[deliverable/linux.git] / drivers / watchdog / sp805_wdt.c

/*
 * drivers/char/watchdog/sp805-wdt.c
 *
 * Watchdog driver for ARM SP805 watchdog module
 *
 * Copyright (C) 2010 ST Microelectronics
 * Viresh Kumar<viresh.kumar@st.com>
 *
 * This file is licensed under the terms of the GNU General Public
 * License version 2 or later. This program is licensed "as is" without any
 * warranty of any kind, whether express or implied.
 */

#include <linux/device.h>
#include <linux/resource.h>
#include <linux/amba/bus.h>
#include <linux/bitops.h>
#include <linux/clk.h>
#include <linux/fs.h>
#include <linux/init.h>
#include <linux/io.h>
#include <linux/ioport.h>
#include <linux/kernel.h>
#include <linux/math64.h>
#include <linux/miscdevice.h>
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/slab.h>
#include <linux/spinlock.h>
#include <linux/types.h>
#include <linux/uaccess.h>
#include <linux/watchdog.h>

/* default timeout in seconds */
#define DEFAULT_TIMEOUT		60

#define MODULE_NAME		"sp805-wdt"

/* watchdog register offsets and masks */
#define WDTLOAD			0x000
	#define LOAD_MIN	0x00000001
	#define LOAD_MAX	0xFFFFFFFF
#define WDTVALUE		0x004
#define WDTCONTROL		0x008
	/* control register masks */
	#define	INT_ENABLE	(1 << 0)
	#define	RESET_ENABLE	(1 << 1)
#define WDTINTCLR		0x00C
#define WDTRIS			0x010
#define WDTMIS			0x014
	#define INT_MASK	(1 << 0)
#define WDTLOCK			0xC00
	#define	UNLOCK		0x1ACCE551
	#define	LOCK		0x00000001

/**
 * struct sp805_wdt: sp805 wdt device structure
 *
 * lock: spin lock protecting dev structure and io access
 * base: base address of wdt
 * clk: clock structure of wdt
 * dev: amba device structure of wdt
 * status: current status of wdt
 * load_val: load value to be set for current timeout
 * timeout: current programmed timeout
 */
struct sp805_wdt {
	spinlock_t			lock;
	void __iomem			*base;
	struct clk			*clk;
	struct amba_device		*adev;
	unsigned long			status;
	#define WDT_BUSY		0
	#define WDT_CAN_BE_CLOSED	1
	unsigned int			load_val;
	unsigned int			timeout;
};

/* local variables */
static struct sp805_wdt *wdt;
static int nowayout = WATCHDOG_NOWAYOUT;

/* This routine finds load value that will reset system in required timout */
static void wdt_setload(unsigned int timeout)
{
	u64 load, rate;

	rate = clk_get_rate(wdt->clk);

	/*
	 * sp805 runs counter with given value twice, after the end of first
	 * counter it gives an interrupt and then starts counter again. If
	 * interrupt already occurred then it resets the system. This is why
	 * load is half of what should be required.
	 */
	load = div_u64(rate, 2) * timeout - 1;

	load = (load > LOAD_MAX) ? LOAD_MAX : load;
	load = (load < LOAD_MIN) ? LOAD_MIN : load;

	spin_lock(&wdt->lock);
	wdt->load_val = load;
	/* roundup timeout to closest positive integer value */
	wdt->timeout = div_u64((load + 1) * 2 + (rate / 2), rate);
	spin_unlock(&wdt->lock);
}

/* returns number of seconds left for reset to occur */
static u32 wdt_timeleft(void)
{
	u64 load, rate;

	rate = clk_get_rate(wdt->clk);

	spin_lock(&wdt->lock);
	load = readl(wdt->base + WDTVALUE);

	/*If the interrupt is inactive then time left is WDTValue + WDTLoad. */
	if (!(readl(wdt->base + WDTRIS) & INT_MASK))
		load += wdt->load_val + 1;
	spin_unlock(&wdt->lock);

	return div_u64(load, rate);
}

/* enables watchdog timers reset */
static void wdt_enable(void)
{
	spin_lock(&wdt->lock);

	writel(UNLOCK, wdt->base + WDTLOCK);
	writel(wdt->load_val, wdt->base + WDTLOAD);
	writel(INT_MASK, wdt->base + WDTINTCLR);
	writel(INT_ENABLE | RESET_ENABLE, wdt->base + WDTCONTROL);
	writel(LOCK, wdt->base + WDTLOCK);

	spin_unlock(&wdt->lock);
}

/* disables watchdog timers reset */
static void wdt_disable(void)
{
	spin_lock(&wdt->lock);

	writel(UNLOCK, wdt->base + WDTLOCK);
	writel(0, wdt->base + WDTCONTROL);
	writel(LOCK, wdt->base + WDTLOCK);

	spin_unlock(&wdt->lock);
}

static ssize_t sp805_wdt_write(struct file *file, const char *data,
		size_t len, loff_t *ppos)
{
	if (len) {
		if (!nowayout) {
			size_t i;

			clear_bit(WDT_CAN_BE_CLOSED, &wdt->status);

			for (i = 0; i != len; i++) {
				char c;

				if (get_user(c, data + i))
					return -EFAULT;
				/* Check for Magic Close character */
				if (c == 'V') {
					set_bit(WDT_CAN_BE_CLOSED,
							&wdt->status);
					break;
				}
			}
		}
		wdt_enable();
	}
	return len;
}

static const struct watchdog_info ident = {
	.options = WDIOF_MAGICCLOSE | WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING,
	.identity = MODULE_NAME,
};

static long sp805_wdt_ioctl(struct file *file, unsigned int cmd,
		unsigned long arg)
{
	int ret = -ENOTTY;
	unsigned int timeout;

	switch (cmd) {
	case WDIOC_GETSUPPORT:
		ret = copy_to_user((struct watchdog_info *)arg, &ident,
				sizeof(ident)) ? -EFAULT : 0;
		break;

	case WDIOC_GETSTATUS:
		ret = put_user(0, (int *)arg);
		break;

	case WDIOC_KEEPALIVE:
		wdt_enable();
		ret = 0;
		break;

	case WDIOC_SETTIMEOUT:
		ret = get_user(timeout, (unsigned int *)arg);
		if (ret)
			break;

		wdt_setload(timeout);

		wdt_enable();
		/* Fall through */

	case WDIOC_GETTIMEOUT:
		ret = put_user(wdt->timeout, (unsigned int *)arg);
		break;
	case WDIOC_GETTIMELEFT:
		ret = put_user(wdt_timeleft(), (unsigned int *)arg);
		break;
	}
	return ret;
}

static int sp805_wdt_open(struct inode *inode, struct file *file)
{
	int ret = 0;

	if (test_and_set_bit(WDT_BUSY, &wdt->status))
		return -EBUSY;

	ret = clk_enable(wdt->clk);
	if (ret) {
		dev_err(&wdt->adev->dev, "clock enable fail");
		goto err;
	}

	wdt_enable();

	/* can not be closed, once enabled */
	clear_bit(WDT_CAN_BE_CLOSED, &wdt->status);
	return nonseekable_open(inode, file);

err:
	clear_bit(WDT_BUSY, &wdt->status);
	return ret;
}

static int sp805_wdt_release(struct inode *inode, struct file *file)
{
	if (!test_bit(WDT_CAN_BE_CLOSED, &wdt->status)) {
		clear_bit(WDT_BUSY, &wdt->status);
		dev_warn(&wdt->adev->dev, "Device closed unexpectedly\n");
		return 0;
	}

	wdt_disable();
	clk_disable(wdt->clk);
	clear_bit(WDT_BUSY, &wdt->status);

	return 0;
}

static const struct file_operations sp805_wdt_fops = {
	.owner = THIS_MODULE,
	.llseek = no_llseek,
	.write = sp805_wdt_write,
	.unlocked_ioctl = sp805_wdt_ioctl,
	.open = sp805_wdt_open,
	.release = sp805_wdt_release,
};

static struct miscdevice sp805_wdt_miscdev = {
	.minor = WATCHDOG_MINOR,
	.name = "watchdog",
	.fops = &sp805_wdt_fops,
};

static int __devinit
sp805_wdt_probe(struct amba_device *adev, const struct amba_id *id)
{
	int ret = 0;

	if (!request_mem_region(adev->res.start, resource_size(&adev->res),
				"sp805_wdt")) {
		dev_warn(&adev->dev, "Failed to get memory region resource\n");
		ret = -ENOENT;
		goto err;
	}

	wdt = kzalloc(sizeof(*wdt), GFP_KERNEL);
	if (!wdt) {
		dev_warn(&adev->dev, "Kzalloc failed\n");
		ret = -ENOMEM;
		goto err_kzalloc;
	}

	wdt->clk = clk_get(&adev->dev, NULL);
	if (IS_ERR(wdt->clk)) {
		dev_warn(&adev->dev, "Clock not found\n");
		ret = PTR_ERR(wdt->clk);
		goto err_clk_get;
	}

	wdt->base = ioremap(adev->res.start, resource_size(&adev->res));
	if (!wdt->base) {
		ret = -ENOMEM;
		dev_warn(&adev->dev, "ioremap fail\n");
		goto err_ioremap;
	}

	wdt->adev = adev;
	spin_lock_init(&wdt->lock);
	wdt_setload(DEFAULT_TIMEOUT);

	ret = misc_register(&sp805_wdt_miscdev);
	if (ret < 0) {
		dev_warn(&adev->dev, "cannot register misc device\n");
		goto err_misc_register;
	}

	dev_info(&adev->dev, "registration successful\n");
	return 0;

err_misc_register:
	iounmap(wdt->base);
err_ioremap:
	clk_put(wdt->clk);
err_clk_get:
	kfree(wdt);
	wdt = NULL;
err_kzalloc:
	release_mem_region(adev->res.start, resource_size(&adev->res));
err:
	dev_err(&adev->dev, "Probe Failed!!!\n");
	return ret;
}

static int __devexit sp805_wdt_remove(struct amba_device *adev)
{
	misc_deregister(&sp805_wdt_miscdev);
	iounmap(wdt->base);
	clk_put(wdt->clk);
	kfree(wdt);
	release_mem_region(adev->res.start, resource_size(&adev->res));

	return 0;
}

static struct amba_id sp805_wdt_ids[] __initdata = {
	{
		.id	= 0x00141805,
		.mask	= 0x00ffffff,
	},
	{ 0, 0 },
};

static struct amba_driver sp805_wdt_driver = {
	.drv = {
		.name	= MODULE_NAME,
	},
	.id_table	= sp805_wdt_ids,
	.probe		= sp805_wdt_probe,
	.remove = __devexit_p(sp805_wdt_remove),
};

static int __init sp805_wdt_init(void)
{
	return amba_driver_register(&sp805_wdt_driver);
}
module_init(sp805_wdt_init);

static void __exit sp805_wdt_exit(void)
{
	amba_driver_unregister(&sp805_wdt_driver);
}
module_exit(sp805_wdt_exit);

module_param(nowayout, int, 0);
MODULE_PARM_DESC(nowayout,
		"Set to 1 to keep watchdog running after device release");

MODULE_AUTHOR("Viresh Kumar <viresh.kumar@st.com>");
MODULE_DESCRIPTION("ARM SP805 Watchdog Driver");
MODULE_LICENSE("GPL");
MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
Commit	Line	Data
4a370278 VK	1	/*
	2	* drivers/char/watchdog/sp805-wdt.c
	3	*
	4	* Watchdog driver for ARM SP805 watchdog module
	5	*
	6	* Copyright (C) 2010 ST Microelectronics
	7	* Viresh Kumar<viresh.kumar@st.com>
	8	*
	9	* This file is licensed under the terms of the GNU General Public
	10	* License version 2 or later. This program is licensed "as is" without any
	11	* warranty of any kind, whether express or implied.
	12	*/
	13
	14	#include <linux/device.h>
	15	#include <linux/resource.h>
	16	#include <linux/amba/bus.h>
	17	#include <linux/bitops.h>
	18	#include <linux/clk.h>
	19	#include <linux/fs.h>
	20	#include <linux/init.h>
	21	#include <linux/io.h>
	22	#include <linux/ioport.h>
	23	#include <linux/kernel.h>
	24	#include <linux/math64.h>
	25	#include <linux/miscdevice.h>
	26	#include <linux/module.h>
	27	#include <linux/moduleparam.h>
	28	#include <linux/slab.h>
	29	#include <linux/spinlock.h>
	30	#include <linux/types.h>
	31	#include <linux/uaccess.h>
	32	#include <linux/watchdog.h>
	33
	34	/* default timeout in seconds */
	35	#define DEFAULT_TIMEOUT 60
	36
	37	#define MODULE_NAME "sp805-wdt"
	38
	39	/* watchdog register offsets and masks */
	40	#define WDTLOAD 0x000
	41	#define LOAD_MIN 0x00000001
	42	#define LOAD_MAX 0xFFFFFFFF
	43	#define WDTVALUE 0x004
	44	#define WDTCONTROL 0x008
	45	/* control register masks */
	46	#define INT_ENABLE (1 << 0)
	47	#define RESET_ENABLE (1 << 1)
	48	#define WDTINTCLR 0x00C
	49	#define WDTRIS 0x010
	50	#define WDTMIS 0x014
	51	#define INT_MASK (1 << 0)
	52	#define WDTLOCK 0xC00
	53	#define UNLOCK 0x1ACCE551
	54	#define LOCK 0x00000001
	55
	56	/**
	57	* struct sp805_wdt: sp805 wdt device structure
	58	*
	59	* lock: spin lock protecting dev structure and io access
	60	* base: base address of wdt
	61	* clk: clock structure of wdt
	62	* dev: amba device structure of wdt
	63	* status: current status of wdt
	64	* load_val: load value to be set for current timeout
65	* timeout: current programmed timeout
66	*/
67	struct sp805_wdt {
68	spinlock_t lock;
69	void __iomem *base;
70	struct clk *clk;
71	struct amba_device *adev;
72	unsigned long status;
73	#define WDT_BUSY 0
74	#define WDT_CAN_BE_CLOSED 1
75	unsigned int load_val;
76	unsigned int timeout;
77	};
78
79	/* local variables */
80	static struct sp805_wdt *wdt;
81	static int nowayout = WATCHDOG_NOWAYOUT;
82
83	/* This routine finds load value that will reset system in required timout */
84	static void wdt_setload(unsigned int timeout)
85	{
86	u64 load, rate;
87
88	rate = clk_get_rate(wdt->clk);
89
90	/*
91	* sp805 runs counter with given value twice, after the end of first
92	* counter it gives an interrupt and then starts counter again. If
25985edc	93	* interrupt already occurred then it resets the system. This is why
4a370278 VK	94	* load is half of what should be required.
	95	*/
	96	load = div_u64(rate, 2) * timeout - 1;
	97
	98	load = (load > LOAD_MAX) ? LOAD_MAX : load;
	99	load = (load < LOAD_MIN) ? LOAD_MIN : load;
	100
	101	spin_lock(&wdt->lock);
	102	wdt->load_val = load;
	103	/* roundup timeout to closest positive integer value */
	104	wdt->timeout = div_u64((load + 1) * 2 + (rate / 2), rate);
	105	spin_unlock(&wdt->lock);
	106	}
	107
	108	/* returns number of seconds left for reset to occur */
	109	static u32 wdt_timeleft(void)
	110	{
	111	u64 load, rate;
	112
	113	rate = clk_get_rate(wdt->clk);
	114
	115	spin_lock(&wdt->lock);
	116	load = readl(wdt->base + WDTVALUE);
	117
	118	/If the interrupt is inactive then time left is WDTValue + WDTLoad. /
	119	if (!(readl(wdt->base + WDTRIS) & INT_MASK))
	120	load += wdt->load_val + 1;
	121	spin_unlock(&wdt->lock);
	122
	123	return div_u64(load, rate);
	124	}
	125
	126	/* enables watchdog timers reset */
	127	static void wdt_enable(void)
	128	{
	129	spin_lock(&wdt->lock);
	130
	131	writel(UNLOCK, wdt->base + WDTLOCK);
	132	writel(wdt->load_val, wdt->base + WDTLOAD);
	133	writel(INT_MASK, wdt->base + WDTINTCLR);
	134	writel(INT_ENABLE \| RESET_ENABLE, wdt->base + WDTCONTROL);
	135	writel(LOCK, wdt->base + WDTLOCK);
	136
	137	spin_unlock(&wdt->lock);
	138	}
	139
	140	/* disables watchdog timers reset */
	141	static void wdt_disable(void)
	142	{
	143	spin_lock(&wdt->lock);
	144
	145	writel(UNLOCK, wdt->base + WDTLOCK);
	146	writel(0, wdt->base + WDTCONTROL);
4a370278 VK	147	writel(LOCK, wdt->base + WDTLOCK);
	148
	149	spin_unlock(&wdt->lock);
	150	}
	151
	152	static ssize_t sp805_wdt_write(struct file file, const char data,
	153	size_t len, loff_t *ppos)
	154	{
	155	if (len) {
	156	if (!nowayout) {
	157	size_t i;
	158
	159	clear_bit(WDT_CAN_BE_CLOSED, &wdt->status);
	160
	161	for (i = 0; i != len; i++) {
	162	char c;
	163
	164	if (get_user(c, data + i))
	165	return -EFAULT;
	166	/* Check for Magic Close character */
	167	if (c == 'V') {
	168	set_bit(WDT_CAN_BE_CLOSED,
	169	&wdt->status);
	170	break;
	171	}
	172	}
	173	}
	174	wdt_enable();
	175	}
	176	return len;
	177	}
	178
	179	static const struct watchdog_info ident = {
	180	.options = WDIOF_MAGICCLOSE \| WDIOF_SETTIMEOUT \| WDIOF_KEEPALIVEPING,
	181	.identity = MODULE_NAME,
	182	};
	183
	184	static long sp805_wdt_ioctl(struct file *file, unsigned int cmd,
	185	unsigned long arg)
	186	{
	187	int ret = -ENOTTY;
	188	unsigned int timeout;
	189
	190	switch (cmd) {
	191	case WDIOC_GETSUPPORT:
	192	ret = copy_to_user((struct watchdog_info *)arg, &ident,
	193	sizeof(ident)) ? -EFAULT : 0;
	194	break;
	195
	196	case WDIOC_GETSTATUS:
	197	ret = put_user(0, (int *)arg);
	198	break;
	199
	200	case WDIOC_KEEPALIVE:
	201	wdt_enable();
	202	ret = 0;
	203	break;
	204
	205	case WDIOC_SETTIMEOUT:
	206	ret = get_user(timeout, (unsigned int *)arg);
	207	if (ret)
	208	break;
	209
	210	wdt_setload(timeout);
211
212	wdt_enable();
213	/* Fall through */
214
215	case WDIOC_GETTIMEOUT:
216	ret = put_user(wdt->timeout, (unsigned int *)arg);
217	break;
218	case WDIOC_GETTIMELEFT:
219	ret = put_user(wdt_timeleft(), (unsigned int *)arg);
220	break;
221	}
222	return ret;
223	}
224
225	static int sp805_wdt_open(struct inode inode, struct file file)
226	{
227	int ret = 0;
228
229	if (test_and_set_bit(WDT_BUSY, &wdt->status))
230	return -EBUSY;
231
232	ret = clk_enable(wdt->clk);
233	if (ret) {
234	dev_err(&wdt->adev->dev, "clock enable fail");
235	goto err;
236	}
237
238	wdt_enable();
239
240	/* can not be closed, once enabled */
241	clear_bit(WDT_CAN_BE_CLOSED, &wdt->status);
242	return nonseekable_open(inode, file);
243
244	err:
245	clear_bit(WDT_BUSY, &wdt->status);
246	return ret;
247	}
248
249	static int sp805_wdt_release(struct inode inode, struct file file)
250	{
251	if (!test_bit(WDT_CAN_BE_CLOSED, &wdt->status)) {
252	clear_bit(WDT_BUSY, &wdt->status);
253	dev_warn(&wdt->adev->dev, "Device closed unexpectedly\n");
254	return 0;
255	}
256
257	wdt_disable();
258	clk_disable(wdt->clk);
259	clear_bit(WDT_BUSY, &wdt->status);
260
261	return 0;
262	}
263
264	static const struct file_operations sp805_wdt_fops = {
265	.owner = THIS_MODULE,
266	.llseek = no_llseek,
267	.write = sp805_wdt_write,
268	.unlocked_ioctl = sp805_wdt_ioctl,
269	.open = sp805_wdt_open,
270	.release = sp805_wdt_release,
271	};
272
273	static struct miscdevice sp805_wdt_miscdev = {
274	.minor = WATCHDOG_MINOR,
275	.name = "watchdog",
276	.fops = &sp805_wdt_fops,
277	};
278
279	static int __devinit
aa25afad	280	sp805_wdt_probe(struct amba_device adev, const struct amba_id id)
4a370278 VK	281	{
	282	int ret = 0;
	283
	284	if (!request_mem_region(adev->res.start, resource_size(&adev->res),
	285	"sp805_wdt")) {
	286	dev_warn(&adev->dev, "Failed to get memory region resource\n");
	287	ret = -ENOENT;
	288	goto err;
	289	}
	290
	291	wdt = kzalloc(sizeof(*wdt), GFP_KERNEL);
	292	if (!wdt) {
	293	dev_warn(&adev->dev, "Kzalloc failed\n");
	294	ret = -ENOMEM;
	295	goto err_kzalloc;
	296	}
	297
	298	wdt->clk = clk_get(&adev->dev, NULL);
	299	if (IS_ERR(wdt->clk)) {
	300	dev_warn(&adev->dev, "Clock not found\n");
	301	ret = PTR_ERR(wdt->clk);
	302	goto err_clk_get;
	303	}
	304
	305	wdt->base = ioremap(adev->res.start, resource_size(&adev->res));
	306	if (!wdt->base) {
	307	ret = -ENOMEM;
	308	dev_warn(&adev->dev, "ioremap fail\n");
	309	goto err_ioremap;
	310	}
	311
	312	wdt->adev = adev;
	313	spin_lock_init(&wdt->lock);
	314	wdt_setload(DEFAULT_TIMEOUT);
	315
	316	ret = misc_register(&sp805_wdt_miscdev);
	317	if (ret < 0) {
	318	dev_warn(&adev->dev, "cannot register misc device\n");
	319	goto err_misc_register;
	320	}
	321
	322	dev_info(&adev->dev, "registration successful\n");
	323	return 0;
	324
	325	err_misc_register:
	326	iounmap(wdt->base);
	327	err_ioremap:
	328	clk_put(wdt->clk);
	329	err_clk_get:
	330	kfree(wdt);
	331	wdt = NULL;
	332	err_kzalloc:
	333	release_mem_region(adev->res.start, resource_size(&adev->res));
	334	err:
	335	dev_err(&adev->dev, "Probe Failed!!!\n");
	336	return ret;
	337	}
	338
	339	static int __devexit sp805_wdt_remove(struct amba_device *adev)
	340	{
	341	misc_deregister(&sp805_wdt_miscdev);
	342	iounmap(wdt->base);
	343	clk_put(wdt->clk);
	344	kfree(wdt);
345	release_mem_region(adev->res.start, resource_size(&adev->res));
346
347	return 0;
348	}
349
350	static struct amba_id sp805_wdt_ids[] __initdata = {
351	{
352	.id = 0x00141805,
353	.mask = 0x00ffffff,
354	},
355	{ 0, 0 },
356	};
357
358	static struct amba_driver sp805_wdt_driver = {
359	.drv = {
360	.name = MODULE_NAME,
361	},
362	.id_table = sp805_wdt_ids,
363	.probe = sp805_wdt_probe,
364	.remove = __devexit_p(sp805_wdt_remove),
365	};
366
367	static int __init sp805_wdt_init(void)
368	{
369	return amba_driver_register(&sp805_wdt_driver);
370	}
371	module_init(sp805_wdt_init);
372
373	static void __exit sp805_wdt_exit(void)
374	{
375	amba_driver_unregister(&sp805_wdt_driver);
376	}
377	module_exit(sp805_wdt_exit);
378
379	module_param(nowayout, int, 0);
380	MODULE_PARM_DESC(nowayout,
381	"Set to 1 to keep watchdog running after device release");
382
383	MODULE_AUTHOR("Viresh Kumar <viresh.kumar@st.com>");
384	MODULE_DESCRIPTION("ARM SP805 Watchdog Driver");
385	MODULE_LICENSE("GPL");
386	MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);