/drivers/watchdog/sp805_wdt.c

  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 */
 67struct 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 */
 80static struct sp805_wdt *wdt;
 81static int nowayout = WATCHDOG_NOWAYOUT;
 82
 83/* This routine finds load value that will reset system in required timout */
 84static 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 occurred 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 */
109static 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 */
127static 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	/* Flush posted writes. */
138	readl(wdt->base + WDTLOCK);
139	spin_unlock(&wdt->lock);
140}
141
142/* disables watchdog timers reset */
143static void wdt_disable(void)
144{
145	spin_lock(&wdt->lock);
146
147	writel(UNLOCK, wdt->base + WDTLOCK);
148	writel(0, wdt->base + WDTCONTROL);
149	writel(LOCK, wdt->base + WDTLOCK);
150
151	/* Flush posted writes. */
152	readl(wdt->base + WDTLOCK);
153	spin_unlock(&wdt->lock);
154}
155
156static ssize_t sp805_wdt_write(struct file *file, const char *data,
157		size_t len, loff_t *ppos)
158{
159	if (len) {
160		if (!nowayout) {
161			size_t i;
162
163			clear_bit(WDT_CAN_BE_CLOSED, &wdt->status);
164
165			for (i = 0; i != len; i++) {
166				char c;
167
168				if (get_user(c, data + i))
169					return -EFAULT;
170				/* Check for Magic Close character */
171				if (c == 'V') {
172					set_bit(WDT_CAN_BE_CLOSED,
173							&wdt->status);
174					break;
175				}
176			}
177		}
178		wdt_enable();
179	}
180	return len;
181}
182
183static const struct watchdog_info ident = {
184	.options = WDIOF_MAGICCLOSE | WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING,
185	.identity = MODULE_NAME,
186};
187
188static long sp805_wdt_ioctl(struct file *file, unsigned int cmd,
189		unsigned long arg)
190{
191	int ret = -ENOTTY;
192	unsigned int timeout;
193
194	switch (cmd) {
195	case WDIOC_GETSUPPORT:
196		ret = copy_to_user((struct watchdog_info *)arg, &ident,
197				sizeof(ident)) ? -EFAULT : 0;
198		break;
199
200	case WDIOC_GETSTATUS:
201		ret = put_user(0, (int *)arg);
202		break;
203
204	case WDIOC_KEEPALIVE:
205		wdt_enable();
206		ret = 0;
207		break;
208
209	case WDIOC_SETTIMEOUT:
210		ret = get_user(timeout, (unsigned int *)arg);
211		if (ret)
212			break;
213
214		wdt_setload(timeout);
215
216		wdt_enable();
217		/* Fall through */
218
219	case WDIOC_GETTIMEOUT:
220		ret = put_user(wdt->timeout, (unsigned int *)arg);
221		break;
222	case WDIOC_GETTIMELEFT:
223		ret = put_user(wdt_timeleft(), (unsigned int *)arg);
224		break;
225	}
226	return ret;
227}
228
229static int sp805_wdt_open(struct inode *inode, struct file *file)
230{
231	int ret = 0;
232
233	if (test_and_set_bit(WDT_BUSY, &wdt->status))
234		return -EBUSY;
235
236	ret = clk_enable(wdt->clk);
237	if (ret) {
238		dev_err(&wdt->adev->dev, "clock enable fail");
239		goto err;
240	}
241
242	wdt_enable();
243
244	/* can not be closed, once enabled */
245	clear_bit(WDT_CAN_BE_CLOSED, &wdt->status);
246	return nonseekable_open(inode, file);
247
248err:
249	clear_bit(WDT_BUSY, &wdt->status);
250	return ret;
251}
252
253static int sp805_wdt_release(struct inode *inode, struct file *file)
254{
255	if (!test_bit(WDT_CAN_BE_CLOSED, &wdt->status)) {
256		clear_bit(WDT_BUSY, &wdt->status);
257		dev_warn(&wdt->adev->dev, "Device closed unexpectedly\n");
258		return 0;
259	}
260
261	wdt_disable();
262	clk_disable(wdt->clk);
263	clear_bit(WDT_BUSY, &wdt->status);
264
265	return 0;
266}
267
268static const struct file_operations sp805_wdt_fops = {
269	.owner = THIS_MODULE,
270	.llseek = no_llseek,
271	.write = sp805_wdt_write,
272	.unlocked_ioctl = sp805_wdt_ioctl,
273	.open = sp805_wdt_open,
274	.release = sp805_wdt_release,
275};
276
277static struct miscdevice sp805_wdt_miscdev = {
278	.minor = WATCHDOG_MINOR,
279	.name = "watchdog",
280	.fops = &sp805_wdt_fops,
281};
282
283static int __devinit
284sp805_wdt_probe(struct amba_device *adev, const struct amba_id *id)
285{
286	int ret = 0;
287
288	if (!request_mem_region(adev->res.start, resource_size(&adev->res),
289				"sp805_wdt")) {
290		dev_warn(&adev->dev, "Failed to get memory region resource\n");
291		ret = -ENOENT;
292		goto err;
293	}
294
295	wdt = kzalloc(sizeof(*wdt), GFP_KERNEL);
296	if (!wdt) {
297		dev_warn(&adev->dev, "Kzalloc failed\n");
298		ret = -ENOMEM;
299		goto err_kzalloc;
300	}
301
302	wdt->clk = clk_get(&adev->dev, NULL);
303	if (IS_ERR(wdt->clk)) {
304		dev_warn(&adev->dev, "Clock not found\n");
305		ret = PTR_ERR(wdt->clk);
306		goto err_clk_get;
307	}
308
309	wdt->base = ioremap(adev->res.start, resource_size(&adev->res));
310	if (!wdt->base) {
311		ret = -ENOMEM;
312		dev_warn(&adev->dev, "ioremap fail\n");
313		goto err_ioremap;
314	}
315
316	wdt->adev = adev;
317	spin_lock_init(&wdt->lock);
318	wdt_setload(DEFAULT_TIMEOUT);
319
320	ret = misc_register(&sp805_wdt_miscdev);
321	if (ret < 0) {
322		dev_warn(&adev->dev, "cannot register misc device\n");
323		goto err_misc_register;
324	}
325
326	dev_info(&adev->dev, "registration successful\n");
327	return 0;
328
329err_misc_register:
330	iounmap(wdt->base);
331err_ioremap:
332	clk_put(wdt->clk);
333err_clk_get:
334	kfree(wdt);
335	wdt = NULL;
336err_kzalloc:
337	release_mem_region(adev->res.start, resource_size(&adev->res));
338err:
339	dev_err(&adev->dev, "Probe Failed!!!\n");
340	return ret;
341}
342
343static int __devexit sp805_wdt_remove(struct amba_device *adev)
344{
345	misc_deregister(&sp805_wdt_miscdev);
346	iounmap(wdt->base);
347	clk_put(wdt->clk);
348	kfree(wdt);
349	release_mem_region(adev->res.start, resource_size(&adev->res));
350
351	return 0;
352}
353
354static struct amba_id sp805_wdt_ids[] __initdata = {
355	{
356		.id	= 0x00141805,
357		.mask	= 0x00ffffff,
358	},
359	{ 0, 0 },
360};
361
362static struct amba_driver sp805_wdt_driver = {
363	.drv = {
364		.name	= MODULE_NAME,
365	},
366	.id_table	= sp805_wdt_ids,
367	.probe		= sp805_wdt_probe,
368	.remove = __devexit_p(sp805_wdt_remove),
369};
370
371static int __init sp805_wdt_init(void)
372{
373	return amba_driver_register(&sp805_wdt_driver);
374}
375module_init(sp805_wdt_init);
376
377static void __exit sp805_wdt_exit(void)
378{
379	amba_driver_unregister(&sp805_wdt_driver);
380}
381module_exit(sp805_wdt_exit);
382
383module_param(nowayout, int, 0);
384MODULE_PARM_DESC(nowayout,
385		"Set to 1 to keep watchdog running after device release");
386
387MODULE_AUTHOR("Viresh Kumar <viresh.kumar@st.com>");
388MODULE_DESCRIPTION("ARM SP805 Watchdog Driver");
389MODULE_LICENSE("GPL");
390MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);