max63xx_wdt.c

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/*
 * drivers/char/watchdog/max63xx_wdt.c
 *
 * Driver for max63{69,70,71,72,73,74} watchdog timers
 *
 * Copyright (C) 2009 Marc Zyngier <[email protected]>
 *
 * This file is licensed under the terms of the GNU General Public
 * License version 2. This program is licensed "as is" without any
 * warranty of any kind, whether express or implied.
 *
 * This driver assumes the watchdog pins are memory mapped (as it is
 * the case for the Arcom Zeus). Should it be connected over GPIOs or
 * another interface, some abstraction will have to be introduced.
 */

#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/miscdevice.h>
#include <linux/watchdog.h>
#include <linux/init.h>
#include <linux/bitops.h>
#include <linux/platform_device.h>
#include <linux/spinlock.h>
#include <linux/io.h>
#include <linux/slab.h>

#define DEFAULT_HEARTBEAT 60
#define MAX_HEARTBEAT     60

static unsigned int heartbeat = DEFAULT_HEARTBEAT;
static bool nowayout  = WATCHDOG_NOWAYOUT;

/*
 * Memory mapping: a single byte, 3 first lower bits to select bit 3
 * to ping the watchdog.
 */
#define MAX6369_WDSET   (7 << 0)
#define MAX6369_WDI (1 << 3)

static DEFINE_SPINLOCK(io_lock);

static int nodelay;
static void __iomem *wdt_base;

/*
 * The timeout values used are actually the absolute minimum the chip
 * offers. Typical values on my board are slightly over twice as long
 * (10s setting ends up with a 25s timeout), and can be up to 3 times
 * the nominal setting (according to the datasheet). So please take
 * these values with a grain of salt. Same goes for the initial delay
 * "feature". Only max6373/74 have a few settings without this initial
 * delay (selected with the "nodelay" parameter).
 *
 * I also decided to remove from the tables any timeout smaller than a
 * second, as it looked completly overkill...
 */

/* Timeouts in second */
struct max63xx_timeout {
    u8 wdset;
    u8 tdelay;
    u8 twd;
};

static struct max63xx_timeout max6369_table[] = {
    { 5,  1,  1 },
    { 6, 10, 10 },
    { 7, 60, 60 },
    { },
};

static struct max63xx_timeout max6371_table[] = {
    { 6, 60,  3 },
    { 7, 60, 60 },
    { },
};

static struct max63xx_timeout max6373_table[] = {
    { 2, 60,  1 },
    { 5,  0,  1 },
    { 1,  3,  3 },
    { 7, 60, 10 },
    { 6,  0, 10 },
    { },
};

static struct max63xx_timeout *current_timeout;

static struct max63xx_timeout *
max63xx_select_timeout(struct max63xx_timeout *table, int value)
{
    while (table->twd) {
        if (value <= table->twd) {
            if (nodelay && table->tdelay == 0)
                return table;

            if (!nodelay)
                return table;
        }

        table++;
    }

    return NULL;
}

static int max63xx_wdt_ping(struct watchdog_device *wdd)
{
    u8 val;

    spin_lock(&io_lock);

    val = __raw_readb(wdt_base);

    __raw_writeb(val | MAX6369_WDI, wdt_base);
    __raw_writeb(val & ~MAX6369_WDI, wdt_base);

    spin_unlock(&io_lock);
    return 0;
}

static int max63xx_wdt_start(struct watchdog_device *wdd)
{
    struct max63xx_timeout *entry = watchdog_get_drvdata(wdd);
    u8 val;

    spin_lock(&io_lock);

    val = __raw_readb(wdt_base);
    val &= ~MAX6369_WDSET;
    val |= entry->wdset;
    __raw_writeb(val, wdt_base);

    spin_unlock(&io_lock);

    /* check for a edge triggered startup */
    if (entry->tdelay == 0)
        max63xx_wdt_ping(wdd);
    return 0;
}

static int max63xx_wdt_stop(struct watchdog_device *wdd)
{
    u8 val;

    spin_lock(&io_lock);

    val = __raw_readb(wdt_base);
    val &= ~MAX6369_WDSET;
    val |= 3;
    __raw_writeb(val, wdt_base);

    spin_unlock(&io_lock);
    return 0;
}

static const struct watchdog_info max63xx_wdt_info = {
    .options = WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
    .identity = "max63xx Watchdog",
};

static const struct watchdog_ops max63xx_wdt_ops = {
    .owner = THIS_MODULE,
    .start = max63xx_wdt_start,
    .stop = max63xx_wdt_stop,
    .ping = max63xx_wdt_ping,
};

static struct watchdog_device max63xx_wdt_dev = {
    .info = &max63xx_wdt_info,
    .ops = &max63xx_wdt_ops,
};

static int __devinit max63xx_wdt_probe(struct platform_device *pdev)
{
    struct resource *wdt_mem;
    struct max63xx_timeout *table;

    table = (struct max63xx_timeout *)pdev->id_entry->driver_data;

    if (heartbeat < 1 || heartbeat > MAX_HEARTBEAT)
        heartbeat = DEFAULT_HEARTBEAT;

    dev_info(&pdev->dev, "requesting %ds heartbeat\n", heartbeat);
    current_timeout = max63xx_select_timeout(table, heartbeat);

    if (!current_timeout) {
        dev_err(&pdev->dev, "unable to satisfy heartbeat request\n");
        return -EINVAL;
    }

    dev_info(&pdev->dev, "using %ds heartbeat with %ds initial delay\n",
         current_timeout->twd, current_timeout->tdelay);

    heartbeat = current_timeout->twd;

    wdt_mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
    wdt_base = devm_request_and_ioremap(&pdev->dev, wdt_mem);
    if (!wdt_base)
        return -ENOMEM;

    max63xx_wdt_dev.timeout = heartbeat;
    watchdog_set_nowayout(&max63xx_wdt_dev, nowayout);
    watchdog_set_drvdata(&max63xx_wdt_dev, current_timeout);

    return watchdog_register_device(&max63xx_wdt_dev);
}

static int __devexit max63xx_wdt_remove(struct platform_device *pdev)
{
    watchdog_unregister_device(&max63xx_wdt_dev);
    return 0;
}

static struct platform_device_id max63xx_id_table[] = {
    { "max6369_wdt", (kernel_ulong_t)max6369_table, },
    { "max6370_wdt", (kernel_ulong_t)max6369_table, },
    { "max6371_wdt", (kernel_ulong_t)max6371_table, },
    { "max6372_wdt", (kernel_ulong_t)max6371_table, },
    { "max6373_wdt", (kernel_ulong_t)max6373_table, },
    { "max6374_wdt", (kernel_ulong_t)max6373_table, },
    { },
};
MODULE_DEVICE_TABLE(platform, max63xx_id_table);

static struct platform_driver max63xx_wdt_driver = {
    .probe      = max63xx_wdt_probe,
    .remove     = __devexit_p(max63xx_wdt_remove),
    .id_table   = max63xx_id_table,
    .driver     = {
        .name   = "max63xx_wdt",
        .owner  = THIS_MODULE,
    },
};

module_platform_driver(max63xx_wdt_driver);

MODULE_AUTHOR("Marc Zyngier <[email protected]>");
MODULE_DESCRIPTION("max63xx Watchdog Driver");

module_param(heartbeat, int, 0);
MODULE_PARM_DESC(heartbeat,
         "Watchdog heartbeat period in seconds from 1 to "
         __MODULE_STRING(MAX_HEARTBEAT) ", default "
         __MODULE_STRING(DEFAULT_HEARTBEAT));

module_param(nowayout, bool, 0);
MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
         __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");

module_param(nodelay, int, 0);
MODULE_PARM_DESC(nodelay,
         "Force selection of a timeout setting without initial delay "
         "(max6373/74 only, default=0)");

MODULE_LICENSE("GPL");
MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);