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ARM: picoxcell: implement watchdog restart

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Allow the platform to be restarted by triggering the watchdog to expire
with the shortest possible expiry.  This should reset the CPU core and
all on-chip peripherals.

v2:	- use writel_relaxed().

Signed-off-by: Jamie Iles <jamie@jamieiles.com>
This commit is contained in:
Jamie Iles 2011-12-17 13:42:37 +00:00
parent a53bfa0736
commit 1b46f8782c
1 changed files with 37 additions and 0 deletions
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37
arch/arm/mach-picoxcell/common.c
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@ -7,6 +7,7 @@
*
* All enquiries to support@picochip.com
*/
#include <linux/delay.h>
#include <linux/irq.h>
#include <linux/irqdomain.h>
#include <linux/of.h>
@ -23,6 +24,26 @@
#include "common.h"
#define WDT_CTRL_REG_EN_MASK (1 << 0)
#define WDT_CTRL_REG_OFFS (0x00)
#define WDT_TIMEOUT_REG_OFFS (0x04)
static void __iomem *wdt_regs;
/*
* The machine restart method can be called from an atomic context so we won't
* be able to ioremap the regs then.
*/
static void picoxcell_setup_restart(void)
{
struct device_node *np = of_find_compatible_node(NULL, NULL,
"snps,dw-apb-wdg");
if (WARN(!np, "unable to setup watchdog restart"))
return;
wdt_regs = of_iomap(np, 0);
WARN(!wdt_regs, "failed to remap watchdog regs");
}
static struct map_desc io_map __initdata = {
.virtual = PHYS_TO_IO(PICOXCELL_PERIPH_BASE),
.pfn = __phys_to_pfn(PICOXCELL_PERIPH_BASE),
@ -38,6 +59,7 @@ static void __init picoxcell_map_io(void)
static void __init picoxcell_init_machine(void)
{
of_platform_populate(NULL, of_default_bus_match_table, NULL, NULL);
picoxcell_setup_restart();
}
static const char *picoxcell_dt_match[] = {
@ -56,6 +78,20 @@ static void __init picoxcell_init_irq(void)
of_irq_init(vic_of_match);
}
static void picoxcell_wdt_restart(char mode, const char *cmd)
{
/*
* Configure the watchdog to reset with the shortest possible timeout
* and give it chance to do the reset.
*/
if (wdt_regs) {
writel_relaxed(WDT_CTRL_REG_EN_MASK, wdt_regs + WDT_CTRL_REG_OFFS);
writel_relaxed(0, wdt_regs + WDT_TIMEOUT_REG_OFFS);
/* No sleeping, possibly atomic. */
mdelay(500);
}
}
DT_MACHINE_START(PICOXCELL, "Picochip picoXcell")
.map_io = picoxcell_map_io,
.nr_irqs = NR_IRQS_LEGACY,
@ -64,4 +100,5 @@ DT_MACHINE_START(PICOXCELL, "Picochip picoXcell")
.timer = &picoxcell_timer,
.init_machine = picoxcell_init_machine,
.dt_compat = picoxcell_dt_match,
.restart = picoxcell_wdt_restart,
MACHINE_END