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

Commit Message

Biju Das Sept. 2, 2019, 3:57 p.m. UTC

From: Yoshihiro Shimoda <[e-mail]>

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 <[e-mail]>
Reviewed-by: Geert Uytterhoeven <[e-mail]>
Reviewed-by: Wolfram Sang <[e-mail]>
Reviewed-by: Niklas Söderlund <[e-mail]>
Reviewed-by: Simon Horman <[e-mail]>
Reviewed-by: Guenter Roeck <[e-mail]>
Signed-off-by: Guenter Roeck <[e-mail]>
Signed-off-by: Wim Van Sebroeck <[e-mail]>
Signed-off-by: Fabrizio Castro <[e-mail]>
---
 drivers/watchdog/renesas_wdt.c | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

Patch

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;