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Merge branch 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel...
[karo-tx-linux.git] / drivers / watchdog / ts4800_wdt.c
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
59 static void ts4800_write_feed(struct ts4800_wdt *wdt, u32 val)
60 {
61         regmap_write(wdt->regmap, wdt->feed_offset, val);
62 }
63
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
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
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
109 static int ts4800_wdt_probe(struct platform_device *pdev)
110 {
111         struct device_node *np = pdev->dev.of_node;
112         struct device_node *syscon_np;
113         struct watchdog_device *wdd;
114         struct ts4800_wdt *wdt;
115         u32 reg;
116         int ret;
117
118         syscon_np = of_parse_phandle(np, "syscon", 0);
119         if (!syscon_np) {
120                 dev_err(&pdev->dev, "no syscon property\n");
121                 return -ENODEV;
122         }
123
124         ret = of_property_read_u32_index(np, "syscon", 1, &reg);
125         if (ret < 0) {
126                 dev_err(&pdev->dev, "no offset in syscon\n");
127                 return ret;
128         }
129
130         /* allocate memory for watchdog struct */
131         wdt = devm_kzalloc(&pdev->dev, sizeof(*wdt), GFP_KERNEL);
132         if (!wdt)
133                 return -ENOMEM;
134
135         /* set regmap and offset to know where to write */
136         wdt->feed_offset = reg;
137         wdt->regmap = syscon_node_to_regmap(syscon_np);
138         if (IS_ERR(wdt->regmap)) {
139                 dev_err(&pdev->dev, "cannot get parent's regmap\n");
140                 return PTR_ERR(wdt->regmap);
141         }
142
143         /* Initialize struct watchdog_device */
144         wdd = &wdt->wdd;
145         wdd->parent = &pdev->dev;
146         wdd->info = &ts4800_wdt_info;
147         wdd->ops = &ts4800_wdt_ops;
148         wdd->min_timeout = ts4800_wdt_map[0].timeout;
149         wdd->max_timeout = ts4800_wdt_map[MAX_TIMEOUT_INDEX].timeout;
150
151         watchdog_set_drvdata(wdd, wdt);
152         watchdog_set_nowayout(wdd, nowayout);
153         watchdog_init_timeout(wdd, 0, &pdev->dev);
154
155         /*
156          * As this watchdog supports only a few values, ts4800_wdt_set_timeout
157          * must be called to initialize timeout and feed_val with valid values.
158          * Default to maximum timeout if none, or an invalid one, is provided in
159          * device tree.
160          */
161         if (!wdd->timeout)
162                 wdd->timeout = wdd->max_timeout;
163         ts4800_wdt_set_timeout(wdd, wdd->timeout);
164
165         /*
166          * The feed register is write-only, so it is not possible to determine
167          * watchdog's state. Disable it to be in a known state.
168          */
169         ts4800_wdt_stop(wdd);
170
171         ret = watchdog_register_device(wdd);
172         if (ret) {
173                 dev_err(&pdev->dev,
174                         "failed to register watchdog device\n");
175                 return ret;
176         }
177
178         platform_set_drvdata(pdev, wdt);
179
180         dev_info(&pdev->dev,
181                  "initialized (timeout = %d sec, nowayout = %d)\n",
182                  wdd->timeout, nowayout);
183
184         return 0;
185 }
186
187 static int ts4800_wdt_remove(struct platform_device *pdev)
188 {
189         struct ts4800_wdt *wdt = platform_get_drvdata(pdev);
190
191         watchdog_unregister_device(&wdt->wdd);
192
193         return 0;
194 }
195
196 static const struct of_device_id ts4800_wdt_of_match[] = {
197         { .compatible = "technologic,ts4800-wdt", },
198         { },
199 };
200 MODULE_DEVICE_TABLE(of, ts4800_wdt_of_match);
201
202 static struct platform_driver ts4800_wdt_driver = {
203         .probe          = ts4800_wdt_probe,
204         .remove         = ts4800_wdt_remove,
205         .driver         = {
206                 .name   = "ts4800_wdt",
207                 .of_match_table = ts4800_wdt_of_match,
208         },
209 };
210
211 module_platform_driver(ts4800_wdt_driver);
212
213 MODULE_AUTHOR("Damien Riegel <damien.riegel@savoirfairelinux.com>");
214 MODULE_LICENSE("GPL v2");
215 MODULE_ALIAS("platform:ts4800_wdt");