sp805_wdt.c revision 8deea830644c0a4bdd90dfda7249d0f40f0667fa 
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 */
64struct 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
74static bool nowayout = WATCHDOG_NOWAYOUT;
75module_param(nowayout, bool, 0);
76MODULE_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 */
80static 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 */
108static 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
126static 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
160static int wdt_ping(struct watchdog_device *wdd)
161{
162	return wdt_config(wdd, true);
163}
164
165/* enables watchdog timers reset */
166static int wdt_enable(struct watchdog_device *wdd)
167{
168	return wdt_config(wdd, false);
169}
170
171/* disables watchdog timers reset */
172static 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
191static const struct watchdog_info wdt_info = {
192	.options = WDIOF_MAGICCLOSE | WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING,
193	.identity = MODULE_NAME,
194};
195
196static 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
205static int
206sp805_wdt_probe(struct amba_device *adev, const struct amba_id *id)
207{
208	struct sp805_wdt *wdt;
209	int ret = 0;
210
211	if (!devm_request_mem_region(&adev->dev, adev->res.start,
212				resource_size(&adev->res), "sp805_wdt")) {
213		dev_warn(&adev->dev, "Failed to get memory region resource\n");
214		ret = -ENOENT;
215		goto err;
216	}
217
218	wdt = devm_kzalloc(&adev->dev, sizeof(*wdt), GFP_KERNEL);
219	if (!wdt) {
220		ret = -ENOMEM;
221		goto err;
222	}
223
224	wdt->base = devm_ioremap(&adev->dev, adev->res.start,
225			resource_size(&adev->res));
226	if (!wdt->base) {
227		ret = -ENOMEM;
228		dev_warn(&adev->dev, "ioremap fail\n");
229		goto err;
230	}
231
232	wdt->clk = devm_clk_get(&adev->dev, NULL);
233	if (IS_ERR(wdt->clk)) {
234		dev_warn(&adev->dev, "Clock not found\n");
235		ret = PTR_ERR(wdt->clk);
236		goto err;
237	}
238
239	wdt->adev = adev;
240	wdt->wdd.info = &wdt_info;
241	wdt->wdd.ops = &wdt_ops;
242
243	spin_lock_init(&wdt->lock);
244	watchdog_set_nowayout(&wdt->wdd, nowayout);
245	watchdog_set_drvdata(&wdt->wdd, wdt);
246	wdt_setload(&wdt->wdd, DEFAULT_TIMEOUT);
247
248	ret = watchdog_register_device(&wdt->wdd);
249	if (ret) {
250		dev_err(&adev->dev, "watchdog_register_device() failed: %d\n",
251				ret);
252		goto err;
253	}
254	amba_set_drvdata(adev, wdt);
255
256	dev_info(&adev->dev, "registration successful\n");
257	return 0;
258
259err:
260	dev_err(&adev->dev, "Probe Failed!!!\n");
261	return ret;
262}
263
264static int sp805_wdt_remove(struct amba_device *adev)
265{
266	struct sp805_wdt *wdt = amba_get_drvdata(adev);
267
268	watchdog_unregister_device(&wdt->wdd);
269	watchdog_set_drvdata(&wdt->wdd, NULL);
270
271	return 0;
272}
273
274static int __maybe_unused sp805_wdt_suspend(struct device *dev)
275{
276	struct sp805_wdt *wdt = dev_get_drvdata(dev);
277
278	if (watchdog_active(&wdt->wdd))
279		return wdt_disable(&wdt->wdd);
280
281	return 0;
282}
283
284static int __maybe_unused sp805_wdt_resume(struct device *dev)
285{
286	struct sp805_wdt *wdt = dev_get_drvdata(dev);
287
288	if (watchdog_active(&wdt->wdd))
289		return wdt_enable(&wdt->wdd);
290
291	return 0;
292}
293
294static SIMPLE_DEV_PM_OPS(sp805_wdt_dev_pm_ops, sp805_wdt_suspend,
295		sp805_wdt_resume);
296
297static struct amba_id sp805_wdt_ids[] = {
298	{
299		.id	= 0x00141805,
300		.mask	= 0x00ffffff,
301	},
302	{ 0, 0 },
303};
304
305MODULE_DEVICE_TABLE(amba, sp805_wdt_ids);
306
307static struct amba_driver sp805_wdt_driver = {
308	.drv = {
309		.name	= MODULE_NAME,
310		.pm	= &sp805_wdt_dev_pm_ops,
311	},
312	.id_table	= sp805_wdt_ids,
313	.probe		= sp805_wdt_probe,
314	.remove = sp805_wdt_remove,
315};
316
317module_amba_driver(sp805_wdt_driver);
318
319MODULE_AUTHOR("Viresh Kumar <viresh.linux@gmail.com>");
320MODULE_DESCRIPTION("ARM SP805 Watchdog Driver");
321MODULE_LICENSE("GPL");
322