/*
* Watchdog driver for Broadcom BCM2835
*
* "bcm2708_wdog" driver written by Luke Diamand that was obtained from
* branch "rpi-3.6.y" of git://github.com/raspberrypi/linux.git was used
* as a hardware reference for the Broadcom BCM2835 watchdog timer.
*
* Copyright (C) 2013 Lubomir Rintel <lkundrak@v3.sk>
*
* This program is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License as published by the
* Free Software Foundation; either version 2 of the License, or (at your
* option) any later version.
*/
#include <linux/delay.h>
#include <linux/types.h>
#include <linux/module.h>
#include <linux/io.h>
#include <linux/watchdog.h>
#include <linux/platform_device.h>
#include <linux/of_address.h>
#include <linux/of_platform.h>
#define PM_RSTC 0x1c
#define PM_RSTS 0x20
#define PM_WDOG 0x24
#define PM_PASSWORD 0x5a000000
#define PM_WDOG_TIME_SET 0x000fffff
#define PM_RSTC_WRCFG_CLR 0xffffffcf
#define PM_RSTS_HADWRH_SET 0x00000040
#define PM_RSTC_WRCFG_SET 0x00000030
#define PM_RSTC_WRCFG_FULL_RESET 0x00000020
#define PM_RSTC_RESET 0x00000102
/*
* The Raspberry Pi firmware uses the RSTS register to know which partition
* to boot from. The partition value is spread into bits 0, 2, 4, 6, 8, 10.
* Partition 63 is a special partition used by the firmware to indicate halt.
*/
#define PM_RSTS_RASPBERRYPI_HALT 0x555
#define SECS_TO_WDOG_TICKS(x) ((x) << 16)
#define WDOG_TICKS_TO_SECS(x) ((x) >> 16)
struct bcm2835_wdt {
void __iomem *base;
spinlock_t lock;
};
static unsigned int heartbeat;
static bool nowayout = WATCHDOG_NOWAYOUT;
static bool bcm2835_wdt_is_running(struct bcm2835_wdt *wdt)
{
uint32_t cur;
cur = readl(wdt->base + PM_RSTC);
return !!(cur & PM_RSTC_WRCFG_FULL_RESET);
}
static int bcm2835_wdt_start(struct watchdog_device *wdog)
{
struct bcm2835_wdt *wdt = watchdog_get_drvdata(wdog);
uint32_t cur;
unsigned long flags;
spin_lock_irqsave(&wdt->lock, flags);
writel_relaxed(PM_PASSWORD | (SECS_TO_WDOG_TICKS(wdog->timeout) &
PM_WDOG_TIME_SET), wdt->base + PM_WDOG);
cur = readl_relaxed(wdt->base + PM_RSTC);
writel_relaxed(PM_PASSWORD | (cur & PM_RSTC_WRCFG_CLR) |
PM_RSTC_WRCFG_FULL_RESET, wdt->base + PM_RSTC);
spin_unlock_irqrestore(&wdt->lock, flags);
return 0;
}
static int bcm2835_wdt_stop(struct watchdog_device *wdog)
{
struct bcm2835_wdt *wdt = watchdog_get_drvdata(wdog);
writel_relaxed(PM_PASSWORD | PM_RSTC_RESET, wdt->base + PM_RSTC);
return 0;
}
static unsigned int bcm2835_wdt_get_timeleft(struct watchdog_device *wdog)
{
struct bcm2835_wdt *wdt = watchdog_get_drvdata(wdog);
uint32_t ret = readl_relaxed(wdt->base + PM_WDOG);
return WDOG_TICKS_TO_SECS(ret & PM_WDOG_TIME_SET);
}
static void __bcm2835_restart(struct bcm2835_wdt *wdt)
{
u32 val;
/* use a timeout of 10 ticks (~150us) */
writel_relaxed(10 | PM_PASSWORD, wdt->base + PM_WDOG);
val = readl_relaxed(wdt->base + PM_RSTC);
val &= PM_RSTC_WRCFG_CLR;
val |= PM_PASSWORD | PM_RSTC_WRCFG_FULL_RESET;
writel_relaxed(val, wdt->base + PM_RSTC);
/* No sleeping, possibly atomic. */
mdelay(1);
}
static int bcm2835_restart(struct watchdog_device *wdog,
unsigned long action, void *data)
{
struct bcm2835_wdt *wdt = watchdog_get_drvdata(wdog);
__bcm2835_restart(wdt);
return 0;
}
static const struct watchdog_ops bcm2835_wdt_ops = {
.owner = THIS_MODULE,
.start = bcm2835_wdt_start,
.stop = bcm2835_wdt_stop,
.get_timeleft = bcm2835_wdt_get_timeleft,
.restart = bcm2835_restart,
};
static const struct watchdog_info bcm2835_wdt_info = {
.options = WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE |
WDIOF_KEEPALIVEPING,
.identity = "Broadcom BCM2835 Watchdog timer",
};
static struct watchdog_device bcm2835_wdt_wdd = {
.info = &bcm2835_wdt_info,
.ops = &bcm2835_wdt_ops,
.min_timeout = 1,
.max_timeout = WDOG_TICKS_TO_SECS(PM_WDOG_TIME_SET),
.timeout = WDOG_TICKS_TO_SECS(PM_WDOG_TIME_SET),
};
/*
* We can't really power off, but if we do the normal reset scheme, and
* indicate to bootcode.bin not to reboot, then most of the chip will be
* powered off.
*/
static void bcm2835_power_off(void)
{
struct device_node *np =
of_find_compatible_node(NULL, NULL, "brcm,bcm2835-pm-wdt");
struct platform_device *pdev = of_find_device_by_node(np);
struct bcm2835_wdt *wdt = platform_get_drvdata(pdev);
u32 val;
/*
* We set the watchdog hard reset bit here to distinguish this reset
* from the normal (full) reset. bootcode.bin will not reboot after a
* hard reset.
*/
val = readl_relaxed(wdt->base + PM_RSTS);
val |= PM_PASSWORD | PM_RSTS_RASPBERRYPI_HALT;
writel_relaxed(val, wdt->base + PM_RSTS);
/* Continue with normal reset mechanism */
__bcm2835_restart(wdt);
}
static int bcm2835_wdt_probe(struct platform_device *pdev)
{
struct resource *res;
struct device *dev = &pdev->dev;
struct bcm2835_wdt *wdt;
int err;
wdt = devm_kzalloc(dev, sizeof(struct bcm2835_wdt), GFP_KERNEL);
if (!wdt)
return -ENOMEM;
platform_set_drvdata(pdev, wdt);
spin_lock_init(&wdt->lock);
res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
wdt->base = devm_ioremap_resource(dev, res);
if (IS_ERR(wdt->base))
return PTR_ERR(wdt->base);
watchdog_set_drvdata(&bcm2835_wdt_wdd, wdt);
watchdog_init_timeout(&bcm2835_wdt_wdd, heartbeat, dev);
watchdog_set_nowayout(&bcm2835_wdt_wdd, nowayout);
bcm2835_wdt_wdd.parent = dev;
if (bcm2835_wdt_is_running(wdt)) {
/*
* The currently active timeout value (set by the
* bootloader) may be different from the module
* heartbeat parameter or the value in device
* tree. But we just need to set WDOG_HW_RUNNING,
* because then the framework will "immediately" ping
* the device, updating the timeout.
*/
set_bit(WDOG_HW_RUNNING, &bcm2835_wdt_wdd.status);
}
watchdog_set_restart_priority(&bcm2835_wdt_wdd, 128);
watchdog_stop_on_reboot(&bcm2835_wdt_wdd);
err = devm_watchdog_register_device(dev, &bcm2835_wdt_wdd);
if (err) {
dev_err(dev, "Failed to register watchdog device");
return err;
}
if (pm_power_off == NULL)
pm_power_off = bcm2835_power_off;
dev_info(dev, "Broadcom BCM2835 watchdog timer");
return 0;
}
static int bcm2835_wdt_remove(struct platform_device *pdev)
{
if (pm_power_off == bcm2835_power_off)
pm_power_off = NULL;
return 0;
}
static const struct of_device_id bcm2835_wdt_of_match[] = {
{ .compatible = "brcm,bcm2835-pm-wdt", },
{},
};
MODULE_DEVICE_TABLE(of, bcm2835_wdt_of_match);
static struct platform_driver bcm2835_wdt_driver = {
.probe = bcm2835_wdt_probe,
.remove = bcm2835_wdt_remove,
.driver = {
.name = "bcm2835-wdt",
.of_match_table = bcm2835_wdt_of_match,
},
};
module_platform_driver(bcm2835_wdt_driver);
module_param(heartbeat, uint, 0);
MODULE_PARM_DESC(heartbeat, "Initial watchdog heartbeat in seconds");
module_param(nowayout, bool, 0);
MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
__MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
MODULE_AUTHOR("Lubomir Rintel <lkundrak@v3.sk>");
MODULE_DESCRIPTION("Driver for Broadcom BCM2835 watchdog timer");
MODULE_LICENSE("GPL");
