Merge branch 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel...

[cris-mirror.git] / drivers / hid / i2c-hid / i2c-hid.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/delay.h>
#include <linux/slab.h>
#include <linux/pm.h>
#include <linux/pm_runtime.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/acpi.h>
#include <linux/of.h>
#include <linux/gpio/consumer.h>

#include <linux/i2c/i2c-hid.h>

/* flags */
#define I2C_HID_STARTED         0
#define I2C_HID_RESET_PENDING   1
#define I2C_HID_READ_PENDING    2

#define I2C_HID_PWR_ON          0x00
#define I2C_HID_PWR_SLEEP       0x01

/* debug option */
static bool debug;
module_param(debug, bool, 0444);
MODULE_PARM_DESC(debug, "print a lot of debug information");

#define i2c_hid_dbg(ihid, fmt, arg...)                                    \
do {                                                                      \
        if (debug)                                                        \
                dev_printk(KERN_DEBUG, &(ihid)->client->dev, fmt, ##arg); \
} while (0)

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;

struct i2c_hid_cmd {
        unsigned int registerIndex;
        __u8 opcode;
        unsigned int length;
        bool wait;
};

union command {
        u8 data[0];
        struct cmd {
                __le16 reg;
                __u8 reportTypeID;
                __u8 opcode;
        } __packed c;
};

#define I2C_HID_CMD(opcode_) \
        .opcode = opcode_, .length = 4, \
        .registerIndex = offsetof(struct i2c_hid_desc, wCommandRegister)

/* fetch HID descriptor */
static const struct i2c_hid_cmd hid_descr_cmd = { .length = 2 };
/* fetch report descriptors */
static const struct i2c_hid_cmd hid_report_descr_cmd = {
                .registerIndex = offsetof(struct i2c_hid_desc,
                        wReportDescRegister),
                .opcode = 0x00,
                .length = 2 };
/* commands */
static const struct i2c_hid_cmd hid_reset_cmd =         { I2C_HID_CMD(0x01),
                                                          .wait = true };
static const struct i2c_hid_cmd hid_get_report_cmd =    { I2C_HID_CMD(0x02) };
static const struct i2c_hid_cmd hid_set_report_cmd =    { I2C_HID_CMD(0x03) };
static const struct i2c_hid_cmd hid_set_power_cmd =     { I2C_HID_CMD(0x08) };
static const struct i2c_hid_cmd hid_no_cmd =            { .length = 0 };

/*
 * These definitions are not used here, but are defined by the spec.
 * Keeping them here for documentation purposes.
 *
 * static const struct i2c_hid_cmd hid_get_idle_cmd = { I2C_HID_CMD(0x04) };
 * static const struct i2c_hid_cmd hid_set_idle_cmd = { I2C_HID_CMD(0x05) };
 * static const struct i2c_hid_cmd hid_get_protocol_cmd = { I2C_HID_CMD(0x06) };
 * static const struct i2c_hid_cmd hid_set_protocol_cmd = { I2C_HID_CMD(0x07) };
 */

static DEFINE_MUTEX(i2c_hid_open_mut);

/* The main device structure */
struct i2c_hid {
        struct i2c_client       *client;        /* i2c client */
        struct hid_device       *hid;   /* pointer to corresponding HID dev */
        union {
                __u8 hdesc_buffer[sizeof(struct i2c_hid_desc)];
                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 */
        char                    *inbuf;         /* Input buffer */
        char                    *rawbuf;        /* Raw Input buffer */
        char                    *cmdbuf;        /* Command buffer */
        char                    *argsbuf;       /* Command arguments buffer */

        unsigned long           flags;          /* device flags */

        wait_queue_head_t       wait;           /* For waiting the interrupt */
        struct gpio_desc        *desc;
        int                     irq;

        struct i2c_hid_platform_data pdata;

        bool                    irq_wake_enabled;
        struct mutex            reset_lock;
};

static int __i2c_hid_command(struct i2c_client *client,
                const struct i2c_hid_cmd *command, u8 reportID,
                u8 reportType, u8 *args, int args_len,
                unsigned char *buf_recv, int data_len)
{
        struct i2c_hid *ihid = i2c_get_clientdata(client);
        union command *cmd = (union command *)ihid->cmdbuf;
        int ret;
        struct i2c_msg msg[2];
        int msg_num = 1;

        int length = command->length;
        bool wait = command->wait;
        unsigned int registerIndex = command->registerIndex;

        /* special case for hid_descr_cmd */
        if (command == &hid_descr_cmd) {
                cmd->c.reg = ihid->wHIDDescRegister;
        } else {
                cmd->data[0] = ihid->hdesc_buffer[registerIndex];
                cmd->data[1] = ihid->hdesc_buffer[registerIndex + 1];
        }

        if (length > 2) {
                cmd->c.opcode = command->opcode;
                cmd->c.reportTypeID = reportID | reportType << 4;
        }

        memcpy(cmd->data + length, args, args_len);
        length += args_len;

        i2c_hid_dbg(ihid, "%s: cmd=%*ph\n", __func__, length, cmd->data);

        msg[0].addr = client->addr;
        msg[0].flags = client->flags & I2C_M_TEN;
        msg[0].len = length;
        msg[0].buf = cmd->data;
        if (data_len > 0) {
                msg[1].addr = client->addr;
                msg[1].flags = client->flags & I2C_M_TEN;
                msg[1].flags |= I2C_M_RD;
                msg[1].len = data_len;
                msg[1].buf = buf_recv;
                msg_num = 2;
                set_bit(I2C_HID_READ_PENDING, &ihid->flags);
        }

        if (wait)
                set_bit(I2C_HID_RESET_PENDING, &ihid->flags);

        ret = i2c_transfer(client->adapter, msg, msg_num);

        if (data_len > 0)
                clear_bit(I2C_HID_READ_PENDING, &ihid->flags);

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

        ret = 0;

        if (wait) {
                i2c_hid_dbg(ihid, "%s: waiting...\n", __func__);
                if (!wait_event_timeout(ihid->wait,
                                !test_bit(I2C_HID_RESET_PENDING, &ihid->flags),
                                msecs_to_jiffies(5000)))
                        ret = -ENODATA;
                i2c_hid_dbg(ihid, "%s: finished.\n", __func__);
        }

        return ret;
}

static int i2c_hid_command(struct i2c_client *client,
                const struct i2c_hid_cmd *command,
                unsigned char *buf_recv, int data_len)
{
        return __i2c_hid_command(client, command, 0, 0, NULL, 0,
                                buf_recv, data_len);
}

static int i2c_hid_get_report(struct i2c_client *client, u8 reportType,
                u8 reportID, unsigned char *buf_recv, int data_len)
{
        struct i2c_hid *ihid = i2c_get_clientdata(client);
        u8 args[3];
        int ret;
        int args_len = 0;
        u16 readRegister = le16_to_cpu(ihid->hdesc.wDataRegister);

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

        if (reportID >= 0x0F) {
                args[args_len++] = reportID;
                reportID = 0x0F;
        }

        args[args_len++] = readRegister & 0xFF;
        args[args_len++] = readRegister >> 8;

        ret = __i2c_hid_command(client, &hid_get_report_cmd, reportID,
                reportType, args, args_len, buf_recv, data_len);
        if (ret) {
                dev_err(&client->dev,
                        "failed to retrieve report from device.\n");
                return ret;
        }

        return 0;
}

/**
 * i2c_hid_set_or_send_report: forward an incoming report to the device
 * @client: the i2c_client of the device
 * @reportType: 0x03 for HID_FEATURE_REPORT ; 0x02 for HID_OUTPUT_REPORT
 * @reportID: the report ID
 * @buf: the actual data to transfer, without the report ID
 * @len: size of buf
 * @use_data: true: use SET_REPORT HID command, false: send plain OUTPUT report
 */
static int i2c_hid_set_or_send_report(struct i2c_client *client, u8 reportType,
                u8 reportID, unsigned char *buf, size_t data_len, bool use_data)
{
        struct i2c_hid *ihid = i2c_get_clientdata(client);
        u8 *args = ihid->argsbuf;
        const struct i2c_hid_cmd *hidcmd;
        int ret;
        u16 dataRegister = le16_to_cpu(ihid->hdesc.wDataRegister);
        u16 outputRegister = le16_to_cpu(ihid->hdesc.wOutputRegister);
        u16 maxOutputLength = le16_to_cpu(ihid->hdesc.wMaxOutputLength);
        u16 size;
        int args_len;
        int index = 0;

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

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

        size =          2                       /* size */ +
                        (reportID ? 1 : 0)      /* reportID */ +
                        data_len                /* buf */;
        args_len =      (reportID >= 0x0F ? 1 : 0) /* optional third byte */ +
                        2                       /* dataRegister */ +
                        size                    /* args */;

        if (!use_data && maxOutputLength == 0)
                return -ENOSYS;

        if (reportID >= 0x0F) {
                args[index++] = reportID;
                reportID = 0x0F;
        }

        /*
         * use the data register for feature reports or if the device does not
         * support the output register
         */
        if (use_data) {
                args[index++] = dataRegister & 0xFF;
                args[index++] = dataRegister >> 8;
                hidcmd = &hid_set_report_cmd;
        } else {
                args[index++] = outputRegister & 0xFF;
                args[index++] = outputRegister >> 8;
                hidcmd = &hid_no_cmd;
        }

        args[index++] = size & 0xFF;
        args[index++] = size >> 8;

        if (reportID)
                args[index++] = reportID;

        memcpy(&args[index], buf, data_len);

        ret = __i2c_hid_command(client, hidcmd, reportID,
                reportType, args, args_len, NULL, 0);
        if (ret) {
                dev_err(&client->dev, "failed to set a report to device.\n");
                return ret;
        }

        return data_len;
}

static int i2c_hid_set_power(struct i2c_client *client, int power_state)
{
        struct i2c_hid *ihid = i2c_get_clientdata(client);
        int ret;

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

        ret = __i2c_hid_command(client, &hid_set_power_cmd, power_state,
                0, NULL, 0, NULL, 0);
        if (ret)
                dev_err(&client->dev, "failed to change power setting.\n");

        return ret;
}

static int i2c_hid_hwreset(struct i2c_client *client)
{
        struct i2c_hid *ihid = i2c_get_clientdata(client);
        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.
         */
        mutex_lock(&ihid->reset_lock);

        ret = i2c_hid_set_power(client, I2C_HID_PWR_ON);
        if (ret)
                goto out_unlock;

        i2c_hid_dbg(ihid, "resetting...\n");

        ret = i2c_hid_command(client, &hid_reset_cmd, NULL, 0);
        if (ret) {
                dev_err(&client->dev, "failed to reset device.\n");
                i2c_hid_set_power(client, I2C_HID_PWR_SLEEP);
        }

out_unlock:
        mutex_unlock(&ihid->reset_lock);
        return ret;
}

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

        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;
        }

        ret_size = ihid->inbuf[0] | ihid->inbuf[1] << 8;

        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 (ret_size > size) {
                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))
                hid_input_report(ihid->hid, HID_INPUT_REPORT, ihid->inbuf + 2,
                                ret_size - 2, 1);

        return;
}

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

        if (test_bit(I2C_HID_READ_PENDING, &ihid->flags))
                return IRQ_HANDLED;

        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;
}

static void i2c_hid_init_report(struct hid_report *report, u8 *buffer,
        size_t bufsize)
{
        struct hid_device *hid = report->device;
        struct i2c_client *client = hid->driver_data;
        struct i2c_hid *ihid = i2c_get_clientdata(client);
        unsigned int size, ret_size;

        size = i2c_hid_get_report_length(report);
        if (i2c_hid_get_report(client,
                        report->type == HID_FEATURE_REPORT ? 0x03 : 0x01,
                        report->id, buffer, size))
                return;

        i2c_hid_dbg(ihid, "report (len=%d): %*ph\n", size, size, buffer);

        ret_size = buffer[0] | (buffer[1] << 8);

        if (ret_size != size) {
                dev_err(&client->dev, "error in %s size:%d / ret_size:%d\n",
                        __func__, size, ret_size);
                return;
        }

        /* hid->driver_lock is held as we are in probe function,
         * we just need to setup the input fields, so using
         * hid_report_raw_event is safe. */
        hid_report_raw_event(hid, report->type, buffer + 2, size - 2, 1);
}

/*
 * Initialize all reports
 */
static void i2c_hid_init_reports(struct hid_device *hid)
{
        struct hid_report *report;
        struct i2c_client *client = hid->driver_data;
        struct i2c_hid *ihid = i2c_get_clientdata(client);
        u8 *inbuf = kzalloc(ihid->bufsize, GFP_KERNEL);

        if (!inbuf) {
                dev_err(&client->dev, "can not retrieve initial reports\n");
                return;
        }

        /*
         * The device must be powered on while we fetch initial reports
         * from it.
         */
        pm_runtime_get_sync(&client->dev);

        list_for_each_entry(report,
                &hid->report_enum[HID_FEATURE_REPORT].report_list, list)
                i2c_hid_init_report(report, inbuf, ihid->bufsize);

        pm_runtime_put(&client->dev);

        kfree(inbuf);
}

/*
 * 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->argsbuf);
        kfree(ihid->cmdbuf);
        ihid->inbuf = NULL;
        ihid->rawbuf = NULL;
        ihid->cmdbuf = NULL;
        ihid->argsbuf = 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 args_len = sizeof(__u8) + /* optional ReportID byte */
                       sizeof(__u16) + /* data register */
                       sizeof(__u16) + /* size of the report */
                       report_size; /* report */

        ihid->inbuf = kzalloc(report_size, GFP_KERNEL);
        ihid->rawbuf = kzalloc(report_size, GFP_KERNEL);
        ihid->argsbuf = kzalloc(args_len, GFP_KERNEL);
        ihid->cmdbuf = kzalloc(sizeof(union command) + args_len, GFP_KERNEL);

        if (!ihid->inbuf || !ihid->rawbuf || !ihid->argsbuf || !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,
                unsigned char report_number, __u8 *buf, size_t count,
                unsigned char report_type)
{
        struct i2c_client *client = hid->driver_data;
        struct i2c_hid *ihid = i2c_get_clientdata(client);
        size_t ret_count, ask_count;
        int ret;

        if (report_type == HID_OUTPUT_REPORT)
                return -EINVAL;

        /* +2 bytes to include the size of the reply in the query buffer */
        ask_count = min(count + 2, (size_t)ihid->bufsize);

        ret = i2c_hid_get_report(client,
                        report_type == HID_FEATURE_REPORT ? 0x03 : 0x01,
                        report_number, ihid->rawbuf, ask_count);

        if (ret < 0)
                return ret;

        ret_count = ihid->rawbuf[0] | (ihid->rawbuf[1] << 8);

        if (ret_count <= 2)
                return 0;

        ret_count = min(ret_count, ask_count);

        /* The query buffer contains the size, dropping it in the reply */
        count = min(count, ret_count - 2);
        memcpy(buf, ihid->rawbuf + 2, count);

        return count;
}

static int i2c_hid_output_raw_report(struct hid_device *hid, __u8 *buf,
                size_t count, unsigned char report_type, bool use_data)
{
        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);

        if (report_id) {
                buf++;
                count--;
        }

        ret = i2c_hid_set_or_send_report(client,
                                report_type == HID_FEATURE_REPORT ? 0x03 : 0x02,
                                report_id, buf, count, use_data);

        if (report_id && ret >= 0)
                ret++; /* add report_id to the number of transfered 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, buf, count, HID_OUTPUT_REPORT,
                        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, reportnum, buf, len, rtype);
        case HID_REQ_SET_REPORT:
                if (buf[0] != reportnum)
                        return -EINVAL;
                return i2c_hid_output_raw_report(hid, buf, len, rtype, 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;
        unsigned int rsize;
        char *rdesc;
        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;
        }

        do {
                ret = i2c_hid_hwreset(client);
                if (ret)
                        msleep(1000);
        } while (tries-- > 0 && ret);

        if (ret)
                return ret;

        rdesc = kzalloc(rsize, GFP_KERNEL);

        if (!rdesc) {
                dbg_hid("couldn't allocate rdesc memory\n");
                return -ENOMEM;
        }

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

        ret = i2c_hid_command(client, &hid_report_descr_cmd, rdesc, rsize);
        if (ret) {
                hid_err(hid, "reading report descriptor failed\n");
                kfree(rdesc);
                return -EIO;
        }

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

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

        return 0;
}

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) {
                i2c_hid_free_buffers(ihid);

                ret = i2c_hid_alloc_buffers(ihid, bufsize);

                if (ret)
                        return ret;
        }

        if (!(hid->quirks & HID_QUIRK_NO_INIT_REPORTS))
                i2c_hid_init_reports(hid);

        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);
        int ret = 0;

        mutex_lock(&i2c_hid_open_mut);
        if (!hid->open++) {
                ret = pm_runtime_get_sync(&client->dev);
                if (ret < 0) {
                        hid->open--;
                        goto done;
                }
                set_bit(I2C_HID_STARTED, &ihid->flags);
        }
done:
        mutex_unlock(&i2c_hid_open_mut);
        return ret < 0 ? ret : 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);

        /* protecting hid->open to make sure we don't restart
         * data acquistion due to a resumption we no longer
         * care about
         */
        mutex_lock(&i2c_hid_open_mut);
        if (!--hid->open) {
                clear_bit(I2C_HID_STARTED, &ihid->flags);

                /* Save some power */
                pm_runtime_put(&client->dev);
        }
        mutex_unlock(&i2c_hid_open_mut);
}

static int i2c_hid_power(struct hid_device *hid, int lvl)
{
        struct i2c_client *client = hid->driver_data;
        struct i2c_hid *ihid = i2c_get_clientdata(client);

        i2c_hid_dbg(ihid, "%s lvl:%d\n", __func__, lvl);

        switch (lvl) {
        case PM_HINT_FULLON:
                pm_runtime_get_sync(&client->dev);
                break;
        case PM_HINT_NORMAL:
                pm_runtime_put(&client->dev);
                break;
        }
        return 0;
}

static 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,
        .power = i2c_hid_power,
        .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);
        int ret;

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

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

        /* i2c hid fetch using a fixed descriptor size (30 bytes) */
        i2c_hid_dbg(ihid, "Fetching the HID descriptor\n");
        ret = i2c_hid_command(client, &hid_descr_cmd, ihid->hdesc_buffer,
                                sizeof(struct i2c_hid_desc));
        if (ret) {
                dev_err(&client->dev, "hid_descr_cmd failed\n");
                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(&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(&client->dev, "weird size of HID descriptor (%u)\n",
                        dsize);
                return -ENODEV;
        }
        i2c_hid_dbg(ihid, "HID Descriptor: %*ph\n", dsize, ihid->hdesc_buffer);
        return 0;
}

#ifdef CONFIG_ACPI

/* Default GPIO mapping */
static const struct acpi_gpio_params i2c_hid_irq_gpio = { 0, 0, true };
static const struct acpi_gpio_mapping i2c_hid_acpi_gpios[] = {
        { "gpios", &i2c_hid_irq_gpio, 1 },
        { },
};

static int i2c_hid_acpi_pdata(struct i2c_client *client,
                struct i2c_hid_platform_data *pdata)
{
        static u8 i2c_hid_guid[] = {
                0xF7, 0xF6, 0xDF, 0x3C, 0x67, 0x42, 0x55, 0x45,
                0xAD, 0x05, 0xB3, 0x0A, 0x3D, 0x89, 0x38, 0xDE,
        };
        union acpi_object *obj;
        struct acpi_device *adev;
        acpi_handle handle;
        int ret;

        handle = ACPI_HANDLE(&client->dev);
        if (!handle || acpi_bus_get_device(handle, &adev))
                return -ENODEV;

        obj = acpi_evaluate_dsm_typed(handle, i2c_hid_guid, 1, 1, NULL,
                                      ACPI_TYPE_INTEGER);
        if (!obj) {
                dev_err(&client->dev, "device _DSM execution failed\n");
                return -ENODEV;
        }

        pdata->hid_descriptor_address = obj->integer.value;
        ACPI_FREE(obj);

        /* GPIOs are optional */
        ret = acpi_dev_add_driver_gpios(adev, i2c_hid_acpi_gpios);
        return ret < 0 && ret != -ENXIO ? ret : 0;
}

static const struct acpi_device_id i2c_hid_acpi_match[] = {
        {"ACPI0C50", 0 },
        {"PNP0C50", 0 },
        { },
};
MODULE_DEVICE_TABLE(acpi, i2c_hid_acpi_match);
#else
static inline int i2c_hid_acpi_pdata(struct i2c_client *client,
                struct i2c_hid_platform_data *pdata)
{
        return -ENODEV;
}
#endif

#ifdef CONFIG_OF
static int i2c_hid_of_probe(struct i2c_client *client,
                struct i2c_hid_platform_data *pdata)
{
        struct device *dev = &client->dev;
        u32 val;
        int ret;

        ret = of_property_read_u32(dev->of_node, "hid-descr-addr", &val);
        if (ret) {
                dev_err(&client->dev, "HID register address not provided\n");
                return -ENODEV;
        }
        if (val >> 16) {
                dev_err(&client->dev, "Bad HID register address: 0x%08x\n",
                        val);
                return -EINVAL;
        }
        pdata->hid_descriptor_address = val;

        return 0;
}

static const struct of_device_id i2c_hid_of_match[] = {
        { .compatible = "hid-over-i2c" },
        {},
};
MODULE_DEVICE_TABLE(of, i2c_hid_of_match);
#else
static inline int i2c_hid_of_probe(struct i2c_client *client,
                struct i2c_hid_platform_data *pdata)
{
        return -ENODEV;
}
#endif

static int i2c_hid_probe(struct i2c_client *client,
                         const struct i2c_device_id *dev_id)
{
        int ret;
        struct i2c_hid *ihid;
        struct hid_device *hid;
        __u16 hidRegister;
        struct i2c_hid_platform_data *platform_data = client->dev.platform_data;

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

        ihid = kzalloc(sizeof(struct i2c_hid), GFP_KERNEL);
        if (!ihid)
                return -ENOMEM;

        if (client->dev.of_node) {
                ret = i2c_hid_of_probe(client, &ihid->pdata);
                if (ret)
                        goto err;
        } else if (!platform_data) {
                ret = i2c_hid_acpi_pdata(client, &ihid->pdata);
                if (ret) {
                        dev_err(&client->dev,
                                "HID register address not provided\n");
                        goto err;
                }
        } else {
                ihid->pdata = *platform_data;
        }

        if (client->irq > 0) {
                ihid->irq = client->irq;
        } else if (ACPI_COMPANION(&client->dev)) {
                ihid->desc = gpiod_get(&client->dev, NULL, GPIOD_IN);
                if (IS_ERR(ihid->desc)) {
                        dev_err(&client->dev, "Failed to get GPIO interrupt\n");
                        return PTR_ERR(ihid->desc);
                }

                ihid->irq = gpiod_to_irq(ihid->desc);
                if (ihid->irq < 0) {
                        gpiod_put(ihid->desc);
                        dev_err(&client->dev, "Failed to convert GPIO to IRQ\n");
                        return ihid->irq;
                }
        }

        i2c_set_clientdata(client, ihid);

        ihid->client = client;

        hidRegister = ihid->pdata.hid_descriptor_address;
        ihid->wHIDDescRegister = cpu_to_le16(hidRegister);

        init_waitqueue_head(&ihid->wait);
        mutex_init(&ihid->reset_lock);

        /* 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)
                goto err;

        pm_runtime_get_noresume(&client->dev);
        pm_runtime_set_active(&client->dev);
        pm_runtime_enable(&client->dev);
        device_enable_async_suspend(&client->dev);

        ret = i2c_hid_fetch_hid_descriptor(ihid);
        if (ret < 0)
                goto err_pm;

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

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

        ihid->hid = hid;

        hid->driver_data = client;
        hid->ll_driver = &i2c_hid_ll_driver;
        hid->dev.parent = &client->dev;
        hid->bus = BUS_I2C;
        hid->version = le16_to_cpu(ihid->hdesc.bcdVersion);
        hid->vendor = le16_to_cpu(ihid->hdesc.wVendorID);
        hid->product = le16_to_cpu(ihid->hdesc.wProductID);

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

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

        pm_runtime_put(&client->dev);
        return 0;

err_mem_free:
        hid_destroy_device(hid);

err_irq:
        free_irq(ihid->irq, ihid);

err_pm:
        pm_runtime_put_noidle(&client->dev);
        pm_runtime_disable(&client->dev);

err:
        if (ihid->desc)
                gpiod_put(ihid->desc);

        i2c_hid_free_buffers(ihid);
        kfree(ihid);
        return ret;
}

static int i2c_hid_remove(struct i2c_client *client)
{
        struct i2c_hid *ihid = i2c_get_clientdata(client);
        struct hid_device *hid;

        pm_runtime_get_sync(&client->dev);
        pm_runtime_disable(&client->dev);
        pm_runtime_set_suspended(&client->dev);
        pm_runtime_put_noidle(&client->dev);

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

        free_irq(ihid->irq, ihid);

        if (ihid->bufsize)
                i2c_hid_free_buffers(ihid);

        if (ihid->desc)
                gpiod_put(ihid->desc);

        kfree(ihid);

        acpi_dev_remove_driver_gpios(ACPI_COMPANION(&client->dev));

        return 0;
}

static void i2c_hid_shutdown(struct i2c_client *client)
{
        struct i2c_hid *ihid = i2c_get_clientdata(client);

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

#ifdef CONFIG_PM_SLEEP
static int i2c_hid_suspend(struct device *dev)
{
        struct i2c_client *client = to_i2c_client(dev);
        struct i2c_hid *ihid = i2c_get_clientdata(client);
        struct hid_device *hid = ihid->hid;
        int ret;
        int wake_status;

        if (hid->driver && hid->driver->suspend) {
                /*
                 * Wake up the device so that IO issues in
                 * HID driver's suspend code can succeed.
                 */
                ret = pm_runtime_resume(dev);
                if (ret < 0)
                        return ret;

                ret = hid->driver->suspend(hid, PMSG_SUSPEND);
                if (ret < 0)
                        return ret;
        }

        if (!pm_runtime_suspended(dev)) {
                /* Save some power */
                i2c_hid_set_power(client, I2C_HID_PWR_SLEEP);

                disable_irq(ihid->irq);
        }

        if (device_may_wakeup(&client->dev)) {
                wake_status = enable_irq_wake(ihid->irq);
                if (!wake_status)
                        ihid->irq_wake_enabled = true;
                else
                        hid_warn(hid, "Failed to enable irq wake: %d\n",
                                wake_status);
        }

        return 0;
}

static int i2c_hid_resume(struct device *dev)
{
        int ret;
        struct i2c_client *client = to_i2c_client(dev);
        struct i2c_hid *ihid = i2c_get_clientdata(client);
        struct hid_device *hid = ihid->hid;
        int wake_status;

        if (device_may_wakeup(&client->dev) && ihid->irq_wake_enabled) {
                wake_status = disable_irq_wake(ihid->irq);
                if (!wake_status)
                        ihid->irq_wake_enabled = false;
                else
                        hid_warn(hid, "Failed to disable irq wake: %d\n",
                                wake_status);
        }

        /* We'll resume to full power */
        pm_runtime_disable(dev);
        pm_runtime_set_active(dev);
        pm_runtime_enable(dev);

        enable_irq(ihid->irq);
        ret = i2c_hid_hwreset(client);
        if (ret)
                return ret;

        if (hid->driver && hid->driver->reset_resume) {
                ret = hid->driver->reset_resume(hid);
                return ret;
        }

        return 0;
}
#endif

#ifdef CONFIG_PM
static int i2c_hid_runtime_suspend(struct device *dev)
{
        struct i2c_client *client = to_i2c_client(dev);
        struct i2c_hid *ihid = i2c_get_clientdata(client);

        i2c_hid_set_power(client, I2C_HID_PWR_SLEEP);
        disable_irq(ihid->irq);
        return 0;
}

static int i2c_hid_runtime_resume(struct device *dev)
{
        struct i2c_client *client = to_i2c_client(dev);
        struct i2c_hid *ihid = i2c_get_clientdata(client);

        enable_irq(ihid->irq);
        i2c_hid_set_power(client, I2C_HID_PWR_ON);
        return 0;
}
#endif

static const struct dev_pm_ops i2c_hid_pm = {
        SET_SYSTEM_SLEEP_PM_OPS(i2c_hid_suspend, i2c_hid_resume)
        SET_RUNTIME_PM_OPS(i2c_hid_runtime_suspend, i2c_hid_runtime_resume,
                           NULL)
};

static const struct i2c_device_id i2c_hid_id_table[] = {
        { "hid", 0 },
        { "hid-over-i2c", 0 },
        { },
};
MODULE_DEVICE_TABLE(i2c, i2c_hid_id_table);


static struct i2c_driver i2c_hid_driver = {
        .driver = {
                .name   = "i2c_hid",
                .pm     = &i2c_hid_pm,
                .acpi_match_table = ACPI_PTR(i2c_hid_acpi_match),
                .of_match_table = of_match_ptr(i2c_hid_of_match),
        },

        .probe          = i2c_hid_probe,
        .remove         = i2c_hid_remove,
        .shutdown       = i2c_hid_shutdown,
        .id_table       = i2c_hid_id_table,
};

module_i2c_driver(i2c_hid_driver);

MODULE_DESCRIPTION("HID over I2C core driver");
MODULE_AUTHOR("Benjamin Tissoires <benjamin.tissoires@gmail.com>");
MODULE_LICENSE("GPL");