Merge branch 'for-next' of git://git.kernel.org/pub/scm/linux/kernel/git/nab/target...
[linux-btrfs-devel.git] / drivers / watchdog / dw_wdt.c
blobf10f8c0abba45b0819c9be82805058f7d2d4b38d
1 /*
2 * Copyright 2010-2011 Picochip Ltd., Jamie Iles
3 * http://www.picochip.com
5 * This program is free software; you can redistribute it and/or
6 * modify it under the terms of the GNU General Public License
7 * as published by the Free Software Foundation; either version
8 * 2 of the License, or (at your option) any later version.
10 * This file implements a driver for the Synopsys DesignWare watchdog device
11 * in the many ARM subsystems. The watchdog has 16 different timeout periods
12 * and these are a function of the input clock frequency.
14 * The DesignWare watchdog cannot be stopped once it has been started so we
15 * use a software timer to implement a ping that will keep the watchdog alive.
16 * If we receive an expected close for the watchdog then we keep the timer
17 * running, otherwise the timer is stopped and the watchdog will expire.
19 #define pr_fmt(fmt) "dw_wdt: " fmt
21 #include <linux/bitops.h>
22 #include <linux/clk.h>
23 #include <linux/device.h>
24 #include <linux/err.h>
25 #include <linux/fs.h>
26 #include <linux/io.h>
27 #include <linux/kernel.h>
28 #include <linux/miscdevice.h>
29 #include <linux/module.h>
30 #include <linux/moduleparam.h>
31 #include <linux/pm.h>
32 #include <linux/platform_device.h>
33 #include <linux/spinlock.h>
34 #include <linux/timer.h>
35 #include <linux/uaccess.h>
36 #include <linux/watchdog.h>
38 #define WDOG_CONTROL_REG_OFFSET 0x00
39 #define WDOG_CONTROL_REG_WDT_EN_MASK 0x01
40 #define WDOG_TIMEOUT_RANGE_REG_OFFSET 0x04
41 #define WDOG_CURRENT_COUNT_REG_OFFSET 0x08
42 #define WDOG_COUNTER_RESTART_REG_OFFSET 0x0c
43 #define WDOG_COUNTER_RESTART_KICK_VALUE 0x76
45 /* The maximum TOP (timeout period) value that can be set in the watchdog. */
46 #define DW_WDT_MAX_TOP 15
48 static int nowayout = WATCHDOG_NOWAYOUT;
49 module_param(nowayout, int, 0);
50 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started "
51 "(default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
53 #define WDT_TIMEOUT (HZ / 2)
55 static struct {
56 spinlock_t lock;
57 void __iomem *regs;
58 struct clk *clk;
59 unsigned long in_use;
60 unsigned long next_heartbeat;
61 struct timer_list timer;
62 int expect_close;
63 } dw_wdt;
65 static inline int dw_wdt_is_enabled(void)
67 return readl(dw_wdt.regs + WDOG_CONTROL_REG_OFFSET) &
68 WDOG_CONTROL_REG_WDT_EN_MASK;
71 static inline int dw_wdt_top_in_seconds(unsigned top)
74 * There are 16 possible timeout values in 0..15 where the number of
75 * cycles is 2 ^ (16 + i) and the watchdog counts down.
77 return (1 << (16 + top)) / clk_get_rate(dw_wdt.clk);
80 static int dw_wdt_get_top(void)
82 int top = readl(dw_wdt.regs + WDOG_TIMEOUT_RANGE_REG_OFFSET) & 0xF;
84 return dw_wdt_top_in_seconds(top);
87 static inline void dw_wdt_set_next_heartbeat(void)
89 dw_wdt.next_heartbeat = jiffies + dw_wdt_get_top() * HZ;
92 static int dw_wdt_set_top(unsigned top_s)
94 int i, top_val = DW_WDT_MAX_TOP;
97 * Iterate over the timeout values until we find the closest match. We
98 * always look for >=.
100 for (i = 0; i <= DW_WDT_MAX_TOP; ++i)
101 if (dw_wdt_top_in_seconds(i) >= top_s) {
102 top_val = i;
103 break;
106 /* Set the new value in the watchdog. */
107 writel(top_val, dw_wdt.regs + WDOG_TIMEOUT_RANGE_REG_OFFSET);
109 dw_wdt_set_next_heartbeat();
111 return dw_wdt_top_in_seconds(top_val);
114 static void dw_wdt_keepalive(void)
116 writel(WDOG_COUNTER_RESTART_KICK_VALUE, dw_wdt.regs +
117 WDOG_COUNTER_RESTART_REG_OFFSET);
120 static void dw_wdt_ping(unsigned long data)
122 if (time_before(jiffies, dw_wdt.next_heartbeat) ||
123 (!nowayout && !dw_wdt.in_use)) {
124 dw_wdt_keepalive();
125 mod_timer(&dw_wdt.timer, jiffies + WDT_TIMEOUT);
126 } else
127 pr_crit("keepalive missed, machine will reset\n");
130 static int dw_wdt_open(struct inode *inode, struct file *filp)
132 if (test_and_set_bit(0, &dw_wdt.in_use))
133 return -EBUSY;
135 /* Make sure we don't get unloaded. */
136 __module_get(THIS_MODULE);
138 spin_lock(&dw_wdt.lock);
139 if (!dw_wdt_is_enabled()) {
141 * The watchdog is not currently enabled. Set the timeout to
142 * the maximum and then start it.
144 dw_wdt_set_top(DW_WDT_MAX_TOP);
145 writel(WDOG_CONTROL_REG_WDT_EN_MASK,
146 dw_wdt.regs + WDOG_CONTROL_REG_OFFSET);
149 dw_wdt_set_next_heartbeat();
151 spin_unlock(&dw_wdt.lock);
153 return nonseekable_open(inode, filp);
156 ssize_t dw_wdt_write(struct file *filp, const char __user *buf, size_t len,
157 loff_t *offset)
159 if (!len)
160 return 0;
162 if (!nowayout) {
163 size_t i;
165 dw_wdt.expect_close = 0;
167 for (i = 0; i < len; ++i) {
168 char c;
170 if (get_user(c, buf + i))
171 return -EFAULT;
173 if (c == 'V') {
174 dw_wdt.expect_close = 1;
175 break;
180 dw_wdt_set_next_heartbeat();
181 mod_timer(&dw_wdt.timer, jiffies + WDT_TIMEOUT);
183 return len;
186 static u32 dw_wdt_time_left(void)
188 return readl(dw_wdt.regs + WDOG_CURRENT_COUNT_REG_OFFSET) /
189 clk_get_rate(dw_wdt.clk);
192 static const struct watchdog_info dw_wdt_ident = {
193 .options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT |
194 WDIOF_MAGICCLOSE,
195 .identity = "Synopsys DesignWare Watchdog",
198 static long dw_wdt_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
200 unsigned long val;
201 int timeout;
203 switch (cmd) {
204 case WDIOC_GETSUPPORT:
205 return copy_to_user((struct watchdog_info *)arg, &dw_wdt_ident,
206 sizeof(dw_wdt_ident)) ? -EFAULT : 0;
208 case WDIOC_GETSTATUS:
209 case WDIOC_GETBOOTSTATUS:
210 return put_user(0, (int *)arg);
212 case WDIOC_KEEPALIVE:
213 dw_wdt_set_next_heartbeat();
214 return 0;
216 case WDIOC_SETTIMEOUT:
217 if (get_user(val, (int __user *)arg))
218 return -EFAULT;
219 timeout = dw_wdt_set_top(val);
220 return put_user(timeout , (int __user *)arg);
222 case WDIOC_GETTIMEOUT:
223 return put_user(dw_wdt_get_top(), (int __user *)arg);
225 case WDIOC_GETTIMELEFT:
226 /* Get the time left until expiry. */
227 if (get_user(val, (int __user *)arg))
228 return -EFAULT;
229 return put_user(dw_wdt_time_left(), (int __user *)arg);
231 default:
232 return -ENOTTY;
236 static int dw_wdt_release(struct inode *inode, struct file *filp)
238 clear_bit(0, &dw_wdt.in_use);
240 if (!dw_wdt.expect_close) {
241 del_timer(&dw_wdt.timer);
243 if (!nowayout)
244 pr_crit("unexpected close, system will reboot soon\n");
245 else
246 pr_crit("watchdog cannot be disabled, system will reboot soon\n");
249 dw_wdt.expect_close = 0;
251 return 0;
254 #ifdef CONFIG_PM
255 static int dw_wdt_suspend(struct device *dev)
257 clk_disable(dw_wdt.clk);
259 return 0;
262 static int dw_wdt_resume(struct device *dev)
264 int err = clk_enable(dw_wdt.clk);
266 if (err)
267 return err;
269 dw_wdt_keepalive();
271 return 0;
274 static const struct dev_pm_ops dw_wdt_pm_ops = {
275 .suspend = dw_wdt_suspend,
276 .resume = dw_wdt_resume,
278 #endif /* CONFIG_PM */
280 static const struct file_operations wdt_fops = {
281 .owner = THIS_MODULE,
282 .llseek = no_llseek,
283 .open = dw_wdt_open,
284 .write = dw_wdt_write,
285 .unlocked_ioctl = dw_wdt_ioctl,
286 .release = dw_wdt_release
289 static struct miscdevice dw_wdt_miscdev = {
290 .fops = &wdt_fops,
291 .name = "watchdog",
292 .minor = WATCHDOG_MINOR,
295 static int __devinit dw_wdt_drv_probe(struct platform_device *pdev)
297 int ret;
298 struct resource *mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
300 if (!mem)
301 return -EINVAL;
303 if (!devm_request_mem_region(&pdev->dev, mem->start, resource_size(mem),
304 "dw_wdt"))
305 return -ENOMEM;
307 dw_wdt.regs = devm_ioremap(&pdev->dev, mem->start, resource_size(mem));
308 if (!dw_wdt.regs)
309 return -ENOMEM;
311 dw_wdt.clk = clk_get(&pdev->dev, NULL);
312 if (IS_ERR(dw_wdt.clk))
313 return PTR_ERR(dw_wdt.clk);
315 ret = clk_enable(dw_wdt.clk);
316 if (ret)
317 goto out_put_clk;
319 spin_lock_init(&dw_wdt.lock);
321 ret = misc_register(&dw_wdt_miscdev);
322 if (ret)
323 goto out_disable_clk;
325 dw_wdt_set_next_heartbeat();
326 setup_timer(&dw_wdt.timer, dw_wdt_ping, 0);
327 mod_timer(&dw_wdt.timer, jiffies + WDT_TIMEOUT);
329 return 0;
331 out_disable_clk:
332 clk_disable(dw_wdt.clk);
333 out_put_clk:
334 clk_put(dw_wdt.clk);
336 return ret;
339 static int __devexit dw_wdt_drv_remove(struct platform_device *pdev)
341 misc_deregister(&dw_wdt_miscdev);
343 clk_disable(dw_wdt.clk);
344 clk_put(dw_wdt.clk);
346 return 0;
349 static struct platform_driver dw_wdt_driver = {
350 .probe = dw_wdt_drv_probe,
351 .remove = __devexit_p(dw_wdt_drv_remove),
352 .driver = {
353 .name = "dw_wdt",
354 .owner = THIS_MODULE,
355 #ifdef CONFIG_PM
356 .pm = &dw_wdt_pm_ops,
357 #endif /* CONFIG_PM */
361 static int __init dw_wdt_watchdog_init(void)
363 return platform_driver_register(&dw_wdt_driver);
365 module_init(dw_wdt_watchdog_init);
367 static void __exit dw_wdt_watchdog_exit(void)
369 platform_driver_unregister(&dw_wdt_driver);
371 module_exit(dw_wdt_watchdog_exit);
373 MODULE_AUTHOR("Jamie Iles");
374 MODULE_DESCRIPTION("Synopsys DesignWare Watchdog Driver");
375 MODULE_LICENSE("GPL");
376 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);