1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * Copyright 2019 NXP.
4  */
5 
6 #include <linux/clk.h>
7 #include <linux/io.h>
8 #include <linux/iopoll.h>
9 #include <linux/kernel.h>
10 #include <linux/module.h>
11 #include <linux/of.h>
12 #include <linux/platform_device.h>
13 #include <linux/reboot.h>
14 #include <linux/watchdog.h>
15 
16 #define WDOG_CS			0x0
17 #define WDOG_CS_FLG		BIT(14)
18 #define WDOG_CS_CMD32EN		BIT(13)
19 #define WDOG_CS_PRES		BIT(12)
20 #define WDOG_CS_ULK		BIT(11)
21 #define WDOG_CS_RCS		BIT(10)
22 #define LPO_CLK			0x1
23 #define LPO_CLK_SHIFT		8
24 #define WDOG_CS_CLK		(LPO_CLK << LPO_CLK_SHIFT)
25 #define WDOG_CS_EN		BIT(7)
26 #define WDOG_CS_UPDATE		BIT(5)
27 #define WDOG_CS_WAIT		BIT(1)
28 #define WDOG_CS_STOP		BIT(0)
29 
30 #define WDOG_CNT	0x4
31 #define WDOG_TOVAL	0x8
32 
33 #define REFRESH_SEQ0	0xA602
34 #define REFRESH_SEQ1	0xB480
35 #define REFRESH		((REFRESH_SEQ1 << 16) | REFRESH_SEQ0)
36 
37 #define UNLOCK_SEQ0	0xC520
38 #define UNLOCK_SEQ1	0xD928
39 #define UNLOCK		((UNLOCK_SEQ1 << 16) | UNLOCK_SEQ0)
40 
41 #define DEFAULT_TIMEOUT	60
42 #define MAX_TIMEOUT	128
43 #define WDOG_CLOCK_RATE	1000
44 #define WDOG_ULK_WAIT_TIMEOUT	1000
45 #define WDOG_RCS_WAIT_TIMEOUT	10000
46 #define WDOG_RCS_POST_WAIT 3000
47 
48 #define RETRY_MAX 5
49 
50 static bool nowayout = WATCHDOG_NOWAYOUT;
51 module_param(nowayout, bool, 0000);
52 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
53 		 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
54 
55 struct imx_wdt_hw_feature {
56 	bool prescaler_enable;
57 	u32 wdog_clock_rate;
58 };
59 
60 struct imx7ulp_wdt_device {
61 	struct watchdog_device wdd;
62 	void __iomem *base;
63 	struct clk *clk;
64 	bool post_rcs_wait;
65 	const struct imx_wdt_hw_feature *hw;
66 };
67 
imx7ulp_wdt_wait_ulk(void __iomem * base)68 static int imx7ulp_wdt_wait_ulk(void __iomem *base)
69 {
70 	u32 val = readl(base + WDOG_CS);
71 
72 	if (!(val & WDOG_CS_ULK) &&
73 	    readl_poll_timeout_atomic(base + WDOG_CS, val,
74 				      val & WDOG_CS_ULK, 0,
75 				      WDOG_ULK_WAIT_TIMEOUT))
76 		return -ETIMEDOUT;
77 
78 	return 0;
79 }
80 
imx7ulp_wdt_wait_rcs(struct imx7ulp_wdt_device * wdt)81 static int imx7ulp_wdt_wait_rcs(struct imx7ulp_wdt_device *wdt)
82 {
83 	int ret = 0;
84 	u32 val = readl(wdt->base + WDOG_CS);
85 	u64 timeout = (val & WDOG_CS_PRES) ?
86 		WDOG_RCS_WAIT_TIMEOUT * 256 : WDOG_RCS_WAIT_TIMEOUT;
87 	unsigned long wait_min = (val & WDOG_CS_PRES) ?
88 		WDOG_RCS_POST_WAIT * 256 : WDOG_RCS_POST_WAIT;
89 
90 	if (!(val & WDOG_CS_RCS) &&
91 	    readl_poll_timeout(wdt->base + WDOG_CS, val, val & WDOG_CS_RCS, 100,
92 			       timeout))
93 		ret = -ETIMEDOUT;
94 
95 	/* Wait 2.5 clocks after RCS done */
96 	if (wdt->post_rcs_wait)
97 		usleep_range(wait_min, wait_min + 2000);
98 
99 	return ret;
100 }
101 
_imx7ulp_wdt_enable(struct imx7ulp_wdt_device * wdt,bool enable)102 static int _imx7ulp_wdt_enable(struct imx7ulp_wdt_device *wdt, bool enable)
103 {
104 	u32 val = readl(wdt->base + WDOG_CS);
105 	int ret;
106 
107 	local_irq_disable();
108 	writel(UNLOCK, wdt->base + WDOG_CNT);
109 	ret = imx7ulp_wdt_wait_ulk(wdt->base);
110 	if (ret)
111 		goto enable_out;
112 	if (enable)
113 		writel(val | WDOG_CS_EN, wdt->base + WDOG_CS);
114 	else
115 		writel(val & ~WDOG_CS_EN, wdt->base + WDOG_CS);
116 
117 	local_irq_enable();
118 	ret = imx7ulp_wdt_wait_rcs(wdt);
119 
120 	return ret;
121 
122 enable_out:
123 	local_irq_enable();
124 	return ret;
125 }
126 
imx7ulp_wdt_enable(struct watchdog_device * wdog,bool enable)127 static int imx7ulp_wdt_enable(struct watchdog_device *wdog, bool enable)
128 {
129 	struct imx7ulp_wdt_device *wdt = watchdog_get_drvdata(wdog);
130 	int ret;
131 	u32 val;
132 	u32 loop = RETRY_MAX;
133 
134 	do {
135 		ret = _imx7ulp_wdt_enable(wdt, enable);
136 		val = readl(wdt->base + WDOG_CS);
137 	} while (--loop > 0 && ((!!(val & WDOG_CS_EN)) != enable || ret));
138 
139 	if (loop == 0)
140 		return -EBUSY;
141 
142 	return ret;
143 }
144 
imx7ulp_wdt_ping(struct watchdog_device * wdog)145 static int imx7ulp_wdt_ping(struct watchdog_device *wdog)
146 {
147 	struct imx7ulp_wdt_device *wdt = watchdog_get_drvdata(wdog);
148 
149 	writel(REFRESH, wdt->base + WDOG_CNT);
150 
151 	return 0;
152 }
153 
imx7ulp_wdt_start(struct watchdog_device * wdog)154 static int imx7ulp_wdt_start(struct watchdog_device *wdog)
155 {
156 	return imx7ulp_wdt_enable(wdog, true);
157 }
158 
imx7ulp_wdt_stop(struct watchdog_device * wdog)159 static int imx7ulp_wdt_stop(struct watchdog_device *wdog)
160 {
161 	return imx7ulp_wdt_enable(wdog, false);
162 }
163 
_imx7ulp_wdt_set_timeout(struct imx7ulp_wdt_device * wdt,unsigned int toval)164 static int _imx7ulp_wdt_set_timeout(struct imx7ulp_wdt_device *wdt,
165 				   unsigned int toval)
166 {
167 	int ret;
168 
169 	local_irq_disable();
170 	writel(UNLOCK, wdt->base + WDOG_CNT);
171 	ret = imx7ulp_wdt_wait_ulk(wdt->base);
172 	if (ret)
173 		goto timeout_out;
174 	writel(toval, wdt->base + WDOG_TOVAL);
175 	local_irq_enable();
176 	ret = imx7ulp_wdt_wait_rcs(wdt);
177 	return ret;
178 
179 timeout_out:
180 	local_irq_enable();
181 	return ret;
182 }
183 
imx7ulp_wdt_set_timeout(struct watchdog_device * wdog,unsigned int timeout)184 static int imx7ulp_wdt_set_timeout(struct watchdog_device *wdog,
185 				   unsigned int timeout)
186 {
187 	struct imx7ulp_wdt_device *wdt = watchdog_get_drvdata(wdog);
188 	u32 toval = wdt->hw->wdog_clock_rate * timeout;
189 	u32 val;
190 	int ret;
191 	u32 loop = RETRY_MAX;
192 
193 	do {
194 		ret = _imx7ulp_wdt_set_timeout(wdt, toval);
195 		val = readl(wdt->base + WDOG_TOVAL);
196 	} while (--loop > 0 && (val != toval || ret));
197 
198 	if (loop == 0)
199 		return -EBUSY;
200 
201 	wdog->timeout = timeout;
202 	return ret;
203 }
204 
imx7ulp_wdt_restart(struct watchdog_device * wdog,unsigned long action,void * data)205 static int imx7ulp_wdt_restart(struct watchdog_device *wdog,
206 			       unsigned long action, void *data)
207 {
208 	struct imx7ulp_wdt_device *wdt = watchdog_get_drvdata(wdog);
209 	int ret;
210 
211 	ret = imx7ulp_wdt_enable(wdog, true);
212 	if (ret)
213 		return ret;
214 
215 	ret = imx7ulp_wdt_set_timeout(&wdt->wdd, 1);
216 	if (ret)
217 		return ret;
218 
219 	/* wait for wdog to fire */
220 	while (true)
221 		;
222 
223 	return NOTIFY_DONE;
224 }
225 
226 static const struct watchdog_ops imx7ulp_wdt_ops = {
227 	.owner = THIS_MODULE,
228 	.start = imx7ulp_wdt_start,
229 	.stop  = imx7ulp_wdt_stop,
230 	.ping  = imx7ulp_wdt_ping,
231 	.set_timeout = imx7ulp_wdt_set_timeout,
232 	.restart = imx7ulp_wdt_restart,
233 };
234 
235 static const struct watchdog_info imx7ulp_wdt_info = {
236 	.identity = "i.MX7ULP watchdog timer",
237 	.options  = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING |
238 		    WDIOF_MAGICCLOSE,
239 };
240 
_imx7ulp_wdt_init(struct imx7ulp_wdt_device * wdt,unsigned int timeout,unsigned int cs)241 static int _imx7ulp_wdt_init(struct imx7ulp_wdt_device *wdt, unsigned int timeout, unsigned int cs)
242 {
243 	u32 val;
244 	int ret;
245 
246 	local_irq_disable();
247 
248 	val = readl(wdt->base + WDOG_CS);
249 	if (val & WDOG_CS_CMD32EN) {
250 		writel(UNLOCK, wdt->base + WDOG_CNT);
251 	} else {
252 		mb();
253 		/* unlock the wdog for reconfiguration */
254 		writel_relaxed(UNLOCK_SEQ0, wdt->base + WDOG_CNT);
255 		writel_relaxed(UNLOCK_SEQ1, wdt->base + WDOG_CNT);
256 		mb();
257 	}
258 
259 	ret = imx7ulp_wdt_wait_ulk(wdt->base);
260 	if (ret)
261 		goto init_out;
262 
263 	/* set an initial timeout value in TOVAL */
264 	writel(timeout, wdt->base + WDOG_TOVAL);
265 	writel(cs, wdt->base + WDOG_CS);
266 	local_irq_enable();
267 	ret = imx7ulp_wdt_wait_rcs(wdt);
268 
269 	return ret;
270 
271 init_out:
272 	local_irq_enable();
273 	return ret;
274 }
275 
imx7ulp_wdt_init(struct imx7ulp_wdt_device * wdt,unsigned int timeout)276 static int imx7ulp_wdt_init(struct imx7ulp_wdt_device *wdt, unsigned int timeout)
277 {
278 	/* enable 32bit command sequence and reconfigure */
279 	u32 val = WDOG_CS_CMD32EN | WDOG_CS_CLK | WDOG_CS_UPDATE |
280 		  WDOG_CS_WAIT | WDOG_CS_STOP;
281 	u32 cs, toval;
282 	int ret;
283 	u32 loop = RETRY_MAX;
284 
285 	if (wdt->hw->prescaler_enable)
286 		val |= WDOG_CS_PRES;
287 
288 	do {
289 		ret = _imx7ulp_wdt_init(wdt, timeout, val);
290 		toval = readl(wdt->base + WDOG_TOVAL);
291 		cs = readl(wdt->base + WDOG_CS);
292 		cs &= ~(WDOG_CS_FLG | WDOG_CS_ULK | WDOG_CS_RCS);
293 	} while (--loop > 0 && (cs != val || toval != timeout || ret));
294 
295 	if (loop == 0)
296 		return -EBUSY;
297 
298 	return ret;
299 }
300 
imx7ulp_wdt_probe(struct platform_device * pdev)301 static int imx7ulp_wdt_probe(struct platform_device *pdev)
302 {
303 	struct imx7ulp_wdt_device *imx7ulp_wdt;
304 	struct device *dev = &pdev->dev;
305 	struct watchdog_device *wdog;
306 	int ret;
307 
308 	imx7ulp_wdt = devm_kzalloc(dev, sizeof(*imx7ulp_wdt), GFP_KERNEL);
309 	if (!imx7ulp_wdt)
310 		return -ENOMEM;
311 
312 	platform_set_drvdata(pdev, imx7ulp_wdt);
313 
314 	imx7ulp_wdt->base = devm_platform_ioremap_resource(pdev, 0);
315 	if (IS_ERR(imx7ulp_wdt->base))
316 		return PTR_ERR(imx7ulp_wdt->base);
317 
318 	imx7ulp_wdt->clk = devm_clk_get_enabled(dev, NULL);
319 	if (IS_ERR(imx7ulp_wdt->clk)) {
320 		dev_err(dev, "Failed to get watchdog clock\n");
321 		return PTR_ERR(imx7ulp_wdt->clk);
322 	}
323 
324 	imx7ulp_wdt->post_rcs_wait = true;
325 	if (of_device_is_compatible(dev->of_node,
326 				    "fsl,imx8ulp-wdt")) {
327 		dev_info(dev, "imx8ulp wdt probe\n");
328 		imx7ulp_wdt->post_rcs_wait = false;
329 	} else {
330 		dev_info(dev, "imx7ulp wdt probe\n");
331 	}
332 
333 	wdog = &imx7ulp_wdt->wdd;
334 	wdog->info = &imx7ulp_wdt_info;
335 	wdog->ops = &imx7ulp_wdt_ops;
336 	wdog->min_timeout = 1;
337 	wdog->max_timeout = MAX_TIMEOUT;
338 	wdog->parent = dev;
339 	wdog->timeout = DEFAULT_TIMEOUT;
340 
341 	watchdog_init_timeout(wdog, 0, dev);
342 	watchdog_stop_on_reboot(wdog);
343 	watchdog_stop_on_unregister(wdog);
344 	watchdog_set_drvdata(wdog, imx7ulp_wdt);
345 
346 	imx7ulp_wdt->hw = of_device_get_match_data(dev);
347 	ret = imx7ulp_wdt_init(imx7ulp_wdt, wdog->timeout * imx7ulp_wdt->hw->wdog_clock_rate);
348 	if (ret)
349 		return ret;
350 
351 	return devm_watchdog_register_device(dev, wdog);
352 }
353 
imx7ulp_wdt_suspend_noirq(struct device * dev)354 static int __maybe_unused imx7ulp_wdt_suspend_noirq(struct device *dev)
355 {
356 	struct imx7ulp_wdt_device *imx7ulp_wdt = dev_get_drvdata(dev);
357 
358 	if (watchdog_active(&imx7ulp_wdt->wdd))
359 		imx7ulp_wdt_stop(&imx7ulp_wdt->wdd);
360 
361 	clk_disable_unprepare(imx7ulp_wdt->clk);
362 
363 	return 0;
364 }
365 
imx7ulp_wdt_resume_noirq(struct device * dev)366 static int __maybe_unused imx7ulp_wdt_resume_noirq(struct device *dev)
367 {
368 	struct imx7ulp_wdt_device *imx7ulp_wdt = dev_get_drvdata(dev);
369 	u32 timeout = imx7ulp_wdt->wdd.timeout * imx7ulp_wdt->hw->wdog_clock_rate;
370 	int ret;
371 
372 	ret = clk_prepare_enable(imx7ulp_wdt->clk);
373 	if (ret)
374 		return ret;
375 
376 	if (watchdog_active(&imx7ulp_wdt->wdd)) {
377 		imx7ulp_wdt_init(imx7ulp_wdt, timeout);
378 		imx7ulp_wdt_start(&imx7ulp_wdt->wdd);
379 		imx7ulp_wdt_ping(&imx7ulp_wdt->wdd);
380 	}
381 
382 	return 0;
383 }
384 
385 static const struct dev_pm_ops imx7ulp_wdt_pm_ops = {
386 	SET_NOIRQ_SYSTEM_SLEEP_PM_OPS(imx7ulp_wdt_suspend_noirq,
387 				      imx7ulp_wdt_resume_noirq)
388 };
389 
390 static const struct imx_wdt_hw_feature imx7ulp_wdt_hw = {
391 	.prescaler_enable = false,
392 	.wdog_clock_rate = 1000,
393 };
394 
395 static const struct imx_wdt_hw_feature imx93_wdt_hw = {
396 	.prescaler_enable = true,
397 	.wdog_clock_rate = 125,
398 };
399 
400 static const struct of_device_id imx7ulp_wdt_dt_ids[] = {
401 	{ .compatible = "fsl,imx8ulp-wdt", .data = &imx7ulp_wdt_hw, },
402 	{ .compatible = "fsl,imx7ulp-wdt", .data = &imx7ulp_wdt_hw, },
403 	{ .compatible = "fsl,imx93-wdt", .data = &imx93_wdt_hw, },
404 	{ /* sentinel */ }
405 };
406 MODULE_DEVICE_TABLE(of, imx7ulp_wdt_dt_ids);
407 
408 static struct platform_driver imx7ulp_wdt_driver = {
409 	.probe		= imx7ulp_wdt_probe,
410 	.driver		= {
411 		.name	= "imx7ulp-wdt",
412 		.pm	= &imx7ulp_wdt_pm_ops,
413 		.of_match_table = imx7ulp_wdt_dt_ids,
414 	},
415 };
416 module_platform_driver(imx7ulp_wdt_driver);
417 
418 MODULE_AUTHOR("Anson Huang <Anson.Huang@nxp.com>");
419 MODULE_DESCRIPTION("Freescale i.MX7ULP watchdog driver");
420 MODULE_LICENSE("GPL v2");
421