Initial import

1 files changed, 1187 insertions, 0 deletions

diff --git a/drivers/hid/i2c-hid/i2c-hid.c b/drivers/hid/i2c-hid/i2c-hid.c
new file mode 100644
index 000000000..92d6cdf02
--- /dev/null
+++ b/drivers/hid/i2c-hid/i2c-hid.c
@@ -0,0 +1,1187 @@
+/*
+ * 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		(1 << 0)
+#define I2C_HID_RESET_PENDING	(1 << 1)
+#define I2C_HID_READ_PENDING	(1 << 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;
+};
+
+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);
+
+	/* hid_hw_* already checked that data_len < HID_MAX_BUFFER_SIZE */
+	u16 size =	2			/* size */ +
+			(reportID ? 1 : 0)	/* reportID */ +
+			data_len		/* buf */;
+	int args_len =	(reportID >= 0x0F ? 1 : 0) /* optional third byte */ +
+			2			/* dataRegister */ +
+			size			/* args */;
+	int index = 0;
+
+	i2c_hid_dbg(ihid, "%s\n", __func__);
+
+	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__);
+
+	ret = i2c_hid_set_power(client, I2C_HID_PWR_ON);
+	if (ret)
+		return ret;
+
+	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);
+		return ret;
+	}
+
+	return 0;
+}
+
+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;
+	int report_id = buf[0];
+	int ret;
+
+	if (report_type == HID_INPUT_REPORT)
+		return -EINVAL;
+
+	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 */
+
+	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);
+
+	/* 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);
+
+	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;
+	ACPI_COMPANION_SET(&hid->dev, ACPI_COMPANION(&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);
+
+	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;
+}
+
+#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 = 0;
+
+	disable_irq(ihid->irq);
+	if (device_may_wakeup(&client->dev))
+		enable_irq_wake(ihid->irq);
+
+	if (hid->driver && hid->driver->suspend)
+		ret = hid->driver->suspend(hid, PMSG_SUSPEND);
+
+	/* Save some power */
+	i2c_hid_set_power(client, I2C_HID_PWR_SLEEP);
+
+	return ret;
+}
+
+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;
+
+	enable_irq(ihid->irq);
+	ret = i2c_hid_hwreset(client);
+	if (ret)
+		return ret;
+
+	if (device_may_wakeup(&client->dev))
+		disable_irq_wake(ihid->irq);
+
+	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 },
+	{ },
+};
+MODULE_DEVICE_TABLE(i2c, i2c_hid_id_table);
+
+
+static struct i2c_driver i2c_hid_driver = {
+	.driver = {
+		.name	= "i2c_hid",
+		.owner	= THIS_MODULE,
+		.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,
+
+	.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");