1 /*
2 * Watchdog driver for TS-4800 based boards
3 *
4 * Copyright (c) 2015 - Savoir-faire Linux
5 *
6 * This file is licensed under the terms of the GNU General Public
7 * License version 2. This program is licensed "as is" without any
8 * warranty of any kind, whether express or implied.
9 */
10
11 #include <linux/kernel.h>
12 #include <linux/mfd/syscon.h>
13 #include <linux/module.h>
14 #include <linux/of.h>
15 #include <linux/platform_device.h>
16 #include <linux/regmap.h>
17 #include <linux/watchdog.h>
18
19 static bool nowayout = WATCHDOG_NOWAYOUT;
20 module_param(nowayout, bool, 0);
21 MODULE_PARM_DESC(nowayout,
22 "Watchdog cannot be stopped once started (default="
23 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
24
25 /* possible feed values */
26 #define TS4800_WDT_FEED_2S 0x1
27 #define TS4800_WDT_FEED_10S 0x2
28 #define TS4800_WDT_DISABLE 0x3
29
30 struct ts4800_wdt {
31 struct watchdog_device wdd;
32 struct regmap *regmap;
33 u32 feed_offset;
34 u32 feed_val;
35 };
36
37 /*
38 * TS-4800 supports the following timeout values:
39 *
40 * value desc
41 * ---------------------
42 * 0 feed for 338ms
43 * 1 feed for 2.706s
44 * 2 feed for 10.824s
45 * 3 disable watchdog
46 *
47 * Keep the regmap/timeout map ordered by timeout
48 */
49 static const struct {
50 const int timeout;
51 const int regval;
52 } ts4800_wdt_map[] = {
53 { 2, TS4800_WDT_FEED_2S },
54 { 10, TS4800_WDT_FEED_10S },
55 };
56
57 #define MAX_TIMEOUT_INDEX (ARRAY_SIZE(ts4800_wdt_map) - 1)
58
ts4800_write_feed(struct ts4800_wdt * wdt,u32 val)59 static void ts4800_write_feed(struct ts4800_wdt *wdt, u32 val)
60 {
61 regmap_write(wdt->regmap, wdt->feed_offset, val);
62 }
63
ts4800_wdt_start(struct watchdog_device * wdd)64 static int ts4800_wdt_start(struct watchdog_device *wdd)
65 {
66 struct ts4800_wdt *wdt = watchdog_get_drvdata(wdd);
67
68 ts4800_write_feed(wdt, wdt->feed_val);
69 return 0;
70 }
71
ts4800_wdt_stop(struct watchdog_device * wdd)72 static int ts4800_wdt_stop(struct watchdog_device *wdd)
73 {
74 struct ts4800_wdt *wdt = watchdog_get_drvdata(wdd);
75
76 ts4800_write_feed(wdt, TS4800_WDT_DISABLE);
77 return 0;
78 }
79
ts4800_wdt_set_timeout(struct watchdog_device * wdd,unsigned int timeout)80 static int ts4800_wdt_set_timeout(struct watchdog_device *wdd,
81 unsigned int timeout)
82 {
83 struct ts4800_wdt *wdt = watchdog_get_drvdata(wdd);
84 int i;
85
86 for (i = 0; i < MAX_TIMEOUT_INDEX; i++) {
87 if (ts4800_wdt_map[i].timeout >= timeout)
88 break;
89 }
90
91 wdd->timeout = ts4800_wdt_map[i].timeout;
92 wdt->feed_val = ts4800_wdt_map[i].regval;
93
94 return 0;
95 }
96
97 static const struct watchdog_ops ts4800_wdt_ops = {
98 .owner = THIS_MODULE,
99 .start = ts4800_wdt_start,
100 .stop = ts4800_wdt_stop,
101 .set_timeout = ts4800_wdt_set_timeout,
102 };
103
104 static const struct watchdog_info ts4800_wdt_info = {
105 .options = WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE | WDIOF_KEEPALIVEPING,
106 .identity = "TS-4800 Watchdog",
107 };
108
ts4800_wdt_probe(struct platform_device * pdev)109 static int ts4800_wdt_probe(struct platform_device *pdev)
110 {
111 struct device *dev = &pdev->dev;
112 struct device_node *np = dev->of_node;
113 struct device_node *syscon_np;
114 struct watchdog_device *wdd;
115 struct ts4800_wdt *wdt;
116 u32 reg;
117 int ret;
118
119 syscon_np = of_parse_phandle(np, "syscon", 0);
120 if (!syscon_np) {
121 dev_err(dev, "no syscon property\n");
122 return -ENODEV;
123 }
124
125 ret = of_property_read_u32_index(np, "syscon", 1, ®);
126 if (ret < 0) {
127 dev_err(dev, "no offset in syscon\n");
128 return ret;
129 }
130
131 /* allocate memory for watchdog struct */
132 wdt = devm_kzalloc(dev, sizeof(*wdt), GFP_KERNEL);
133 if (!wdt)
134 return -ENOMEM;
135
136 /* set regmap and offset to know where to write */
137 wdt->feed_offset = reg;
138 wdt->regmap = syscon_node_to_regmap(syscon_np);
139 of_node_put(syscon_np);
140 if (IS_ERR(wdt->regmap)) {
141 dev_err(dev, "cannot get parent's regmap\n");
142 return PTR_ERR(wdt->regmap);
143 }
144
145 /* Initialize struct watchdog_device */
146 wdd = &wdt->wdd;
147 wdd->parent = dev;
148 wdd->info = &ts4800_wdt_info;
149 wdd->ops = &ts4800_wdt_ops;
150 wdd->min_timeout = ts4800_wdt_map[0].timeout;
151 wdd->max_timeout = ts4800_wdt_map[MAX_TIMEOUT_INDEX].timeout;
152
153 watchdog_set_drvdata(wdd, wdt);
154 watchdog_set_nowayout(wdd, nowayout);
155 watchdog_init_timeout(wdd, 0, dev);
156
157 /*
158 * As this watchdog supports only a few values, ts4800_wdt_set_timeout
159 * must be called to initialize timeout and feed_val with valid values.
160 * Default to maximum timeout if none, or an invalid one, is provided in
161 * device tree.
162 */
163 if (!wdd->timeout)
164 wdd->timeout = wdd->max_timeout;
165 ts4800_wdt_set_timeout(wdd, wdd->timeout);
166
167 /*
168 * The feed register is write-only, so it is not possible to determine
169 * watchdog's state. Disable it to be in a known state.
170 */
171 ts4800_wdt_stop(wdd);
172
173 ret = devm_watchdog_register_device(dev, wdd);
174 if (ret)
175 return ret;
176
177 platform_set_drvdata(pdev, wdt);
178
179 dev_info(dev, "initialized (timeout = %d sec, nowayout = %d)\n",
180 wdd->timeout, nowayout);
181
182 return 0;
183 }
184
185 static const struct of_device_id ts4800_wdt_of_match[] = {
186 { .compatible = "technologic,ts4800-wdt", },
187 { },
188 };
189 MODULE_DEVICE_TABLE(of, ts4800_wdt_of_match);
190
191 static struct platform_driver ts4800_wdt_driver = {
192 .probe = ts4800_wdt_probe,
193 .driver = {
194 .name = "ts4800_wdt",
195 .of_match_table = ts4800_wdt_of_match,
196 },
197 };
198
199 module_platform_driver(ts4800_wdt_driver);
200
201 MODULE_AUTHOR("Damien Riegel <damien.riegel@savoirfairelinux.com>");
202 MODULE_LICENSE("GPL v2");
203 MODULE_ALIAS("platform:ts4800_wdt");
204
