2 * Watchdog driver for Atmel AT32AP700X devices
4 * Copyright (C) 2005-2006 Atmel Corporation
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.
11 * Errata: WDT Clear is blocked after WDT Reset
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.
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.
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>
30 #include <linux/platform_device.h>
31 #include <linux/watchdog.h>
32 #include <linux/uaccess.h>
34 #include <linux/spinlock.h>
38 #define TIMEOUT_DEFAULT TIMEOUT_MAX
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) ")");
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) ")");
52 /* Watchdog registers and write/read macro */
55 #define WDT_CTRL_PSEL 8
56 #define WDT_CTRL_KEY 24
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
67 #define WDT_BIT(name) (1 << WDT_##name)
68 #define WDT_BF(name, value) ((value) << WDT_##name)
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)
75 struct wdt_at32ap700x {
81 struct miscdevice miscdev;
84 static struct wdt_at32ap700x *wdt;
85 static char expect_release;
88 * Disable the watchdog.
90 static inline void at32_wdt_stop(void)
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);
102 * Enable and reset the watchdog.
104 static inline void at32_wdt_start(void)
106 /* 0xf is 2^16 divider = 2 sec, 0xe is 2^15 divider = 1 sec */
107 unsigned long psel = (wdt->timeout > 1) ? 0xf : 0xe;
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);
120 * Pat the watchdog timer.
122 static inline void at32_wdt_pat(void)
124 spin_lock(&wdt->io_lock);
125 wdt_writel(wdt, CLR, 0x42);
126 spin_unlock(&wdt->io_lock);
130 * Watchdog device is opened, and watchdog starts running.
132 static int at32_wdt_open(struct inode *inode, struct file *file)
134 if (test_and_set_bit(1, &wdt->users))
138 return nonseekable_open(inode, file);
142 * Close the watchdog device.
144 static int at32_wdt_close(struct inode *inode, struct file *file)
146 if (expect_release == 42) {
149 dev_dbg(wdt->miscdev.parent,
150 "unexpected close, not stopping watchdog!\n");
153 clear_bit(1, &wdt->users);
159 * Change the watchdog time interval.
161 static int at32_wdt_settimeout(int time)
164 * All counting occurs at 1 / SLOW_CLOCK (32 kHz) and max prescaler is
165 * 2 ^ 16 allowing up to 2 seconds timeout.
167 if ((time < TIMEOUT_MIN) || (time > TIMEOUT_MAX))
171 * Set new watchdog time. It will be used when at32_wdt_start() is
179 * Get the watchdog status.
181 static int at32_wdt_get_status(void)
186 rcause = wdt_readl(wdt, RCAUSE);
189 case WDT_BIT(RCAUSE_EXT):
190 status = WDIOF_EXTERN1;
192 case WDT_BIT(RCAUSE_WDT):
193 status = WDIOF_CARDRESET;
195 case WDT_BIT(RCAUSE_POR): /* fall through */
196 case WDT_BIT(RCAUSE_JTAG): /* fall through */
197 case WDT_BIT(RCAUSE_SERP): /* fall through */
205 static struct watchdog_info at32_wdt_info = {
206 .identity = "at32ap700x watchdog",
207 .options = WDIOF_SETTIMEOUT |
208 WDIOF_KEEPALIVEPING |
213 * Handle commands from user-space.
215 static long at32_wdt_ioctl(struct file *file,
216 unsigned int cmd, unsigned long arg)
220 void __user *argp = (void __user *)arg;
221 int __user *p = argp;
224 case WDIOC_GETSUPPORT:
225 ret = copy_to_user(argp, &at32_wdt_info,
226 sizeof(at32_wdt_info)) ? -EFAULT : 0;
228 case WDIOC_GETSTATUS:
229 ret = put_user(0, p);
231 case WDIOC_GETBOOTSTATUS:
232 ret = put_user(wdt->boot_status, p);
234 case WDIOC_SETOPTIONS:
235 ret = get_user(time, p);
238 if (time & WDIOS_DISABLECARD)
240 if (time & WDIOS_ENABLECARD)
244 case WDIOC_KEEPALIVE:
248 case WDIOC_SETTIMEOUT:
249 ret = get_user(time, p);
252 ret = at32_wdt_settimeout(time);
255 /* Enable new time value */
258 case WDIOC_GETTIMEOUT:
259 ret = put_user(wdt->timeout, p);
266 static ssize_t at32_wdt_write(struct file *file, const char __user *data,
267 size_t len, loff_t *ppos)
269 /* See if we got the magic character 'V' and reload the timer */
275 * note: just in case someone wrote the magic
276 * character five months ago...
281 * scan to see whether or not we got the magic
284 for (i = 0; i != len; i++) {
286 if (get_user(c, data + i))
292 /* someone wrote to us, we should pat the watchdog */
298 static const struct file_operations at32_wdt_fops = {
299 .owner = THIS_MODULE,
301 .unlocked_ioctl = at32_wdt_ioctl,
302 .open = at32_wdt_open,
303 .release = at32_wdt_close,
304 .write = at32_wdt_write,
307 static int __init at32_wdt_probe(struct platform_device *pdev)
309 struct resource *regs;
313 dev_dbg(&pdev->dev, "only 1 wdt instance supported.\n");
317 regs = platform_get_resource(pdev, IORESOURCE_MEM, 0);
319 dev_dbg(&pdev->dev, "missing mmio resource\n");
323 wdt = kzalloc(sizeof(struct wdt_at32ap700x), GFP_KERNEL);
325 dev_dbg(&pdev->dev, "no memory for wdt structure\n");
329 wdt->regs = ioremap(regs->start, regs->end - regs->start + 1);
332 dev_dbg(&pdev->dev, "could not map I/O memory\n");
336 spin_lock_init(&wdt->io_lock);
337 wdt->boot_status = at32_wdt_get_status();
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");
348 wdt->miscdev.minor = WATCHDOG_MINOR;
349 wdt->miscdev.name = "watchdog";
350 wdt->miscdev.fops = &at32_wdt_fops;
352 if (at32_wdt_settimeout(timeout)) {
353 at32_wdt_settimeout(TIMEOUT_DEFAULT);
355 "default timeout invalid, set to %d sec.\n",
359 ret = misc_register(&wdt->miscdev);
361 dev_dbg(&pdev->dev, "failed to register wdt miscdev\n");
365 platform_set_drvdata(pdev, wdt);
366 wdt->miscdev.parent = &pdev->dev;
368 "AT32AP700X WDT at 0x%p, timeout %d sec (nowayout=%d)\n",
369 wdt->regs, wdt->timeout, nowayout);
381 static int __exit at32_wdt_remove(struct platform_device *pdev)
383 if (wdt && platform_get_drvdata(pdev) == wdt) {
384 /* Stop the timer before we leave */
388 misc_deregister(&wdt->miscdev);
392 platform_set_drvdata(pdev, NULL);
397 static void at32_wdt_shutdown(struct platform_device *pdev)
403 static int at32_wdt_suspend(struct platform_device *pdev, pm_message_t message)
409 static int at32_wdt_resume(struct platform_device *pdev)
416 #define at32_wdt_suspend NULL
417 #define at32_wdt_resume NULL
420 /* work with hotplug and coldplug */
421 MODULE_ALIAS("platform:at32_wdt");
423 static struct platform_driver at32_wdt_driver = {
424 .remove = __exit_p(at32_wdt_remove),
425 .suspend = at32_wdt_suspend,
426 .resume = at32_wdt_resume,
429 .owner = THIS_MODULE,
431 .shutdown = at32_wdt_shutdown,
434 static int __init at32_wdt_init(void)
436 return platform_driver_probe(&at32_wdt_driver, at32_wdt_probe);
438 module_init(at32_wdt_init);
440 static void __exit at32_wdt_exit(void)
442 platform_driver_unregister(&at32_wdt_driver);
444 module_exit(at32_wdt_exit);
446 MODULE_AUTHOR("Hans-Christian Egtvedt <hcegtvedt@atmel.com>");
447 MODULE_DESCRIPTION("Watchdog driver for Atmel AT32AP700X");
448 MODULE_LICENSE("GPL");
449 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);