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1 /*
2 * drivers/char/watchdog/max63xx_wdt.c
3 *
4 * Driver for max63{69,70,71,72,73,74} watchdog timers
5 *
6 * Copyright (C) 2009 Marc Zyngier <maz@misterjones.org>
7 *
8 * This file is licensed under the terms of the GNU General Public
9 * License version 2. This program is licensed "as is" without any
10 * warranty of any kind, whether express or implied.
11 *
12 * This driver assumes the watchdog pins are memory mapped (as it is
13 * the case for the Arcom Zeus). Should it be connected over GPIOs or
14 * another interface, some abstraction will have to be introduced.
15 */
16
17 #include <linux/err.h>
18 #include <linux/module.h>
19 #include <linux/moduleparam.h>
20 #include <linux/types.h>
21 #include <linux/kernel.h>
22 #include <linux/watchdog.h>
23 #include <linux/bitops.h>
24 #include <linux/platform_device.h>
25 #include <linux/spinlock.h>
26 #include <linux/io.h>
27 #include <linux/slab.h>
28
29 #define DEFAULT_HEARTBEAT 60
30 #define MAX_HEARTBEAT 60
31
32 static unsigned int heartbeat = DEFAULT_HEARTBEAT;
33 static bool nowayout = WATCHDOG_NOWAYOUT;
34
35 /*
36 * Memory mapping: a single byte, 3 first lower bits to select bit 3
37 * to ping the watchdog.
38 */
39 #define MAX6369_WDSET (7 << 0)
40 #define MAX6369_WDI (1 << 3)
41
42 #define MAX6369_WDSET_DISABLED 3
43
44 static int nodelay;
45
46 struct max63xx_wdt {
47 struct watchdog_device wdd;
48 const struct max63xx_timeout *timeout;
49
50 /* memory mapping */
51 void __iomem *base;
52 spinlock_t lock;
53
54 /* WDI and WSET bits write access routines */
55 void (*ping)(struct max63xx_wdt *wdt);
56 void (*set)(struct max63xx_wdt *wdt, u8 set);
57 };
58
59 /*
60 * The timeout values used are actually the absolute minimum the chip
61 * offers. Typical values on my board are slightly over twice as long
62 * (10s setting ends up with a 25s timeout), and can be up to 3 times
63 * the nominal setting (according to the datasheet). So please take
64 * these values with a grain of salt. Same goes for the initial delay
65 * "feature". Only max6373/74 have a few settings without this initial
66 * delay (selected with the "nodelay" parameter).
67 *
68 * I also decided to remove from the tables any timeout smaller than a
69 * second, as it looked completly overkill...
70 */
71
72 /* Timeouts in second */
73 struct max63xx_timeout {
74 const u8 wdset;
75 const u8 tdelay;
76 const u8 twd;
77 };
78
79 static const struct max63xx_timeout max6369_table[] = {
80 { 5, 1, 1 },
81 { 6, 10, 10 },
82 { 7, 60, 60 },
83 { },
84 };
85
86 static const struct max63xx_timeout max6371_table[] = {
87 { 6, 60, 3 },
88 { 7, 60, 60 },
89 { },
90 };
91
92 static const struct max63xx_timeout max6373_table[] = {
93 { 2, 60, 1 },
94 { 5, 0, 1 },
95 { 1, 3, 3 },
96 { 7, 60, 10 },
97 { 6, 0, 10 },
98 { },
99 };
100
101 static struct max63xx_timeout *
102 max63xx_select_timeout(struct max63xx_timeout *table, int value)
103 {
104 while (table->twd) {
105 if (value <= table->twd) {
106 if (nodelay && table->tdelay == 0)
107 return table;
108
109 if (!nodelay)
110 return table;
111 }
112
113 table++;
114 }
115
116 return NULL;
117 }
118
119 static int max63xx_wdt_ping(struct watchdog_device *wdd)
120 {
121 struct max63xx_wdt *wdt = watchdog_get_drvdata(wdd);
122
123 wdt->ping(wdt);
124 return 0;
125 }
126
127 static int max63xx_wdt_start(struct watchdog_device *wdd)
128 {
129 struct max63xx_wdt *wdt = watchdog_get_drvdata(wdd);
130
131 wdt->set(wdt, wdt->timeout->wdset);
132
133 /* check for a edge triggered startup */
134 if (wdt->timeout->tdelay == 0)
135 wdt->ping(wdt);
136 return 0;
137 }
138
139 static int max63xx_wdt_stop(struct watchdog_device *wdd)
140 {
141 struct max63xx_wdt *wdt = watchdog_get_drvdata(wdd);
142
143 wdt->set(wdt, MAX6369_WDSET_DISABLED);
144 return 0;
145 }
146
147 static const struct watchdog_ops max63xx_wdt_ops = {
148 .owner = THIS_MODULE,
149 .start = max63xx_wdt_start,
150 .stop = max63xx_wdt_stop,
151 .ping = max63xx_wdt_ping,
152 };
153
154 static const struct watchdog_info max63xx_wdt_info = {
155 .options = WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
156 .identity = "max63xx Watchdog",
157 };
158
159 static void max63xx_mmap_ping(struct max63xx_wdt *wdt)
160 {
161 u8 val;
162
163 spin_lock(&wdt->lock);
164
165 val = __raw_readb(wdt->base);
166
167 __raw_writeb(val | MAX6369_WDI, wdt->base);
168 __raw_writeb(val & ~MAX6369_WDI, wdt->base);
169
170 spin_unlock(&wdt->lock);
171 }
172
173 static void max63xx_mmap_set(struct max63xx_wdt *wdt, u8 set)
174 {
175 u8 val;
176
177 spin_lock(&wdt->lock);
178
179 val = __raw_readb(wdt->base);
180 val &= ~MAX6369_WDSET;
181 val |= set & MAX6369_WDSET;
182 __raw_writeb(val, wdt->base);
183
184 spin_unlock(&wdt->lock);
185 }
186
187 static int max63xx_mmap_init(struct platform_device *p, struct max63xx_wdt *wdt)
188 {
189 struct resource *mem = platform_get_resource(p, IORESOURCE_MEM, 0);
190
191 wdt->base = devm_ioremap_resource(&p->dev, mem);
192 if (IS_ERR(wdt->base))
193 return PTR_ERR(wdt->base);
194
195 spin_lock_init(&wdt->lock);
196
197 wdt->ping = max63xx_mmap_ping;
198 wdt->set = max63xx_mmap_set;
199 return 0;
200 }
201
202 static int max63xx_wdt_probe(struct platform_device *pdev)
203 {
204 struct max63xx_wdt *wdt;
205 struct max63xx_timeout *table;
206 int err;
207
208 wdt = devm_kzalloc(&pdev->dev, sizeof(*wdt), GFP_KERNEL);
209 if (!wdt)
210 return -ENOMEM;
211
212 table = (struct max63xx_timeout *)pdev->id_entry->driver_data;
213
214 if (heartbeat < 1 || heartbeat > MAX_HEARTBEAT)
215 heartbeat = DEFAULT_HEARTBEAT;
216
217 wdt->timeout = max63xx_select_timeout(table, heartbeat);
218 if (!wdt->timeout) {
219 dev_err(&pdev->dev, "unable to satisfy %ds heartbeat request\n",
220 heartbeat);
221 return -EINVAL;
222 }
223
224 err = max63xx_mmap_init(pdev, wdt);
225 if (err)
226 return err;
227
228 platform_set_drvdata(pdev, &wdt->wdd);
229 watchdog_set_drvdata(&wdt->wdd, wdt);
230
231 wdt->wdd.parent = &pdev->dev;
232 wdt->wdd.timeout = wdt->timeout->twd;
233 wdt->wdd.info = &max63xx_wdt_info;
234 wdt->wdd.ops = &max63xx_wdt_ops;
235
236 watchdog_set_nowayout(&wdt->wdd, nowayout);
237
238 err = watchdog_register_device(&wdt->wdd);
239 if (err)
240 return err;
241
242 dev_info(&pdev->dev, "using %ds heartbeat with %ds initial delay\n",
243 wdt->timeout->twd, wdt->timeout->tdelay);
244 return 0;
245 }
246
247 static int max63xx_wdt_remove(struct platform_device *pdev)
248 {
249 struct watchdog_device *wdd = platform_get_drvdata(pdev);
250
251 watchdog_unregister_device(wdd);
252 return 0;
253 }
254
255 static const struct platform_device_id max63xx_id_table[] = {
256 { "max6369_wdt", (kernel_ulong_t)max6369_table, },
257 { "max6370_wdt", (kernel_ulong_t)max6369_table, },
258 { "max6371_wdt", (kernel_ulong_t)max6371_table, },
259 { "max6372_wdt", (kernel_ulong_t)max6371_table, },
260 { "max6373_wdt", (kernel_ulong_t)max6373_table, },
261 { "max6374_wdt", (kernel_ulong_t)max6373_table, },
262 { },
263 };
264 MODULE_DEVICE_TABLE(platform, max63xx_id_table);
265
266 static struct platform_driver max63xx_wdt_driver = {
267 .probe = max63xx_wdt_probe,
268 .remove = max63xx_wdt_remove,
269 .id_table = max63xx_id_table,
270 .driver = {
271 .name = "max63xx_wdt",
272 },
273 };
274
275 module_platform_driver(max63xx_wdt_driver);
276
277 MODULE_AUTHOR("Marc Zyngier <maz@misterjones.org>");
278 MODULE_DESCRIPTION("max63xx Watchdog Driver");
279
280 module_param(heartbeat, int, 0);
281 MODULE_PARM_DESC(heartbeat,
282 "Watchdog heartbeat period in seconds from 1 to "
283 __MODULE_STRING(MAX_HEARTBEAT) ", default "
284 __MODULE_STRING(DEFAULT_HEARTBEAT));
285
286 module_param(nowayout, bool, 0);
287 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
288 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
289
290 module_param(nodelay, int, 0);
291 MODULE_PARM_DESC(nodelay,
292 "Force selection of a timeout setting without initial delay "
293 "(max6373/74 only, default=0)");
294
295 MODULE_LICENSE("GPL v2");