Re: [PATCH v1] i2c-hid: introduce HID over i2c specification implementation

[Shubhrajyoti Datta]

On Fri, Sep 14, 2012 at 7:11 PM, benjamin.tissoires
<benjamin.tissoires@xxxxxxxxx> wrote:
> From: Benjamin Tissoires <benjamin.tissoires@xxxxxxx>
>
> Microsoft published the protocol specification of HID over i2c:
> http://msdn.microsoft.com/en-us/library/windows/hardware/hh852380.aspx
>
> This patch introduces an implementation of this protocol.
>
> This implementation does not includes the ACPI part of the specification.
> This will come when ACPI 5.0 devices will be available.
>
> Once the ACPI part will be done, OEM will not have to declare HID over I2C
> devices in their platform specific driver.
>
> Signed-off-by: Benjamin Tissoires <benjamin.tissoires@xxxxxxx>
> ---
>
> Hi,
>
> this is finally my first implementation of HID over I2C.
>
> This has been tested on an Elan Microelectronics HID over I2C device, with
> a Samsung Exynos 4412 board.
>
> Any comments are welcome.
>
> Cheers,
> Benjamin
>
>  drivers/i2c/Kconfig         |    8 +
>  drivers/i2c/Makefile        |    1 +
>  drivers/i2c/i2c-hid.c       | 1027 +++++++++++++++++++++++++++++++++++++++++++
>  include/linux/i2c/i2c-hid.h |   35 ++
>  4 files changed, 1071 insertions(+)
>  create mode 100644 drivers/i2c/i2c-hid.c
>  create mode 100644 include/linux/i2c/i2c-hid.h
>
> diff --git a/drivers/i2c/Kconfig b/drivers/i2c/Kconfig
> index 5a3bb3d..5adf65a 100644
> --- a/drivers/i2c/Kconfig
> +++ b/drivers/i2c/Kconfig
> @@ -47,6 +47,14 @@ config I2C_CHARDEV
>           This support is also available as a module.  If so, the module
>           will be called i2c-dev.
>
> +config I2C_HID
> +       tristate "HID over I2C bus"
> +       help
> +         Say Y here to use the HID over i2c protocol implementation.
> +
> +         This support is also available as a module.  If so, the module
> +         will be called i2c-hid.
> +
>  config I2C_MUX
>         tristate "I2C bus multiplexing support"
>         help
> diff --git a/drivers/i2c/Makefile b/drivers/i2c/Makefile
> index beee6b2..8f38116 100644
> --- a/drivers/i2c/Makefile
> +++ b/drivers/i2c/Makefile
> @@ -6,6 +6,7 @@ obj-$(CONFIG_I2C_BOARDINFO)     += i2c-boardinfo.o
>  obj-$(CONFIG_I2C)              += i2c-core.o
>  obj-$(CONFIG_I2C_SMBUS)                += i2c-smbus.o
>  obj-$(CONFIG_I2C_CHARDEV)      += i2c-dev.o
> +obj-$(CONFIG_I2C_HID)          += i2c-hid.o
>  obj-$(CONFIG_I2C_MUX)          += i2c-mux.o
>  obj-y                          += algos/ busses/ muxes/
>
> diff --git a/drivers/i2c/i2c-hid.c b/drivers/i2c/i2c-hid.c
> new file mode 100644
> index 0000000..eb17d8c
> --- /dev/null
> +++ b/drivers/i2c/i2c-hid.c
> @@ -0,0 +1,1027 @@
> +/*
> + * HID over I2C protocol implementation
> + *
> + * Copyright (c) 2012 Benjamin Tissoires <benjamin.tissoires@xxxxxxxxx>
> + * Copyright (c) 2012 Ecole Nationale de l'Aviation Civile, France
> + *
> + * This code is partly based on "USB HID support for Linux":
> + *
> + *  Copyright (c) 1999 Andreas Gal
> + *  Copyright (c) 2000-2005 Vojtech Pavlik <vojtech@xxxxxxx>
> + *  Copyright (c) 2005 Michael Haboustak <mike-@xxxxxxxxxxxx> 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/irq.h>
> +#include <linux/gpio.h>
> +#include <linux/interrupt.h>
> +#include <linux/input.h>
> +#include <linux/delay.h>
> +#include <linux/slab.h>
> +#include <linux/pm.h>
> +
> +#include <linux/i2c/i2c-hid.h>
> +
> +#include <linux/hid.h>
> +#include <linux/hiddev.h>
> +#include <linux/hidraw.h>
> +
> +#define DRIVER_NAME            "i2chid"
> +#define DRIVER_DESC            "HID over I2C core driver"
> +
> +#define I2C_HID_COMMAND_TRIES  3
> +
> +/* flags */
> +#define I2C_HID_STARTED                (1 << 0)
> +#define I2C_HID_OUT_RUNNING    (1 << 1)
> +#define I2C_HID_IN_RUNNING     (1 << 2)
> +#define I2C_HID_RESET_PENDING  (1 << 3)
> +#define I2C_HID_SUSPENDED      (1 << 4)
> +
> +#define I2C_HID_PWR_ON         0x00
> +#define I2C_HID_PWR_SLEEP      0x01
> +
> +/* debug option */
> +static bool debug = false;
> +module_param(debug, bool, 0444);
> +MODULE_PARM_DESC(debug, "print a lot of debug informations");
> +
> +struct i2chid_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;
> +} __packed;
> +
> +struct i2chid_cmd {
> +       enum {
> +               /* fecth HID descriptor */
> +               HID_DESCR_CMD,
> +
> +               /* fetch report descriptors */
> +               HID_REPORT_DESCR_CMD,
> +
> +               /* commands */
> +               HID_RESET_CMD,
> +               HID_GET_REPORT_CMD,
> +               HID_SET_REPORT_CMD,
> +               HID_GET_IDLE_CMD,
> +               HID_SET_IDLE_CMD,
> +               HID_GET_PROTOCOL_CMD,
> +               HID_SET_PROTOCOL_CMD,
> +               HID_SET_POWER_CMD,
> +
> +               /* read/write data register */
> +               HID_DATA_CMD,
> +       } name;
> +       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(name_, opcode_) \
> +       .name = name_, .opcode = opcode_, .length = 4, \
> +       .registerIndex = offsetof(struct i2chid_desc, wCommandRegister)
> +
> +static const struct i2chid_cmd cmds[] = {
> +       { I2C_HID_CMD(HID_RESET_CMD,            0x01), .wait = true },
> +       { I2C_HID_CMD(HID_GET_REPORT_CMD,       0x02) },
> +       { I2C_HID_CMD(HID_SET_REPORT_CMD,       0x03) },
> +       { I2C_HID_CMD(HID_GET_IDLE_CMD,         0x04) },
> +       { I2C_HID_CMD(HID_SET_IDLE_CMD,         0x05) },
> +       { I2C_HID_CMD(HID_GET_PROTOCOL_CMD,     0x06) },
> +       { I2C_HID_CMD(HID_SET_PROTOCOL_CMD,     0x07) },
> +       { I2C_HID_CMD(HID_SET_POWER_CMD,        0x08) },
> +
> +       {.name = HID_DESCR_CMD,
> +        .length = 2},
> +
> +       {.name = HID_REPORT_DESCR_CMD,
> +        .registerIndex = offsetof(struct i2chid_desc, wReportDescRegister),
> +        .opcode = 0x00,
> +        .length = 2},
> +
> +       {.name = HID_DATA_CMD,
> +        .registerIndex = offsetof(struct i2chid_desc, wDataRegister),
> +        .opcode = 0x00,
> +        .length = 2},
> +
> +       {}, /* terminating */
> +};
> +
> +/* The main device structure */
> +struct i2chid {
> +       struct i2c_client       *client;        /* i2c client */
> +       struct hid_device       *hid;   /* pointer to corresponding HID dev */
> +       union {
> +               __u8 hdesc_buffer[sizeof(struct i2chid_desc)];
> +               struct i2chid_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 */
> +
> +       spinlock_t              flock;          /* flags spinlock */
> +       unsigned long           flags;          /* device flags */
> +
> +       int                     irq;            /* the interrupt line irq */
> +
> +       wait_queue_head_t       wait;           /* For waiting the interrupt */
> +};
> +
> +void i2chid_print_buffer(struct i2chid *ihid, u8 *buf, unsigned int n)
> +{
> +       int i;
> +       char *string = kzalloc((n*3+1)*sizeof(char), GFP_KERNEL);
> +       char tmpbuf[4] = "";
> +
> +       for (i = 0; i < n; ++i) {
> +               sprintf(tmpbuf, "%02x ", buf[i] & 0xFF);
> +               strcat(string, tmpbuf);
> +       }
> +
> +       dev_err(&ihid->client->dev, "%s\n", string);
> +       kfree(string);
> +}
> +
> +static int __i2chid_command(struct i2c_client *client, int command, u8 reportID,
> +               u8 reportType, u8 *args, int args_len,
> +               unsigned char *buf_recv, int data_len)
> +{
> +       struct i2chid *ihid = i2c_get_clientdata(client);
> +       union command *cmd;
> +       unsigned char *rec_buf = buf_recv;
> +       int ret;
> +       int tries = I2C_HID_COMMAND_TRIES;
> +       int length = 0;
> +       struct i2c_msg msg[2];
> +       int msg_num = 0;
> +       int i;
> +       bool wait = false;
> +
> +       if (WARN_ON(!ihid))
> +               return -ENODEV;
> +
> +       cmd = kmalloc(args_len + sizeof(union command), GFP_KERNEL);
> +       if (!cmd)
> +               return -ENOMEM;
> +
> +       for (i = 0; cmds[i].length; i++) {
> +               unsigned int registerIndex;
> +
> +               if (cmds[i].name != command)
> +                       continue;
> +
> +               registerIndex = cmds[i].registerIndex;
> +               cmd->data[0] = ihid->hdesc_buffer[registerIndex];
> +               cmd->data[1] = ihid->hdesc_buffer[registerIndex + 1];
> +               cmd->c.opcode = cmds[i].opcode;
> +               length = cmds[i].length;
> +               wait = cmds[i].wait;
> +       }
> +
> +       /* special case for HID_DESCR_CMD */
> +       if (command == HID_DESCR_CMD)
> +               cmd->c.reg = ihid->wHIDDescRegister;
> +
> +       cmd->c.reportTypeID = reportID | reportType << 4;
> +
> +       memcpy(cmd->data + length, args, args_len);
> +       length += args_len;
> +
> +       if (debug) {
> +               char tmpstr[4] = "";
> +               char strbuf[50] = "";
> +               int i;
> +               for (i = 0; i < length; i++) {
> +                       sprintf(tmpstr, "%02x ", cmd->data[i] & 0xFF);
> +                       strcat(strbuf, tmpstr);
> +               }
> +               dev_err(&client->dev, "%s, cmd=%s\n", __func__, strbuf);
> +       }
> +
> +       msg[0].addr = client->addr;
> +       msg[0].flags = client->flags & I2C_M_TEN;
> +       msg[0].len = length;
> +       msg[0].buf = (char *) cmd->data;
> +       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 = rec_buf;
> +
> +       msg_num = data_len > 0 ? 2 : 1;
> +
> +       if (wait) {
> +               spin_lock_irq(&ihid->flock);
> +               set_bit(I2C_HID_RESET_PENDING, &ihid->flags);
> +               spin_unlock_irq(&ihid->flock);
> +       }
> +
> +       do {
> +               ret = i2c_transfer(client->adapter, msg, msg_num);
> +               if (ret > 0)
> +                       break;
> +               tries--;
> +               dev_dbg(&client->dev, "retrying i2chid_command:%d (%d)\n",
> +                       command, tries);
> +       } while (tries > 0);
> +
> +       if (wait && ret > 0) {
> +               if (debug)
> +                       dev_err(&client->dev, "%s: waiting....\n", __func__);
> +               if (!wait_event_timeout(ihid->wait,
> +                               !test_bit(I2C_HID_RESET_PENDING, &ihid->flags),
> +                               msecs_to_jiffies(5000)))
> +                       ret = -ENODATA;
> +               if (debug)
> +                       dev_err(&client->dev, "%s: finished.\n", __func__);
> +       }
> +
> +       kfree(cmd);
> +
> +       return ret > 0 ? ret != msg_num : ret;
> +}
> +
> +static int i2chid_command(struct i2c_client *client, int command,
> +               unsigned char *buf_recv, int data_len)
> +{
> +       return __i2chid_command(client, command, 0, 0, NULL, 0,
> +                               buf_recv, data_len);
> +}
> +
> +static int i2chid_get_report(struct i2c_client *client, u8 reportType,
> +               u32 reportID, unsigned char *buf_recv, int data_len)
> +{
> +       struct i2chid *ihid = i2c_get_clientdata(client);
> +       u8 args[6];
> +       int ret;
> +       int args_len = 0;
> +       u16 readRegister = ihid->hdesc.wDataRegister;
> +
> +       if (debug)
> +               dev_err(&client->dev, "%s\n", __func__);
> +
> +       if (reportID >= 15) {
> +               args[args_len++] = (reportID >> 0) & 0xFF;
> +               args[args_len++] = (reportID >> 8) & 0xFF;
> +               args[args_len++] = (reportID >> 16) & 0xFF;
> +               args[args_len++] = (reportID >> 24) & 0xFF;
> +               reportID = 0x0F;
> +       }
> +
> +       args[args_len++] = readRegister & 0xff;
> +       args[args_len++] = (readRegister >> 8) & 0xff;
> +
> +       ret = __i2chid_command(client, HID_GET_REPORT_CMD, reportID & 0x0F,
> +               reportType, args, args_len, buf_recv, data_len);
> +       if (ret) {
> +               dev_err(&client->dev, "HID_GET_REPORT_CMD Fail\n");
> +               return -EINVAL;
> +       }
> +
> +       return 0;
> +}
> +
> +static int i2chid_set_report(struct i2c_client *client, u8 reportType,
> +               u32 reportID, unsigned char *buf, int data_len)
> +{
> +       struct i2chid *ihid = i2c_get_clientdata(client);
> +       u8 *args;
> +       int ret;
> +       u16 dataRegister = ihid->hdesc.wDataRegister;
> +       int args_len =  (reportID >= 15 ? 4 : 0) +
> +                       2 /* dataRegister */ +
> +                       2 /* size */ +
> +                       data_len;
> +       int index = 0;
> +
> +       if (debug)
> +               dev_err(&client->dev, "%s\n", __func__);
> +
> +       args = kmalloc(args_len, GFP_KERNEL);
> +
> +       if (reportID >= 15) {
> +               args[index++] = (reportID >> 0) & 0xFF;
> +               args[index++] = (reportID >> 8) & 0xFF;
> +               args[index++] = (reportID >> 16) & 0xFF;
> +               args[index++] = (reportID >> 24) & 0xFF;
> +               reportID = 0x0F;
> +       }
> +
> +       args[index++] = dataRegister & 0xff;
> +       args[index++] = (dataRegister >> 8) & 0xff;
> +
> +       args[index++] = data_len & 0xff;
> +       args[index++] = (data_len >> 8) & 0xff;
> +
> +       memcpy(&args[index], buf, data_len);
> +
> +       ret = __i2chid_command(client, HID_SET_REPORT_CMD, reportID & 0x0F,
> +               reportType, args, args_len, NULL, 0);
> +       if (ret) {
> +               dev_err(&client->dev, "HID_SET_REPORT_CMD Fail\n");
> +               return -EINVAL;
> +       }
> +
> +       kfree(args);
> +       return data_len;
> +}
> +
> +static int i2chid_set_power(struct i2c_client *client, int power_state)
> +{
> +       int ret;
> +
> +       if (debug)
> +               dev_err(&client->dev, "%s\n", __func__);
> +
> +       ret = __i2chid_command(client, HID_SET_POWER_CMD, power_state & 0x01,
> +               0, NULL, 0, NULL, 0);
> +       if (ret) {
> +               dev_err(&client->dev, "HID_SET_POWER_CMD Fail\n");
> +               return -EINVAL;
may be errors can be passed on.

> +       }
> +
> +       return 0;
> +}
> +
> +static int i2chid_hwreset(struct i2c_client *client)
> +{
> +       uint8_t buf_recv[79];
> +       int ret;
> +
> +       if (debug)
> +               dev_err(&client->dev, "%s\n", __func__);
> +
> +       ret = i2chid_set_power(client, I2C_HID_PWR_ON);
> +       if (ret)
> +               return -EINVAL;
why not just pass on the error?

> +
> +       if (debug)
> +               dev_err(&client->dev, "resetting...\n");
this is a little uncustomary.

May be consider  bdg
> +
> +       ret = i2chid_command(client, HID_RESET_CMD, buf_recv, 0);
> +       if (ret) {
> +               dev_err(&client->dev, "HID_RESET_CMD Fail\n");
> +               return -EINVAL;
> +       }
> +
> +       ret = i2c_master_recv(client, buf_recv, 2);
> +       if (ret != 2 || (buf_recv[0] != 0 && buf_recv[1] != 0)) {
> +               dev_err(&client->dev,
> +                       "HID_RESET_CMD Failed: got %02x %02x, size=%d\n",
> +                       buf_recv[0], buf_recv[1], ret);
> +
> +               i2chid_set_power(client, I2C_HID_PWR_SLEEP);
> +               return -EINVAL;
> +       }
> +       return 0;
> +}
> +
> +static bool i2chid_get_input(struct i2chid *ihid)
> +{
> +       int ret;
> +       int size = ihid->hdesc.wMaxInputLength;
> +
> +       ret = i2c_master_recv(ihid->client, ihid->inbuf, size);
> +       if (ret != size) {
> +               dev_err(&ihid->client->dev, "%s: got %d data instead of %d\n",
> +                       __func__, ret, size);
> +               return false;
> +       }
> +
> +       if (debug)
> +               i2chid_print_buffer(ihid, ihid->inbuf, size);
> +
> +       ret = hid_input_report(ihid->hid, HID_INPUT_REPORT, ihid->inbuf + 2,
> +                       size - 2, 1);
> +       if (ret)
> +               return false;
> +
> +       return true;
> +}
> +
> +static irqreturn_t i2chid_irq(int irq, void *dev_id)
> +{
> +       struct i2chid *ihid = dev_id;
> +       int ready;
> +
> +       if (!ihid)
> +               return IRQ_HANDLED;
> +
> +       spin_lock_irq(&ihid->flock);
> +       if (test_and_clear_bit(I2C_HID_RESET_PENDING, &ihid->flags)) {
> +               spin_unlock_irq(&ihid->flock);
> +
> +               wake_up(&ihid->wait);
> +               return IRQ_HANDLED;
> +       }
> +
> +       ready = test_bit(I2C_HID_STARTED, &ihid->flags);
> +       spin_unlock_irq(&ihid->flock);
> +
> +       if (ready)
> +               i2chid_get_input(ihid);
> +
> +       return IRQ_HANDLED;
> +}
> +
> +static int i2chid_get_report_length(struct hid_report *report)
> +{
> +       return ((report->size - 1) >> 3) + 1 +
> +               report->device->report_enum[report->type].numbered + 2;
> +}
> +
> +void i2chid_init_report(struct hid_report *report)
> +{
> +       struct hid_device *hid = report->device;
> +       struct i2c_client *client = hid->driver_data;
> +       struct i2chid *ihid = i2c_get_clientdata(client);
> +       unsigned int size, ret_size;
> +
> +       size = i2chid_get_report_length(report);
> +       i2chid_get_report(client,
> +                       report->type == HID_FEATURE_REPORT ? 0x03 : 0x01,
> +                       report->id, ihid->inbuf, size);
> +
> +       if (debug)
> +               i2chid_print_buffer(ihid, ihid->inbuf, size);
> +
> +       ret_size = ihid->inbuf[0] | (ihid->inbuf[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, ihid->inbuf + 2, size - 2, 1);
> +}
> +
> +/*
> + * Initialize all reports
> + */
> +void i2chid_init_reports(struct hid_device *hid)
> +{
> +       struct hid_report *report;
> +
> +       list_for_each_entry(report,
> +               &hid->report_enum[HID_INPUT_REPORT].report_list, list)
> +               i2chid_init_report(report);
> +
> +       list_for_each_entry(report,
> +               &hid->report_enum[HID_FEATURE_REPORT].report_list, list)
> +               i2chid_init_report(report);
> +}
> +
> +/*
> + * Traverse the supplied list of reports and find the longest
> + */
> +static void i2chid_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 = i2chid_get_report_length(report);
> +               if (*max < size)
> +                       *max = size;
> +       }
> +}
> +
> +static int i2chid_alloc_buffers(struct i2chid *ihid)
> +{
> +       ihid->inbuf = kzalloc(ihid->bufsize, GFP_KERNEL);
> +
> +       if (!ihid->inbuf)
> +               return -1;
> +
> +       return 0;
> +}
> +
> +static void i2chid_free_buffers(struct i2chid *ihid)
> +{
> +       kfree(ihid->inbuf);
> +}
> +
> +static int i2chid_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 i2chid *ihid = i2c_get_clientdata(client);
> +       int ret;
> +
> +       if (count > ihid->bufsize)
> +               count = ihid->bufsize;
> +
> +       ret = i2chid_get_report(client,
> +                       report_type == HID_FEATURE_REPORT ? 0x03 : 0x01,
> +                       report_number, ihid->inbuf, count);
> +
> +       if (ret < 0)
> +               return ret;
> +
> +       count = ihid->inbuf[0] | (ihid->inbuf[1] << 8);
> +
> +       memcpy(buf, ihid->inbuf + 2, count);
> +
> +       return count;
> +}
> +
> +static int i2chid_output_raw_report(struct hid_device *hid, __u8 *buf,
> +               size_t count, unsigned char report_type)
> +{
> +       struct i2c_client *client = hid->driver_data;
> +       int ret;
> +       int report_id = buf[0];
> +
> +       ret = i2chid_set_report(client,
> +                               report_type == HID_FEATURE_REPORT ? 0x03 : 0x01,
> +                               report_id, buf, count);
> +
> +       return ret;
> +
> +}
> +
> +static int i2chid_fetch_hid_descriptor(struct i2chid *ihid)
> +{
> +       struct i2c_client *client = ihid->client;
> +       struct i2chid_desc *hdesc = &ihid->hdesc;
> +       unsigned int dsize = 0;
> +       int ret;
> +
> +       /* Fetch the length of HID description, retrieve the 4 first bytes:
> +        * bytes 0-1 -> length
> +        * bytes 2-3 -> bcdVersion (has to be 1.00) */
> +       ret = i2chid_command(client, HID_DESCR_CMD, ihid->hdesc_buffer, 4);
> +
> +       if (debug)
> +               dev_err(&client->dev,
> +                       "%s, ihid->hdesc_buffer: %02x %02x %02x %02x\n",
> +                       __func__,
> +                       ihid->hdesc_buffer[0],
> +                       ihid->hdesc_buffer[1],
> +                       ihid->hdesc_buffer[2],
> +                       ihid->hdesc_buffer[3]);
> +
> +       if (ret) {
> +               dev_err(&client->dev, "HID_DESCR_LENGTH_CMD Fail (ret=%d)\n",
> +                       ret);
> +               return -EINVAL;
> +       }
> +
> +       dsize = le16_to_cpu(hdesc->wHIDDescLength);
> +       if (!dsize || dsize > HID_MAX_DESCRIPTOR_SIZE) {
> +               dev_err(&client->dev, "weird size of HID descriptor (%u)\n",
> +                       dsize);
> +               return -EINVAL;
> +       }
> +
> +       /* check bcdVersion == 1.0 */
> +       if (le16_to_cpu(hdesc->bcdVersion) != 0x0100) {
> +               dev_err(&client->dev,
> +                       "unexpected HID descriptor bcdVersion (0x%04x)\n",
> +                       le16_to_cpu(hdesc->bcdVersion));
> +               return -EINVAL;
> +       }
> +
> +       if (debug)
> +               dev_err(&client->dev, "Fetching the HID descriptor\n");
> +
> +       ret = i2chid_command(client, HID_DESCR_CMD, ihid->hdesc_buffer, dsize);
> +       if (ret) {
> +               dev_err(&client->dev, "HID_DESCR_CMD Fail\n");
> +               return -EINVAL;
> +       }
> +
> +       if (debug)
> +               i2chid_print_buffer(ihid, ihid->hdesc_buffer, dsize);
> +
> +       return 0;
> +}
> +
> +static int i2chid_parse(struct hid_device *hid)
> +{
> +       struct i2c_client *client = hid->driver_data;
> +       struct i2chid *ihid = i2c_get_clientdata(client);
> +       struct i2chid_desc *hdesc = &ihid->hdesc;
> +       unsigned int rsize = 0;
> +       char *rdesc;
> +       int ret;
> +       int tries = 3;
> +
> +       if (debug)
> +               dev_err(&client->dev, "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 = i2chid_hwreset(client);
> +               if (ret)
> +                       msleep(1000);
> +       } while (tries-- > 0 && ret);
> +
> +       if (ret)
> +               return ret;
> +
> +       rdesc = kmalloc(rsize, GFP_KERNEL);
> +
> +       if (!rdesc) {
> +               dbg_hid("couldn't allocate rdesc memory\n");
> +               return -ENOMEM;
> +       }
> +
> +       if (debug)
> +               dev_err(&client->dev, "asking HID report descriptor\n");
> +
> +       ret = i2chid_command(client, HID_REPORT_DESCR_CMD, rdesc, rsize);
> +       if (ret) {
> +               hid_err(hid, "reading report descriptor failed\n");
> +               kfree(rdesc);
> +               ret = -ENOMEM;
> +               goto err;
> +       }
> +
> +       if (debug)
> +               i2chid_print_buffer(ihid, rdesc, rsize);
> +
> +       ret = hid_parse_report(hid, rdesc, rsize);
> +       kfree(rdesc);
> +       if (ret) {
> +               dbg_hid("parsing report descriptor failed\n");
> +               goto err;
> +       }
> +
> +       return 0;
> +err:
> +       return ret;
> +}
> +
> +static int i2chid_start(struct hid_device *hid)
> +{
> +       struct i2c_client *client = hid->driver_data;
> +       struct i2chid *ihid = i2c_get_clientdata(client);
> +       int ret;
> +
> +       ihid->bufsize = HID_MIN_BUFFER_SIZE;
> +       i2chid_find_max_report(hid, HID_INPUT_REPORT, &ihid->bufsize);
> +       i2chid_find_max_report(hid, HID_OUTPUT_REPORT, &ihid->bufsize);
> +       i2chid_find_max_report(hid, HID_FEATURE_REPORT, &ihid->bufsize);
> +
> +       if (ihid->bufsize > HID_MAX_BUFFER_SIZE)
> +               ihid->bufsize = HID_MAX_BUFFER_SIZE;
> +
> +       if (i2chid_alloc_buffers(ihid)) {
> +               ret = -ENOMEM;
> +               goto fail;
> +       }
> +
> +       if (!(hid->quirks & HID_QUIRK_NO_INIT_REPORTS))
> +               i2chid_init_reports(hid);
> +
> +       return 0;
> +
> +fail:
> +       i2chid_free_buffers(ihid);
> +       return ret;
> +}
> +
> +static void i2chid_stop(struct hid_device *hid)
> +{
> +       struct i2c_client *client = hid->driver_data;
> +       struct i2chid *ihid = i2c_get_clientdata(client);
> +
> +       if (WARN_ON(!ihid))
> +               return;
> +
> +       hid->claimed = 0;
> +
> +       i2chid_free_buffers(ihid);
> +}
> +
> +static int i2chid_open(struct hid_device *hid)
> +{
> +       struct i2c_client *client = hid->driver_data;
> +       struct i2chid *ihid = i2c_get_clientdata(client);
> +       int ret;
> +
> +       if (!hid->open++) {
> +               ret = i2chid_set_power(client, I2C_HID_PWR_ON);
> +               if (ret) {
> +                       hid->open--;
> +                       return -EIO;
> +               }
> +               spin_lock_irq(&ihid->flock);
> +               set_bit(I2C_HID_STARTED, &ihid->flags);
> +               spin_unlock_irq(&ihid->flock);
> +       }
> +       return 0;
> +}
> +
> +static void i2chid_close(struct hid_device *hid)
> +{
> +       struct i2c_client *client = hid->driver_data;
> +       struct i2chid *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
> +        */
> +       if (!--hid->open) {
> +               spin_lock_irq(&ihid->flock);
> +               clear_bit(I2C_HID_STARTED, &ihid->flags);
> +               spin_unlock_irq(&ihid->flock);
> +
> +               /* Save some power */
> +               i2chid_set_power(client, I2C_HID_PWR_SLEEP);
> +       }
> +}
> +
> +static int i2chid_power(struct hid_device *hid, int lvl)
> +{
> +       struct i2c_client *client = hid->driver_data;
> +       int r = 0;
> +
> +       if (debug)
> +               dev_err(&client->dev, "%s lvl:%d\n", __func__, lvl);
> +
> +       switch (lvl) {
> +       case PM_HINT_FULLON:
> +               r = i2chid_set_power(client, I2C_HID_PWR_ON);
> +               break;
> +       case PM_HINT_NORMAL:
> +               r = i2chid_set_power(client, I2C_HID_PWR_SLEEP);
> +               break;
> +       }
> +       return r;
> +}
> +
> +static int i2chid_hidinput_input_event(struct input_dev *dev, unsigned int type,
> +               unsigned int code, int value)
> +{
> +       struct hid_device *hid = input_get_drvdata(dev);
> +       struct hid_field *field;
> +       int offset;
> +
> +       if (type == EV_FF)
> +               return input_ff_event(dev, type, code, value);
> +
> +       if (type != EV_LED)
> +               return -1;
> +
> +       offset = hidinput_find_field(hid, type, code, &field);
> +
> +       if (offset == -1) {
> +               hid_warn(dev, "event field not found\n");
> +               return -1;
> +       }
> +
> +       hid_set_field(field, offset, value);
> +
> +       return 0;
> +}
> +
> +static struct hid_ll_driver i2c_hid_driver = {
> +       .parse = i2chid_parse,
> +       .start = i2chid_start,
> +       .stop = i2chid_stop,
> +       .open = i2chid_open,
> +       .close = i2chid_close,
> +       .power = i2chid_power,
> +       .hidinput_input_event = i2chid_hidinput_input_event,
> +};
> +
> +static int i2chid_init_irq(struct i2c_client *client)
> +{
> +       struct i2chid *ihid = i2c_get_clientdata(client);
> +       int rc;
> +
> +       dev_dbg(&client->dev, "Requesting IRQ: %d\n",
> +               client->irq);
> +
> +       rc = request_threaded_irq(client->irq, NULL, i2chid_irq,
> +                       IRQF_TRIGGER_FALLING | IRQF_ONESHOT,
> +                       DRIVER_NAME, ihid);
> +       if (rc < 0) {
> +               dev_dbg(&client->dev,
> +                       "Could not register for %s interrupt, irq = %d,"
> +                       " rc = %d\n",
> +               DRIVER_NAME, client->irq, rc);
> +
> +               return rc;
> +       }
> +
> +       return client->irq;
> +}
> +
> +static int __devinit i2chid_probe(struct i2c_client *client,
> +               const struct i2c_device_id *dev_id)
> +{
> +       int ret;
> +       struct i2chid *ihid;
> +       struct hid_device *hid;
> +       __u16 hidRegister;
> +       unsigned char tmpstr[11];
> +       struct i2chid_platform_data *platform_data = client->dev.platform_data;
> +
> +       dbg_hid("HID probe called for i2c %d\n", client->addr);
> +
> +       if (!platform_data) {
> +               dev_err(&client->dev, "HID register address not provided\n");
> +               return -EINVAL;
> +       }
> +
> +       if (client->irq < 1) {
> +               dev_err(&client->dev,
> +                       "HID over i2c has not been provided an Int IRQ\n");
> +               return -EINVAL;
> +       }
> +
> +       ihid = kzalloc(sizeof(struct i2chid), GFP_KERNEL);
> +       if (!ihid)
> +               return -ENOMEM;

you may consider devm_* function here.

> +
> +       i2c_set_clientdata(client, ihid);
> +
> +       ihid->client = client;
> +       ihid->flags = 0;
> +
> +       hidRegister = platform_data->hid_descriptor_address;
> +       ihid->wHIDDescRegister = cpu_to_le16(hidRegister);
> +
> +       init_waitqueue_head(&ihid->wait);
> +       spin_lock_init(&ihid->flock);
> +
> +       ret = i2chid_fetch_hid_descriptor(ihid);
> +       if (ret < 0)
> +               goto err;
> +
> +       ihid->irq = i2chid_init_irq(client);
> +       if (ihid->irq < 0)
> +               goto err;
> +
> +       hid = hid_allocate_device();
> +       if (IS_ERR(hid)) {
> +               ret = -ENOMEM;
> +               goto err;
> +       }
> +
> +       ihid->hid = hid;
> +
> +       hid->driver_data = client;
> +       hid->ll_driver = &i2c_hid_driver;
> +       hid->hid_get_raw_report = i2chid_get_raw_report;
> +       hid->hid_output_raw_report = i2chid_output_raw_report;
> +       hid->ff_init = hid_pidff_init;
> +#ifdef CONFIG_USB_HIDDEV
> +       hid->hiddev_connect = hiddev_connect;
> +       hid->hiddev_disconnect = hiddev_disconnect;
> +       hid->hiddev_hid_event = hiddev_hid_event;
> +       hid->hiddev_report_event = hiddev_report_event;
> +#endif
> +       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(tmpstr, sizeof(tmpstr), " %04X:%04X",
> +                hid->vendor, hid->product);
> +       strlcpy(hid->name, client->name, sizeof(hid->name));
> +       strlcat(hid->name, tmpstr, sizeof(hid->name));
> +
> +       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;
> +       }
> +
> +       return 0;
> +
> +err_mem_free:
> +       hid_destroy_device(hid);
> +
> +err:
> +       if (ihid->irq >= 0)
> +               free_irq(ihid->irq, ihid);
> +
> +       kfree(ihid);
> +       return ret;
> +}
> +
> +static int __devexit i2chid_remove(struct i2c_client *client)
> +{
> +       struct i2chid *ihid = i2c_get_clientdata(client);
> +       struct hid_device *hid;
> +
> +       if (WARN_ON(!ihid))
> +               return -1;
> +
> +       hid = ihid->hid;
> +       hid_destroy_device(hid);
> +
> +       free_irq(client->irq, ihid);
> +
> +       kfree(ihid);
> +
> +       return 0;
> +}
> +
> +#ifdef CONFIG_PM_SLEEP
> +static int i2chid_suspend(struct device *dev)
> +{
> +       struct i2c_client *client = to_i2c_client(dev);
> +       struct i2chid *ihid = i2c_get_clientdata(client);
> +
> +       if (device_may_wakeup(&client->dev))
> +               enable_irq_wake(ihid->irq);
> +
> +       /* Save some power */
> +       i2chid_set_power(client, I2C_HID_PWR_SLEEP);
> +
> +       return 0;
> +}
> +
> +static int i2chid_resume(struct device *dev)
> +{
> +       int ret;
> +       struct i2c_client *client = to_i2c_client(dev);
> +
> +       ret = i2chid_hwreset(client);
> +       if (ret)
> +               return ret;
> +
> +       if (device_may_wakeup(&client->dev))
> +               enable_irq_wake(client->irq);
> +
> +       return 0;
> +}
> +#endif
> +
> +static SIMPLE_DEV_PM_OPS(i2chid_pm, i2chid_suspend, i2chid_resume);
> +
> +static const struct i2c_device_id i2chid_id_table[] = {
> +       { "i2chid", 0 },
> +       { },
> +};
> +MODULE_DEVICE_TABLE(i2c, i2chid_id_table);
> +
> +
> +static struct i2c_driver i2chid_driver = {
> +       .driver = {
> +               .name   = DRIVER_NAME,
> +               .owner  = THIS_MODULE,
> +               .pm     = &i2chid_pm,
> +       },
> +
> +       .probe          = i2chid_probe,
> +       .remove         = __devexit_p(i2chid_remove),
> +
> +       .id_table       = i2chid_id_table,
> +};
> +
> +module_i2c_driver(i2chid_driver);
> +
> +MODULE_DESCRIPTION(DRIVER_DESC);
> +MODULE_AUTHOR("Benjamin Tissoires <benjamin.tissoires@xxxxxxxxx>");
> +MODULE_LICENSE("GPL");
> diff --git a/include/linux/i2c/i2c-hid.h b/include/linux/i2c/i2c-hid.h
> new file mode 100644
> index 0000000..6685605
> --- /dev/null
> +++ b/include/linux/i2c/i2c-hid.h
> @@ -0,0 +1,35 @@
> +/*
> + * HID over I2C protocol implementation
> + *
> + * Copyright (c) 2012 Benjamin Tissoires <benjamin.tissoires@xxxxxxxxx>
> + * Copyright (c) 2012 Ecole Nationale de l'Aviation Civile, France
> + *
> + * 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.
> + */
> +
> +#ifndef __LINUX_I2C_HID_H
> +#define __LINUX_I2C_HID_H
> +
> +#include <linux/types.h>
> +
> +/**
> + * struct i2chid_platform_data - used by hid over i2c implementation.
> + * @hid_descriptor_address: i2c register where the HID descriptor is stored.
> + *
> + * Note that it is the responsibility for the platform driver (or the acpi 5.0
> + * driver) to setup the irq related to the gpio in the struct i2c_board_info.
> + * The platform driver should also setup the gpio according to the device:
> + *
> + * A typical example is the following:
> + *     irq = gpio_to_irq(intr_gpio);
> + *     hkdk4412_i2c_devs5[0].irq = irq; // store the irq in i2c_board_info
> + *     gpio_request(intr_gpio, "elan-irq");
> + *     s3c_gpio_setpull(intr_gpio, S3C_GPIO_PULL_UP);
> + */
> +struct i2chid_platform_data {
> +       u16 hid_descriptor_address;
> +};
> +
> +#endif /* __LINUX_I2C_HID_H */
> --
> 1.7.11.4
>
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