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linux/drivers/watchdog/coh901327_wdt.c

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/*
* coh901327_wdt.c
*
* Copyright (C) 2008-2009 ST-Ericsson AB
* License terms: GNU General Public License (GPL) version 2
* Watchdog driver for the ST-Ericsson AB COH 901 327 IP core
* Author: Linus Walleij <linus.walleij@stericsson.com>
*/
#include <linux/module.h>
#include <linux/types.h>
#include <linux/watchdog.h>
#include <linux/interrupt.h>
#include <linux/pm.h>
#include <linux/platform_device.h>
#include <linux/io.h>
#include <linux/bitops.h>
#include <linux/clk.h>
#include <linux/delay.h>
#include <linux/err.h>
#define DRV_NAME "WDOG COH 901 327"
/*
* COH 901 327 register definitions
*/
/* WDOG_FEED Register 32bit (-/W) */
#define U300_WDOG_FR 0x00
#define U300_WDOG_FR_FEED_RESTART_TIMER 0xFEEDU
/* WDOG_TIMEOUT Register 32bit (R/W) */
#define U300_WDOG_TR 0x04
#define U300_WDOG_TR_TIMEOUT_MASK 0x7FFFU
/* WDOG_DISABLE1 Register 32bit (-/W) */
#define U300_WDOG_D1R 0x08
#define U300_WDOG_D1R_DISABLE1_DISABLE_TIMER 0x2BADU
/* WDOG_DISABLE2 Register 32bit (R/W) */
#define U300_WDOG_D2R 0x0C
#define U300_WDOG_D2R_DISABLE2_DISABLE_TIMER 0xCAFEU
#define U300_WDOG_D2R_DISABLE_STATUS_DISABLED 0xDABEU
#define U300_WDOG_D2R_DISABLE_STATUS_ENABLED 0x0000U
/* WDOG_STATUS Register 32bit (R/W) */
#define U300_WDOG_SR 0x10
#define U300_WDOG_SR_STATUS_TIMED_OUT 0xCFE8U
#define U300_WDOG_SR_STATUS_NORMAL 0x0000U
#define U300_WDOG_SR_RESET_STATUS_RESET 0xE8B4U
/* WDOG_COUNT Register 32bit (R/-) */
#define U300_WDOG_CR 0x14
#define U300_WDOG_CR_VALID_IND 0x8000U
#define U300_WDOG_CR_VALID_STABLE 0x0000U
#define U300_WDOG_CR_COUNT_VALUE_MASK 0x7FFFU
/* WDOG_JTAGOVR Register 32bit (R/W) */
#define U300_WDOG_JOR 0x18
#define U300_WDOG_JOR_JTAG_MODE_IND 0x0002U
#define U300_WDOG_JOR_JTAG_WATCHDOG_ENABLE 0x0001U
/* WDOG_RESTART Register 32bit (-/W) */
#define U300_WDOG_RR 0x1C
#define U300_WDOG_RR_RESTART_VALUE_RESUME 0xACEDU
/* WDOG_IRQ_EVENT Register 32bit (R/W) */
#define U300_WDOG_IER 0x20
#define U300_WDOG_IER_WILL_BARK_IRQ_EVENT_IND 0x0001U
#define U300_WDOG_IER_WILL_BARK_IRQ_ACK_ENABLE 0x0001U
/* WDOG_IRQ_MASK Register 32bit (R/W) */
#define U300_WDOG_IMR 0x24
#define U300_WDOG_IMR_WILL_BARK_IRQ_ENABLE 0x0001U
/* WDOG_IRQ_FORCE Register 32bit (R/W) */
#define U300_WDOG_IFR 0x28
#define U300_WDOG_IFR_WILL_BARK_IRQ_FORCE_ENABLE 0x0001U
/* Default timeout in seconds = 1 minute */
static unsigned int margin = 60;
static resource_size_t phybase;
static resource_size_t physize;
static int irq;
static void __iomem *virtbase;
static struct device *parent;
/*
* The watchdog block is of course always clocked, the
* clk_enable()/clk_disable() calls are mainly for performing reference
* counting higher up in the clock hierarchy.
*/
static struct clk *clk;
/*
* Enabling and disabling functions.
*/
static void coh901327_enable(u16 timeout)
{
u16 val;
unsigned long freq;
unsigned long delay_ns;
clk_enable(clk);
/* Restart timer if it is disabled */
val = readw(virtbase + U300_WDOG_D2R);
if (val == U300_WDOG_D2R_DISABLE_STATUS_DISABLED)
writew(U300_WDOG_RR_RESTART_VALUE_RESUME,
virtbase + U300_WDOG_RR);
/* Acknowledge any pending interrupt so it doesn't just fire off */
writew(U300_WDOG_IER_WILL_BARK_IRQ_ACK_ENABLE,
virtbase + U300_WDOG_IER);
/*
* The interrupt is cleared in the 32 kHz clock domain.
* Wait 3 32 kHz cycles for it to take effect
*/
freq = clk_get_rate(clk);
delay_ns = DIV_ROUND_UP(1000000000, freq); /* Freq to ns and round up */
delay_ns = 3 * delay_ns; /* Wait 3 cycles */
ndelay(delay_ns);
/* Enable the watchdog interrupt */
writew(U300_WDOG_IMR_WILL_BARK_IRQ_ENABLE, virtbase + U300_WDOG_IMR);
/* Activate the watchdog timer */
writew(timeout, virtbase + U300_WDOG_TR);
/* Start the watchdog timer */
writew(U300_WDOG_FR_FEED_RESTART_TIMER, virtbase + U300_WDOG_FR);
/*
* Extra read so that this change propagate in the watchdog.
*/
(void) readw(virtbase + U300_WDOG_CR);
val = readw(virtbase + U300_WDOG_D2R);
clk_disable(clk);
if (val != U300_WDOG_D2R_DISABLE_STATUS_ENABLED)
dev_err(parent,
"%s(): watchdog not enabled! D2R value %04x\n",
__func__, val);
}
static void coh901327_disable(void)
{
u16 val;
clk_enable(clk);
/* Disable the watchdog interrupt if it is active */
writew(0x0000U, virtbase + U300_WDOG_IMR);
/* If the watchdog is currently enabled, attempt to disable it */
val = readw(virtbase + U300_WDOG_D2R);
if (val != U300_WDOG_D2R_DISABLE_STATUS_DISABLED) {
writew(U300_WDOG_D1R_DISABLE1_DISABLE_TIMER,
virtbase + U300_WDOG_D1R);
writew(U300_WDOG_D2R_DISABLE2_DISABLE_TIMER,
virtbase + U300_WDOG_D2R);
/* Write this twice (else problems occur) */
writew(U300_WDOG_D2R_DISABLE2_DISABLE_TIMER,
virtbase + U300_WDOG_D2R);
}
val = readw(virtbase + U300_WDOG_D2R);
clk_disable(clk);
if (val != U300_WDOG_D2R_DISABLE_STATUS_DISABLED)
dev_err(parent,
"%s(): watchdog not disabled! D2R value %04x\n",
__func__, val);
}
static int coh901327_start(struct watchdog_device *wdt_dev)
{
coh901327_enable(wdt_dev->timeout * 100);
return 0;
}
static int coh901327_stop(struct watchdog_device *wdt_dev)
{
coh901327_disable();
return 0;
}
static int coh901327_ping(struct watchdog_device *wdd)
{
clk_enable(clk);
/* Feed the watchdog */
writew(U300_WDOG_FR_FEED_RESTART_TIMER,
virtbase + U300_WDOG_FR);
clk_disable(clk);
return 0;
}
static int coh901327_settimeout(struct watchdog_device *wdt_dev,
unsigned int time)
{
wdt_dev->timeout = time;
clk_enable(clk);
/* Set new timeout value */
writew(time * 100, virtbase + U300_WDOG_TR);
/* Feed the dog */
writew(U300_WDOG_FR_FEED_RESTART_TIMER,
virtbase + U300_WDOG_FR);
clk_disable(clk);
return 0;
}
static unsigned int coh901327_gettimeleft(struct watchdog_device *wdt_dev)
{
u16 val;
clk_enable(clk);
/* Read repeatedly until the value is stable! */
val = readw(virtbase + U300_WDOG_CR);
while (val & U300_WDOG_CR_VALID_IND)
val = readw(virtbase + U300_WDOG_CR);
val &= U300_WDOG_CR_COUNT_VALUE_MASK;
clk_disable(clk);
if (val != 0)
val /= 100;
return val;
}
/*
* This interrupt occurs 10 ms before the watchdog WILL bark.
*/
static irqreturn_t coh901327_interrupt(int irq, void *data)
{
u16 val;
/*
* Ack IRQ? If this occurs we're FUBAR anyway, so
* just acknowledge, disable the interrupt and await the imminent end.
* If you at some point need a host of callbacks to be called
* when the system is about to watchdog-reset, add them here!
*
* NOTE: on future versions of this IP-block, it will be possible
* to prevent a watchdog reset by feeding the watchdog at this
* point.
*/
clk_enable(clk);
val = readw(virtbase + U300_WDOG_IER);
if (val == U300_WDOG_IER_WILL_BARK_IRQ_EVENT_IND)
writew(U300_WDOG_IER_WILL_BARK_IRQ_ACK_ENABLE,
virtbase + U300_WDOG_IER);
writew(0x0000U, virtbase + U300_WDOG_IMR);
clk_disable(clk);
dev_crit(parent, "watchdog is barking!\n");
return IRQ_HANDLED;
}
static const struct watchdog_info coh901327_ident = {
.options = WDIOF_CARDRESET | WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING,
.identity = DRV_NAME,
};
static struct watchdog_ops coh901327_ops = {
.owner = THIS_MODULE,
.start = coh901327_start,
.stop = coh901327_stop,
.ping = coh901327_ping,
.set_timeout = coh901327_settimeout,
.get_timeleft = coh901327_gettimeleft,
};
static struct watchdog_device coh901327_wdt = {
.info = &coh901327_ident,
.ops = &coh901327_ops,
/*
* Max timeout is 327 since the 10ms
* timeout register is max
* 0x7FFF = 327670ms ~= 327s.
*/
.min_timeout = 0,
.max_timeout = 327,
};
static int __exit coh901327_remove(struct platform_device *pdev)
{
watchdog_unregister_device(&coh901327_wdt);
coh901327_disable();
free_irq(irq, pdev);
clk_unprepare(clk);
clk_put(clk);
iounmap(virtbase);
release_mem_region(phybase, physize);
return 0;
}
static int __init coh901327_probe(struct platform_device *pdev)
{
int ret;
u16 val;
struct resource *res;
res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
if (!res)
return -ENOENT;
parent = &pdev->dev;
physize = resource_size(res);
phybase = res->start;
if (request_mem_region(phybase, physize, DRV_NAME) == NULL) {
ret = -EBUSY;
goto out;
}
virtbase = ioremap(phybase, physize);
if (!virtbase) {
ret = -ENOMEM;
goto out_no_remap;
}
clk = clk_get(&pdev->dev, NULL);
if (IS_ERR(clk)) {
ret = PTR_ERR(clk);
dev_err(&pdev->dev, "could not get clock\n");
goto out_no_clk;
}
ret = clk_prepare_enable(clk);
if (ret) {
dev_err(&pdev->dev, "could not prepare and enable clock\n");
goto out_no_clk_enable;
}
val = readw(virtbase + U300_WDOG_SR);
switch (val) {
case U300_WDOG_SR_STATUS_TIMED_OUT:
dev_info(&pdev->dev,
"watchdog timed out since last chip reset!\n");
coh901327_wdt.bootstatus |= WDIOF_CARDRESET;
/* Status will be cleared below */
break;
case U300_WDOG_SR_STATUS_NORMAL:
dev_info(&pdev->dev,
"in normal status, no timeouts have occurred.\n");
break;
default:
dev_info(&pdev->dev,
"contains an illegal status code (%08x)\n", val);
break;
}
val = readw(virtbase + U300_WDOG_D2R);
switch (val) {
case U300_WDOG_D2R_DISABLE_STATUS_DISABLED:
dev_info(&pdev->dev, "currently disabled.\n");
break;
case U300_WDOG_D2R_DISABLE_STATUS_ENABLED:
dev_info(&pdev->dev,
"currently enabled! (disabling it now)\n");
coh901327_disable();
break;
default:
dev_err(&pdev->dev,
"contains an illegal enable/disable code (%08x)\n",
val);
break;
}
/* Reset the watchdog */
writew(U300_WDOG_SR_RESET_STATUS_RESET, virtbase + U300_WDOG_SR);
irq = platform_get_irq(pdev, 0);
if (request_irq(irq, coh901327_interrupt, 0,
DRV_NAME " Bark", pdev)) {
ret = -EIO;
goto out_no_irq;
}
clk_disable(clk);
ret = watchdog_init_timeout(&coh901327_wdt, margin, &pdev->dev);
if (ret < 0)
coh901327_wdt.timeout = 60;
ret = watchdog_register_device(&coh901327_wdt);
if (ret == 0)
dev_info(&pdev->dev,
"initialized. timer margin=%d sec\n", margin);
else
goto out_no_wdog;
return 0;
out_no_wdog:
free_irq(irq, pdev);
out_no_irq:
clk_disable_unprepare(clk);
out_no_clk_enable:
clk_put(clk);
out_no_clk:
iounmap(virtbase);
out_no_remap:
release_mem_region(phybase, SZ_4K);
out:
return ret;
}
#ifdef CONFIG_PM
static u16 wdogenablestore;
static u16 irqmaskstore;
static int coh901327_suspend(struct platform_device *pdev, pm_message_t state)
{
irqmaskstore = readw(virtbase + U300_WDOG_IMR) & 0x0001U;
wdogenablestore = readw(virtbase + U300_WDOG_D2R);
/* If watchdog is on, disable it here and now */
if (wdogenablestore == U300_WDOG_D2R_DISABLE_STATUS_ENABLED)
coh901327_disable();
return 0;
}
static int coh901327_resume(struct platform_device *pdev)
{
/* Restore the watchdog interrupt */
writew(irqmaskstore, virtbase + U300_WDOG_IMR);
if (wdogenablestore == U300_WDOG_D2R_DISABLE_STATUS_ENABLED) {
/* Restart the watchdog timer */
writew(U300_WDOG_RR_RESTART_VALUE_RESUME,
virtbase + U300_WDOG_RR);
writew(U300_WDOG_FR_FEED_RESTART_TIMER,
virtbase + U300_WDOG_FR);
}
return 0;
}
#else
#define coh901327_suspend NULL
#define coh901327_resume NULL
#endif
/*
* Mistreating the watchdog is the only way to perform a software reset of the
* system on EMP platforms. So we implement this and export a symbol for it.
*/
void coh901327_watchdog_reset(void)
{
/* Enable even if on JTAG too */
writew(U300_WDOG_JOR_JTAG_WATCHDOG_ENABLE,
virtbase + U300_WDOG_JOR);
/*
* Timeout = 5s, we have to wait for the watchdog reset to
* actually take place: the watchdog will be reloaded with the
* default value immediately, so we HAVE to reboot and get back
* into the kernel in 30s, or the device will reboot again!
* The boot loader will typically deactivate the watchdog, so we
* need time enough for the boot loader to get to the point of
* deactivating the watchdog before it is shut down by it.
*
* NOTE: on future versions of the watchdog, this restriction is
* gone: the watchdog will be reloaded with a default value (1 min)
* instead of last value, and you can conveniently set the watchdog
* timeout to 10ms (value = 1) without any problems.
*/
coh901327_enable(500);
/* Return and await doom */
}
static const struct of_device_id coh901327_dt_match[] = {
{ .compatible = "stericsson,coh901327" },
{},
};
static struct platform_driver coh901327_driver = {
.driver = {
.owner = THIS_MODULE,
.name = "coh901327_wdog",
.of_match_table = coh901327_dt_match,
},
.remove = __exit_p(coh901327_remove),
.suspend = coh901327_suspend,
.resume = coh901327_resume,
};
module_platform_driver_probe(coh901327_driver, coh901327_probe);
MODULE_AUTHOR("Linus Walleij <linus.walleij@stericsson.com>");
MODULE_DESCRIPTION("COH 901 327 Watchdog");
module_param(margin, uint, 0);
MODULE_PARM_DESC(margin, "Watchdog margin in seconds (default 60s)");
MODULE_LICENSE("GPL");
MODULE_ALIAS("platform:coh901327-watchdog");
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