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/module.h>
  18 #include <linux/moduleparam.h>
  19 #include <linux/types.h>
  20 #include <linux/kernel.h>
  21 #include <linux/miscdevice.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 __devinit 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_request_and_ioremap(&pdev->dev, wdt_mem);
 202         if (!wdt_base)
 203                 return -ENOMEM;
 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 __devexit 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         = __devexit_p(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 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);