[PATCH 4.19.y-cip 06/22] watchdog: renesas_wdt: Add a few cycles delay


Biju Das <biju.das@...>
 

From: Yoshihiro Shimoda <yoshihiro.shimoda.uh@...>

commit b836005b4f95cccdc1f53849a31cac2dc375f4b7 upstream.

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@...>
Reviewed-by: Geert Uytterhoeven <geert+renesas@...>
Reviewed-by: Wolfram Sang <wsa+renesas@...>
Reviewed-by: Niklas Söderlund <niklas.soderlund+renesas@...>
Reviewed-by: Simon Horman <horms+renesas@...>
Reviewed-by: Guenter Roeck <linux@...>
Signed-off-by: Guenter Roeck <linux@...>
Signed-off-by: Wim Van Sebroeck <wim@...>
Signed-off-by: Fabrizio Castro <fabrizio.castro@...>
---
drivers/watchdog/renesas_wdt.c | 14 ++++++++++++++
1 file changed, 14 insertions(+)

diff --git a/drivers/watchdog/renesas_wdt.c b/drivers/watchdog/renesas_wdt.c
index 450e517..2496397 100644
--- a/drivers/watchdog/renesas_wdt.c
+++ b/drivers/watchdog/renesas_wdt.c
@@ -10,6 +10,7 @@
*/
#include <linux/bitops.h>
#include <linux/clk.h>
+#include <linux/delay.h>
#include <linux/io.h>
#include <linux/kernel.h>
#include <linux/module.h>
@@ -73,6 +74,15 @@ 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);
@@ -83,6 +93,8 @@ 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);
@@ -101,6 +113,8 @@ 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;
--
2.7.4

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