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c9353ae1 JI |
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 | ||
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) ")"); | |
52 | ||
53 | #define WDT_TIMEOUT (HZ / 2) | |
54 | ||
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; | |
64 | ||
65 | static 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 | ||
71 | static 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 | ||
80 | static 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 | ||
87 | static inline void dw_wdt_set_next_heartbeat(void) | |
88 | { | |
89 | dw_wdt.next_heartbeat = jiffies + dw_wdt_get_top() * HZ; | |
90 | } | |
91 | ||
92 | static 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 | ||
114 | static void dw_wdt_keepalive(void) | |
115 | { | |
116 | writel(WDOG_COUNTER_RESTART_KICK_VALUE, dw_wdt.regs + | |
117 | WDOG_COUNTER_RESTART_REG_OFFSET); | |
118 | } | |
119 | ||
120 | static 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 | ||
130 | static 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 | ||
156 | ssize_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 | ||
186 | static 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 | ||
192 | static const struct watchdog_info dw_wdt_ident = { | |
193 | .options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT | | |
194 | WDIOF_MAGICCLOSE, | |
195 | .identity = "Synopsys DesignWare Watchdog", | |
196 | }; | |
197 | ||
198 | static 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 | ||
236 | static 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 | |
255 | static int dw_wdt_suspend(struct device *dev) | |
256 | { | |
257 | clk_disable(dw_wdt.clk); | |
258 | ||
259 | return 0; | |
260 | } | |
261 | ||
262 | static 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 | ||
274 | static 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 | ||
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 | |
287 | }; | |
288 | ||
289 | static struct miscdevice dw_wdt_miscdev = { | |
290 | .fops = &wdt_fops, | |
291 | .name = "watchdog", | |
292 | .minor = WATCHDOG_MINOR, | |
293 | }; | |
294 | ||
295 | static 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 | ||
331 | out_disable_clk: | |
332 | clk_disable(dw_wdt.clk); | |
333 | out_put_clk: | |
334 | clk_put(dw_wdt.clk); | |
335 | ||
336 | return ret; | |
337 | } | |
338 | ||
339 | static 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 | ||
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 */ | |
358 | }, | |
359 | }; | |
360 | ||
361 | static int __init dw_wdt_watchdog_init(void) | |
362 | { | |
363 | return platform_driver_register(&dw_wdt_driver); | |
364 | } | |
365 | module_init(dw_wdt_watchdog_init); | |
366 | ||
367 | static void __exit dw_wdt_watchdog_exit(void) | |
368 | { | |
369 | platform_driver_unregister(&dw_wdt_driver); | |
370 | } | |
371 | module_exit(dw_wdt_watchdog_exit); | |
372 | ||
373 | MODULE_AUTHOR("Jamie Iles"); | |
374 | MODULE_DESCRIPTION("Synopsys DesignWare Watchdog Driver"); | |
375 | MODULE_LICENSE("GPL"); | |
376 | MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR); |