sp805_wdt.c revision b1f9cd3225ae2e8626fe7503ae7be92240873049 
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/init.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/slab.h>
28#include <linux/spinlock.h>
29#include <linux/types.h>
30#include <linux/watchdog.h>
31
32/* default timeout in seconds */
33#define DEFAULT_TIMEOUT		60
34
35#define MODULE_NAME		"sp805-wdt"
36
37/* watchdog register offsets and masks */
38#define WDTLOAD			0x000
39	#define LOAD_MIN	0x00000001
40	#define LOAD_MAX	0xFFFFFFFF
41#define WDTVALUE		0x004
42#define WDTCONTROL		0x008
43	/* control register masks */
44	#define	INT_ENABLE	(1 << 0)
45	#define	RESET_ENABLE	(1 << 1)
46#define WDTINTCLR		0x00C
47#define WDTRIS			0x010
48#define WDTMIS			0x014
49	#define INT_MASK	(1 << 0)
50#define WDTLOCK			0xC00
51	#define	UNLOCK		0x1ACCE551
52	#define	LOCK		0x00000001
53
54/**
55 * struct sp805_wdt: sp805 wdt device structure
56 * @wdd: instance of struct watchdog_device
57 * @lock: spin lock protecting dev structure and io access
58 * @base: base address of wdt
59 * @clk: clock structure of wdt
60 * @adev: amba device structure of wdt
61 * @status: current status of wdt
62 * @load_val: load value to be set for current timeout
63 * @timeout: current programmed timeout
64 */
65struct sp805_wdt {
66	struct watchdog_device		wdd;
67	spinlock_t			lock;
68	void __iomem			*base;
69	struct clk			*clk;
70	struct amba_device		*adev;
71	unsigned int			load_val;
72	unsigned int			timeout;
73};
74
75static bool nowayout = WATCHDOG_NOWAYOUT;
76module_param(nowayout, bool, 0);
77MODULE_PARM_DESC(nowayout,
78		"Set to 1 to keep watchdog running after device release");
79
80/* This routine finds load value that will reset system in required timout */
81static int wdt_setload(struct watchdog_device *wdd, unsigned int timeout)
82{
83	struct sp805_wdt *wdt = watchdog_get_drvdata(wdd);
84	u64 load, rate;
85
86	rate = clk_get_rate(wdt->clk);
87
88	/*
89	 * sp805 runs counter with given value twice, after the end of first
90	 * counter it gives an interrupt and then starts counter again. If
91	 * interrupt already occurred then it resets the system. This is why
92	 * load is half of what should be required.
93	 */
94	load = div_u64(rate, 2) * timeout - 1;
95
96	load = (load > LOAD_MAX) ? LOAD_MAX : load;
97	load = (load < LOAD_MIN) ? LOAD_MIN : load;
98
99	spin_lock(&wdt->lock);
100	wdt->load_val = load;
101	/* roundup timeout to closest positive integer value */
102	wdt->timeout = div_u64((load + 1) * 2 + (rate / 2), rate);
103	spin_unlock(&wdt->lock);
104
105	return 0;
106}
107
108/* returns number of seconds left for reset to occur */
109static unsigned int wdt_timeleft(struct watchdog_device *wdd)
110{
111	struct sp805_wdt *wdt = watchdog_get_drvdata(wdd);
112	u64 load, rate;
113
114	rate = clk_get_rate(wdt->clk);
115
116	spin_lock(&wdt->lock);
117	load = readl_relaxed(wdt->base + WDTVALUE);
118
119	/*If the interrupt is inactive then time left is WDTValue + WDTLoad. */
120	if (!(readl_relaxed(wdt->base + WDTRIS) & INT_MASK))
121		load += wdt->load_val + 1;
122	spin_unlock(&wdt->lock);
123
124	return div_u64(load, rate);
125}
126
127static int wdt_config(struct watchdog_device *wdd, bool ping)
128{
129	struct sp805_wdt *wdt = watchdog_get_drvdata(wdd);
130	int ret;
131
132	if (!ping) {
133
134		ret = clk_prepare_enable(wdt->clk);
135		if (ret) {
136			dev_err(&wdt->adev->dev, "clock enable fail");
137			return ret;
138		}
139	}
140
141	spin_lock(&wdt->lock);
142
143	writel_relaxed(UNLOCK, wdt->base + WDTLOCK);
144	writel_relaxed(wdt->load_val, wdt->base + WDTLOAD);
145
146	if (!ping) {
147		writel_relaxed(INT_MASK, wdt->base + WDTINTCLR);
148		writel_relaxed(INT_ENABLE | RESET_ENABLE, wdt->base +
149				WDTCONTROL);
150	}
151
152	writel_relaxed(LOCK, wdt->base + WDTLOCK);
153
154	/* Flush posted writes. */
155	readl_relaxed(wdt->base + WDTLOCK);
156	spin_unlock(&wdt->lock);
157
158	return 0;
159}
160
161static int wdt_ping(struct watchdog_device *wdd)
162{
163	return wdt_config(wdd, true);
164}
165
166/* enables watchdog timers reset */
167static int wdt_enable(struct watchdog_device *wdd)
168{
169	return wdt_config(wdd, false);
170}
171
172/* disables watchdog timers reset */
173static int wdt_disable(struct watchdog_device *wdd)
174{
175	struct sp805_wdt *wdt = watchdog_get_drvdata(wdd);
176
177	spin_lock(&wdt->lock);
178
179	writel_relaxed(UNLOCK, wdt->base + WDTLOCK);
180	writel_relaxed(0, wdt->base + WDTCONTROL);
181	writel_relaxed(LOCK, wdt->base + WDTLOCK);
182
183	/* Flush posted writes. */
184	readl_relaxed(wdt->base + WDTLOCK);
185	spin_unlock(&wdt->lock);
186
187	clk_disable_unprepare(wdt->clk);
188
189	return 0;
190}
191
192static const struct watchdog_info wdt_info = {
193	.options = WDIOF_MAGICCLOSE | WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING,
194	.identity = MODULE_NAME,
195};
196
197static const struct watchdog_ops wdt_ops = {
198	.owner		= THIS_MODULE,
199	.start		= wdt_enable,
200	.stop		= wdt_disable,
201	.ping		= wdt_ping,
202	.set_timeout	= wdt_setload,
203	.get_timeleft	= wdt_timeleft,
204};
205
206static int
207sp805_wdt_probe(struct amba_device *adev, const struct amba_id *id)
208{
209	struct sp805_wdt *wdt;
210	int ret = 0;
211
212	if (!devm_request_mem_region(&adev->dev, adev->res.start,
213				resource_size(&adev->res), "sp805_wdt")) {
214		dev_warn(&adev->dev, "Failed to get memory region resource\n");
215		ret = -ENOENT;
216		goto err;
217	}
218
219	wdt = devm_kzalloc(&adev->dev, sizeof(*wdt), GFP_KERNEL);
220	if (!wdt) {
221		dev_warn(&adev->dev, "Kzalloc failed\n");
222		ret = -ENOMEM;
223		goto err;
224	}
225
226	wdt->base = devm_ioremap(&adev->dev, adev->res.start,
227			resource_size(&adev->res));
228	if (!wdt->base) {
229		ret = -ENOMEM;
230		dev_warn(&adev->dev, "ioremap fail\n");
231		goto err;
232	}
233
234	wdt->clk = devm_clk_get(&adev->dev, NULL);
235	if (IS_ERR(wdt->clk)) {
236		dev_warn(&adev->dev, "Clock not found\n");
237		ret = PTR_ERR(wdt->clk);
238		goto err;
239	}
240
241	wdt->adev = adev;
242	wdt->wdd.info = &wdt_info;
243	wdt->wdd.ops = &wdt_ops;
244
245	spin_lock_init(&wdt->lock);
246	watchdog_set_nowayout(&wdt->wdd, nowayout);
247	watchdog_set_drvdata(&wdt->wdd, wdt);
248	wdt_setload(&wdt->wdd, DEFAULT_TIMEOUT);
249
250	ret = watchdog_register_device(&wdt->wdd);
251	if (ret) {
252		dev_err(&adev->dev, "watchdog_register_device() failed: %d\n",
253				ret);
254		goto err;
255	}
256	amba_set_drvdata(adev, wdt);
257
258	dev_info(&adev->dev, "registration successful\n");
259	return 0;
260
261err:
262	dev_err(&adev->dev, "Probe Failed!!!\n");
263	return ret;
264}
265
266static int sp805_wdt_remove(struct amba_device *adev)
267{
268	struct sp805_wdt *wdt = amba_get_drvdata(adev);
269
270	watchdog_unregister_device(&wdt->wdd);
271	watchdog_set_drvdata(&wdt->wdd, NULL);
272
273	return 0;
274}
275
276static int __maybe_unused sp805_wdt_suspend(struct device *dev)
277{
278	struct sp805_wdt *wdt = dev_get_drvdata(dev);
279
280	if (watchdog_active(&wdt->wdd))
281		return wdt_disable(&wdt->wdd);
282
283	return 0;
284}
285
286static int __maybe_unused sp805_wdt_resume(struct device *dev)
287{
288	struct sp805_wdt *wdt = dev_get_drvdata(dev);
289
290	if (watchdog_active(&wdt->wdd))
291		return wdt_enable(&wdt->wdd);
292
293	return 0;
294}
295
296static SIMPLE_DEV_PM_OPS(sp805_wdt_dev_pm_ops, sp805_wdt_suspend,
297		sp805_wdt_resume);
298
299static struct amba_id sp805_wdt_ids[] = {
300	{
301		.id	= 0x00141805,
302		.mask	= 0x00ffffff,
303	},
304	{ 0, 0 },
305};
306
307MODULE_DEVICE_TABLE(amba, sp805_wdt_ids);
308
309static struct amba_driver sp805_wdt_driver = {
310	.drv = {
311		.name	= MODULE_NAME,
312		.pm	= &sp805_wdt_dev_pm_ops,
313	},
314	.id_table	= sp805_wdt_ids,
315	.probe		= sp805_wdt_probe,
316	.remove = sp805_wdt_remove,
317};
318
319module_amba_driver(sp805_wdt_driver);
320
321MODULE_AUTHOR("Viresh Kumar <viresh.linux@gmail.com>");
322MODULE_DESCRIPTION("ARM SP805 Watchdog Driver");
323MODULE_LICENSE("GPL");
324