From 882dec1ff125e9020157d27672ec11c2fdfb82c2 Mon Sep 17 00:00:00 2001 From: Javier Martinez Canillas Date: Tue, 1 Mar 2016 13:45:17 -0300 Subject: [PATCH] watchdog: s3c2410_wdt: Add max and min timeout values The watchdog maximum timeout value is determined by the number of bits for the interval timer counter, its source clock frequency, the number of bits of the prescaler and maximum divider value. This can be calculated with the following equation: max_timeout = counter / (freq / (max_prescale + 1) / max_divider) Setting a maximum timeout value will allow the watchdog core to refuse user-space calls to the WDIOC_SETTIMEOUT ioctl that sets not supported timeout values. For example, systemd tries to set a timeout of 10 minutes on reboot to ensure that the machine will be rebooted even if a reboot failed. This leads to the following error message on an Exynos5422 Odroid XU4 board: [ 147.986045] s3c2410-wdt 101d0000.watchdog: timeout 600 too big Reported-by: Krzysztof Kozlowski Signed-off-by: Javier Martinez Canillas Reviewed-by: Krzysztof Kozlowski Signed-off-by: Guenter Roeck Signed-off-by: Wim Van Sebroeck --- drivers/watchdog/s3c2410_wdt.c | 16 ++++++++++++++++ 1 file changed, 16 insertions(+) diff --git a/drivers/watchdog/s3c2410_wdt.c b/drivers/watchdog/s3c2410_wdt.c index d57f19b5077f..59e95762a6de 100644 --- a/drivers/watchdog/s3c2410_wdt.c +++ b/drivers/watchdog/s3c2410_wdt.c @@ -47,6 +47,8 @@ #define S3C2410_WTDAT 0x04 #define S3C2410_WTCNT 0x08 +#define S3C2410_WTCNT_MAXCNT 0xffff + #define S3C2410_WTCON_RSTEN (1 << 0) #define S3C2410_WTCON_INTEN (1 << 2) #define S3C2410_WTCON_ENABLE (1 << 5) @@ -56,8 +58,11 @@ #define S3C2410_WTCON_DIV64 (2 << 3) #define S3C2410_WTCON_DIV128 (3 << 3) +#define S3C2410_WTCON_MAXDIV 0x80 + #define S3C2410_WTCON_PRESCALE(x) ((x) << 8) #define S3C2410_WTCON_PRESCALE_MASK (0xff << 8) +#define S3C2410_WTCON_PRESCALE_MAX 0xff #define CONFIG_S3C2410_WATCHDOG_ATBOOT (0) #define CONFIG_S3C2410_WATCHDOG_DEFAULT_TIME (15) @@ -198,6 +203,14 @@ do { \ /* functions */ +static inline unsigned int s3c2410wdt_max_timeout(struct clk *clock) +{ + unsigned long freq = clk_get_rate(clock); + + return S3C2410_WTCNT_MAXCNT / (freq / (S3C2410_WTCON_PRESCALE_MAX + 1) + / S3C2410_WTCON_MAXDIV); +} + static inline struct s3c2410_wdt *freq_to_wdt(struct notifier_block *nb) { return container_of(nb, struct s3c2410_wdt, freq_transition); @@ -568,6 +581,9 @@ static int s3c2410wdt_probe(struct platform_device *pdev) return ret; } + wdt->wdt_device.min_timeout = 1; + wdt->wdt_device.max_timeout = s3c2410wdt_max_timeout(wdt->clock); + ret = s3c2410wdt_cpufreq_register(wdt); if (ret < 0) { dev_err(dev, "failed to register cpufreq\n"); -- 2.20.1