da9063_wdt.c

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