diff options
Diffstat (limited to 'drivers/watchdog/max63xx_wdt.c')
| -rw-r--r-- | drivers/watchdog/max63xx_wdt.c | 260 |
1 files changed, 260 insertions, 0 deletions
diff --git a/drivers/watchdog/max63xx_wdt.c b/drivers/watchdog/max63xx_wdt.c new file mode 100644 index 00000000..8f4a74e9 --- /dev/null +++ b/drivers/watchdog/max63xx_wdt.c @@ -0,0 +1,260 @@ +/* + * drivers/char/watchdog/max63xx_wdt.c + * + * Driver for max63{69,70,71,72,73,74} watchdog timers + * + * Copyright (C) 2009 Marc Zyngier <maz@misterjones.org> + * + * 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 <maz@misterjones.org>"); +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); |