summaryrefslogtreecommitdiff
path: root/drivers/watchdog/ts4800_wdt.c
blob: 24b1ad52102e81de3287d2a9a0b1bfb2ca99faef (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
// SPDX-License-Identifier: GPL-2.0-only
/*
 * Watchdog driver for TS-4800 based boards
 *
 * Copyright (c) 2015 - Savoir-faire Linux
 *
 */

#include <linux/kernel.h>
#include <linux/mfd/syscon.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/platform_device.h>
#include <linux/regmap.h>
#include <linux/watchdog.h>

static bool nowayout = WATCHDOG_NOWAYOUT;
module_param(nowayout, bool, 0);
MODULE_PARM_DESC(nowayout,
	"Watchdog cannot be stopped once started (default="
	__MODULE_STRING(WATCHDOG_NOWAYOUT) ")");

/* possible feed values */
#define TS4800_WDT_FEED_2S       0x1
#define TS4800_WDT_FEED_10S      0x2
#define TS4800_WDT_DISABLE       0x3

struct ts4800_wdt {
	struct watchdog_device  wdd;
	struct regmap           *regmap;
	u32                     feed_offset;
	u32                     feed_val;
};

/*
 * TS-4800 supports the following timeout values:
 *
 *   value desc
 *   ---------------------
 *     0    feed for 338ms
 *     1    feed for 2.706s
 *     2    feed for 10.824s
 *     3    disable watchdog
 *
 * Keep the regmap/timeout map ordered by timeout
 */
static const struct {
	const int timeout;
	const int regval;
} ts4800_wdt_map[] = {
	{ 2,  TS4800_WDT_FEED_2S },
	{ 10, TS4800_WDT_FEED_10S },
};

#define MAX_TIMEOUT_INDEX       (ARRAY_SIZE(ts4800_wdt_map) - 1)

static void ts4800_write_feed(struct ts4800_wdt *wdt, u32 val)
{
	regmap_write(wdt->regmap, wdt->feed_offset, val);
}

static int ts4800_wdt_start(struct watchdog_device *wdd)
{
	struct ts4800_wdt *wdt = watchdog_get_drvdata(wdd);

	ts4800_write_feed(wdt, wdt->feed_val);
	return 0;
}

static int ts4800_wdt_stop(struct watchdog_device *wdd)
{
	struct ts4800_wdt *wdt = watchdog_get_drvdata(wdd);

	ts4800_write_feed(wdt, TS4800_WDT_DISABLE);
	return 0;
}

static int ts4800_wdt_set_timeout(struct watchdog_device *wdd,
				  unsigned int timeout)
{
	struct ts4800_wdt *wdt = watchdog_get_drvdata(wdd);
	int i;

	for (i = 0; i < MAX_TIMEOUT_INDEX; i++) {
		if (ts4800_wdt_map[i].timeout >= timeout)
			break;
	}

	wdd->timeout = ts4800_wdt_map[i].timeout;
	wdt->feed_val = ts4800_wdt_map[i].regval;

	return 0;
}

static const struct watchdog_ops ts4800_wdt_ops = {
	.owner = THIS_MODULE,
	.start = ts4800_wdt_start,
	.stop = ts4800_wdt_stop,
	.set_timeout = ts4800_wdt_set_timeout,
};

static const struct watchdog_info ts4800_wdt_info = {
	.options = WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE | WDIOF_KEEPALIVEPING,
	.identity = "TS-4800 Watchdog",
};

static int ts4800_wdt_probe(struct platform_device *pdev)
{
	struct device *dev = &pdev->dev;
	struct device_node *np = dev->of_node;
	struct device_node *syscon_np;
	struct watchdog_device *wdd;
	struct ts4800_wdt *wdt;
	u32 reg;
	int ret;

	syscon_np = of_parse_phandle(np, "syscon", 0);
	if (!syscon_np) {
		dev_err(dev, "no syscon property\n");
		return -ENODEV;
	}

	ret = of_property_read_u32_index(np, "syscon", 1, &reg);
	if (ret < 0) {
		dev_err(dev, "no offset in syscon\n");
		of_node_put(syscon_np);
		return ret;
	}

	/* allocate memory for watchdog struct */
	wdt = devm_kzalloc(dev, sizeof(*wdt), GFP_KERNEL);
	if (!wdt) {
		of_node_put(syscon_np);
		return -ENOMEM;
	}

	/* set regmap and offset to know where to write */
	wdt->feed_offset = reg;
	wdt->regmap = syscon_node_to_regmap(syscon_np);
	of_node_put(syscon_np);
	if (IS_ERR(wdt->regmap)) {
		dev_err(dev, "cannot get parent's regmap\n");
		return PTR_ERR(wdt->regmap);
	}

	/* Initialize struct watchdog_device */
	wdd = &wdt->wdd;
	wdd->parent = dev;
	wdd->info = &ts4800_wdt_info;
	wdd->ops = &ts4800_wdt_ops;
	wdd->min_timeout = ts4800_wdt_map[0].timeout;
	wdd->max_timeout = ts4800_wdt_map[MAX_TIMEOUT_INDEX].timeout;

	watchdog_set_drvdata(wdd, wdt);
	watchdog_set_nowayout(wdd, nowayout);
	watchdog_init_timeout(wdd, 0, dev);

	/*
	 * As this watchdog supports only a few values, ts4800_wdt_set_timeout
	 * must be called to initialize timeout and feed_val with valid values.
	 * Default to maximum timeout if none, or an invalid one, is provided in
	 * device tree.
	 */
	if (!wdd->timeout)
		wdd->timeout = wdd->max_timeout;
	ts4800_wdt_set_timeout(wdd, wdd->timeout);

	/*
	 * The feed register is write-only, so it is not possible to determine
	 * watchdog's state. Disable it to be in a known state.
	 */
	ts4800_wdt_stop(wdd);

	ret = devm_watchdog_register_device(dev, wdd);
	if (ret)
		return ret;

	platform_set_drvdata(pdev, wdt);

	dev_info(dev, "initialized (timeout = %d sec, nowayout = %d)\n",
		 wdd->timeout, nowayout);

	return 0;
}

static const struct of_device_id ts4800_wdt_of_match[] = {
	{ .compatible = "technologic,ts4800-wdt", },
	{ },
};
MODULE_DEVICE_TABLE(of, ts4800_wdt_of_match);

static struct platform_driver ts4800_wdt_driver = {
	.probe		= ts4800_wdt_probe,
	.driver		= {
		.name	= "ts4800_wdt",
		.of_match_table = ts4800_wdt_of_match,
	},
};

module_platform_driver(ts4800_wdt_driver);

MODULE_AUTHOR("Damien Riegel <damien.riegel@savoirfairelinux.com>");
MODULE_DESCRIPTION("Watchdog driver for TS-4800 based boards");
MODULE_LICENSE("GPL v2");
MODULE_ALIAS("platform:ts4800_wdt");