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/mod_devicetable.h>
21 #include <linux/types.h>
22 #include <linux/kernel.h>
23 #include <linux/watchdog.h>
24 #include <linux/bitops.h>
25 #include <linux/platform_device.h>
26 #include <linux/spinlock.h>
27 #include <linux/io.h>
28 #include <linux/slab.h>
29 #include <linux/property.h>
30
31 #define DEFAULT_HEARTBEAT 60
32 #define MAX_HEARTBEAT 60
33
34 static unsigned int heartbeat = DEFAULT_HEARTBEAT;
35 static bool nowayout = WATCHDOG_NOWAYOUT;
36
37 /*
38 * Memory mapping: a single byte, 3 first lower bits to select bit 3
39 * to ping the watchdog.
40 */
41 #define MAX6369_WDSET (7 << 0)
42 #define MAX6369_WDI (1 << 3)
43
44 #define MAX6369_WDSET_DISABLED 3
45
46 static int nodelay;
47
48 struct max63xx_wdt {
49 struct watchdog_device wdd;
50 const struct max63xx_timeout *timeout;
51
52 /* memory mapping */
53 void __iomem *base;
54 spinlock_t lock;
55
56 /* WDI and WSET bits write access routines */
57 void (*ping)(struct max63xx_wdt *wdt);
58 void (*set)(struct max63xx_wdt *wdt, u8 set);
59 };
60
61 /*
62 * The timeout values used are actually the absolute minimum the chip
63 * offers. Typical values on my board are slightly over twice as long
64 * (10s setting ends up with a 25s timeout), and can be up to 3 times
65 * the nominal setting (according to the datasheet). So please take
66 * these values with a grain of salt. Same goes for the initial delay
67 * "feature". Only max6373/74 have a few settings without this initial
68 * delay (selected with the "nodelay" parameter).
69 *
70 * I also decided to remove from the tables any timeout smaller than a
71 * second, as it looked completly overkill...
72 */
73
74 /* Timeouts in second */
75 struct max63xx_timeout {
76 const u8 wdset;
77 const u8 tdelay;
78 const u8 twd;
79 };
80
81 static const struct max63xx_timeout max6369_table[] = {
82 { 5, 1, 1 },
83 { 6, 10, 10 },
84 { 7, 60, 60 },
85 { },
86 };
87
88 static const struct max63xx_timeout max6371_table[] = {
89 { 6, 60, 3 },
90 { 7, 60, 60 },
91 { },
92 };
93
94 static const struct max63xx_timeout max6373_table[] = {
95 { 2, 60, 1 },
96 { 5, 0, 1 },
97 { 1, 3, 3 },
98 { 7, 60, 10 },
99 { 6, 0, 10 },
100 { },
101 };
102
103 static const struct max63xx_timeout *
max63xx_select_timeout(const struct max63xx_timeout * table,int value)104 max63xx_select_timeout(const struct max63xx_timeout *table, int value)
105 {
106 while (table->twd) {
107 if (value <= table->twd) {
108 if (nodelay && table->tdelay == 0)
109 return table;
110
111 if (!nodelay)
112 return table;
113 }
114
115 table++;
116 }
117
118 return NULL;
119 }
120
max63xx_wdt_ping(struct watchdog_device * wdd)121 static int max63xx_wdt_ping(struct watchdog_device *wdd)
122 {
123 struct max63xx_wdt *wdt = watchdog_get_drvdata(wdd);
124
125 wdt->ping(wdt);
126 return 0;
127 }
128
max63xx_wdt_start(struct watchdog_device * wdd)129 static int max63xx_wdt_start(struct watchdog_device *wdd)
130 {
131 struct max63xx_wdt *wdt = watchdog_get_drvdata(wdd);
132
133 wdt->set(wdt, wdt->timeout->wdset);
134
135 /* check for a edge triggered startup */
136 if (wdt->timeout->tdelay == 0)
137 wdt->ping(wdt);
138 return 0;
139 }
140
max63xx_wdt_stop(struct watchdog_device * wdd)141 static int max63xx_wdt_stop(struct watchdog_device *wdd)
142 {
143 struct max63xx_wdt *wdt = watchdog_get_drvdata(wdd);
144
145 wdt->set(wdt, MAX6369_WDSET_DISABLED);
146 return 0;
147 }
148
149 static const struct watchdog_ops max63xx_wdt_ops = {
150 .owner = THIS_MODULE,
151 .start = max63xx_wdt_start,
152 .stop = max63xx_wdt_stop,
153 .ping = max63xx_wdt_ping,
154 };
155
156 static const struct watchdog_info max63xx_wdt_info = {
157 .options = WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
158 .identity = "max63xx Watchdog",
159 };
160
max63xx_mmap_ping(struct max63xx_wdt * wdt)161 static void max63xx_mmap_ping(struct max63xx_wdt *wdt)
162 {
163 u8 val;
164
165 spin_lock(&wdt->lock);
166
167 val = __raw_readb(wdt->base);
168
169 __raw_writeb(val | MAX6369_WDI, wdt->base);
170 __raw_writeb(val & ~MAX6369_WDI, wdt->base);
171
172 spin_unlock(&wdt->lock);
173 }
174
max63xx_mmap_set(struct max63xx_wdt * wdt,u8 set)175 static void max63xx_mmap_set(struct max63xx_wdt *wdt, u8 set)
176 {
177 u8 val;
178
179 spin_lock(&wdt->lock);
180
181 val = __raw_readb(wdt->base);
182 val &= ~MAX6369_WDSET;
183 val |= set & MAX6369_WDSET;
184 __raw_writeb(val, wdt->base);
185
186 spin_unlock(&wdt->lock);
187 }
188
max63xx_mmap_init(struct platform_device * p,struct max63xx_wdt * wdt)189 static int max63xx_mmap_init(struct platform_device *p, struct max63xx_wdt *wdt)
190 {
191 wdt->base = devm_platform_ioremap_resource(p, 0);
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
max63xx_wdt_probe(struct platform_device * pdev)202 static int max63xx_wdt_probe(struct platform_device *pdev)
203 {
204 struct device *dev = &pdev->dev;
205 struct max63xx_wdt *wdt;
206 const struct max63xx_timeout *table;
207 int err;
208
209 wdt = devm_kzalloc(dev, sizeof(*wdt), GFP_KERNEL);
210 if (!wdt)
211 return -ENOMEM;
212
213 /* Attempt to use fwnode first */
214 table = device_get_match_data(dev);
215 if (!table)
216 table = (struct max63xx_timeout *)pdev->id_entry->driver_data;
217
218 if (heartbeat < 1 || heartbeat > MAX_HEARTBEAT)
219 heartbeat = DEFAULT_HEARTBEAT;
220
221 wdt->timeout = max63xx_select_timeout(table, heartbeat);
222 if (!wdt->timeout) {
223 dev_err(dev, "unable to satisfy %ds heartbeat request\n",
224 heartbeat);
225 return -EINVAL;
226 }
227
228 err = max63xx_mmap_init(pdev, wdt);
229 if (err)
230 return err;
231
232 platform_set_drvdata(pdev, &wdt->wdd);
233 watchdog_set_drvdata(&wdt->wdd, wdt);
234
235 wdt->wdd.parent = dev;
236 wdt->wdd.timeout = wdt->timeout->twd;
237 wdt->wdd.info = &max63xx_wdt_info;
238 wdt->wdd.ops = &max63xx_wdt_ops;
239
240 watchdog_set_nowayout(&wdt->wdd, nowayout);
241
242 err = devm_watchdog_register_device(dev, &wdt->wdd);
243 if (err)
244 return err;
245
246 dev_info(dev, "using %ds heartbeat with %ds initial delay\n",
247 wdt->timeout->twd, wdt->timeout->tdelay);
248 return 0;
249 }
250
251 static const struct platform_device_id max63xx_id_table[] = {
252 { "max6369_wdt", (kernel_ulong_t)max6369_table, },
253 { "max6370_wdt", (kernel_ulong_t)max6369_table, },
254 { "max6371_wdt", (kernel_ulong_t)max6371_table, },
255 { "max6372_wdt", (kernel_ulong_t)max6371_table, },
256 { "max6373_wdt", (kernel_ulong_t)max6373_table, },
257 { "max6374_wdt", (kernel_ulong_t)max6373_table, },
258 { },
259 };
260 MODULE_DEVICE_TABLE(platform, max63xx_id_table);
261
262 static const struct of_device_id max63xx_dt_id_table[] = {
263 { .compatible = "maxim,max6369", .data = max6369_table, },
264 { .compatible = "maxim,max6370", .data = max6369_table, },
265 { .compatible = "maxim,max6371", .data = max6371_table, },
266 { .compatible = "maxim,max6372", .data = max6371_table, },
267 { .compatible = "maxim,max6373", .data = max6373_table, },
268 { .compatible = "maxim,max6374", .data = max6373_table, },
269 { }
270 };
271 MODULE_DEVICE_TABLE(of, max63xx_dt_id_table);
272
273 static struct platform_driver max63xx_wdt_driver = {
274 .probe = max63xx_wdt_probe,
275 .id_table = max63xx_id_table,
276 .driver = {
277 .name = "max63xx_wdt",
278 .of_match_table = max63xx_dt_id_table,
279 },
280 };
281
282 module_platform_driver(max63xx_wdt_driver);
283
284 MODULE_AUTHOR("Marc Zyngier <maz@misterjones.org>");
285 MODULE_DESCRIPTION("max63xx Watchdog Driver");
286
287 module_param(heartbeat, int, 0);
288 MODULE_PARM_DESC(heartbeat,
289 "Watchdog heartbeat period in seconds from 1 to "
290 __MODULE_STRING(MAX_HEARTBEAT) ", default "
291 __MODULE_STRING(DEFAULT_HEARTBEAT));
292
293 module_param(nowayout, bool, 0);
294 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
295 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
296
297 module_param(nodelay, int, 0);
298 MODULE_PARM_DESC(nodelay,
299 "Force selection of a timeout setting without initial delay "
300 "(max6373/74 only, default=0)");
301
302 MODULE_LICENSE("GPL v2");
303