xref: /linux/drivers/watchdog/ts4800_wdt.c (revision 327fceff3b634e6f21bbe60bd1d28e41d5b1d924)
1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * Watchdog driver for TS-4800 based boards
4  *
5  * Copyright (c) 2015 - Savoir-faire Linux
6  *
7  */
8 
9 #include <linux/kernel.h>
10 #include <linux/mfd/syscon.h>
11 #include <linux/module.h>
12 #include <linux/of.h>
13 #include <linux/platform_device.h>
14 #include <linux/regmap.h>
15 #include <linux/watchdog.h>
16 
17 static bool nowayout = WATCHDOG_NOWAYOUT;
18 module_param(nowayout, bool, 0);
19 MODULE_PARM_DESC(nowayout,
20 	"Watchdog cannot be stopped once started (default="
21 	__MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
22 
23 /* possible feed values */
24 #define TS4800_WDT_FEED_2S       0x1
25 #define TS4800_WDT_FEED_10S      0x2
26 #define TS4800_WDT_DISABLE       0x3
27 
28 struct ts4800_wdt {
29 	struct watchdog_device  wdd;
30 	struct regmap           *regmap;
31 	u32                     feed_offset;
32 	u32                     feed_val;
33 };
34 
35 /*
36  * TS-4800 supports the following timeout values:
37  *
38  *   value desc
39  *   ---------------------
40  *     0    feed for 338ms
41  *     1    feed for 2.706s
42  *     2    feed for 10.824s
43  *     3    disable watchdog
44  *
45  * Keep the regmap/timeout map ordered by timeout
46  */
47 static const struct {
48 	const int timeout;
49 	const int regval;
50 } ts4800_wdt_map[] = {
51 	{ 2,  TS4800_WDT_FEED_2S },
52 	{ 10, TS4800_WDT_FEED_10S },
53 };
54 
55 #define MAX_TIMEOUT_INDEX       (ARRAY_SIZE(ts4800_wdt_map) - 1)
56 
ts4800_write_feed(struct ts4800_wdt * wdt,u32 val)57 static void ts4800_write_feed(struct ts4800_wdt *wdt, u32 val)
58 {
59 	regmap_write(wdt->regmap, wdt->feed_offset, val);
60 }
61 
ts4800_wdt_start(struct watchdog_device * wdd)62 static int ts4800_wdt_start(struct watchdog_device *wdd)
63 {
64 	struct ts4800_wdt *wdt = watchdog_get_drvdata(wdd);
65 
66 	ts4800_write_feed(wdt, wdt->feed_val);
67 	return 0;
68 }
69 
ts4800_wdt_stop(struct watchdog_device * wdd)70 static int ts4800_wdt_stop(struct watchdog_device *wdd)
71 {
72 	struct ts4800_wdt *wdt = watchdog_get_drvdata(wdd);
73 
74 	ts4800_write_feed(wdt, TS4800_WDT_DISABLE);
75 	return 0;
76 }
77 
ts4800_wdt_set_timeout(struct watchdog_device * wdd,unsigned int timeout)78 static int ts4800_wdt_set_timeout(struct watchdog_device *wdd,
79 				  unsigned int timeout)
80 {
81 	struct ts4800_wdt *wdt = watchdog_get_drvdata(wdd);
82 	int i;
83 
84 	for (i = 0; i < MAX_TIMEOUT_INDEX; i++) {
85 		if (ts4800_wdt_map[i].timeout >= timeout)
86 			break;
87 	}
88 
89 	wdd->timeout = ts4800_wdt_map[i].timeout;
90 	wdt->feed_val = ts4800_wdt_map[i].regval;
91 
92 	return 0;
93 }
94 
95 static const struct watchdog_ops ts4800_wdt_ops = {
96 	.owner = THIS_MODULE,
97 	.start = ts4800_wdt_start,
98 	.stop = ts4800_wdt_stop,
99 	.set_timeout = ts4800_wdt_set_timeout,
100 };
101 
102 static const struct watchdog_info ts4800_wdt_info = {
103 	.options = WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE | WDIOF_KEEPALIVEPING,
104 	.identity = "TS-4800 Watchdog",
105 };
106 
ts4800_wdt_probe(struct platform_device * pdev)107 static int ts4800_wdt_probe(struct platform_device *pdev)
108 {
109 	struct device *dev = &pdev->dev;
110 	struct device_node *np = dev->of_node;
111 	struct device_node *syscon_np;
112 	struct watchdog_device *wdd;
113 	struct ts4800_wdt *wdt;
114 	u32 reg;
115 	int ret;
116 
117 	syscon_np = of_parse_phandle(np, "syscon", 0);
118 	if (!syscon_np) {
119 		dev_err(dev, "no syscon property\n");
120 		return -ENODEV;
121 	}
122 
123 	ret = of_property_read_u32_index(np, "syscon", 1, &reg);
124 	if (ret < 0) {
125 		dev_err(dev, "no offset in syscon\n");
126 		of_node_put(syscon_np);
127 		return ret;
128 	}
129 
130 	/* allocate memory for watchdog struct */
131 	wdt = devm_kzalloc(dev, sizeof(*wdt), GFP_KERNEL);
132 	if (!wdt) {
133 		of_node_put(syscon_np);
134 		return -ENOMEM;
135 	}
136 
137 	/* set regmap and offset to know where to write */
138 	wdt->feed_offset = reg;
139 	wdt->regmap = syscon_node_to_regmap(syscon_np);
140 	of_node_put(syscon_np);
141 	if (IS_ERR(wdt->regmap)) {
142 		dev_err(dev, "cannot get parent's regmap\n");
143 		return PTR_ERR(wdt->regmap);
144 	}
145 
146 	/* Initialize struct watchdog_device */
147 	wdd = &wdt->wdd;
148 	wdd->parent = dev;
149 	wdd->info = &ts4800_wdt_info;
150 	wdd->ops = &ts4800_wdt_ops;
151 	wdd->min_timeout = ts4800_wdt_map[0].timeout;
152 	wdd->max_timeout = ts4800_wdt_map[MAX_TIMEOUT_INDEX].timeout;
153 
154 	watchdog_set_drvdata(wdd, wdt);
155 	watchdog_set_nowayout(wdd, nowayout);
156 	watchdog_init_timeout(wdd, 0, dev);
157 
158 	/*
159 	 * As this watchdog supports only a few values, ts4800_wdt_set_timeout
160 	 * must be called to initialize timeout and feed_val with valid values.
161 	 * Default to maximum timeout if none, or an invalid one, is provided in
162 	 * device tree.
163 	 */
164 	if (!wdd->timeout)
165 		wdd->timeout = wdd->max_timeout;
166 	ts4800_wdt_set_timeout(wdd, wdd->timeout);
167 
168 	/*
169 	 * The feed register is write-only, so it is not possible to determine
170 	 * watchdog's state. Disable it to be in a known state.
171 	 */
172 	ts4800_wdt_stop(wdd);
173 
174 	ret = devm_watchdog_register_device(dev, wdd);
175 	if (ret)
176 		return ret;
177 
178 	platform_set_drvdata(pdev, wdt);
179 
180 	dev_info(dev, "initialized (timeout = %d sec, nowayout = %d)\n",
181 		 wdd->timeout, nowayout);
182 
183 	return 0;
184 }
185 
186 static const struct of_device_id ts4800_wdt_of_match[] = {
187 	{ .compatible = "technologic,ts4800-wdt", },
188 	{ },
189 };
190 MODULE_DEVICE_TABLE(of, ts4800_wdt_of_match);
191 
192 static struct platform_driver ts4800_wdt_driver = {
193 	.probe		= ts4800_wdt_probe,
194 	.driver		= {
195 		.name	= "ts4800_wdt",
196 		.of_match_table = ts4800_wdt_of_match,
197 	},
198 };
199 
200 module_platform_driver(ts4800_wdt_driver);
201 
202 MODULE_AUTHOR("Damien Riegel <damien.riegel@savoirfairelinux.com>");
203 MODULE_DESCRIPTION("Watchdog driver for TS-4800 based boards");
204 MODULE_LICENSE("GPL v2");
205 MODULE_ALIAS("platform:ts4800_wdt");
206