diff options
Diffstat (limited to 'drivers/watchdog/sama5d4_wdt.c')
| -rw-r--r-- | drivers/watchdog/sama5d4_wdt.c | 33 |
1 files changed, 29 insertions, 4 deletions
diff --git a/drivers/watchdog/sama5d4_wdt.c b/drivers/watchdog/sama5d4_wdt.c index 5cee20caca78..362fd229786d 100644 --- a/drivers/watchdog/sama5d4_wdt.c +++ b/drivers/watchdog/sama5d4_wdt.c @@ -6,6 +6,7 @@ * Licensed under GPLv2. */ +#include <linux/delay.h> #include <linux/interrupt.h> #include <linux/io.h> #include <linux/kernel.h> @@ -29,6 +30,7 @@ struct sama5d4_wdt { struct watchdog_device wdd; void __iomem *reg_base; u32 mr; + unsigned long last_ping; }; static int wdt_timeout = WDT_DEFAULT_TIMEOUT; @@ -49,8 +51,29 @@ MODULE_PARM_DESC(nowayout, #define wdt_read(wdt, field) \ readl_relaxed((wdt)->reg_base + (field)) -#define wdt_write(wtd, field, val) \ - writel_relaxed((val), (wdt)->reg_base + (field)) +/* 4 slow clock periods is 4/32768 = 122.07µs*/ +#define WDT_DELAY usecs_to_jiffies(123) + +static void wdt_write(struct sama5d4_wdt *wdt, u32 field, u32 val) +{ + /* + * WDT_CR and WDT_MR must not be modified within three slow clock + * periods following a restart of the watchdog performed by a write + * access in WDT_CR. + */ + while (time_before(jiffies, wdt->last_ping + WDT_DELAY)) + usleep_range(30, 125); + writel_relaxed(val, wdt->reg_base + field); + wdt->last_ping = jiffies; +} + +static void wdt_write_nosleep(struct sama5d4_wdt *wdt, u32 field, u32 val) +{ + if (time_before(jiffies, wdt->last_ping + WDT_DELAY)) + udelay(123); + writel_relaxed(val, wdt->reg_base + field); + wdt->last_ping = jiffies; +} static int sama5d4_wdt_start(struct watchdog_device *wdd) { @@ -164,11 +187,12 @@ static int sama5d4_wdt_init(struct sama5d4_wdt *wdt) * Else, we have to disable it properly. */ if (wdt_enabled) { - wdt_write(wdt, AT91_WDT_MR, wdt->mr); + wdt_write_nosleep(wdt, AT91_WDT_MR, wdt->mr); } else { reg = wdt_read(wdt, AT91_WDT_MR); if (!(reg & AT91_WDT_WDDIS)) - wdt_write(wdt, AT91_WDT_MR, reg | AT91_WDT_WDDIS); + wdt_write_nosleep(wdt, AT91_WDT_MR, + reg | AT91_WDT_WDDIS); } return 0; } @@ -193,6 +217,7 @@ static int sama5d4_wdt_probe(struct platform_device *pdev) wdd->ops = &sama5d4_wdt_ops; wdd->min_timeout = MIN_WDT_TIMEOUT; wdd->max_timeout = MAX_WDT_TIMEOUT; + wdt->last_ping = jiffies; watchdog_set_drvdata(wdd, wdt); |