[net-next-2.6.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 occured 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(0, wdt->base + WDTLOAD);
	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, 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
93	* interrupt already occured then it resets the system. This is why
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);
147	writel(0, wdt->base + WDTLOAD);
148	writel(LOCK, wdt->base + WDTLOCK);
149
150	spin_unlock(&wdt->lock);
151	}
152
153	static ssize_t sp805_wdt_write(struct file file, const char data,
154	size_t len, loff_t *ppos)
155	{
156	if (len) {
157	if (!nowayout) {
158	size_t i;
159
160	clear_bit(WDT_CAN_BE_CLOSED, &wdt->status);
161
162	for (i = 0; i != len; i++) {
163	char c;
164
165	if (get_user(c, data + i))
166	return -EFAULT;
167	/* Check for Magic Close character */
168	if (c == 'V') {
169	set_bit(WDT_CAN_BE_CLOSED,
170	&wdt->status);
171	break;
172	}
173	}
174	}
175	wdt_enable();
176	}
177	return len;
178	}
179
180	static const struct watchdog_info ident = {
181	.options = WDIOF_MAGICCLOSE \| WDIOF_SETTIMEOUT \| WDIOF_KEEPALIVEPING,
182	.identity = MODULE_NAME,
183	};
184
185	static long sp805_wdt_ioctl(struct file *file, unsigned int cmd,
186	unsigned long arg)
187	{
188	int ret = -ENOTTY;
189	unsigned int timeout;
190
191	switch (cmd) {
192	case WDIOC_GETSUPPORT:
193	ret = copy_to_user((struct watchdog_info *)arg, &ident,
194	sizeof(ident)) ? -EFAULT : 0;
195	break;
196
197	case WDIOC_GETSTATUS:
198	ret = put_user(0, (int *)arg);
199	break;
200
201	case WDIOC_KEEPALIVE:
202	wdt_enable();
203	ret = 0;
204	break;
205
206	case WDIOC_SETTIMEOUT:
207	ret = get_user(timeout, (unsigned int *)arg);
208	if (ret)
209	break;
210
211	wdt_setload(timeout);
212
213	wdt_enable();
214	/* Fall through */
215
216	case WDIOC_GETTIMEOUT:
217	ret = put_user(wdt->timeout, (unsigned int *)arg);
218	break;
219	case WDIOC_GETTIMELEFT:
220	ret = put_user(wdt_timeleft(), (unsigned int *)arg);
221	break;
222	}
223	return ret;
224	}
225
226	static int sp805_wdt_open(struct inode inode, struct file file)
227	{
228	int ret = 0;
229
230	if (test_and_set_bit(WDT_BUSY, &wdt->status))
231	return -EBUSY;
232
233	ret = clk_enable(wdt->clk);
234	if (ret) {
235	dev_err(&wdt->adev->dev, "clock enable fail");
236	goto err;
237	}
238
239	wdt_enable();
240
241	/* can not be closed, once enabled */
242	clear_bit(WDT_CAN_BE_CLOSED, &wdt->status);
243	return nonseekable_open(inode, file);
244
245	err:
246	clear_bit(WDT_BUSY, &wdt->status);
247	return ret;
248	}
249
250	static int sp805_wdt_release(struct inode inode, struct file file)
251	{
252	if (!test_bit(WDT_CAN_BE_CLOSED, &wdt->status)) {
253	clear_bit(WDT_BUSY, &wdt->status);
254	dev_warn(&wdt->adev->dev, "Device closed unexpectedly\n");
255	return 0;
256	}
257
258	wdt_disable();
259	clk_disable(wdt->clk);
260	clear_bit(WDT_BUSY, &wdt->status);
261
262	return 0;
263	}
264
265	static const struct file_operations sp805_wdt_fops = {
266	.owner = THIS_MODULE,
267	.llseek = no_llseek,
268	.write = sp805_wdt_write,
269	.unlocked_ioctl = sp805_wdt_ioctl,
270	.open = sp805_wdt_open,
271	.release = sp805_wdt_release,
272	};
273
274	static struct miscdevice sp805_wdt_miscdev = {
275	.minor = WATCHDOG_MINOR,
276	.name = "watchdog",
277	.fops = &sp805_wdt_fops,
278	};
279
280	static int __devinit
281	sp805_wdt_probe(struct amba_device adev, struct amba_id id)
282	{
283	int ret = 0;
284
285	if (!request_mem_region(adev->res.start, resource_size(&adev->res),
286	"sp805_wdt")) {
287	dev_warn(&adev->dev, "Failed to get memory region resource\n");
288	ret = -ENOENT;
289	goto err;
290	}
291
292	wdt = kzalloc(sizeof(*wdt), GFP_KERNEL);
293	if (!wdt) {
294	dev_warn(&adev->dev, "Kzalloc failed\n");
295	ret = -ENOMEM;
296	goto err_kzalloc;
297	}
298
299	wdt->clk = clk_get(&adev->dev, NULL);
300	if (IS_ERR(wdt->clk)) {
301	dev_warn(&adev->dev, "Clock not found\n");
302	ret = PTR_ERR(wdt->clk);
303	goto err_clk_get;
304	}
305
306	wdt->base = ioremap(adev->res.start, resource_size(&adev->res));
307	if (!wdt->base) {
308	ret = -ENOMEM;
309	dev_warn(&adev->dev, "ioremap fail\n");
310	goto err_ioremap;
311	}
312
313	wdt->adev = adev;
314	spin_lock_init(&wdt->lock);
315	wdt_setload(DEFAULT_TIMEOUT);
316
317	ret = misc_register(&sp805_wdt_miscdev);
318	if (ret < 0) {
319	dev_warn(&adev->dev, "cannot register misc device\n");
320	goto err_misc_register;
321	}
322
323	dev_info(&adev->dev, "registration successful\n");
324	return 0;
325
326	err_misc_register:
327	iounmap(wdt->base);
328	err_ioremap:
329	clk_put(wdt->clk);
330	err_clk_get:
331	kfree(wdt);
332	wdt = NULL;
333	err_kzalloc:
334	release_mem_region(adev->res.start, resource_size(&adev->res));
335	err:
336	dev_err(&adev->dev, "Probe Failed!!!\n");
337	return ret;
338	}
339
340	static int __devexit sp805_wdt_remove(struct amba_device *adev)
341	{
342	misc_deregister(&sp805_wdt_miscdev);
343	iounmap(wdt->base);
344	clk_put(wdt->clk);
345	kfree(wdt);
346	release_mem_region(adev->res.start, resource_size(&adev->res));
347
348	return 0;
349	}
350
351	static struct amba_id sp805_wdt_ids[] __initdata = {
352	{
353	.id = 0x00141805,
354	.mask = 0x00ffffff,
355	},
356	{ 0, 0 },
357	};
358
359	static struct amba_driver sp805_wdt_driver = {
360	.drv = {
361	.name = MODULE_NAME,
362	},
363	.id_table = sp805_wdt_ids,
364	.probe = sp805_wdt_probe,
365	.remove = __devexit_p(sp805_wdt_remove),
366	};
367
368	static int __init sp805_wdt_init(void)
369	{
370	return amba_driver_register(&sp805_wdt_driver);
371	}
372	module_init(sp805_wdt_init);
373
374	static void __exit sp805_wdt_exit(void)
375	{
376	amba_driver_unregister(&sp805_wdt_driver);
377	}
378	module_exit(sp805_wdt_exit);
379
380	module_param(nowayout, int, 0);
381	MODULE_PARM_DESC(nowayout,
382	"Set to 1 to keep watchdog running after device release");
383
384	MODULE_AUTHOR("Viresh Kumar <viresh.kumar@st.com>");
385	MODULE_DESCRIPTION("ARM SP805 Watchdog Driver");
386	MODULE_LICENSE("GPL");
387	MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);