4 * Copyright (C) 2008-2009 ST-Ericsson AB
5 * License terms: GNU General Public License (GPL) version 2
6 * Watchdog driver for the ST-Ericsson AB COH 901 327 IP core
7 * Author: Linus Walleij <linus.walleij@stericsson.com>
9 #include <linux/module.h>
10 #include <linux/types.h>
11 #include <linux/watchdog.h>
12 #include <linux/interrupt.h>
14 #include <linux/platform_device.h>
16 #include <linux/bitops.h>
17 #include <linux/clk.h>
18 #include <linux/delay.h>
19 #include <linux/err.h>
21 #define DRV_NAME "WDOG COH 901 327"
24 * COH 901 327 register definitions
27 /* WDOG_FEED Register 32bit (-/W) */
28 #define U300_WDOG_FR 0x00
29 #define U300_WDOG_FR_FEED_RESTART_TIMER 0xFEEDU
30 /* WDOG_TIMEOUT Register 32bit (R/W) */
31 #define U300_WDOG_TR 0x04
32 #define U300_WDOG_TR_TIMEOUT_MASK 0x7FFFU
33 /* WDOG_DISABLE1 Register 32bit (-/W) */
34 #define U300_WDOG_D1R 0x08
35 #define U300_WDOG_D1R_DISABLE1_DISABLE_TIMER 0x2BADU
36 /* WDOG_DISABLE2 Register 32bit (R/W) */
37 #define U300_WDOG_D2R 0x0C
38 #define U300_WDOG_D2R_DISABLE2_DISABLE_TIMER 0xCAFEU
39 #define U300_WDOG_D2R_DISABLE_STATUS_DISABLED 0xDABEU
40 #define U300_WDOG_D2R_DISABLE_STATUS_ENABLED 0x0000U
41 /* WDOG_STATUS Register 32bit (R/W) */
42 #define U300_WDOG_SR 0x10
43 #define U300_WDOG_SR_STATUS_TIMED_OUT 0xCFE8U
44 #define U300_WDOG_SR_STATUS_NORMAL 0x0000U
45 #define U300_WDOG_SR_RESET_STATUS_RESET 0xE8B4U
46 /* WDOG_COUNT Register 32bit (R/-) */
47 #define U300_WDOG_CR 0x14
48 #define U300_WDOG_CR_VALID_IND 0x8000U
49 #define U300_WDOG_CR_VALID_STABLE 0x0000U
50 #define U300_WDOG_CR_COUNT_VALUE_MASK 0x7FFFU
51 /* WDOG_JTAGOVR Register 32bit (R/W) */
52 #define U300_WDOG_JOR 0x18
53 #define U300_WDOG_JOR_JTAG_MODE_IND 0x0002U
54 #define U300_WDOG_JOR_JTAG_WATCHDOG_ENABLE 0x0001U
55 /* WDOG_RESTART Register 32bit (-/W) */
56 #define U300_WDOG_RR 0x1C
57 #define U300_WDOG_RR_RESTART_VALUE_RESUME 0xACEDU
58 /* WDOG_IRQ_EVENT Register 32bit (R/W) */
59 #define U300_WDOG_IER 0x20
60 #define U300_WDOG_IER_WILL_BARK_IRQ_EVENT_IND 0x0001U
61 #define U300_WDOG_IER_WILL_BARK_IRQ_ACK_ENABLE 0x0001U
62 /* WDOG_IRQ_MASK Register 32bit (R/W) */
63 #define U300_WDOG_IMR 0x24
64 #define U300_WDOG_IMR_WILL_BARK_IRQ_ENABLE 0x0001U
65 /* WDOG_IRQ_FORCE Register 32bit (R/W) */
66 #define U300_WDOG_IFR 0x28
67 #define U300_WDOG_IFR_WILL_BARK_IRQ_FORCE_ENABLE 0x0001U
69 /* Default timeout in seconds = 1 minute */
70 static unsigned int margin = 60;
71 static resource_size_t phybase;
72 static resource_size_t physize;
74 static void __iomem *virtbase;
75 static struct device *parent;
77 static struct clk *clk;
80 * Enabling and disabling functions.
82 static void coh901327_enable(u16 timeout)
86 unsigned long delay_ns;
88 /* Restart timer if it is disabled */
89 val = readw(virtbase + U300_WDOG_D2R);
90 if (val == U300_WDOG_D2R_DISABLE_STATUS_DISABLED)
91 writew(U300_WDOG_RR_RESTART_VALUE_RESUME,
92 virtbase + U300_WDOG_RR);
93 /* Acknowledge any pending interrupt so it doesn't just fire off */
94 writew(U300_WDOG_IER_WILL_BARK_IRQ_ACK_ENABLE,
95 virtbase + U300_WDOG_IER);
97 * The interrupt is cleared in the 32 kHz clock domain.
98 * Wait 3 32 kHz cycles for it to take effect
100 freq = clk_get_rate(clk);
101 delay_ns = DIV_ROUND_UP(1000000000, freq); /* Freq to ns and round up */
102 delay_ns = 3 * delay_ns; /* Wait 3 cycles */
104 /* Enable the watchdog interrupt */
105 writew(U300_WDOG_IMR_WILL_BARK_IRQ_ENABLE, virtbase + U300_WDOG_IMR);
106 /* Activate the watchdog timer */
107 writew(timeout, virtbase + U300_WDOG_TR);
108 /* Start the watchdog timer */
109 writew(U300_WDOG_FR_FEED_RESTART_TIMER, virtbase + U300_WDOG_FR);
111 * Extra read so that this change propagate in the watchdog.
113 (void) readw(virtbase + U300_WDOG_CR);
114 val = readw(virtbase + U300_WDOG_D2R);
115 if (val != U300_WDOG_D2R_DISABLE_STATUS_ENABLED)
117 "%s(): watchdog not enabled! D2R value %04x\n",
121 static void coh901327_disable(void)
125 /* Disable the watchdog interrupt if it is active */
126 writew(0x0000U, virtbase + U300_WDOG_IMR);
127 /* If the watchdog is currently enabled, attempt to disable it */
128 val = readw(virtbase + U300_WDOG_D2R);
129 if (val != U300_WDOG_D2R_DISABLE_STATUS_DISABLED) {
130 writew(U300_WDOG_D1R_DISABLE1_DISABLE_TIMER,
131 virtbase + U300_WDOG_D1R);
132 writew(U300_WDOG_D2R_DISABLE2_DISABLE_TIMER,
133 virtbase + U300_WDOG_D2R);
134 /* Write this twice (else problems occur) */
135 writew(U300_WDOG_D2R_DISABLE2_DISABLE_TIMER,
136 virtbase + U300_WDOG_D2R);
138 val = readw(virtbase + U300_WDOG_D2R);
139 if (val != U300_WDOG_D2R_DISABLE_STATUS_DISABLED)
141 "%s(): watchdog not disabled! D2R value %04x\n",
145 static int coh901327_start(struct watchdog_device *wdt_dev)
147 coh901327_enable(wdt_dev->timeout * 100);
151 static int coh901327_stop(struct watchdog_device *wdt_dev)
157 static int coh901327_ping(struct watchdog_device *wdd)
159 /* Feed the watchdog */
160 writew(U300_WDOG_FR_FEED_RESTART_TIMER,
161 virtbase + U300_WDOG_FR);
165 static int coh901327_settimeout(struct watchdog_device *wdt_dev,
168 wdt_dev->timeout = time;
169 /* Set new timeout value */
170 writew(time * 100, virtbase + U300_WDOG_TR);
172 writew(U300_WDOG_FR_FEED_RESTART_TIMER,
173 virtbase + U300_WDOG_FR);
177 static unsigned int coh901327_gettimeleft(struct watchdog_device *wdt_dev)
181 /* Read repeatedly until the value is stable! */
182 val = readw(virtbase + U300_WDOG_CR);
183 while (val & U300_WDOG_CR_VALID_IND)
184 val = readw(virtbase + U300_WDOG_CR);
185 val &= U300_WDOG_CR_COUNT_VALUE_MASK;
193 * This interrupt occurs 10 ms before the watchdog WILL bark.
195 static irqreturn_t coh901327_interrupt(int irq, void *data)
200 * Ack IRQ? If this occurs we're FUBAR anyway, so
201 * just acknowledge, disable the interrupt and await the imminent end.
202 * If you at some point need a host of callbacks to be called
203 * when the system is about to watchdog-reset, add them here!
205 * NOTE: on future versions of this IP-block, it will be possible
206 * to prevent a watchdog reset by feeding the watchdog at this
209 val = readw(virtbase + U300_WDOG_IER);
210 if (val == U300_WDOG_IER_WILL_BARK_IRQ_EVENT_IND)
211 writew(U300_WDOG_IER_WILL_BARK_IRQ_ACK_ENABLE,
212 virtbase + U300_WDOG_IER);
213 writew(0x0000U, virtbase + U300_WDOG_IMR);
214 dev_crit(parent, "watchdog is barking!\n");
218 static const struct watchdog_info coh901327_ident = {
219 .options = WDIOF_CARDRESET | WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING,
220 .identity = DRV_NAME,
223 static struct watchdog_ops coh901327_ops = {
224 .owner = THIS_MODULE,
225 .start = coh901327_start,
226 .stop = coh901327_stop,
227 .ping = coh901327_ping,
228 .set_timeout = coh901327_settimeout,
229 .get_timeleft = coh901327_gettimeleft,
232 static struct watchdog_device coh901327_wdt = {
233 .info = &coh901327_ident,
234 .ops = &coh901327_ops,
236 * Max timeout is 327 since the 10ms
237 * timeout register is max
238 * 0x7FFF = 327670ms ~= 327s.
244 static int __exit coh901327_remove(struct platform_device *pdev)
246 watchdog_unregister_device(&coh901327_wdt);
249 clk_disable_unprepare(clk);
252 release_mem_region(phybase, physize);
256 static int __init coh901327_probe(struct platform_device *pdev)
260 struct resource *res;
262 res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
267 physize = resource_size(res);
268 phybase = res->start;
270 if (request_mem_region(phybase, physize, DRV_NAME) == NULL) {
275 virtbase = ioremap(phybase, physize);
281 clk = clk_get(&pdev->dev, NULL);
284 dev_err(&pdev->dev, "could not get clock\n");
287 ret = clk_prepare_enable(clk);
289 dev_err(&pdev->dev, "could not prepare and enable clock\n");
290 goto out_no_clk_enable;
293 val = readw(virtbase + U300_WDOG_SR);
295 case U300_WDOG_SR_STATUS_TIMED_OUT:
297 "watchdog timed out since last chip reset!\n");
298 coh901327_wdt.bootstatus |= WDIOF_CARDRESET;
299 /* Status will be cleared below */
301 case U300_WDOG_SR_STATUS_NORMAL:
303 "in normal status, no timeouts have occurred.\n");
307 "contains an illegal status code (%08x)\n", val);
311 val = readw(virtbase + U300_WDOG_D2R);
313 case U300_WDOG_D2R_DISABLE_STATUS_DISABLED:
314 dev_info(&pdev->dev, "currently disabled.\n");
316 case U300_WDOG_D2R_DISABLE_STATUS_ENABLED:
318 "currently enabled! (disabling it now)\n");
323 "contains an illegal enable/disable code (%08x)\n",
328 /* Reset the watchdog */
329 writew(U300_WDOG_SR_RESET_STATUS_RESET, virtbase + U300_WDOG_SR);
331 irq = platform_get_irq(pdev, 0);
332 if (request_irq(irq, coh901327_interrupt, 0,
333 DRV_NAME " Bark", pdev)) {
338 ret = watchdog_init_timeout(&coh901327_wdt, margin, &pdev->dev);
340 coh901327_wdt.timeout = 60;
342 coh901327_wdt.parent = &pdev->dev;
343 ret = watchdog_register_device(&coh901327_wdt);
347 dev_info(&pdev->dev, "initialized. timer margin=%d sec\n", margin);
353 clk_disable_unprepare(clk);
359 release_mem_region(phybase, SZ_4K);
366 static u16 wdogenablestore;
367 static u16 irqmaskstore;
369 static int coh901327_suspend(struct platform_device *pdev, pm_message_t state)
371 irqmaskstore = readw(virtbase + U300_WDOG_IMR) & 0x0001U;
372 wdogenablestore = readw(virtbase + U300_WDOG_D2R);
373 /* If watchdog is on, disable it here and now */
374 if (wdogenablestore == U300_WDOG_D2R_DISABLE_STATUS_ENABLED)
379 static int coh901327_resume(struct platform_device *pdev)
381 /* Restore the watchdog interrupt */
382 writew(irqmaskstore, virtbase + U300_WDOG_IMR);
383 if (wdogenablestore == U300_WDOG_D2R_DISABLE_STATUS_ENABLED) {
384 /* Restart the watchdog timer */
385 writew(U300_WDOG_RR_RESTART_VALUE_RESUME,
386 virtbase + U300_WDOG_RR);
387 writew(U300_WDOG_FR_FEED_RESTART_TIMER,
388 virtbase + U300_WDOG_FR);
393 #define coh901327_suspend NULL
394 #define coh901327_resume NULL
398 * Mistreating the watchdog is the only way to perform a software reset of the
399 * system on EMP platforms. So we implement this and export a symbol for it.
401 void coh901327_watchdog_reset(void)
403 /* Enable even if on JTAG too */
404 writew(U300_WDOG_JOR_JTAG_WATCHDOG_ENABLE,
405 virtbase + U300_WDOG_JOR);
407 * Timeout = 5s, we have to wait for the watchdog reset to
408 * actually take place: the watchdog will be reloaded with the
409 * default value immediately, so we HAVE to reboot and get back
410 * into the kernel in 30s, or the device will reboot again!
411 * The boot loader will typically deactivate the watchdog, so we
412 * need time enough for the boot loader to get to the point of
413 * deactivating the watchdog before it is shut down by it.
415 * NOTE: on future versions of the watchdog, this restriction is
416 * gone: the watchdog will be reloaded with a default value (1 min)
417 * instead of last value, and you can conveniently set the watchdog
418 * timeout to 10ms (value = 1) without any problems.
420 coh901327_enable(500);
421 /* Return and await doom */
424 static const struct of_device_id coh901327_dt_match[] = {
425 { .compatible = "stericsson,coh901327" },
429 static struct platform_driver coh901327_driver = {
431 .name = "coh901327_wdog",
432 .of_match_table = coh901327_dt_match,
434 .remove = __exit_p(coh901327_remove),
435 .suspend = coh901327_suspend,
436 .resume = coh901327_resume,
439 module_platform_driver_probe(coh901327_driver, coh901327_probe);
441 MODULE_AUTHOR("Linus Walleij <linus.walleij@stericsson.com>");
442 MODULE_DESCRIPTION("COH 901 327 Watchdog");
444 module_param(margin, uint, 0);
445 MODULE_PARM_DESC(margin, "Watchdog margin in seconds (default 60s)");
447 MODULE_LICENSE("GPL");
448 MODULE_ALIAS("platform:coh901327-watchdog");