Input: add IMS Passenger Control Unit driver

The PCU is a device installed in the armrest of a plane seat and
is connected to IMS Rave Entertainment System. It has a set of control
buttons (Volume Up/Down, Attendant, Lights, etc) on one side and
gamepad-like controls on the other side.

Originally the device was handled from userspace and because of that
it presents itself on USB bus as a CDC-ACM modem device that however
can not make calls. However the custom handling is not as convenient
as using standard input subsystem facilities. If it was pure input
device it would be possible to continue using userspace solution
(moving it over to uinput), but the device also has backlighted keys
which can not be supported via uinput.

Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

3 files changed, 1911 insertions, 0 deletions

diff --git a/drivers/input/misc/Kconfig b/drivers/input/misc/Kconfig
index 2a1647ef561..3ec8887ce45 100644
--- a/drivers/input/misc/Kconfig
+++ b/drivers/input/misc/Kconfig
@@ -580,6 +580,16 @@ config INPUT_ADXL34X_SPI
 	  To compile this driver as a module, choose M here: the
 	  module will be called adxl34x-spi.
 
+config INPUT_IMS_PCU
+	tristate "IMS Passenger Control Unit driver"
+	depends on USB
+	depends on LEDS_CLASS
+	help
+	  Say Y here if you have system with IMS Rave Passenger Control Unit.
+
+	  To compile this driver as a module, choose M here: the module will be
+	  called ims_pcu.
+
 config INPUT_CMA3000
 	tristate "VTI CMA3000 Tri-axis accelerometer"
 	help
diff --git a/drivers/input/misc/Makefile b/drivers/input/misc/Makefile
index 1f874afeea6..d6873433ba7 100644
--- a/drivers/input/misc/Makefile
+++ b/drivers/input/misc/Makefile
@@ -28,6 +28,7 @@ obj-$(CONFIG_INPUT_DM355EVM)		+= dm355evm_keys.o
 obj-$(CONFIG_INPUT_GP2A)		+= gp2ap002a00f.o
 obj-$(CONFIG_INPUT_GPIO_TILT_POLLED)	+= gpio_tilt_polled.o
 obj-$(CONFIG_HP_SDC_RTC)		+= hp_sdc_rtc.o
+obj-$(CONFIG_INPUT_IMS_PCU)		+= ims-pcu.o
 obj-$(CONFIG_INPUT_IXP4XX_BEEPER)	+= ixp4xx-beeper.o
 obj-$(CONFIG_INPUT_KEYSPAN_REMOTE)	+= keyspan_remote.o
 obj-$(CONFIG_INPUT_KXTJ9)		+= kxtj9.o
diff --git a/drivers/input/misc/ims-pcu.c b/drivers/input/misc/ims-pcu.c
new file mode 100644
index 00000000000..1b044b99da6
--- /dev/null
+++ b/drivers/input/misc/ims-pcu.c
@@ -0,0 +1,1900 @@
+/*
+ * Driver for IMS Passenger Control Unit Devices
+ *
+ * Copyright (C) 2013 The IMS Company
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2
+ * as published by the Free Software Foundation.
+ */
+
+#include <linux/completion.h>
+#include <linux/device.h>
+#include <linux/firmware.h>
+#include <linux/ihex.h>
+#include <linux/input.h>
+#include <linux/kernel.h>
+#include <linux/leds.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/types.h>
+#include <linux/usb/input.h>
+#include <linux/usb/cdc.h>
+#include <asm/unaligned.h>
+
+#define IMS_PCU_KEYMAP_LEN		32
+
+struct ims_pcu_buttons {
+	struct input_dev *input;
+	char name[32];
+	char phys[32];
+	unsigned short keymap[IMS_PCU_KEYMAP_LEN];
+};
+
+struct ims_pcu_gamepad {
+	struct input_dev *input;
+	char name[32];
+	char phys[32];
+};
+
+struct ims_pcu_backlight {
+	struct led_classdev cdev;
+	struct work_struct work;
+	enum led_brightness desired_brightness;
+	char name[32];
+};
+
+#define IMS_PCU_PART_NUMBER_LEN		15
+#define IMS_PCU_SERIAL_NUMBER_LEN	8
+#define IMS_PCU_DOM_LEN			8
+#define IMS_PCU_FW_VERSION_LEN		(9 + 1)
+#define IMS_PCU_BL_VERSION_LEN		(9 + 1)
+#define IMS_PCU_BL_RESET_REASON_LEN	(2 + 1)
+
+#define IMS_PCU_BUF_SIZE		128
+
+struct ims_pcu {
+	struct usb_device *udev;
+	struct device *dev; /* control interface's device, used for logging */
+
+	unsigned int device_no;
+
+	bool bootloader_mode;
+
+	char part_number[IMS_PCU_PART_NUMBER_LEN];
+	char serial_number[IMS_PCU_SERIAL_NUMBER_LEN];
+	char date_of_manufacturing[IMS_PCU_DOM_LEN];
+	char fw_version[IMS_PCU_FW_VERSION_LEN];
+	char bl_version[IMS_PCU_BL_VERSION_LEN];
+	char reset_reason[IMS_PCU_BL_RESET_REASON_LEN];
+	int update_firmware_status;
+
+	struct usb_interface *ctrl_intf;
+
+	struct usb_endpoint_descriptor *ep_ctrl;
+	struct urb *urb_ctrl;
+	u8 *urb_ctrl_buf;
+	dma_addr_t ctrl_dma;
+	size_t max_ctrl_size;
+
+	struct usb_interface *data_intf;
+
+	struct usb_endpoint_descriptor *ep_in;
+	struct urb *urb_in;
+	u8 *urb_in_buf;
+	dma_addr_t read_dma;
+	size_t max_in_size;
+
+	struct usb_endpoint_descriptor *ep_out;
+	u8 *urb_out_buf;
+	size_t max_out_size;
+
+	u8 read_buf[IMS_PCU_BUF_SIZE];
+	u8 read_pos;
+	u8 check_sum;
+	bool have_stx;
+	bool have_dle;
+
+	u8 cmd_buf[IMS_PCU_BUF_SIZE];
+	u8 ack_id;
+	u8 expected_response;
+	u8 cmd_buf_len;
+	struct completion cmd_done;
+	struct mutex cmd_mutex;
+
+	u32 fw_start_addr;
+	u32 fw_end_addr;
+	struct completion async_firmware_done;
+
+	struct ims_pcu_buttons buttons;
+	struct ims_pcu_gamepad *gamepad;
+	struct ims_pcu_backlight backlight;
+
+	bool setup_complete; /* Input and LED devices have been created */
+};
+
+
+/*********************************************************************
+ *             Buttons Input device support                          *
+ *********************************************************************/
+
+static const unsigned short ims_pcu_keymap_1[] = {
+	[1] = KEY_ATTENDANT_OFF,
+	[2] = KEY_ATTENDANT_ON,
+	[3] = KEY_LIGHTS_TOGGLE,
+	[4] = KEY_VOLUMEUP,
+	[5] = KEY_VOLUMEDOWN,
+	[6] = KEY_INFO,
+};
+
+static const unsigned short ims_pcu_keymap_2[] = {
+	[4] = KEY_VOLUMEUP,
+	[5] = KEY_VOLUMEDOWN,
+	[6] = KEY_INFO,
+};
+
+static const unsigned short ims_pcu_keymap_3[] = {
+	[1] = KEY_HOMEPAGE,
+	[2] = KEY_ATTENDANT_TOGGLE,
+	[3] = KEY_LIGHTS_TOGGLE,
+	[4] = KEY_VOLUMEUP,
+	[5] = KEY_VOLUMEDOWN,
+	[6] = KEY_DISPLAYTOGGLE,
+	[18] = KEY_PLAYPAUSE,
+};
+
+static const unsigned short ims_pcu_keymap_4[] = {
+	[1] = KEY_ATTENDANT_OFF,
+	[2] = KEY_ATTENDANT_ON,
+	[3] = KEY_LIGHTS_TOGGLE,
+	[4] = KEY_VOLUMEUP,
+	[5] = KEY_VOLUMEDOWN,
+	[6] = KEY_INFO,
+	[18] = KEY_PLAYPAUSE,
+};
+
+static const unsigned short ims_pcu_keymap_5[] = {
+	[1] = KEY_ATTENDANT_OFF,
+	[2] = KEY_ATTENDANT_ON,
+	[3] = KEY_LIGHTS_TOGGLE,
+};
+
+struct ims_pcu_device_info {
+	const unsigned short *keymap;
+	size_t keymap_len;
+	bool has_gamepad;
+};
+
+#define IMS_PCU_DEVINFO(_n, _gamepad)				\
+	[_n] = {						\
+		.keymap = ims_pcu_keymap_##_n,			\
+		.keymap_len = ARRAY_SIZE(ims_pcu_keymap_##_n),	\
+		.has_gamepad = _gamepad,			\
+	}
+
+static const struct ims_pcu_device_info ims_pcu_device_info[] = {
+	IMS_PCU_DEVINFO(1, true),
+	IMS_PCU_DEVINFO(2, true),
+	IMS_PCU_DEVINFO(3, true),
+	IMS_PCU_DEVINFO(4, true),
+	IMS_PCU_DEVINFO(5, false),
+};
+
+static void ims_pcu_buttons_report(struct ims_pcu *pcu, u32 data)
+{
+	struct ims_pcu_buttons *buttons = &pcu->buttons;
+	struct input_dev *input = buttons->input;
+	int i;
+
+	for (i = 0; i < 32; i++) {
+		unsigned short keycode = buttons->keymap[i];
+
+		if (keycode != KEY_RESERVED)
+			input_report_key(input, keycode, data & (1UL << i));
+	}
+
+	input_sync(input);
+}
+
+static int ims_pcu_setup_buttons(struct ims_pcu *pcu,
+				 const unsigned short *keymap,
+				 size_t keymap_len)
+{
+	struct ims_pcu_buttons *buttons = &pcu->buttons;
+	struct input_dev *input;
+	int i;
+	int error;
+
+	input = input_allocate_device();
+	if (!input) {
+		dev_err(pcu->dev,
+			"Not enough memory for input input device\n");
+		return -ENOMEM;
+	}
+
+	snprintf(buttons->name, sizeof(buttons->name),
+		 "IMS PCU#%d Button Interface", pcu->device_no);
+
+	usb_make_path(pcu->udev, buttons->phys, sizeof(buttons->phys));
+	strlcat(buttons->phys, "/input0", sizeof(buttons->phys));
+
+	memcpy(buttons->keymap, keymap, sizeof(*keymap) * keymap_len);
+
+	input->name = buttons->name;
+	input->phys = buttons->phys;
+	usb_to_input_id(pcu->udev, &input->id);
+	input->dev.parent = &pcu->ctrl_intf->dev;
+
+	input->keycode = buttons->keymap;
+	input->keycodemax = ARRAY_SIZE(buttons->keymap);
+	input->keycodesize = sizeof(buttons->keymap[0]);
+
+	__set_bit(EV_KEY, input->evbit);
+	for (i = 0; i < IMS_PCU_KEYMAP_LEN; i++)
+		__set_bit(buttons->keymap[i], input->keybit);
+	__clear_bit(KEY_RESERVED, input->keybit);
+
+	error = input_register_device(input);
+	if (error) {
+		dev_err(pcu->dev,
+			"Failed to register buttons input device: %d\n",
+			error);
+		input_free_device(input);
+		return error;
+	}
+
+	buttons->input = input;
+	return 0;
+}
+
+static void ims_pcu_destroy_buttons(struct ims_pcu *pcu)
+{
+	struct ims_pcu_buttons *buttons = &pcu->buttons;
+
+	input_unregister_device(buttons->input);
+}
+
+
+/*********************************************************************
+ *             Gamepad Input device support                          *
+ *********************************************************************/
+
+static void ims_pcu_gamepad_report(struct ims_pcu *pcu, u32 data)
+{
+	struct ims_pcu_gamepad *gamepad = pcu->gamepad;
+	struct input_dev *input = gamepad->input;
+	int x, y;
+
+	x = !!(data & (1 << 14)) - !!(data & (1 << 13));
+	y = !!(data & (1 << 12)) - !!(data & (1 << 11));
+
+	input_report_abs(input, ABS_X, x);
+	input_report_abs(input, ABS_Y, y);
+
+	input_report_key(input, BTN_A, data & (1 << 7));
+	input_report_key(input, BTN_B, data & (1 << 8));
+	input_report_key(input, BTN_X, data & (1 << 9));
+	input_report_key(input, BTN_Y, data & (1 << 10));
+	input_report_key(input, BTN_START, data & (1 << 15));
+	input_report_key(input, BTN_SELECT, data & (1 << 16));
+
+	input_sync(input);
+}
+
+static int ims_pcu_setup_gamepad(struct ims_pcu *pcu)
+{
+	struct ims_pcu_gamepad *gamepad;
+	struct input_dev *input;
+	int error;
+
+	gamepad = kzalloc(sizeof(struct ims_pcu_gamepad), GFP_KERNEL);
+	input = input_allocate_device();
+	if (!gamepad || !input) {
+		dev_err(pcu->dev,
+			"Not enough memory for gamepad device\n");
+		return -ENOMEM;
+	}
+
+	gamepad->input = input;
+
+	snprintf(gamepad->name, sizeof(gamepad->name),
+		 "IMS PCU#%d Gamepad Interface", pcu->device_no);
+
+	usb_make_path(pcu->udev, gamepad->phys, sizeof(gamepad->phys));
+	strlcat(gamepad->phys, "/input1", sizeof(gamepad->phys));
+
+	input->name = gamepad->name;
+	input->phys = gamepad->phys;
+	usb_to_input_id(pcu->udev, &input->id);
+	input->dev.parent = &pcu->ctrl_intf->dev;
+
+	__set_bit(EV_KEY, input->evbit);
+	__set_bit(BTN_A, input->keybit);
+	__set_bit(BTN_B, input->keybit);
+	__set_bit(BTN_X, input->keybit);
+	__set_bit(BTN_Y, input->keybit);
+	__set_bit(BTN_START, input->keybit);
+	__set_bit(BTN_SELECT, input->keybit);
+
+	__set_bit(EV_ABS, input->evbit);
+	input_set_abs_params(input, ABS_X, -1, 1, 0, 0);
+	input_set_abs_params(input, ABS_Y, -1, 1, 0, 0);
+
+	error = input_register_device(input);
+	if (error) {
+		dev_err(pcu->dev,
+			"Failed to register gamepad input device: %d\n",
+			error);
+		goto err_free_mem;
+	}
+
+	pcu->gamepad = gamepad;
+	return 0;
+
+err_free_mem:
+	input_free_device(input);
+	kfree(gamepad);
+	return -ENOMEM;
+}
+
+static void ims_pcu_destroy_gamepad(struct ims_pcu *pcu)
+{
+	struct ims_pcu_gamepad *gamepad = pcu->gamepad;
+
+	input_unregister_device(gamepad->input);
+	kfree(gamepad);
+}
+
+
+/*********************************************************************
+ *             PCU Communication protocol handling                   *
+ *********************************************************************/
+
+#define IMS_PCU_PROTOCOL_STX		0x02
+#define IMS_PCU_PROTOCOL_ETX		0x03
+#define IMS_PCU_PROTOCOL_DLE		0x10
+
+/* PCU commands */
+#define IMS_PCU_CMD_STATUS		0xa0
+#define IMS_PCU_CMD_PCU_RESET		0xa1
+#define IMS_PCU_CMD_RESET_REASON	0xa2
+#define IMS_PCU_CMD_SEND_BUTTONS	0xa3
+#define IMS_PCU_CMD_JUMP_TO_BTLDR	0xa4
+#define IMS_PCU_CMD_GET_INFO		0xa5
+#define IMS_PCU_CMD_SET_BRIGHTNESS	0xa6
+#define IMS_PCU_CMD_EEPROM		0xa7
+#define IMS_PCU_CMD_GET_FW_VERSION	0xa8
+#define IMS_PCU_CMD_GET_BL_VERSION	0xa9
+#define IMS_PCU_CMD_SET_INFO		0xab
+#define IMS_PCU_CMD_GET_BRIGHTNESS	0xac
+#define IMS_PCU_CMD_GET_DEVICE_ID	0xae
+#define IMS_PCU_CMD_SPECIAL_INFO	0xb0
+#define IMS_PCU_CMD_BOOTLOADER		0xb1	/* Pass data to bootloader */
+
+/* PCU responses */
+#define IMS_PCU_RSP_STATUS		0xc0
+#define IMS_PCU_RSP_PCU_RESET		0	/* Originally 0xc1 */
+#define IMS_PCU_RSP_RESET_REASON	0xc2
+#define IMS_PCU_RSP_SEND_BUTTONS	0xc3
+#define IMS_PCU_RSP_JUMP_TO_BTLDR	0	/* Originally 0xc4 */
+#define IMS_PCU_RSP_GET_INFO		0xc5
+#define IMS_PCU_RSP_SET_BRIGHTNESS	0xc6
+#define IMS_PCU_RSP_EEPROM		0xc7
+#define IMS_PCU_RSP_GET_FW_VERSION	0xc8
+#define IMS_PCU_RSP_GET_BL_VERSION	0xc9
+#define IMS_PCU_RSP_SET_INFO		0xcb
+#define IMS_PCU_RSP_GET_BRIGHTNESS	0xcc
+#define IMS_PCU_RSP_CMD_INVALID		0xcd
+#define IMS_PCU_RSP_GET_DEVICE_ID	0xce
+#define IMS_PCU_RSP_SPECIAL_INFO	0xd0
+#define IMS_PCU_RSP_BOOTLOADER		0xd1	/* Bootloader response */
+
+#define IMS_PCU_RSP_EVNT_BUTTONS	0xe0	/* Unsolicited, button state */
+#define IMS_PCU_GAMEPAD_MASK		0x0001ff80UL	/* Bits 7 through 16 */
+
+
+#define IMS_PCU_MIN_PACKET_LEN		3
+#define IMS_PCU_DATA_OFFSET		2
+
+#define IMS_PCU_CMD_WRITE_TIMEOUT	100 /* msec */
+#define IMS_PCU_CMD_RESPONSE_TIMEOUT	500 /* msec */
+
+static void ims_pcu_report_events(struct ims_pcu *pcu)
+{
+	u32 data = get_unaligned_be32(&pcu->read_buf[3]);
+
+	ims_pcu_buttons_report(pcu, data & ~IMS_PCU_GAMEPAD_MASK);
+	if (pcu->gamepad)
+		ims_pcu_gamepad_report(pcu, data);
+}
+
+static void ims_pcu_handle_response(struct ims_pcu *pcu)
+{
+	switch (pcu->read_buf[0]) {
+	case IMS_PCU_RSP_EVNT_BUTTONS:
+		if (likely(pcu->setup_complete))
+			ims_pcu_report_events(pcu);
+		break;
+
+	default:
+		/*
+		 * See if we got command completion.
+		 * If both the sequence and response code match save
+		 * the data and signal completion.
+		 */
+		if (pcu->read_buf[0] == pcu->expected_response &&
+		    pcu->read_buf[1] == pcu->ack_id - 1) {
+
+			memcpy(pcu->cmd_buf, pcu->read_buf, pcu->read_pos);
+			pcu->cmd_buf_len = pcu->read_pos;
+			complete(&pcu->cmd_done);
+		}
+		break;
+	}
+}
+
+static void ims_pcu_process_data(struct ims_pcu *pcu, struct urb *urb)
+{
+	int i;
+
+	for (i = 0; i < urb->actual_length; i++) {
+		u8 data = pcu->urb_in_buf[i];
+
+		/* Skip everything until we get Start Xmit */
+		if (!pcu->have_stx && data != IMS_PCU_PROTOCOL_STX)
+			continue;
+
+		if (pcu->have_dle) {
+			pcu->have_dle = false;
+			pcu->read_buf[pcu->read_pos++] = data;
+			pcu->check_sum += data;
+			continue;
+		}
+
+		switch (data) {
+		case IMS_PCU_PROTOCOL_STX:
+			if (pcu->have_stx)
+				dev_warn(pcu->dev,
+					 "Unexpected STX at byte %d, discarding old data\n",
+					 pcu->read_pos);
+			pcu->have_stx = true;
+			pcu->have_dle = false;
+			pcu->read_pos = 0;
+			pcu->check_sum = 0;
+			break;
+
+		case IMS_PCU_PROTOCOL_DLE:
+			pcu->have_dle = true;
+			break;
+
+		case IMS_PCU_PROTOCOL_ETX:
+			if (pcu->read_pos < IMS_PCU_MIN_PACKET_LEN) {
+				dev_warn(pcu->dev,
+					 "Short packet received (%d bytes), ignoring\n",
+					 pcu->read_pos);
+			} else if (pcu->check_sum != 0) {
+				dev_warn(pcu->dev,
+					 "Invalid checksum in packet (%d bytes), ignoring\n",
+					 pcu->read_pos);
+			} else {
+				ims_pcu_handle_response(pcu);
+			}
+
+			pcu->have_stx = false;
+			pcu->have_dle = false;
+			pcu->read_pos = 0;
+			break;
+
+		default:
+			pcu->read_buf[pcu->read_pos++] = data;
+			pcu->check_sum += data;
+			break;
+		}
+	}
+}
+
+static bool ims_pcu_byte_needs_escape(u8 byte)
+{
+	return byte == IMS_PCU_PROTOCOL_STX ||
+	       byte == IMS_PCU_PROTOCOL_ETX ||
+	       byte == IMS_PCU_PROTOCOL_DLE;
+}
+
+static int ims_pcu_send_cmd_chunk(struct ims_pcu *pcu,
+				  u8 command, int chunk, int len)
+{
+	int error;
+
+	error = usb_bulk_msg(pcu->udev,
+			     usb_sndbulkpipe(pcu->udev,
+					     pcu->ep_out->bEndpointAddress),
+			     pcu->urb_out_buf, len,
+			     NULL, IMS_PCU_CMD_WRITE_TIMEOUT);
+	if (error < 0) {
+		dev_dbg(pcu->dev,
+			"Sending 0x%02x command failed at chunk %d: %d\n",
+			command, chunk, error);
+		return error;
+	}
+
+	return 0;
+}
+
+static int ims_pcu_send_command(struct ims_pcu *pcu,
+				u8 command, const u8 *data, int len)
+{
+	int count = 0;
+	int chunk = 0;
+	int delta;
+	int i;
+	int error;
+	u8 csum = 0;
+	u8 ack_id;
+
+	pcu->urb_out_buf[count++] = IMS_PCU_PROTOCOL_STX;
+
+	/* We know the command need not be escaped */
+	pcu->urb_out_buf[count++] = command;
+	csum += command;
+
+	ack_id = pcu->ack_id++;
+	if (ack_id == 0xff)
+		ack_id = pcu->ack_id++;
+
+	if (ims_pcu_byte_needs_escape(ack_id))
+		pcu->urb_out_buf[count++] = IMS_PCU_PROTOCOL_DLE;
+
+	pcu->urb_out_buf[count++] = ack_id;
+	csum += ack_id;
+
+	for (i = 0; i < len; i++) {
+
+		delta = ims_pcu_byte_needs_escape(data[i]) ? 2 : 1;
+		if (count + delta >= pcu->max_out_size) {
+			error = ims_pcu_send_cmd_chunk(pcu, command,
+						       ++chunk, count);
+			if (error)
+				return error;
+
+			count = 0;
+		}
+
+		if (delta == 2)
+			pcu->urb_out_buf[count++] = IMS_PCU_PROTOCOL_DLE;
+
+		pcu->urb_out_buf[count++] = data[i];
+		csum += data[i];
+	}
+
+	csum = 1 + ~csum;
+
+	delta = ims_pcu_byte_needs_escape(csum) ? 3 : 2;
+	if (count + delta >= pcu->max_out_size) {
+		error = ims_pcu_send_cmd_chunk(pcu, command, ++chunk, count);
+		if (error)
+			return error;
+
+		count = 0;
+	}
+
+	if (delta == 3)
+		pcu->urb_out_buf[count++] = IMS_PCU_PROTOCOL_DLE;
+
+	pcu->urb_out_buf[count++] = csum;
+	pcu->urb_out_buf[count++] = IMS_PCU_PROTOCOL_ETX;
+
+	return ims_pcu_send_cmd_chunk(pcu, command, ++chunk, count);
+}
+
+static int __ims_pcu_execute_command(struct ims_pcu *pcu,
+				     u8 command, const void *data, size_t len,
+				     u8 expected_response, int response_time)
+{
+	int error;
+
+	pcu->expected_response = expected_response;
+	init_completion(&pcu->cmd_done);
+
+	error = ims_pcu_send_command(pcu, command, data, len);
+	if (error)
+		return error;
+
+	if (expected_response &&
+	    !wait_for_completion_timeout(&pcu->cmd_done,
+					 msecs_to_jiffies(response_time))) {
+		dev_dbg(pcu->dev, "Command 0x%02x timed out\n", command);
+		return -ETIMEDOUT;
+	}
+
+	return 0;
+}
+
+#define ims_pcu_execute_command(pcu, code, data, len)			\
+	__ims_pcu_execute_command(pcu,					\
+				  IMS_PCU_CMD_##code, data, len,	\
+				  IMS_PCU_RSP_##code,			\
+				  IMS_PCU_CMD_RESPONSE_TIMEOUT)
+
+#define ims_pcu_execute_query(pcu, code)				\
+	ims_pcu_execute_command(pcu, code, NULL, 0)
+
+/* Bootloader commands */
+#define IMS_PCU_BL_CMD_QUERY_DEVICE	0xa1
+#define IMS_PCU_BL_CMD_UNLOCK_CONFIG	0xa2
+#define IMS_PCU_BL_CMD_ERASE_APP	0xa3
+#define IMS_PCU_BL_CMD_PROGRAM_DEVICE	0xa4
+#define IMS_PCU_BL_CMD_PROGRAM_COMPLETE	0xa5
+#define IMS_PCU_BL_CMD_READ_APP		0xa6
+#define IMS_PCU_BL_CMD_RESET_DEVICE	0xa7
+#define IMS_PCU_BL_CMD_LAUNCH_APP	0xa8
+
+/* Bootloader commands */
+#define IMS_PCU_BL_RSP_QUERY_DEVICE	0xc1
+#define IMS_PCU_BL_RSP_UNLOCK_CONFIG	0xc2
+#define IMS_PCU_BL_RSP_ERASE_APP	0xc3
+#define IMS_PCU_BL_RSP_PROGRAM_DEVICE	0xc4
+#define IMS_PCU_BL_RSP_PROGRAM_COMPLETE	0xc5
+#define IMS_PCU_BL_RSP_READ_APP		0xc6
+#define IMS_PCU_BL_RSP_RESET_DEVICE	0	/* originally 0xa7 */
+#define IMS_PCU_BL_RSP_LAUNCH_APP	0	/* originally 0xa8 */
+
+#define IMS_PCU_BL_DATA_OFFSET		3
+
+static int __ims_pcu_execute_bl_command(struct ims_pcu *pcu,
+				        u8 command, const void *data, size_t len,
+				        u8 expected_response, int response_time)
+{
+	int error;
+
+	pcu->cmd_buf[0] = command;
+	if (data)
+		memcpy(&pcu->cmd_buf[1], data, len);
+
+	error = __ims_pcu_execute_command(pcu,
+				IMS_PCU_CMD_BOOTLOADER, pcu->cmd_buf, len + 1,
+				expected_response ? IMS_PCU_RSP_BOOTLOADER : 0,
+				response_time);
+	if (error) {
+		dev_err(pcu->dev,
+			"Failure when sending 0x%02x command to bootloader, error: %d\n",
+			pcu->cmd_buf[0], error);
+		return error;
+	}
+
+	if (expected_response && pcu->cmd_buf[2] != expected_response) {
+		dev_err(pcu->dev,
+			"Unexpected response from bootloader: 0x%02x, wanted 0x%02x\n",
+			pcu->cmd_buf[2], expected_response);
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+#define ims_pcu_execute_bl_command(pcu, code, data, len, timeout)	\
+	__ims_pcu_execute_bl_command(pcu,				\
+				     IMS_PCU_BL_CMD_##code, data, len,	\
+				     IMS_PCU_BL_RSP_##code, timeout)	\
+
+#define IMS_PCU_INFO_PART_OFFSET	2
+#define IMS_PCU_INFO_DOM_OFFSET		17
+#define IMS_PCU_INFO_SERIAL_OFFSET	25
+
+#define IMS_PCU_SET_INFO_SIZE		31
+
+static int ims_pcu_get_info(struct ims_pcu *pcu)
+{
+	int error;
+
+	error = ims_pcu_execute_query(pcu, GET_INFO);
+	if (error) {
+		dev_err(pcu->dev,
+			"GET_INFO command failed, error: %d\n", error);
+		return error;
+	}
+
+	memcpy(pcu->part_number,
+	       &pcu->cmd_buf[IMS_PCU_INFO_PART_OFFSET],
+	       sizeof(pcu->part_number));
+	memcpy(pcu->date_of_manufacturing,
+	       &pcu->cmd_buf[IMS_PCU_INFO_DOM_OFFSET],
+	       sizeof(pcu->date_of_manufacturing));
+	memcpy(pcu->serial_number,
+	       &pcu->cmd_buf[IMS_PCU_INFO_SERIAL_OFFSET],
+	       sizeof(pcu->serial_number));
+
+	return 0;
+}
+
+static int ims_pcu_set_info(struct ims_pcu *pcu)
+{
+	int error;
+
+	memcpy(&pcu->cmd_buf[IMS_PCU_INFO_PART_OFFSET],
+	       pcu->part_number, sizeof(pcu->part_number));
+	memcpy(&pcu->cmd_buf[IMS_PCU_INFO_DOM_OFFSET],
+	       pcu->date_of_manufacturing, sizeof(pcu->date_of_manufacturing));
+	memcpy(&pcu->cmd_buf[IMS_PCU_INFO_SERIAL_OFFSET],
+	       pcu->serial_number, sizeof(pcu->serial_number));
+
+	error = ims_pcu_execute_command(pcu, SET_INFO,
+					&pcu->cmd_buf[IMS_PCU_DATA_OFFSET],
+					IMS_PCU_SET_INFO_SIZE);
+	if (error) {
+		dev_err(pcu->dev,
+			"Failed to update device information, error: %d\n",
+			error);
+		return error;
+	}
+
+	return 0;
+}
+
+static int ims_pcu_switch_to_bootloader(struct ims_pcu *pcu)
+{
+	int error;
+
+	/* Execute jump to the bootoloader */
+	error = ims_pcu_execute_command(pcu, JUMP_TO_BTLDR, NULL, 0);
+	if (error) {
+		dev_err(pcu->dev,
+			"Failure when sending JUMP TO BOOLTLOADER command, error: %d\n",
+			error);
+		return error;
+	}
+
+	return 0;
+}
+
+/*********************************************************************
+ *             Firmware Update handling                              *
+ *********************************************************************/
+
+#define IMS_PCU_FIRMWARE_NAME	"imspcu.fw"
+
+struct ims_pcu_flash_fmt {
+	__le32 addr;
+	u8 len;
+	u8 data[];
+};
+
+static unsigned int ims_pcu_count_fw_records(const struct firmware *fw)
+{
+	const struct ihex_binrec *rec = (const struct ihex_binrec *)fw->data;
+	unsigned int count = 0;
+
+	while (rec) {
+		count++;
+		rec = ihex_next_binrec(rec);
+	}
+
+	return count;
+}
+
+static int ims_pcu_verify_block(struct ims_pcu *pcu,
+				u32 addr, u8 len, const u8 *data)
+{
+	struct ims_pcu_flash_fmt *fragment;
+	int error;
+
+	fragment = (void *)&pcu->cmd_buf[1];
+	put_unaligned_le32(addr, &fragment->addr);
+	fragment->len = len;
+
+	error = ims_pcu_execute_bl_command(pcu, READ_APP, NULL, 5,
+					IMS_PCU_CMD_RESPONSE_TIMEOUT);
+	if (error) {
+		dev_err(pcu->dev,
+			"Failed to retrieve block at 0x%08x, len %d, error: %d\n",
+			addr, len, error);
+		return error;
+	}
+
+	fragment = (void *)&pcu->cmd_buf[IMS_PCU_BL_DATA_OFFSET];
+	if (get_unaligned_le32(&fragment->addr) != addr ||
+	    fragment->len != len) {
+		dev_err(pcu->dev,
+			"Wrong block when retrieving 0x%08x (0x%08x), len %d (%d)\n",
+			addr, get_unaligned_le32(&fragment->addr),
+			len, fragment->len);
+		return -EINVAL;
+	}
+
+	if (memcmp(fragment->data, data, len)) {
+		dev_err(pcu->dev,
+			"Mismatch in block at 0x%08x, len %d\n",
+			addr, len);
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+static int ims_pcu_flash_firmware(struct ims_pcu *pcu,
+				  const struct firmware *fw,
+				  unsigned int n_fw_records)
+{
+	const struct ihex_binrec *rec = (const struct ihex_binrec *)fw->data;
+	struct ims_pcu_flash_fmt *fragment;
+	unsigned int count = 0;
+	u32 addr;
+	u8 len;
+	int error;
+
+	error = ims_pcu_execute_bl_command(pcu, ERASE_APP, NULL, 0, 2000);
+	if (error) {
+		dev_err(pcu->dev,
+			"Failed to erase application image, error: %d\n",
+			error);
+		return error;
+	}
+
+	while (rec) {
+		/*
+		 * The firmware format is messed up for some reason.
+		 * The address twice that of what is needed for some
+		 * reason and we end up overwriting half of the data
+		 * with the next record.
+		 */
+		addr = be32_to_cpu(rec->addr) / 2;
+		len = be16_to_cpu(rec->len);
+
+		fragment = (void *)&pcu->cmd_buf[1];
+		put_unaligned_le32(addr, &fragment->addr);
+		fragment->len = len;
+		memcpy(fragment->data, rec->data, len);
+
+		error = ims_pcu_execute_bl_command(pcu, PROGRAM_DEVICE,
+						NULL, len + 5,
+						IMS_PCU_CMD_RESPONSE_TIMEOUT);
+		if (error) {
+			dev_err(pcu->dev,
+				"Failed to write block at 0x%08x, len %d, error: %d\n",
+				addr, len, error);
+			return error;
+		}
+
+		if (addr >= pcu->fw_start_addr && addr < pcu->fw_end_addr) {
+			error = ims_pcu_verify_block(pcu, addr, len, rec->data);
+			if (error)
+				return error;
+		}
+
+		count++;
+		pcu->update_firmware_status = (count * 100) / n_fw_records;
+
+		rec = ihex_next_binrec(rec);
+	}
+
+	error = ims_pcu_execute_bl_command(pcu, PROGRAM_COMPLETE,
+					    NULL, 0, 2000);
+	if (error)
+		dev_err(pcu->dev,
+			"Failed to send PROGRAM_COMPLETE, error: %d\n",
+			error);
+
+	return 0;
+}
+
+static int ims_pcu_handle_firmware_update(struct ims_pcu *pcu,
+					  const struct firmware *fw)
+{
+	unsigned int n_fw_records;
+	int retval;
+
+	dev_info(pcu->dev, "Updating firmware %s, size: %zu\n",
+		 IMS_PCU_FIRMWARE_NAME, fw->size);
+
+	n_fw_records = ims_pcu_count_fw_records(fw);
+
+	retval = ims_pcu_flash_firmware(pcu, fw, n_fw_records);
+	if (retval)
+		goto out;
+
+	retval = ims_pcu_execute_bl_command(pcu, LAUNCH_APP, NULL, 0, 0);
+	if (retval)
+		dev_err(pcu->dev,
+			"Failed to start application image, error: %d\n",
+			retval);
+
+out:
+	pcu->update_firmware_status = retval;
+	sysfs_notify(&pcu->dev->kobj, NULL, "update_firmware_status");
+	return retval;
+}
+
+static void ims_pcu_process_async_firmware(const struct firmware *fw,
+					   void *context)
+{
+	struct ims_pcu *pcu = context;
+	int error;
+
+	if (!fw) {
+		dev_err(pcu->dev, "Failed to get firmware %s\n",
+			IMS_PCU_FIRMWARE_NAME);
+		goto out;
+	}
+
+	error = ihex_validate_fw(fw);
+	if (error) {
+		dev_err(pcu->dev, "Firmware %s is invalid\n",
+			IMS_PCU_FIRMWARE_NAME);
+		goto out;
+	}
+
+	mutex_lock(&pcu->cmd_mutex);
+	ims_pcu_handle_firmware_update(pcu, fw);
+	mutex_unlock(&pcu->cmd_mutex);
+
+	release_firmware(fw);
+
+out:
+	complete(&pcu->async_firmware_done);
+}
+
+/*********************************************************************
+ *             Backlight LED device support                          *
+ *********************************************************************/
+
+#define IMS_PCU_MAX_BRIGHTNESS		31998
+
+static void ims_pcu_backlight_work(struct work_struct *work)
+{
+	struct ims_pcu_backlight *backlight =
+			container_of(work, struct ims_pcu_backlight, work);
+	struct ims_pcu *pcu =
+			container_of(backlight, struct ims_pcu, backlight);
+	int desired_brightness = backlight->desired_brightness;
+	__le16 br_val = cpu_to_le16(desired_brightness);
+	int error;
+
+	mutex_lock(&pcu->cmd_mutex);
+
+	error = ims_pcu_execute_command(pcu, SET_BRIGHTNESS,
+					&br_val, sizeof(br_val));
+	if (error && error != -ENODEV)
+		dev_warn(pcu->dev,
+			 "Failed to set desired brightness %u, error: %d\n",
+			 desired_brightness, error);
+
+	mutex_unlock(&pcu->cmd_mutex);
+}
+
+static void ims_pcu_backlight_set_brightness(struct led_classdev *cdev,
+					     enum led_brightness value)
+{
+	struct ims_pcu_backlight *backlight =
+			container_of(cdev, struct ims_pcu_backlight, cdev);
+
+	backlight->desired_brightness = value;
+	schedule_work(&backlight->work);
+}
+
+static enum led_brightness
+ims_pcu_backlight_get_brightness(struct led_classdev *cdev)
+{
+	struct ims_pcu_backlight *backlight =
+			container_of(cdev, struct ims_pcu_backlight, cdev);
+	struct ims_pcu *pcu =
+			container_of(backlight, struct ims_pcu, backlight);
+	int brightness;
+	int error;
+
+	mutex_lock(&pcu->cmd_mutex);
+
+	error = ims_pcu_execute_query(pcu, GET_BRIGHTNESS);
+	if (error) {
+		dev_warn(pcu->dev,
+			 "Failed to get current brightness, error: %d\n",
+			 error);
+		/* Assume the LED is OFF */
+		brightness = LED_OFF;
+	} else {
+		brightness =
+			get_unaligned_le16(&pcu->cmd_buf[IMS_PCU_DATA_OFFSET]);
+	}
+
+	mutex_unlock(&pcu->cmd_mutex);
+
+	return brightness;
+}
+
+static int ims_pcu_setup_backlight(struct ims_pcu *pcu)
+{
+	struct ims_pcu_backlight *backlight = &pcu->backlight;
+	int error;
+
+	INIT_WORK(&backlight->work, ims_pcu_backlight_work);
+	snprintf(backlight->name, sizeof(backlight->name),
+		 "pcu%d::kbd_backlight", pcu->device_no);
+
+	backlight->cdev.name = backlight->name;
+	backlight->cdev.max_brightness = IMS_PCU_MAX_BRIGHTNESS;
+	backlight->cdev.brightness_get = ims_pcu_backlight_get_brightness;
+	backlight->cdev.brightness_set = ims_pcu_backlight_set_brightness;
+
+	error = led_classdev_register(pcu->dev, &backlight->cdev);
+	if (error) {
+		dev_err(pcu->dev,
+			"Failed to register backlight LED device, error: %d\n",
+			error);
+		return error;
+	}
+
+	return 0;
+}
+
+static void ims_pcu_destroy_backlight(struct ims_pcu *pcu)
+{
+	struct ims_pcu_backlight *backlight = &pcu->backlight;
+
+	led_classdev_unregister(&backlight->cdev);
+	cancel_work_sync(&backlight->work);
+}
+
+
+/*********************************************************************
+ *             Sysfs attributes handling                             *
+ *********************************************************************/
+
+struct ims_pcu_attribute {
+	struct device_attribute dattr;
+	size_t field_offset;
+	int field_length;
+};
+
+static ssize_t ims_pcu_attribute_show(struct device *dev,
+				      struct device_attribute *dattr,
+				      char *buf)
+{
+	struct usb_interface *intf = to_usb_interface(dev);
+	struct ims_pcu *pcu = usb_get_intfdata(intf);
+	struct ims_pcu_attribute *attr =
+			container_of(dattr, struct ims_pcu_attribute, dattr);
+	char *field = (char *)pcu + attr->field_offset;
+
+	return scnprintf(buf, PAGE_SIZE, "%.*s\n", attr->field_length, field);
+}
+
+static ssize_t ims_pcu_attribute_store(struct device *dev,
+				       struct device_attribute *dattr,
+				       const char *buf, size_t count)
+{
+
+	struct usb_interface *intf = to_usb_interface(dev);
+	struct ims_pcu *pcu = usb_get_intfdata(intf);
+	struct ims_pcu_attribute *attr =
+			container_of(dattr, struct ims_pcu_attribute, dattr);
+	char *field = (char *)pcu + attr->field_offset;
+	size_t data_len;
+	int error;
+
+	if (count > attr->field_length)
+		return -EINVAL;
+
+	data_len = strnlen(buf, attr->field_length);
+	if (data_len > attr->field_length)
+		return -EINVAL;
+
+	error = mutex_lock_interruptible(&pcu->cmd_mutex);
+	if (error)
+		return error;
+
+	memset(field, 0, attr->field_length);
+	memcpy(field, buf, data_len);
+
+	error = ims_pcu_set_info(pcu);
+
+	/*
+	 * Even if update failed, let's fetch the info again as we just
+	 * clobbered one of the fields.
+	 */
+	ims_pcu_get_info(pcu);
+
+	mutex_unlock(&pcu->cmd_mutex);
+
+	return error < 0 ? error : count;
+}
+
+#define IMS_PCU_ATTR(_field, _mode)					\
+struct ims_pcu_attribute ims_pcu_attr_##_field = {			\
+	.dattr = __ATTR(_field, _mode,					\
+			ims_pcu_attribute_show,				\
+			ims_pcu_attribute_store),			\
+	.field_offset = offsetof(struct ims_pcu, _field),		\
+	.field_length = sizeof(((struct ims_pcu *)NULL)->_field),	\
+}
+
+#define IMS_PCU_RO_ATTR(_field)						\
+		IMS_PCU_ATTR(_field, S_IRUGO)
+#define IMS_PCU_RW_ATTR(_field)						\
+		IMS_PCU_ATTR(_field, S_IRUGO | S_IWUSR)
+
+static IMS_PCU_RW_ATTR(part_number);
+static IMS_PCU_RW_ATTR(serial_number);
+static IMS_PCU_RW_ATTR(date_of_manufacturing);
+
+static IMS_PCU_RO_ATTR(fw_version);
+static IMS_PCU_RO_ATTR(bl_version);
+static IMS_PCU_RO_ATTR(reset_reason);
+
+static ssize_t ims_pcu_reset_device(struct device *dev,
+				    struct device_attribute *dattr,
+				    const char *buf, size_t count)
+{
+	static const u8 reset_byte = 1;
+	struct usb_interface *intf = to_usb_interface(dev);
+	struct ims_pcu *pcu = usb_get_intfdata(intf);
+	int value;
+	int error;
+
+	error = kstrtoint(buf, 0, &value);
+	if (error)
+		return error;
+
+	if (value != 1)
+		return -EINVAL;
+
+	dev_info(pcu->dev, "Attempting to reset device\n");
+
+	error = ims_pcu_execute_command(pcu, PCU_RESET, &reset_byte, 1);
+	if (error) {
+		dev_info(pcu->dev,
+			 "Failed to reset device, error: %d\n",
+			 error);
+		return error;
+	}
+
+	return count;
+}
+
+static DEVICE_ATTR(reset_device, S_IWUSR, NULL, ims_pcu_reset_device);
+
+static ssize_t ims_pcu_update_firmware_store(struct device *dev,
+					     struct device_attribute *dattr,
+					     const char *buf, size_t count)
+{
+	struct usb_interface *intf = to_usb_interface(dev);
+	struct ims_pcu *pcu = usb_get_intfdata(intf);
+	const struct firmware *fw;
+	int value;
+	int error;
+
+	error = kstrtoint(buf, 0, &value);
+	if (error)
+		return error;
+
+	if (value != 1)
+		return -EINVAL;
+
+	error = mutex_lock_interruptible(&pcu->cmd_mutex);
+	if (error)
+		return error;
+
+	error = request_ihex_firmware(&fw, IMS_PCU_FIRMWARE_NAME, pcu->dev);
+	if (error) {
+		dev_err(pcu->dev, "Failed to request firmware %s, error: %d\n",
+			IMS_PCU_FIRMWARE_NAME, error);
+		goto out;
+	}
+
+	/*
+	 * If we are already in bootloader mode we can proceed with
+	 * flashing the firmware.
+	 *
+	 * If we are in application mode, then we need to switch into
+	 * bootloader mode, which will cause the device to disconnect
+	 * and reconnect as different device.
+	 */
+	if (pcu->bootloader_mode)
+		error = ims_pcu_handle_firmware_update(pcu, fw);
+	else
+		error = ims_pcu_switch_to_bootloader(pcu);
+
+	release_firmware(fw);
+
+out:
+	mutex_unlock(&pcu->cmd_mutex);
+	return error ?: count;
+}
+
+static DEVICE_ATTR(update_firmware, S_IWUSR,
+		   NULL, ims_pcu_update_firmware_store);
+
+static ssize_t
+ims_pcu_update_firmware_status_show(struct device *dev,
+				    struct device_attribute *dattr,
+				    char *buf)
+{
+	struct usb_interface *intf = to_usb_interface(dev);
+	struct ims_pcu *pcu = usb_get_intfdata(intf);
+
+	return scnprintf(buf, PAGE_SIZE, "%d\n", pcu->update_firmware_status);
+}
+
+static DEVICE_ATTR(update_firmware_status, S_IRUGO,
+		   ims_pcu_update_firmware_status_show, NULL);
+
+static struct attribute *ims_pcu_attrs[] = {
+	&ims_pcu_attr_part_number.dattr.attr,
+	&ims_pcu_attr_serial_number.dattr.attr,
+	&ims_pcu_attr_date_of_manufacturing.dattr.attr,
+	&ims_pcu_attr_fw_version.dattr.attr,
+	&ims_pcu_attr_bl_version.dattr.attr,
+	&ims_pcu_attr_reset_reason.dattr.attr,
+	&dev_attr_reset_device.attr,
+	&dev_attr_update_firmware.attr,
+	&dev_attr_update_firmware_status.attr,
+	NULL
+};
+
+static umode_t ims_pcu_is_attr_visible(struct kobject *kobj,
+				       struct attribute *attr, int n)
+{
+	struct device *dev = container_of(kobj, struct device, kobj);
+	struct usb_interface *intf = to_usb_interface(dev);
+	struct ims_pcu *pcu = usb_get_intfdata(intf);
+	umode_t mode = attr->mode;
+
+	if (pcu->bootloader_mode) {
+		if (attr != &dev_attr_update_firmware_status.attr &&
+		    attr != &dev_attr_update_firmware.attr &&
+		    attr != &dev_attr_reset_device.attr) {
+			mode = 0;
+		}
+	} else {
+		if (attr == &dev_attr_update_firmware_status.attr)
+			mode = 0;
+	}
+
+	return mode;
+}
+
+static struct attribute_group ims_pcu_attr_group = {
+	.is_visible	= ims_pcu_is_attr_visible,
+	.attrs		= ims_pcu_attrs,
+};
+
+static void ims_pcu_irq(struct urb *urb)
+{
+	struct ims_pcu *pcu = urb->context;
+	int retval, status;
+
+	status = urb->status;
+
+	switch (status) {
+	case 0:
+		/* success */
+		break;
+	case -ECONNRESET:
+	case -ENOENT:
+	case -ESHUTDOWN:
+		/* this urb is terminated, clean up */
+		dev_dbg(pcu->dev, "%s - urb shutting down with status: %d\n",
+			__func__, status);
+		return;
+	default:
+		dev_dbg(pcu->dev, "%s - nonzero urb status received: %d\n",
+			__func__, status);
+		goto exit;
+	}
+
+	dev_dbg(pcu->dev, "%s: received %d: %*ph\n", __func__,
+		urb->actual_length, urb->actual_length, pcu->urb_in_buf);
+
+	if (urb == pcu->urb_in)
+		ims_pcu_process_data(pcu, urb);
+
+exit:
+	retval = usb_submit_urb(urb, GFP_ATOMIC);
+	if (retval && retval != -ENODEV)
+		dev_err(pcu->dev, "%s - usb_submit_urb failed with result %d\n",
+			__func__, retval);
+}
+
+static int ims_pcu_buffers_alloc(struct ims_pcu *pcu)
+{
+	int error;
+
+	pcu->urb_in_buf = usb_alloc_coherent(pcu->udev, pcu->max_in_size,
+					     GFP_KERNEL, &pcu->read_dma);
+	if (!pcu->urb_in_buf) {
+		dev_err(pcu->dev,
+			"Failed to allocate memory for read buffer\n");
+		return -ENOMEM;
+	}
+
+	pcu->urb_in = usb_alloc_urb(0, GFP_KERNEL);
+	if (!pcu->urb_in) {
+		dev_err(pcu->dev, "Failed to allocate input URB\n");
+		error = -ENOMEM;
+		goto err_free_urb_in_buf;
+	}
+
+	pcu->urb_in->transfer_flags |= URB_NO_TRANSFER_DMA_MAP;
+	pcu->urb_in->transfer_dma = pcu->read_dma;
+
+	usb_fill_bulk_urb(pcu->urb_in, pcu->udev,
+			  usb_rcvbulkpipe(pcu->udev,
+					  pcu->ep_in->bEndpointAddress),
+			  pcu->urb_in_buf, pcu->max_in_size,
+			  ims_pcu_irq, pcu);
+
+	/*
+	 * We are using usb_bulk_msg() for sending so there is no point
+	 * in allocating memory with usb_alloc_coherent().
+	 */
+	pcu->urb_out_buf = kmalloc(pcu->max_out_size, GFP_KERNEL);
+	if (!pcu->urb_out_buf) {
+		dev_err(pcu->dev, "Failed to allocate memory for write buffer\n");
+		error = -ENOMEM;
+		goto err_free_in_urb;
+	}
+
+	pcu->urb_ctrl_buf = usb_alloc_coherent(pcu->udev, pcu->max_ctrl_size,
+					       GFP_KERNEL, &pcu->ctrl_dma);
+	if (!pcu->urb_ctrl_buf) {
+		dev_err(pcu->dev,
+			"Failed to allocate memory for read buffer\n");
+		goto err_free_urb_out_buf;
+	}
+
+	pcu->urb_ctrl = usb_alloc_urb(0, GFP_KERNEL);
+	if (!pcu->urb_ctrl) {
+		dev_err(pcu->dev, "Failed to allocate input URB\n");
+		error = -ENOMEM;
+		goto err_free_urb_ctrl_buf;
+	}
+
+	pcu->urb_ctrl->transfer_flags |= URB_NO_TRANSFER_DMA_MAP;
+	pcu->urb_ctrl->transfer_dma = pcu->ctrl_dma;
+
+	usb_fill_int_urb(pcu->urb_ctrl, pcu->udev,
+			  usb_rcvintpipe(pcu->udev,
+					 pcu->ep_ctrl->bEndpointAddress),
+			  pcu->urb_ctrl_buf, pcu->max_ctrl_size,
+			  ims_pcu_irq, pcu, pcu->ep_ctrl->bInterval);
+
+	return 0;
+
+err_free_urb_ctrl_buf:
+	usb_free_coherent(pcu->udev, pcu->max_ctrl_size,
+			  pcu->urb_ctrl_buf, pcu->ctrl_dma);
+err_free_urb_out_buf:
+	kfree(pcu->urb_out_buf);
+err_free_in_urb:
+	usb_free_urb(pcu->urb_in);
+err_free_urb_in_buf:
+	usb_free_coherent(pcu->udev, pcu->max_in_size,
+			  pcu->urb_in_buf, pcu->read_dma);
+	return error;
+}
+
+static void ims_pcu_buffers_free(struct ims_pcu *pcu)
+{
+	usb_kill_urb(pcu->urb_in);
+	usb_free_urb(pcu->urb_in);
+
+	usb_free_coherent(pcu->udev, pcu->max_out_size,
+			  pcu->urb_in_buf, pcu->read_dma);
+
+	kfree(pcu->urb_out_buf);
+
+	usb_kill_urb(pcu->urb_ctrl);
+	usb_free_urb(pcu->urb_ctrl);
+
+	usb_free_coherent(pcu->udev, pcu->max_ctrl_size,
+			  pcu->urb_ctrl_buf, pcu->ctrl_dma);
+}
+
+static const struct usb_cdc_union_desc *
+ims_pcu_get_cdc_union_desc(struct usb_interface *intf)
+{
+	const void *buf = intf->altsetting->extra;
+	size_t buflen = intf->altsetting->extralen;
+	struct usb_cdc_union_desc *union_desc;
+
+	if (!buf) {
+		dev_err(&intf->dev, "Missing descriptor data\n");
+		return NULL;
+	}
+
+	if (!buflen) {
+		dev_err(&intf->dev, "Zero length descriptor\n");
+		return NULL;
+	}
+
+	while (buflen > 0) {
+		union_desc = (struct usb_cdc_union_desc *)buf;
+
+		if (union_desc->bDescriptorType == USB_DT_CS_INTERFACE &&
+		    union_desc->bDescriptorSubType == USB_CDC_UNION_TYPE) {
+			dev_dbg(&intf->dev, "Found union header\n");
+			return union_desc;
+		}
+
+		buflen -= union_desc->bLength;
+		buf += union_desc->bLength;
+	}
+
+	dev_err(&intf->dev, "Missing CDC union descriptor\n");
+	return NULL;
+}
+
+static int ims_pcu_parse_cdc_data(struct usb_interface *intf, struct ims_pcu *pcu)
+{
+	const struct usb_cdc_union_desc *union_desc;
+	struct usb_host_interface *alt;
+
+	union_desc = ims_pcu_get_cdc_union_desc(intf);
+	if (!union_desc)
+		return -EINVAL;
+
+	pcu->ctrl_intf = usb_ifnum_to_if(pcu->udev,
+					 union_desc->bMasterInterface0);
+
+	alt = pcu->ctrl_intf->cur_altsetting;
+	pcu->ep_ctrl = &alt->endpoint[0].desc;
+	pcu->max_ctrl_size = usb_endpoint_maxp(pcu->ep_ctrl);
+
+	pcu->data_intf = usb_ifnum_to_if(pcu->udev,
+					 union_desc->bSlaveInterface0);
+
+	alt = pcu->data_intf->cur_altsetting;
+	if (alt->desc.bNumEndpoints != 2) {
+		dev_err(pcu->dev,
+			"Incorrect number of endpoints on data interface (%d)\n",
+			alt->desc.bNumEndpoints);
+		return -EINVAL;
+	}
+
+	pcu->ep_out = &alt->endpoint[0].desc;
+	if (!usb_endpoint_is_bulk_out(pcu->ep_out)) {
+		dev_err(pcu->dev,
+			"First endpoint on data interface is not BULK OUT\n");
+		return -EINVAL;
+	}
+
+	pcu->max_out_size = usb_endpoint_maxp(pcu->ep_out);
+	if (pcu->max_out_size < 8) {
+		dev_err(pcu->dev,
+			"Max OUT packet size is too small (%zd)\n",
+			pcu->max_out_size);
+		return -EINVAL;
+	}
+
+	pcu->ep_in = &alt->endpoint[1].desc;
+	if (!usb_endpoint_is_bulk_in(pcu->ep_in)) {
+		dev_err(pcu->dev,
+			"Second endpoint on data interface is not BULK IN\n");
+		return -EINVAL;
+	}
+
+	pcu->max_in_size = usb_endpoint_maxp(pcu->ep_in);
+	if (pcu->max_in_size < 8) {
+		dev_err(pcu->dev,
+			"Max IN packet size is too small (%zd)\n",
+			pcu->max_in_size);
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+static int ims_pcu_start_io(struct ims_pcu *pcu)
+{
+	int error;
+
+	error = usb_submit_urb(pcu->urb_ctrl, GFP_KERNEL);
+	if (error) {
+		dev_err(pcu->dev,
+			"Failed to start control IO - usb_submit_urb failed with result: %d\n",
+			error);
+		return -EIO;
+	}
+
+	error = usb_submit_urb(pcu->urb_in, GFP_KERNEL);
+	if (error) {
+		dev_err(pcu->dev,
+			"Failed to start IO - usb_submit_urb failed with result: %d\n",
+			error);
+		usb_kill_urb(pcu->urb_ctrl);
+		return -EIO;
+	}
+
+	return 0;
+}
+
+static void ims_pcu_stop_io(struct ims_pcu *pcu)
+{
+	usb_kill_urb(pcu->urb_in);
+	usb_kill_urb(pcu->urb_ctrl);
+}
+
+static int ims_pcu_line_setup(struct ims_pcu *pcu)
+{
+	struct usb_host_interface *interface = pcu->ctrl_intf->cur_altsetting;
+	struct usb_cdc_line_coding *line = (void *)pcu->cmd_buf;
+	int error;
+
+	memset(line, 0, sizeof(*line));
+	line->dwDTERate = cpu_to_le32(57600);
+	line->bDataBits = 8;
+
+	error = usb_control_msg(pcu->udev, usb_sndctrlpipe(pcu->udev, 0),
+				USB_CDC_REQ_SET_LINE_CODING,
+				USB_TYPE_CLASS | USB_RECIP_INTERFACE,
+				0, interface->desc.bInterfaceNumber,
+				line, sizeof(struct usb_cdc_line_coding),
+				5000);
+	if (error < 0) {
+		dev_err(pcu->dev, "Failed to set line coding, error: %d\n",
+			error);
+		return error;
+	}
+
+	error = usb_control_msg(pcu->udev, usb_sndctrlpipe(pcu->udev, 0),
+				USB_CDC_REQ_SET_CONTROL_LINE_STATE,
+				USB_TYPE_CLASS | USB_RECIP_INTERFACE,
+				0x03, interface->desc.bInterfaceNumber,
+				NULL, 0, 5000);
+	if (error < 0) {
+		dev_err(pcu->dev, "Failed to set line state, error: %d\n",
+			error);
+		return error;
+	}
+
+	return 0;
+}
+
+static int ims_pcu_get_device_info(struct ims_pcu *pcu)
+{
+	int error;
+
+	error = ims_pcu_get_info(pcu);
+	if (error)
+		return error;
+
+	error = ims_pcu_execute_query(pcu, GET_FW_VERSION);
+	if (error) {
+		dev_err(pcu->dev,
+			"GET_FW_VERSION command failed, error: %d\n", error);
+		return error;
+	}
+
+	snprintf(pcu->fw_version, sizeof(pcu->fw_version),
+		 "%02d%02d%02d%02d.%c%c",
+		 pcu->cmd_buf[2], pcu->cmd_buf[3], pcu->cmd_buf[4], pcu->cmd_buf[5],
+		 pcu->cmd_buf[6], pcu->cmd_buf[7]);
+
+	error = ims_pcu_execute_query(pcu, GET_BL_VERSION);
+	if (error) {
+		dev_err(pcu->dev,
+			"GET_BL_VERSION command failed, error: %d\n", error);
+		return error;
+	}
+
+	snprintf(pcu->bl_version, sizeof(pcu->bl_version),
+		 "%02d%02d%02d%02d.%c%c",
+		 pcu->cmd_buf[2], pcu->cmd_buf[3], pcu->cmd_buf[4], pcu->cmd_buf[5],
+		 pcu->cmd_buf[6], pcu->cmd_buf[7]);
+
+	error = ims_pcu_execute_query(pcu, RESET_REASON);
+	if (error) {
+		dev_err(pcu->dev,
+			"RESET_REASON command failed, error: %d\n", error);
+		return error;
+	}
+
+	snprintf(pcu->reset_reason, sizeof(pcu->reset_reason),
+		 "%02x", pcu->cmd_buf[IMS_PCU_DATA_OFFSET]);
+
+	dev_dbg(pcu->dev,
+		"P/N: %s, MD: %s, S/N: %s, FW: %s, BL: %s, RR: %s\n",
+		pcu->part_number,
+		pcu->date_of_manufacturing,
+		pcu->serial_number,
+		pcu->fw_version,
+		pcu->bl_version,
+		pcu->reset_reason);
+
+	return 0;
+}
+
+static int ims_pcu_identify_type(struct ims_pcu *pcu, u8 *device_id)
+{
+	int error;
+
+	error = ims_pcu_execute_query(pcu, GET_DEVICE_ID);
+	if (error) {
+		dev_err(pcu->dev,
+			"GET_DEVICE_ID command failed, error: %d\n", error);
+		return error;
+	}
+
+	*device_id = pcu->cmd_buf[IMS_PCU_DATA_OFFSET];
+	dev_dbg(pcu->dev, "Detected device ID: %d\n", *device_id);
+
+	return 0;
+}
+
+static int ims_pcu_init_application_mode(struct ims_pcu *pcu)
+{
+	static atomic_t device_no = ATOMIC_INIT(0);
+
+	const struct ims_pcu_device_info *info;
+	u8 device_id;
+	int error;
+
+	error = ims_pcu_get_device_info(pcu);
+	if (error) {
+		/* Device does not respond to basic queries, hopeless */
+		return error;
+	}
+
+	error = ims_pcu_identify_type(pcu, &device_id);
+	if (error) {
+		dev_err(pcu->dev,
+			"Failed to identify device, error: %d\n", error);
+		/*
+		 * Do not signal error, but do not create input nor
+		 * backlight devices either, let userspace figure this
+		 * out (flash a new firmware?).
+		 */
+		return 0;
+	}
+
+	if (device_id >= ARRAY_SIZE(ims_pcu_device_info) ||
+	    !ims_pcu_device_info[device_id].keymap) {
+		dev_err(pcu->dev, "Device ID %d is not valid\n", device_id);
+		/* Same as above, punt to userspace */
+		return 0;
+	}
+
+	/* Device appears to be operable, complete initialization */
+	pcu->device_no = atomic_inc_return(&device_no) - 1;
+
+	error = ims_pcu_setup_backlight(pcu);
+	if (error)
+		return error;
+
+	info = &ims_pcu_device_info[device_id];
+	error = ims_pcu_setup_buttons(pcu, info->keymap, info->keymap_len);
+	if (error)
+		goto err_destroy_backlight;
+
+	if (info->has_gamepad) {
+		error = ims_pcu_setup_gamepad(pcu);
+		if (error)
+			goto err_destroy_buttons;
+	}
+
+	pcu->setup_complete = true;
+
+	return 0;
+
+err_destroy_backlight:
+	ims_pcu_destroy_backlight(pcu);
+err_destroy_buttons:
+	ims_pcu_destroy_buttons(pcu);
+	return error;
+}
+
+static void ims_pcu_destroy_application_mode(struct ims_pcu *pcu)
+{
+	if (pcu->setup_complete) {
+		pcu->setup_complete = false;
+		mb(); /* make sure flag setting is not reordered */
+
+		if (pcu->gamepad)
+			ims_pcu_destroy_gamepad(pcu);
+		ims_pcu_destroy_buttons(pcu);
+		ims_pcu_destroy_backlight(pcu);
+	}
+}
+
+static int ims_pcu_init_bootloader_mode(struct ims_pcu *pcu)
+{
+	int error;
+
+	error = ims_pcu_execute_bl_command(pcu, QUERY_DEVICE, NULL, 0,
+					   IMS_PCU_CMD_RESPONSE_TIMEOUT);
+	if (error) {
+		dev_err(pcu->dev, "Bootloader does not respond, aborting\n");
+		return error;
+	}
+
+	pcu->fw_start_addr =
+		get_unaligned_le32(&pcu->cmd_buf[IMS_PCU_DATA_OFFSET + 11]);
+	pcu->fw_end_addr =
+		get_unaligned_le32(&pcu->cmd_buf[IMS_PCU_DATA_OFFSET + 15]);
+
+	dev_info(pcu->dev,
+		 "Device is in bootloader mode (addr 0x%08x-0x%08x), requesting firmware\n",
+		 pcu->fw_start_addr, pcu->fw_end_addr);
+
+	error = request_firmware_nowait(THIS_MODULE, true,
+					IMS_PCU_FIRMWARE_NAME,
+					pcu->dev, GFP_KERNEL, pcu,
+					ims_pcu_process_async_firmware);
+	if (error) {
+		/* This error is not fatal, let userspace have another chance */
+		complete(&pcu->async_firmware_done);
+	}
+
+	return 0;
+}
+
+static void ims_pcu_destroy_bootloader_mode(struct ims_pcu *pcu)
+{
+	/* Make sure our initial firmware request has completed */
+	wait_for_completion(&pcu->async_firmware_done);
+}
+
+#define IMS_PCU_APPLICATION_MODE	0
+#define IMS_PCU_BOOTLOADER_MODE		1
+
+static struct usb_driver ims_pcu_driver;
+
+static int ims_pcu_probe(struct usb_interface *intf,
+			 const struct usb_device_id *id)
+{
+	struct usb_device *udev = interface_to_usbdev(intf);
+	struct ims_pcu *pcu;
+	int error;
+
+	pcu = kzalloc(sizeof(struct ims_pcu), GFP_KERNEL);
+	if (!pcu)
+		return -ENOMEM;
+
+	pcu->dev = &intf->dev;
+	pcu->udev = udev;
+	pcu->bootloader_mode = id->driver_info == IMS_PCU_BOOTLOADER_MODE;
+	mutex_init(&pcu->cmd_mutex);
+	init_completion(&pcu->cmd_done);
+	init_completion(&pcu->async_firmware_done);
+
+	error = ims_pcu_parse_cdc_data(intf, pcu);
+	if (error)
+		goto err_free_mem;
+
+	error = usb_driver_claim_interface(&ims_pcu_driver,
+					   pcu->data_intf, pcu);
+	if (error) {
+		dev_err(&intf->dev,
+			"Unable to claim corresponding data interface: %d\n",
+			error);
+		goto err_free_mem;
+	}
+
+	usb_set_intfdata(pcu->ctrl_intf, pcu);
+	usb_set_intfdata(pcu->data_intf, pcu);
+
+	error = ims_pcu_buffers_alloc(pcu);
+	if (error)
+		goto err_unclaim_intf;
+
+	error = ims_pcu_start_io(pcu);
+	if (error)
+		goto err_free_buffers;
+
+	error = ims_pcu_line_setup(pcu);
+	if (error)
+		goto err_stop_io;
+
+	error = sysfs_create_group(&intf->dev.kobj, &ims_pcu_attr_group);
+	if (error)
+		goto err_stop_io;
+
+	error = pcu->bootloader_mode ?
+			ims_pcu_init_bootloader_mode(pcu) :
+			ims_pcu_init_application_mode(pcu);
+	if (error)
+		goto err_remove_sysfs;
+
+	return 0;
+
+err_remove_sysfs:
+	sysfs_remove_group(&intf->dev.kobj, &ims_pcu_attr_group);
+err_stop_io:
+	ims_pcu_stop_io(pcu);
+err_free_buffers:
+	ims_pcu_buffers_free(pcu);
+err_unclaim_intf:
+	usb_driver_release_interface(&ims_pcu_driver, pcu->data_intf);
+err_free_mem:
+	kfree(pcu);
+	return error;
+}
+
+static void ims_pcu_disconnect(struct usb_interface *intf)
+{
+	struct ims_pcu *pcu = usb_get_intfdata(intf);
+	struct usb_host_interface *alt = intf->cur_altsetting;
+
+	usb_set_intfdata(intf, NULL);
+
+	/*
+	 * See if we are dealing with control or data interface. The cleanup
+	 * happens when we unbind primary (control) interface.
+	 */
+	if (alt->desc.bInterfaceClass != USB_CLASS_COMM)
+		return;
+
+	sysfs_remove_group(&intf->dev.kobj, &ims_pcu_attr_group);
+
+	ims_pcu_stop_io(pcu);
+
+	if (pcu->bootloader_mode)
+		ims_pcu_destroy_bootloader_mode(pcu);
+	else
+		ims_pcu_destroy_application_mode(pcu);
+
+	ims_pcu_buffers_free(pcu);
+	kfree(pcu);
+}
+
+#ifdef CONFIG_PM
+static int ims_pcu_suspend(struct usb_interface *intf,
+			   pm_message_t message)
+{
+	struct ims_pcu *pcu = usb_get_intfdata(intf);
+	struct usb_host_interface *alt = intf->cur_altsetting;
+
+	if (alt->desc.bInterfaceClass == USB_CLASS_COMM)
+		ims_pcu_stop_io(pcu);
+
+	return 0;
+}
+
+static int ims_pcu_resume(struct usb_interface *intf)
+{
+	struct ims_pcu *pcu = usb_get_intfdata(intf);
+	struct usb_host_interface *alt = intf->cur_altsetting;
+	int retval = 0;
+
+	if (alt->desc.bInterfaceClass == USB_CLASS_COMM) {
+		retval = ims_pcu_start_io(pcu);
+		if (retval == 0)
+			retval = ims_pcu_line_setup(pcu);
+	}
+
+	return retval;
+}
+#endif
+
+static const struct usb_device_id ims_pcu_id_table[] = {
+	{
+		USB_DEVICE_AND_INTERFACE_INFO(0x04d8, 0x0082,
+					USB_CLASS_COMM,
+					USB_CDC_SUBCLASS_ACM,
+					USB_CDC_ACM_PROTO_AT_V25TER),
+		.driver_info = IMS_PCU_APPLICATION_MODE,
+	},
+	{
+		USB_DEVICE_AND_INTERFACE_INFO(0x04d8, 0x0083,
+					USB_CLASS_COMM,
+					USB_CDC_SUBCLASS_ACM,
+					USB_CDC_ACM_PROTO_AT_V25TER),
+		.driver_info = IMS_PCU_BOOTLOADER_MODE,
+	},
+	{ }
+};
+
+static struct usb_driver ims_pcu_driver = {
+	.name			= "ims_pcu",
+	.id_table		= ims_pcu_id_table,
+	.probe			= ims_pcu_probe,
+	.disconnect		= ims_pcu_disconnect,
+#ifdef CONFIG_PM
+	.suspend		= ims_pcu_suspend,
+	.resume			= ims_pcu_resume,
+	.reset_resume		= ims_pcu_resume,
+#endif
+};
+
+module_usb_driver(ims_pcu_driver);
+
+MODULE_DESCRIPTION("IMS Passenger Control Unit driver");
+MODULE_AUTHOR("Dmitry Torokhov <dmitry.torokhov@gmail.com>");
+MODULE_LICENSE("GPL");