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 | |
57 | static void ts4800_write_feed(struct ts4800_wdt *wdt, u32 val) |
58 | { |
59 | regmap_write(map: wdt->regmap, reg: wdt->feed_offset, val); |
60 | } |
61 | |
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, val: wdt->feed_val); |
67 | return 0; |
68 | } |
69 | |
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 | |
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 | |
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, phandle_name: "syscon" , index: 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, propname: "syscon" , index: 1, out_value: ®); |
124 | if (ret < 0) { |
125 | dev_err(dev, "no offset in syscon\n" ); |
126 | of_node_put(node: syscon_np); |
127 | return ret; |
128 | } |
129 | |
130 | /* allocate memory for watchdog struct */ |
131 | wdt = devm_kzalloc(dev, size: sizeof(*wdt), GFP_KERNEL); |
132 | if (!wdt) { |
133 | of_node_put(node: 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(np: syscon_np); |
140 | of_node_put(node: syscon_np); |
141 | if (IS_ERR(ptr: wdt->regmap)) { |
142 | dev_err(dev, "cannot get parent's regmap\n" ); |
143 | return PTR_ERR(ptr: 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, data: wdt); |
155 | watchdog_set_nowayout(wdd, nowayout); |
156 | watchdog_init_timeout(wdd, timeout_parm: 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, timeout: 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, data: 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 | |