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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 static DEFINE_SPINLOCK(io_lock);
 43 
 44 static int nodelay;
 45 static void __iomem     *wdt_base;
 46 
 47 /*
 48  * The timeout values used are actually the absolute minimum the chip
 49  * offers. Typical values on my board are slightly over twice as long
 50  * (10s setting ends up with a 25s timeout), and can be up to 3 times
 51  * the nominal setting (according to the datasheet). So please take
 52  * these values with a grain of salt. Same goes for the initial delay
 53  * "feature". Only max6373/74 have a few settings without this initial
 54  * delay (selected with the "nodelay" parameter).
 55  *
 56  * I also decided to remove from the tables any timeout smaller than a
 57  * second, as it looked completly overkill...
 58  */
 59 
 60 /* Timeouts in second */
 61 struct max63xx_timeout {
 62         u8 wdset;
 63         u8 tdelay;
 64         u8 twd;
 65 };
 66 
 67 static struct max63xx_timeout max6369_table[] = {
 68         { 5,  1,  1 },
 69         { 6, 10, 10 },
 70         { 7, 60, 60 },
 71         { },
 72 };
 73 
 74 static struct max63xx_timeout max6371_table[] = {
 75         { 6, 60,  3 },
 76         { 7, 60, 60 },
 77         { },
 78 };
 79 
 80 static struct max63xx_timeout max6373_table[] = {
 81         { 2, 60,  1 },
 82         { 5,  0,  1 },
 83         { 1,  3,  3 },
 84         { 7, 60, 10 },
 85         { 6,  0, 10 },
 86         { },
 87 };
 88 
 89 static struct max63xx_timeout *current_timeout;
 90 
 91 static struct max63xx_timeout *
 92 max63xx_select_timeout(struct max63xx_timeout *table, int value)
 93 {
 94         while (table->twd) {
 95                 if (value <= table->twd) {
 96                         if (nodelay && table->tdelay == 0)
 97                                 return table;
 98 
 99                         if (!nodelay)
100                                 return table;
101                 }
102 
103                 table++;
104         }
105 
106         return NULL;
107 }
108 
109 static int max63xx_wdt_ping(struct watchdog_device *wdd)
110 {
111         u8 val;
112 
113         spin_lock(&io_lock);
114 
115         val = __raw_readb(wdt_base);
116 
117         __raw_writeb(val | MAX6369_WDI, wdt_base);
118         __raw_writeb(val & ~MAX6369_WDI, wdt_base);
119 
120         spin_unlock(&io_lock);
121         return 0;
122 }
123 
124 static int max63xx_wdt_start(struct watchdog_device *wdd)
125 {
126         struct max63xx_timeout *entry = watchdog_get_drvdata(wdd);
127         u8 val;
128 
129         spin_lock(&io_lock);
130 
131         val = __raw_readb(wdt_base);
132         val &= ~MAX6369_WDSET;
133         val |= entry->wdset;
134         __raw_writeb(val, wdt_base);
135 
136         spin_unlock(&io_lock);
137 
138         /* check for a edge triggered startup */
139         if (entry->tdelay == 0)
140                 max63xx_wdt_ping(wdd);
141         return 0;
142 }
143 
144 static int max63xx_wdt_stop(struct watchdog_device *wdd)
145 {
146         u8 val;
147 
148         spin_lock(&io_lock);
149 
150         val = __raw_readb(wdt_base);
151         val &= ~MAX6369_WDSET;
152         val |= 3;
153         __raw_writeb(val, wdt_base);
154 
155         spin_unlock(&io_lock);
156         return 0;
157 }
158 
159 static const struct watchdog_info max63xx_wdt_info = {
160         .options = WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
161         .identity = "max63xx Watchdog",
162 };
163 
164 static const struct watchdog_ops max63xx_wdt_ops = {
165         .owner = THIS_MODULE,
166         .start = max63xx_wdt_start,
167         .stop = max63xx_wdt_stop,
168         .ping = max63xx_wdt_ping,
169 };
170 
171 static struct watchdog_device max63xx_wdt_dev = {
172         .info = &max63xx_wdt_info,
173         .ops = &max63xx_wdt_ops,
174 };
175 
176 static int max63xx_wdt_probe(struct platform_device *pdev)
177 {
178         struct resource *wdt_mem;
179         struct max63xx_timeout *table;
180 
181         table = (struct max63xx_timeout *)pdev->id_entry->driver_data;
182 
183         if (heartbeat < 1 || heartbeat > MAX_HEARTBEAT)
184                 heartbeat = DEFAULT_HEARTBEAT;
185 
186         dev_info(&pdev->dev, "requesting %ds heartbeat\n", heartbeat);
187         current_timeout = max63xx_select_timeout(table, heartbeat);
188 
189         if (!current_timeout) {
190                 dev_err(&pdev->dev, "unable to satisfy heartbeat request\n");
191                 return -EINVAL;
192         }
193 
194         dev_info(&pdev->dev, "using %ds heartbeat with %ds initial delay\n",
195                  current_timeout->twd, current_timeout->tdelay);
196 
197         heartbeat = current_timeout->twd;
198 
199         wdt_mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
200         wdt_base = devm_ioremap_resource(&pdev->dev, wdt_mem);
201         if (IS_ERR(wdt_base))
202                 return PTR_ERR(wdt_base);
203 
204         max63xx_wdt_dev.timeout = heartbeat;
205         watchdog_set_nowayout(&max63xx_wdt_dev, nowayout);
206         watchdog_set_drvdata(&max63xx_wdt_dev, current_timeout);
207 
208         return watchdog_register_device(&max63xx_wdt_dev);
209 }
210 
211 static int max63xx_wdt_remove(struct platform_device *pdev)
212 {
213         watchdog_unregister_device(&max63xx_wdt_dev);
214         return 0;
215 }
216 
217 static struct platform_device_id max63xx_id_table[] = {
218         { "max6369_wdt", (kernel_ulong_t)max6369_table, },
219         { "max6370_wdt", (kernel_ulong_t)max6369_table, },
220         { "max6371_wdt", (kernel_ulong_t)max6371_table, },
221         { "max6372_wdt", (kernel_ulong_t)max6371_table, },
222         { "max6373_wdt", (kernel_ulong_t)max6373_table, },
223         { "max6374_wdt", (kernel_ulong_t)max6373_table, },
224         { },
225 };
226 MODULE_DEVICE_TABLE(platform, max63xx_id_table);
227 
228 static struct platform_driver max63xx_wdt_driver = {
229         .probe          = max63xx_wdt_probe,
230         .remove         = max63xx_wdt_remove,
231         .id_table       = max63xx_id_table,
232         .driver         = {
233                 .name   = "max63xx_wdt",
234                 .owner  = THIS_MODULE,
235         },
236 };
237 
238 module_platform_driver(max63xx_wdt_driver);
239 
240 MODULE_AUTHOR("Marc Zyngier <maz@misterjones.org>");
241 MODULE_DESCRIPTION("max63xx Watchdog Driver");
242 
243 module_param(heartbeat, int, 0);
244 MODULE_PARM_DESC(heartbeat,
245                  "Watchdog heartbeat period in seconds from 1 to "
246                  __MODULE_STRING(MAX_HEARTBEAT) ", default "
247                  __MODULE_STRING(DEFAULT_HEARTBEAT));
248 
249 module_param(nowayout, bool, 0);
250 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
251                  __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
252 
253 module_param(nodelay, int, 0);
254 MODULE_PARM_DESC(nodelay,
255                  "Force selection of a timeout setting without initial delay "
256                  "(max6373/74 only, default=0)");
257 
258 MODULE_LICENSE("GPL");
259 

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