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         },
 235 };
 236
 237 module_platform_driver(max63xx_wdt_driver);
 238
 239 MODULE_AUTHOR("Marc Zyngier <maz@misterjones.org>");
 240 MODULE_DESCRIPTION("max63xx Watchdog Driver");
 241
 242 module_param(heartbeat, int, 0);
 243 MODULE_PARM_DESC(heartbeat,
 244                  "Watchdog heartbeat period in seconds from 1 to "
 245                  __MODULE_STRING(MAX_HEARTBEAT) ", default "
 246                  __MODULE_STRING(DEFAULT_HEARTBEAT));
 247
 248 module_param(nowayout, bool, 0);
 249 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
 250                  __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
 251
 252 module_param(nodelay, int, 0);
 253 MODULE_PARM_DESC(nodelay,
 254                  "Force selection of a timeout setting without initial delay "
 255                  "(max6373/74 only, default=0)");
 256
 257 MODULE_LICENSE("GPL");