// SPDX-License-Identifier: GPL-2.0-or-later

  /*
   * Copyright (C) 2015 Zodiac Inflight Innovations
   *
   * Author: Martyn Welch <martyn.welch@collabora.co.uk>
   *
   * Based on twl4030_wdt.c by Timo Kokkonen <timo.t.kokkonen at nokia.com>:
   *
   * Copyright (C) Nokia Corporation

   */

  #include <linux/delay.h>

  #include <linux/i2c.h>

  #include <linux/ihex.h>
  #include <linux/firmware.h>

  #include <linux/kernel.h>
  #include <linux/module.h>
  #include <linux/slab.h>
  #include <linux/sysfs.h>
  #include <linux/types.h>
  #include <linux/version.h>
  #include <linux/watchdog.h>

  #include <asm/unaligned.h>

  #define ZIIRAVE_TIMEOUT_MIN	3
  #define ZIIRAVE_TIMEOUT_MAX	255

  #define ZIIRAVE_TIMEOUT_DEFAULT	30

  
  #define ZIIRAVE_PING_VALUE	0x0
  
  #define ZIIRAVE_STATE_INITIAL	0x0
  #define ZIIRAVE_STATE_OFF	0x1
  #define ZIIRAVE_STATE_ON	0x2

  #define ZIIRAVE_FW_NAME		"ziirave_wdt.fw"

  static char *ziirave_reasons[] = {"power cycle", "hw watchdog", NULL, NULL,

  				  "host request", NULL, "illegal configuration",
  				  "illegal instruction", "illegal trap",
  				  "unknown"};
  
  #define ZIIRAVE_WDT_FIRM_VER_MAJOR	0x1
  #define ZIIRAVE_WDT_BOOT_VER_MAJOR	0x3
  #define ZIIRAVE_WDT_RESET_REASON	0x5
  #define ZIIRAVE_WDT_STATE		0x6
  #define ZIIRAVE_WDT_TIMEOUT		0x7
  #define ZIIRAVE_WDT_TIME_LEFT		0x8
  #define ZIIRAVE_WDT_PING		0x9
  #define ZIIRAVE_WDT_RESET_DURATION	0xa

  #define ZIIRAVE_FIRM_PKT_TOTAL_SIZE	20
  #define ZIIRAVE_FIRM_PKT_DATA_SIZE	16

  #define ZIIRAVE_FIRM_FLASH_MEMORY_START	(2 * 0x1600)
  #define ZIIRAVE_FIRM_FLASH_MEMORY_END	(2 * 0x2bbf)

  #define ZIIRAVE_FIRM_PAGE_SIZE		128

  
  /* Received and ready for next Download packet. */
  #define ZIIRAVE_FIRM_DOWNLOAD_ACK	1

  
  /* Firmware commands */
  #define ZIIRAVE_CMD_DOWNLOAD_START		0x10
  #define ZIIRAVE_CMD_DOWNLOAD_END		0x11
  #define ZIIRAVE_CMD_DOWNLOAD_SET_READ_ADDR	0x12
  #define ZIIRAVE_CMD_DOWNLOAD_READ_BYTE		0x13
  #define ZIIRAVE_CMD_RESET_PROCESSOR		0x0b
  #define ZIIRAVE_CMD_JUMP_TO_BOOTLOADER		0x0c
  #define ZIIRAVE_CMD_DOWNLOAD_PACKET		0x0e

  #define ZIIRAVE_CMD_JUMP_TO_BOOTLOADER_MAGIC	1

  #define ZIIRAVE_CMD_RESET_PROCESSOR_MAGIC	1

  #define ZIIRAVE_FW_VERSION_FMT	"02.%02u.%02u"
  #define ZIIRAVE_BL_VERSION_FMT	"01.%02u.%02u"

  struct ziirave_wdt_rev {
  	unsigned char major;
  	unsigned char minor;
  };
  
  struct ziirave_wdt_data {

  	struct mutex sysfs_mutex;

  	struct watchdog_device wdd;
  	struct ziirave_wdt_rev bootloader_rev;
  	struct ziirave_wdt_rev firmware_rev;
  	int reset_reason;
  };
  
  static int wdt_timeout;
  module_param(wdt_timeout, int, 0);
  MODULE_PARM_DESC(wdt_timeout, "Watchdog timeout in seconds");
  
  static int reset_duration;
  module_param(reset_duration, int, 0);
  MODULE_PARM_DESC(reset_duration,
  		 "Watchdog reset pulse duration in milliseconds");
  
  static bool nowayout = WATCHDOG_NOWAYOUT;
  module_param(nowayout, bool, 0);
  MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started default="
  		 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
  
  static int ziirave_wdt_revision(struct i2c_client *client,
  				struct ziirave_wdt_rev *rev, u8 command)
  {
  	int ret;
  
  	ret = i2c_smbus_read_byte_data(client, command);
  	if (ret < 0)
  		return ret;
  
  	rev->major = ret;
  
  	ret = i2c_smbus_read_byte_data(client, command + 1);
  	if (ret < 0)
  		return ret;
  
  	rev->minor = ret;
  
  	return 0;
  }
  
  static int ziirave_wdt_set_state(struct watchdog_device *wdd, int state)
  {
  	struct i2c_client *client = to_i2c_client(wdd->parent);
  
  	return i2c_smbus_write_byte_data(client, ZIIRAVE_WDT_STATE, state);
  }
  
  static int ziirave_wdt_start(struct watchdog_device *wdd)
  {
  	return ziirave_wdt_set_state(wdd, ZIIRAVE_STATE_ON);
  }
  
  static int ziirave_wdt_stop(struct watchdog_device *wdd)
  {
  	return ziirave_wdt_set_state(wdd, ZIIRAVE_STATE_OFF);
  }
  
  static int ziirave_wdt_ping(struct watchdog_device *wdd)
  {
  	struct i2c_client *client = to_i2c_client(wdd->parent);
  
  	return i2c_smbus_write_byte_data(client, ZIIRAVE_WDT_PING,
  					 ZIIRAVE_PING_VALUE);
  }
  
  static int ziirave_wdt_set_timeout(struct watchdog_device *wdd,
  				   unsigned int timeout)
  {
  	struct i2c_client *client = to_i2c_client(wdd->parent);
  	int ret;
  
  	ret = i2c_smbus_write_byte_data(client, ZIIRAVE_WDT_TIMEOUT, timeout);
  	if (!ret)
  		wdd->timeout = timeout;
  
  	return ret;
  }
  
  static unsigned int ziirave_wdt_get_timeleft(struct watchdog_device *wdd)
  {
  	struct i2c_client *client = to_i2c_client(wdd->parent);
  	int ret;
  
  	ret = i2c_smbus_read_byte_data(client, ZIIRAVE_WDT_TIME_LEFT);
  	if (ret < 0)
  		ret = 0;
  
  	return ret;
  }

  static int ziirave_firm_read_ack(struct watchdog_device *wdd)

  {
  	struct i2c_client *client = to_i2c_client(wdd->parent);
  	int ret;

  	ret = i2c_smbus_read_byte(client);
  	if (ret < 0) {
  		dev_err(&client->dev, "Failed to read status byte
  ");
  		return ret;
  	}

  
  	return ret == ZIIRAVE_FIRM_DOWNLOAD_ACK ? 0 : -EIO;
  }

  static int ziirave_firm_set_read_addr(struct watchdog_device *wdd, u32 addr)

  {
  	struct i2c_client *client = to_i2c_client(wdd->parent);

  	const u16 addr16 = (u16)addr / 2;

  	u8 address[2];

  	put_unaligned_le16(addr16, address);

  
  	return i2c_smbus_write_block_data(client,
  					  ZIIRAVE_CMD_DOWNLOAD_SET_READ_ADDR,

  					  sizeof(address), address);

  }

  static bool ziirave_firm_addr_readonly(u32 addr)
  {
  	return addr < ZIIRAVE_FIRM_FLASH_MEMORY_START ||
  	       addr > ZIIRAVE_FIRM_FLASH_MEMORY_END;
  }

  /*
   * ziirave_firm_write_pkt() - Build and write a firmware packet
   *
   * A packet to send to the firmware is composed by following bytes:
   *     Length | Addr0 | Addr1 | Data0 .. Data15 | Checksum |
   * Where,
   *     Length: A data byte containing the length of the data.
   *     Addr0: Low byte of the address.
   *     Addr1: High byte of the address.
   *     Data0 .. Data15: Array of 16 bytes of data.
   *     Checksum: Checksum byte to verify data integrity.
   */

  static int __ziirave_firm_write_pkt(struct watchdog_device *wdd,
  				    u32 addr, const u8 *data, u8 len)

  {

  	const u16 addr16 = (u16)addr / 2;

  	struct i2c_client *client = to_i2c_client(wdd->parent);
  	u8 i, checksum = 0, packet[ZIIRAVE_FIRM_PKT_TOTAL_SIZE];
  	int ret;

  	/* Check max data size */
  	if (len > ZIIRAVE_FIRM_PKT_DATA_SIZE) {
  		dev_err(&client->dev, "Firmware packet too long (%d)
  ",
  			len);
  		return -EMSGSIZE;
  	}

  	/*
  	 * Ignore packets that are targeting program memory outisde of
  	 * app partition, since they will be ignored by the
  	 * bootloader. At the same time, we need to make sure we'll
  	 * allow zero length packet that will be sent as the last step
  	 * of firmware update
  	 */
  	if (len && ziirave_firm_addr_readonly(addr))
  		return 0;

  	/* Packet length */

  	packet[0] = len;

  	/* Packet address */

  	put_unaligned_le16(addr16, packet + 1);

  	memcpy(packet + 3, data, len);

  	memset(packet + 3 + len, 0, ZIIRAVE_FIRM_PKT_DATA_SIZE - len);

  
  	/* Packet checksum */

  	for (i = 0; i < len + 3; i++)

  		checksum += packet[i];
  	packet[ZIIRAVE_FIRM_PKT_TOTAL_SIZE - 1] = checksum;

  	ret = i2c_smbus_write_block_data(client, ZIIRAVE_CMD_DOWNLOAD_PACKET,
  					 sizeof(packet), packet);
  	if (ret) {
  		dev_err(&client->dev,
  			"Failed to send DOWNLOAD_PACKET: %d
  ", ret);
  		return ret;
  	}
  
  	ret = ziirave_firm_read_ack(wdd);

  	if (ret)
  		dev_err(&client->dev,
  		      "Failed to write firmware packet at address 0x%04x: %d
  ",

  		      addr, ret);

  
  	return ret;
  }

  static int ziirave_firm_write_pkt(struct watchdog_device *wdd,
  				  u32 addr, const u8 *data, u8 len)
  {
  	const u8 max_write_len = ZIIRAVE_FIRM_PAGE_SIZE -
  		(addr - ALIGN_DOWN(addr, ZIIRAVE_FIRM_PAGE_SIZE));
  	int ret;
  
  	if (len > max_write_len) {
  		/*
  		 * If data crossed page boundary we need to split this
  		 * write in two
  		 */
  		ret = __ziirave_firm_write_pkt(wdd, addr, data, max_write_len);
  		if (ret)
  			return ret;
  
  		addr += max_write_len;
  		data += max_write_len;
  		len  -= max_write_len;
  	}
  
  	return __ziirave_firm_write_pkt(wdd, addr, data, len);
  }

  static int ziirave_firm_verify(struct watchdog_device *wdd,
  			       const struct firmware *fw)
  {
  	struct i2c_client *client = to_i2c_client(wdd->parent);
  	const struct ihex_binrec *rec;
  	int i, ret;
  	u8 data[ZIIRAVE_FIRM_PKT_DATA_SIZE];

  
  	for (rec = (void *)fw->data; rec; rec = ihex_next_binrec(rec)) {

  		const u16 len = be16_to_cpu(rec->len);

  		const u32 addr = be32_to_cpu(rec->addr);

  		if (ziirave_firm_addr_readonly(addr))

  			continue;
  
  		ret = ziirave_firm_set_read_addr(wdd, addr);
  		if (ret) {
  			dev_err(&client->dev,
  				"Failed to send SET_READ_ADDR command: %d
  ",
  				ret);
  			return ret;
  		}

  		for (i = 0; i < len; i++) {

  			ret = i2c_smbus_read_byte_data(client,
  						ZIIRAVE_CMD_DOWNLOAD_READ_BYTE);
  			if (ret < 0) {
  				dev_err(&client->dev,
  					"Failed to READ DATA: %d
  ", ret);
  				return ret;
  			}
  			data[i] = ret;
  		}

  		if (memcmp(data, rec->data, len)) {

  			dev_err(&client->dev,
  				"Firmware mismatch at address 0x%04x
  ", addr);
  			return -EINVAL;
  		}
  	}
  
  	return 0;
  }
  
  static int ziirave_firm_upload(struct watchdog_device *wdd,
  			       const struct firmware *fw)
  {
  	struct i2c_client *client = to_i2c_client(wdd->parent);

  	const struct ihex_binrec *rec;

  	int ret;

  	ret = i2c_smbus_write_byte_data(client,
  					ZIIRAVE_CMD_JUMP_TO_BOOTLOADER,
  					ZIIRAVE_CMD_JUMP_TO_BOOTLOADER_MAGIC);

  	if (ret) {
  		dev_err(&client->dev, "Failed to jump to bootloader
  ");

  		return ret;

  	}

  
  	msleep(500);

  	ret = i2c_smbus_write_byte(client, ZIIRAVE_CMD_DOWNLOAD_START);

  	if (ret) {
  		dev_err(&client->dev, "Failed to start download
  ");

  		return ret;

  	}

  	ret = ziirave_firm_read_ack(wdd);
  	if (ret) {
  		dev_err(&client->dev, "No ACK for start download
  ");
  		return ret;
  	}

  	msleep(500);
  
  	for (rec = (void *)fw->data; rec; rec = ihex_next_binrec(rec)) {

  		ret = ziirave_firm_write_pkt(wdd, be32_to_cpu(rec->addr),
  					     rec->data, be16_to_cpu(rec->len));
  		if (ret)
  			return ret;

  	}

  	/*
  	 * Finish firmware download process by sending a zero length
  	 * payload
  	 */
  	ret = ziirave_firm_write_pkt(wdd, 0, NULL, 0);

  	if (ret) {
  		dev_err(&client->dev, "Failed to send EMPTY packet: %d
  ", ret);
  		return ret;
  	}
  
  	/* This sleep seems to be required */
  	msleep(20);
  
  	/* Start firmware verification */
  	ret = ziirave_firm_verify(wdd, fw);
  	if (ret) {
  		dev_err(&client->dev,
  			"Failed to verify firmware: %d
  ", ret);
  		return ret;
  	}
  
  	/* End download operation */

  	ret = i2c_smbus_write_byte(client, ZIIRAVE_CMD_DOWNLOAD_END);

  	if (ret) {
  		dev_err(&client->dev,
  			"Failed to end firmware download: %d
  ", ret);

  		return ret;

  	}

  
  	/* Reset the processor */

  	ret = i2c_smbus_write_byte_data(client,
  					ZIIRAVE_CMD_RESET_PROCESSOR,
  					ZIIRAVE_CMD_RESET_PROCESSOR_MAGIC);

  	if (ret) {
  		dev_err(&client->dev,
  			"Failed to reset the watchdog: %d
  ", ret);

  		return ret;

  	}

  
  	msleep(500);
  
  	return 0;
  }

  static const struct watchdog_info ziirave_wdt_info = {
  	.options = WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE | WDIOF_KEEPALIVEPING,
  	.identity = "Zodiac RAVE Watchdog",
  };
  
  static const struct watchdog_ops ziirave_wdt_ops = {
  	.owner		= THIS_MODULE,
  	.start		= ziirave_wdt_start,
  	.stop		= ziirave_wdt_stop,
  	.ping		= ziirave_wdt_ping,
  	.set_timeout	= ziirave_wdt_set_timeout,
  	.get_timeleft	= ziirave_wdt_get_timeleft,
  };
  
  static ssize_t ziirave_wdt_sysfs_show_firm(struct device *dev,
  					   struct device_attribute *attr,
  					   char *buf)
  {
  	struct i2c_client *client = to_i2c_client(dev->parent);
  	struct ziirave_wdt_data *w_priv = i2c_get_clientdata(client);

  	int ret;
  
  	ret = mutex_lock_interruptible(&w_priv->sysfs_mutex);
  	if (ret)
  		return ret;

  	ret = sprintf(buf, ZIIRAVE_FW_VERSION_FMT, w_priv->firmware_rev.major,

  		      w_priv->firmware_rev.minor);
  
  	mutex_unlock(&w_priv->sysfs_mutex);

  	return ret;

  }
  
  static DEVICE_ATTR(firmware_version, S_IRUGO, ziirave_wdt_sysfs_show_firm,
  		   NULL);
  
  static ssize_t ziirave_wdt_sysfs_show_boot(struct device *dev,
  					   struct device_attribute *attr,
  					   char *buf)
  {
  	struct i2c_client *client = to_i2c_client(dev->parent);
  	struct ziirave_wdt_data *w_priv = i2c_get_clientdata(client);

  	int ret;
  
  	ret = mutex_lock_interruptible(&w_priv->sysfs_mutex);
  	if (ret)
  		return ret;

  	ret = sprintf(buf, ZIIRAVE_BL_VERSION_FMT, w_priv->bootloader_rev.major,

  		      w_priv->bootloader_rev.minor);
  
  	mutex_unlock(&w_priv->sysfs_mutex);
  
  	return ret;

  }
  
  static DEVICE_ATTR(bootloader_version, S_IRUGO, ziirave_wdt_sysfs_show_boot,
  		   NULL);
  
  static ssize_t ziirave_wdt_sysfs_show_reason(struct device *dev,
  					     struct device_attribute *attr,
  					     char *buf)
  {
  	struct i2c_client *client = to_i2c_client(dev->parent);
  	struct ziirave_wdt_data *w_priv = i2c_get_clientdata(client);

  	int ret;

  	ret = mutex_lock_interruptible(&w_priv->sysfs_mutex);
  	if (ret)
  		return ret;
  
  	ret = sprintf(buf, "%s", ziirave_reasons[w_priv->reset_reason]);
  
  	mutex_unlock(&w_priv->sysfs_mutex);
  
  	return ret;

  }
  
  static DEVICE_ATTR(reset_reason, S_IRUGO, ziirave_wdt_sysfs_show_reason,
  		   NULL);

  static ssize_t ziirave_wdt_sysfs_store_firm(struct device *dev,
  					    struct device_attribute *attr,
  					    const char *buf, size_t count)
  {
  	struct i2c_client *client = to_i2c_client(dev->parent);
  	struct ziirave_wdt_data *w_priv = i2c_get_clientdata(client);
  	const struct firmware *fw;
  	int err;
  
  	err = request_ihex_firmware(&fw, ZIIRAVE_FW_NAME, dev);
  	if (err) {
  		dev_err(&client->dev, "Failed to request ihex firmware
  ");
  		return err;
  	}
  
  	err = mutex_lock_interruptible(&w_priv->sysfs_mutex);
  	if (err)
  		goto release_firmware;
  
  	err = ziirave_firm_upload(&w_priv->wdd, fw);
  	if (err) {
  		dev_err(&client->dev, "The firmware update failed: %d
  ", err);
  		goto unlock_mutex;
  	}
  
  	/* Update firmware version */
  	err = ziirave_wdt_revision(client, &w_priv->firmware_rev,
  				   ZIIRAVE_WDT_FIRM_VER_MAJOR);
  	if (err) {
  		dev_err(&client->dev, "Failed to read firmware version: %d
  ",
  			err);
  		goto unlock_mutex;
  	}

  	dev_info(&client->dev,
  		 "Firmware updated to version " ZIIRAVE_FW_VERSION_FMT "
  ",

  		 w_priv->firmware_rev.major, w_priv->firmware_rev.minor);
  
  	/* Restore the watchdog timeout */
  	err = ziirave_wdt_set_timeout(&w_priv->wdd, w_priv->wdd.timeout);
  	if (err)
  		dev_err(&client->dev, "Failed to set timeout: %d
  ", err);
  
  unlock_mutex:
  	mutex_unlock(&w_priv->sysfs_mutex);
  
  release_firmware:
  	release_firmware(fw);
  
  	return err ? err : count;
  }
  
  static DEVICE_ATTR(update_firmware, S_IWUSR, NULL,
  		   ziirave_wdt_sysfs_store_firm);

  static struct attribute *ziirave_wdt_attrs[] = {
  	&dev_attr_firmware_version.attr,
  	&dev_attr_bootloader_version.attr,
  	&dev_attr_reset_reason.attr,

  	&dev_attr_update_firmware.attr,

  	NULL
  };

  ATTRIBUTE_GROUPS(ziirave_wdt);

  
  static int ziirave_wdt_init_duration(struct i2c_client *client)
  {
  	int ret;
  
  	if (!reset_duration) {
  		/* See if the reset pulse duration is provided in an of_node */
  		if (!client->dev.of_node)
  			ret = -ENODEV;
  		else
  			ret = of_property_read_u32(client->dev.of_node,
  						   "reset-duration-ms",
  						   &reset_duration);
  		if (ret) {
  			dev_info(&client->dev,

  			 "No reset pulse duration specified, using default
  ");

  			return 0;
  		}
  	}
  
  	if (reset_duration < 1 || reset_duration > 255)
  		return -EINVAL;
  
  	dev_info(&client->dev, "Setting reset duration to %dms",
  		 reset_duration);
  
  	return i2c_smbus_write_byte_data(client, ZIIRAVE_WDT_RESET_DURATION,
  					 reset_duration);
  }
  
  static int ziirave_wdt_probe(struct i2c_client *client,
  			     const struct i2c_device_id *id)
  {
  	int ret;
  	struct ziirave_wdt_data *w_priv;
  	int val;

  	if (!i2c_check_functionality(client->adapter,
  				     I2C_FUNC_SMBUS_BYTE |
  				     I2C_FUNC_SMBUS_BYTE_DATA |
  				     I2C_FUNC_SMBUS_WRITE_BLOCK_DATA))

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

  	mutex_init(&w_priv->sysfs_mutex);

  	w_priv->wdd.info = &ziirave_wdt_info;
  	w_priv->wdd.ops = &ziirave_wdt_ops;
  	w_priv->wdd.min_timeout = ZIIRAVE_TIMEOUT_MIN;
  	w_priv->wdd.max_timeout = ZIIRAVE_TIMEOUT_MAX;
  	w_priv->wdd.parent = &client->dev;

  	w_priv->wdd.groups = ziirave_wdt_groups;

  	watchdog_init_timeout(&w_priv->wdd, wdt_timeout, &client->dev);

  
  	/*
  	 * The default value set in the watchdog should be perfectly valid, so
  	 * pass that in if we haven't provided one via the module parameter or
  	 * of property.
  	 */
  	if (w_priv->wdd.timeout == 0) {
  		val = i2c_smbus_read_byte_data(client, ZIIRAVE_WDT_TIMEOUT);

  		if (val < 0) {
  			dev_err(&client->dev, "Failed to read timeout
  ");

  			return val;

  		}

  		if (val > ZIIRAVE_TIMEOUT_MAX ||
  		    val < ZIIRAVE_TIMEOUT_MIN)
  			val = ZIIRAVE_TIMEOUT_DEFAULT;

  
  		w_priv->wdd.timeout = val;

  	}

  	ret = ziirave_wdt_set_timeout(&w_priv->wdd, w_priv->wdd.timeout);
  	if (ret) {
  		dev_err(&client->dev, "Failed to set timeout
  ");
  		return ret;

  	}

  	dev_info(&client->dev, "Timeout set to %ds
  ", w_priv->wdd.timeout);

  	watchdog_set_nowayout(&w_priv->wdd, nowayout);
  
  	i2c_set_clientdata(client, w_priv);
  
  	/* If in unconfigured state, set to stopped */
  	val = i2c_smbus_read_byte_data(client, ZIIRAVE_WDT_STATE);

  	if (val < 0) {
  		dev_err(&client->dev, "Failed to read state
  ");

  		return val;

  	}

  
  	if (val == ZIIRAVE_STATE_INITIAL)
  		ziirave_wdt_stop(&w_priv->wdd);
  
  	ret = ziirave_wdt_init_duration(client);

  	if (ret) {
  		dev_err(&client->dev, "Failed to init duration
  ");

  		return ret;

  	}

  
  	ret = ziirave_wdt_revision(client, &w_priv->firmware_rev,
  				   ZIIRAVE_WDT_FIRM_VER_MAJOR);

  	if (ret) {
  		dev_err(&client->dev, "Failed to read firmware version
  ");

  		return ret;

  	}

  	dev_info(&client->dev,
  		 "Firmware version: " ZIIRAVE_FW_VERSION_FMT "
  ",
  		 w_priv->firmware_rev.major, w_priv->firmware_rev.minor);

  	ret = ziirave_wdt_revision(client, &w_priv->bootloader_rev,
  				   ZIIRAVE_WDT_BOOT_VER_MAJOR);

  	if (ret) {
  		dev_err(&client->dev, "Failed to read bootloader version
  ");

  		return ret;

  	}

  	dev_info(&client->dev,
  		 "Bootloader version: " ZIIRAVE_BL_VERSION_FMT "
  ",
  		 w_priv->bootloader_rev.major, w_priv->bootloader_rev.minor);

  	w_priv->reset_reason = i2c_smbus_read_byte_data(client,
  						ZIIRAVE_WDT_RESET_REASON);

  	if (w_priv->reset_reason < 0) {
  		dev_err(&client->dev, "Failed to read reset reason
  ");

  		return w_priv->reset_reason;

  	}

  
  	if (w_priv->reset_reason >= ARRAY_SIZE(ziirave_reasons) ||

  	    !ziirave_reasons[w_priv->reset_reason]) {
  		dev_err(&client->dev, "Invalid reset reason
  ");

  		return -ENODEV;

  	}

  
  	ret = watchdog_register_device(&w_priv->wdd);

  	return ret;

  }
  
  static int ziirave_wdt_remove(struct i2c_client *client)
  {
  	struct ziirave_wdt_data *w_priv = i2c_get_clientdata(client);

  	watchdog_unregister_device(&w_priv->wdd);
  
  	return 0;
  }

  static const struct i2c_device_id ziirave_wdt_id[] = {

  	{ "rave-wdt", 0 },

  	{ }
  };
  MODULE_DEVICE_TABLE(i2c, ziirave_wdt_id);
  
  static const struct of_device_id zrv_wdt_of_match[] = {
  	{ .compatible = "zii,rave-wdt", },
  	{ },
  };
  MODULE_DEVICE_TABLE(of, zrv_wdt_of_match);
  
  static struct i2c_driver ziirave_wdt_driver = {
  	.driver = {
  		.name = "ziirave_wdt",
  		.of_match_table = zrv_wdt_of_match,
  	},
  	.probe = ziirave_wdt_probe,
  	.remove = ziirave_wdt_remove,
  	.id_table = ziirave_wdt_id,
  };
  
  module_i2c_driver(ziirave_wdt_driver);
  
  MODULE_AUTHOR("Martyn Welch <martyn.welch@collabora.co.uk");
  MODULE_DESCRIPTION("Zodiac Aerospace RAVE Switch Watchdog Processor Driver");
  MODULE_LICENSE("GPL");