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