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watchdog: renesas_wdt: Add a few cycles delay 

According to the hardware manual of R-Car Gen2 and Gen3,
software should wait a few RLCK cycles as following:
 - Delay 2 cycles before setting watchdog counter.
 - Delay 3 cycles before disabling module clock.

So, this patch adds such delays.

Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Reviewed-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>
Reviewed-by: Simon Horman <horms+renesas@verge.net.au>
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>
alistair/sunxi64-5.4-dsi
Yoshihiro Shimoda 2019-06-05 14:04:00 +09:00 committed by Wim Van Sebroeck
parent 1a4aaf9f11
commit b836005b4f
1 changed files with 14 additions and 0 deletions
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14
drivers/watchdog/renesas_wdt.c
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@ -7,6 +7,7 @@
*/
#include <linux/bitops.h>
#include <linux/clk.h>
#include <linux/delay.h>
#include <linux/io.h>
#include <linux/kernel.h>
#include <linux/module.h>
@ -70,6 +71,15 @@ static int rwdt_init_timeout(struct watchdog_device *wdev)
return 0;
}
static void rwdt_wait_cycles(struct rwdt_priv *priv, unsigned int cycles)
{
unsigned int delay;
delay = DIV_ROUND_UP(cycles * 1000000, priv->clk_rate);
usleep_range(delay, 2 * delay);
}
static int rwdt_start(struct watchdog_device *wdev)
{
struct rwdt_priv *priv = watchdog_get_drvdata(wdev);
@ -80,6 +90,8 @@ static int rwdt_start(struct watchdog_device *wdev)
/* Stop the timer before we modify any register */
val = readb_relaxed(priv->base + RWTCSRA) & ~RWTCSRA_TME;
rwdt_write(priv, val, RWTCSRA);
/* Delay 2 cycles before setting watchdog counter */
rwdt_wait_cycles(priv, 2);
rwdt_init_timeout(wdev);
rwdt_write(priv, priv->cks, RWTCSRA);
@ -98,6 +110,8 @@ static int rwdt_stop(struct watchdog_device *wdev)
struct rwdt_priv *priv = watchdog_get_drvdata(wdev);
rwdt_write(priv, priv->cks, RWTCSRA);
/* Delay 3 cycles before disabling module clock */
rwdt_wait_cycles(priv, 3);
pm_runtime_put(wdev->parent);
return 0;