Merge tag 'v5.15.57' into rpi-5.15.y
[platform/kernel/linux-rpi.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 *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, &reg);
126         if (ret < 0) {
127                 dev_err(dev, "no offset in syscon\n");
128                 of_node_put(syscon_np);
129                 return ret;
130         }
131
132         /* allocate memory for watchdog struct */
133         wdt = devm_kzalloc(dev, sizeof(*wdt), GFP_KERNEL);
134         if (!wdt) {
135                 of_node_put(syscon_np);
136                 return -ENOMEM;
137         }
138
139         /* set regmap and offset to know where to write */
140         wdt->feed_offset = reg;
141         wdt->regmap = syscon_node_to_regmap(syscon_np);
142         of_node_put(syscon_np);
143         if (IS_ERR(wdt->regmap)) {
144                 dev_err(dev, "cannot get parent's regmap\n");
145                 return PTR_ERR(wdt->regmap);
146         }
147
148         /* Initialize struct watchdog_device */
149         wdd = &wdt->wdd;
150         wdd->parent = dev;
151         wdd->info = &ts4800_wdt_info;
152         wdd->ops = &ts4800_wdt_ops;
153         wdd->min_timeout = ts4800_wdt_map[0].timeout;
154         wdd->max_timeout = ts4800_wdt_map[MAX_TIMEOUT_INDEX].timeout;
155
156         watchdog_set_drvdata(wdd, wdt);
157         watchdog_set_nowayout(wdd, nowayout);
158         watchdog_init_timeout(wdd, 0, dev);
159
160         /*
161          * As this watchdog supports only a few values, ts4800_wdt_set_timeout
162          * must be called to initialize timeout and feed_val with valid values.
163          * Default to maximum timeout if none, or an invalid one, is provided in
164          * device tree.
165          */
166         if (!wdd->timeout)
167                 wdd->timeout = wdd->max_timeout;
168         ts4800_wdt_set_timeout(wdd, wdd->timeout);
169
170         /*
171          * The feed register is write-only, so it is not possible to determine
172          * watchdog's state. Disable it to be in a known state.
173          */
174         ts4800_wdt_stop(wdd);
175
176         ret = devm_watchdog_register_device(dev, wdd);
177         if (ret)
178                 return ret;
179
180         platform_set_drvdata(pdev, wdt);
181
182         dev_info(dev, "initialized (timeout = %d sec, nowayout = %d)\n",
183                  wdd->timeout, nowayout);
184
185         return 0;
186 }
187
188 static const struct of_device_id ts4800_wdt_of_match[] = {
189         { .compatible = "technologic,ts4800-wdt", },
190         { },
191 };
192 MODULE_DEVICE_TABLE(of, ts4800_wdt_of_match);
193
194 static struct platform_driver ts4800_wdt_driver = {
195         .probe          = ts4800_wdt_probe,
196         .driver         = {
197                 .name   = "ts4800_wdt",
198                 .of_match_table = ts4800_wdt_of_match,
199         },
200 };
201
202 module_platform_driver(ts4800_wdt_driver);
203
204 MODULE_AUTHOR("Damien Riegel <damien.riegel@savoirfairelinux.com>");
205 MODULE_LICENSE("GPL v2");
206 MODULE_ALIAS("platform:ts4800_wdt");