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1// SPDX-License-Identifier: GPL-2.0
2/*
3 * coh901327_wdt.c
4 *
5 * Copyright (C) 2008-2009 ST-Ericsson AB
6 * Watchdog driver for the ST-Ericsson AB COH 901 327 IP core
7 * Author: Linus Walleij <linus.walleij@stericsson.com>
8 */
9#include <linux/moduleparam.h>
10#include <linux/mod_devicetable.h>
11#include <linux/types.h>
12#include <linux/watchdog.h>
13#include <linux/interrupt.h>
14#include <linux/pm.h>
15#include <linux/platform_device.h>
16#include <linux/io.h>
17#include <linux/bitops.h>
18#include <linux/clk.h>
19#include <linux/delay.h>
20#include <linux/err.h>
21
22#define DRV_NAME "WDOG COH 901 327"
23
24/*
25 * COH 901 327 register definitions
26 */
27
28/* WDOG_FEED Register 32bit (-/W) */
29#define U300_WDOG_FR 0x00
30#define U300_WDOG_FR_FEED_RESTART_TIMER 0xFEEDU
31/* WDOG_TIMEOUT Register 32bit (R/W) */
32#define U300_WDOG_TR 0x04
33#define U300_WDOG_TR_TIMEOUT_MASK 0x7FFFU
34/* WDOG_DISABLE1 Register 32bit (-/W) */
35#define U300_WDOG_D1R 0x08
36#define U300_WDOG_D1R_DISABLE1_DISABLE_TIMER 0x2BADU
37/* WDOG_DISABLE2 Register 32bit (R/W) */
38#define U300_WDOG_D2R 0x0C
39#define U300_WDOG_D2R_DISABLE2_DISABLE_TIMER 0xCAFEU
40#define U300_WDOG_D2R_DISABLE_STATUS_DISABLED 0xDABEU
41#define U300_WDOG_D2R_DISABLE_STATUS_ENABLED 0x0000U
42/* WDOG_STATUS Register 32bit (R/W) */
43#define U300_WDOG_SR 0x10
44#define U300_WDOG_SR_STATUS_TIMED_OUT 0xCFE8U
45#define U300_WDOG_SR_STATUS_NORMAL 0x0000U
46#define U300_WDOG_SR_RESET_STATUS_RESET 0xE8B4U
47/* WDOG_COUNT Register 32bit (R/-) */
48#define U300_WDOG_CR 0x14
49#define U300_WDOG_CR_VALID_IND 0x8000U
50#define U300_WDOG_CR_VALID_STABLE 0x0000U
51#define U300_WDOG_CR_COUNT_VALUE_MASK 0x7FFFU
52/* WDOG_JTAGOVR Register 32bit (R/W) */
53#define U300_WDOG_JOR 0x18
54#define U300_WDOG_JOR_JTAG_MODE_IND 0x0002U
55#define U300_WDOG_JOR_JTAG_WATCHDOG_ENABLE 0x0001U
56/* WDOG_RESTART Register 32bit (-/W) */
57#define U300_WDOG_RR 0x1C
58#define U300_WDOG_RR_RESTART_VALUE_RESUME 0xACEDU
59/* WDOG_IRQ_EVENT Register 32bit (R/W) */
60#define U300_WDOG_IER 0x20
61#define U300_WDOG_IER_WILL_BARK_IRQ_EVENT_IND 0x0001U
62#define U300_WDOG_IER_WILL_BARK_IRQ_ACK_ENABLE 0x0001U
63/* WDOG_IRQ_MASK Register 32bit (R/W) */
64#define U300_WDOG_IMR 0x24
65#define U300_WDOG_IMR_WILL_BARK_IRQ_ENABLE 0x0001U
66/* WDOG_IRQ_FORCE Register 32bit (R/W) */
67#define U300_WDOG_IFR 0x28
68#define U300_WDOG_IFR_WILL_BARK_IRQ_FORCE_ENABLE 0x0001U
69
70/* Default timeout in seconds = 1 minute */
71#define U300_WDOG_DEFAULT_TIMEOUT 60
72
73static unsigned int margin;
74static int irq;
75static void __iomem *virtbase;
76static struct device *parent;
77
78static struct clk *clk;
79
80/*
81 * Enabling and disabling functions.
82 */
83static void coh901327_enable(u16 timeout)
84{
85 u16 val;
86 unsigned long freq;
87 unsigned long delay_ns;
88
89 /* Restart timer if it is disabled */
90 val = readw(virtbase + U300_WDOG_D2R);
91 if (val == U300_WDOG_D2R_DISABLE_STATUS_DISABLED)
92 writew(U300_WDOG_RR_RESTART_VALUE_RESUME,
93 virtbase + U300_WDOG_RR);
94 /* Acknowledge any pending interrupt so it doesn't just fire off */
95 writew(U300_WDOG_IER_WILL_BARK_IRQ_ACK_ENABLE,
96 virtbase + U300_WDOG_IER);
97 /*
98 * The interrupt is cleared in the 32 kHz clock domain.
99 * Wait 3 32 kHz cycles for it to take effect
100 */
101 freq = clk_get_rate(clk);
102 delay_ns = DIV_ROUND_UP(1000000000, freq); /* Freq to ns and round up */
103 delay_ns = 3 * delay_ns; /* Wait 3 cycles */
104 ndelay(delay_ns);
105 /* Enable the watchdog interrupt */
106 writew(U300_WDOG_IMR_WILL_BARK_IRQ_ENABLE, virtbase + U300_WDOG_IMR);
107 /* Activate the watchdog timer */
108 writew(timeout, virtbase + U300_WDOG_TR);
109 /* Start the watchdog timer */
110 writew(U300_WDOG_FR_FEED_RESTART_TIMER, virtbase + U300_WDOG_FR);
111 /*
112 * Extra read so that this change propagate in the watchdog.
113 */
114 (void) readw(virtbase + U300_WDOG_CR);
115 val = readw(virtbase + U300_WDOG_D2R);
116 if (val != U300_WDOG_D2R_DISABLE_STATUS_ENABLED)
117 dev_err(parent,
118 "%s(): watchdog not enabled! D2R value %04x\n",
119 __func__, val);
120}
121
122static void coh901327_disable(void)
123{
124 u16 val;
125
126 /* Disable the watchdog interrupt if it is active */
127 writew(0x0000U, virtbase + U300_WDOG_IMR);
128 /* If the watchdog is currently enabled, attempt to disable it */
129 val = readw(virtbase + U300_WDOG_D2R);
130 if (val != U300_WDOG_D2R_DISABLE_STATUS_DISABLED) {
131 writew(U300_WDOG_D1R_DISABLE1_DISABLE_TIMER,
132 virtbase + U300_WDOG_D1R);
133 writew(U300_WDOG_D2R_DISABLE2_DISABLE_TIMER,
134 virtbase + U300_WDOG_D2R);
135 /* Write this twice (else problems occur) */
136 writew(U300_WDOG_D2R_DISABLE2_DISABLE_TIMER,
137 virtbase + U300_WDOG_D2R);
138 }
139 val = readw(virtbase + U300_WDOG_D2R);
140 if (val != U300_WDOG_D2R_DISABLE_STATUS_DISABLED)
141 dev_err(parent,
142 "%s(): watchdog not disabled! D2R value %04x\n",
143 __func__, val);
144}
145
146static int coh901327_start(struct watchdog_device *wdt_dev)
147{
148 coh901327_enable(wdt_dev->timeout * 100);
149 return 0;
150}
151
152static int coh901327_stop(struct watchdog_device *wdt_dev)
153{
154 coh901327_disable();
155 return 0;
156}
157
158static int coh901327_ping(struct watchdog_device *wdd)
159{
160 /* Feed the watchdog */
161 writew(U300_WDOG_FR_FEED_RESTART_TIMER,
162 virtbase + U300_WDOG_FR);
163 return 0;
164}
165
166static int coh901327_settimeout(struct watchdog_device *wdt_dev,
167 unsigned int time)
168{
169 wdt_dev->timeout = time;
170 /* Set new timeout value */
171 writew(time * 100, virtbase + U300_WDOG_TR);
172 /* Feed the dog */
173 writew(U300_WDOG_FR_FEED_RESTART_TIMER,
174 virtbase + U300_WDOG_FR);
175 return 0;
176}
177
178static unsigned int coh901327_gettimeleft(struct watchdog_device *wdt_dev)
179{
180 u16 val;
181
182 /* Read repeatedly until the value is stable! */
183 val = readw(virtbase + U300_WDOG_CR);
184 while (val & U300_WDOG_CR_VALID_IND)
185 val = readw(virtbase + U300_WDOG_CR);
186 val &= U300_WDOG_CR_COUNT_VALUE_MASK;
187 if (val != 0)
188 val /= 100;
189
190 return val;
191}
192
193/*
194 * This interrupt occurs 10 ms before the watchdog WILL bark.
195 */
196static irqreturn_t coh901327_interrupt(int irq, void *data)
197{
198 u16 val;
199
200 /*
201 * Ack IRQ? If this occurs we're FUBAR anyway, so
202 * just acknowledge, disable the interrupt and await the imminent end.
203 * If you at some point need a host of callbacks to be called
204 * when the system is about to watchdog-reset, add them here!
205 *
206 * NOTE: on future versions of this IP-block, it will be possible
207 * to prevent a watchdog reset by feeding the watchdog at this
208 * point.
209 */
210 val = readw(virtbase + U300_WDOG_IER);
211 if (val == U300_WDOG_IER_WILL_BARK_IRQ_EVENT_IND)
212 writew(U300_WDOG_IER_WILL_BARK_IRQ_ACK_ENABLE,
213 virtbase + U300_WDOG_IER);
214 writew(0x0000U, virtbase + U300_WDOG_IMR);
215 dev_crit(parent, "watchdog is barking!\n");
216 return IRQ_HANDLED;
217}
218
219static const struct watchdog_info coh901327_ident = {
220 .options = WDIOF_CARDRESET | WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING,
221 .identity = DRV_NAME,
222};
223
224static const struct watchdog_ops coh901327_ops = {
225 .owner = THIS_MODULE,
226 .start = coh901327_start,
227 .stop = coh901327_stop,
228 .ping = coh901327_ping,
229 .set_timeout = coh901327_settimeout,
230 .get_timeleft = coh901327_gettimeleft,
231};
232
233static struct watchdog_device coh901327_wdt = {
234 .info = &coh901327_ident,
235 .ops = &coh901327_ops,
236 /*
237 * Max timeout is 327 since the 10ms
238 * timeout register is max
239 * 0x7FFF = 327670ms ~= 327s.
240 */
241 .min_timeout = 1,
242 .max_timeout = 327,
243 .timeout = U300_WDOG_DEFAULT_TIMEOUT,
244};
245
246static int __init coh901327_probe(struct platform_device *pdev)
247{
248 struct device *dev = &pdev->dev;
249 int ret;
250 u16 val;
251
252 parent = dev;
253
254 virtbase = devm_platform_ioremap_resource(pdev, 0);
255 if (IS_ERR(virtbase))
256 return PTR_ERR(virtbase);
257
258 clk = clk_get(dev, NULL);
259 if (IS_ERR(clk)) {
260 ret = PTR_ERR(clk);
261 dev_err(dev, "could not get clock\n");
262 return ret;
263 }
264 ret = clk_prepare_enable(clk);
265 if (ret) {
266 dev_err(dev, "could not prepare and enable clock\n");
267 goto out_no_clk_enable;
268 }
269
270 val = readw(virtbase + U300_WDOG_SR);
271 switch (val) {
272 case U300_WDOG_SR_STATUS_TIMED_OUT:
273 dev_info(dev, "watchdog timed out since last chip reset!\n");
274 coh901327_wdt.bootstatus |= WDIOF_CARDRESET;
275 /* Status will be cleared below */
276 break;
277 case U300_WDOG_SR_STATUS_NORMAL:
278 dev_info(dev, "in normal status, no timeouts have occurred.\n");
279 break;
280 default:
281 dev_info(dev, "contains an illegal status code (%08x)\n", val);
282 break;
283 }
284
285 val = readw(virtbase + U300_WDOG_D2R);
286 switch (val) {
287 case U300_WDOG_D2R_DISABLE_STATUS_DISABLED:
288 dev_info(dev, "currently disabled.\n");
289 break;
290 case U300_WDOG_D2R_DISABLE_STATUS_ENABLED:
291 dev_info(dev, "currently enabled! (disabling it now)\n");
292 coh901327_disable();
293 break;
294 default:
295 dev_err(dev, "contains an illegal enable/disable code (%08x)\n",
296 val);
297 break;
298 }
299
300 /* Reset the watchdog */
301 writew(U300_WDOG_SR_RESET_STATUS_RESET, virtbase + U300_WDOG_SR);
302
303 irq = platform_get_irq(pdev, 0);
304 if (request_irq(irq, coh901327_interrupt, 0,
305 DRV_NAME " Bark", pdev)) {
306 ret = -EIO;
307 goto out_no_irq;
308 }
309
310 watchdog_init_timeout(&coh901327_wdt, margin, dev);
311
312 coh901327_wdt.parent = dev;
313 ret = watchdog_register_device(&coh901327_wdt);
314 if (ret)
315 goto out_no_wdog;
316
317 dev_info(dev, "initialized. (timeout=%d sec)\n",
318 coh901327_wdt.timeout);
319 return 0;
320
321out_no_wdog:
322 free_irq(irq, pdev);
323out_no_irq:
324 clk_disable_unprepare(clk);
325out_no_clk_enable:
326 clk_put(clk);
327 return ret;
328}
329
330#ifdef CONFIG_PM
331
332static u16 wdogenablestore;
333static u16 irqmaskstore;
334
335static int coh901327_suspend(struct platform_device *pdev, pm_message_t state)
336{
337 irqmaskstore = readw(virtbase + U300_WDOG_IMR) & 0x0001U;
338 wdogenablestore = readw(virtbase + U300_WDOG_D2R);
339 /* If watchdog is on, disable it here and now */
340 if (wdogenablestore == U300_WDOG_D2R_DISABLE_STATUS_ENABLED)
341 coh901327_disable();
342 return 0;
343}
344
345static int coh901327_resume(struct platform_device *pdev)
346{
347 /* Restore the watchdog interrupt */
348 writew(irqmaskstore, virtbase + U300_WDOG_IMR);
349 if (wdogenablestore == U300_WDOG_D2R_DISABLE_STATUS_ENABLED) {
350 /* Restart the watchdog timer */
351 writew(U300_WDOG_RR_RESTART_VALUE_RESUME,
352 virtbase + U300_WDOG_RR);
353 writew(U300_WDOG_FR_FEED_RESTART_TIMER,
354 virtbase + U300_WDOG_FR);
355 }
356 return 0;
357}
358#else
359#define coh901327_suspend NULL
360#define coh901327_resume NULL
361#endif
362
363/*
364 * Mistreating the watchdog is the only way to perform a software reset of the
365 * system on EMP platforms. So we implement this and export a symbol for it.
366 */
367void coh901327_watchdog_reset(void)
368{
369 /* Enable even if on JTAG too */
370 writew(U300_WDOG_JOR_JTAG_WATCHDOG_ENABLE,
371 virtbase + U300_WDOG_JOR);
372 /*
373 * Timeout = 5s, we have to wait for the watchdog reset to
374 * actually take place: the watchdog will be reloaded with the
375 * default value immediately, so we HAVE to reboot and get back
376 * into the kernel in 30s, or the device will reboot again!
377 * The boot loader will typically deactivate the watchdog, so we
378 * need time enough for the boot loader to get to the point of
379 * deactivating the watchdog before it is shut down by it.
380 *
381 * NOTE: on future versions of the watchdog, this restriction is
382 * gone: the watchdog will be reloaded with a default value (1 min)
383 * instead of last value, and you can conveniently set the watchdog
384 * timeout to 10ms (value = 1) without any problems.
385 */
386 coh901327_enable(500);
387 /* Return and await doom */
388}
389
390static const struct of_device_id coh901327_dt_match[] = {
391 { .compatible = "stericsson,coh901327" },
392 {},
393};
394
395static struct platform_driver coh901327_driver = {
396 .driver = {
397 .name = "coh901327_wdog",
398 .of_match_table = coh901327_dt_match,
399 .suppress_bind_attrs = true,
400 },
401 .suspend = coh901327_suspend,
402 .resume = coh901327_resume,
403};
404builtin_platform_driver_probe(coh901327_driver, coh901327_probe);
405
406/* not really modular, but ... */
407module_param(margin, uint, 0);
408MODULE_PARM_DESC(margin, "Watchdog margin in seconds (default 60s)");