linux/drivers/watchdog/max63xx_wdt.c
<<
>>
Prefs
   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
  33static unsigned int heartbeat = DEFAULT_HEARTBEAT;
  34static 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
  43static DEFINE_SPINLOCK(io_lock);
  44
  45static int nodelay;
  46static 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 */
  62struct max63xx_timeout {
  63        u8 wdset;
  64        u8 tdelay;
  65        u8 twd;
  66};
  67
  68static struct max63xx_timeout max6369_table[] = {
  69        { 5,  1,  1 },
  70        { 6, 10, 10 },
  71        { 7, 60, 60 },
  72        { },
  73};
  74
  75static struct max63xx_timeout max6371_table[] = {
  76        { 6, 60,  3 },
  77        { 7, 60, 60 },
  78        { },
  79};
  80
  81static 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
  90static struct max63xx_timeout *current_timeout;
  91
  92static struct max63xx_timeout *
  93max63xx_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
 110static 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
 125static 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
 145static 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
 160static const struct watchdog_info max63xx_wdt_info = {
 161        .options = WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
 162        .identity = "max63xx Watchdog",
 163};
 164
 165static 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
 172static struct watchdog_device max63xx_wdt_dev = {
 173        .info = &max63xx_wdt_info,
 174        .ops = &max63xx_wdt_ops,
 175};
 176
 177static 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
 212static int __devexit max63xx_wdt_remove(struct platform_device *pdev)
 213{
 214        watchdog_unregister_device(&max63xx_wdt_dev);
 215        return 0;
 216}
 217
 218static 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};
 227MODULE_DEVICE_TABLE(platform, max63xx_id_table);
 228
 229static 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
 239module_platform_driver(max63xx_wdt_driver);
 240
 241MODULE_AUTHOR("Marc Zyngier <maz@misterjones.org>");
 242MODULE_DESCRIPTION("max63xx Watchdog Driver");
 243
 244module_param(heartbeat, int, 0);
 245MODULE_PARM_DESC(heartbeat,
 246                 "Watchdog heartbeat period in seconds from 1 to "
 247                 __MODULE_STRING(MAX_HEARTBEAT) ", default "
 248                 __MODULE_STRING(DEFAULT_HEARTBEAT));
 249
 250module_param(nowayout, bool, 0);
 251MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
 252                 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
 253
 254module_param(nodelay, int, 0);
 255MODULE_PARM_DESC(nodelay,
 256                 "Force selection of a timeout setting without initial delay "
 257                 "(max6373/74 only, default=0)");
 258
 259MODULE_LICENSE("GPL");
 260MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
 261
lxr.linux.no kindly hosted by Redpill Linpro AS, provider of Linux consulting and operations services since 1995.