1/*
2 * System monitoring driver for DA9055 PMICs.
3 *
4 * Copyright(c) 2012 Dialog Semiconductor Ltd.
5 *
6 * Author: David Dajun Chen <dchen@diasemi.com>
7 *
8 * This program is free software; you can redistribute it and/or modify
9 * it under the terms of the GNU General Public License as published by
10 * the Free Software Foundation; either version 2 of the License, or
11 * (at your option) any later version.
12 *
13 */
14
15#include <linux/module.h>
16#include <linux/types.h>
17#include <linux/kernel.h>
18#include <linux/slab.h>
19#include <linux/platform_device.h>
20#include <linux/watchdog.h>
21#include <linux/delay.h>
22
23#include <linux/mfd/da9055/core.h>
24#include <linux/mfd/da9055/reg.h>
25
26static bool nowayout = WATCHDOG_NOWAYOUT;
27module_param(nowayout, bool, 0);
28MODULE_PARM_DESC(nowayout,
29		 "Watchdog cannot be stopped once started (default="
30		 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
31
32#define DA9055_DEF_TIMEOUT	4
33#define DA9055_TWDMIN		256
34
35struct da9055_wdt_data {
36	struct watchdog_device wdt;
37	struct da9055 *da9055;
38	struct kref kref;
39};
40
41static const struct {
42	u8 reg_val;
43	int user_time;  /* In seconds */
44} da9055_wdt_maps[] = {
45	{ 0, 0 },
46	{ 1, 2 },
47	{ 2, 4 },
48	{ 3, 8 },
49	{ 4, 16 },
50	{ 5, 32 },
51	{ 5, 33 },  /* Actual time  32.768s so included both 32s and 33s */
52	{ 6, 65 },
53	{ 6, 66 },  /* Actual time 65.536s so include both, 65s and 66s */
54	{ 7, 131 },
55};
56
57static int da9055_wdt_set_timeout(struct watchdog_device *wdt_dev,
58				  unsigned int timeout)
59{
60	struct da9055_wdt_data *driver_data = watchdog_get_drvdata(wdt_dev);
61	struct da9055 *da9055 = driver_data->da9055;
62	int ret, i;
63
64	for (i = 0; i < ARRAY_SIZE(da9055_wdt_maps); i++)
65		if (da9055_wdt_maps[i].user_time == timeout)
66			break;
67
68	if (i == ARRAY_SIZE(da9055_wdt_maps))
69		ret = -EINVAL;
70	else
71		ret = da9055_reg_update(da9055, DA9055_REG_CONTROL_B,
72					DA9055_TWDSCALE_MASK,
73					da9055_wdt_maps[i].reg_val <<
74					DA9055_TWDSCALE_SHIFT);
75	if (ret < 0) {
76		dev_err(da9055->dev,
77			"Failed to update timescale bit, %d\n", ret);
78		return ret;
79	}
80
81	wdt_dev->timeout = timeout;
82
83	return 0;
84}
85
86static int da9055_wdt_ping(struct watchdog_device *wdt_dev)
87{
88	struct da9055_wdt_data *driver_data = watchdog_get_drvdata(wdt_dev);
89	struct da9055 *da9055 = driver_data->da9055;
90
91	/*
92	 * We have a minimum time for watchdog window called TWDMIN. A write
93	 * to the watchdog before this elapsed time will cause an error.
94	 */
95	mdelay(DA9055_TWDMIN);
96
97	/* Reset the watchdog timer */
98	return da9055_reg_update(da9055, DA9055_REG_CONTROL_E,
99				 DA9055_WATCHDOG_MASK, 1);
100}
101
102static void da9055_wdt_release_resources(struct kref *r)
103{
104}
105
106static void da9055_wdt_ref(struct watchdog_device *wdt_dev)
107{
108	struct da9055_wdt_data *driver_data = watchdog_get_drvdata(wdt_dev);
109
110	kref_get(&driver_data->kref);
111}
112
113static void da9055_wdt_unref(struct watchdog_device *wdt_dev)
114{
115	struct da9055_wdt_data *driver_data = watchdog_get_drvdata(wdt_dev);
116
117	kref_put(&driver_data->kref, da9055_wdt_release_resources);
118}
119
120static int da9055_wdt_start(struct watchdog_device *wdt_dev)
121{
122	return da9055_wdt_set_timeout(wdt_dev, wdt_dev->timeout);
123}
124
125static int da9055_wdt_stop(struct watchdog_device *wdt_dev)
126{
127	return da9055_wdt_set_timeout(wdt_dev, 0);
128}
129
130static struct watchdog_info da9055_wdt_info = {
131	.options	= WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING,
132	.identity	= "DA9055 Watchdog",
133};
134
135static const struct watchdog_ops da9055_wdt_ops = {
136	.owner = THIS_MODULE,
137	.start = da9055_wdt_start,
138	.stop = da9055_wdt_stop,
139	.ping = da9055_wdt_ping,
140	.set_timeout = da9055_wdt_set_timeout,
141	.ref = da9055_wdt_ref,
142	.unref = da9055_wdt_unref,
143};
144
145static int da9055_wdt_probe(struct platform_device *pdev)
146{
147	struct da9055 *da9055 = dev_get_drvdata(pdev->dev.parent);
148	struct da9055_wdt_data *driver_data;
149	struct watchdog_device *da9055_wdt;
150	int ret;
151
152	driver_data = devm_kzalloc(&pdev->dev, sizeof(*driver_data),
153				   GFP_KERNEL);
154	if (!driver_data)
155		return -ENOMEM;
156
157	driver_data->da9055 = da9055;
158
159	da9055_wdt = &driver_data->wdt;
160
161	da9055_wdt->timeout = DA9055_DEF_TIMEOUT;
162	da9055_wdt->info = &da9055_wdt_info;
163	da9055_wdt->ops = &da9055_wdt_ops;
164	watchdog_set_nowayout(da9055_wdt, nowayout);
165	watchdog_set_drvdata(da9055_wdt, driver_data);
166
167	kref_init(&driver_data->kref);
168
169	ret = da9055_wdt_stop(da9055_wdt);
170	if (ret < 0) {
171		dev_err(&pdev->dev, "Failed to stop watchdog, %d\n", ret);
172		goto err;
173	}
174
175	platform_set_drvdata(pdev, driver_data);
176
177	ret = watchdog_register_device(&driver_data->wdt);
178	if (ret != 0)
179		dev_err(da9055->dev, "watchdog_register_device() failed: %d\n",
180			ret);
181
182err:
183	return ret;
184}
185
186static int da9055_wdt_remove(struct platform_device *pdev)
187{
188	struct da9055_wdt_data *driver_data = platform_get_drvdata(pdev);
189
190	watchdog_unregister_device(&driver_data->wdt);
191	kref_put(&driver_data->kref, da9055_wdt_release_resources);
192
193	return 0;
194}
195
196static struct platform_driver da9055_wdt_driver = {
197	.probe = da9055_wdt_probe,
198	.remove = da9055_wdt_remove,
199	.driver = {
200		.name	= "da9055-watchdog",
201	},
202};
203
204module_platform_driver(da9055_wdt_driver);
205
206MODULE_AUTHOR("David Dajun Chen <dchen@diasemi.com>");
207MODULE_DESCRIPTION("DA9055 watchdog");
208MODULE_LICENSE("GPL");
209MODULE_ALIAS("platform:da9055-watchdog");
210