1 // SPDX-License-Identifier: GPL-2.0+
2 /*
3  * Watchdog driver for the wm831x PMICs
4  *
5  * Copyright (C) 2009 Wolfson Microelectronics
6  */
7 
8 #include <linux/module.h>
9 #include <linux/moduleparam.h>
10 #include <linux/types.h>
11 #include <linux/kernel.h>
12 #include <linux/slab.h>
13 #include <linux/platform_device.h>
14 #include <linux/watchdog.h>
15 #include <linux/uaccess.h>
16 #include <linux/gpio.h>
17 
18 #include <linux/mfd/wm831x/core.h>
19 #include <linux/mfd/wm831x/pdata.h>
20 #include <linux/mfd/wm831x/watchdog.h>
21 
22 static bool nowayout = WATCHDOG_NOWAYOUT;
23 module_param(nowayout, bool, 0);
24 MODULE_PARM_DESC(nowayout,
25 		 "Watchdog cannot be stopped once started (default="
26 		 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
27 
28 struct wm831x_wdt_drvdata {
29 	struct watchdog_device wdt;
30 	struct wm831x *wm831x;
31 	struct mutex lock;
32 	int update_gpio;
33 	int update_state;
34 };
35 
36 /* We can't use the sub-second values here but they're included
37  * for completeness.  */
38 static struct {
39 	unsigned int time;  /* Seconds */
40 	u16 val;            /* WDOG_TO value */
41 } wm831x_wdt_cfgs[] = {
42 	{  1, 2 },
43 	{  2, 3 },
44 	{  4, 4 },
45 	{  8, 5 },
46 	{ 16, 6 },
47 	{ 32, 7 },
48 	{ 33, 7 },  /* Actually 32.768s so include both, others round down */
49 };
50 
wm831x_wdt_start(struct watchdog_device * wdt_dev)51 static int wm831x_wdt_start(struct watchdog_device *wdt_dev)
52 {
53 	struct wm831x_wdt_drvdata *driver_data = watchdog_get_drvdata(wdt_dev);
54 	struct wm831x *wm831x = driver_data->wm831x;
55 	int ret;
56 
57 	mutex_lock(&driver_data->lock);
58 
59 	ret = wm831x_reg_unlock(wm831x);
60 	if (ret == 0) {
61 		ret = wm831x_set_bits(wm831x, WM831X_WATCHDOG,
62 				      WM831X_WDOG_ENA, WM831X_WDOG_ENA);
63 		wm831x_reg_lock(wm831x);
64 	} else {
65 		dev_err(wm831x->dev, "Failed to unlock security key: %d\n",
66 			ret);
67 	}
68 
69 	mutex_unlock(&driver_data->lock);
70 
71 	return ret;
72 }
73 
wm831x_wdt_stop(struct watchdog_device * wdt_dev)74 static int wm831x_wdt_stop(struct watchdog_device *wdt_dev)
75 {
76 	struct wm831x_wdt_drvdata *driver_data = watchdog_get_drvdata(wdt_dev);
77 	struct wm831x *wm831x = driver_data->wm831x;
78 	int ret;
79 
80 	mutex_lock(&driver_data->lock);
81 
82 	ret = wm831x_reg_unlock(wm831x);
83 	if (ret == 0) {
84 		ret = wm831x_set_bits(wm831x, WM831X_WATCHDOG,
85 				      WM831X_WDOG_ENA, 0);
86 		wm831x_reg_lock(wm831x);
87 	} else {
88 		dev_err(wm831x->dev, "Failed to unlock security key: %d\n",
89 			ret);
90 	}
91 
92 	mutex_unlock(&driver_data->lock);
93 
94 	return ret;
95 }
96 
wm831x_wdt_ping(struct watchdog_device * wdt_dev)97 static int wm831x_wdt_ping(struct watchdog_device *wdt_dev)
98 {
99 	struct wm831x_wdt_drvdata *driver_data = watchdog_get_drvdata(wdt_dev);
100 	struct wm831x *wm831x = driver_data->wm831x;
101 	int ret;
102 	u16 reg;
103 
104 	mutex_lock(&driver_data->lock);
105 
106 	if (driver_data->update_gpio) {
107 		gpio_set_value_cansleep(driver_data->update_gpio,
108 					driver_data->update_state);
109 		driver_data->update_state = !driver_data->update_state;
110 		ret = 0;
111 		goto out;
112 	}
113 
114 	reg = wm831x_reg_read(wm831x, WM831X_WATCHDOG);
115 
116 	if (!(reg & WM831X_WDOG_RST_SRC)) {
117 		dev_err(wm831x->dev, "Hardware watchdog update unsupported\n");
118 		ret = -EINVAL;
119 		goto out;
120 	}
121 
122 	reg |= WM831X_WDOG_RESET;
123 
124 	ret = wm831x_reg_unlock(wm831x);
125 	if (ret == 0) {
126 		ret = wm831x_reg_write(wm831x, WM831X_WATCHDOG, reg);
127 		wm831x_reg_lock(wm831x);
128 	} else {
129 		dev_err(wm831x->dev, "Failed to unlock security key: %d\n",
130 			ret);
131 	}
132 
133 out:
134 	mutex_unlock(&driver_data->lock);
135 
136 	return ret;
137 }
138 
wm831x_wdt_set_timeout(struct watchdog_device * wdt_dev,unsigned int timeout)139 static int wm831x_wdt_set_timeout(struct watchdog_device *wdt_dev,
140 				  unsigned int timeout)
141 {
142 	struct wm831x_wdt_drvdata *driver_data = watchdog_get_drvdata(wdt_dev);
143 	struct wm831x *wm831x = driver_data->wm831x;
144 	int ret, i;
145 
146 	for (i = 0; i < ARRAY_SIZE(wm831x_wdt_cfgs); i++)
147 		if (wm831x_wdt_cfgs[i].time == timeout)
148 			break;
149 	if (i == ARRAY_SIZE(wm831x_wdt_cfgs))
150 		return -EINVAL;
151 
152 	ret = wm831x_reg_unlock(wm831x);
153 	if (ret == 0) {
154 		ret = wm831x_set_bits(wm831x, WM831X_WATCHDOG,
155 				      WM831X_WDOG_TO_MASK,
156 				      wm831x_wdt_cfgs[i].val);
157 		wm831x_reg_lock(wm831x);
158 	} else {
159 		dev_err(wm831x->dev, "Failed to unlock security key: %d\n",
160 			ret);
161 	}
162 
163 	wdt_dev->timeout = timeout;
164 
165 	return ret;
166 }
167 
168 static const struct watchdog_info wm831x_wdt_info = {
169 	.options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
170 	.identity = "WM831x Watchdog",
171 };
172 
173 static const struct watchdog_ops wm831x_wdt_ops = {
174 	.owner = THIS_MODULE,
175 	.start = wm831x_wdt_start,
176 	.stop = wm831x_wdt_stop,
177 	.ping = wm831x_wdt_ping,
178 	.set_timeout = wm831x_wdt_set_timeout,
179 };
180 
wm831x_wdt_probe(struct platform_device * pdev)181 static int wm831x_wdt_probe(struct platform_device *pdev)
182 {
183 	struct device *dev = &pdev->dev;
184 	struct wm831x *wm831x = dev_get_drvdata(dev->parent);
185 	struct wm831x_pdata *chip_pdata = dev_get_platdata(dev->parent);
186 	struct wm831x_watchdog_pdata *pdata;
187 	struct wm831x_wdt_drvdata *driver_data;
188 	struct watchdog_device *wm831x_wdt;
189 	int reg, ret, i;
190 
191 	ret = wm831x_reg_read(wm831x, WM831X_WATCHDOG);
192 	if (ret < 0) {
193 		dev_err(wm831x->dev, "Failed to read watchdog status: %d\n",
194 			ret);
195 		return ret;
196 	}
197 	reg = ret;
198 
199 	if (reg & WM831X_WDOG_DEBUG)
200 		dev_warn(wm831x->dev, "Watchdog is paused\n");
201 
202 	driver_data = devm_kzalloc(dev, sizeof(*driver_data), GFP_KERNEL);
203 	if (!driver_data)
204 		return -ENOMEM;
205 
206 	mutex_init(&driver_data->lock);
207 	driver_data->wm831x = wm831x;
208 
209 	wm831x_wdt = &driver_data->wdt;
210 
211 	wm831x_wdt->info = &wm831x_wdt_info;
212 	wm831x_wdt->ops = &wm831x_wdt_ops;
213 	wm831x_wdt->parent = dev;
214 	watchdog_set_nowayout(wm831x_wdt, nowayout);
215 	watchdog_set_drvdata(wm831x_wdt, driver_data);
216 
217 	reg = wm831x_reg_read(wm831x, WM831X_WATCHDOG);
218 	reg &= WM831X_WDOG_TO_MASK;
219 	for (i = 0; i < ARRAY_SIZE(wm831x_wdt_cfgs); i++)
220 		if (wm831x_wdt_cfgs[i].val == reg)
221 			break;
222 	if (i == ARRAY_SIZE(wm831x_wdt_cfgs))
223 		dev_warn(wm831x->dev,
224 			 "Unknown watchdog timeout: %x\n", reg);
225 	else
226 		wm831x_wdt->timeout = wm831x_wdt_cfgs[i].time;
227 
228 	/* Apply any configuration */
229 	if (chip_pdata)
230 		pdata = chip_pdata->watchdog;
231 	else
232 		pdata = NULL;
233 
234 	if (pdata) {
235 		reg &= ~(WM831X_WDOG_SECACT_MASK | WM831X_WDOG_PRIMACT_MASK |
236 			 WM831X_WDOG_RST_SRC);
237 
238 		reg |= pdata->primary << WM831X_WDOG_PRIMACT_SHIFT;
239 		reg |= pdata->secondary << WM831X_WDOG_SECACT_SHIFT;
240 		reg |= pdata->software << WM831X_WDOG_RST_SRC_SHIFT;
241 
242 		if (pdata->update_gpio) {
243 			ret = devm_gpio_request_one(dev, pdata->update_gpio,
244 						    GPIOF_OUT_INIT_LOW,
245 						    "Watchdog update");
246 			if (ret < 0) {
247 				dev_err(wm831x->dev,
248 					"Failed to request update GPIO: %d\n",
249 					ret);
250 				return ret;
251 			}
252 
253 			driver_data->update_gpio = pdata->update_gpio;
254 
255 			/* Make sure the watchdog takes hardware updates */
256 			reg |= WM831X_WDOG_RST_SRC;
257 		}
258 
259 		ret = wm831x_reg_unlock(wm831x);
260 		if (ret == 0) {
261 			ret = wm831x_reg_write(wm831x, WM831X_WATCHDOG, reg);
262 			wm831x_reg_lock(wm831x);
263 		} else {
264 			dev_err(wm831x->dev,
265 				"Failed to unlock security key: %d\n", ret);
266 			return ret;
267 		}
268 	}
269 
270 	return devm_watchdog_register_device(dev, &driver_data->wdt);
271 }
272 
273 static struct platform_driver wm831x_wdt_driver = {
274 	.probe = wm831x_wdt_probe,
275 	.driver = {
276 		.name = "wm831x-watchdog",
277 	},
278 };
279 
280 module_platform_driver(wm831x_wdt_driver);
281 
282 MODULE_AUTHOR("Mark Brown");
283 MODULE_DESCRIPTION("WM831x Watchdog");
284 MODULE_LICENSE("GPL");
285 MODULE_ALIAS("platform:wm831x-watchdog");
286