258 lines
6.2 KiB
C
258 lines
6.2 KiB
C
/*
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* drivers/char/watchdog/max63xx_wdt.c
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*
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* Driver for max63{69,70,71,72,73,74} watchdog timers
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*
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* Copyright (C) 2009 Marc Zyngier <maz@misterjones.org>
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*
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* This file is licensed under the terms of the GNU General Public
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* License version 2. This program is licensed "as is" without any
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* warranty of any kind, whether express or implied.
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*
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* This driver assumes the watchdog pins are memory mapped (as it is
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* the case for the Arcom Zeus). Should it be connected over GPIOs or
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* another interface, some abstraction will have to be introduced.
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*/
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#include <linux/err.h>
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#include <linux/module.h>
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#include <linux/moduleparam.h>
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#include <linux/types.h>
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#include <linux/kernel.h>
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#include <linux/watchdog.h>
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#include <linux/bitops.h>
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#include <linux/platform_device.h>
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#include <linux/spinlock.h>
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#include <linux/io.h>
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#include <linux/slab.h>
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#define DEFAULT_HEARTBEAT 60
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#define MAX_HEARTBEAT 60
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static unsigned int heartbeat = DEFAULT_HEARTBEAT;
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static bool nowayout = WATCHDOG_NOWAYOUT;
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/*
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* Memory mapping: a single byte, 3 first lower bits to select bit 3
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* to ping the watchdog.
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*/
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#define MAX6369_WDSET (7 << 0)
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#define MAX6369_WDI (1 << 3)
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static DEFINE_SPINLOCK(io_lock);
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static int nodelay;
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static void __iomem *wdt_base;
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/*
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* The timeout values used are actually the absolute minimum the chip
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* offers. Typical values on my board are slightly over twice as long
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* (10s setting ends up with a 25s timeout), and can be up to 3 times
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* the nominal setting (according to the datasheet). So please take
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* these values with a grain of salt. Same goes for the initial delay
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* "feature". Only max6373/74 have a few settings without this initial
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* delay (selected with the "nodelay" parameter).
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*
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* I also decided to remove from the tables any timeout smaller than a
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* second, as it looked completly overkill...
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*/
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/* Timeouts in second */
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struct max63xx_timeout {
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u8 wdset;
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u8 tdelay;
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u8 twd;
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};
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static struct max63xx_timeout max6369_table[] = {
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{ 5, 1, 1 },
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{ 6, 10, 10 },
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{ 7, 60, 60 },
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{ },
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};
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static struct max63xx_timeout max6371_table[] = {
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{ 6, 60, 3 },
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{ 7, 60, 60 },
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{ },
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};
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static struct max63xx_timeout max6373_table[] = {
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{ 2, 60, 1 },
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{ 5, 0, 1 },
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{ 1, 3, 3 },
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{ 7, 60, 10 },
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{ 6, 0, 10 },
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{ },
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};
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static struct max63xx_timeout *current_timeout;
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static struct max63xx_timeout *
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max63xx_select_timeout(struct max63xx_timeout *table, int value)
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{
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while (table->twd) {
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if (value <= table->twd) {
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if (nodelay && table->tdelay == 0)
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return table;
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if (!nodelay)
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return table;
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}
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table++;
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}
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return NULL;
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}
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static int max63xx_wdt_ping(struct watchdog_device *wdd)
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{
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u8 val;
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spin_lock(&io_lock);
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val = __raw_readb(wdt_base);
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__raw_writeb(val | MAX6369_WDI, wdt_base);
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__raw_writeb(val & ~MAX6369_WDI, wdt_base);
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spin_unlock(&io_lock);
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return 0;
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}
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static int max63xx_wdt_start(struct watchdog_device *wdd)
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{
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struct max63xx_timeout *entry = watchdog_get_drvdata(wdd);
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u8 val;
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spin_lock(&io_lock);
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val = __raw_readb(wdt_base);
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val &= ~MAX6369_WDSET;
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val |= entry->wdset;
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__raw_writeb(val, wdt_base);
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spin_unlock(&io_lock);
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/* check for a edge triggered startup */
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if (entry->tdelay == 0)
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max63xx_wdt_ping(wdd);
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return 0;
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}
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static int max63xx_wdt_stop(struct watchdog_device *wdd)
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{
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u8 val;
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spin_lock(&io_lock);
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val = __raw_readb(wdt_base);
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val &= ~MAX6369_WDSET;
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val |= 3;
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__raw_writeb(val, wdt_base);
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spin_unlock(&io_lock);
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return 0;
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}
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static const struct watchdog_info max63xx_wdt_info = {
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.options = WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
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.identity = "max63xx Watchdog",
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};
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static const struct watchdog_ops max63xx_wdt_ops = {
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.owner = THIS_MODULE,
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.start = max63xx_wdt_start,
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.stop = max63xx_wdt_stop,
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.ping = max63xx_wdt_ping,
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};
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static struct watchdog_device max63xx_wdt_dev = {
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.info = &max63xx_wdt_info,
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.ops = &max63xx_wdt_ops,
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};
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static int max63xx_wdt_probe(struct platform_device *pdev)
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{
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struct resource *wdt_mem;
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struct max63xx_timeout *table;
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table = (struct max63xx_timeout *)pdev->id_entry->driver_data;
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if (heartbeat < 1 || heartbeat > MAX_HEARTBEAT)
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heartbeat = DEFAULT_HEARTBEAT;
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dev_info(&pdev->dev, "requesting %ds heartbeat\n", heartbeat);
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current_timeout = max63xx_select_timeout(table, heartbeat);
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if (!current_timeout) {
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dev_err(&pdev->dev, "unable to satisfy heartbeat request\n");
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return -EINVAL;
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}
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dev_info(&pdev->dev, "using %ds heartbeat with %ds initial delay\n",
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current_timeout->twd, current_timeout->tdelay);
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heartbeat = current_timeout->twd;
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wdt_mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
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wdt_base = devm_ioremap_resource(&pdev->dev, wdt_mem);
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if (IS_ERR(wdt_base))
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return PTR_ERR(wdt_base);
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max63xx_wdt_dev.timeout = heartbeat;
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watchdog_set_nowayout(&max63xx_wdt_dev, nowayout);
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watchdog_set_drvdata(&max63xx_wdt_dev, current_timeout);
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return watchdog_register_device(&max63xx_wdt_dev);
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}
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static int max63xx_wdt_remove(struct platform_device *pdev)
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{
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watchdog_unregister_device(&max63xx_wdt_dev);
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return 0;
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}
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static struct platform_device_id max63xx_id_table[] = {
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{ "max6369_wdt", (kernel_ulong_t)max6369_table, },
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{ "max6370_wdt", (kernel_ulong_t)max6369_table, },
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{ "max6371_wdt", (kernel_ulong_t)max6371_table, },
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{ "max6372_wdt", (kernel_ulong_t)max6371_table, },
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{ "max6373_wdt", (kernel_ulong_t)max6373_table, },
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{ "max6374_wdt", (kernel_ulong_t)max6373_table, },
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{ },
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};
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MODULE_DEVICE_TABLE(platform, max63xx_id_table);
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static struct platform_driver max63xx_wdt_driver = {
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.probe = max63xx_wdt_probe,
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.remove = max63xx_wdt_remove,
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.id_table = max63xx_id_table,
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.driver = {
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.name = "max63xx_wdt",
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},
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};
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module_platform_driver(max63xx_wdt_driver);
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MODULE_AUTHOR("Marc Zyngier <maz@misterjones.org>");
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MODULE_DESCRIPTION("max63xx Watchdog Driver");
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module_param(heartbeat, int, 0);
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MODULE_PARM_DESC(heartbeat,
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"Watchdog heartbeat period in seconds from 1 to "
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__MODULE_STRING(MAX_HEARTBEAT) ", default "
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__MODULE_STRING(DEFAULT_HEARTBEAT));
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module_param(nowayout, bool, 0);
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MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
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__MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
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module_param(nodelay, int, 0);
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MODULE_PARM_DESC(nodelay,
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"Force selection of a timeout setting without initial delay "
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"(max6373/74 only, default=0)");
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MODULE_LICENSE("GPL");
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