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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 | |
58a251f2 | 11 | * in the many subsystems. The watchdog has 16 different timeout periods |
c9353ae1 JI |
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 | */ | |
27c766aa JP |
19 | |
20 | #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt | |
c9353ae1 JI |
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> | |
58e56373 | 32 | #include <linux/of.h> |
c9353ae1 JI |
33 | #include <linux/pm.h> |
34 | #include <linux/platform_device.h> | |
35 | #include <linux/spinlock.h> | |
36 | #include <linux/timer.h> | |
37 | #include <linux/uaccess.h> | |
38 | #include <linux/watchdog.h> | |
39 | ||
40 | #define WDOG_CONTROL_REG_OFFSET 0x00 | |
41 | #define WDOG_CONTROL_REG_WDT_EN_MASK 0x01 | |
42 | #define WDOG_TIMEOUT_RANGE_REG_OFFSET 0x04 | |
43 | #define WDOG_CURRENT_COUNT_REG_OFFSET 0x08 | |
44 | #define WDOG_COUNTER_RESTART_REG_OFFSET 0x0c | |
45 | #define WDOG_COUNTER_RESTART_KICK_VALUE 0x76 | |
46 | ||
47 | /* The maximum TOP (timeout period) value that can be set in the watchdog. */ | |
48 | #define DW_WDT_MAX_TOP 15 | |
49 | ||
86a1e189 WVS |
50 | static bool nowayout = WATCHDOG_NOWAYOUT; |
51 | module_param(nowayout, bool, 0); | |
c9353ae1 JI |
52 | MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started " |
53 | "(default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")"); | |
54 | ||
55 | #define WDT_TIMEOUT (HZ / 2) | |
56 | ||
57 | static struct { | |
58 | spinlock_t lock; | |
59 | void __iomem *regs; | |
60 | struct clk *clk; | |
61 | unsigned long in_use; | |
62 | unsigned long next_heartbeat; | |
63 | struct timer_list timer; | |
64 | int expect_close; | |
65 | } dw_wdt; | |
66 | ||
67 | static inline int dw_wdt_is_enabled(void) | |
68 | { | |
69 | return readl(dw_wdt.regs + WDOG_CONTROL_REG_OFFSET) & | |
70 | WDOG_CONTROL_REG_WDT_EN_MASK; | |
71 | } | |
72 | ||
73 | static inline int dw_wdt_top_in_seconds(unsigned top) | |
74 | { | |
75 | /* | |
76 | * There are 16 possible timeout values in 0..15 where the number of | |
77 | * cycles is 2 ^ (16 + i) and the watchdog counts down. | |
78 | */ | |
79 | return (1 << (16 + top)) / clk_get_rate(dw_wdt.clk); | |
80 | } | |
81 | ||
82 | static int dw_wdt_get_top(void) | |
83 | { | |
84 | int top = readl(dw_wdt.regs + WDOG_TIMEOUT_RANGE_REG_OFFSET) & 0xF; | |
85 | ||
86 | return dw_wdt_top_in_seconds(top); | |
87 | } | |
88 | ||
89 | static inline void dw_wdt_set_next_heartbeat(void) | |
90 | { | |
91 | dw_wdt.next_heartbeat = jiffies + dw_wdt_get_top() * HZ; | |
92 | } | |
93 | ||
94 | static int dw_wdt_set_top(unsigned top_s) | |
95 | { | |
96 | int i, top_val = DW_WDT_MAX_TOP; | |
97 | ||
98 | /* | |
99 | * Iterate over the timeout values until we find the closest match. We | |
100 | * always look for >=. | |
101 | */ | |
102 | for (i = 0; i <= DW_WDT_MAX_TOP; ++i) | |
103 | if (dw_wdt_top_in_seconds(i) >= top_s) { | |
104 | top_val = i; | |
105 | break; | |
106 | } | |
107 | ||
108 | /* Set the new value in the watchdog. */ | |
109 | writel(top_val, dw_wdt.regs + WDOG_TIMEOUT_RANGE_REG_OFFSET); | |
110 | ||
111 | dw_wdt_set_next_heartbeat(); | |
112 | ||
113 | return dw_wdt_top_in_seconds(top_val); | |
114 | } | |
115 | ||
116 | static void dw_wdt_keepalive(void) | |
117 | { | |
118 | writel(WDOG_COUNTER_RESTART_KICK_VALUE, dw_wdt.regs + | |
119 | WDOG_COUNTER_RESTART_REG_OFFSET); | |
120 | } | |
121 | ||
122 | static void dw_wdt_ping(unsigned long data) | |
123 | { | |
124 | if (time_before(jiffies, dw_wdt.next_heartbeat) || | |
125 | (!nowayout && !dw_wdt.in_use)) { | |
126 | dw_wdt_keepalive(); | |
127 | mod_timer(&dw_wdt.timer, jiffies + WDT_TIMEOUT); | |
128 | } else | |
129 | pr_crit("keepalive missed, machine will reset\n"); | |
130 | } | |
131 | ||
132 | static int dw_wdt_open(struct inode *inode, struct file *filp) | |
133 | { | |
134 | if (test_and_set_bit(0, &dw_wdt.in_use)) | |
135 | return -EBUSY; | |
136 | ||
137 | /* Make sure we don't get unloaded. */ | |
138 | __module_get(THIS_MODULE); | |
139 | ||
140 | spin_lock(&dw_wdt.lock); | |
141 | if (!dw_wdt_is_enabled()) { | |
142 | /* | |
143 | * The watchdog is not currently enabled. Set the timeout to | |
144 | * the maximum and then start it. | |
145 | */ | |
146 | dw_wdt_set_top(DW_WDT_MAX_TOP); | |
147 | writel(WDOG_CONTROL_REG_WDT_EN_MASK, | |
148 | dw_wdt.regs + WDOG_CONTROL_REG_OFFSET); | |
149 | } | |
150 | ||
151 | dw_wdt_set_next_heartbeat(); | |
152 | ||
153 | spin_unlock(&dw_wdt.lock); | |
154 | ||
155 | return nonseekable_open(inode, filp); | |
156 | } | |
157 | ||
0b930261 SK |
158 | static ssize_t dw_wdt_write(struct file *filp, const char __user *buf, |
159 | size_t len, loff_t *offset) | |
c9353ae1 JI |
160 | { |
161 | if (!len) | |
162 | return 0; | |
163 | ||
164 | if (!nowayout) { | |
165 | size_t i; | |
166 | ||
167 | dw_wdt.expect_close = 0; | |
168 | ||
169 | for (i = 0; i < len; ++i) { | |
170 | char c; | |
171 | ||
172 | if (get_user(c, buf + i)) | |
173 | return -EFAULT; | |
174 | ||
175 | if (c == 'V') { | |
176 | dw_wdt.expect_close = 1; | |
177 | break; | |
178 | } | |
179 | } | |
180 | } | |
181 | ||
182 | dw_wdt_set_next_heartbeat(); | |
183 | mod_timer(&dw_wdt.timer, jiffies + WDT_TIMEOUT); | |
184 | ||
185 | return len; | |
186 | } | |
187 | ||
188 | static u32 dw_wdt_time_left(void) | |
189 | { | |
190 | return readl(dw_wdt.regs + WDOG_CURRENT_COUNT_REG_OFFSET) / | |
191 | clk_get_rate(dw_wdt.clk); | |
192 | } | |
193 | ||
194 | static const struct watchdog_info dw_wdt_ident = { | |
195 | .options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT | | |
196 | WDIOF_MAGICCLOSE, | |
197 | .identity = "Synopsys DesignWare Watchdog", | |
198 | }; | |
199 | ||
200 | static long dw_wdt_ioctl(struct file *filp, unsigned int cmd, unsigned long arg) | |
201 | { | |
202 | unsigned long val; | |
203 | int timeout; | |
204 | ||
205 | switch (cmd) { | |
206 | case WDIOC_GETSUPPORT: | |
60295507 | 207 | return copy_to_user((void __user *)arg, &dw_wdt_ident, |
c9353ae1 JI |
208 | sizeof(dw_wdt_ident)) ? -EFAULT : 0; |
209 | ||
210 | case WDIOC_GETSTATUS: | |
211 | case WDIOC_GETBOOTSTATUS: | |
60295507 | 212 | return put_user(0, (int __user *)arg); |
c9353ae1 JI |
213 | |
214 | case WDIOC_KEEPALIVE: | |
215 | dw_wdt_set_next_heartbeat(); | |
216 | return 0; | |
217 | ||
218 | case WDIOC_SETTIMEOUT: | |
219 | if (get_user(val, (int __user *)arg)) | |
220 | return -EFAULT; | |
221 | timeout = dw_wdt_set_top(val); | |
222 | return put_user(timeout , (int __user *)arg); | |
223 | ||
224 | case WDIOC_GETTIMEOUT: | |
225 | return put_user(dw_wdt_get_top(), (int __user *)arg); | |
226 | ||
227 | case WDIOC_GETTIMELEFT: | |
228 | /* Get the time left until expiry. */ | |
229 | if (get_user(val, (int __user *)arg)) | |
230 | return -EFAULT; | |
231 | return put_user(dw_wdt_time_left(), (int __user *)arg); | |
232 | ||
233 | default: | |
234 | return -ENOTTY; | |
235 | } | |
236 | } | |
237 | ||
238 | static int dw_wdt_release(struct inode *inode, struct file *filp) | |
239 | { | |
240 | clear_bit(0, &dw_wdt.in_use); | |
241 | ||
242 | if (!dw_wdt.expect_close) { | |
243 | del_timer(&dw_wdt.timer); | |
244 | ||
245 | if (!nowayout) | |
246 | pr_crit("unexpected close, system will reboot soon\n"); | |
247 | else | |
248 | pr_crit("watchdog cannot be disabled, system will reboot soon\n"); | |
249 | } | |
250 | ||
251 | dw_wdt.expect_close = 0; | |
252 | ||
253 | return 0; | |
254 | } | |
255 | ||
ad83c6cb | 256 | #ifdef CONFIG_PM_SLEEP |
c9353ae1 JI |
257 | static int dw_wdt_suspend(struct device *dev) |
258 | { | |
280103e6 | 259 | clk_disable_unprepare(dw_wdt.clk); |
c9353ae1 JI |
260 | |
261 | return 0; | |
262 | } | |
263 | ||
264 | static int dw_wdt_resume(struct device *dev) | |
265 | { | |
280103e6 | 266 | int err = clk_prepare_enable(dw_wdt.clk); |
c9353ae1 JI |
267 | |
268 | if (err) | |
269 | return err; | |
270 | ||
271 | dw_wdt_keepalive(); | |
272 | ||
273 | return 0; | |
274 | } | |
ad83c6cb | 275 | #endif /* CONFIG_PM_SLEEP */ |
c9353ae1 | 276 | |
ad83c6cb | 277 | static SIMPLE_DEV_PM_OPS(dw_wdt_pm_ops, dw_wdt_suspend, dw_wdt_resume); |
c9353ae1 JI |
278 | |
279 | static const struct file_operations wdt_fops = { | |
280 | .owner = THIS_MODULE, | |
281 | .llseek = no_llseek, | |
282 | .open = dw_wdt_open, | |
283 | .write = dw_wdt_write, | |
284 | .unlocked_ioctl = dw_wdt_ioctl, | |
285 | .release = dw_wdt_release | |
286 | }; | |
287 | ||
288 | static struct miscdevice dw_wdt_miscdev = { | |
289 | .fops = &wdt_fops, | |
290 | .name = "watchdog", | |
291 | .minor = WATCHDOG_MINOR, | |
292 | }; | |
293 | ||
2d991a16 | 294 | static int dw_wdt_drv_probe(struct platform_device *pdev) |
c9353ae1 JI |
295 | { |
296 | int ret; | |
297 | struct resource *mem = platform_get_resource(pdev, IORESOURCE_MEM, 0); | |
298 | ||
4c271bb6 TR |
299 | dw_wdt.regs = devm_ioremap_resource(&pdev->dev, mem); |
300 | if (IS_ERR(dw_wdt.regs)) | |
301 | return PTR_ERR(dw_wdt.regs); | |
c9353ae1 | 302 | |
cf3cc8c2 | 303 | dw_wdt.clk = devm_clk_get(&pdev->dev, NULL); |
c9353ae1 JI |
304 | if (IS_ERR(dw_wdt.clk)) |
305 | return PTR_ERR(dw_wdt.clk); | |
306 | ||
280103e6 | 307 | ret = clk_prepare_enable(dw_wdt.clk); |
c9353ae1 | 308 | if (ret) |
cf3cc8c2 | 309 | return ret; |
c9353ae1 JI |
310 | |
311 | spin_lock_init(&dw_wdt.lock); | |
312 | ||
313 | ret = misc_register(&dw_wdt_miscdev); | |
314 | if (ret) | |
315 | goto out_disable_clk; | |
316 | ||
317 | dw_wdt_set_next_heartbeat(); | |
318 | setup_timer(&dw_wdt.timer, dw_wdt_ping, 0); | |
319 | mod_timer(&dw_wdt.timer, jiffies + WDT_TIMEOUT); | |
320 | ||
321 | return 0; | |
322 | ||
323 | out_disable_clk: | |
280103e6 | 324 | clk_disable_unprepare(dw_wdt.clk); |
c9353ae1 JI |
325 | |
326 | return ret; | |
327 | } | |
328 | ||
4b12b896 | 329 | static int dw_wdt_drv_remove(struct platform_device *pdev) |
c9353ae1 JI |
330 | { |
331 | misc_deregister(&dw_wdt_miscdev); | |
332 | ||
280103e6 | 333 | clk_disable_unprepare(dw_wdt.clk); |
c9353ae1 JI |
334 | |
335 | return 0; | |
336 | } | |
337 | ||
58e56373 DN |
338 | #ifdef CONFIG_OF |
339 | static const struct of_device_id dw_wdt_of_match[] = { | |
340 | { .compatible = "snps,dw-wdt", }, | |
341 | { /* sentinel */ } | |
342 | }; | |
343 | MODULE_DEVICE_TABLE(of, dw_wdt_of_match); | |
344 | #endif | |
345 | ||
c9353ae1 JI |
346 | static struct platform_driver dw_wdt_driver = { |
347 | .probe = dw_wdt_drv_probe, | |
82268714 | 348 | .remove = dw_wdt_drv_remove, |
c9353ae1 JI |
349 | .driver = { |
350 | .name = "dw_wdt", | |
351 | .owner = THIS_MODULE, | |
58e56373 | 352 | .of_match_table = of_match_ptr(dw_wdt_of_match), |
c9353ae1 | 353 | .pm = &dw_wdt_pm_ops, |
c9353ae1 JI |
354 | }, |
355 | }; | |
356 | ||
b8ec6118 | 357 | module_platform_driver(dw_wdt_driver); |
c9353ae1 JI |
358 | |
359 | MODULE_AUTHOR("Jamie Iles"); | |
360 | MODULE_DESCRIPTION("Synopsys DesignWare Watchdog Driver"); | |
361 | MODULE_LICENSE("GPL"); |