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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/init.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 
 30 #define DEFAULT_HEARTBEAT 60
 31 #define MAX_HEARTBEAT     60
 32 
 33 static unsigned int heartbeat = DEFAULT_HEARTBEAT;
 34 static bool nowayout  = WATCHDOG_NOWAYOUT;
 35 
 36 /*
 37  * Memory mapping: a single byte, 3 first lower bits to select bit 3
 38  * to ping the watchdog.
 39  */
 40 #define MAX6369_WDSET   (7 << 0)
 41 #define MAX6369_WDI     (1 << 3)
 42 
 43 static DEFINE_SPINLOCK(io_lock);
 44 
 45 static int nodelay;
 46 static void __iomem     *wdt_base;
 47 
 48 /*
 49  * The timeout values used are actually the absolute minimum the chip
 50  * offers. Typical values on my board are slightly over twice as long
 51  * (10s setting ends up with a 25s timeout), and can be up to 3 times
 52  * the nominal setting (according to the datasheet). So please take
 53  * these values with a grain of salt. Same goes for the initial delay
 54  * "feature". Only max6373/74 have a few settings without this initial
 55  * delay (selected with the "nodelay" parameter).
 56  *
 57  * I also decided to remove from the tables any timeout smaller than a
 58  * second, as it looked completly overkill...
 59  */
 60 
 61 /* Timeouts in second */
 62 struct max63xx_timeout {
 63         u8 wdset;
 64         u8 tdelay;
 65         u8 twd;
 66 };
 67 
 68 static struct max63xx_timeout max6369_table[] = {
 69         { 5,  1,  1 },
 70         { 6, 10, 10 },
 71         { 7, 60, 60 },
 72         { },
 73 };
 74 
 75 static struct max63xx_timeout max6371_table[] = {
 76         { 6, 60,  3 },
 77         { 7, 60, 60 },
 78         { },
 79 };
 80 
 81 static struct max63xx_timeout max6373_table[] = {
 82         { 2, 60,  1 },
 83         { 5,  0,  1 },
 84         { 1,  3,  3 },
 85         { 7, 60, 10 },
 86         { 6,  0, 10 },
 87         { },
 88 };
 89 
 90 static struct max63xx_timeout *current_timeout;
 91 
 92 static struct max63xx_timeout *
 93 max63xx_select_timeout(struct max63xx_timeout *table, int value)
 94 {
 95         while (table->twd) {
 96                 if (value <= table->twd) {
 97                         if (nodelay && table->tdelay == 0)
 98                                 return table;
 99 
100                         if (!nodelay)
101                                 return table;
102                 }
103 
104                 table++;
105         }
106 
107         return NULL;
108 }
109 
110 static int max63xx_wdt_ping(struct watchdog_device *wdd)
111 {
112         u8 val;
113 
114         spin_lock(&io_lock);
115 
116         val = __raw_readb(wdt_base);
117 
118         __raw_writeb(val | MAX6369_WDI, wdt_base);
119         __raw_writeb(val & ~MAX6369_WDI, wdt_base);
120 
121         spin_unlock(&io_lock);
122         return 0;
123 }
124 
125 static int max63xx_wdt_start(struct watchdog_device *wdd)
126 {
127         struct max63xx_timeout *entry = watchdog_get_drvdata(wdd);
128         u8 val;
129 
130         spin_lock(&io_lock);
131 
132         val = __raw_readb(wdt_base);
133         val &= ~MAX6369_WDSET;
134         val |= entry->wdset;
135         __raw_writeb(val, wdt_base);
136 
137         spin_unlock(&io_lock);
138 
139         /* check for a edge triggered startup */
140         if (entry->tdelay == 0)
141                 max63xx_wdt_ping(wdd);
142         return 0;
143 }
144 
145 static int max63xx_wdt_stop(struct watchdog_device *wdd)
146 {
147         u8 val;
148 
149         spin_lock(&io_lock);
150 
151         val = __raw_readb(wdt_base);
152         val &= ~MAX6369_WDSET;
153         val |= 3;
154         __raw_writeb(val, wdt_base);
155 
156         spin_unlock(&io_lock);
157         return 0;
158 }
159 
160 static const struct watchdog_info max63xx_wdt_info = {
161         .options = WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
162         .identity = "max63xx Watchdog",
163 };
164 
165 static const struct watchdog_ops max63xx_wdt_ops = {
166         .owner = THIS_MODULE,
167         .start = max63xx_wdt_start,
168         .stop = max63xx_wdt_stop,
169         .ping = max63xx_wdt_ping,
170 };
171 
172 static struct watchdog_device max63xx_wdt_dev = {
173         .info = &max63xx_wdt_info,
174         .ops = &max63xx_wdt_ops,
175 };
176 
177 static int max63xx_wdt_probe(struct platform_device *pdev)
178 {
179         struct resource *wdt_mem;
180         struct max63xx_timeout *table;
181 
182         table = (struct max63xx_timeout *)pdev->id_entry->driver_data;
183 
184         if (heartbeat < 1 || heartbeat > MAX_HEARTBEAT)
185                 heartbeat = DEFAULT_HEARTBEAT;
186 
187         dev_info(&pdev->dev, "requesting %ds heartbeat\n", heartbeat);
188         current_timeout = max63xx_select_timeout(table, heartbeat);
189 
190         if (!current_timeout) {
191                 dev_err(&pdev->dev, "unable to satisfy heartbeat request\n");
192                 return -EINVAL;
193         }
194 
195         dev_info(&pdev->dev, "using %ds heartbeat with %ds initial delay\n",
196                  current_timeout->twd, current_timeout->tdelay);
197 
198         heartbeat = current_timeout->twd;
199 
200         wdt_mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
201         wdt_base = devm_ioremap_resource(&pdev->dev, wdt_mem);
202         if (IS_ERR(wdt_base))
203                 return PTR_ERR(wdt_base);
204 
205         max63xx_wdt_dev.timeout = heartbeat;
206         watchdog_set_nowayout(&max63xx_wdt_dev, nowayout);
207         watchdog_set_drvdata(&max63xx_wdt_dev, current_timeout);
208 
209         return watchdog_register_device(&max63xx_wdt_dev);
210 }
211 
212 static int max63xx_wdt_remove(struct platform_device *pdev)
213 {
214         watchdog_unregister_device(&max63xx_wdt_dev);
215         return 0;
216 }
217 
218 static struct platform_device_id max63xx_id_table[] = {
219         { "max6369_wdt", (kernel_ulong_t)max6369_table, },
220         { "max6370_wdt", (kernel_ulong_t)max6369_table, },
221         { "max6371_wdt", (kernel_ulong_t)max6371_table, },
222         { "max6372_wdt", (kernel_ulong_t)max6371_table, },
223         { "max6373_wdt", (kernel_ulong_t)max6373_table, },
224         { "max6374_wdt", (kernel_ulong_t)max6373_table, },
225         { },
226 };
227 MODULE_DEVICE_TABLE(platform, max63xx_id_table);
228 
229 static struct platform_driver max63xx_wdt_driver = {
230         .probe          = max63xx_wdt_probe,
231         .remove         = max63xx_wdt_remove,
232         .id_table       = max63xx_id_table,
233         .driver         = {
234                 .name   = "max63xx_wdt",
235                 .owner  = THIS_MODULE,
236         },
237 };
238 
239 module_platform_driver(max63xx_wdt_driver);
240 
241 MODULE_AUTHOR("Marc Zyngier <maz@misterjones.org>");
242 MODULE_DESCRIPTION("max63xx Watchdog Driver");
243 
244 module_param(heartbeat, int, 0);
245 MODULE_PARM_DESC(heartbeat,
246                  "Watchdog heartbeat period in seconds from 1 to "
247                  __MODULE_STRING(MAX_HEARTBEAT) ", default "
248                  __MODULE_STRING(DEFAULT_HEARTBEAT));
249 
250 module_param(nowayout, bool, 0);
251 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
252                  __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
253 
254 module_param(nodelay, int, 0);
255 MODULE_PARM_DESC(nodelay,
256                  "Force selection of a timeout setting without initial delay "
257                  "(max6373/74 only, default=0)");
258 
259 MODULE_LICENSE("GPL");
260 

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