1/*
2 * Watchdog driver for the wm831x PMICs
3 *
4 * Copyright (C) 2009 Wolfson Microelectronics
5 *
6 * This program is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU General Public License
8 * as published by the Free Software Foundation
9 */
10
11#include <linux/module.h>
12#include <linux/moduleparam.h>
13#include <linux/types.h>
14#include <linux/kernel.h>
15#include <linux/slab.h>
16#include <linux/platform_device.h>
17#include <linux/watchdog.h>
18#include <linux/uaccess.h>
19#include <linux/gpio.h>
20
21#include <linux/mfd/wm831x/core.h>
22#include <linux/mfd/wm831x/pdata.h>
23#include <linux/mfd/wm831x/watchdog.h>
24
25static bool nowayout = WATCHDOG_NOWAYOUT;
26module_param(nowayout, bool, 0);
27MODULE_PARM_DESC(nowayout,
28		 "Watchdog cannot be stopped once started (default="
29		 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
30
31struct wm831x_wdt_drvdata {
32	struct watchdog_device wdt;
33	struct wm831x *wm831x;
34	struct mutex lock;
35	int update_gpio;
36	int update_state;
37};
38
39/* We can't use the sub-second values here but they're included
40 * for completeness.  */
41static struct {
42	unsigned int time;  /* Seconds */
43	u16 val;            /* WDOG_TO value */
44} wm831x_wdt_cfgs[] = {
45	{  1, 2 },
46	{  2, 3 },
47	{  4, 4 },
48	{  8, 5 },
49	{ 16, 6 },
50	{ 32, 7 },
51	{ 33, 7 },  /* Actually 32.768s so include both, others round down */
52};
53
54static int wm831x_wdt_start(struct watchdog_device *wdt_dev)
55{
56	struct wm831x_wdt_drvdata *driver_data = watchdog_get_drvdata(wdt_dev);
57	struct wm831x *wm831x = driver_data->wm831x;
58	int ret;
59
60	mutex_lock(&driver_data->lock);
61
62	ret = wm831x_reg_unlock(wm831x);
63	if (ret == 0) {
64		ret = wm831x_set_bits(wm831x, WM831X_WATCHDOG,
65				      WM831X_WDOG_ENA, WM831X_WDOG_ENA);
66		wm831x_reg_lock(wm831x);
67	} else {
68		dev_err(wm831x->dev, "Failed to unlock security key: %d\n",
69			ret);
70	}
71
72	mutex_unlock(&driver_data->lock);
73
74	return ret;
75}
76
77static int wm831x_wdt_stop(struct watchdog_device *wdt_dev)
78{
79	struct wm831x_wdt_drvdata *driver_data = watchdog_get_drvdata(wdt_dev);
80	struct wm831x *wm831x = driver_data->wm831x;
81	int ret;
82
83	mutex_lock(&driver_data->lock);
84
85	ret = wm831x_reg_unlock(wm831x);
86	if (ret == 0) {
87		ret = wm831x_set_bits(wm831x, WM831X_WATCHDOG,
88				      WM831X_WDOG_ENA, 0);
89		wm831x_reg_lock(wm831x);
90	} else {
91		dev_err(wm831x->dev, "Failed to unlock security key: %d\n",
92			ret);
93	}
94
95	mutex_unlock(&driver_data->lock);
96
97	return ret;
98}
99
100static int wm831x_wdt_ping(struct watchdog_device *wdt_dev)
101{
102	struct wm831x_wdt_drvdata *driver_data = watchdog_get_drvdata(wdt_dev);
103	struct wm831x *wm831x = driver_data->wm831x;
104	int ret;
105	u16 reg;
106
107	mutex_lock(&driver_data->lock);
108
109	if (driver_data->update_gpio) {
110		gpio_set_value_cansleep(driver_data->update_gpio,
111					driver_data->update_state);
112		driver_data->update_state = !driver_data->update_state;
113		ret = 0;
114		goto out;
115	}
116
117	reg = wm831x_reg_read(wm831x, WM831X_WATCHDOG);
118
119	if (!(reg & WM831X_WDOG_RST_SRC)) {
120		dev_err(wm831x->dev, "Hardware watchdog update unsupported\n");
121		ret = -EINVAL;
122		goto out;
123	}
124
125	reg |= WM831X_WDOG_RESET;
126
127	ret = wm831x_reg_unlock(wm831x);
128	if (ret == 0) {
129		ret = wm831x_reg_write(wm831x, WM831X_WATCHDOG, reg);
130		wm831x_reg_lock(wm831x);
131	} else {
132		dev_err(wm831x->dev, "Failed to unlock security key: %d\n",
133			ret);
134	}
135
136out:
137	mutex_unlock(&driver_data->lock);
138
139	return ret;
140}
141
142static int wm831x_wdt_set_timeout(struct watchdog_device *wdt_dev,
143				  unsigned int timeout)
144{
145	struct wm831x_wdt_drvdata *driver_data = watchdog_get_drvdata(wdt_dev);
146	struct wm831x *wm831x = driver_data->wm831x;
147	int ret, i;
148
149	for (i = 0; i < ARRAY_SIZE(wm831x_wdt_cfgs); i++)
150		if (wm831x_wdt_cfgs[i].time == timeout)
151			break;
152	if (i == ARRAY_SIZE(wm831x_wdt_cfgs))
153		return -EINVAL;
154
155	ret = wm831x_reg_unlock(wm831x);
156	if (ret == 0) {
157		ret = wm831x_set_bits(wm831x, WM831X_WATCHDOG,
158				      WM831X_WDOG_TO_MASK,
159				      wm831x_wdt_cfgs[i].val);
160		wm831x_reg_lock(wm831x);
161	} else {
162		dev_err(wm831x->dev, "Failed to unlock security key: %d\n",
163			ret);
164	}
165
166	wdt_dev->timeout = timeout;
167
168	return ret;
169}
170
171static const struct watchdog_info wm831x_wdt_info = {
172	.options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
173	.identity = "WM831x Watchdog",
174};
175
176static const struct watchdog_ops wm831x_wdt_ops = {
177	.owner = THIS_MODULE,
178	.start = wm831x_wdt_start,
179	.stop = wm831x_wdt_stop,
180	.ping = wm831x_wdt_ping,
181	.set_timeout = wm831x_wdt_set_timeout,
182};
183
184static int wm831x_wdt_probe(struct platform_device *pdev)
185{
186	struct wm831x *wm831x = dev_get_drvdata(pdev->dev.parent);
187	struct wm831x_pdata *chip_pdata = dev_get_platdata(pdev->dev.parent);
188	struct wm831x_watchdog_pdata *pdata;
189	struct wm831x_wdt_drvdata *driver_data;
190	struct watchdog_device *wm831x_wdt;
191	int reg, ret, i;
192
193	ret = wm831x_reg_read(wm831x, WM831X_WATCHDOG);
194	if (ret < 0) {
195		dev_err(wm831x->dev, "Failed to read watchdog status: %d\n",
196			ret);
197		goto err;
198	}
199	reg = ret;
200
201	if (reg & WM831X_WDOG_DEBUG)
202		dev_warn(wm831x->dev, "Watchdog is paused\n");
203
204	driver_data = devm_kzalloc(&pdev->dev, sizeof(*driver_data),
205				   GFP_KERNEL);
206	if (!driver_data) {
207		ret = -ENOMEM;
208		goto err;
209	}
210
211	mutex_init(&driver_data->lock);
212	driver_data->wm831x = wm831x;
213
214	wm831x_wdt = &driver_data->wdt;
215
216	wm831x_wdt->info = &wm831x_wdt_info;
217	wm831x_wdt->ops = &wm831x_wdt_ops;
218	wm831x_wdt->parent = &pdev->dev;
219	watchdog_set_nowayout(wm831x_wdt, nowayout);
220	watchdog_set_drvdata(wm831x_wdt, driver_data);
221
222	reg = wm831x_reg_read(wm831x, WM831X_WATCHDOG);
223	reg &= WM831X_WDOG_TO_MASK;
224	for (i = 0; i < ARRAY_SIZE(wm831x_wdt_cfgs); i++)
225		if (wm831x_wdt_cfgs[i].val == reg)
226			break;
227	if (i == ARRAY_SIZE(wm831x_wdt_cfgs))
228		dev_warn(wm831x->dev,
229			 "Unknown watchdog timeout: %x\n", reg);
230	else
231		wm831x_wdt->timeout = wm831x_wdt_cfgs[i].time;
232
233	/* Apply any configuration */
234	if (chip_pdata)
235		pdata = chip_pdata->watchdog;
236	else
237		pdata = NULL;
238
239	if (pdata) {
240		reg &= ~(WM831X_WDOG_SECACT_MASK | WM831X_WDOG_PRIMACT_MASK |
241			 WM831X_WDOG_RST_SRC);
242
243		reg |= pdata->primary << WM831X_WDOG_PRIMACT_SHIFT;
244		reg |= pdata->secondary << WM831X_WDOG_SECACT_SHIFT;
245		reg |= pdata->software << WM831X_WDOG_RST_SRC_SHIFT;
246
247		if (pdata->update_gpio) {
248			ret = devm_gpio_request_one(&pdev->dev,
249						pdata->update_gpio,
250						GPIOF_OUT_INIT_LOW,
251						"Watchdog update");
252			if (ret < 0) {
253				dev_err(wm831x->dev,
254					"Failed to request update GPIO: %d\n",
255					ret);
256				goto err;
257			}
258
259			driver_data->update_gpio = pdata->update_gpio;
260
261			/* Make sure the watchdog takes hardware updates */
262			reg |= WM831X_WDOG_RST_SRC;
263		}
264
265		ret = wm831x_reg_unlock(wm831x);
266		if (ret == 0) {
267			ret = wm831x_reg_write(wm831x, WM831X_WATCHDOG, reg);
268			wm831x_reg_lock(wm831x);
269		} else {
270			dev_err(wm831x->dev,
271				"Failed to unlock security key: %d\n", ret);
272			goto err;
273		}
274	}
275
276	ret = watchdog_register_device(&driver_data->wdt);
277	if (ret != 0) {
278		dev_err(wm831x->dev, "watchdog_register_device() failed: %d\n",
279			ret);
280		goto err;
281	}
282
283	platform_set_drvdata(pdev, driver_data);
284
285	return 0;
286
287err:
288	return ret;
289}
290
291static int wm831x_wdt_remove(struct platform_device *pdev)
292{
293	struct wm831x_wdt_drvdata *driver_data = platform_get_drvdata(pdev);
294
295	watchdog_unregister_device(&driver_data->wdt);
296
297	return 0;
298}
299
300static struct platform_driver wm831x_wdt_driver = {
301	.probe = wm831x_wdt_probe,
302	.remove = wm831x_wdt_remove,
303	.driver = {
304		.name = "wm831x-watchdog",
305	},
306};
307
308module_platform_driver(wm831x_wdt_driver);
309
310MODULE_AUTHOR("Mark Brown");
311MODULE_DESCRIPTION("WM831x Watchdog");
312MODULE_LICENSE("GPL");
313MODULE_ALIAS("platform:wm831x-watchdog");
314