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/delay.h>
 18#include <linux/mfd/da9063/registers.h>
 19#include <linux/mfd/da9063/core.h>
 20#include <linux/regmap.h>
 21
 22/*
 23 * Watchdog selector to timeout in seconds.
 24 *   0: WDT disabled;
 25 *   others: timeout = 2048 ms * 2^(TWDSCALE-1).
 26 */
 27static const unsigned int wdt_timeout[] = { 0, 2, 4, 8, 16, 32, 65, 131 };
 28#define DA9063_TWDSCALE_DISABLE		0
 29#define DA9063_TWDSCALE_MIN		1
 30#define DA9063_TWDSCALE_MAX		(ARRAY_SIZE(wdt_timeout) - 1)
 31#define DA9063_WDT_MIN_TIMEOUT		wdt_timeout[DA9063_TWDSCALE_MIN]
 32#define DA9063_WDT_MAX_TIMEOUT		wdt_timeout[DA9063_TWDSCALE_MAX]
 33#define DA9063_WDG_TIMEOUT		wdt_timeout[3]
 34#define DA9063_RESET_PROTECTION_MS	256
 35
 36static unsigned int da9063_wdt_timeout_to_sel(unsigned int secs)
 37{
 38	unsigned int i;
 39
 40	for (i = DA9063_TWDSCALE_MIN; i <= DA9063_TWDSCALE_MAX; i++) {
 41		if (wdt_timeout[i] >= secs)
 42			return i;
 43	}
 44
 45	return DA9063_TWDSCALE_MAX;
 46}
 47
 48/*
 49 * Read the currently active timeout.
 50 * Zero means the watchdog is disabled.
 51 */
 52static unsigned int da9063_wdt_read_timeout(struct da9063 *da9063)
 53{
 54	unsigned int val;
 55
 56	regmap_read(da9063->regmap, DA9063_REG_CONTROL_D, &val);
 57
 58	return wdt_timeout[val & DA9063_TWDSCALE_MASK];
 59}
 60
 61static int da9063_wdt_disable_timer(struct da9063 *da9063)
 62{
 63	return regmap_update_bits(da9063->regmap, DA9063_REG_CONTROL_D,
 64				  DA9063_TWDSCALE_MASK,
 65				  DA9063_TWDSCALE_DISABLE);
 66}
 67
 68static int
 69da9063_wdt_update_timeout(struct da9063 *da9063, unsigned int timeout)
 70{
 71	unsigned int regval;
 72	int ret;
 73
 74	/*
 75	 * The watchdog triggers a reboot if a timeout value is already
 76	 * programmed because the timeout value combines two functions
 77	 * in one: indicating the counter limit and starting the watchdog.
 78	 * The watchdog must be disabled to be able to change the timeout
 79	 * value if the watchdog is already running. Then we can set the
 80	 * new timeout value which enables the watchdog again.
 81	 */
 82	ret = da9063_wdt_disable_timer(da9063);
 83	if (ret)
 84		return ret;
 85
 86	usleep_range(150, 300);
 87	regval = da9063_wdt_timeout_to_sel(timeout);
 88
 89	return regmap_update_bits(da9063->regmap, DA9063_REG_CONTROL_D,
 90				  DA9063_TWDSCALE_MASK, regval);
 91}
 92
 93static int da9063_wdt_start(struct watchdog_device *wdd)
 94{
 95	struct da9063 *da9063 = watchdog_get_drvdata(wdd);
 96	int ret;
 97
 98	ret = da9063_wdt_update_timeout(da9063, wdd->timeout);
 99	if (ret)
100		dev_err(da9063->dev, "Watchdog failed to start (err = %d)\n",
101			ret);
102
103	return ret;
104}
105
106static int da9063_wdt_stop(struct watchdog_device *wdd)
107{
108	struct da9063 *da9063 = watchdog_get_drvdata(wdd);
109	int ret;
110
111	ret = da9063_wdt_disable_timer(da9063);
112	if (ret)
113		dev_alert(da9063->dev, "Watchdog failed to stop (err = %d)\n",
114			  ret);
115
116	return ret;
117}
118
119static int da9063_wdt_ping(struct watchdog_device *wdd)
120{
121	struct da9063 *da9063 = watchdog_get_drvdata(wdd);
122	int ret;
123
124	ret = regmap_write(da9063->regmap, DA9063_REG_CONTROL_F,
125			   DA9063_WATCHDOG);
126	if (ret)
127		dev_alert(da9063->dev, "Failed to ping the watchdog (err = %d)\n",
128			  ret);
129
130	return ret;
131}
132
133static int da9063_wdt_set_timeout(struct watchdog_device *wdd,
134				  unsigned int timeout)
135{
136	struct da9063 *da9063 = watchdog_get_drvdata(wdd);
137	int ret = 0;
138
139	/*
140	 * There are two cases when a set_timeout() will be called:
141	 * 1. The watchdog is off and someone wants to set the timeout for the
142	 *    further use.
143	 * 2. The watchdog is already running and a new timeout value should be
144	 *    set.
145	 *
146	 * The watchdog can't store a timeout value not equal zero without
147	 * enabling the watchdog, so the timeout must be buffered by the driver.
148	 */
149	if (watchdog_active(wdd))
150		ret = da9063_wdt_update_timeout(da9063, timeout);
151
152	if (ret)
153		dev_err(da9063->dev, "Failed to set watchdog timeout (err = %d)\n",
154			ret);
155	else
156		wdd->timeout = wdt_timeout[da9063_wdt_timeout_to_sel(timeout)];
157
158	return ret;
159}
160
161static int da9063_wdt_restart(struct watchdog_device *wdd, unsigned long action,
162			      void *data)
163{
164	struct da9063 *da9063 = watchdog_get_drvdata(wdd);
165	int ret;
166
167	ret = regmap_write(da9063->regmap, DA9063_REG_CONTROL_F,
168			   DA9063_SHUTDOWN);
169	if (ret)
170		dev_alert(da9063->dev, "Failed to shutdown (err = %d)\n",
171			  ret);
172
173	return ret;
174}
175
176static const struct watchdog_info da9063_watchdog_info = {
177	.options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING,
178	.identity = "DA9063 Watchdog",
179};
180
181static const struct watchdog_ops da9063_watchdog_ops = {
182	.owner = THIS_MODULE,
183	.start = da9063_wdt_start,
184	.stop = da9063_wdt_stop,
185	.ping = da9063_wdt_ping,
186	.set_timeout = da9063_wdt_set_timeout,
187	.restart = da9063_wdt_restart,
188};
189
190static int da9063_wdt_probe(struct platform_device *pdev)
191{
192	struct device *dev = &pdev->dev;
193	struct da9063 *da9063;
194	struct watchdog_device *wdd;
195	unsigned int timeout;
196
197	if (!dev->parent)
198		return -EINVAL;
199
200	da9063 = dev_get_drvdata(dev->parent);
201	if (!da9063)
202		return -EINVAL;
203
204	wdd = devm_kzalloc(dev, sizeof(*wdd), GFP_KERNEL);
205	if (!wdd)
206		return -ENOMEM;
207
208	wdd->info = &da9063_watchdog_info;
209	wdd->ops = &da9063_watchdog_ops;
210	wdd->min_timeout = DA9063_WDT_MIN_TIMEOUT;
211	wdd->max_timeout = DA9063_WDT_MAX_TIMEOUT;
212	wdd->min_hw_heartbeat_ms = DA9063_RESET_PROTECTION_MS;
213	wdd->parent = dev;
214	wdd->status = WATCHDOG_NOWAYOUT_INIT_STATUS;
215
216	watchdog_set_restart_priority(wdd, 128);
217	watchdog_set_drvdata(wdd, da9063);
218
219	wdd->timeout = DA9063_WDG_TIMEOUT;
220
221	/* Use pre-configured timeout if watchdog is already running. */
222	timeout = da9063_wdt_read_timeout(da9063);
223	if (timeout)
224		wdd->timeout = timeout;
225
226	/* Set timeout, maybe override it with DT value, scale it */
227	watchdog_init_timeout(wdd, 0, dev);
228	da9063_wdt_set_timeout(wdd, wdd->timeout);
229
230	/* Update timeout if the watchdog is already running. */
231	if (timeout) {
232		da9063_wdt_update_timeout(da9063, wdd->timeout);
233		set_bit(WDOG_HW_RUNNING, &wdd->status);
234	}
235
236	return devm_watchdog_register_device(dev, wdd);
237}
238
239static struct platform_driver da9063_wdt_driver = {
240	.probe = da9063_wdt_probe,
241	.driver = {
242		.name = DA9063_DRVNAME_WATCHDOG,
243	},
244};
245module_platform_driver(da9063_wdt_driver);
246
247MODULE_AUTHOR("Mariusz Wojtasik <mariusz.wojtasik@diasemi.com>");
248MODULE_DESCRIPTION("Watchdog driver for Dialog DA9063");
249MODULE_LICENSE("GPL");
250MODULE_ALIAS("platform:" DA9063_DRVNAME_WATCHDOG);