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, ®);
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_LICENSE("GPL v2");
204 MODULE_ALIAS("platform:ts4800_wdt");
205