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authorYoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>2019-06-05 14:04:00 +0900
committerWim Van Sebroeck <wim@linux-watchdog.org>2019-07-08 19:39:44 +0200
commitb836005b4f95cccdc1f53849a31cac2dc375f4b7 (patch)
tree38382bf14eb80c8fb4de63faf13e7a6fc1ff5bb0 /drivers/watchdog/renesas_wdt.c
parent1a4aaf9f11f9937e93fe9907e6c2320a10a9f269 (diff)
downloadlinux-b836005b4f95cccdc1f53849a31cac2dc375f4b7.tar.bz2
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>
Diffstat (limited to 'drivers/watchdog/renesas_wdt.c')
-rw-r--r--drivers/watchdog/renesas_wdt.c14
1 files changed, 14 insertions, 0 deletions
diff --git a/drivers/watchdog/renesas_wdt.c b/drivers/watchdog/renesas_wdt.c
index d8ac2299400b..00662a8e039c 100644
--- a/drivers/watchdog/renesas_wdt.c
+++ b/drivers/watchdog/renesas_wdt.c
@@ -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;