xref: /openbmc/linux/drivers/watchdog/sprd_wdt.c (revision 2a6c9c65)
1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * Spreadtrum watchdog driver
4  * Copyright (C) 2017 Spreadtrum - http://www.spreadtrum.com
5  */
6 
7 #include <linux/bitops.h>
8 #include <linux/clk.h>
9 #include <linux/delay.h>
10 #include <linux/device.h>
11 #include <linux/err.h>
12 #include <linux/interrupt.h>
13 #include <linux/io.h>
14 #include <linux/kernel.h>
15 #include <linux/module.h>
16 #include <linux/of.h>
17 #include <linux/of_address.h>
18 #include <linux/platform_device.h>
19 #include <linux/watchdog.h>
20 
21 #define SPRD_WDT_LOAD_LOW		0x0
22 #define SPRD_WDT_LOAD_HIGH		0x4
23 #define SPRD_WDT_CTRL			0x8
24 #define SPRD_WDT_INT_CLR		0xc
25 #define SPRD_WDT_INT_RAW		0x10
26 #define SPRD_WDT_INT_MSK		0x14
27 #define SPRD_WDT_CNT_LOW		0x18
28 #define SPRD_WDT_CNT_HIGH		0x1c
29 #define SPRD_WDT_LOCK			0x20
30 #define SPRD_WDT_IRQ_LOAD_LOW		0x2c
31 #define SPRD_WDT_IRQ_LOAD_HIGH		0x30
32 
33 /* WDT_CTRL */
34 #define SPRD_WDT_INT_EN_BIT		BIT(0)
35 #define SPRD_WDT_CNT_EN_BIT		BIT(1)
36 #define SPRD_WDT_NEW_VER_EN		BIT(2)
37 #define SPRD_WDT_RST_EN_BIT		BIT(3)
38 
39 /* WDT_INT_CLR */
40 #define SPRD_WDT_INT_CLEAR_BIT		BIT(0)
41 #define SPRD_WDT_RST_CLEAR_BIT		BIT(3)
42 
43 /* WDT_INT_RAW */
44 #define SPRD_WDT_INT_RAW_BIT		BIT(0)
45 #define SPRD_WDT_RST_RAW_BIT		BIT(3)
46 #define SPRD_WDT_LD_BUSY_BIT		BIT(4)
47 
48 /* 1s equal to 32768 counter steps */
49 #define SPRD_WDT_CNT_STEP		32768
50 
51 #define SPRD_WDT_UNLOCK_KEY		0xe551
52 #define SPRD_WDT_MIN_TIMEOUT		3
53 #define SPRD_WDT_MAX_TIMEOUT		60
54 
55 #define SPRD_WDT_CNT_HIGH_SHIFT		16
56 #define SPRD_WDT_LOW_VALUE_MASK		GENMASK(15, 0)
57 #define SPRD_WDT_LOAD_TIMEOUT		11
58 
59 struct sprd_wdt {
60 	void __iomem *base;
61 	struct watchdog_device wdd;
62 	struct clk *enable;
63 	struct clk *rtc_enable;
64 	int irq;
65 };
66 
to_sprd_wdt(struct watchdog_device * wdd)67 static inline struct sprd_wdt *to_sprd_wdt(struct watchdog_device *wdd)
68 {
69 	return container_of(wdd, struct sprd_wdt, wdd);
70 }
71 
sprd_wdt_lock(void __iomem * addr)72 static inline void sprd_wdt_lock(void __iomem *addr)
73 {
74 	writel_relaxed(0x0, addr + SPRD_WDT_LOCK);
75 }
76 
sprd_wdt_unlock(void __iomem * addr)77 static inline void sprd_wdt_unlock(void __iomem *addr)
78 {
79 	writel_relaxed(SPRD_WDT_UNLOCK_KEY, addr + SPRD_WDT_LOCK);
80 }
81 
sprd_wdt_isr(int irq,void * dev_id)82 static irqreturn_t sprd_wdt_isr(int irq, void *dev_id)
83 {
84 	struct sprd_wdt *wdt = (struct sprd_wdt *)dev_id;
85 
86 	sprd_wdt_unlock(wdt->base);
87 	writel_relaxed(SPRD_WDT_INT_CLEAR_BIT, wdt->base + SPRD_WDT_INT_CLR);
88 	sprd_wdt_lock(wdt->base);
89 	watchdog_notify_pretimeout(&wdt->wdd);
90 	return IRQ_HANDLED;
91 }
92 
sprd_wdt_get_cnt_value(struct sprd_wdt * wdt)93 static u32 sprd_wdt_get_cnt_value(struct sprd_wdt *wdt)
94 {
95 	u32 val;
96 
97 	val = readl_relaxed(wdt->base + SPRD_WDT_CNT_HIGH) <<
98 		SPRD_WDT_CNT_HIGH_SHIFT;
99 	val |= readl_relaxed(wdt->base + SPRD_WDT_CNT_LOW) &
100 		SPRD_WDT_LOW_VALUE_MASK;
101 
102 	return val;
103 }
104 
sprd_wdt_load_value(struct sprd_wdt * wdt,u32 timeout,u32 pretimeout)105 static int sprd_wdt_load_value(struct sprd_wdt *wdt, u32 timeout,
106 			       u32 pretimeout)
107 {
108 	u32 val, delay_cnt = 0;
109 	u32 tmr_step = timeout * SPRD_WDT_CNT_STEP;
110 	u32 prtmr_step = pretimeout * SPRD_WDT_CNT_STEP;
111 
112 	/*
113 	 * Checking busy bit to make sure the previous loading operation is
114 	 * done. According to the specification, the busy bit would be set
115 	 * after a new loading operation and last 2 or 3 RTC clock
116 	 * cycles (about 60us~92us).
117 	 */
118 	do {
119 		val = readl_relaxed(wdt->base + SPRD_WDT_INT_RAW);
120 		if (!(val & SPRD_WDT_LD_BUSY_BIT))
121 			break;
122 
123 		usleep_range(10, 100);
124 	} while (delay_cnt++ < SPRD_WDT_LOAD_TIMEOUT);
125 
126 	if (delay_cnt >= SPRD_WDT_LOAD_TIMEOUT)
127 		return -EBUSY;
128 
129 	sprd_wdt_unlock(wdt->base);
130 	writel_relaxed((tmr_step >> SPRD_WDT_CNT_HIGH_SHIFT) &
131 		      SPRD_WDT_LOW_VALUE_MASK, wdt->base + SPRD_WDT_LOAD_HIGH);
132 	writel_relaxed((tmr_step & SPRD_WDT_LOW_VALUE_MASK),
133 		       wdt->base + SPRD_WDT_LOAD_LOW);
134 	writel_relaxed((prtmr_step >> SPRD_WDT_CNT_HIGH_SHIFT) &
135 			SPRD_WDT_LOW_VALUE_MASK,
136 		       wdt->base + SPRD_WDT_IRQ_LOAD_HIGH);
137 	writel_relaxed(prtmr_step & SPRD_WDT_LOW_VALUE_MASK,
138 		       wdt->base + SPRD_WDT_IRQ_LOAD_LOW);
139 	sprd_wdt_lock(wdt->base);
140 
141 	return 0;
142 }
143 
sprd_wdt_enable(struct sprd_wdt * wdt)144 static int sprd_wdt_enable(struct sprd_wdt *wdt)
145 {
146 	u32 val;
147 	int ret;
148 
149 	ret = clk_prepare_enable(wdt->enable);
150 	if (ret)
151 		return ret;
152 	ret = clk_prepare_enable(wdt->rtc_enable);
153 	if (ret) {
154 		clk_disable_unprepare(wdt->enable);
155 		return ret;
156 	}
157 
158 	sprd_wdt_unlock(wdt->base);
159 	val = readl_relaxed(wdt->base + SPRD_WDT_CTRL);
160 	val |= SPRD_WDT_NEW_VER_EN;
161 	writel_relaxed(val, wdt->base + SPRD_WDT_CTRL);
162 	sprd_wdt_lock(wdt->base);
163 	return 0;
164 }
165 
sprd_wdt_disable(void * _data)166 static void sprd_wdt_disable(void *_data)
167 {
168 	struct sprd_wdt *wdt = _data;
169 
170 	sprd_wdt_unlock(wdt->base);
171 	writel_relaxed(0x0, wdt->base + SPRD_WDT_CTRL);
172 	sprd_wdt_lock(wdt->base);
173 
174 	clk_disable_unprepare(wdt->rtc_enable);
175 	clk_disable_unprepare(wdt->enable);
176 }
177 
sprd_wdt_start(struct watchdog_device * wdd)178 static int sprd_wdt_start(struct watchdog_device *wdd)
179 {
180 	struct sprd_wdt *wdt = to_sprd_wdt(wdd);
181 	u32 val;
182 	int ret;
183 
184 	ret = sprd_wdt_load_value(wdt, wdd->timeout, wdd->pretimeout);
185 	if (ret)
186 		return ret;
187 
188 	sprd_wdt_unlock(wdt->base);
189 	val = readl_relaxed(wdt->base + SPRD_WDT_CTRL);
190 	val |= SPRD_WDT_CNT_EN_BIT | SPRD_WDT_INT_EN_BIT | SPRD_WDT_RST_EN_BIT;
191 	writel_relaxed(val, wdt->base + SPRD_WDT_CTRL);
192 	sprd_wdt_lock(wdt->base);
193 	set_bit(WDOG_HW_RUNNING, &wdd->status);
194 
195 	return 0;
196 }
197 
sprd_wdt_stop(struct watchdog_device * wdd)198 static int sprd_wdt_stop(struct watchdog_device *wdd)
199 {
200 	struct sprd_wdt *wdt = to_sprd_wdt(wdd);
201 	u32 val;
202 
203 	sprd_wdt_unlock(wdt->base);
204 	val = readl_relaxed(wdt->base + SPRD_WDT_CTRL);
205 	val &= ~(SPRD_WDT_CNT_EN_BIT | SPRD_WDT_RST_EN_BIT |
206 		SPRD_WDT_INT_EN_BIT);
207 	writel_relaxed(val, wdt->base + SPRD_WDT_CTRL);
208 	sprd_wdt_lock(wdt->base);
209 	return 0;
210 }
211 
sprd_wdt_set_timeout(struct watchdog_device * wdd,u32 timeout)212 static int sprd_wdt_set_timeout(struct watchdog_device *wdd,
213 				u32 timeout)
214 {
215 	struct sprd_wdt *wdt = to_sprd_wdt(wdd);
216 
217 	if (timeout == wdd->timeout)
218 		return 0;
219 
220 	wdd->timeout = timeout;
221 
222 	return sprd_wdt_load_value(wdt, timeout, wdd->pretimeout);
223 }
224 
sprd_wdt_set_pretimeout(struct watchdog_device * wdd,u32 new_pretimeout)225 static int sprd_wdt_set_pretimeout(struct watchdog_device *wdd,
226 				   u32 new_pretimeout)
227 {
228 	struct sprd_wdt *wdt = to_sprd_wdt(wdd);
229 
230 	if (new_pretimeout < wdd->min_timeout)
231 		return -EINVAL;
232 
233 	wdd->pretimeout = new_pretimeout;
234 
235 	return sprd_wdt_load_value(wdt, wdd->timeout, new_pretimeout);
236 }
237 
sprd_wdt_get_timeleft(struct watchdog_device * wdd)238 static u32 sprd_wdt_get_timeleft(struct watchdog_device *wdd)
239 {
240 	struct sprd_wdt *wdt = to_sprd_wdt(wdd);
241 	u32 val;
242 
243 	val = sprd_wdt_get_cnt_value(wdt);
244 	return val / SPRD_WDT_CNT_STEP;
245 }
246 
247 static const struct watchdog_ops sprd_wdt_ops = {
248 	.owner = THIS_MODULE,
249 	.start = sprd_wdt_start,
250 	.stop = sprd_wdt_stop,
251 	.set_timeout = sprd_wdt_set_timeout,
252 	.set_pretimeout = sprd_wdt_set_pretimeout,
253 	.get_timeleft = sprd_wdt_get_timeleft,
254 };
255 
256 static const struct watchdog_info sprd_wdt_info = {
257 	.options = WDIOF_SETTIMEOUT |
258 		   WDIOF_PRETIMEOUT |
259 		   WDIOF_MAGICCLOSE |
260 		   WDIOF_KEEPALIVEPING,
261 	.identity = "Spreadtrum Watchdog Timer",
262 };
263 
sprd_wdt_probe(struct platform_device * pdev)264 static int sprd_wdt_probe(struct platform_device *pdev)
265 {
266 	struct device *dev = &pdev->dev;
267 	struct sprd_wdt *wdt;
268 	int ret;
269 
270 	wdt = devm_kzalloc(dev, sizeof(*wdt), GFP_KERNEL);
271 	if (!wdt)
272 		return -ENOMEM;
273 
274 	wdt->base = devm_platform_ioremap_resource(pdev, 0);
275 	if (IS_ERR(wdt->base))
276 		return PTR_ERR(wdt->base);
277 
278 	wdt->enable = devm_clk_get(dev, "enable");
279 	if (IS_ERR(wdt->enable)) {
280 		dev_err(dev, "can't get the enable clock\n");
281 		return PTR_ERR(wdt->enable);
282 	}
283 
284 	wdt->rtc_enable = devm_clk_get(dev, "rtc_enable");
285 	if (IS_ERR(wdt->rtc_enable)) {
286 		dev_err(dev, "can't get the rtc enable clock\n");
287 		return PTR_ERR(wdt->rtc_enable);
288 	}
289 
290 	wdt->irq = platform_get_irq(pdev, 0);
291 	if (wdt->irq < 0)
292 		return wdt->irq;
293 
294 	ret = devm_request_irq(dev, wdt->irq, sprd_wdt_isr, IRQF_NO_SUSPEND,
295 			       "sprd-wdt", (void *)wdt);
296 	if (ret) {
297 		dev_err(dev, "failed to register irq\n");
298 		return ret;
299 	}
300 
301 	wdt->wdd.info = &sprd_wdt_info;
302 	wdt->wdd.ops = &sprd_wdt_ops;
303 	wdt->wdd.parent = dev;
304 	wdt->wdd.min_timeout = SPRD_WDT_MIN_TIMEOUT;
305 	wdt->wdd.max_timeout = SPRD_WDT_MAX_TIMEOUT;
306 	wdt->wdd.timeout = SPRD_WDT_MAX_TIMEOUT;
307 
308 	ret = sprd_wdt_enable(wdt);
309 	if (ret) {
310 		dev_err(dev, "failed to enable wdt\n");
311 		return ret;
312 	}
313 	ret = devm_add_action_or_reset(dev, sprd_wdt_disable, wdt);
314 	if (ret) {
315 		dev_err(dev, "Failed to add wdt disable action\n");
316 		return ret;
317 	}
318 
319 	watchdog_set_nowayout(&wdt->wdd, WATCHDOG_NOWAYOUT);
320 	watchdog_init_timeout(&wdt->wdd, 0, dev);
321 
322 	ret = devm_watchdog_register_device(dev, &wdt->wdd);
323 	if (ret) {
324 		sprd_wdt_disable(wdt);
325 		return ret;
326 	}
327 	platform_set_drvdata(pdev, wdt);
328 
329 	return 0;
330 }
331 
sprd_wdt_pm_suspend(struct device * dev)332 static int __maybe_unused sprd_wdt_pm_suspend(struct device *dev)
333 {
334 	struct sprd_wdt *wdt = dev_get_drvdata(dev);
335 
336 	if (watchdog_active(&wdt->wdd))
337 		sprd_wdt_stop(&wdt->wdd);
338 	sprd_wdt_disable(wdt);
339 
340 	return 0;
341 }
342 
sprd_wdt_pm_resume(struct device * dev)343 static int __maybe_unused sprd_wdt_pm_resume(struct device *dev)
344 {
345 	struct sprd_wdt *wdt = dev_get_drvdata(dev);
346 	int ret;
347 
348 	ret = sprd_wdt_enable(wdt);
349 	if (ret)
350 		return ret;
351 
352 	if (watchdog_active(&wdt->wdd))
353 		ret = sprd_wdt_start(&wdt->wdd);
354 
355 	return ret;
356 }
357 
358 static const struct dev_pm_ops sprd_wdt_pm_ops = {
359 	SET_SYSTEM_SLEEP_PM_OPS(sprd_wdt_pm_suspend,
360 				sprd_wdt_pm_resume)
361 };
362 
363 static const struct of_device_id sprd_wdt_match_table[] = {
364 	{ .compatible = "sprd,sp9860-wdt", },
365 	{},
366 };
367 MODULE_DEVICE_TABLE(of, sprd_wdt_match_table);
368 
369 static struct platform_driver sprd_watchdog_driver = {
370 	.probe	= sprd_wdt_probe,
371 	.driver	= {
372 		.name = "sprd-wdt",
373 		.of_match_table = sprd_wdt_match_table,
374 		.pm = &sprd_wdt_pm_ops,
375 	},
376 };
377 module_platform_driver(sprd_watchdog_driver);
378 
379 MODULE_AUTHOR("Eric Long <eric.long@spreadtrum.com>");
380 MODULE_DESCRIPTION("Spreadtrum Watchdog Timer Controller Driver");
381 MODULE_LICENSE("GPL v2");
382