xref: /openbmc/linux/drivers/watchdog/sp805_wdt.c (revision 37002bc6) 
1 // SPDX-License-Identifier: GPL-2.0+
2 /*
3  * drivers/char/watchdog/sp805-wdt.c
4  *
5  * Watchdog driver for ARM SP805 watchdog module
6  *
7  * Copyright (C) 2010 ST Microelectronics
8  * Viresh Kumar <vireshk@kernel.org>
9  *
10  * This file is licensed under the terms of the GNU General Public
11  * License version 2 or later. This program is licensed "as is" without any
12  * warranty of any kind, whether express or implied.
13  */
14 
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/pm.h>
27 #include <linux/property.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: (optional) clock structure of wdt
62  * @rate: (optional) clock rate when provided via properties
63  * @adev: amba device structure of wdt
64  * @status: current status of wdt
65  * @load_val: load value to be set for current timeout
66  */
67 struct sp805_wdt {
68 	struct watchdog_device		wdd;
69 	spinlock_t			lock;
70 	void __iomem			*base;
71 	struct clk			*clk;
72 	u64				rate;
73 	struct amba_device		*adev;
74 	unsigned int			load_val;
75 };
76 
77 static bool nowayout = WATCHDOG_NOWAYOUT;
78 module_param(nowayout, bool, 0);
79 MODULE_PARM_DESC(nowayout,
80 		"Set to 1 to keep watchdog running after device release");
81 
82 /* returns true if wdt is running; otherwise returns false */
83 static bool wdt_is_running(struct watchdog_device *wdd)
84 {
85 	struct sp805_wdt *wdt = watchdog_get_drvdata(wdd);
86 	u32 wdtcontrol = readl_relaxed(wdt->base + WDTCONTROL);
87 
88 	return (wdtcontrol & ENABLE_MASK) == ENABLE_MASK;
89 }
90 
91 /* This routine finds load value that will reset system in required timeout */
92 static int wdt_setload(struct watchdog_device *wdd, unsigned int timeout)
93 {
94 	struct sp805_wdt *wdt = watchdog_get_drvdata(wdd);
95 	u64 load, rate;
96 
97 	rate = wdt->rate;
98 
99 	/*
100 	 * sp805 runs counter with given value twice, after the end of first
101 	 * counter it gives an interrupt and then starts counter again. If
102 	 * interrupt already occurred then it resets the system. This is why
103 	 * load is half of what should be required.
104 	 */
105 	load = div_u64(rate, 2) * timeout - 1;
106 
107 	load = (load > LOAD_MAX) ? LOAD_MAX : load;
108 	load = (load < LOAD_MIN) ? LOAD_MIN : load;
109 
110 	spin_lock(&wdt->lock);
111 	wdt->load_val = load;
112 	/* roundup timeout to closest positive integer value */
113 	wdd->timeout = div_u64((load + 1) * 2 + (rate / 2), rate);
114 	spin_unlock(&wdt->lock);
115 
116 	return 0;
117 }
118 
119 /* returns number of seconds left for reset to occur */
120 static unsigned int wdt_timeleft(struct watchdog_device *wdd)
121 {
122 	struct sp805_wdt *wdt = watchdog_get_drvdata(wdd);
123 	u64 load;
124 
125 	spin_lock(&wdt->lock);
126 	load = readl_relaxed(wdt->base + WDTVALUE);
127 
128 	/*If the interrupt is inactive then time left is WDTValue + WDTLoad. */
129 	if (!(readl_relaxed(wdt->base + WDTRIS) & INT_MASK))
130 		load += wdt->load_val + 1;
131 	spin_unlock(&wdt->lock);
132 
133 	return div_u64(load, wdt->rate);
134 }
135 
136 static int
137 wdt_restart(struct watchdog_device *wdd, unsigned long mode, void *cmd)
138 {
139 	struct sp805_wdt *wdt = watchdog_get_drvdata(wdd);
140 
141 	writel_relaxed(UNLOCK, wdt->base + WDTLOCK);
142 	writel_relaxed(0, wdt->base + WDTCONTROL);
143 	writel_relaxed(0, wdt->base + WDTLOAD);
144 	writel_relaxed(INT_ENABLE | RESET_ENABLE, wdt->base + WDTCONTROL);
145 
146 	/* Flush posted writes. */
147 	readl_relaxed(wdt->base + WDTLOCK);
148 
149 	return 0;
150 }
151 
152 static int wdt_config(struct watchdog_device *wdd, bool ping)
153 {
154 	struct sp805_wdt *wdt = watchdog_get_drvdata(wdd);
155 	int ret;
156 
157 	if (!ping) {
158 
159 		ret = clk_prepare_enable(wdt->clk);
160 		if (ret) {
161 			dev_err(&wdt->adev->dev, "clock enable fail");
162 			return ret;
163 		}
164 	}
165 
166 	spin_lock(&wdt->lock);
167 
168 	writel_relaxed(UNLOCK, wdt->base + WDTLOCK);
169 	writel_relaxed(wdt->load_val, wdt->base + WDTLOAD);
170 	writel_relaxed(INT_MASK, wdt->base + WDTINTCLR);
171 
172 	if (!ping)
173 		writel_relaxed(INT_ENABLE | RESET_ENABLE, wdt->base +
174 				WDTCONTROL);
175 
176 	writel_relaxed(LOCK, wdt->base + WDTLOCK);
177 
178 	/* Flush posted writes. */
179 	readl_relaxed(wdt->base + WDTLOCK);
180 	spin_unlock(&wdt->lock);
181 
182 	return 0;
183 }
184 
185 static int wdt_ping(struct watchdog_device *wdd)
186 {
187 	return wdt_config(wdd, true);
188 }
189 
190 /* enables watchdog timers reset */
191 static int wdt_enable(struct watchdog_device *wdd)
192 {
193 	return wdt_config(wdd, false);
194 }
195 
196 /* disables watchdog timers reset */
197 static int wdt_disable(struct watchdog_device *wdd)
198 {
199 	struct sp805_wdt *wdt = watchdog_get_drvdata(wdd);
200 
201 	spin_lock(&wdt->lock);
202 
203 	writel_relaxed(UNLOCK, wdt->base + WDTLOCK);
204 	writel_relaxed(0, wdt->base + WDTCONTROL);
205 	writel_relaxed(LOCK, wdt->base + WDTLOCK);
206 
207 	/* Flush posted writes. */
208 	readl_relaxed(wdt->base + WDTLOCK);
209 	spin_unlock(&wdt->lock);
210 
211 	clk_disable_unprepare(wdt->clk);
212 
213 	return 0;
214 }
215 
216 static const struct watchdog_info wdt_info = {
217 	.options = WDIOF_MAGICCLOSE | WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING,
218 	.identity = MODULE_NAME,
219 };
220 
221 static const struct watchdog_ops wdt_ops = {
222 	.owner		= THIS_MODULE,
223 	.start		= wdt_enable,
224 	.stop		= wdt_disable,
225 	.ping		= wdt_ping,
226 	.set_timeout	= wdt_setload,
227 	.get_timeleft	= wdt_timeleft,
228 	.restart	= wdt_restart,
229 };
230 
231 static int
232 sp805_wdt_probe(struct amba_device *adev, const struct amba_id *id)
233 {
234 	struct sp805_wdt *wdt;
235 	u64 rate = 0;
236 	int ret = 0;
237 
238 	wdt = devm_kzalloc(&adev->dev, sizeof(*wdt), GFP_KERNEL);
239 	if (!wdt) {
240 		ret = -ENOMEM;
241 		goto err;
242 	}
243 
244 	wdt->base = devm_ioremap_resource(&adev->dev, &adev->res);
245 	if (IS_ERR(wdt->base))
246 		return PTR_ERR(wdt->base);
247 
248 	/*
249 	 * When driver probe with ACPI device, clock devices
250 	 * are not available, so watchdog rate get from
251 	 * clock-frequency property given in _DSD object.
252 	 */
253 	device_property_read_u64(&adev->dev, "clock-frequency", &rate);
254 
255 	wdt->clk = devm_clk_get_optional(&adev->dev, NULL);
256 	if (IS_ERR(wdt->clk))
257 		return dev_err_probe(&adev->dev, PTR_ERR(wdt->clk), "Clock not found\n");
258 
259 	wdt->rate = clk_get_rate(wdt->clk);
260 	if (!wdt->rate)
261 		wdt->rate = rate;
262 	if (!wdt->rate) {
263 		dev_err(&adev->dev, "no clock-frequency property\n");
264 		return -ENODEV;
265 	}
266 
267 	wdt->adev = adev;
268 	wdt->wdd.info = &wdt_info;
269 	wdt->wdd.ops = &wdt_ops;
270 	wdt->wdd.parent = &adev->dev;
271 
272 	spin_lock_init(&wdt->lock);
273 	watchdog_set_nowayout(&wdt->wdd, nowayout);
274 	watchdog_set_drvdata(&wdt->wdd, wdt);
275 	watchdog_set_restart_priority(&wdt->wdd, 128);
276 	watchdog_stop_on_unregister(&wdt->wdd);
277 
278 	/*
279 	 * If 'timeout-sec' devicetree property is specified, use that.
280 	 * Otherwise, use DEFAULT_TIMEOUT
281 	 */
282 	wdt->wdd.timeout = DEFAULT_TIMEOUT;
283 	watchdog_init_timeout(&wdt->wdd, 0, &adev->dev);
284 	wdt_setload(&wdt->wdd, wdt->wdd.timeout);
285 
286 	/*
287 	 * If HW is already running, enable/reset the wdt and set the running
288 	 * bit to tell the wdt subsystem
289 	 */
290 	if (wdt_is_running(&wdt->wdd)) {
291 		wdt_enable(&wdt->wdd);
292 		set_bit(WDOG_HW_RUNNING, &wdt->wdd.status);
293 	}
294 
295 	watchdog_stop_on_reboot(&wdt->wdd);
296 	ret = watchdog_register_device(&wdt->wdd);
297 	if (ret)
298 		goto err;
299 	amba_set_drvdata(adev, wdt);
300 
301 	dev_info(&adev->dev, "registration successful\n");
302 	return 0;
303 
304 err:
305 	dev_err(&adev->dev, "Probe Failed!!!\n");
306 	return ret;
307 }
308 
309 static void sp805_wdt_remove(struct amba_device *adev)
310 {
311 	struct sp805_wdt *wdt = amba_get_drvdata(adev);
312 
313 	watchdog_unregister_device(&wdt->wdd);
314 	watchdog_set_drvdata(&wdt->wdd, NULL);
315 }
316 
317 static int __maybe_unused sp805_wdt_suspend(struct device *dev)
318 {
319 	struct sp805_wdt *wdt = dev_get_drvdata(dev);
320 
321 	if (watchdog_active(&wdt->wdd))
322 		return wdt_disable(&wdt->wdd);
323 
324 	return 0;
325 }
326 
327 static int __maybe_unused sp805_wdt_resume(struct device *dev)
328 {
329 	struct sp805_wdt *wdt = dev_get_drvdata(dev);
330 
331 	if (watchdog_active(&wdt->wdd))
332 		return wdt_enable(&wdt->wdd);
333 
334 	return 0;
335 }
336 
337 static SIMPLE_DEV_PM_OPS(sp805_wdt_dev_pm_ops, sp805_wdt_suspend,
338 		sp805_wdt_resume);
339 
340 static const struct amba_id sp805_wdt_ids[] = {
341 	{
342 		.id	= 0x00141805,
343 		.mask	= 0x00ffffff,
344 	},
345 	{
346 		.id     = 0x001bb824,
347 		.mask   = 0x00ffffff,
348 	},
349 	{ 0, 0 },
350 };
351 
352 MODULE_DEVICE_TABLE(amba, sp805_wdt_ids);
353 
354 static struct amba_driver sp805_wdt_driver = {
355 	.drv = {
356 		.name	= MODULE_NAME,
357 		.pm	= &sp805_wdt_dev_pm_ops,
358 	},
359 	.id_table	= sp805_wdt_ids,
360 	.probe		= sp805_wdt_probe,
361 	.remove = sp805_wdt_remove,
362 };
363 
364 module_amba_driver(sp805_wdt_driver);
365 
366 MODULE_AUTHOR("Viresh Kumar <vireshk@kernel.org>");
367 MODULE_DESCRIPTION("ARM SP805 Watchdog Driver");
368 MODULE_LICENSE("GPL");
369