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
36 #define TIMEOUT_MIN 1
37 #define TIMEOUT_MAX 2
38 #define TIMEOUT_DEFAULT TIMEOUT_MAX
39
40 /* module parameters */
41 static int timeout = TIMEOUT_DEFAULT;
42 module_param(timeout, int, 0);
43 MODULE_PARM_DESC(timeout,
44 "Timeout value. Limited to be 1 or 2 seconds. (default="
45 __MODULE_STRING(TIMEOUT_DEFAULT) ")");
46
47 static int nowayout = WATCHDOG_NOWAYOUT;
48 module_param(nowayout, int, 0);
49 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
50 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
51
52 /* Watchdog registers and write/read macro */
53 #define WDT_CTRL 0x00
54 #define WDT_CTRL_EN 0
55 #define WDT_CTRL_PSEL 8
56 #define WDT_CTRL_KEY 24
57
58 #define WDT_CLR 0x04
59
60 #define WDT_RCAUSE 0x10
61 #define WDT_RCAUSE_POR 0
62 #define WDT_RCAUSE_EXT 2
63 #define WDT_RCAUSE_WDT 3
64 #define WDT_RCAUSE_JTAG 4
65 #define WDT_RCAUSE_SERP 5
66
67 #define WDT_BIT(name) (1 << WDT_##name)
68 #define WDT_BF(name, value) ((value) << WDT_##name)
69
70 #define wdt_readl(dev, reg) \
71 __raw_readl((dev)->regs + WDT_##reg)
72 #define wdt_writel(dev, reg, value) \
73 __raw_writel((value), (dev)->regs + WDT_##reg)
74
75 struct wdt_at32ap700x {
76 void __iomem *regs;
77 spinlock_t io_lock;
78 int timeout;
79 int boot_status;
80 unsigned long users;
81 struct miscdevice miscdev;
82 };
83
84 static struct wdt_at32ap700x *wdt;
85 static char expect_release;
86
87 /*
88 * Disable the watchdog.
89 */
90 static inline void at32_wdt_stop(void)
91 {
92 unsigned long psel;
93
94 spin_lock(&wdt->io_lock);
95 psel = wdt_readl(wdt, CTRL) & WDT_BF(CTRL_PSEL, 0x0f);
96 wdt_writel(wdt, CTRL, psel | WDT_BF(CTRL_KEY, 0x55));
97 wdt_writel(wdt, CTRL, psel | WDT_BF(CTRL_KEY, 0xaa));
98 spin_unlock(&wdt->io_lock);
99 }
100
101 /*
102 * Enable and reset the watchdog.
103 */
104 static inline void at32_wdt_start(void)
105 {
106 /* 0xf is 2^16 divider = 2 sec, 0xe is 2^15 divider = 1 sec */
107 unsigned long psel = (wdt->timeout > 1) ? 0xf : 0xe;
108
109 spin_lock(&wdt->io_lock);
110 wdt_writel(wdt, CTRL, WDT_BIT(CTRL_EN)
111 | WDT_BF(CTRL_PSEL, psel)
112 | WDT_BF(CTRL_KEY, 0x55));
113 wdt_writel(wdt, CTRL, WDT_BIT(CTRL_EN)
114 | WDT_BF(CTRL_PSEL, psel)
115 | WDT_BF(CTRL_KEY, 0xaa));
116 spin_unlock(&wdt->io_lock);
117 }
118
119 /*
120 * Pat the watchdog timer.
121 */
122 static inline void at32_wdt_pat(void)
123 {
124 spin_lock(&wdt->io_lock);
125 wdt_writel(wdt, CLR, 0x42);
126 spin_unlock(&wdt->io_lock);
127 }
128
129 /*
130 * Watchdog device is opened, and watchdog starts running.
131 */
132 static int at32_wdt_open(struct inode *inode, struct file *file)
133 {
134 if (test_and_set_bit(1, &wdt->users))
135 return -EBUSY;
136
137 at32_wdt_start();
138 return nonseekable_open(inode, file);
139 }
140
141 /*
142 * Close the watchdog device.
143 */
144 static int at32_wdt_close(struct inode *inode, struct file *file)
145 {
146 if (expect_release == 42) {
147 at32_wdt_stop();
148 } else {
149 dev_dbg(wdt->miscdev.parent,
150 "unexpected close, not stopping watchdog!\n");
151 at32_wdt_pat();
152 }
153 clear_bit(1, &wdt->users);
154 expect_release = 0;
155 return 0;
156 }
157
158 /*
159 * Change the watchdog time interval.
160 */
161 static int at32_wdt_settimeout(int time)
162 {
163 /*
164 * All counting occurs at 1 / SLOW_CLOCK (32 kHz) and max prescaler is
165 * 2 ^ 16 allowing up to 2 seconds timeout.
166 */
167 if ((time < TIMEOUT_MIN) || (time > TIMEOUT_MAX))
168 return -EINVAL;
169
170 /*
171 * Set new watchdog time. It will be used when at32_wdt_start() is
172 * called.
173 */
174 wdt->timeout = time;
175 return 0;
176 }
177
178 /*
179 * Get the watchdog status.
180 */
181 static int at32_wdt_get_status(void)
182 {
183 int rcause;
184 int status = 0;
185
186 rcause = wdt_readl(wdt, RCAUSE);
187
188 switch (rcause) {
189 case WDT_BIT(RCAUSE_EXT):
190 status = WDIOF_EXTERN1;
191 break;
192 case WDT_BIT(RCAUSE_WDT):
193 status = WDIOF_CARDRESET;
194 break;
195 case WDT_BIT(RCAUSE_POR): /* fall through */
196 case WDT_BIT(RCAUSE_JTAG): /* fall through */
197 case WDT_BIT(RCAUSE_SERP): /* fall through */
198 default:
199 break;
200 }
201
202 return status;
203 }
204
205 static struct watchdog_info at32_wdt_info = {
206 .identity = "at32ap700x watchdog",
207 .options = WDIOF_SETTIMEOUT |
208 WDIOF_KEEPALIVEPING |
209 WDIOF_MAGICCLOSE,
210 };
211
212 /*
213 * Handle commands from user-space.
214 */
215 static int at32_wdt_ioctl(struct inode *inode, struct file *file,
216 unsigned int cmd, unsigned long arg)
217 {
218 int ret = -ENOTTY;
219 int time;
220 void __user *argp = (void __user *)arg;
221 int __user *p = argp;
222
223 switch (cmd) {
224 case WDIOC_KEEPALIVE:
225 at32_wdt_pat();
226 ret = 0;
227 break;
228 case WDIOC_GETSUPPORT:
229 ret = copy_to_user(argp, &at32_wdt_info,
230 sizeof(at32_wdt_info)) ? -EFAULT : 0;
231 break;
232 case WDIOC_SETTIMEOUT:
233 ret = get_user(time, p);
234 if (ret)
235 break;
236 ret = at32_wdt_settimeout(time);
237 if (ret)
238 break;
239 /* Enable new time value */
240 at32_wdt_start();
241 /* fall through */
242 case WDIOC_GETTIMEOUT:
243 ret = put_user(wdt->timeout, p);
244 break;
245 case WDIOC_GETSTATUS:
246 ret = put_user(0, p);
247 break;
248 case WDIOC_GETBOOTSTATUS:
249 ret = put_user(wdt->boot_status, p);
250 break;
251 case WDIOC_SETOPTIONS:
252 ret = get_user(time, p);
253 if (ret)
254 break;
255 if (time & WDIOS_DISABLECARD)
256 at32_wdt_stop();
257 if (time & WDIOS_ENABLECARD)
258 at32_wdt_start();
259 ret = 0;
260 break;
261 }
262
263 return ret;
264 }
265
266 static ssize_t at32_wdt_write(struct file *file, const char __user *data,
267 size_t len, loff_t *ppos)
268 {
269 /* See if we got the magic character 'V' and reload the timer */
270 if (len) {
271 if (!nowayout) {
272 size_t i;
273
274 /*
275 * note: just in case someone wrote the magic
276 * character five months ago...
277 */
278 expect_release = 0;
279
280 /*
281 * scan to see whether or not we got the magic
282 * character
283 */
284 for (i = 0; i != len; i++) {
285 char c;
286 if (get_user(c, data+i))
287 return -EFAULT;
288 if (c == 'V')
289 expect_release = 42;
290 }
291 }
292 /* someone wrote to us, we should pat the watchdog */
293 at32_wdt_pat();
294 }
295 return len;
296 }
297
298 static const struct file_operations at32_wdt_fops = {
299 .owner = THIS_MODULE,
300 .llseek = no_llseek,
301 .ioctl = at32_wdt_ioctl,
302 .open = at32_wdt_open,
303 .release = at32_wdt_close,
304 .write = at32_wdt_write,
305 };
306
307 static int __init at32_wdt_probe(struct platform_device *pdev)
308 {
309 struct resource *regs;
310 int ret;
311
312 if (wdt) {
313 dev_dbg(&pdev->dev, "only 1 wdt instance supported.\n");
314 return -EBUSY;
315 }
316
317 regs = platform_get_resource(pdev, IORESOURCE_MEM, 0);
318 if (!regs) {
319 dev_dbg(&pdev->dev, "missing mmio resource\n");
320 return -ENXIO;
321 }
322
323 wdt = kzalloc(sizeof(struct wdt_at32ap700x), GFP_KERNEL);
324 if (!wdt) {
325 dev_dbg(&pdev->dev, "no memory for wdt structure\n");
326 return -ENOMEM;
327 }
328
329 wdt->regs = ioremap(regs->start, regs->end - regs->start + 1);
330 if (!wdt->regs) {
331 ret = -ENOMEM;
332 dev_dbg(&pdev->dev, "could not map I/O memory\n");
333 goto err_free;
334 }
335
336 spin_lock_init(&wdt->io_lock);
337 wdt->boot_status = at32_wdt_get_status();
338
339 /* Work-around for watchdog silicon errata. */
340 if (wdt->boot_status & WDIOF_CARDRESET) {
341 dev_info(&pdev->dev, "CPU must be reset with external "
342 "reset or POR due to silicon errata.\n");
343 ret = -EIO;
344 goto err_iounmap;
345 } else {
346 wdt->users = 0;
347 }
348 wdt->miscdev.minor = WATCHDOG_MINOR;
349 wdt->miscdev.name = "watchdog";
350 wdt->miscdev.fops = &at32_wdt_fops;
351
352 if (at32_wdt_settimeout(timeout)) {
353 at32_wdt_settimeout(TIMEOUT_DEFAULT);
354 dev_dbg(&pdev->dev,
355 "default timeout invalid, set to %d sec.\n",
356 TIMEOUT_DEFAULT);
357 }
358
359 ret = misc_register(&wdt->miscdev);
360 if (ret) {
361 dev_dbg(&pdev->dev, "failed to register wdt miscdev\n");
362 goto err_iounmap;
363 }
364
365 platform_set_drvdata(pdev, wdt);
366 wdt->miscdev.parent = &pdev->dev;
367 dev_info(&pdev->dev,
368 "AT32AP700X WDT at 0x%p, timeout %d sec (nowayout=%d)\n",
369 wdt->regs, wdt->timeout, nowayout);
370
371 return 0;
372
373 err_iounmap:
374 iounmap(wdt->regs);
375 err_free:
376 kfree(wdt);
377 wdt = NULL;
378 return ret;
379 }
380
381 static int __exit at32_wdt_remove(struct platform_device *pdev)
382 {
383 if (wdt && platform_get_drvdata(pdev) == wdt) {
384 /* Stop the timer before we leave */
385 if (!nowayout)
386 at32_wdt_stop();
387
388 misc_deregister(&wdt->miscdev);
389 iounmap(wdt->regs);
390 kfree(wdt);
391 wdt = NULL;
392 platform_set_drvdata(pdev, NULL);
393 }
394
395 return 0;
396 }
397
398 static void at32_wdt_shutdown(struct platform_device *pdev)
399 {
400 at32_wdt_stop();
401 }
402
403 #ifdef CONFIG_PM
404 static int at32_wdt_suspend(struct platform_device *pdev, pm_message_t message)
405 {
406 at32_wdt_stop();
407 return 0;
408 }
409
410 static int at32_wdt_resume(struct platform_device *pdev)
411 {
412 if (wdt->users)
413 at32_wdt_start();
414 return 0;
415 }
416 #else
417 #define at32_wdt_suspend NULL
418 #define at32_wdt_resume NULL
419 #endif
420
421 /* work with hotplug and coldplug */
422 MODULE_ALIAS("platform:at32_wdt");
423
424 static struct platform_driver at32_wdt_driver = {
425 .remove = __exit_p(at32_wdt_remove),
426 .suspend = at32_wdt_suspend,
427 .resume = at32_wdt_resume,
428 .driver = {
429 .name = "at32_wdt",
430 .owner = THIS_MODULE,
431 },
432 .shutdown = at32_wdt_shutdown,
433 };
434
435 static int __init at32_wdt_init(void)
436 {
437 return platform_driver_probe(&at32_wdt_driver, at32_wdt_probe);
438 }
439 module_init(at32_wdt_init);
440
441 static void __exit at32_wdt_exit(void)
442 {
443 platform_driver_unregister(&at32_wdt_driver);
444 }
445 module_exit(at32_wdt_exit);
446
447 MODULE_AUTHOR("Hans-Christian Egtvedt <hcegtvedt@atmel.com>");
448 MODULE_DESCRIPTION("Watchdog driver for Atmel AT32AP700X");
449 MODULE_LICENSE("GPL");
450 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
451
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