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Hans-Christian Egtvedta9cb3952007-06-07 16:06:41 -07001/*
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.
Hans-Christian Egtvedtbb133452007-10-30 14:56:20 +01009 *
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.
Hans-Christian Egtvedta9cb3952007-06-07 16:06:41 -070022 */
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>
Andrew Mortonc37f2712007-06-07 16:06:43 -070032#include <linux/uaccess.h>
33#include <linux/io.h>
Wim Van Sebroecke75e6572007-07-03 17:59:04 +000034#include <linux/spinlock.h>
Hans-Christian Egtvedta9cb3952007-06-07 16:06:41 -070035
36#define TIMEOUT_MIN 1
Hans-Christian Egtvedta9cb3952007-06-07 16:06:41 -070037#define TIMEOUT_MAX 2
Wim Van Sebroeck726c9f62007-06-18 22:49:35 +020038#define TIMEOUT_DEFAULT TIMEOUT_MAX
39
40/* module parameters */
41static int timeout = TIMEOUT_DEFAULT;
42module_param(timeout, int, 0);
43MODULE_PARM_DESC(timeout,
44 "Timeout value. Limited to be 1 or 2 seconds. (default="
45 __MODULE_STRING(TIMEOUT_DEFAULT) ")");
Hans-Christian Egtvedta9cb3952007-06-07 16:06:41 -070046
Wim Van Sebroeck28401142007-06-20 23:36:43 +020047static int nowayout = WATCHDOG_NOWAYOUT;
48module_param(nowayout, int, 0);
49MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
50 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
51
Hans-Christian Egtvedta9cb3952007-06-07 16:06:41 -070052/* 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
Hans-Christian Egtvedtbb133452007-10-30 14:56:20 +010060#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
Hans-Christian Egtvedta9cb3952007-06-07 16:06:41 -070067#define WDT_BIT(name) (1 << WDT_##name)
Wim Van Sebroeckc0ead7e2007-06-17 19:34:23 +000068#define WDT_BF(name, value) ((value) << WDT_##name)
Hans-Christian Egtvedta9cb3952007-06-07 16:06:41 -070069
Wim Van Sebroeckc0ead7e2007-06-17 19:34:23 +000070#define wdt_readl(dev, reg) \
Hans-Christian Egtvedta9cb3952007-06-07 16:06:41 -070071 __raw_readl((dev)->regs + WDT_##reg)
Wim Van Sebroeckc0ead7e2007-06-17 19:34:23 +000072#define wdt_writel(dev, reg, value) \
Hans-Christian Egtvedta9cb3952007-06-07 16:06:41 -070073 __raw_writel((value), (dev)->regs + WDT_##reg)
74
75struct wdt_at32ap700x {
76 void __iomem *regs;
Wim Van Sebroecke75e6572007-07-03 17:59:04 +000077 spinlock_t io_lock;
Hans-Christian Egtvedta9cb3952007-06-07 16:06:41 -070078 int timeout;
Hans-Christian Egtvedtbb133452007-10-30 14:56:20 +010079 int boot_status;
Wim Van Sebroeck7e2a1492007-07-03 17:59:29 +000080 unsigned long users;
Hans-Christian Egtvedta9cb3952007-06-07 16:06:41 -070081 struct miscdevice miscdev;
82};
83
84static struct wdt_at32ap700x *wdt;
Wim Van Sebroeck28401142007-06-20 23:36:43 +020085static char expect_release;
Hans-Christian Egtvedta9cb3952007-06-07 16:06:41 -070086
87/*
88 * Disable the watchdog.
89 */
Wim Van Sebroeckc0ead7e2007-06-17 19:34:23 +000090static inline void at32_wdt_stop(void)
Hans-Christian Egtvedta9cb3952007-06-07 16:06:41 -070091{
Wim Van Sebroeck7e2a1492007-07-03 17:59:29 +000092 unsigned long psel;
93
Wim Van Sebroecke75e6572007-07-03 17:59:04 +000094 spin_lock(&wdt->io_lock);
Wim Van Sebroeck7e2a1492007-07-03 17:59:29 +000095 psel = wdt_readl(wdt, CTRL) & WDT_BF(CTRL_PSEL, 0x0f);
Hans-Christian Egtvedta9cb3952007-06-07 16:06:41 -070096 wdt_writel(wdt, CTRL, psel | WDT_BF(CTRL_KEY, 0x55));
97 wdt_writel(wdt, CTRL, psel | WDT_BF(CTRL_KEY, 0xaa));
Wim Van Sebroecke75e6572007-07-03 17:59:04 +000098 spin_unlock(&wdt->io_lock);
Hans-Christian Egtvedta9cb3952007-06-07 16:06:41 -070099}
100
101/*
102 * Enable and reset the watchdog.
103 */
Wim Van Sebroeckc0ead7e2007-06-17 19:34:23 +0000104static inline void at32_wdt_start(void)
Hans-Christian Egtvedta9cb3952007-06-07 16:06:41 -0700105{
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
Wim Van Sebroecke75e6572007-07-03 17:59:04 +0000109 spin_lock(&wdt->io_lock);
Hans-Christian Egtvedta9cb3952007-06-07 16:06:41 -0700110 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));
Wim Van Sebroecke75e6572007-07-03 17:59:04 +0000116 spin_unlock(&wdt->io_lock);
Hans-Christian Egtvedta9cb3952007-06-07 16:06:41 -0700117}
118
119/*
120 * Pat the watchdog timer.
121 */
Wim Van Sebroeckc0ead7e2007-06-17 19:34:23 +0000122static inline void at32_wdt_pat(void)
Hans-Christian Egtvedta9cb3952007-06-07 16:06:41 -0700123{
Wim Van Sebroecke75e6572007-07-03 17:59:04 +0000124 spin_lock(&wdt->io_lock);
Hans-Christian Egtvedta9cb3952007-06-07 16:06:41 -0700125 wdt_writel(wdt, CLR, 0x42);
Wim Van Sebroecke75e6572007-07-03 17:59:04 +0000126 spin_unlock(&wdt->io_lock);
Hans-Christian Egtvedta9cb3952007-06-07 16:06:41 -0700127}
128
129/*
130 * Watchdog device is opened, and watchdog starts running.
131 */
132static 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/*
Wim Van Sebroeck28401142007-06-20 23:36:43 +0200142 * Close the watchdog device.
Hans-Christian Egtvedta9cb3952007-06-07 16:06:41 -0700143 */
144static int at32_wdt_close(struct inode *inode, struct file *file)
145{
Wim Van Sebroeck28401142007-06-20 23:36:43 +0200146 if (expect_release == 42) {
147 at32_wdt_stop();
148 } else {
149 dev_dbg(wdt->miscdev.parent,
Hans-Christian Egtvedtbb133452007-10-30 14:56:20 +0100150 "unexpected close, not stopping watchdog!\n");
Wim Van Sebroeck28401142007-06-20 23:36:43 +0200151 at32_wdt_pat();
152 }
Hans-Christian Egtvedta9cb3952007-06-07 16:06:41 -0700153 clear_bit(1, &wdt->users);
Wim Van Sebroeck28401142007-06-20 23:36:43 +0200154 expect_release = 0;
Hans-Christian Egtvedta9cb3952007-06-07 16:06:41 -0700155 return 0;
156}
157
158/*
159 * Change the watchdog time interval.
160 */
161static 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
Andrew Mortonc37f2712007-06-07 16:06:43 -0700170 /*
171 * Set new watchdog time. It will be used when at32_wdt_start() is
172 * called.
173 */
Hans-Christian Egtvedta9cb3952007-06-07 16:06:41 -0700174 wdt->timeout = time;
175 return 0;
176}
177
Hans-Christian Egtvedtbb133452007-10-30 14:56:20 +0100178/*
179 * Get the watchdog status.
180 */
181static 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
Hans-Christian Egtvedta9cb3952007-06-07 16:06:41 -0700205static struct watchdog_info at32_wdt_info = {
206 .identity = "at32ap700x watchdog",
Wim Van Sebroeck28401142007-06-20 23:36:43 +0200207 .options = WDIOF_SETTIMEOUT |
208 WDIOF_KEEPALIVEPING |
209 WDIOF_MAGICCLOSE,
Hans-Christian Egtvedta9cb3952007-06-07 16:06:41 -0700210};
211
212/*
213 * Handle commands from user-space.
214 */
215static 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
Andrew Mortonc37f2712007-06-07 16:06:43 -0700223 switch (cmd) {
Hans-Christian Egtvedta9cb3952007-06-07 16:06:41 -0700224 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;
Hans-Christian Egtvedtbb133452007-10-30 14:56:20 +0100245 case WDIOC_GETSTATUS:
Hans-Christian Egtvedta9cb3952007-06-07 16:06:41 -0700246 ret = put_user(0, p);
247 break;
Hans-Christian Egtvedtbb133452007-10-30 14:56:20 +0100248 case WDIOC_GETBOOTSTATUS:
249 ret = put_user(wdt->boot_status, p);
250 break;
Hans-Christian Egtvedta9cb3952007-06-07 16:06:41 -0700251 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
Wim Van Sebroeck28401142007-06-20 23:36:43 +0200266static ssize_t at32_wdt_write(struct file *file, const char __user *data,
267 size_t len, loff_t *ppos)
Hans-Christian Egtvedta9cb3952007-06-07 16:06:41 -0700268{
Wim Van Sebroeck28401142007-06-20 23:36:43 +0200269 /* 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 }
Hans-Christian Egtvedta9cb3952007-06-07 16:06:41 -0700295 return len;
296}
297
298static 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
307static 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);
Hans-Christian Egtvedt47d17762007-06-08 11:03:01 -0700330 if (!wdt->regs) {
331 ret = -ENOMEM;
332 dev_dbg(&pdev->dev, "could not map I/O memory\n");
333 goto err_free;
334 }
Hans-Christian Egtvedtbb133452007-10-30 14:56:20 +0100335
Wim Van Sebroecke75e6572007-07-03 17:59:04 +0000336 spin_lock_init(&wdt->io_lock);
Hans-Christian Egtvedtbb133452007-10-30 14:56:20 +0100337 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 }
Hans-Christian Egtvedta9cb3952007-06-07 16:06:41 -0700348 wdt->miscdev.minor = WATCHDOG_MINOR;
349 wdt->miscdev.name = "watchdog";
350 wdt->miscdev.fops = &at32_wdt_fops;
351
Wim Van Sebroeck726c9f62007-06-18 22:49:35 +0200352 if (at32_wdt_settimeout(timeout)) {
353 at32_wdt_settimeout(TIMEOUT_DEFAULT);
Hans-Christian Egtvedta9cb3952007-06-07 16:06:41 -0700354 dev_dbg(&pdev->dev,
355 "default timeout invalid, set to %d sec.\n",
Wim Van Sebroeck726c9f62007-06-18 22:49:35 +0200356 TIMEOUT_DEFAULT);
Hans-Christian Egtvedta9cb3952007-06-07 16:06:41 -0700357 }
358
359 ret = misc_register(&wdt->miscdev);
360 if (ret) {
361 dev_dbg(&pdev->dev, "failed to register wdt miscdev\n");
Hans-Christian Egtvedt47d17762007-06-08 11:03:01 -0700362 goto err_iounmap;
Hans-Christian Egtvedta9cb3952007-06-07 16:06:41 -0700363 }
364
365 platform_set_drvdata(pdev, wdt);
366 wdt->miscdev.parent = &pdev->dev;
Wim Van Sebroeck28401142007-06-20 23:36:43 +0200367 dev_info(&pdev->dev,
368 "AT32AP700X WDT at 0x%p, timeout %d sec (nowayout=%d)\n",
369 wdt->regs, wdt->timeout, nowayout);
Hans-Christian Egtvedta9cb3952007-06-07 16:06:41 -0700370
371 return 0;
372
Hans-Christian Egtvedt47d17762007-06-08 11:03:01 -0700373err_iounmap:
374 iounmap(wdt->regs);
375err_free:
Hans-Christian Egtvedta9cb3952007-06-07 16:06:41 -0700376 kfree(wdt);
377 wdt = NULL;
378 return ret;
379}
380
381static int __exit at32_wdt_remove(struct platform_device *pdev)
382{
383 if (wdt && platform_get_drvdata(pdev) == wdt) {
Wim Van Sebroeck28401142007-06-20 23:36:43 +0200384 /* Stop the timer before we leave */
385 if (!nowayout)
386 at32_wdt_stop();
387
Hans-Christian Egtvedta9cb3952007-06-07 16:06:41 -0700388 misc_deregister(&wdt->miscdev);
Hans-Christian Egtvedtff732312007-06-08 11:01:47 -0700389 iounmap(wdt->regs);
Hans-Christian Egtvedta9cb3952007-06-07 16:06:41 -0700390 kfree(wdt);
391 wdt = NULL;
392 platform_set_drvdata(pdev, NULL);
393 }
394
395 return 0;
396}
397
398static void at32_wdt_shutdown(struct platform_device *pdev)
399{
400 at32_wdt_stop();
401}
402
403#ifdef CONFIG_PM
404static int at32_wdt_suspend(struct platform_device *pdev, pm_message_t message)
405{
406 at32_wdt_stop();
407 return 0;
408}
409
410static int at32_wdt_resume(struct platform_device *pdev)
411{
412 if (wdt->users)
413 at32_wdt_start();
414 return 0;
415}
Andrew Morton97a2a2e2007-06-07 16:08:53 -0700416#else
417#define at32_wdt_suspend NULL
418#define at32_wdt_resume NULL
Hans-Christian Egtvedta9cb3952007-06-07 16:06:41 -0700419#endif
420
421static struct platform_driver at32_wdt_driver = {
422 .remove = __exit_p(at32_wdt_remove),
Hans-Christian Egtvedta9cb3952007-06-07 16:06:41 -0700423 .suspend = at32_wdt_suspend,
424 .resume = at32_wdt_resume,
Hans-Christian Egtvedta9cb3952007-06-07 16:06:41 -0700425 .driver = {
426 .name = "at32_wdt",
427 .owner = THIS_MODULE,
428 },
429 .shutdown = at32_wdt_shutdown,
430};
431
432static int __init at32_wdt_init(void)
433{
434 return platform_driver_probe(&at32_wdt_driver, at32_wdt_probe);
435}
436module_init(at32_wdt_init);
437
438static void __exit at32_wdt_exit(void)
439{
440 platform_driver_unregister(&at32_wdt_driver);
441}
442module_exit(at32_wdt_exit);
443
444MODULE_AUTHOR("Hans-Christian Egtvedt <hcegtvedt@atmel.com>");
445MODULE_DESCRIPTION("Watchdog driver for Atmel AT32AP700X");
446MODULE_LICENSE("GPL");
447MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);