watchdog: renesas_wdt: Add a few cycles delay (b836005b) · Commits · 戴 / test

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:

Wim Van Sebroeck <wim@linux-watchdog.org>

drivers/watchdog/renesas_wdt.c

+14 −0

Original line number	Diff line number	Diff line
		@@ -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;

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