xref: /openbmc/linux/drivers/watchdog/sp805_wdt.c (revision e553d2a5) 
1 /*
2  * drivers/char/watchdog/sp805-wdt.c
3  *
4  * Watchdog driver for ARM SP805 watchdog module
5  *
6  * Copyright (C) 2010 ST Microelectronics
7  * Viresh Kumar <vireshk@kernel.org>
8  *
9  * This file is licensed under the terms of the GNU General Public
10  * License version 2 or later. This program is licensed "as is" without any
11  * warranty of any kind, whether express or implied.
12  */
13 
14 #include <linux/acpi.h>
15 #include <linux/device.h>
16 #include <linux/resource.h>
17 #include <linux/amba/bus.h>
18 #include <linux/bitops.h>
19 #include <linux/clk.h>
20 #include <linux/io.h>
21 #include <linux/ioport.h>
22 #include <linux/kernel.h>
23 #include <linux/math64.h>
24 #include <linux/module.h>
25 #include <linux/moduleparam.h>
26 #include <linux/of.h>
27 #include <linux/pm.h>
28 #include <linux/slab.h>
29 #include <linux/spinlock.h>
30 #include <linux/types.h>
31 #include <linux/watchdog.h>
32 
33 /* default timeout in seconds */
34 #define DEFAULT_TIMEOUT		60
35 
36 #define MODULE_NAME		"sp805-wdt"
37 
38 /* watchdog register offsets and masks */
39 #define WDTLOAD			0x000
40 	#define LOAD_MIN	0x00000001
41 	#define LOAD_MAX	0xFFFFFFFF
42 #define WDTVALUE		0x004
43 #define WDTCONTROL		0x008
44 	/* control register masks */
45 	#define	INT_ENABLE	(1 << 0)
46 	#define	RESET_ENABLE	(1 << 1)
47 	#define	ENABLE_MASK	(INT_ENABLE | RESET_ENABLE)
48 #define WDTINTCLR		0x00C
49 #define WDTRIS			0x010
50 #define WDTMIS			0x014
51 	#define INT_MASK	(1 << 0)
52 #define WDTLOCK			0xC00
53 	#define	UNLOCK		0x1ACCE551
54 	#define	LOCK		0x00000001
55 
56 /**
57  * struct sp805_wdt: sp805 wdt device structure
58  * @wdd: instance of struct watchdog_device
59  * @lock: spin lock protecting dev structure and io access
60  * @base: base address of wdt
61  * @clk: clock structure of wdt
62  * @adev: amba device structure of wdt
63  * @status: current status of wdt
64  * @load_val: load value to be set for current timeout
65  */
66 struct sp805_wdt {
67 	struct watchdog_device		wdd;
68 	spinlock_t			lock;
69 	void __iomem			*base;
70 	struct clk			*clk;
71 	u64				rate;
72 	struct amba_device		*adev;
73 	unsigned int			load_val;
74 };
75 
76 static bool nowayout = WATCHDOG_NOWAYOUT;
77 module_param(nowayout, bool, 0);
78 MODULE_PARM_DESC(nowayout,
79 		"Set to 1 to keep watchdog running after device release");
80 
81 /* returns true if wdt is running; otherwise returns false */
82 static bool wdt_is_running(struct watchdog_device *wdd)
83 {
84 	struct sp805_wdt *wdt = watchdog_get_drvdata(wdd);
85 	u32 wdtcontrol = readl_relaxed(wdt->base + WDTCONTROL);
86 
87 	return (wdtcontrol & ENABLE_MASK) == ENABLE_MASK;
88 }
89 
90 /* This routine finds load value that will reset system in required timout */
91 static int wdt_setload(struct watchdog_device *wdd, unsigned int timeout)
92 {
93 	struct sp805_wdt *wdt = watchdog_get_drvdata(wdd);
94 	u64 load, rate;
95 
96 	rate = wdt->rate;
97 
98 	/*
99 	 * sp805 runs counter with given value twice, after the end of first
100 	 * counter it gives an interrupt and then starts counter again. If
101 	 * interrupt already occurred then it resets the system. This is why
102 	 * load is half of what should be required.
103 	 */
104 	load = div_u64(rate, 2) * timeout - 1;
105 
106 	load = (load > LOAD_MAX) ? LOAD_MAX : load;
107 	load = (load < LOAD_MIN) ? LOAD_MIN : load;
108 
109 	spin_lock(&wdt->lock);
110 	wdt->load_val = load;
111 	/* roundup timeout to closest positive integer value */
112 	wdd->timeout = div_u64((load + 1) * 2 + (rate / 2), rate);
113 	spin_unlock(&wdt->lock);
114 
115 	return 0;
116 }
117 
118 /* returns number of seconds left for reset to occur */
119 static unsigned int wdt_timeleft(struct watchdog_device *wdd)
120 {
121 	struct sp805_wdt *wdt = watchdog_get_drvdata(wdd);
122 	u64 load;
123 
124 	spin_lock(&wdt->lock);
125 	load = readl_relaxed(wdt->base + WDTVALUE);
126 
127 	/*If the interrupt is inactive then time left is WDTValue + WDTLoad. */
128 	if (!(readl_relaxed(wdt->base + WDTRIS) & INT_MASK))
129 		load += wdt->load_val + 1;
130 	spin_unlock(&wdt->lock);
131 
132 	return div_u64(load, wdt->rate);
133 }
134 
135 static int
136 wdt_restart(struct watchdog_device *wdd, unsigned long mode, void *cmd)
137 {
138 	struct sp805_wdt *wdt = watchdog_get_drvdata(wdd);
139 
140 	writel_relaxed(0, wdt->base + WDTCONTROL);
141 	writel_relaxed(0, wdt->base + WDTLOAD);
142 	writel_relaxed(INT_ENABLE | RESET_ENABLE, wdt->base + WDTCONTROL);
143 
144 	return 0;
145 }
146 
147 static int wdt_config(struct watchdog_device *wdd, bool ping)
148 {
149 	struct sp805_wdt *wdt = watchdog_get_drvdata(wdd);
150 	int ret;
151 
152 	if (!ping) {
153 
154 		ret = clk_prepare_enable(wdt->clk);
155 		if (ret) {
156 			dev_err(&wdt->adev->dev, "clock enable fail");
157 			return ret;
158 		}
159 	}
160 
161 	spin_lock(&wdt->lock);
162 
163 	writel_relaxed(UNLOCK, wdt->base + WDTLOCK);
164 	writel_relaxed(wdt->load_val, wdt->base + WDTLOAD);
165 	writel_relaxed(INT_MASK, wdt->base + WDTINTCLR);
166 
167 	if (!ping)
168 		writel_relaxed(INT_ENABLE | RESET_ENABLE, wdt->base +
169 				WDTCONTROL);
170 
171 	writel_relaxed(LOCK, wdt->base + WDTLOCK);
172 
173 	/* Flush posted writes. */
174 	readl_relaxed(wdt->base + WDTLOCK);
175 	spin_unlock(&wdt->lock);
176 
177 	return 0;
178 }
179 
180 static int wdt_ping(struct watchdog_device *wdd)
181 {
182 	return wdt_config(wdd, true);
183 }
184 
185 /* enables watchdog timers reset */
186 static int wdt_enable(struct watchdog_device *wdd)
187 {
188 	return wdt_config(wdd, false);
189 }
190 
191 /* disables watchdog timers reset */
192 static int wdt_disable(struct watchdog_device *wdd)
193 {
194 	struct sp805_wdt *wdt = watchdog_get_drvdata(wdd);
195 
196 	spin_lock(&wdt->lock);
197 
198 	writel_relaxed(UNLOCK, wdt->base + WDTLOCK);
199 	writel_relaxed(0, wdt->base + WDTCONTROL);
200 	writel_relaxed(LOCK, wdt->base + WDTLOCK);
201 
202 	/* Flush posted writes. */
203 	readl_relaxed(wdt->base + WDTLOCK);
204 	spin_unlock(&wdt->lock);
205 
206 	clk_disable_unprepare(wdt->clk);
207 
208 	return 0;
209 }
210 
211 static const struct watchdog_info wdt_info = {
212 	.options = WDIOF_MAGICCLOSE | WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING,
213 	.identity = MODULE_NAME,
214 };
215 
216 static const struct watchdog_ops wdt_ops = {
217 	.owner		= THIS_MODULE,
218 	.start		= wdt_enable,
219 	.stop		= wdt_disable,
220 	.ping		= wdt_ping,
221 	.set_timeout	= wdt_setload,
222 	.get_timeleft	= wdt_timeleft,
223 	.restart	= wdt_restart,
224 };
225 
226 static int
227 sp805_wdt_probe(struct amba_device *adev, const struct amba_id *id)
228 {
229 	struct sp805_wdt *wdt;
230 	int ret = 0;
231 
232 	wdt = devm_kzalloc(&adev->dev, sizeof(*wdt), GFP_KERNEL);
233 	if (!wdt) {
234 		ret = -ENOMEM;
235 		goto err;
236 	}
237 
238 	wdt->base = devm_ioremap_resource(&adev->dev, &adev->res);
239 	if (IS_ERR(wdt->base))
240 		return PTR_ERR(wdt->base);
241 
242 	if (adev->dev.of_node) {
243 		wdt->clk = devm_clk_get(&adev->dev, NULL);
244 		if (IS_ERR(wdt->clk)) {
245 			dev_err(&adev->dev, "Clock not found\n");
246 			return PTR_ERR(wdt->clk);
247 		}
248 		wdt->rate = clk_get_rate(wdt->clk);
249 	} else if (has_acpi_companion(&adev->dev)) {
250 		/*
251 		 * When Driver probe with ACPI device, clock devices
252 		 * are not available, so watchdog rate get from
253 		 * clock-frequency property given in _DSD object.
254 		 */
255 		device_property_read_u64(&adev->dev, "clock-frequency",
256 					 &wdt->rate);
257 		if (!wdt->rate) {
258 			dev_err(&adev->dev, "no clock-frequency property\n");
259 			return -ENODEV;
260 		}
261 	}
262 
263 	wdt->adev = adev;
264 	wdt->wdd.info = &wdt_info;
265 	wdt->wdd.ops = &wdt_ops;
266 	wdt->wdd.parent = &adev->dev;
267 
268 	spin_lock_init(&wdt->lock);
269 	watchdog_set_nowayout(&wdt->wdd, nowayout);
270 	watchdog_set_drvdata(&wdt->wdd, wdt);
271 	watchdog_set_restart_priority(&wdt->wdd, 128);
272 
273 	/*
274 	 * If 'timeout-sec' devicetree property is specified, use that.
275 	 * Otherwise, use DEFAULT_TIMEOUT
276 	 */
277 	wdt->wdd.timeout = DEFAULT_TIMEOUT;
278 	watchdog_init_timeout(&wdt->wdd, 0, &adev->dev);
279 	wdt_setload(&wdt->wdd, wdt->wdd.timeout);
280 
281 	/*
282 	 * If HW is already running, enable/reset the wdt and set the running
283 	 * bit to tell the wdt subsystem
284 	 */
285 	if (wdt_is_running(&wdt->wdd)) {
286 		wdt_enable(&wdt->wdd);
287 		set_bit(WDOG_HW_RUNNING, &wdt->wdd.status);
288 	}
289 
290 	ret = watchdog_register_device(&wdt->wdd);
291 	if (ret)
292 		goto err;
293 	amba_set_drvdata(adev, wdt);
294 
295 	dev_info(&adev->dev, "registration successful\n");
296 	return 0;
297 
298 err:
299 	dev_err(&adev->dev, "Probe Failed!!!\n");
300 	return ret;
301 }
302 
303 static int sp805_wdt_remove(struct amba_device *adev)
304 {
305 	struct sp805_wdt *wdt = amba_get_drvdata(adev);
306 
307 	watchdog_unregister_device(&wdt->wdd);
308 	watchdog_set_drvdata(&wdt->wdd, NULL);
309 
310 	return 0;
311 }
312 
313 static int __maybe_unused sp805_wdt_suspend(struct device *dev)
314 {
315 	struct sp805_wdt *wdt = dev_get_drvdata(dev);
316 
317 	if (watchdog_active(&wdt->wdd))
318 		return wdt_disable(&wdt->wdd);
319 
320 	return 0;
321 }
322 
323 static int __maybe_unused sp805_wdt_resume(struct device *dev)
324 {
325 	struct sp805_wdt *wdt = dev_get_drvdata(dev);
326 
327 	if (watchdog_active(&wdt->wdd))
328 		return wdt_enable(&wdt->wdd);
329 
330 	return 0;
331 }
332 
333 static SIMPLE_DEV_PM_OPS(sp805_wdt_dev_pm_ops, sp805_wdt_suspend,
334 		sp805_wdt_resume);
335 
336 static const struct amba_id sp805_wdt_ids[] = {
337 	{
338 		.id	= 0x00141805,
339 		.mask	= 0x00ffffff,
340 	},
341 	{ 0, 0 },
342 };
343 
344 MODULE_DEVICE_TABLE(amba, sp805_wdt_ids);
345 
346 static struct amba_driver sp805_wdt_driver = {
347 	.drv = {
348 		.name	= MODULE_NAME,
349 		.pm	= &sp805_wdt_dev_pm_ops,
350 	},
351 	.id_table	= sp805_wdt_ids,
352 	.probe		= sp805_wdt_probe,
353 	.remove = sp805_wdt_remove,
354 };
355 
356 module_amba_driver(sp805_wdt_driver);
357 
358 MODULE_AUTHOR("Viresh Kumar <vireshk@kernel.org>");
359 MODULE_DESCRIPTION("ARM SP805 Watchdog Driver");
360 MODULE_LICENSE("GPL");
361