cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
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ziirave_wdt.c (18874B)


      1// SPDX-License-Identifier: GPL-2.0-or-later
      2/*
      3 * Copyright (C) 2015 Zodiac Inflight Innovations
      4 *
      5 * Author: Martyn Welch <martyn.welch@collabora.co.uk>
      6 *
      7 * Based on twl4030_wdt.c by Timo Kokkonen <timo.t.kokkonen at nokia.com>:
      8 *
      9 * Copyright (C) Nokia Corporation
     10 */
     11
     12#include <linux/delay.h>
     13#include <linux/i2c.h>
     14#include <linux/ihex.h>
     15#include <linux/firmware.h>
     16#include <linux/kernel.h>
     17#include <linux/module.h>
     18#include <linux/slab.h>
     19#include <linux/sysfs.h>
     20#include <linux/types.h>
     21#include <linux/watchdog.h>
     22
     23#include <asm/unaligned.h>
     24
     25#define ZIIRAVE_TIMEOUT_MIN	3
     26#define ZIIRAVE_TIMEOUT_MAX	255
     27#define ZIIRAVE_TIMEOUT_DEFAULT	30
     28
     29#define ZIIRAVE_PING_VALUE	0x0
     30
     31#define ZIIRAVE_STATE_INITIAL	0x0
     32#define ZIIRAVE_STATE_OFF	0x1
     33#define ZIIRAVE_STATE_ON	0x2
     34
     35#define ZIIRAVE_FW_NAME		"ziirave_wdt.fw"
     36
     37static char *ziirave_reasons[] = {"power cycle", "hw watchdog", NULL, NULL,
     38				  "host request", NULL, "illegal configuration",
     39				  "illegal instruction", "illegal trap",
     40				  "unknown"};
     41
     42#define ZIIRAVE_WDT_FIRM_VER_MAJOR	0x1
     43#define ZIIRAVE_WDT_BOOT_VER_MAJOR	0x3
     44#define ZIIRAVE_WDT_RESET_REASON	0x5
     45#define ZIIRAVE_WDT_STATE		0x6
     46#define ZIIRAVE_WDT_TIMEOUT		0x7
     47#define ZIIRAVE_WDT_TIME_LEFT		0x8
     48#define ZIIRAVE_WDT_PING		0x9
     49#define ZIIRAVE_WDT_RESET_DURATION	0xa
     50
     51#define ZIIRAVE_FIRM_PKT_TOTAL_SIZE	20
     52#define ZIIRAVE_FIRM_PKT_DATA_SIZE	16
     53#define ZIIRAVE_FIRM_FLASH_MEMORY_START	(2 * 0x1600)
     54#define ZIIRAVE_FIRM_FLASH_MEMORY_END	(2 * 0x2bbf)
     55#define ZIIRAVE_FIRM_PAGE_SIZE		128
     56
     57/* Received and ready for next Download packet. */
     58#define ZIIRAVE_FIRM_DOWNLOAD_ACK	1
     59
     60/* Firmware commands */
     61#define ZIIRAVE_CMD_DOWNLOAD_START		0x10
     62#define ZIIRAVE_CMD_DOWNLOAD_END		0x11
     63#define ZIIRAVE_CMD_DOWNLOAD_SET_READ_ADDR	0x12
     64#define ZIIRAVE_CMD_DOWNLOAD_READ_BYTE		0x13
     65#define ZIIRAVE_CMD_RESET_PROCESSOR		0x0b
     66#define ZIIRAVE_CMD_JUMP_TO_BOOTLOADER		0x0c
     67#define ZIIRAVE_CMD_DOWNLOAD_PACKET		0x0e
     68
     69#define ZIIRAVE_CMD_JUMP_TO_BOOTLOADER_MAGIC	1
     70#define ZIIRAVE_CMD_RESET_PROCESSOR_MAGIC	1
     71
     72struct ziirave_wdt_rev {
     73	unsigned char major;
     74	unsigned char minor;
     75};
     76
     77struct ziirave_wdt_data {
     78	struct mutex sysfs_mutex;
     79	struct watchdog_device wdd;
     80	struct ziirave_wdt_rev bootloader_rev;
     81	struct ziirave_wdt_rev firmware_rev;
     82	int reset_reason;
     83};
     84
     85static int wdt_timeout;
     86module_param(wdt_timeout, int, 0);
     87MODULE_PARM_DESC(wdt_timeout, "Watchdog timeout in seconds");
     88
     89static int reset_duration;
     90module_param(reset_duration, int, 0);
     91MODULE_PARM_DESC(reset_duration,
     92		 "Watchdog reset pulse duration in milliseconds");
     93
     94static bool nowayout = WATCHDOG_NOWAYOUT;
     95module_param(nowayout, bool, 0);
     96MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started default="
     97		 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
     98
     99static int ziirave_wdt_revision(struct i2c_client *client,
    100				struct ziirave_wdt_rev *rev, u8 command)
    101{
    102	int ret;
    103
    104	ret = i2c_smbus_read_byte_data(client, command);
    105	if (ret < 0)
    106		return ret;
    107
    108	rev->major = ret;
    109
    110	ret = i2c_smbus_read_byte_data(client, command + 1);
    111	if (ret < 0)
    112		return ret;
    113
    114	rev->minor = ret;
    115
    116	return 0;
    117}
    118
    119static int ziirave_wdt_set_state(struct watchdog_device *wdd, int state)
    120{
    121	struct i2c_client *client = to_i2c_client(wdd->parent);
    122
    123	return i2c_smbus_write_byte_data(client, ZIIRAVE_WDT_STATE, state);
    124}
    125
    126static int ziirave_wdt_start(struct watchdog_device *wdd)
    127{
    128	return ziirave_wdt_set_state(wdd, ZIIRAVE_STATE_ON);
    129}
    130
    131static int ziirave_wdt_stop(struct watchdog_device *wdd)
    132{
    133	return ziirave_wdt_set_state(wdd, ZIIRAVE_STATE_OFF);
    134}
    135
    136static int ziirave_wdt_ping(struct watchdog_device *wdd)
    137{
    138	struct i2c_client *client = to_i2c_client(wdd->parent);
    139
    140	return i2c_smbus_write_byte_data(client, ZIIRAVE_WDT_PING,
    141					 ZIIRAVE_PING_VALUE);
    142}
    143
    144static int ziirave_wdt_set_timeout(struct watchdog_device *wdd,
    145				   unsigned int timeout)
    146{
    147	struct i2c_client *client = to_i2c_client(wdd->parent);
    148	int ret;
    149
    150	ret = i2c_smbus_write_byte_data(client, ZIIRAVE_WDT_TIMEOUT, timeout);
    151	if (!ret)
    152		wdd->timeout = timeout;
    153
    154	return ret;
    155}
    156
    157static unsigned int ziirave_wdt_get_timeleft(struct watchdog_device *wdd)
    158{
    159	struct i2c_client *client = to_i2c_client(wdd->parent);
    160	int ret;
    161
    162	ret = i2c_smbus_read_byte_data(client, ZIIRAVE_WDT_TIME_LEFT);
    163	if (ret < 0)
    164		ret = 0;
    165
    166	return ret;
    167}
    168
    169static int ziirave_firm_read_ack(struct watchdog_device *wdd)
    170{
    171	struct i2c_client *client = to_i2c_client(wdd->parent);
    172	int ret;
    173
    174	ret = i2c_smbus_read_byte(client);
    175	if (ret < 0) {
    176		dev_err(&client->dev, "Failed to read status byte\n");
    177		return ret;
    178	}
    179
    180	return ret == ZIIRAVE_FIRM_DOWNLOAD_ACK ? 0 : -EIO;
    181}
    182
    183static int ziirave_firm_set_read_addr(struct watchdog_device *wdd, u32 addr)
    184{
    185	struct i2c_client *client = to_i2c_client(wdd->parent);
    186	const u16 addr16 = (u16)addr / 2;
    187	u8 address[2];
    188
    189	put_unaligned_le16(addr16, address);
    190
    191	return i2c_smbus_write_block_data(client,
    192					  ZIIRAVE_CMD_DOWNLOAD_SET_READ_ADDR,
    193					  sizeof(address), address);
    194}
    195
    196static bool ziirave_firm_addr_readonly(u32 addr)
    197{
    198	return addr < ZIIRAVE_FIRM_FLASH_MEMORY_START ||
    199	       addr > ZIIRAVE_FIRM_FLASH_MEMORY_END;
    200}
    201
    202/*
    203 * ziirave_firm_write_pkt() - Build and write a firmware packet
    204 *
    205 * A packet to send to the firmware is composed by following bytes:
    206 *     Length | Addr0 | Addr1 | Data0 .. Data15 | Checksum |
    207 * Where,
    208 *     Length: A data byte containing the length of the data.
    209 *     Addr0: Low byte of the address.
    210 *     Addr1: High byte of the address.
    211 *     Data0 .. Data15: Array of 16 bytes of data.
    212 *     Checksum: Checksum byte to verify data integrity.
    213 */
    214static int __ziirave_firm_write_pkt(struct watchdog_device *wdd,
    215				    u32 addr, const u8 *data, u8 len)
    216{
    217	const u16 addr16 = (u16)addr / 2;
    218	struct i2c_client *client = to_i2c_client(wdd->parent);
    219	u8 i, checksum = 0, packet[ZIIRAVE_FIRM_PKT_TOTAL_SIZE];
    220	int ret;
    221
    222	/* Check max data size */
    223	if (len > ZIIRAVE_FIRM_PKT_DATA_SIZE) {
    224		dev_err(&client->dev, "Firmware packet too long (%d)\n",
    225			len);
    226		return -EMSGSIZE;
    227	}
    228
    229	/*
    230	 * Ignore packets that are targeting program memory outisde of
    231	 * app partition, since they will be ignored by the
    232	 * bootloader. At the same time, we need to make sure we'll
    233	 * allow zero length packet that will be sent as the last step
    234	 * of firmware update
    235	 */
    236	if (len && ziirave_firm_addr_readonly(addr))
    237		return 0;
    238
    239	/* Packet length */
    240	packet[0] = len;
    241	/* Packet address */
    242	put_unaligned_le16(addr16, packet + 1);
    243
    244	memcpy(packet + 3, data, len);
    245	memset(packet + 3 + len, 0, ZIIRAVE_FIRM_PKT_DATA_SIZE - len);
    246
    247	/* Packet checksum */
    248	for (i = 0; i < len + 3; i++)
    249		checksum += packet[i];
    250	packet[ZIIRAVE_FIRM_PKT_TOTAL_SIZE - 1] = checksum;
    251
    252	ret = i2c_smbus_write_block_data(client, ZIIRAVE_CMD_DOWNLOAD_PACKET,
    253					 sizeof(packet), packet);
    254	if (ret) {
    255		dev_err(&client->dev,
    256			"Failed to send DOWNLOAD_PACKET: %d\n", ret);
    257		return ret;
    258	}
    259
    260	ret = ziirave_firm_read_ack(wdd);
    261	if (ret)
    262		dev_err(&client->dev,
    263		      "Failed to write firmware packet at address 0x%04x: %d\n",
    264		      addr, ret);
    265
    266	return ret;
    267}
    268
    269static int ziirave_firm_write_pkt(struct watchdog_device *wdd,
    270				  u32 addr, const u8 *data, u8 len)
    271{
    272	const u8 max_write_len = ZIIRAVE_FIRM_PAGE_SIZE -
    273		(addr - ALIGN_DOWN(addr, ZIIRAVE_FIRM_PAGE_SIZE));
    274	int ret;
    275
    276	if (len > max_write_len) {
    277		/*
    278		 * If data crossed page boundary we need to split this
    279		 * write in two
    280		 */
    281		ret = __ziirave_firm_write_pkt(wdd, addr, data, max_write_len);
    282		if (ret)
    283			return ret;
    284
    285		addr += max_write_len;
    286		data += max_write_len;
    287		len  -= max_write_len;
    288	}
    289
    290	return __ziirave_firm_write_pkt(wdd, addr, data, len);
    291}
    292
    293static int ziirave_firm_verify(struct watchdog_device *wdd,
    294			       const struct firmware *fw)
    295{
    296	struct i2c_client *client = to_i2c_client(wdd->parent);
    297	const struct ihex_binrec *rec;
    298	int i, ret;
    299	u8 data[ZIIRAVE_FIRM_PKT_DATA_SIZE];
    300
    301	for (rec = (void *)fw->data; rec; rec = ihex_next_binrec(rec)) {
    302		const u16 len = be16_to_cpu(rec->len);
    303		const u32 addr = be32_to_cpu(rec->addr);
    304
    305		if (ziirave_firm_addr_readonly(addr))
    306			continue;
    307
    308		ret = ziirave_firm_set_read_addr(wdd, addr);
    309		if (ret) {
    310			dev_err(&client->dev,
    311				"Failed to send SET_READ_ADDR command: %d\n",
    312				ret);
    313			return ret;
    314		}
    315
    316		for (i = 0; i < len; i++) {
    317			ret = i2c_smbus_read_byte_data(client,
    318						ZIIRAVE_CMD_DOWNLOAD_READ_BYTE);
    319			if (ret < 0) {
    320				dev_err(&client->dev,
    321					"Failed to READ DATA: %d\n", ret);
    322				return ret;
    323			}
    324			data[i] = ret;
    325		}
    326
    327		if (memcmp(data, rec->data, len)) {
    328			dev_err(&client->dev,
    329				"Firmware mismatch at address 0x%04x\n", addr);
    330			return -EINVAL;
    331		}
    332	}
    333
    334	return 0;
    335}
    336
    337static int ziirave_firm_upload(struct watchdog_device *wdd,
    338			       const struct firmware *fw)
    339{
    340	struct i2c_client *client = to_i2c_client(wdd->parent);
    341	const struct ihex_binrec *rec;
    342	int ret;
    343
    344	ret = i2c_smbus_write_byte_data(client,
    345					ZIIRAVE_CMD_JUMP_TO_BOOTLOADER,
    346					ZIIRAVE_CMD_JUMP_TO_BOOTLOADER_MAGIC);
    347	if (ret) {
    348		dev_err(&client->dev, "Failed to jump to bootloader\n");
    349		return ret;
    350	}
    351
    352	msleep(500);
    353
    354	ret = i2c_smbus_write_byte(client, ZIIRAVE_CMD_DOWNLOAD_START);
    355	if (ret) {
    356		dev_err(&client->dev, "Failed to start download\n");
    357		return ret;
    358	}
    359
    360	ret = ziirave_firm_read_ack(wdd);
    361	if (ret) {
    362		dev_err(&client->dev, "No ACK for start download\n");
    363		return ret;
    364	}
    365
    366	msleep(500);
    367
    368	for (rec = (void *)fw->data; rec; rec = ihex_next_binrec(rec)) {
    369		ret = ziirave_firm_write_pkt(wdd, be32_to_cpu(rec->addr),
    370					     rec->data, be16_to_cpu(rec->len));
    371		if (ret)
    372			return ret;
    373	}
    374
    375	/*
    376	 * Finish firmware download process by sending a zero length
    377	 * payload
    378	 */
    379	ret = ziirave_firm_write_pkt(wdd, 0, NULL, 0);
    380	if (ret) {
    381		dev_err(&client->dev, "Failed to send EMPTY packet: %d\n", ret);
    382		return ret;
    383	}
    384
    385	/* This sleep seems to be required */
    386	msleep(20);
    387
    388	/* Start firmware verification */
    389	ret = ziirave_firm_verify(wdd, fw);
    390	if (ret) {
    391		dev_err(&client->dev,
    392			"Failed to verify firmware: %d\n", ret);
    393		return ret;
    394	}
    395
    396	/* End download operation */
    397	ret = i2c_smbus_write_byte(client, ZIIRAVE_CMD_DOWNLOAD_END);
    398	if (ret) {
    399		dev_err(&client->dev,
    400			"Failed to end firmware download: %d\n", ret);
    401		return ret;
    402	}
    403
    404	/* Reset the processor */
    405	ret = i2c_smbus_write_byte_data(client,
    406					ZIIRAVE_CMD_RESET_PROCESSOR,
    407					ZIIRAVE_CMD_RESET_PROCESSOR_MAGIC);
    408	if (ret) {
    409		dev_err(&client->dev,
    410			"Failed to reset the watchdog: %d\n", ret);
    411		return ret;
    412	}
    413
    414	msleep(500);
    415
    416	return 0;
    417}
    418
    419static const struct watchdog_info ziirave_wdt_info = {
    420	.options = WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE | WDIOF_KEEPALIVEPING,
    421	.identity = "RAVE Switch Watchdog",
    422};
    423
    424static const struct watchdog_ops ziirave_wdt_ops = {
    425	.owner		= THIS_MODULE,
    426	.start		= ziirave_wdt_start,
    427	.stop		= ziirave_wdt_stop,
    428	.ping		= ziirave_wdt_ping,
    429	.set_timeout	= ziirave_wdt_set_timeout,
    430	.get_timeleft	= ziirave_wdt_get_timeleft,
    431};
    432
    433static ssize_t ziirave_wdt_sysfs_show_firm(struct device *dev,
    434					   struct device_attribute *attr,
    435					   char *buf)
    436{
    437	struct i2c_client *client = to_i2c_client(dev->parent);
    438	struct ziirave_wdt_data *w_priv = i2c_get_clientdata(client);
    439	int ret;
    440
    441	ret = mutex_lock_interruptible(&w_priv->sysfs_mutex);
    442	if (ret)
    443		return ret;
    444
    445	ret = sysfs_emit(buf, "02.%02u.%02u\n",
    446			 w_priv->firmware_rev.major,
    447			 w_priv->firmware_rev.minor);
    448
    449	mutex_unlock(&w_priv->sysfs_mutex);
    450
    451	return ret;
    452}
    453
    454static DEVICE_ATTR(firmware_version, S_IRUGO, ziirave_wdt_sysfs_show_firm,
    455		   NULL);
    456
    457static ssize_t ziirave_wdt_sysfs_show_boot(struct device *dev,
    458					   struct device_attribute *attr,
    459					   char *buf)
    460{
    461	struct i2c_client *client = to_i2c_client(dev->parent);
    462	struct ziirave_wdt_data *w_priv = i2c_get_clientdata(client);
    463	int ret;
    464
    465	ret = mutex_lock_interruptible(&w_priv->sysfs_mutex);
    466	if (ret)
    467		return ret;
    468
    469	ret = sysfs_emit(buf, "01.%02u.%02u\n",
    470			 w_priv->bootloader_rev.major,
    471			 w_priv->bootloader_rev.minor);
    472
    473	mutex_unlock(&w_priv->sysfs_mutex);
    474
    475	return ret;
    476}
    477
    478static DEVICE_ATTR(bootloader_version, S_IRUGO, ziirave_wdt_sysfs_show_boot,
    479		   NULL);
    480
    481static ssize_t ziirave_wdt_sysfs_show_reason(struct device *dev,
    482					     struct device_attribute *attr,
    483					     char *buf)
    484{
    485	struct i2c_client *client = to_i2c_client(dev->parent);
    486	struct ziirave_wdt_data *w_priv = i2c_get_clientdata(client);
    487	int ret;
    488
    489	ret = mutex_lock_interruptible(&w_priv->sysfs_mutex);
    490	if (ret)
    491		return ret;
    492
    493	ret = sysfs_emit(buf, "%s\n", ziirave_reasons[w_priv->reset_reason]);
    494
    495	mutex_unlock(&w_priv->sysfs_mutex);
    496
    497	return ret;
    498}
    499
    500static DEVICE_ATTR(reset_reason, S_IRUGO, ziirave_wdt_sysfs_show_reason,
    501		   NULL);
    502
    503static ssize_t ziirave_wdt_sysfs_store_firm(struct device *dev,
    504					    struct device_attribute *attr,
    505					    const char *buf, size_t count)
    506{
    507	struct i2c_client *client = to_i2c_client(dev->parent);
    508	struct ziirave_wdt_data *w_priv = i2c_get_clientdata(client);
    509	const struct firmware *fw;
    510	int err;
    511
    512	err = request_ihex_firmware(&fw, ZIIRAVE_FW_NAME, dev);
    513	if (err) {
    514		dev_err(&client->dev, "Failed to request ihex firmware\n");
    515		return err;
    516	}
    517
    518	err = mutex_lock_interruptible(&w_priv->sysfs_mutex);
    519	if (err)
    520		goto release_firmware;
    521
    522	err = ziirave_firm_upload(&w_priv->wdd, fw);
    523	if (err) {
    524		dev_err(&client->dev, "The firmware update failed: %d\n", err);
    525		goto unlock_mutex;
    526	}
    527
    528	/* Update firmware version */
    529	err = ziirave_wdt_revision(client, &w_priv->firmware_rev,
    530				   ZIIRAVE_WDT_FIRM_VER_MAJOR);
    531	if (err) {
    532		dev_err(&client->dev, "Failed to read firmware version: %d\n",
    533			err);
    534		goto unlock_mutex;
    535	}
    536
    537	dev_info(&client->dev,
    538		 "Firmware updated to version 02.%02u.%02u\n",
    539		 w_priv->firmware_rev.major, w_priv->firmware_rev.minor);
    540
    541	/* Restore the watchdog timeout */
    542	err = ziirave_wdt_set_timeout(&w_priv->wdd, w_priv->wdd.timeout);
    543	if (err)
    544		dev_err(&client->dev, "Failed to set timeout: %d\n", err);
    545
    546unlock_mutex:
    547	mutex_unlock(&w_priv->sysfs_mutex);
    548
    549release_firmware:
    550	release_firmware(fw);
    551
    552	return err ? err : count;
    553}
    554
    555static DEVICE_ATTR(update_firmware, S_IWUSR, NULL,
    556		   ziirave_wdt_sysfs_store_firm);
    557
    558static struct attribute *ziirave_wdt_attrs[] = {
    559	&dev_attr_firmware_version.attr,
    560	&dev_attr_bootloader_version.attr,
    561	&dev_attr_reset_reason.attr,
    562	&dev_attr_update_firmware.attr,
    563	NULL
    564};
    565ATTRIBUTE_GROUPS(ziirave_wdt);
    566
    567static int ziirave_wdt_init_duration(struct i2c_client *client)
    568{
    569	int ret;
    570
    571	if (!reset_duration) {
    572		/* See if the reset pulse duration is provided in an of_node */
    573		if (!client->dev.of_node)
    574			ret = -ENODEV;
    575		else
    576			ret = of_property_read_u32(client->dev.of_node,
    577						   "reset-duration-ms",
    578						   &reset_duration);
    579		if (ret) {
    580			dev_info(&client->dev,
    581			 "No reset pulse duration specified, using default\n");
    582			return 0;
    583		}
    584	}
    585
    586	if (reset_duration < 1 || reset_duration > 255)
    587		return -EINVAL;
    588
    589	dev_info(&client->dev, "Setting reset duration to %dms",
    590		 reset_duration);
    591
    592	return i2c_smbus_write_byte_data(client, ZIIRAVE_WDT_RESET_DURATION,
    593					 reset_duration);
    594}
    595
    596static int ziirave_wdt_probe(struct i2c_client *client,
    597			     const struct i2c_device_id *id)
    598{
    599	int ret;
    600	struct ziirave_wdt_data *w_priv;
    601	int val;
    602
    603	if (!i2c_check_functionality(client->adapter,
    604				     I2C_FUNC_SMBUS_BYTE |
    605				     I2C_FUNC_SMBUS_BYTE_DATA |
    606				     I2C_FUNC_SMBUS_WRITE_BLOCK_DATA))
    607		return -ENODEV;
    608
    609	w_priv = devm_kzalloc(&client->dev, sizeof(*w_priv), GFP_KERNEL);
    610	if (!w_priv)
    611		return -ENOMEM;
    612
    613	mutex_init(&w_priv->sysfs_mutex);
    614
    615	w_priv->wdd.info = &ziirave_wdt_info;
    616	w_priv->wdd.ops = &ziirave_wdt_ops;
    617	w_priv->wdd.min_timeout = ZIIRAVE_TIMEOUT_MIN;
    618	w_priv->wdd.max_timeout = ZIIRAVE_TIMEOUT_MAX;
    619	w_priv->wdd.parent = &client->dev;
    620	w_priv->wdd.groups = ziirave_wdt_groups;
    621
    622	watchdog_init_timeout(&w_priv->wdd, wdt_timeout, &client->dev);
    623
    624	/*
    625	 * The default value set in the watchdog should be perfectly valid, so
    626	 * pass that in if we haven't provided one via the module parameter or
    627	 * of property.
    628	 */
    629	if (w_priv->wdd.timeout == 0) {
    630		val = i2c_smbus_read_byte_data(client, ZIIRAVE_WDT_TIMEOUT);
    631		if (val < 0) {
    632			dev_err(&client->dev, "Failed to read timeout\n");
    633			return val;
    634		}
    635
    636		if (val > ZIIRAVE_TIMEOUT_MAX ||
    637		    val < ZIIRAVE_TIMEOUT_MIN)
    638			val = ZIIRAVE_TIMEOUT_DEFAULT;
    639
    640		w_priv->wdd.timeout = val;
    641	}
    642
    643	ret = ziirave_wdt_set_timeout(&w_priv->wdd, w_priv->wdd.timeout);
    644	if (ret) {
    645		dev_err(&client->dev, "Failed to set timeout\n");
    646		return ret;
    647	}
    648
    649	dev_info(&client->dev, "Timeout set to %ds\n", w_priv->wdd.timeout);
    650
    651	watchdog_set_nowayout(&w_priv->wdd, nowayout);
    652
    653	i2c_set_clientdata(client, w_priv);
    654
    655	/* If in unconfigured state, set to stopped */
    656	val = i2c_smbus_read_byte_data(client, ZIIRAVE_WDT_STATE);
    657	if (val < 0) {
    658		dev_err(&client->dev, "Failed to read state\n");
    659		return val;
    660	}
    661
    662	if (val == ZIIRAVE_STATE_INITIAL)
    663		ziirave_wdt_stop(&w_priv->wdd);
    664
    665	ret = ziirave_wdt_init_duration(client);
    666	if (ret) {
    667		dev_err(&client->dev, "Failed to init duration\n");
    668		return ret;
    669	}
    670
    671	ret = ziirave_wdt_revision(client, &w_priv->firmware_rev,
    672				   ZIIRAVE_WDT_FIRM_VER_MAJOR);
    673	if (ret) {
    674		dev_err(&client->dev, "Failed to read firmware version\n");
    675		return ret;
    676	}
    677
    678	dev_info(&client->dev,
    679		 "Firmware version: 02.%02u.%02u\n",
    680		 w_priv->firmware_rev.major, w_priv->firmware_rev.minor);
    681
    682	ret = ziirave_wdt_revision(client, &w_priv->bootloader_rev,
    683				   ZIIRAVE_WDT_BOOT_VER_MAJOR);
    684	if (ret) {
    685		dev_err(&client->dev, "Failed to read bootloader version\n");
    686		return ret;
    687	}
    688
    689	dev_info(&client->dev,
    690		 "Bootloader version: 01.%02u.%02u\n",
    691		 w_priv->bootloader_rev.major, w_priv->bootloader_rev.minor);
    692
    693	w_priv->reset_reason = i2c_smbus_read_byte_data(client,
    694						ZIIRAVE_WDT_RESET_REASON);
    695	if (w_priv->reset_reason < 0) {
    696		dev_err(&client->dev, "Failed to read reset reason\n");
    697		return w_priv->reset_reason;
    698	}
    699
    700	if (w_priv->reset_reason >= ARRAY_SIZE(ziirave_reasons) ||
    701	    !ziirave_reasons[w_priv->reset_reason]) {
    702		dev_err(&client->dev, "Invalid reset reason\n");
    703		return -ENODEV;
    704	}
    705
    706	ret = watchdog_register_device(&w_priv->wdd);
    707
    708	return ret;
    709}
    710
    711static int ziirave_wdt_remove(struct i2c_client *client)
    712{
    713	struct ziirave_wdt_data *w_priv = i2c_get_clientdata(client);
    714
    715	watchdog_unregister_device(&w_priv->wdd);
    716
    717	return 0;
    718}
    719
    720static const struct i2c_device_id ziirave_wdt_id[] = {
    721	{ "rave-wdt", 0 },
    722	{ }
    723};
    724MODULE_DEVICE_TABLE(i2c, ziirave_wdt_id);
    725
    726static const struct of_device_id zrv_wdt_of_match[] = {
    727	{ .compatible = "zii,rave-wdt", },
    728	{ },
    729};
    730MODULE_DEVICE_TABLE(of, zrv_wdt_of_match);
    731
    732static struct i2c_driver ziirave_wdt_driver = {
    733	.driver = {
    734		.name = "ziirave_wdt",
    735		.of_match_table = zrv_wdt_of_match,
    736	},
    737	.probe = ziirave_wdt_probe,
    738	.remove = ziirave_wdt_remove,
    739	.id_table = ziirave_wdt_id,
    740};
    741
    742module_i2c_driver(ziirave_wdt_driver);
    743
    744MODULE_AUTHOR("Martyn Welch <martyn.welch@collabora.co.uk");
    745MODULE_DESCRIPTION("Zodiac Aerospace RAVE Switch Watchdog Processor Driver");
    746MODULE_LICENSE("GPL");