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watchdog: rza_wdt: Support longer timeouts 

The RZ/A2 watchdog timer extends the clock source options in order to
allow for longer timeouts.

Signed-off-by: Chris Brandt <chris.brandt@renesas.com>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@linux-watchdog.org>
This commit is contained in:
Chris Brandt 2018-09-24 08:58:15 -05:00 committed by Wim Van Sebroeck
parent 10d790d1fa
commit 8e89130632
1 changed files with 70 additions and 18 deletions
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88
drivers/watchdog/rza_wdt.c
View File

@ -11,6 +11,7 @@
#include <linux/delay.h>
#include <linux/module.h>
#include <linux/of_address.h>
#include <linux/of_device.h>
#include <linux/platform_device.h>
#include <linux/watchdog.h>
@ -31,12 +32,45 @@
#define WRCSR_RSTE BIT(6)
#define WRCSR_CLEAR_WOVF 0xA500 /* special value */
/* The maximum CKS register setting value to get the longest timeout */
#define CKS_3BIT 0x7
#define CKS_4BIT 0xF
#define DIVIDER_3BIT 16384 /* Clock divider when CKS = 0x7 */
#define DIVIDER_4BIT 4194304 /* Clock divider when CKS = 0xF */
struct rza_wdt {
struct watchdog_device wdev;
void __iomem *base;
struct clk *clk;
u8 count;
u8 cks;
};
static void rza_wdt_calc_timeout(struct rza_wdt *priv, int timeout)
{
unsigned long rate = clk_get_rate(priv->clk);
unsigned int ticks;
if (priv->cks == CKS_4BIT) {
ticks = DIV_ROUND_UP(timeout * rate, DIVIDER_4BIT);
/*
* Since max_timeout was set in probe, we know that the timeout
* value passed will never calculate to a tick value greater
* than 256.
*/
priv->count = 256 - ticks;
} else {
/* Start timer with longest timeout */
priv->count = 0;
}
pr_debug("%s: timeout set to %u (WTCNT=%d)\n", __func__,
timeout, priv->count);
}
static int rza_wdt_start(struct watchdog_device *wdev)
{
struct rza_wdt *priv = watchdog_get_drvdata(wdev);
@ -48,13 +82,12 @@ static int rza_wdt_start(struct watchdog_device *wdev)
readb(priv->base + WRCSR);
writew(WRCSR_CLEAR_WOVF, priv->base + WRCSR);
/*
* Start timer with slowest clock source and reset option enabled.
*/
rza_wdt_calc_timeout(priv, wdev->timeout);
writew(WRCSR_MAGIC | WRCSR_RSTE, priv->base + WRCSR);
writew(WTCNT_MAGIC | 0, priv->base + WTCNT);
writew(WTCSR_MAGIC | WTSCR_WT | WTSCR_TME | WTSCR_CKS(7),
priv->base + WTCSR);
writew(WTCNT_MAGIC | priv->count, priv->base + WTCNT);
writew(WTCSR_MAGIC | WTSCR_WT | WTSCR_TME |
WTSCR_CKS(priv->cks), priv->base + WTCSR);
return 0;
}
@ -72,8 +105,17 @@ static int rza_wdt_ping(struct watchdog_device *wdev)
{
struct rza_wdt *priv = watchdog_get_drvdata(wdev);
writew(WTCNT_MAGIC | 0, priv->base + WTCNT);
writew(WTCNT_MAGIC | priv->count, priv->base + WTCNT);
pr_debug("%s: timeout = %u\n", __func__, wdev->timeout);
return 0;
}
static int rza_set_timeout(struct watchdog_device *wdev, unsigned int timeout)
{
wdev->timeout = timeout;
rza_wdt_start(wdev);
return 0;
}
@ -118,6 +160,7 @@ static const struct watchdog_ops rza_wdt_ops = {
.start = rza_wdt_start,
.stop = rza_wdt_stop,
.ping = rza_wdt_ping,
.set_timeout = rza_set_timeout,
.restart = rza_wdt_restart,
};
@ -147,20 +190,28 @@ static int rza_wdt_probe(struct platform_device *pdev)
return -ENOENT;
}
/* Assume slowest clock rate possible (CKS=7) */
rate /= 16384;
priv->wdev.info = &rza_wdt_ident,
priv->wdev.ops = &rza_wdt_ops,
priv->wdev.parent = &pdev->dev;
/*
* Since the max possible timeout of our 8-bit count register is less
* than a second, we must use max_hw_heartbeat_ms.
*/
priv->wdev.max_hw_heartbeat_ms = (1000 * U8_MAX) / rate;
dev_dbg(&pdev->dev, "max hw timeout of %dms\n",
priv->wdev.max_hw_heartbeat_ms);
priv->cks = (u8)(uintptr_t)of_device_get_match_data(&pdev->dev);
if (priv->cks == CKS_4BIT) {
/* Assume slowest clock rate possible (CKS=0xF) */
priv->wdev.max_timeout = (DIVIDER_4BIT * U8_MAX) / rate;
} else if (priv->cks == CKS_3BIT) {
/* Assume slowest clock rate possible (CKS=7) */
rate /= DIVIDER_3BIT;
/*
* Since the max possible timeout of our 8-bit count
* register is less than a second, we must use
* max_hw_heartbeat_ms.
*/
priv->wdev.max_hw_heartbeat_ms = (1000 * U8_MAX) / rate;
dev_dbg(&pdev->dev, "max hw timeout of %dms\n",
priv->wdev.max_hw_heartbeat_ms);
}
priv->wdev.min_timeout = 1;
priv->wdev.timeout = DEFAULT_TIMEOUT;
@ -176,7 +227,8 @@ static int rza_wdt_probe(struct platform_device *pdev)
}
static const struct of_device_id rza_wdt_of_match[] = {
{ .compatible = "renesas,rza-wdt", },
{ .compatible = "renesas,r7s9210-wdt", .data = (void *)CKS_4BIT, },
{ .compatible = "renesas,rza-wdt", .data = (void *)CKS_3BIT, },
{ /* sentinel */ }
};
MODULE_DEVICE_TABLE(of, rza_wdt_of_match);