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1 | /* |
2 | * Watchdog driver for Atmel AT32AP700X devices |
3 | * |
4 | * Copyright (C) 2005-2006 Atmel Corporation |
5 | * |
6 | * This program is free software; you can redistribute it and/or modify |
7 | * it under the terms of the GNU General Public License version 2 as |
8 | * published by the Free Software Foundation. |
9 | * |
10 | * |
11 | * Errata: WDT Clear is blocked after WDT Reset |
12 | * |
13 | * A watchdog timer event will, after reset, block writes to the WDT_CLEAR |
14 | * register, preventing the program to clear the next Watchdog Timer Reset. |
15 | * |
16 | * If you still want to use the WDT after a WDT reset a small code can be |
17 | * insterted at the startup checking the AVR32_PM.rcause register for WDT reset |
18 | * and use a GPIO pin to reset the system. This method requires that one of the |
19 | * GPIO pins are available and connected externally to the RESET_N pin. After |
20 | * the GPIO pin has pulled down the reset line the GPIO will be reset and leave |
21 | * the pin tristated with pullup. |
22 | */ |
23 | |
24 | #include <linux/init.h> |
25 | #include <linux/kernel.h> |
26 | #include <linux/module.h> |
27 | #include <linux/moduleparam.h> |
28 | #include <linux/miscdevice.h> |
29 | #include <linux/fs.h> |
30 | #include <linux/platform_device.h> |
31 | #include <linux/watchdog.h> |
32 | #include <linux/uaccess.h> |
33 | #include <linux/io.h> |
34 | #include <linux/spinlock.h> |
35 | #include <linux/slab.h> |
36 | |
37 | #define TIMEOUT_MIN 1 |
38 | #define TIMEOUT_MAX 2 |
39 | #define TIMEOUT_DEFAULT TIMEOUT_MAX |
40 | |
41 | /* module parameters */ |
42 | static int timeout = TIMEOUT_DEFAULT; |
43 | module_param(timeout, int, 0); |
44 | MODULE_PARM_DESC(timeout, |
45 | "Timeout value. Limited to be 1 or 2 seconds. (default=" |
46 | __MODULE_STRING(TIMEOUT_DEFAULT) ")"); |
47 | |
48 | static bool nowayout = WATCHDOG_NOWAYOUT; |
49 | module_param(nowayout, bool, 0); |
50 | MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default=" |
51 | __MODULE_STRING(WATCHDOG_NOWAYOUT) ")"); |
52 | |
53 | /* Watchdog registers and write/read macro */ |
54 | #define WDT_CTRL 0x00 |
55 | #define WDT_CTRL_EN 0 |
56 | #define WDT_CTRL_PSEL 8 |
57 | #define WDT_CTRL_KEY 24 |
58 | |
59 | #define WDT_CLR 0x04 |
60 | |
61 | #define WDT_RCAUSE 0x10 |
62 | #define WDT_RCAUSE_POR 0 |
63 | #define WDT_RCAUSE_EXT 2 |
64 | #define WDT_RCAUSE_WDT 3 |
65 | #define WDT_RCAUSE_JTAG 4 |
66 | #define WDT_RCAUSE_SERP 5 |
67 | |
68 | #define WDT_BIT(name) (1 << WDT_##name) |
69 | #define WDT_BF(name, value) ((value) << WDT_##name) |
70 | |
71 | #define wdt_readl(dev, reg) \ |
72 | __raw_readl((dev)->regs + WDT_##reg) |
73 | #define wdt_writel(dev, reg, value) \ |
74 | __raw_writel((value), (dev)->regs + WDT_##reg) |
75 | |
76 | struct wdt_at32ap700x { |
77 | void __iomem *regs; |
78 | spinlock_t io_lock; |
79 | int timeout; |
80 | int boot_status; |
81 | unsigned long users; |
82 | struct miscdevice miscdev; |
83 | }; |
84 | |
85 | static struct wdt_at32ap700x *wdt; |
86 | static char expect_release; |
87 | |
88 | /* |
89 | * Disable the watchdog. |
90 | */ |
91 | static inline void at32_wdt_stop(void) |
92 | { |
93 | unsigned long psel; |
94 | |
95 | spin_lock(&wdt->io_lock); |
96 | psel = wdt_readl(wdt, CTRL) & WDT_BF(CTRL_PSEL, 0x0f); |
97 | wdt_writel(wdt, CTRL, psel | WDT_BF(CTRL_KEY, 0x55)); |
98 | wdt_writel(wdt, CTRL, psel | WDT_BF(CTRL_KEY, 0xaa)); |
99 | spin_unlock(&wdt->io_lock); |
100 | } |
101 | |
102 | /* |
103 | * Enable and reset the watchdog. |
104 | */ |
105 | static inline void at32_wdt_start(void) |
106 | { |
107 | /* 0xf is 2^16 divider = 2 sec, 0xe is 2^15 divider = 1 sec */ |
108 | unsigned long psel = (wdt->timeout > 1) ? 0xf : 0xe; |
109 | |
110 | spin_lock(&wdt->io_lock); |
111 | wdt_writel(wdt, CTRL, WDT_BIT(CTRL_EN) |
112 | | WDT_BF(CTRL_PSEL, psel) |
113 | | WDT_BF(CTRL_KEY, 0x55)); |
114 | wdt_writel(wdt, CTRL, WDT_BIT(CTRL_EN) |
115 | | WDT_BF(CTRL_PSEL, psel) |
116 | | WDT_BF(CTRL_KEY, 0xaa)); |
117 | spin_unlock(&wdt->io_lock); |
118 | } |
119 | |
120 | /* |
121 | * Pat the watchdog timer. |
122 | */ |
123 | static inline void at32_wdt_pat(void) |
124 | { |
125 | spin_lock(&wdt->io_lock); |
126 | wdt_writel(wdt, CLR, 0x42); |
127 | spin_unlock(&wdt->io_lock); |
128 | } |
129 | |
130 | /* |
131 | * Watchdog device is opened, and watchdog starts running. |
132 | */ |
133 | static int at32_wdt_open(struct inode *inode, struct file *file) |
134 | { |
135 | if (test_and_set_bit(1, &wdt->users)) |
136 | return -EBUSY; |
137 | |
138 | at32_wdt_start(); |
139 | return nonseekable_open(inode, file); |
140 | } |
141 | |
142 | /* |
143 | * Close the watchdog device. |
144 | */ |
145 | static int at32_wdt_close(struct inode *inode, struct file *file) |
146 | { |
147 | if (expect_release == 42) { |
148 | at32_wdt_stop(); |
149 | } else { |
150 | dev_dbg(wdt->miscdev.parent, |
151 | "unexpected close, not stopping watchdog!\n"); |
152 | at32_wdt_pat(); |
153 | } |
154 | clear_bit(1, &wdt->users); |
155 | expect_release = 0; |
156 | return 0; |
157 | } |
158 | |
159 | /* |
160 | * Change the watchdog time interval. |
161 | */ |
162 | static int at32_wdt_settimeout(int time) |
163 | { |
164 | /* |
165 | * All counting occurs at 1 / SLOW_CLOCK (32 kHz) and max prescaler is |
166 | * 2 ^ 16 allowing up to 2 seconds timeout. |
167 | */ |
168 | if ((time < TIMEOUT_MIN) || (time > TIMEOUT_MAX)) |
169 | return -EINVAL; |
170 | |
171 | /* |
172 | * Set new watchdog time. It will be used when at32_wdt_start() is |
173 | * called. |
174 | */ |
175 | wdt->timeout = time; |
176 | return 0; |
177 | } |
178 | |
179 | /* |
180 | * Get the watchdog status. |
181 | */ |
182 | static int at32_wdt_get_status(void) |
183 | { |
184 | int rcause; |
185 | int status = 0; |
186 | |
187 | rcause = wdt_readl(wdt, RCAUSE); |
188 | |
189 | switch (rcause) { |
190 | case WDT_BIT(RCAUSE_EXT): |
191 | status = WDIOF_EXTERN1; |
192 | break; |
193 | case WDT_BIT(RCAUSE_WDT): |
194 | status = WDIOF_CARDRESET; |
195 | break; |
196 | case WDT_BIT(RCAUSE_POR): /* fall through */ |
197 | case WDT_BIT(RCAUSE_JTAG): /* fall through */ |
198 | case WDT_BIT(RCAUSE_SERP): /* fall through */ |
199 | default: |
200 | break; |
201 | } |
202 | |
203 | return status; |
204 | } |
205 | |
206 | static const struct watchdog_info at32_wdt_info = { |
207 | .identity = "at32ap700x watchdog", |
208 | .options = WDIOF_SETTIMEOUT | |
209 | WDIOF_KEEPALIVEPING | |
210 | WDIOF_MAGICCLOSE, |
211 | }; |
212 | |
213 | /* |
214 | * Handle commands from user-space. |
215 | */ |
216 | static long at32_wdt_ioctl(struct file *file, |
217 | unsigned int cmd, unsigned long arg) |
218 | { |
219 | int ret = -ENOTTY; |
220 | int time; |
221 | void __user *argp = (void __user *)arg; |
222 | int __user *p = argp; |
223 | |
224 | switch (cmd) { |
225 | case WDIOC_GETSUPPORT: |
226 | ret = copy_to_user(argp, &at32_wdt_info, |
227 | sizeof(at32_wdt_info)) ? -EFAULT : 0; |
228 | break; |
229 | case WDIOC_GETSTATUS: |
230 | ret = put_user(0, p); |
231 | break; |
232 | case WDIOC_GETBOOTSTATUS: |
233 | ret = put_user(wdt->boot_status, p); |
234 | break; |
235 | case WDIOC_SETOPTIONS: |
236 | ret = get_user(time, p); |
237 | if (ret) |
238 | break; |
239 | if (time & WDIOS_DISABLECARD) |
240 | at32_wdt_stop(); |
241 | if (time & WDIOS_ENABLECARD) |
242 | at32_wdt_start(); |
243 | ret = 0; |
244 | break; |
245 | case WDIOC_KEEPALIVE: |
246 | at32_wdt_pat(); |
247 | ret = 0; |
248 | break; |
249 | case WDIOC_SETTIMEOUT: |
250 | ret = get_user(time, p); |
251 | if (ret) |
252 | break; |
253 | ret = at32_wdt_settimeout(time); |
254 | if (ret) |
255 | break; |
256 | /* Enable new time value */ |
257 | at32_wdt_start(); |
258 | /* fall through */ |
259 | case WDIOC_GETTIMEOUT: |
260 | ret = put_user(wdt->timeout, p); |
261 | break; |
262 | } |
263 | |
264 | return ret; |
265 | } |
266 | |
267 | static ssize_t at32_wdt_write(struct file *file, const char __user *data, |
268 | size_t len, loff_t *ppos) |
269 | { |
270 | /* See if we got the magic character 'V' and reload the timer */ |
271 | if (len) { |
272 | if (!nowayout) { |
273 | size_t i; |
274 | |
275 | /* |
276 | * note: just in case someone wrote the magic |
277 | * character five months ago... |
278 | */ |
279 | expect_release = 0; |
280 | |
281 | /* |
282 | * scan to see whether or not we got the magic |
283 | * character |
284 | */ |
285 | for (i = 0; i != len; i++) { |
286 | char c; |
287 | if (get_user(c, data + i)) |
288 | return -EFAULT; |
289 | if (c == 'V') |
290 | expect_release = 42; |
291 | } |
292 | } |
293 | /* someone wrote to us, we should pat the watchdog */ |
294 | at32_wdt_pat(); |
295 | } |
296 | return len; |
297 | } |
298 | |
299 | static const struct file_operations at32_wdt_fops = { |
300 | .owner = THIS_MODULE, |
301 | .llseek = no_llseek, |
302 | .unlocked_ioctl = at32_wdt_ioctl, |
303 | .open = at32_wdt_open, |
304 | .release = at32_wdt_close, |
305 | .write = at32_wdt_write, |
306 | }; |
307 | |
308 | static int __init at32_wdt_probe(struct platform_device *pdev) |
309 | { |
310 | struct resource *regs; |
311 | int ret; |
312 | |
313 | if (wdt) { |
314 | dev_dbg(&pdev->dev, "only 1 wdt instance supported.\n"); |
315 | return -EBUSY; |
316 | } |
317 | |
318 | regs = platform_get_resource(pdev, IORESOURCE_MEM, 0); |
319 | if (!regs) { |
320 | dev_dbg(&pdev->dev, "missing mmio resource\n"); |
321 | return -ENXIO; |
322 | } |
323 | |
324 | wdt = kzalloc(sizeof(struct wdt_at32ap700x), GFP_KERNEL); |
325 | if (!wdt) { |
326 | dev_dbg(&pdev->dev, "no memory for wdt structure\n"); |
327 | return -ENOMEM; |
328 | } |
329 | |
330 | wdt->regs = ioremap(regs->start, resource_size(regs)); |
331 | if (!wdt->regs) { |
332 | ret = -ENOMEM; |
333 | dev_dbg(&pdev->dev, "could not map I/O memory\n"); |
334 | goto err_free; |
335 | } |
336 | |
337 | spin_lock_init(&wdt->io_lock); |
338 | wdt->boot_status = at32_wdt_get_status(); |
339 | |
340 | /* Work-around for watchdog silicon errata. */ |
341 | if (wdt->boot_status & WDIOF_CARDRESET) { |
342 | dev_info(&pdev->dev, "CPU must be reset with external " |
343 | "reset or POR due to silicon errata.\n"); |
344 | ret = -EIO; |
345 | goto err_iounmap; |
346 | } else { |
347 | wdt->users = 0; |
348 | } |
349 | |
350 | wdt->miscdev.minor = WATCHDOG_MINOR; |
351 | wdt->miscdev.name = "watchdog"; |
352 | wdt->miscdev.fops = &at32_wdt_fops; |
353 | wdt->miscdev.parent = &pdev->dev; |
354 | |
355 | platform_set_drvdata(pdev, wdt); |
356 | |
357 | if (at32_wdt_settimeout(timeout)) { |
358 | at32_wdt_settimeout(TIMEOUT_DEFAULT); |
359 | dev_dbg(&pdev->dev, |
360 | "default timeout invalid, set to %d sec.\n", |
361 | TIMEOUT_DEFAULT); |
362 | } |
363 | |
364 | ret = misc_register(&wdt->miscdev); |
365 | if (ret) { |
366 | dev_dbg(&pdev->dev, "failed to register wdt miscdev\n"); |
367 | goto err_register; |
368 | } |
369 | |
370 | dev_info(&pdev->dev, |
371 | "AT32AP700X WDT at 0x%p, timeout %d sec (nowayout=%d)\n", |
372 | wdt->regs, wdt->timeout, nowayout); |
373 | |
374 | return 0; |
375 | |
376 | err_register: |
377 | platform_set_drvdata(pdev, NULL); |
378 | err_iounmap: |
379 | iounmap(wdt->regs); |
380 | err_free: |
381 | kfree(wdt); |
382 | wdt = NULL; |
383 | return ret; |
384 | } |
385 | |
386 | static int __exit at32_wdt_remove(struct platform_device *pdev) |
387 | { |
388 | if (wdt && platform_get_drvdata(pdev) == wdt) { |
389 | /* Stop the timer before we leave */ |
390 | if (!nowayout) |
391 | at32_wdt_stop(); |
392 | |
393 | misc_deregister(&wdt->miscdev); |
394 | iounmap(wdt->regs); |
395 | kfree(wdt); |
396 | wdt = NULL; |
397 | platform_set_drvdata(pdev, NULL); |
398 | } |
399 | return 0; |
400 | } |
401 | |
402 | static void at32_wdt_shutdown(struct platform_device *pdev) |
403 | { |
404 | at32_wdt_stop(); |
405 | } |
406 | |
407 | #ifdef CONFIG_PM |
408 | static int at32_wdt_suspend(struct platform_device *pdev, pm_message_t message) |
409 | { |
410 | at32_wdt_stop(); |
411 | return 0; |
412 | } |
413 | |
414 | static int at32_wdt_resume(struct platform_device *pdev) |
415 | { |
416 | if (wdt->users) |
417 | at32_wdt_start(); |
418 | return 0; |
419 | } |
420 | #else |
421 | #define at32_wdt_suspend NULL |
422 | #define at32_wdt_resume NULL |
423 | #endif |
424 | |
425 | /* work with hotplug and coldplug */ |
426 | MODULE_ALIAS("platform:at32_wdt"); |
427 | |
428 | static struct platform_driver at32_wdt_driver = { |
429 | .remove = __exit_p(at32_wdt_remove), |
430 | .suspend = at32_wdt_suspend, |
431 | .resume = at32_wdt_resume, |
432 | .driver = { |
433 | .name = "at32_wdt", |
434 | .owner = THIS_MODULE, |
435 | }, |
436 | .shutdown = at32_wdt_shutdown, |
437 | }; |
438 | |
439 | module_platform_driver_probe(at32_wdt_driver, at32_wdt_probe); |
440 | |
441 | MODULE_AUTHOR("Hans-Christian Egtvedt <egtvedt@samfundet.no>"); |
442 | MODULE_DESCRIPTION("Watchdog driver for Atmel AT32AP700X"); |
443 | MODULE_LICENSE("GPL"); |
444 | MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR); |
445 |
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