xref: /openbmc/linux/drivers/watchdog/da9063_wdt.c (revision f8ee39b4)
1 // SPDX-License-Identifier: GPL-2.0+
2 /*
3  * Watchdog driver for DA9063 PMICs.
4  *
5  * Copyright(c) 2012 Dialog Semiconductor Ltd.
6  *
7  * Author: Mariusz Wojtasik <mariusz.wojtasik@diasemi.com>
8  *
9  */
10 
11 #include <linux/kernel.h>
12 #include <linux/module.h>
13 #include <linux/watchdog.h>
14 #include <linux/platform_device.h>
15 #include <linux/uaccess.h>
16 #include <linux/slab.h>
17 #include <linux/i2c.h>
18 #include <linux/delay.h>
19 #include <linux/mfd/da9063/registers.h>
20 #include <linux/mfd/da9063/core.h>
21 #include <linux/property.h>
22 #include <linux/regmap.h>
23 
24 /*
25  * Watchdog selector to timeout in seconds.
26  *   0: WDT disabled;
27  *   others: timeout = 2048 ms * 2^(TWDSCALE-1).
28  */
29 static const unsigned int wdt_timeout[] = { 0, 2, 4, 8, 16, 32, 65, 131 };
30 static bool use_sw_pm;
31 
32 #define DA9063_TWDSCALE_DISABLE		0
33 #define DA9063_TWDSCALE_MIN		1
34 #define DA9063_TWDSCALE_MAX		(ARRAY_SIZE(wdt_timeout) - 1)
35 #define DA9063_WDT_MIN_TIMEOUT		wdt_timeout[DA9063_TWDSCALE_MIN]
36 #define DA9063_WDT_MAX_TIMEOUT		wdt_timeout[DA9063_TWDSCALE_MAX]
37 #define DA9063_WDG_TIMEOUT		wdt_timeout[3]
38 #define DA9063_RESET_PROTECTION_MS	256
39 
da9063_wdt_timeout_to_sel(unsigned int secs)40 static unsigned int da9063_wdt_timeout_to_sel(unsigned int secs)
41 {
42 	unsigned int i;
43 
44 	for (i = DA9063_TWDSCALE_MIN; i <= DA9063_TWDSCALE_MAX; i++) {
45 		if (wdt_timeout[i] >= secs)
46 			return i;
47 	}
48 
49 	return DA9063_TWDSCALE_MAX;
50 }
51 
52 /*
53  * Read the currently active timeout.
54  * Zero means the watchdog is disabled.
55  */
da9063_wdt_read_timeout(struct da9063 * da9063)56 static unsigned int da9063_wdt_read_timeout(struct da9063 *da9063)
57 {
58 	unsigned int val;
59 
60 	regmap_read(da9063->regmap, DA9063_REG_CONTROL_D, &val);
61 
62 	return wdt_timeout[val & DA9063_TWDSCALE_MASK];
63 }
64 
da9063_wdt_disable_timer(struct da9063 * da9063)65 static int da9063_wdt_disable_timer(struct da9063 *da9063)
66 {
67 	return regmap_update_bits(da9063->regmap, DA9063_REG_CONTROL_D,
68 				  DA9063_TWDSCALE_MASK,
69 				  DA9063_TWDSCALE_DISABLE);
70 }
71 
72 static int
da9063_wdt_update_timeout(struct da9063 * da9063,unsigned int timeout)73 da9063_wdt_update_timeout(struct da9063 *da9063, unsigned int timeout)
74 {
75 	unsigned int regval;
76 	int ret;
77 
78 	/*
79 	 * The watchdog triggers a reboot if a timeout value is already
80 	 * programmed because the timeout value combines two functions
81 	 * in one: indicating the counter limit and starting the watchdog.
82 	 * The watchdog must be disabled to be able to change the timeout
83 	 * value if the watchdog is already running. Then we can set the
84 	 * new timeout value which enables the watchdog again.
85 	 */
86 	ret = da9063_wdt_disable_timer(da9063);
87 	if (ret)
88 		return ret;
89 
90 	usleep_range(150, 300);
91 	regval = da9063_wdt_timeout_to_sel(timeout);
92 
93 	return regmap_update_bits(da9063->regmap, DA9063_REG_CONTROL_D,
94 				  DA9063_TWDSCALE_MASK, regval);
95 }
96 
da9063_wdt_start(struct watchdog_device * wdd)97 static int da9063_wdt_start(struct watchdog_device *wdd)
98 {
99 	struct da9063 *da9063 = watchdog_get_drvdata(wdd);
100 	int ret;
101 
102 	ret = da9063_wdt_update_timeout(da9063, wdd->timeout);
103 	if (ret)
104 		dev_err(da9063->dev, "Watchdog failed to start (err = %d)\n",
105 			ret);
106 
107 	return ret;
108 }
109 
da9063_wdt_stop(struct watchdog_device * wdd)110 static int da9063_wdt_stop(struct watchdog_device *wdd)
111 {
112 	struct da9063 *da9063 = watchdog_get_drvdata(wdd);
113 	int ret;
114 
115 	ret = da9063_wdt_disable_timer(da9063);
116 	if (ret)
117 		dev_alert(da9063->dev, "Watchdog failed to stop (err = %d)\n",
118 			  ret);
119 
120 	return ret;
121 }
122 
da9063_wdt_ping(struct watchdog_device * wdd)123 static int da9063_wdt_ping(struct watchdog_device *wdd)
124 {
125 	struct da9063 *da9063 = watchdog_get_drvdata(wdd);
126 	int ret;
127 
128 	/*
129 	 * Prevent pings from occurring late in system poweroff/reboot sequence
130 	 * and possibly locking out restart handler from accessing i2c bus.
131 	 */
132 	if (system_state > SYSTEM_RUNNING)
133 		return 0;
134 
135 	ret = regmap_write(da9063->regmap, DA9063_REG_CONTROL_F,
136 			   DA9063_WATCHDOG);
137 	if (ret)
138 		dev_alert(da9063->dev, "Failed to ping the watchdog (err = %d)\n",
139 			  ret);
140 
141 	return ret;
142 }
143 
da9063_wdt_set_timeout(struct watchdog_device * wdd,unsigned int timeout)144 static int da9063_wdt_set_timeout(struct watchdog_device *wdd,
145 				  unsigned int timeout)
146 {
147 	struct da9063 *da9063 = watchdog_get_drvdata(wdd);
148 	int ret = 0;
149 
150 	/*
151 	 * There are two cases when a set_timeout() will be called:
152 	 * 1. The watchdog is off and someone wants to set the timeout for the
153 	 *    further use.
154 	 * 2. The watchdog is already running and a new timeout value should be
155 	 *    set.
156 	 *
157 	 * The watchdog can't store a timeout value not equal zero without
158 	 * enabling the watchdog, so the timeout must be buffered by the driver.
159 	 */
160 	if (watchdog_active(wdd))
161 		ret = da9063_wdt_update_timeout(da9063, timeout);
162 
163 	if (ret)
164 		dev_err(da9063->dev, "Failed to set watchdog timeout (err = %d)\n",
165 			ret);
166 	else
167 		wdd->timeout = wdt_timeout[da9063_wdt_timeout_to_sel(timeout)];
168 
169 	return ret;
170 }
171 
da9063_wdt_restart(struct watchdog_device * wdd,unsigned long action,void * data)172 static int da9063_wdt_restart(struct watchdog_device *wdd, unsigned long action,
173 			      void *data)
174 {
175 	struct da9063 *da9063 = watchdog_get_drvdata(wdd);
176 	struct i2c_client *client = to_i2c_client(da9063->dev);
177 	union i2c_smbus_data msg;
178 	int ret;
179 
180 	/*
181 	 * Don't use regmap because it is not atomic safe. Additionally, use
182 	 * unlocked flavor of i2c_smbus_xfer to avoid scenario where i2c bus
183 	 * might previously be locked by some process unable to release the
184 	 * lock due to interrupts already being disabled at this late stage.
185 	 */
186 	msg.byte = DA9063_SHUTDOWN;
187 	ret = __i2c_smbus_xfer(client->adapter, client->addr, client->flags,
188 			I2C_SMBUS_WRITE, DA9063_REG_CONTROL_F,
189 			I2C_SMBUS_BYTE_DATA, &msg);
190 
191 	if (ret < 0)
192 		dev_alert(da9063->dev, "Failed to shutdown (err = %d)\n",
193 			  ret);
194 
195 	/* wait for reset to assert... */
196 	mdelay(500);
197 
198 	return ret;
199 }
200 
201 static const struct watchdog_info da9063_watchdog_info = {
202 	.options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING,
203 	.identity = "DA9063 Watchdog",
204 };
205 
206 static const struct watchdog_ops da9063_watchdog_ops = {
207 	.owner = THIS_MODULE,
208 	.start = da9063_wdt_start,
209 	.stop = da9063_wdt_stop,
210 	.ping = da9063_wdt_ping,
211 	.set_timeout = da9063_wdt_set_timeout,
212 	.restart = da9063_wdt_restart,
213 };
214 
da9063_wdt_probe(struct platform_device * pdev)215 static int da9063_wdt_probe(struct platform_device *pdev)
216 {
217 	struct device *dev = &pdev->dev;
218 	struct da9063 *da9063;
219 	struct watchdog_device *wdd;
220 	unsigned int timeout;
221 
222 	if (!dev->parent)
223 		return -EINVAL;
224 
225 	da9063 = dev_get_drvdata(dev->parent);
226 	if (!da9063)
227 		return -EINVAL;
228 
229 	wdd = devm_kzalloc(dev, sizeof(*wdd), GFP_KERNEL);
230 	if (!wdd)
231 		return -ENOMEM;
232 
233 	use_sw_pm = device_property_present(dev, "dlg,use-sw-pm");
234 
235 	wdd->info = &da9063_watchdog_info;
236 	wdd->ops = &da9063_watchdog_ops;
237 	wdd->min_timeout = DA9063_WDT_MIN_TIMEOUT;
238 	wdd->max_timeout = DA9063_WDT_MAX_TIMEOUT;
239 	wdd->min_hw_heartbeat_ms = DA9063_RESET_PROTECTION_MS;
240 	wdd->parent = dev;
241 	wdd->status = WATCHDOG_NOWAYOUT_INIT_STATUS;
242 
243 	watchdog_set_restart_priority(wdd, 128);
244 	watchdog_set_drvdata(wdd, da9063);
245 	dev_set_drvdata(dev, wdd);
246 
247 	wdd->timeout = DA9063_WDG_TIMEOUT;
248 
249 	/* Use pre-configured timeout if watchdog is already running. */
250 	timeout = da9063_wdt_read_timeout(da9063);
251 	if (timeout)
252 		wdd->timeout = timeout;
253 
254 	/* Set timeout, maybe override it with DT value, scale it */
255 	watchdog_init_timeout(wdd, 0, dev);
256 	da9063_wdt_set_timeout(wdd, wdd->timeout);
257 
258 	/* Update timeout if the watchdog is already running. */
259 	if (timeout) {
260 		da9063_wdt_update_timeout(da9063, wdd->timeout);
261 		set_bit(WDOG_HW_RUNNING, &wdd->status);
262 	}
263 
264 	return devm_watchdog_register_device(dev, wdd);
265 }
266 
da9063_wdt_suspend(struct device * dev)267 static int __maybe_unused da9063_wdt_suspend(struct device *dev)
268 {
269 	struct watchdog_device *wdd = dev_get_drvdata(dev);
270 
271 	if (!use_sw_pm)
272 		return 0;
273 
274 	if (watchdog_active(wdd))
275 		return da9063_wdt_stop(wdd);
276 
277 	return 0;
278 }
279 
da9063_wdt_resume(struct device * dev)280 static int __maybe_unused da9063_wdt_resume(struct device *dev)
281 {
282 	struct watchdog_device *wdd = dev_get_drvdata(dev);
283 
284 	if (!use_sw_pm)
285 		return 0;
286 
287 	if (watchdog_active(wdd))
288 		return da9063_wdt_start(wdd);
289 
290 	return 0;
291 }
292 
293 static SIMPLE_DEV_PM_OPS(da9063_wdt_pm_ops,
294 			da9063_wdt_suspend, da9063_wdt_resume);
295 
296 static struct platform_driver da9063_wdt_driver = {
297 	.probe = da9063_wdt_probe,
298 	.driver = {
299 		.name = DA9063_DRVNAME_WATCHDOG,
300 		.pm = &da9063_wdt_pm_ops,
301 	},
302 };
303 module_platform_driver(da9063_wdt_driver);
304 
305 MODULE_AUTHOR("Mariusz Wojtasik <mariusz.wojtasik@diasemi.com>");
306 MODULE_DESCRIPTION("Watchdog driver for Dialog DA9063");
307 MODULE_LICENSE("GPL");
308 MODULE_ALIAS("platform:" DA9063_DRVNAME_WATCHDOG);
309