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Linux/drivers/watchdog/max63xx_wdt.c

  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");
296 

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