1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * Watchdog driver for IMX2 and later processors
4 *
5 * Copyright (C) 2010 Wolfram Sang, Pengutronix e.K. <kernel@pengutronix.de>
6 * Copyright (C) 2014 Freescale Semiconductor, Inc.
7 *
8 * some parts adapted by similar drivers from Darius Augulis and Vladimir
9 * Zapolskiy, additional improvements by Wim Van Sebroeck.
10 *
11 * NOTE: MX1 has a slightly different Watchdog than MX2 and later:
12 *
13 * MX1: MX2+:
14 * ---- -----
15 * Registers: 32-bit 16-bit
16 * Stopable timer: Yes No
17 * Need to enable clk: No Yes
18 * Halt on suspend: Manual Can be automatic
19 */
20
21 #include <linux/clk.h>
22 #include <linux/delay.h>
23 #include <linux/init.h>
24 #include <linux/interrupt.h>
25 #include <linux/io.h>
26 #include <linux/kernel.h>
27 #include <linux/module.h>
28 #include <linux/moduleparam.h>
29 #include <linux/of_address.h>
30 #include <linux/platform_device.h>
31 #include <linux/regmap.h>
32 #include <linux/watchdog.h>
33
34 #define DRIVER_NAME "imx2-wdt"
35
36 #define IMX2_WDT_WCR 0x00 /* Control Register */
37 #define IMX2_WDT_WCR_WT (0xFF << 8) /* -> Watchdog Timeout Field */
38 #define IMX2_WDT_WCR_WDA BIT(5) /* -> External Reset WDOG_B */
39 #define IMX2_WDT_WCR_SRS BIT(4) /* -> Software Reset Signal */
40 #define IMX2_WDT_WCR_WRE BIT(3) /* -> WDOG Reset Enable */
41 #define IMX2_WDT_WCR_WDE BIT(2) /* -> Watchdog Enable */
42 #define IMX2_WDT_WCR_WDZST BIT(0) /* -> Watchdog timer Suspend */
43
44 #define IMX2_WDT_WSR 0x02 /* Service Register */
45 #define IMX2_WDT_SEQ1 0x5555 /* -> service sequence 1 */
46 #define IMX2_WDT_SEQ2 0xAAAA /* -> service sequence 2 */
47
48 #define IMX2_WDT_WRSR 0x04 /* Reset Status Register */
49 #define IMX2_WDT_WRSR_TOUT BIT(1) /* -> Reset due to Timeout */
50
51 #define IMX2_WDT_WICR 0x06 /* Interrupt Control Register */
52 #define IMX2_WDT_WICR_WIE BIT(15) /* -> Interrupt Enable */
53 #define IMX2_WDT_WICR_WTIS BIT(14) /* -> Interrupt Status */
54 #define IMX2_WDT_WICR_WICT 0xFF /* -> Interrupt Count Timeout */
55
56 #define IMX2_WDT_WMCR 0x08 /* Misc Register */
57
58 #define IMX2_WDT_MAX_TIME 128U
59 #define IMX2_WDT_DEFAULT_TIME 60 /* in seconds */
60
61 #define WDOG_SEC_TO_COUNT(s) ((s * 2 - 1) << 8)
62
63 struct imx2_wdt_device {
64 struct clk *clk;
65 struct regmap *regmap;
66 struct watchdog_device wdog;
67 bool ext_reset;
68 bool clk_is_on;
69 bool no_ping;
70 };
71
72 static bool nowayout = WATCHDOG_NOWAYOUT;
73 module_param(nowayout, bool, 0);
74 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
75 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
76
77 static unsigned timeout;
78 module_param(timeout, uint, 0);
79 MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds (default="
80 __MODULE_STRING(IMX2_WDT_DEFAULT_TIME) ")");
81
82 static const struct watchdog_info imx2_wdt_info = {
83 .identity = "imx2+ watchdog",
84 .options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE,
85 };
86
87 static const struct watchdog_info imx2_wdt_pretimeout_info = {
88 .identity = "imx2+ watchdog",
89 .options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE |
90 WDIOF_PRETIMEOUT,
91 };
92
imx2_wdt_restart(struct watchdog_device * wdog,unsigned long action,void * data)93 static int imx2_wdt_restart(struct watchdog_device *wdog, unsigned long action,
94 void *data)
95 {
96 struct imx2_wdt_device *wdev = watchdog_get_drvdata(wdog);
97 unsigned int wcr_enable = IMX2_WDT_WCR_WDE;
98
99 /* Use internal reset or external - not both */
100 if (wdev->ext_reset)
101 wcr_enable |= IMX2_WDT_WCR_SRS; /* do not assert int reset */
102 else
103 wcr_enable |= IMX2_WDT_WCR_WDA; /* do not assert ext-reset */
104
105 /* Assert SRS signal */
106 regmap_write(wdev->regmap, IMX2_WDT_WCR, wcr_enable);
107 /*
108 * Due to imx6q errata ERR004346 (WDOG: WDOG SRS bit requires to be
109 * written twice), we add another two writes to ensure there must be at
110 * least two writes happen in the same one 32kHz clock period. We save
111 * the target check here, since the writes shouldn't be a huge burden
112 * for other platforms.
113 */
114 regmap_write(wdev->regmap, IMX2_WDT_WCR, wcr_enable);
115 regmap_write(wdev->regmap, IMX2_WDT_WCR, wcr_enable);
116
117 /* wait for reset to assert... */
118 mdelay(500);
119
120 return 0;
121 }
122
imx2_wdt_setup(struct watchdog_device * wdog)123 static inline void imx2_wdt_setup(struct watchdog_device *wdog)
124 {
125 struct imx2_wdt_device *wdev = watchdog_get_drvdata(wdog);
126 u32 val;
127
128 regmap_read(wdev->regmap, IMX2_WDT_WCR, &val);
129
130 /* Suspend timer in low power mode, write once-only */
131 val |= IMX2_WDT_WCR_WDZST;
132 /* Strip the old watchdog Time-Out value */
133 val &= ~IMX2_WDT_WCR_WT;
134 /* Generate internal chip-level reset if WDOG times out */
135 if (!wdev->ext_reset)
136 val &= ~IMX2_WDT_WCR_WRE;
137 /* Or if external-reset assert WDOG_B reset only on time-out */
138 else
139 val |= IMX2_WDT_WCR_WRE;
140 /* Keep Watchdog Disabled */
141 val &= ~IMX2_WDT_WCR_WDE;
142 /* Set the watchdog's Time-Out value */
143 val |= WDOG_SEC_TO_COUNT(wdog->timeout);
144
145 regmap_write(wdev->regmap, IMX2_WDT_WCR, val);
146
147 /* enable the watchdog */
148 val |= IMX2_WDT_WCR_WDE;
149 regmap_write(wdev->regmap, IMX2_WDT_WCR, val);
150 }
151
imx2_wdt_is_running(struct imx2_wdt_device * wdev)152 static inline bool imx2_wdt_is_running(struct imx2_wdt_device *wdev)
153 {
154 u32 val;
155
156 regmap_read(wdev->regmap, IMX2_WDT_WCR, &val);
157
158 return val & IMX2_WDT_WCR_WDE;
159 }
160
imx2_wdt_ping(struct watchdog_device * wdog)161 static int imx2_wdt_ping(struct watchdog_device *wdog)
162 {
163 struct imx2_wdt_device *wdev = watchdog_get_drvdata(wdog);
164
165 if (!wdev->clk_is_on)
166 return 0;
167
168 regmap_write(wdev->regmap, IMX2_WDT_WSR, IMX2_WDT_SEQ1);
169 regmap_write(wdev->regmap, IMX2_WDT_WSR, IMX2_WDT_SEQ2);
170 return 0;
171 }
172
__imx2_wdt_set_timeout(struct watchdog_device * wdog,unsigned int new_timeout)173 static void __imx2_wdt_set_timeout(struct watchdog_device *wdog,
174 unsigned int new_timeout)
175 {
176 struct imx2_wdt_device *wdev = watchdog_get_drvdata(wdog);
177
178 regmap_update_bits(wdev->regmap, IMX2_WDT_WCR, IMX2_WDT_WCR_WT,
179 WDOG_SEC_TO_COUNT(new_timeout));
180 }
181
imx2_wdt_set_timeout(struct watchdog_device * wdog,unsigned int new_timeout)182 static int imx2_wdt_set_timeout(struct watchdog_device *wdog,
183 unsigned int new_timeout)
184 {
185 unsigned int actual;
186
187 actual = min(new_timeout, IMX2_WDT_MAX_TIME);
188 __imx2_wdt_set_timeout(wdog, actual);
189 wdog->timeout = new_timeout;
190 return 0;
191 }
192
imx2_wdt_set_pretimeout(struct watchdog_device * wdog,unsigned int new_pretimeout)193 static int imx2_wdt_set_pretimeout(struct watchdog_device *wdog,
194 unsigned int new_pretimeout)
195 {
196 struct imx2_wdt_device *wdev = watchdog_get_drvdata(wdog);
197
198 if (new_pretimeout >= IMX2_WDT_MAX_TIME)
199 return -EINVAL;
200
201 wdog->pretimeout = new_pretimeout;
202
203 regmap_update_bits(wdev->regmap, IMX2_WDT_WICR,
204 IMX2_WDT_WICR_WIE | IMX2_WDT_WICR_WICT,
205 IMX2_WDT_WICR_WIE | (new_pretimeout << 1));
206 return 0;
207 }
208
imx2_wdt_isr(int irq,void * wdog_arg)209 static irqreturn_t imx2_wdt_isr(int irq, void *wdog_arg)
210 {
211 struct watchdog_device *wdog = wdog_arg;
212 struct imx2_wdt_device *wdev = watchdog_get_drvdata(wdog);
213
214 regmap_write_bits(wdev->regmap, IMX2_WDT_WICR,
215 IMX2_WDT_WICR_WTIS, IMX2_WDT_WICR_WTIS);
216
217 watchdog_notify_pretimeout(wdog);
218
219 return IRQ_HANDLED;
220 }
221
imx2_wdt_start(struct watchdog_device * wdog)222 static int imx2_wdt_start(struct watchdog_device *wdog)
223 {
224 struct imx2_wdt_device *wdev = watchdog_get_drvdata(wdog);
225
226 if (imx2_wdt_is_running(wdev))
227 imx2_wdt_set_timeout(wdog, wdog->timeout);
228 else
229 imx2_wdt_setup(wdog);
230
231 set_bit(WDOG_HW_RUNNING, &wdog->status);
232
233 return imx2_wdt_ping(wdog);
234 }
235
236 static const struct watchdog_ops imx2_wdt_ops = {
237 .owner = THIS_MODULE,
238 .start = imx2_wdt_start,
239 .ping = imx2_wdt_ping,
240 .set_timeout = imx2_wdt_set_timeout,
241 .set_pretimeout = imx2_wdt_set_pretimeout,
242 .restart = imx2_wdt_restart,
243 };
244
245 static const struct regmap_config imx2_wdt_regmap_config = {
246 .reg_bits = 16,
247 .reg_stride = 2,
248 .val_bits = 16,
249 .max_register = 0x8,
250 };
251
imx2_wdt_action(void * data)252 static void imx2_wdt_action(void *data)
253 {
254 clk_disable_unprepare(data);
255 }
256
imx2_wdt_probe(struct platform_device * pdev)257 static int __init imx2_wdt_probe(struct platform_device *pdev)
258 {
259 struct device *dev = &pdev->dev;
260 struct imx2_wdt_device *wdev;
261 struct watchdog_device *wdog;
262 void __iomem *base;
263 int ret;
264 u32 val;
265
266 wdev = devm_kzalloc(dev, sizeof(*wdev), GFP_KERNEL);
267 if (!wdev)
268 return -ENOMEM;
269
270 base = devm_platform_ioremap_resource(pdev, 0);
271 if (IS_ERR(base))
272 return PTR_ERR(base);
273
274 wdev->regmap = devm_regmap_init_mmio_clk(dev, NULL, base,
275 &imx2_wdt_regmap_config);
276 if (IS_ERR(wdev->regmap)) {
277 dev_err(dev, "regmap init failed\n");
278 return PTR_ERR(wdev->regmap);
279 }
280
281 wdev->clk = devm_clk_get(dev, NULL);
282 if (IS_ERR(wdev->clk)) {
283 dev_err(dev, "can't get Watchdog clock\n");
284 return PTR_ERR(wdev->clk);
285 }
286
287 wdog = &wdev->wdog;
288 wdog->info = &imx2_wdt_info;
289 wdog->ops = &imx2_wdt_ops;
290 wdog->min_timeout = 1;
291 wdog->timeout = IMX2_WDT_DEFAULT_TIME;
292 wdog->max_hw_heartbeat_ms = IMX2_WDT_MAX_TIME * 1000;
293 wdog->parent = dev;
294
295 ret = platform_get_irq(pdev, 0);
296 if (ret > 0)
297 if (!devm_request_irq(dev, ret, imx2_wdt_isr, 0,
298 dev_name(dev), wdog))
299 wdog->info = &imx2_wdt_pretimeout_info;
300
301 ret = clk_prepare_enable(wdev->clk);
302 if (ret)
303 return ret;
304
305 ret = devm_add_action_or_reset(dev, imx2_wdt_action, wdev->clk);
306 if (ret)
307 return ret;
308
309 wdev->clk_is_on = true;
310
311 regmap_read(wdev->regmap, IMX2_WDT_WRSR, &val);
312 wdog->bootstatus = val & IMX2_WDT_WRSR_TOUT ? WDIOF_CARDRESET : 0;
313
314 wdev->ext_reset = of_property_read_bool(dev->of_node,
315 "fsl,ext-reset-output");
316 /*
317 * The i.MX7D doesn't support low power mode, so we need to ping the watchdog
318 * during suspend.
319 */
320 wdev->no_ping = !of_device_is_compatible(dev->of_node, "fsl,imx7d-wdt");
321 platform_set_drvdata(pdev, wdog);
322 watchdog_set_drvdata(wdog, wdev);
323 watchdog_set_nowayout(wdog, nowayout);
324 watchdog_set_restart_priority(wdog, 128);
325 watchdog_init_timeout(wdog, timeout, dev);
326 if (wdev->no_ping)
327 watchdog_stop_ping_on_suspend(wdog);
328
329 if (imx2_wdt_is_running(wdev)) {
330 imx2_wdt_set_timeout(wdog, wdog->timeout);
331 set_bit(WDOG_HW_RUNNING, &wdog->status);
332 }
333
334 /*
335 * Disable the watchdog power down counter at boot. Otherwise the power
336 * down counter will pull down the #WDOG interrupt line for one clock
337 * cycle.
338 */
339 regmap_write(wdev->regmap, IMX2_WDT_WMCR, 0);
340
341 return devm_watchdog_register_device(dev, wdog);
342 }
343
imx2_wdt_shutdown(struct platform_device * pdev)344 static void imx2_wdt_shutdown(struct platform_device *pdev)
345 {
346 struct watchdog_device *wdog = platform_get_drvdata(pdev);
347 struct imx2_wdt_device *wdev = watchdog_get_drvdata(wdog);
348
349 if (imx2_wdt_is_running(wdev)) {
350 /*
351 * We are running, configure max timeout before reboot
352 * will take place.
353 */
354 imx2_wdt_set_timeout(wdog, IMX2_WDT_MAX_TIME);
355 imx2_wdt_ping(wdog);
356 dev_crit(&pdev->dev, "Device shutdown: Expect reboot!\n");
357 }
358 }
359
360 /* Disable watchdog if it is active or non-active but still running */
imx2_wdt_suspend(struct device * dev)361 static int __maybe_unused imx2_wdt_suspend(struct device *dev)
362 {
363 struct watchdog_device *wdog = dev_get_drvdata(dev);
364 struct imx2_wdt_device *wdev = watchdog_get_drvdata(wdog);
365
366 /* The watchdog IP block is running */
367 if (imx2_wdt_is_running(wdev)) {
368 /*
369 * Don't update wdog->timeout, we'll restore the current value
370 * during resume.
371 */
372 __imx2_wdt_set_timeout(wdog, IMX2_WDT_MAX_TIME);
373 imx2_wdt_ping(wdog);
374 }
375
376 if (wdev->no_ping) {
377 clk_disable_unprepare(wdev->clk);
378
379 wdev->clk_is_on = false;
380 }
381
382 return 0;
383 }
384
385 /* Enable watchdog and configure it if necessary */
imx2_wdt_resume(struct device * dev)386 static int __maybe_unused imx2_wdt_resume(struct device *dev)
387 {
388 struct watchdog_device *wdog = dev_get_drvdata(dev);
389 struct imx2_wdt_device *wdev = watchdog_get_drvdata(wdog);
390 int ret;
391
392 if (wdev->no_ping) {
393 ret = clk_prepare_enable(wdev->clk);
394
395 if (ret)
396 return ret;
397
398 wdev->clk_is_on = true;
399 }
400
401 if (watchdog_active(wdog) && !imx2_wdt_is_running(wdev)) {
402 /*
403 * If the watchdog is still active and resumes
404 * from deep sleep state, need to restart the
405 * watchdog again.
406 */
407 imx2_wdt_setup(wdog);
408 }
409 if (imx2_wdt_is_running(wdev)) {
410 imx2_wdt_set_timeout(wdog, wdog->timeout);
411 imx2_wdt_ping(wdog);
412 }
413
414 return 0;
415 }
416
417 static SIMPLE_DEV_PM_OPS(imx2_wdt_pm_ops, imx2_wdt_suspend,
418 imx2_wdt_resume);
419
420 static const struct of_device_id imx2_wdt_dt_ids[] = {
421 { .compatible = "fsl,imx21-wdt", },
422 { .compatible = "fsl,imx7d-wdt", },
423 { /* sentinel */ }
424 };
425 MODULE_DEVICE_TABLE(of, imx2_wdt_dt_ids);
426
427 static struct platform_driver imx2_wdt_driver = {
428 .shutdown = imx2_wdt_shutdown,
429 .driver = {
430 .name = DRIVER_NAME,
431 .pm = &imx2_wdt_pm_ops,
432 .of_match_table = imx2_wdt_dt_ids,
433 },
434 };
435
436 module_platform_driver_probe(imx2_wdt_driver, imx2_wdt_probe);
437
438 MODULE_AUTHOR("Wolfram Sang");
439 MODULE_DESCRIPTION("Watchdog driver for IMX2 and later");
440 MODULE_LICENSE("GPL v2");
441 MODULE_ALIAS("platform:" DRIVER_NAME);
442
