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 <[email protected]> Reviewed-by: Geert Uytterhoeven <[email protected]> Reviewed-by: Wolfram Sang <[email protected]> Reviewed-by: Niklas Söderlund <[email protected]> --- Changes from v2 (https://patchwork.kernel.org/patch/10972721/): - Rename the wait function name. - Rename the variable name in the wait function. - Change variable type. - Add Wolfram-san and Niklas-san's Reviewed-by. Changes from v1 (https://patchwork.kernel.org/patch/10972641/): - Change formula to improve accuracy. - Add Geert-san's Reviewed-by. 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 565dbc1..0cfc0e9 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; -- 2.7.4
