1/*
2 * System monitoring driver for DA9052 PMICs.
3 *
4 * Copyright(c) 2012 Dialog Semiconductor Ltd.
5 *
6 * Author: Anthony Olech <Anthony.Olech@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/delay.h>
17#include <linux/uaccess.h>
18#include <linux/platform_device.h>
19#include <linux/time.h>
20#include <linux/watchdog.h>
21#include <linux/types.h>
22#include <linux/kernel.h>
23#include <linux/jiffies.h>
24
25#include <linux/mfd/da9052/reg.h>
26#include <linux/mfd/da9052/da9052.h>
27
28#define DA9052_DEF_TIMEOUT	4
29#define DA9052_TWDMIN		256
30
31struct da9052_wdt_data {
32	struct watchdog_device wdt;
33	struct da9052 *da9052;
34	struct kref kref;
35	unsigned long jpast;
36};
37
38static const struct {
39	u8 reg_val;
40	int time;  /* Seconds */
41} da9052_wdt_maps[] = {
42	{ 1, 2 },
43	{ 2, 4 },
44	{ 3, 8 },
45	{ 4, 16 },
46	{ 5, 32 },
47	{ 5, 33 },  /* Actual time  32.768s so included both 32s and 33s */
48	{ 6, 65 },
49	{ 6, 66 },  /* Actual time 65.536s so include both, 65s and 66s */
50	{ 7, 131 },
51};
52
53
54static void da9052_wdt_release_resources(struct kref *r)
55{
56}
57
58static int da9052_wdt_set_timeout(struct watchdog_device *wdt_dev,
59				  unsigned int timeout)
60{
61	struct da9052_wdt_data *driver_data = watchdog_get_drvdata(wdt_dev);
62	struct da9052 *da9052 = driver_data->da9052;
63	int ret, i;
64
65	/*
66	 * Disable the Watchdog timer before setting
67	 * new time out.
68	 */
69	ret = da9052_reg_update(da9052, DA9052_CONTROL_D_REG,
70				DA9052_CONTROLD_TWDSCALE, 0);
71	if (ret < 0) {
72		dev_err(da9052->dev, "Failed to disable watchdog bit, %d\n",
73			ret);
74		return ret;
75	}
76	if (timeout) {
77		/*
78		 * To change the timeout, da9052 needs to
79		 * be disabled for at least 150 us.
80		 */
81		udelay(150);
82
83		/* Set the desired timeout */
84		for (i = 0; i < ARRAY_SIZE(da9052_wdt_maps); i++)
85			if (da9052_wdt_maps[i].time == timeout)
86				break;
87
88		if (i == ARRAY_SIZE(da9052_wdt_maps))
89			ret = -EINVAL;
90		else
91			ret = da9052_reg_update(da9052, DA9052_CONTROL_D_REG,
92						DA9052_CONTROLD_TWDSCALE,
93						da9052_wdt_maps[i].reg_val);
94		if (ret < 0) {
95			dev_err(da9052->dev,
96				"Failed to update timescale bit, %d\n", ret);
97			return ret;
98		}
99
100		wdt_dev->timeout = timeout;
101		driver_data->jpast = jiffies;
102	}
103
104	return 0;
105}
106
107static void da9052_wdt_ref(struct watchdog_device *wdt_dev)
108{
109	struct da9052_wdt_data *driver_data = watchdog_get_drvdata(wdt_dev);
110
111	kref_get(&driver_data->kref);
112}
113
114static void da9052_wdt_unref(struct watchdog_device *wdt_dev)
115{
116	struct da9052_wdt_data *driver_data = watchdog_get_drvdata(wdt_dev);
117
118	kref_put(&driver_data->kref, da9052_wdt_release_resources);
119}
120
121static int da9052_wdt_start(struct watchdog_device *wdt_dev)
122{
123	return da9052_wdt_set_timeout(wdt_dev, wdt_dev->timeout);
124}
125
126static int da9052_wdt_stop(struct watchdog_device *wdt_dev)
127{
128	return da9052_wdt_set_timeout(wdt_dev, 0);
129}
130
131static int da9052_wdt_ping(struct watchdog_device *wdt_dev)
132{
133	struct da9052_wdt_data *driver_data = watchdog_get_drvdata(wdt_dev);
134	struct da9052 *da9052 = driver_data->da9052;
135	unsigned long msec, jnow = jiffies;
136	int ret;
137
138	/*
139	 * We have a minimum time for watchdog window called TWDMIN. A write
140	 * to the watchdog before this elapsed time should cause an error.
141	 */
142	msec = (jnow - driver_data->jpast) * 1000/HZ;
143	if (msec < DA9052_TWDMIN)
144		mdelay(msec);
145
146	/* Reset the watchdog timer */
147	ret = da9052_reg_update(da9052, DA9052_CONTROL_D_REG,
148				DA9052_CONTROLD_WATCHDOG, 1 << 7);
149	if (ret < 0)
150		goto err_strobe;
151
152	/*
153	 * FIXME: Reset the watchdog core, in general PMIC
154	 * is supposed to do this
155	 */
156	ret = da9052_reg_update(da9052, DA9052_CONTROL_D_REG,
157				DA9052_CONTROLD_WATCHDOG, 0 << 7);
158err_strobe:
159	return ret;
160}
161
162static struct watchdog_info da9052_wdt_info = {
163	.options	= WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING,
164	.identity	= "DA9052 Watchdog",
165};
166
167static const struct watchdog_ops da9052_wdt_ops = {
168	.owner = THIS_MODULE,
169	.start = da9052_wdt_start,
170	.stop = da9052_wdt_stop,
171	.ping = da9052_wdt_ping,
172	.set_timeout = da9052_wdt_set_timeout,
173	.ref = da9052_wdt_ref,
174	.unref = da9052_wdt_unref,
175};
176
177
178static int da9052_wdt_probe(struct platform_device *pdev)
179{
180	struct da9052 *da9052 = dev_get_drvdata(pdev->dev.parent);
181	struct da9052_wdt_data *driver_data;
182	struct watchdog_device *da9052_wdt;
183	int ret;
184
185	driver_data = devm_kzalloc(&pdev->dev, sizeof(*driver_data),
186				   GFP_KERNEL);
187	if (!driver_data) {
188		ret = -ENOMEM;
189		goto err;
190	}
191	driver_data->da9052 = da9052;
192
193	da9052_wdt = &driver_data->wdt;
194
195	da9052_wdt->timeout = DA9052_DEF_TIMEOUT;
196	da9052_wdt->info = &da9052_wdt_info;
197	da9052_wdt->ops = &da9052_wdt_ops;
198	watchdog_set_drvdata(da9052_wdt, driver_data);
199
200	kref_init(&driver_data->kref);
201
202	ret = da9052_reg_update(da9052, DA9052_CONTROL_D_REG,
203				DA9052_CONTROLD_TWDSCALE, 0);
204	if (ret < 0) {
205		dev_err(&pdev->dev, "Failed to disable watchdog bits, %d\n",
206			ret);
207		goto err;
208	}
209
210	ret = watchdog_register_device(&driver_data->wdt);
211	if (ret != 0) {
212		dev_err(da9052->dev, "watchdog_register_device() failed: %d\n",
213			ret);
214		goto err;
215	}
216
217	platform_set_drvdata(pdev, driver_data);
218err:
219	return ret;
220}
221
222static int da9052_wdt_remove(struct platform_device *pdev)
223{
224	struct da9052_wdt_data *driver_data = platform_get_drvdata(pdev);
225
226	watchdog_unregister_device(&driver_data->wdt);
227	kref_put(&driver_data->kref, da9052_wdt_release_resources);
228
229	return 0;
230}
231
232static struct platform_driver da9052_wdt_driver = {
233	.probe = da9052_wdt_probe,
234	.remove = da9052_wdt_remove,
235	.driver = {
236		.name	= "da9052-watchdog",
237	},
238};
239
240module_platform_driver(da9052_wdt_driver);
241
242MODULE_AUTHOR("Anthony Olech <Anthony.Olech@diasemi.com>");
243MODULE_DESCRIPTION("DA9052 SM Device Driver");
244MODULE_LICENSE("GPL");
245MODULE_ALIAS("platform:da9052-watchdog");
246