linux/drivers/watchdog/max63xx_wdt.c
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   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
  34static unsigned int heartbeat = DEFAULT_HEARTBEAT;
  35static 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
  44static DEFINE_SPINLOCK(io_lock);
  45
  46static int nodelay;
  47static 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 */
  63struct max63xx_timeout {
  64        u8 wdset;
  65        u8 tdelay;
  66        u8 twd;
  67};
  68
  69static struct max63xx_timeout max6369_table[] = {
  70        { 5,  1,  1 },
  71        { 6, 10, 10 },
  72        { 7, 60, 60 },
  73        { },
  74};
  75
  76static struct max63xx_timeout max6371_table[] = {
  77        { 6, 60,  3 },
  78        { 7, 60, 60 },
  79        { },
  80};
  81
  82static 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
  91static struct max63xx_timeout *current_timeout;
  92
  93static struct max63xx_timeout *
  94max63xx_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
 111static 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
 126static 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
 146static 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
 161static const struct watchdog_info max63xx_wdt_info = {
 162        .options = WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
 163        .identity = "max63xx Watchdog",
 164};
 165
 166static 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
 173static struct watchdog_device max63xx_wdt_dev = {
 174        .info = &max63xx_wdt_info,
 175        .ops = &max63xx_wdt_ops,
 176};
 177
 178static 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
 213static int max63xx_wdt_remove(struct platform_device *pdev)
 214{
 215        watchdog_unregister_device(&max63xx_wdt_dev);
 216        return 0;
 217}
 218
 219static 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};
 228MODULE_DEVICE_TABLE(platform, max63xx_id_table);
 229
 230static 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
 240module_platform_driver(max63xx_wdt_driver);
 241
 242MODULE_AUTHOR("Marc Zyngier <maz@misterjones.org>");
 243MODULE_DESCRIPTION("max63xx Watchdog Driver");
 244
 245module_param(heartbeat, int, 0);
 246MODULE_PARM_DESC(heartbeat,
 247                 "Watchdog heartbeat period in seconds from 1 to "
 248                 __MODULE_STRING(MAX_HEARTBEAT) ", default "
 249                 __MODULE_STRING(DEFAULT_HEARTBEAT));
 250
 251module_param(nowayout, bool, 0);
 252MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
 253                 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
 254
 255module_param(nodelay, int, 0);
 256MODULE_PARM_DESC(nodelay,
 257                 "Force selection of a timeout setting without initial delay "
 258                 "(max6373/74 only, default=0)");
 259
 260MODULE_LICENSE("GPL");
 261MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
 262
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