setting.\n");

 /*
 * The HID over I2C specification states that if a DEVICE needs time
 * after the PWR_ON request, it should utilise CLOCK stretching.
 * However, it has been observered that the Windows driver provides a
 * 1ms sleep between the PWR_ON and RESET requests.
 * According to Goodix Windows even waits 60 ms after (other?)
 * PWR_ON requests. Testing has confirmed that several devices
 * will not work properly without a delay after a PWR_ON request.
 */
 if (!ret && power_state == I2C_HID_PWR_ON)
  msleep(60);

 return ret;
}

static int i2c_hid_start_hwreset(struct i2c_hid *ihid)
{
 size_t length = 0;
 int ret;

 i2c_hid_dbg(ihid, "%s\n", __func__);

 /*
 * This prevents sending feature reports while the device is
 * being reset. Otherwise we may lose the reset complete
 * interrupt.
 */
 lockdep_assert_held(&ihid->reset_lock);

 ret = i2c_hid_set_power(ihid, I2C_HID_PWR_ON);
 if (ret)
  return ret;

 scoped_guard(mutex, &ihid->cmd_lock) {
  /* Prepare reset command. Command register goes first. */
  *(__le16 *)ihid->cmdbuf = ihid->hdesc.wCommandRegister;
  length += sizeof(__le16);
  /* Next is RESET command itself */
  length += i2c_hid_encode_command(ihid->cmdbuf + length,
       I2C_HID_OPCODE_RESET, 0, 0);

  set_bit(I2C_HID_RESET_PENDING, &ihid->flags);

  ret = i2c_hid_xfer(ihid, ihid->cmdbuf, length, NULL, 0);
  if (ret) {
   dev_err(&ihid->client->dev,
    "failed to reset device: %d\n", ret);
   break;
  }

  return 0;
 }

 /* Clean up if sending reset command failed */
 clear_bit(I2C_HID_RESET_PENDING, &ihid->flags);
 i2c_hid_set_power(ihid, I2C_HID_PWR_SLEEP);
 return ret;
}

static int i2c_hid_finish_hwreset(struct i2c_hid *ihid)
{
 int ret = 0;

 i2c_hid_dbg(ihid, "%s: waiting...\n", __func__);

 if (ihid->quirks & I2C_HID_QUIRK_NO_IRQ_AFTER_RESET) {
  msleep(100);
  clear_bit(I2C_HID_RESET_PENDING, &ihid->flags);
 } else if (!wait_event_timeout(ihid->wait,
           !test_bit(I2C_HID_RESET_PENDING, &ihid->flags),
           msecs_to_jiffies(1000))) {
  dev_warn(&ihid->client->dev, "device did not ack reset within 1000 ms\n");
  clear_bit(I2C_HID_RESET_PENDING, &ihid->flags);
 }
 i2c_hid_dbg(ihid, "%s: finished.\n", __func__);

 /* At least some SIS devices need this after reset */
 if (!(ihid->quirks & I2C_HID_QUIRK_NO_WAKEUP_AFTER_RESET))
  ret = i2c_hid_set_power(ihid, I2C_HID_PWR_ON);

 return ret;
}

static void i2c_hid_get_input(struct i2c_hid *ihid)
{
 u16 size = le16_to_cpu(ihid->hdesc.wMaxInputLength);
 u16 ret_size;
 int ret;

 if (size > ihid->bufsize)
  size = ihid->bufsize;

 ret = i2c_master_recv(ihid->client, ihid->inbuf, size);
 if (ret != size) {
  if (ret < 0)
   return;

  dev_err(&ihid->client->dev, "%s: got %d data instead of %d\n",
   __func__, ret, size);
  return;
 }

 /* Receiving buffer is properly aligned */
 ret_size = le16_to_cpup((__le16 *)ihid->inbuf);
 if (!ret_size) {
  /* host or device initiated RESET completed */
  if (test_and_clear_bit(I2C_HID_RESET_PENDING, &ihid->flags))
   wake_up(&ihid->wait);
  return;
 }

 if ((ihid->quirks & I2C_HID_QUIRK_BOGUS_IRQ) && ret_size == 0xffff) {
  dev_warn_once(&ihid->client->dev,
         "%s: IRQ triggered but there's no data\n",
         __func__);
  return;
 }

 if (ret_size > size || ret_size < sizeof(__le16)) {
  if (ihid->quirks & I2C_HID_QUIRK_BAD_INPUT_SIZE) {
   *(__le16 *)ihid->inbuf = cpu_to_le16(size);
   ret_size = size;
  } else {
   dev_err(&ihid->client->dev,
    "%s: incomplete report (%d/%d)\n",
    __func__, size, ret_size);
   return;
  }
 }

 i2c_hid_dbg(ihid, "input: %*ph\n", ret_size, ihid->inbuf);

 if (test_bit(I2C_HID_STARTED, &ihid->flags)) {
  if (ihid->hid->group != HID_GROUP_RMI)
   pm_wakeup_event(&ihid->client->dev, 0);

  hid_input_report(ihid->hid, HID_INPUT_REPORT,
    ihid->inbuf + sizeof(__le16),
    ret_size - sizeof(__le16), 1);
 }

 return;
}

static irqreturn_t i2c_hid_irq(int irq, void *dev_id)
{
 struct i2c_hid *ihid = dev_id;

 i2c_hid_get_input(ihid);

 return IRQ_HANDLED;
}

static int i2c_hid_get_report_length(struct hid_report *report)
{
 return ((report->size - 1) >> 3) + 1 +
  report->device->report_enum[report->type].numbered + 2;
}

/*
 * Traverse the supplied list of reports and find the longest
 */
static void i2c_hid_find_max_report(struct hid_device *hid, unsigned int type,
  unsigned int *max)
{
 struct hid_report *report;
 unsigned int size;

 /* We should not rely on wMaxInputLength, as some devices may set it to
 * a wrong length. */
 list_for_each_entry(report, &hid->report_enum[type].report_list, list) {
  size = i2c_hid_get_report_length(report);
  if (*max < size)
   *max = size;
 }
}

static void i2c_hid_free_buffers(struct i2c_hid *ihid)
{
 kfree(ihid->inbuf);
 kfree(ihid->rawbuf);
 kfree(ihid->cmdbuf);
 ihid->inbuf = NULL;
 ihid->rawbuf = NULL;
 ihid->cmdbuf = NULL;
 ihid->bufsize = 0;
}

static int i2c_hid_alloc_buffers(struct i2c_hid *ihid, size_t report_size)
{
 /*
 * The worst case is computed from the set_report command with a
 * reportID > 15 and the maximum report length.
 */
 int cmd_len = sizeof(__le16) + /* command register */
        sizeof(u8) + /* encoded report type/ID */
        sizeof(u8) + /* opcode */
        sizeof(u8) + /* optional 3rd byte report ID */
        sizeof(__le16) + /* data register */
        sizeof(__le16) + /* report data size */
        sizeof(u8) + /* report ID if numbered report */
        report_size;

 ihid->inbuf = kzalloc(report_size, GFP_KERNEL);
 ihid->rawbuf = kzalloc(report_size, GFP_KERNEL);
 ihid->cmdbuf = kzalloc(cmd_len, GFP_KERNEL);

 if (!ihid->inbuf || !ihid->rawbuf || !ihid->cmdbuf) {
  i2c_hid_free_buffers(ihid);
  return -ENOMEM;
 }

 ihid->bufsize = report_size;

 return 0;
}

static int i2c_hid_get_raw_report(struct hid_device *hid,
      u8 report_type, u8 report_id,
      u8 *buf, size_t count)
{
 struct i2c_client *client = hid->driver_data;
 struct i2c_hid *ihid = i2c_get_clientdata(client);
 int ret_count;

 if (report_type == HID_OUTPUT_REPORT)
  return -EINVAL;

 /*
 * In case of unnumbered reports the response from the device will
 * not have the report ID that the upper layers expect, so we need
 * to stash it the buffer ourselves and adjust the data size.
 */
 if (!report_id) {
  buf[0] = 0;
  buf++;
  count--;
 }

 ret_count = i2c_hid_get_report(ihid,
   report_type == HID_FEATURE_REPORT ? 0x03 : 0x01,
   report_id, buf, count);

 if (ret_count > 0 && !report_id)
  ret_count++;

 return ret_count;
}

static int i2c_hid_output_raw_report(struct hid_device *hid, u8 report_type,
         const u8 *buf, size_t count, bool do_set)
{
 struct i2c_client *client = hid->driver_data;
 struct i2c_hid *ihid = i2c_get_clientdata(client);
 int report_id = buf[0];
 int ret;

 if (report_type == HID_INPUT_REPORT)
  return -EINVAL;

 mutex_lock(&ihid->reset_lock);

 /*
 * Note that both numbered and unnumbered reports passed here
 * are supposed to have report ID stored in the 1st byte of the
 * buffer, so we strip it off unconditionally before passing payload
 * to i2c_hid_set_or_send_report which takes care of encoding
 * everything properly.
 */
 ret = i2c_hid_set_or_send_report(ihid,
    report_type == HID_FEATURE_REPORT ? 0x03 : 0x02,
    report_id, buf + 1, count - 1, do_set);

 if (ret >= 0)
  ret++; /* add report_id to the number of transferred bytes */

 mutex_unlock(&ihid->reset_lock);

 return ret;
}

static int i2c_hid_output_report(struct hid_device *hid, u8 *buf, size_t count)
{
 return i2c_hid_output_raw_report(hid, HID_OUTPUT_REPORT, buf, count,
      false);
}

static int i2c_hid_raw_request(struct hid_device *hid, unsigned char reportnum,
          __u8 *buf, size_t len, unsigned char rtype,
          int reqtype)
{
 switch (reqtype) {
 case HID_REQ_GET_REPORT:
  return i2c_hid_get_raw_report(hid, rtype, reportnum, buf, len);
 case HID_REQ_SET_REPORT:
  if (buf[0] != reportnum)
   return -EINVAL;
  return i2c_hid_output_raw_report(hid, rtype, buf, len, true);
 default:
  return -EIO;
 }
}

static int i2c_hid_parse(struct hid_device *hid)
{
 struct i2c_client *client = hid->driver_data;
 struct i2c_hid *ihid = i2c_get_clientdata(client);
 struct i2c_hid_desc *hdesc = &ihid->hdesc;
 char *rdesc = NULL, *use_override = NULL;
 unsigned int rsize;
 int ret;
 int tries = 3;

 i2c_hid_dbg(ihid, "entering %s\n", __func__);

 rsize = le16_to_cpu(hdesc->wReportDescLength);
 if (!rsize || rsize > HID_MAX_DESCRIPTOR_SIZE) {
  dbg_hid("weird size of report descriptor (%u)\n", rsize);
  return -EINVAL;
 }

 mutex_lock(&ihid->reset_lock);
 do {
  ret = i2c_hid_start_hwreset(ihid);
  if (ret == 0)
   ret = i2c_hid_finish_hwreset(ihid);
  else
   msleep(1000);
 } while (tries-- > 0 && ret);
 mutex_unlock(&ihid->reset_lock);

 if (ret)
  return ret;

 use_override = i2c_hid_get_dmi_hid_report_desc_override(client->name,
        &rsize);

 if (use_override) {
  rdesc = use_override;
  i2c_hid_dbg(ihid, "Using a HID report descriptor override\n");
 } else {
  rdesc = kzalloc(rsize, GFP_KERNEL);
  if (!rdesc)
   return -ENOMEM;

  i2c_hid_dbg(ihid, "asking HID report descriptor\n");

  ret = i2c_hid_read_register(ihid,
         ihid->hdesc.wReportDescRegister,
         rdesc, rsize);
  if (ret) {
   hid_err(hid, "reading report descriptor failed\n");
   goto out;
  }
 }

 i2c_hid_dbg(ihid, "Report Descriptor: %*ph\n", rsize, rdesc);

 ret = hid_parse_report(hid, rdesc, rsize);
 if (ret)
  dbg_hid("parsing report descriptor failed\n");

out:
 if (!use_override)
  kfree(rdesc);

 return ret;
}

static int i2c_hid_start(struct hid_device *hid)
{
 struct i2c_client *client = hid->driver_data;
 struct i2c_hid *ihid = i2c_get_clientdata(client);
 int ret;
 unsigned int bufsize = HID_MIN_BUFFER_SIZE;

 i2c_hid_find_max_report(hid, HID_INPUT_REPORT, &bufsize);
 i2c_hid_find_max_report(hid, HID_OUTPUT_REPORT, &bufsize);
 i2c_hid_find_max_report(hid, HID_FEATURE_REPORT, &bufsize);

 if (bufsize > ihid->bufsize) {
  disable_irq(client->irq);
  i2c_hid_free_buffers(ihid);

  ret = i2c_hid_alloc_buffers(ihid, bufsize);
  enable_irq(client->irq);

  if (ret)
   return ret;
 }

 return 0;
}

static void i2c_hid_stop(struct hid_device *hid)
{
 hid->claimed = 0;
}

static int i2c_hid_open(struct hid_device *hid)
{
 struct i2c_client *client = hid->driver_data;
 struct i2c_hid *ihid = i2c_get_clientdata(client);

 set_bit(I2C_HID_STARTED, &ihid->flags);
 return 0;
}

static void i2c_hid_close(struct hid_device *hid)
{
 struct i2c_client *client = hid->driver_data;
 struct i2c_hid *ihid = i2c_get_clientdata(client);

 clear_bit(I2C_HID_STARTED, &ihid->flags);
}

static const struct hid_ll_driver i2c_hid_ll_driver = {
 .parse = i2c_hid_parse,
 .start = i2c_hid_start,
 .stop = i2c_hid_stop,
 .open = i2c_hid_open,
 .close = i2c_hid_close,
 .output_report = i2c_hid_output_report,
 .raw_request = i2c_hid_raw_request,
};

static int i2c_hid_init_irq(struct i2c_client *client)
{
 struct i2c_hid *ihid = i2c_get_clientdata(client);
 unsigned long irqflags = 0;
 int ret;

 i2c_hid_dbg(ihid, "Requesting IRQ: %d\n", client->irq);

 if (!irq_get_trigger_type(client->irq))
  irqflags = IRQF_TRIGGER_LOW;

 ret = request_threaded_irq(client->irq, NULL, i2c_hid_irq,
       irqflags | IRQF_ONESHOT | IRQF_NO_AUTOEN,
       client->name, ihid);
 if (ret < 0) {
  dev_warn(&client->dev,
   "Could not register for %s interrupt, irq = %d,"
   " ret = %d\n",
   client->name, client->irq, ret);

  return ret;
 }

 return 0;
}

static int i2c_hid_fetch_hid_descriptor(struct i2c_hid *ihid)
{
 struct i2c_client *client = ihid->client;
 struct i2c_hid_desc *hdesc = &ihid->hdesc;
 unsigned int dsize;
 int error;

 /* i2c hid fetch using a fixed descriptor size (30 bytes) */
 if (i2c_hid_get_dmi_i2c_hid_desc_override(client->name)) {
  i2c_hid_dbg(ihid, "Using a HID descriptor override\n");
  ihid->hdesc =
   *i2c_hid_get_dmi_i2c_hid_desc_override(client->name);
 } else {
  i2c_hid_dbg(ihid, "Fetching the HID descriptor\n");
  error = i2c_hid_read_register(ihid,
           ihid->wHIDDescRegister,
           &ihid->hdesc,
           sizeof(ihid->hdesc));
  if (error) {
   dev_err(&ihid->client->dev,
    "failed to fetch HID descriptor: %d\n",
    error);
   return -ENODEV;
  }
 }

 /* Validate the length of HID descriptor, the 4 first bytes:
 * bytes 0-1 -> length
 * bytes 2-3 -> bcdVersion (has to be 1.00) */
 /* check bcdVersion == 1.0 */
 if (le16_to_cpu(hdesc->bcdVersion) != 0x0100) {
  dev_err(&ihid->client->dev,
   "unexpected HID descriptor bcdVersion (0x%04hx)\n",
   le16_to_cpu(hdesc->bcdVersion));
  return -ENODEV;
 }

 /* Descriptor length should be 30 bytes as per the specification */
 dsize = le16_to_cpu(hdesc->wHIDDescLength);
 if (dsize != sizeof(struct i2c_hid_desc)) {
  dev_err(&ihid->client->dev,
   "weird size of HID descriptor (%u)\n", dsize);
  return -ENODEV;
 }
 i2c_hid_dbg(ihid, "HID Descriptor: %*ph\n", dsize, &ihid->hdesc);
 return 0;
}

static int i2c_hid_core_power_up(struct i2c_hid *ihid)
{
 if (!ihid->ops->power_up)
  return 0;

 return ihid->ops->power_up(ihid->ops);
}

static void i2c_hid_core_power_down(struct i2c_hid *ihid)
{
 if (!ihid->ops->power_down)
  return;

 ihid->ops->power_down(ihid->ops);
}

static void i2c_hid_core_shutdown_tail(struct i2c_hid *ihid)
{
 if (!ihid->ops->shutdown_tail)
  return;

 ihid->ops->shutdown_tail(ihid->ops);
}

static void i2c_hid_core_restore_sequence(struct i2c_hid *ihid)
{
 if (!ihid->ops->restore_sequence)
  return;

 ihid->ops->restore_sequence(ihid->ops);
}

static int i2c_hid_core_suspend(struct i2c_hid *ihid, bool force_poweroff)
{
 struct i2c_client *client = ihid->client;
 struct hid_device *hid = ihid->hid;
 int ret;

 ret = hid_driver_suspend(hid, PMSG_SUSPEND);
 if (ret < 0)
  return ret;

 /* Save some power */
 if (!(ihid->quirks & I2C_HID_QUIRK_NO_SLEEP_ON_SUSPEND))
  i2c_hid_set_power(ihid, I2C_HID_PWR_SLEEP);

 disable_irq(client->irq);

 if (force_poweroff || !device_may_wakeup(&client->dev))
  i2c_hid_core_power_down(ihid);

 return 0;
}

static int i2c_hid_core_resume(struct i2c_hid *ihid)
{
 struct i2c_client *client = ihid->client;
 struct hid_device *hid = ihid->hid;
 int ret;

 if (!device_may_wakeup(&client->dev))
  i2c_hid_core_power_up(ihid);

 enable_irq(client->irq);

 /* On Goodix 27c6:0d42 wait extra time before device wakeup.
 * It's not clear why but if we send wakeup too early, the device will
 * never trigger input interrupts.
 */
 if (ihid->quirks & I2C_HID_QUIRK_DELAY_WAKEUP_AFTER_RESUME)
  msleep(1500);

 /* Instead of resetting device, simply powers the device on. This
 * solves "incomplete reports" on Raydium devices 2386:3118 and
 * 2386:4B33 and fixes various SIS touchscreens no longer sending
 * data after a suspend/resume.
 *
 * However some ALPS touchpads generate IRQ storm without reset, so
 * let's still reset them here.
 */
 if (ihid->quirks & I2C_HID_QUIRK_RESET_ON_RESUME) {
  mutex_lock(&ihid->reset_lock);
  ret = i2c_hid_start_hwreset(ihid);
  if (ret == 0)
   ret = i2c_hid_finish_hwreset(ihid);
  mutex_unlock(&ihid->reset_lock);
 } else {
  ret = i2c_hid_set_power(ihid, I2C_HID_PWR_ON);
 }

 if (ret)
  return ret;

 return hid_driver_reset_resume(hid);
}

/*
 * Check that the device exists and parse the HID descriptor.
 */
static int __i2c_hid_core_probe(struct i2c_hid *ihid)
{
 struct i2c_client *client = ihid->client;
 struct hid_device *hid = ihid->hid;
 int ret;

 ret = i2c_hid_probe_address(ihid);
 if (ret < 0) {
  i2c_hid_dbg(ihid, "nothing at this address: %d\n", ret);
  return -ENXIO;
 }

 ret = i2c_hid_fetch_hid_descriptor(ihid);
 if (ret < 0) {
  dev_err(&client->dev,
   "Failed to fetch the HID Descriptor\n");
  return ret;
 }

 hid->version = le16_to_cpu(ihid->hdesc.bcdVersion);
 hid->vendor = le16_to_cpu(ihid->hdesc.wVendorID);
 hid->product = le16_to_cpu(ihid->hdesc.wProductID);

 hid->initial_quirks |= i2c_hid_get_dmi_quirks(hid->vendor,
            hid->product);

 snprintf(hid->name, sizeof(hid->name), "%s %04X:%04X",
   client->name, (u16)hid->vendor, (u16)hid->product);
 strscpy(hid->phys, dev_name(&client->dev), sizeof(hid->phys));

 ihid->quirks = i2c_hid_lookup_quirk(hid->vendor, hid->product);

 return 0;
}

static int i2c_hid_core_register_hid(struct i2c_hid *ihid)
{
 struct i2c_client *client = ihid->client;
 struct hid_device *hid = ihid->hid;
 int ret;

 enable_irq(client->irq);

 ret = hid_add_device(hid);
 if (ret) {
  if (ret != -ENODEV)
   hid_err(client, "can't add hid device: %d\n", ret);
  disable_irq(client->irq);
  return ret;
 }

 /* At least some QTEC devices need this after initialization */
 if (ihid->quirks & I2C_HID_QUIRK_RE_POWER_ON)
  ret = i2c_hid_set_power(ihid, I2C_HID_PWR_ON);

 return ret;
}

static int i2c_hid_core_probe_panel_follower(struct i2c_hid *ihid)
{
 int ret;

 ret = i2c_hid_core_power_up(ihid);
 if (ret)
  return ret;

 ret = __i2c_hid_core_probe(ihid);
 if (ret)
  goto err_power_down;

 ret = i2c_hid_core_register_hid(ihid);
 if (ret)
  goto err_power_down;

 return 0;

err_power_down:
 i2c_hid_core_power_down(ihid);

 return ret;
}

static void ihid_core_panel_follower_work(struct work_struct *work)
{
 struct i2c_hid *ihid = container_of(work, struct i2c_hid,
         panel_follower_work);
 struct hid_device *hid = ihid->hid;
 int ret;

 /*
 * hid->version is set on the first power up. If it's still zero then
 * this is the first power on so we should perform initial power up
 * steps.
 */
 if (!hid->version)
  ret = i2c_hid_core_probe_panel_follower(ihid);
 else
  ret = i2c_hid_core_resume(ihid);

 if (ret)
  dev_warn(&ihid->client->dev, "Power on failed: %d\n", ret);
 else
  WRITE_ONCE(ihid->panel_follower_work_finished, true);

 /*
 * The work APIs provide a number of memory ordering guarantees
 * including one that says that memory writes before schedule_work()
 * are always visible to the work function, but they don't appear to
 * guarantee that a write that happened in the work is visible after
 * cancel_work_sync(). We'll add a write memory barrier here to match
 * with i2c_hid_core_panel_unpreparing() to ensure that our write to
 * panel_follower_work_finished is visible there.
 */
 smp_wmb();
}

static int i2c_hid_core_panel_follower_resume(struct drm_panel_follower *follower)
{
 struct i2c_hid *ihid = container_of(follower, struct i2c_hid, panel_follower);

 /*
 * Powering on a touchscreen can be a slow process. Queue the work to
 * the system workqueue so we don't block the panel's power up.
 */
 WRITE_ONCE(ihid->panel_follower_work_finished, false);
 schedule_work(&ihid->panel_follower_work);

 return 0;
}

static int i2c_hid_core_panel_follower_suspend(struct drm_panel_follower *follower)
{
 struct i2c_hid *ihid = container_of(follower, struct i2c_hid, panel_follower);

 cancel_work_sync(&ihid->panel_follower_work);

 /* Match with ihid_core_panel_follower_work() */
 smp_rmb();
 if (!READ_ONCE(ihid->panel_follower_work_finished))
  return 0;

 return i2c_hid_core_suspend(ihid, true);
}

static const struct drm_panel_follower_funcs
    i2c_hid_core_panel_follower_prepare_funcs = {
 .panel_prepared = i2c_hid_core_panel_follower_resume,
 .panel_unpreparing = i2c_hid_core_panel_follower_suspend,
};

static const struct drm_panel_follower_funcs
    i2c_hid_core_panel_follower_enable_funcs = {
 .panel_enabled = i2c_hid_core_panel_follower_resume,
 .panel_disabling = i2c_hid_core_panel_follower_suspend,
};

static int i2c_hid_core_register_panel_follower(struct i2c_hid *ihid)
{
 struct device *dev = &ihid->client->dev;
 int ret;

 if (ihid->hid->initial_quirks & HID_QUIRK_POWER_ON_AFTER_BACKLIGHT)
  ihid->panel_follower.funcs = &i2c_hid_core_panel_follower_enable_funcs;
 else
  ihid->panel_follower.funcs = &i2c_hid_core_panel_follower_prepare_funcs;

 /*
 * If we're not in control of our own power up/power down then we can't
 * do the logic to manage wakeups. Give a warning if a user thought
 * that was possible then force the capability off.
 */
 if (device_can_wakeup(dev)) {
  dev_warn(dev, "Can't wakeup if following panel\n");
  device_set_wakeup_capable(dev, false);
 }

 ret = drm_panel_add_follower(dev, &ihid->panel_follower);
 if (ret)
  return ret;

 return 0;
}

int i2c_hid_core_probe(struct i2c_client *client, struct i2chid_ops *ops,
         u16 hid_descriptor_address, u32 quirks)
{
 int ret;
 struct i2c_hid *ihid;
 struct hid_device *hid;

 dbg_hid("HID probe called for i2c 0x%02x\n", client->addr);

 if (!client->irq) {
  dev_err(&client->dev,
   "HID over i2c has not been provided an Int IRQ\n");
  return -EINVAL;
 }

 if (client->irq < 0) {
  if (client->irq != -EPROBE_DEFER)
   dev_err(&client->dev,
    "HID over i2c doesn't have a valid IRQ\n");
  return client->irq;
 }

 ihid = devm_kzalloc(&client->dev, sizeof(*ihid), GFP_KERNEL);
 if (!ihid)
  return -ENOMEM;

 i2c_set_clientdata(client, ihid);

 ihid->ops = ops;
 ihid->client = client;
 ihid->wHIDDescRegister = cpu_to_le16(hid_descriptor_address);
 ihid->is_panel_follower = drm_is_panel_follower(&client->dev);

 init_waitqueue_head(&ihid->wait);
 mutex_init(&ihid->cmd_lock);
 mutex_init(&ihid->reset_lock);
 INIT_WORK(&ihid->panel_follower_work, ihid_core_panel_follower_work);

 /* we need to allocate the command buffer without knowing the maximum
 * size of the reports. Let's use HID_MIN_BUFFER_SIZE, then we do the
 * real computation later. */
 ret = i2c_hid_alloc_buffers(ihid, HID_MIN_BUFFER_SIZE);
 if (ret < 0)
  return ret;
 device_enable_async_suspend(&client->dev);

 hid = hid_allocate_device();
 if (IS_ERR(hid)) {
  ret = PTR_ERR(hid);
  goto err_free_buffers;
 }

 ihid->hid = hid;

 hid->driver_data = client;
 hid->ll_driver = &i2c_hid_ll_driver;
 hid->dev.parent = &client->dev;
 hid->bus = BUS_I2C;
 hid->initial_quirks = quirks;

 /* Power on and probe unless device is a panel follower. */
 if (!ihid->is_panel_follower) {
  ret = i2c_hid_core_power_up(ihid);
  if (ret < 0)
   goto err_destroy_device;

  ret = __i2c_hid_core_probe(ihid);
  if (ret < 0)
   goto err_power_down;
 }

 ret = i2c_hid_init_irq(client);
 if (ret < 0)
  goto err_power_down;

 /*
 * If we're a panel follower, we'll register when the panel turns on;
 * otherwise we do it right away.
 */
 if (ihid->is_panel_follower)
  ret = i2c_hid_core_register_panel_follower(ihid);
 else
  ret = i2c_hid_core_register_hid(ihid);
 if (ret)
  goto err_free_irq;

 return 0;

err_free_irq:
 free_irq(client->irq, ihid);
err_power_down:
 if (!ihid->is_panel_follower)
  i2c_hid_core_power_down(ihid);
err_destroy_device:
 hid_destroy_device(hid);
err_free_buffers:
 i2c_hid_free_buffers(ihid);

 return ret;
}
EXPORT_SYMBOL_GPL(i2c_hid_core_probe);

void i2c_hid_core_remove(struct i2c_client *client)
{
 struct i2c_hid *ihid = i2c_get_clientdata(client);
 struct hid_device *hid;

 /*
 * If we're a follower, the act of unfollowing will cause us to be
 * powered down. Otherwise we need to manually do it.
 */
 if (ihid->is_panel_follower)
  drm_panel_remove_follower(&ihid->panel_follower);
 else
  i2c_hid_core_suspend(ihid, true);

 hid = ihid->hid;
 hid_destroy_device(hid);

 free_irq(client->irq, ihid);

 if (ihid->bufsize)
  i2c_hid_free_buffers(ihid);
}
EXPORT_SYMBOL_GPL(i2c_hid_core_remove);

void i2c_hid_core_shutdown(struct i2c_client *client)
{
 struct i2c_hid *ihid = i2c_get_clientdata(client);

 i2c_hid_set_power(ihid, I2C_HID_PWR_SLEEP);
 free_irq(client->irq, ihid);

 i2c_hid_core_shutdown_tail(ihid);
}
EXPORT_SYMBOL_GPL(i2c_hid_core_shutdown);

static int i2c_hid_core_pm_suspend(struct device *dev)
{
 struct i2c_client *client = to_i2c_client(dev);
 struct i2c_hid *ihid = i2c_get_clientdata(client);

 if (ihid->is_panel_follower)
  return 0;

 return i2c_hid_core_suspend(ihid, false);
}

static int i2c_hid_core_pm_resume(struct device *dev)
{
 struct i2c_client *client = to_i2c_client(dev);
 struct i2c_hid *ihid = i2c_get_clientdata(client);

 if (ihid->is_panel_follower)
  return 0;

 return i2c_hid_core_resume(ihid);
}

static int i2c_hid_core_pm_restore(struct device *dev)
{
 struct i2c_client *client = to_i2c_client(dev);
 struct i2c_hid *ihid = i2c_get_clientdata(client);

 if (ihid->is_panel_follower)
  return 0;

 i2c_hid_core_restore_sequence(ihid);

 return i2c_hid_core_resume(ihid);
}

const struct dev_pm_ops i2c_hid_core_pm = {
 .suspend = pm_sleep_ptr(i2c_hid_core_pm_suspend),
 .resume = pm_sleep_ptr(i2c_hid_core_pm_resume),
 .freeze = pm_sleep_ptr(i2c_hid_core_pm_suspend),
 .thaw = pm_sleep_ptr(i2c_hid_core_pm_resume),
 .poweroff = pm_sleep_ptr(i2c_hid_core_pm_suspend),
 .restore = pm_sleep_ptr(i2c_hid_core_pm_restore),
};
EXPORT_SYMBOL_GPL(i2c_hid_core_pm);

MODULE_DESCRIPTION("HID over I2C core driver");
MODULE_AUTHOR("Benjamin Tissoires ");
MODULE_LICENSE("GPL");