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 };
30static 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
40static 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 */
56static 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
65static 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
72static int
73da9063_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
97static 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
110static 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
123static 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
144static 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
172static 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
201static const struct watchdog_info da9063_watchdog_info = {
202	.options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING,
203	.identity = "DA9063 Watchdog",
204};
205
206static 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
215static 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
267static 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
280static 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
293static SIMPLE_DEV_PM_OPS(da9063_wdt_pm_ops,
294			da9063_wdt_suspend, da9063_wdt_resume);
295
296static 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};
303module_platform_driver(da9063_wdt_driver);
304
305MODULE_AUTHOR("Mariusz Wojtasik <mariusz.wojtasik@diasemi.com>");
306MODULE_DESCRIPTION("Watchdog driver for Dialog DA9063");
307MODULE_LICENSE("GPL");
308MODULE_ALIAS("platform:" DA9063_DRVNAME_WATCHDOG);
309