xref: /openbmc/linux/drivers/watchdog/imx2_wdt.c (revision 86db9f28) 
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. <w.sang@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 };
69 
70 static bool nowayout = WATCHDOG_NOWAYOUT;
71 module_param(nowayout, bool, 0);
72 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
73 				__MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
74 
75 
76 static unsigned timeout;
77 module_param(timeout, uint, 0);
78 MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds (default="
79 				__MODULE_STRING(IMX2_WDT_DEFAULT_TIME) ")");
80 
81 static const struct watchdog_info imx2_wdt_info = {
82 	.identity = "imx2+ watchdog",
83 	.options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE,
84 };
85 
86 static const struct watchdog_info imx2_wdt_pretimeout_info = {
87 	.identity = "imx2+ watchdog",
88 	.options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE |
89 		   WDIOF_PRETIMEOUT,
90 };
91 
92 static int imx2_wdt_restart(struct watchdog_device *wdog, unsigned long action,
93 			    void *data)
94 {
95 	struct imx2_wdt_device *wdev = watchdog_get_drvdata(wdog);
96 	unsigned int wcr_enable = IMX2_WDT_WCR_WDE;
97 
98 	/* Use internal reset or external - not both */
99 	if (wdev->ext_reset)
100 		wcr_enable |= IMX2_WDT_WCR_SRS; /* do not assert int reset */
101 	else
102 		wcr_enable |= IMX2_WDT_WCR_WDA; /* do not assert ext-reset */
103 
104 	/* Assert SRS signal */
105 	regmap_write(wdev->regmap, IMX2_WDT_WCR, wcr_enable);
106 	/*
107 	 * Due to imx6q errata ERR004346 (WDOG: WDOG SRS bit requires to be
108 	 * written twice), we add another two writes to ensure there must be at
109 	 * least two writes happen in the same one 32kHz clock period.  We save
110 	 * the target check here, since the writes shouldn't be a huge burden
111 	 * for other platforms.
112 	 */
113 	regmap_write(wdev->regmap, IMX2_WDT_WCR, wcr_enable);
114 	regmap_write(wdev->regmap, IMX2_WDT_WCR, wcr_enable);
115 
116 	/* wait for reset to assert... */
117 	mdelay(500);
118 
119 	return 0;
120 }
121 
122 static inline void imx2_wdt_setup(struct watchdog_device *wdog)
123 {
124 	struct imx2_wdt_device *wdev = watchdog_get_drvdata(wdog);
125 	u32 val;
126 
127 	regmap_read(wdev->regmap, IMX2_WDT_WCR, &val);
128 
129 	/* Suspend timer in low power mode, write once-only */
130 	val |= IMX2_WDT_WCR_WDZST;
131 	/* Strip the old watchdog Time-Out value */
132 	val &= ~IMX2_WDT_WCR_WT;
133 	/* Generate internal chip-level reset if WDOG times out */
134 	if (!wdev->ext_reset)
135 		val &= ~IMX2_WDT_WCR_WRE;
136 	/* Or if external-reset assert WDOG_B reset only on time-out */
137 	else
138 		val |= IMX2_WDT_WCR_WRE;
139 	/* Keep Watchdog Disabled */
140 	val &= ~IMX2_WDT_WCR_WDE;
141 	/* Set the watchdog's Time-Out value */
142 	val |= WDOG_SEC_TO_COUNT(wdog->timeout);
143 
144 	regmap_write(wdev->regmap, IMX2_WDT_WCR, val);
145 
146 	/* enable the watchdog */
147 	val |= IMX2_WDT_WCR_WDE;
148 	regmap_write(wdev->regmap, IMX2_WDT_WCR, val);
149 }
150 
151 static inline bool imx2_wdt_is_running(struct imx2_wdt_device *wdev)
152 {
153 	u32 val;
154 
155 	regmap_read(wdev->regmap, IMX2_WDT_WCR, &val);
156 
157 	return val & IMX2_WDT_WCR_WDE;
158 }
159 
160 static int imx2_wdt_ping(struct watchdog_device *wdog)
161 {
162 	struct imx2_wdt_device *wdev = watchdog_get_drvdata(wdog);
163 
164 	regmap_write(wdev->regmap, IMX2_WDT_WSR, IMX2_WDT_SEQ1);
165 	regmap_write(wdev->regmap, IMX2_WDT_WSR, IMX2_WDT_SEQ2);
166 	return 0;
167 }
168 
169 static void __imx2_wdt_set_timeout(struct watchdog_device *wdog,
170 				   unsigned int new_timeout)
171 {
172 	struct imx2_wdt_device *wdev = watchdog_get_drvdata(wdog);
173 
174 	regmap_update_bits(wdev->regmap, IMX2_WDT_WCR, IMX2_WDT_WCR_WT,
175 			   WDOG_SEC_TO_COUNT(new_timeout));
176 }
177 
178 static int imx2_wdt_set_timeout(struct watchdog_device *wdog,
179 				unsigned int new_timeout)
180 {
181 	unsigned int actual;
182 
183 	actual = min(new_timeout, IMX2_WDT_MAX_TIME);
184 	__imx2_wdt_set_timeout(wdog, actual);
185 	wdog->timeout = new_timeout;
186 	return 0;
187 }
188 
189 static int imx2_wdt_set_pretimeout(struct watchdog_device *wdog,
190 				   unsigned int new_pretimeout)
191 {
192 	struct imx2_wdt_device *wdev = watchdog_get_drvdata(wdog);
193 
194 	if (new_pretimeout >= IMX2_WDT_MAX_TIME)
195 		return -EINVAL;
196 
197 	wdog->pretimeout = new_pretimeout;
198 
199 	regmap_update_bits(wdev->regmap, IMX2_WDT_WICR,
200 			   IMX2_WDT_WICR_WIE | IMX2_WDT_WICR_WICT,
201 			   IMX2_WDT_WICR_WIE | (new_pretimeout << 1));
202 	return 0;
203 }
204 
205 static irqreturn_t imx2_wdt_isr(int irq, void *wdog_arg)
206 {
207 	struct watchdog_device *wdog = wdog_arg;
208 	struct imx2_wdt_device *wdev = watchdog_get_drvdata(wdog);
209 
210 	regmap_write_bits(wdev->regmap, IMX2_WDT_WICR,
211 			  IMX2_WDT_WICR_WTIS, IMX2_WDT_WICR_WTIS);
212 
213 	watchdog_notify_pretimeout(wdog);
214 
215 	return IRQ_HANDLED;
216 }
217 
218 static int imx2_wdt_start(struct watchdog_device *wdog)
219 {
220 	struct imx2_wdt_device *wdev = watchdog_get_drvdata(wdog);
221 
222 	if (imx2_wdt_is_running(wdev))
223 		imx2_wdt_set_timeout(wdog, wdog->timeout);
224 	else
225 		imx2_wdt_setup(wdog);
226 
227 	set_bit(WDOG_HW_RUNNING, &wdog->status);
228 
229 	return imx2_wdt_ping(wdog);
230 }
231 
232 static const struct watchdog_ops imx2_wdt_ops = {
233 	.owner = THIS_MODULE,
234 	.start = imx2_wdt_start,
235 	.ping = imx2_wdt_ping,
236 	.set_timeout = imx2_wdt_set_timeout,
237 	.set_pretimeout = imx2_wdt_set_pretimeout,
238 	.restart = imx2_wdt_restart,
239 };
240 
241 static const struct regmap_config imx2_wdt_regmap_config = {
242 	.reg_bits = 16,
243 	.reg_stride = 2,
244 	.val_bits = 16,
245 	.max_register = 0x8,
246 };
247 
248 static int __init imx2_wdt_probe(struct platform_device *pdev)
249 {
250 	struct imx2_wdt_device *wdev;
251 	struct watchdog_device *wdog;
252 	void __iomem *base;
253 	int ret;
254 	u32 val;
255 
256 	wdev = devm_kzalloc(&pdev->dev, sizeof(*wdev), GFP_KERNEL);
257 	if (!wdev)
258 		return -ENOMEM;
259 
260 	base = devm_platform_ioremap_resource(pdev, 0);
261 	if (IS_ERR(base))
262 		return PTR_ERR(base);
263 
264 	wdev->regmap = devm_regmap_init_mmio_clk(&pdev->dev, NULL, base,
265 						 &imx2_wdt_regmap_config);
266 	if (IS_ERR(wdev->regmap)) {
267 		dev_err(&pdev->dev, "regmap init failed\n");
268 		return PTR_ERR(wdev->regmap);
269 	}
270 
271 	wdev->clk = devm_clk_get(&pdev->dev, NULL);
272 	if (IS_ERR(wdev->clk)) {
273 		dev_err(&pdev->dev, "can't get Watchdog clock\n");
274 		return PTR_ERR(wdev->clk);
275 	}
276 
277 	wdog			= &wdev->wdog;
278 	wdog->info		= &imx2_wdt_info;
279 	wdog->ops		= &imx2_wdt_ops;
280 	wdog->min_timeout	= 1;
281 	wdog->timeout		= IMX2_WDT_DEFAULT_TIME;
282 	wdog->max_hw_heartbeat_ms = IMX2_WDT_MAX_TIME * 1000;
283 	wdog->parent		= &pdev->dev;
284 
285 	ret = platform_get_irq(pdev, 0);
286 	if (ret > 0)
287 		if (!devm_request_irq(&pdev->dev, ret, imx2_wdt_isr, 0,
288 				      dev_name(&pdev->dev), wdog))
289 			wdog->info = &imx2_wdt_pretimeout_info;
290 
291 	ret = clk_prepare_enable(wdev->clk);
292 	if (ret)
293 		return ret;
294 
295 	regmap_read(wdev->regmap, IMX2_WDT_WRSR, &val);
296 	wdog->bootstatus = val & IMX2_WDT_WRSR_TOUT ? WDIOF_CARDRESET : 0;
297 
298 	wdev->ext_reset = of_property_read_bool(pdev->dev.of_node,
299 						"fsl,ext-reset-output");
300 	platform_set_drvdata(pdev, wdog);
301 	watchdog_set_drvdata(wdog, wdev);
302 	watchdog_set_nowayout(wdog, nowayout);
303 	watchdog_set_restart_priority(wdog, 128);
304 	watchdog_init_timeout(wdog, timeout, &pdev->dev);
305 
306 	if (imx2_wdt_is_running(wdev)) {
307 		imx2_wdt_set_timeout(wdog, wdog->timeout);
308 		set_bit(WDOG_HW_RUNNING, &wdog->status);
309 	}
310 
311 	/*
312 	 * Disable the watchdog power down counter at boot. Otherwise the power
313 	 * down counter will pull down the #WDOG interrupt line for one clock
314 	 * cycle.
315 	 */
316 	regmap_write(wdev->regmap, IMX2_WDT_WMCR, 0);
317 
318 	ret = watchdog_register_device(wdog);
319 	if (ret)
320 		goto disable_clk;
321 
322 	dev_info(&pdev->dev, "timeout %d sec (nowayout=%d)\n",
323 		 wdog->timeout, nowayout);
324 
325 	return 0;
326 
327 disable_clk:
328 	clk_disable_unprepare(wdev->clk);
329 	return ret;
330 }
331 
332 static int __exit imx2_wdt_remove(struct platform_device *pdev)
333 {
334 	struct watchdog_device *wdog = platform_get_drvdata(pdev);
335 	struct imx2_wdt_device *wdev = watchdog_get_drvdata(wdog);
336 
337 	watchdog_unregister_device(wdog);
338 
339 	if (imx2_wdt_is_running(wdev)) {
340 		imx2_wdt_ping(wdog);
341 		dev_crit(&pdev->dev, "Device removed: Expect reboot!\n");
342 	}
343 	return 0;
344 }
345 
346 static void imx2_wdt_shutdown(struct platform_device *pdev)
347 {
348 	struct watchdog_device *wdog = platform_get_drvdata(pdev);
349 	struct imx2_wdt_device *wdev = watchdog_get_drvdata(wdog);
350 
351 	if (imx2_wdt_is_running(wdev)) {
352 		/*
353 		 * We are running, configure max timeout before reboot
354 		 * will take place.
355 		 */
356 		imx2_wdt_set_timeout(wdog, IMX2_WDT_MAX_TIME);
357 		imx2_wdt_ping(wdog);
358 		dev_crit(&pdev->dev, "Device shutdown: Expect reboot!\n");
359 	}
360 }
361 
362 #ifdef CONFIG_PM_SLEEP
363 /* Disable watchdog if it is active or non-active but still running */
364 static int imx2_wdt_suspend(struct device *dev)
365 {
366 	struct watchdog_device *wdog = dev_get_drvdata(dev);
367 	struct imx2_wdt_device *wdev = watchdog_get_drvdata(wdog);
368 
369 	/* The watchdog IP block is running */
370 	if (imx2_wdt_is_running(wdev)) {
371 		/*
372 		 * Don't update wdog->timeout, we'll restore the current value
373 		 * during resume.
374 		 */
375 		__imx2_wdt_set_timeout(wdog, IMX2_WDT_MAX_TIME);
376 		imx2_wdt_ping(wdog);
377 	}
378 
379 	clk_disable_unprepare(wdev->clk);
380 
381 	return 0;
382 }
383 
384 /* Enable watchdog and configure it if necessary */
385 static int imx2_wdt_resume(struct device *dev)
386 {
387 	struct watchdog_device *wdog = dev_get_drvdata(dev);
388 	struct imx2_wdt_device *wdev = watchdog_get_drvdata(wdog);
389 	int ret;
390 
391 	ret = clk_prepare_enable(wdev->clk);
392 	if (ret)
393 		return ret;
394 
395 	if (watchdog_active(wdog) && !imx2_wdt_is_running(wdev)) {
396 		/*
397 		 * If the watchdog is still active and resumes
398 		 * from deep sleep state, need to restart the
399 		 * watchdog again.
400 		 */
401 		imx2_wdt_setup(wdog);
402 	}
403 	if (imx2_wdt_is_running(wdev)) {
404 		imx2_wdt_set_timeout(wdog, wdog->timeout);
405 		imx2_wdt_ping(wdog);
406 	}
407 
408 	return 0;
409 }
410 #endif
411 
412 static SIMPLE_DEV_PM_OPS(imx2_wdt_pm_ops, imx2_wdt_suspend,
413 			 imx2_wdt_resume);
414 
415 static const struct of_device_id imx2_wdt_dt_ids[] = {
416 	{ .compatible = "fsl,imx21-wdt", },
417 	{ /* sentinel */ }
418 };
419 MODULE_DEVICE_TABLE(of, imx2_wdt_dt_ids);
420 
421 static struct platform_driver imx2_wdt_driver = {
422 	.remove		= __exit_p(imx2_wdt_remove),
423 	.shutdown	= imx2_wdt_shutdown,
424 	.driver		= {
425 		.name	= DRIVER_NAME,
426 		.pm     = &imx2_wdt_pm_ops,
427 		.of_match_table = imx2_wdt_dt_ids,
428 	},
429 };
430 
431 module_platform_driver_probe(imx2_wdt_driver, imx2_wdt_probe);
432 
433 MODULE_AUTHOR("Wolfram Sang");
434 MODULE_DESCRIPTION("Watchdog driver for IMX2 and later");
435 MODULE_LICENSE("GPL v2");
436 MODULE_ALIAS("platform:" DRIVER_NAME);
437