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1/*
2 * Copyright 2010-2011 Picochip Ltd., Jamie Iles
3 * http://www.picochip.com
4 *
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.
9 *
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.
13 *
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.
18 */
19#define pr_fmt(fmt) "dw_wdt: " fmt
20
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>
37
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
44
45/* The maximum TOP (timeout period) value that can be set in the watchdog. */
46#define DW_WDT_MAX_TOP 15
47
48static int nowayout = WATCHDOG_NOWAYOUT;
49module_param(nowayout, int, 0);
50MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started "
51 "(default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
52
53#define WDT_TIMEOUT (HZ / 2)
54
55static 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;
64
65static inline int dw_wdt_is_enabled(void)
66{
67 return readl(dw_wdt.regs + WDOG_CONTROL_REG_OFFSET) &
68 WDOG_CONTROL_REG_WDT_EN_MASK;
69}
70
71static inline int dw_wdt_top_in_seconds(unsigned top)
72{
73 /*
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.
76 */
77 return (1 << (16 + top)) / clk_get_rate(dw_wdt.clk);
78}
79
80static int dw_wdt_get_top(void)
81{
82 int top = readl(dw_wdt.regs + WDOG_TIMEOUT_RANGE_REG_OFFSET) & 0xF;
83
84 return dw_wdt_top_in_seconds(top);
85}
86
87static inline void dw_wdt_set_next_heartbeat(void)
88{
89 dw_wdt.next_heartbeat = jiffies + dw_wdt_get_top() * HZ;
90}
91
92static int dw_wdt_set_top(unsigned top_s)
93{
94 int i, top_val = DW_WDT_MAX_TOP;
95
96 /*
97 * Iterate over the timeout values until we find the closest match. We
98 * always look for >=.
99 */
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;
104 }
105
106 /* Set the new value in the watchdog. */
107 writel(top_val, dw_wdt.regs + WDOG_TIMEOUT_RANGE_REG_OFFSET);
108
109 dw_wdt_set_next_heartbeat();
110
111 return dw_wdt_top_in_seconds(top_val);
112}
113
114static void dw_wdt_keepalive(void)
115{
116 writel(WDOG_COUNTER_RESTART_KICK_VALUE, dw_wdt.regs +
117 WDOG_COUNTER_RESTART_REG_OFFSET);
118}
119
120static void dw_wdt_ping(unsigned long data)
121{
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");
128}
129
130static int dw_wdt_open(struct inode *inode, struct file *filp)
131{
132 if (test_and_set_bit(0, &dw_wdt.in_use))
133 return -EBUSY;
134
135 /* Make sure we don't get unloaded. */
136 __module_get(THIS_MODULE);
137
138 spin_lock(&dw_wdt.lock);
139 if (!dw_wdt_is_enabled()) {
140 /*
141 * The watchdog is not currently enabled. Set the timeout to
142 * the maximum and then start it.
143 */
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);
147 }
148
149 dw_wdt_set_next_heartbeat();
150
151 spin_unlock(&dw_wdt.lock);
152
153 return nonseekable_open(inode, filp);
154}
155
156ssize_t dw_wdt_write(struct file *filp, const char __user *buf, size_t len,
157 loff_t *offset)
158{
159 if (!len)
160 return 0;
161
162 if (!nowayout) {
163 size_t i;
164
165 dw_wdt.expect_close = 0;
166
167 for (i = 0; i < len; ++i) {
168 char c;
169
170 if (get_user(c, buf + i))
171 return -EFAULT;
172
173 if (c == 'V') {
174 dw_wdt.expect_close = 1;
175 break;
176 }
177 }
178 }
179
180 dw_wdt_set_next_heartbeat();
181 mod_timer(&dw_wdt.timer, jiffies + WDT_TIMEOUT);
182
183 return len;
184}
185
186static u32 dw_wdt_time_left(void)
187{
188 return readl(dw_wdt.regs + WDOG_CURRENT_COUNT_REG_OFFSET) /
189 clk_get_rate(dw_wdt.clk);
190}
191
192static const struct watchdog_info dw_wdt_ident = {
193 .options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT |
194 WDIOF_MAGICCLOSE,
195 .identity = "Synopsys DesignWare Watchdog",
196};
197
198static long dw_wdt_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
199{
200 unsigned long val;
201 int timeout;
202
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;
207
208 case WDIOC_GETSTATUS:
209 case WDIOC_GETBOOTSTATUS:
210 return put_user(0, (int *)arg);
211
212 case WDIOC_KEEPALIVE:
213 dw_wdt_set_next_heartbeat();
214 return 0;
215
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);
221
222 case WDIOC_GETTIMEOUT:
223 return put_user(dw_wdt_get_top(), (int __user *)arg);
224
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);
230
231 default:
232 return -ENOTTY;
233 }
234}
235
236static int dw_wdt_release(struct inode *inode, struct file *filp)
237{
238 clear_bit(0, &dw_wdt.in_use);
239
240 if (!dw_wdt.expect_close) {
241 del_timer(&dw_wdt.timer);
242
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");
247 }
248
249 dw_wdt.expect_close = 0;
250
251 return 0;
252}
253
254#ifdef CONFIG_PM
255static int dw_wdt_suspend(struct device *dev)
256{
257 clk_disable(dw_wdt.clk);
258
259 return 0;
260}
261
262static int dw_wdt_resume(struct device *dev)
263{
264 int err = clk_enable(dw_wdt.clk);
265
266 if (err)
267 return err;
268
269 dw_wdt_keepalive();
270
271 return 0;
272}
273
274static const struct dev_pm_ops dw_wdt_pm_ops = {
275 .suspend = dw_wdt_suspend,
276 .resume = dw_wdt_resume,
277};
278#endif /* CONFIG_PM */
279
280static 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
287};
288
289static struct miscdevice dw_wdt_miscdev = {
290 .fops = &wdt_fops,
291 .name = "watchdog",
292 .minor = WATCHDOG_MINOR,
293};
294
295static int __devinit dw_wdt_drv_probe(struct platform_device *pdev)
296{
297 int ret;
298 struct resource *mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
299
300 if (!mem)
301 return -EINVAL;
302
303 if (!devm_request_mem_region(&pdev->dev, mem->start, resource_size(mem),
304 "dw_wdt"))
305 return -ENOMEM;
306
307 dw_wdt.regs = devm_ioremap(&pdev->dev, mem->start, resource_size(mem));
308 if (!dw_wdt.regs)
309 return -ENOMEM;
310
311 dw_wdt.clk = clk_get(&pdev->dev, NULL);
312 if (IS_ERR(dw_wdt.clk))
313 return PTR_ERR(dw_wdt.clk);
314
315 ret = clk_enable(dw_wdt.clk);
316 if (ret)
317 goto out_put_clk;
318
319 spin_lock_init(&dw_wdt.lock);
320
321 ret = misc_register(&dw_wdt_miscdev);
322 if (ret)
323 goto out_disable_clk;
324
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);
328
329 return 0;
330
331out_disable_clk:
332 clk_disable(dw_wdt.clk);
333out_put_clk:
334 clk_put(dw_wdt.clk);
335
336 return ret;
337}
338
339static int __devexit dw_wdt_drv_remove(struct platform_device *pdev)
340{
341 misc_deregister(&dw_wdt_miscdev);
342
343 clk_disable(dw_wdt.clk);
344 clk_put(dw_wdt.clk);
345
346 return 0;
347}
348
349static 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 */
358 },
359};
360
361static int __init dw_wdt_watchdog_init(void)
362{
363 return platform_driver_register(&dw_wdt_driver);
364}
365module_init(dw_wdt_watchdog_init);
366
367static void __exit dw_wdt_watchdog_exit(void)
368{
369 platform_driver_unregister(&dw_wdt_driver);
370}
371module_exit(dw_wdt_watchdog_exit);
372
373MODULE_AUTHOR("Jamie Iles");
374MODULE_DESCRIPTION("Synopsys DesignWare Watchdog Driver");
375MODULE_LICENSE("GPL");
376MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
1/*
2 * Copyright 2010-2011 Picochip Ltd., Jamie Iles
3 * http://www.picochip.com
4 *
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.
9 *
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.
13 *
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.
18 */
19
20#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
21
22#include <linux/bitops.h>
23#include <linux/clk.h>
24#include <linux/device.h>
25#include <linux/err.h>
26#include <linux/fs.h>
27#include <linux/io.h>
28#include <linux/kernel.h>
29#include <linux/miscdevice.h>
30#include <linux/module.h>
31#include <linux/moduleparam.h>
32#include <linux/pm.h>
33#include <linux/platform_device.h>
34#include <linux/spinlock.h>
35#include <linux/timer.h>
36#include <linux/uaccess.h>
37#include <linux/watchdog.h>
38
39#define WDOG_CONTROL_REG_OFFSET 0x00
40#define WDOG_CONTROL_REG_WDT_EN_MASK 0x01
41#define WDOG_TIMEOUT_RANGE_REG_OFFSET 0x04
42#define WDOG_CURRENT_COUNT_REG_OFFSET 0x08
43#define WDOG_COUNTER_RESTART_REG_OFFSET 0x0c
44#define WDOG_COUNTER_RESTART_KICK_VALUE 0x76
45
46/* The maximum TOP (timeout period) value that can be set in the watchdog. */
47#define DW_WDT_MAX_TOP 15
48
49static bool nowayout = WATCHDOG_NOWAYOUT;
50module_param(nowayout, bool, 0);
51MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started "
52 "(default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
53
54#define WDT_TIMEOUT (HZ / 2)
55
56static struct {
57 spinlock_t lock;
58 void __iomem *regs;
59 struct clk *clk;
60 unsigned long in_use;
61 unsigned long next_heartbeat;
62 struct timer_list timer;
63 int expect_close;
64} dw_wdt;
65
66static inline int dw_wdt_is_enabled(void)
67{
68 return readl(dw_wdt.regs + WDOG_CONTROL_REG_OFFSET) &
69 WDOG_CONTROL_REG_WDT_EN_MASK;
70}
71
72static inline int dw_wdt_top_in_seconds(unsigned top)
73{
74 /*
75 * There are 16 possible timeout values in 0..15 where the number of
76 * cycles is 2 ^ (16 + i) and the watchdog counts down.
77 */
78 return (1 << (16 + top)) / clk_get_rate(dw_wdt.clk);
79}
80
81static int dw_wdt_get_top(void)
82{
83 int top = readl(dw_wdt.regs + WDOG_TIMEOUT_RANGE_REG_OFFSET) & 0xF;
84
85 return dw_wdt_top_in_seconds(top);
86}
87
88static inline void dw_wdt_set_next_heartbeat(void)
89{
90 dw_wdt.next_heartbeat = jiffies + dw_wdt_get_top() * HZ;
91}
92
93static int dw_wdt_set_top(unsigned top_s)
94{
95 int i, top_val = DW_WDT_MAX_TOP;
96
97 /*
98 * Iterate over the timeout values until we find the closest match. We
99 * always look for >=.
100 */
101 for (i = 0; i <= DW_WDT_MAX_TOP; ++i)
102 if (dw_wdt_top_in_seconds(i) >= top_s) {
103 top_val = i;
104 break;
105 }
106
107 /* Set the new value in the watchdog. */
108 writel(top_val, dw_wdt.regs + WDOG_TIMEOUT_RANGE_REG_OFFSET);
109
110 dw_wdt_set_next_heartbeat();
111
112 return dw_wdt_top_in_seconds(top_val);
113}
114
115static void dw_wdt_keepalive(void)
116{
117 writel(WDOG_COUNTER_RESTART_KICK_VALUE, dw_wdt.regs +
118 WDOG_COUNTER_RESTART_REG_OFFSET);
119}
120
121static void dw_wdt_ping(unsigned long data)
122{
123 if (time_before(jiffies, dw_wdt.next_heartbeat) ||
124 (!nowayout && !dw_wdt.in_use)) {
125 dw_wdt_keepalive();
126 mod_timer(&dw_wdt.timer, jiffies + WDT_TIMEOUT);
127 } else
128 pr_crit("keepalive missed, machine will reset\n");
129}
130
131static int dw_wdt_open(struct inode *inode, struct file *filp)
132{
133 if (test_and_set_bit(0, &dw_wdt.in_use))
134 return -EBUSY;
135
136 /* Make sure we don't get unloaded. */
137 __module_get(THIS_MODULE);
138
139 spin_lock(&dw_wdt.lock);
140 if (!dw_wdt_is_enabled()) {
141 /*
142 * The watchdog is not currently enabled. Set the timeout to
143 * the maximum and then start it.
144 */
145 dw_wdt_set_top(DW_WDT_MAX_TOP);
146 writel(WDOG_CONTROL_REG_WDT_EN_MASK,
147 dw_wdt.regs + WDOG_CONTROL_REG_OFFSET);
148 }
149
150 dw_wdt_set_next_heartbeat();
151
152 spin_unlock(&dw_wdt.lock);
153
154 return nonseekable_open(inode, filp);
155}
156
157ssize_t dw_wdt_write(struct file *filp, const char __user *buf, size_t len,
158 loff_t *offset)
159{
160 if (!len)
161 return 0;
162
163 if (!nowayout) {
164 size_t i;
165
166 dw_wdt.expect_close = 0;
167
168 for (i = 0; i < len; ++i) {
169 char c;
170
171 if (get_user(c, buf + i))
172 return -EFAULT;
173
174 if (c == 'V') {
175 dw_wdt.expect_close = 1;
176 break;
177 }
178 }
179 }
180
181 dw_wdt_set_next_heartbeat();
182 mod_timer(&dw_wdt.timer, jiffies + WDT_TIMEOUT);
183
184 return len;
185}
186
187static u32 dw_wdt_time_left(void)
188{
189 return readl(dw_wdt.regs + WDOG_CURRENT_COUNT_REG_OFFSET) /
190 clk_get_rate(dw_wdt.clk);
191}
192
193static const struct watchdog_info dw_wdt_ident = {
194 .options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT |
195 WDIOF_MAGICCLOSE,
196 .identity = "Synopsys DesignWare Watchdog",
197};
198
199static long dw_wdt_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
200{
201 unsigned long val;
202 int timeout;
203
204 switch (cmd) {
205 case WDIOC_GETSUPPORT:
206 return copy_to_user((struct watchdog_info *)arg, &dw_wdt_ident,
207 sizeof(dw_wdt_ident)) ? -EFAULT : 0;
208
209 case WDIOC_GETSTATUS:
210 case WDIOC_GETBOOTSTATUS:
211 return put_user(0, (int *)arg);
212
213 case WDIOC_KEEPALIVE:
214 dw_wdt_set_next_heartbeat();
215 return 0;
216
217 case WDIOC_SETTIMEOUT:
218 if (get_user(val, (int __user *)arg))
219 return -EFAULT;
220 timeout = dw_wdt_set_top(val);
221 return put_user(timeout , (int __user *)arg);
222
223 case WDIOC_GETTIMEOUT:
224 return put_user(dw_wdt_get_top(), (int __user *)arg);
225
226 case WDIOC_GETTIMELEFT:
227 /* Get the time left until expiry. */
228 if (get_user(val, (int __user *)arg))
229 return -EFAULT;
230 return put_user(dw_wdt_time_left(), (int __user *)arg);
231
232 default:
233 return -ENOTTY;
234 }
235}
236
237static int dw_wdt_release(struct inode *inode, struct file *filp)
238{
239 clear_bit(0, &dw_wdt.in_use);
240
241 if (!dw_wdt.expect_close) {
242 del_timer(&dw_wdt.timer);
243
244 if (!nowayout)
245 pr_crit("unexpected close, system will reboot soon\n");
246 else
247 pr_crit("watchdog cannot be disabled, system will reboot soon\n");
248 }
249
250 dw_wdt.expect_close = 0;
251
252 return 0;
253}
254
255#ifdef CONFIG_PM
256static int dw_wdt_suspend(struct device *dev)
257{
258 clk_disable(dw_wdt.clk);
259
260 return 0;
261}
262
263static int dw_wdt_resume(struct device *dev)
264{
265 int err = clk_enable(dw_wdt.clk);
266
267 if (err)
268 return err;
269
270 dw_wdt_keepalive();
271
272 return 0;
273}
274
275static const struct dev_pm_ops dw_wdt_pm_ops = {
276 .suspend = dw_wdt_suspend,
277 .resume = dw_wdt_resume,
278};
279#endif /* CONFIG_PM */
280
281static const struct file_operations wdt_fops = {
282 .owner = THIS_MODULE,
283 .llseek = no_llseek,
284 .open = dw_wdt_open,
285 .write = dw_wdt_write,
286 .unlocked_ioctl = dw_wdt_ioctl,
287 .release = dw_wdt_release
288};
289
290static struct miscdevice dw_wdt_miscdev = {
291 .fops = &wdt_fops,
292 .name = "watchdog",
293 .minor = WATCHDOG_MINOR,
294};
295
296static int __devinit dw_wdt_drv_probe(struct platform_device *pdev)
297{
298 int ret;
299 struct resource *mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
300
301 if (!mem)
302 return -EINVAL;
303
304 dw_wdt.regs = devm_request_and_ioremap(&pdev->dev, mem);
305 if (!dw_wdt.regs)
306 return -ENOMEM;
307
308 dw_wdt.clk = clk_get(&pdev->dev, NULL);
309 if (IS_ERR(dw_wdt.clk))
310 return PTR_ERR(dw_wdt.clk);
311
312 ret = clk_enable(dw_wdt.clk);
313 if (ret)
314 goto out_put_clk;
315
316 spin_lock_init(&dw_wdt.lock);
317
318 ret = misc_register(&dw_wdt_miscdev);
319 if (ret)
320 goto out_disable_clk;
321
322 dw_wdt_set_next_heartbeat();
323 setup_timer(&dw_wdt.timer, dw_wdt_ping, 0);
324 mod_timer(&dw_wdt.timer, jiffies + WDT_TIMEOUT);
325
326 return 0;
327
328out_disable_clk:
329 clk_disable(dw_wdt.clk);
330out_put_clk:
331 clk_put(dw_wdt.clk);
332
333 return ret;
334}
335
336static int __devexit dw_wdt_drv_remove(struct platform_device *pdev)
337{
338 misc_deregister(&dw_wdt_miscdev);
339
340 clk_disable(dw_wdt.clk);
341 clk_put(dw_wdt.clk);
342
343 return 0;
344}
345
346static struct platform_driver dw_wdt_driver = {
347 .probe = dw_wdt_drv_probe,
348 .remove = __devexit_p(dw_wdt_drv_remove),
349 .driver = {
350 .name = "dw_wdt",
351 .owner = THIS_MODULE,
352#ifdef CONFIG_PM
353 .pm = &dw_wdt_pm_ops,
354#endif /* CONFIG_PM */
355 },
356};
357
358module_platform_driver(dw_wdt_driver);
359
360MODULE_AUTHOR("Jamie Iles");
361MODULE_DESCRIPTION("Synopsys DesignWare Watchdog Driver");
362MODULE_LICENSE("GPL");
363MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);