xref: /openbmc/linux/drivers/watchdog/sp805_wdt.c (revision afb46f79) 
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 <viresh.linux@gmail.com>
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/device.h>
15 #include <linux/resource.h>
16 #include <linux/amba/bus.h>
17 #include <linux/bitops.h>
18 #include <linux/clk.h>
19 #include <linux/io.h>
20 #include <linux/ioport.h>
21 #include <linux/kernel.h>
22 #include <linux/math64.h>
23 #include <linux/module.h>
24 #include <linux/moduleparam.h>
25 #include <linux/pm.h>
26 #include <linux/slab.h>
27 #include <linux/spinlock.h>
28 #include <linux/types.h>
29 #include <linux/watchdog.h>
30 
31 /* default timeout in seconds */
32 #define DEFAULT_TIMEOUT		60
33 
34 #define MODULE_NAME		"sp805-wdt"
35 
36 /* watchdog register offsets and masks */
37 #define WDTLOAD			0x000
38 	#define LOAD_MIN	0x00000001
39 	#define LOAD_MAX	0xFFFFFFFF
40 #define WDTVALUE		0x004
41 #define WDTCONTROL		0x008
42 	/* control register masks */
43 	#define	INT_ENABLE	(1 << 0)
44 	#define	RESET_ENABLE	(1 << 1)
45 #define WDTINTCLR		0x00C
46 #define WDTRIS			0x010
47 #define WDTMIS			0x014
48 	#define INT_MASK	(1 << 0)
49 #define WDTLOCK			0xC00
50 	#define	UNLOCK		0x1ACCE551
51 	#define	LOCK		0x00000001
52 
53 /**
54  * struct sp805_wdt: sp805 wdt device structure
55  * @wdd: instance of struct watchdog_device
56  * @lock: spin lock protecting dev structure and io access
57  * @base: base address of wdt
58  * @clk: clock structure of wdt
59  * @adev: amba device structure of wdt
60  * @status: current status of wdt
61  * @load_val: load value to be set for current timeout
62  * @timeout: current programmed timeout
63  */
64 struct sp805_wdt {
65 	struct watchdog_device		wdd;
66 	spinlock_t			lock;
67 	void __iomem			*base;
68 	struct clk			*clk;
69 	struct amba_device		*adev;
70 	unsigned int			load_val;
71 	unsigned int			timeout;
72 };
73 
74 static bool nowayout = WATCHDOG_NOWAYOUT;
75 module_param(nowayout, bool, 0);
76 MODULE_PARM_DESC(nowayout,
77 		"Set to 1 to keep watchdog running after device release");
78 
79 /* This routine finds load value that will reset system in required timout */
80 static int wdt_setload(struct watchdog_device *wdd, unsigned int timeout)
81 {
82 	struct sp805_wdt *wdt = watchdog_get_drvdata(wdd);
83 	u64 load, rate;
84 
85 	rate = clk_get_rate(wdt->clk);
86 
87 	/*
88 	 * sp805 runs counter with given value twice, after the end of first
89 	 * counter it gives an interrupt and then starts counter again. If
90 	 * interrupt already occurred then it resets the system. This is why
91 	 * load is half of what should be required.
92 	 */
93 	load = div_u64(rate, 2) * timeout - 1;
94 
95 	load = (load > LOAD_MAX) ? LOAD_MAX : load;
96 	load = (load < LOAD_MIN) ? LOAD_MIN : load;
97 
98 	spin_lock(&wdt->lock);
99 	wdt->load_val = load;
100 	/* roundup timeout to closest positive integer value */
101 	wdt->timeout = div_u64((load + 1) * 2 + (rate / 2), rate);
102 	spin_unlock(&wdt->lock);
103 
104 	return 0;
105 }
106 
107 /* returns number of seconds left for reset to occur */
108 static unsigned int wdt_timeleft(struct watchdog_device *wdd)
109 {
110 	struct sp805_wdt *wdt = watchdog_get_drvdata(wdd);
111 	u64 load, rate;
112 
113 	rate = clk_get_rate(wdt->clk);
114 
115 	spin_lock(&wdt->lock);
116 	load = readl_relaxed(wdt->base + WDTVALUE);
117 
118 	/*If the interrupt is inactive then time left is WDTValue + WDTLoad. */
119 	if (!(readl_relaxed(wdt->base + WDTRIS) & INT_MASK))
120 		load += wdt->load_val + 1;
121 	spin_unlock(&wdt->lock);
122 
123 	return div_u64(load, rate);
124 }
125 
126 static int wdt_config(struct watchdog_device *wdd, bool ping)
127 {
128 	struct sp805_wdt *wdt = watchdog_get_drvdata(wdd);
129 	int ret;
130 
131 	if (!ping) {
132 
133 		ret = clk_prepare_enable(wdt->clk);
134 		if (ret) {
135 			dev_err(&wdt->adev->dev, "clock enable fail");
136 			return ret;
137 		}
138 	}
139 
140 	spin_lock(&wdt->lock);
141 
142 	writel_relaxed(UNLOCK, wdt->base + WDTLOCK);
143 	writel_relaxed(wdt->load_val, wdt->base + WDTLOAD);
144 
145 	if (!ping) {
146 		writel_relaxed(INT_MASK, wdt->base + WDTINTCLR);
147 		writel_relaxed(INT_ENABLE | RESET_ENABLE, wdt->base +
148 				WDTCONTROL);
149 	}
150 
151 	writel_relaxed(LOCK, wdt->base + WDTLOCK);
152 
153 	/* Flush posted writes. */
154 	readl_relaxed(wdt->base + WDTLOCK);
155 	spin_unlock(&wdt->lock);
156 
157 	return 0;
158 }
159 
160 static int wdt_ping(struct watchdog_device *wdd)
161 {
162 	return wdt_config(wdd, true);
163 }
164 
165 /* enables watchdog timers reset */
166 static int wdt_enable(struct watchdog_device *wdd)
167 {
168 	return wdt_config(wdd, false);
169 }
170 
171 /* disables watchdog timers reset */
172 static int wdt_disable(struct watchdog_device *wdd)
173 {
174 	struct sp805_wdt *wdt = watchdog_get_drvdata(wdd);
175 
176 	spin_lock(&wdt->lock);
177 
178 	writel_relaxed(UNLOCK, wdt->base + WDTLOCK);
179 	writel_relaxed(0, wdt->base + WDTCONTROL);
180 	writel_relaxed(LOCK, wdt->base + WDTLOCK);
181 
182 	/* Flush posted writes. */
183 	readl_relaxed(wdt->base + WDTLOCK);
184 	spin_unlock(&wdt->lock);
185 
186 	clk_disable_unprepare(wdt->clk);
187 
188 	return 0;
189 }
190 
191 static const struct watchdog_info wdt_info = {
192 	.options = WDIOF_MAGICCLOSE | WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING,
193 	.identity = MODULE_NAME,
194 };
195 
196 static const struct watchdog_ops wdt_ops = {
197 	.owner		= THIS_MODULE,
198 	.start		= wdt_enable,
199 	.stop		= wdt_disable,
200 	.ping		= wdt_ping,
201 	.set_timeout	= wdt_setload,
202 	.get_timeleft	= wdt_timeleft,
203 };
204 
205 static int
206 sp805_wdt_probe(struct amba_device *adev, const struct amba_id *id)
207 {
208 	struct sp805_wdt *wdt;
209 	int ret = 0;
210 
211 	wdt = devm_kzalloc(&adev->dev, sizeof(*wdt), GFP_KERNEL);
212 	if (!wdt) {
213 		ret = -ENOMEM;
214 		goto err;
215 	}
216 
217 	wdt->base = devm_ioremap_resource(&adev->dev, &adev->res);
218 	if (IS_ERR(wdt->base))
219 		return PTR_ERR(wdt->base);
220 
221 	wdt->clk = devm_clk_get(&adev->dev, NULL);
222 	if (IS_ERR(wdt->clk)) {
223 		dev_warn(&adev->dev, "Clock not found\n");
224 		ret = PTR_ERR(wdt->clk);
225 		goto err;
226 	}
227 
228 	wdt->adev = adev;
229 	wdt->wdd.info = &wdt_info;
230 	wdt->wdd.ops = &wdt_ops;
231 
232 	spin_lock_init(&wdt->lock);
233 	watchdog_set_nowayout(&wdt->wdd, nowayout);
234 	watchdog_set_drvdata(&wdt->wdd, wdt);
235 	wdt_setload(&wdt->wdd, DEFAULT_TIMEOUT);
236 
237 	ret = watchdog_register_device(&wdt->wdd);
238 	if (ret) {
239 		dev_err(&adev->dev, "watchdog_register_device() failed: %d\n",
240 				ret);
241 		goto err;
242 	}
243 	amba_set_drvdata(adev, wdt);
244 
245 	dev_info(&adev->dev, "registration successful\n");
246 	return 0;
247 
248 err:
249 	dev_err(&adev->dev, "Probe Failed!!!\n");
250 	return ret;
251 }
252 
253 static int sp805_wdt_remove(struct amba_device *adev)
254 {
255 	struct sp805_wdt *wdt = amba_get_drvdata(adev);
256 
257 	watchdog_unregister_device(&wdt->wdd);
258 	watchdog_set_drvdata(&wdt->wdd, NULL);
259 
260 	return 0;
261 }
262 
263 static int __maybe_unused sp805_wdt_suspend(struct device *dev)
264 {
265 	struct sp805_wdt *wdt = dev_get_drvdata(dev);
266 
267 	if (watchdog_active(&wdt->wdd))
268 		return wdt_disable(&wdt->wdd);
269 
270 	return 0;
271 }
272 
273 static int __maybe_unused sp805_wdt_resume(struct device *dev)
274 {
275 	struct sp805_wdt *wdt = dev_get_drvdata(dev);
276 
277 	if (watchdog_active(&wdt->wdd))
278 		return wdt_enable(&wdt->wdd);
279 
280 	return 0;
281 }
282 
283 static SIMPLE_DEV_PM_OPS(sp805_wdt_dev_pm_ops, sp805_wdt_suspend,
284 		sp805_wdt_resume);
285 
286 static struct amba_id sp805_wdt_ids[] = {
287 	{
288 		.id	= 0x00141805,
289 		.mask	= 0x00ffffff,
290 	},
291 	{ 0, 0 },
292 };
293 
294 MODULE_DEVICE_TABLE(amba, sp805_wdt_ids);
295 
296 static struct amba_driver sp805_wdt_driver = {
297 	.drv = {
298 		.name	= MODULE_NAME,
299 		.pm	= &sp805_wdt_dev_pm_ops,
300 	},
301 	.id_table	= sp805_wdt_ids,
302 	.probe		= sp805_wdt_probe,
303 	.remove = sp805_wdt_remove,
304 };
305 
306 module_amba_driver(sp805_wdt_driver);
307 
308 MODULE_AUTHOR("Viresh Kumar <viresh.linux@gmail.com>");
309 MODULE_DESCRIPTION("ARM SP805 Watchdog Driver");
310 MODULE_LICENSE("GPL");
311