4.16-stable review patch. If anyone has any objections, please let me know.
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From: Brian Norris briannorris@chromium.org
[ Upstream commit a81abbb412341e9e3b2d42ed7d310cf71fbb84a8 ]
RK3399 has rst_pulse_length in CONTROL_REG[4:2], determining the length of pulse to issue for system reset. We shouldn't clobber this value, because that might make the system reset ineffective. On RK3399, we're seeing that a value of 000b (meaning 2 cycles) yields an unreliable (partial?) reset, and so we only fully reset after the watchdog fires a second time. If we retain the system default (010b, or 8 clock cycles), then the watchdog reset is much more reliable.
Read-modify-write retains the system value and improves reset reliability.
It seems we were intentionally clobbering the response mode previously, to ensure we performed a system reset (we don't support an interrupt notification), so retain that explicitly.
Signed-off-by: Brian Norris briannorris@chromium.org Reviewed-by: Guenter Roeck linux@roeck-us.net Signed-off-by: Guenter Roeck linux@roeck-us.net Signed-off-by: Wim Van Sebroeck wim@iguana.be Signed-off-by: Sasha Levin alexander.levin@microsoft.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/watchdog/dw_wdt.c | 23 +++++++++++++++-------- 1 file changed, 15 insertions(+), 8 deletions(-)
--- a/drivers/watchdog/dw_wdt.c +++ b/drivers/watchdog/dw_wdt.c @@ -34,6 +34,7 @@
#define WDOG_CONTROL_REG_OFFSET 0x00 #define WDOG_CONTROL_REG_WDT_EN_MASK 0x01 +#define WDOG_CONTROL_REG_RESP_MODE_MASK 0x02 #define WDOG_TIMEOUT_RANGE_REG_OFFSET 0x04 #define WDOG_TIMEOUT_RANGE_TOPINIT_SHIFT 4 #define WDOG_CURRENT_COUNT_REG_OFFSET 0x08 @@ -121,14 +122,23 @@ static int dw_wdt_set_timeout(struct wat return 0; }
+static void dw_wdt_arm_system_reset(struct dw_wdt *dw_wdt) +{ + u32 val = readl(dw_wdt->regs + WDOG_CONTROL_REG_OFFSET); + + /* Disable interrupt mode; always perform system reset. */ + val &= ~WDOG_CONTROL_REG_RESP_MODE_MASK; + /* Enable watchdog. */ + val |= WDOG_CONTROL_REG_WDT_EN_MASK; + writel(val, dw_wdt->regs + WDOG_CONTROL_REG_OFFSET); +} + static int dw_wdt_start(struct watchdog_device *wdd) { struct dw_wdt *dw_wdt = to_dw_wdt(wdd);
dw_wdt_set_timeout(wdd, wdd->timeout); - - writel(WDOG_CONTROL_REG_WDT_EN_MASK, - dw_wdt->regs + WDOG_CONTROL_REG_OFFSET); + dw_wdt_arm_system_reset(dw_wdt);
return 0; } @@ -152,16 +162,13 @@ static int dw_wdt_restart(struct watchdo unsigned long action, void *data) { struct dw_wdt *dw_wdt = to_dw_wdt(wdd); - u32 val;
writel(0, dw_wdt->regs + WDOG_TIMEOUT_RANGE_REG_OFFSET); - val = readl(dw_wdt->regs + WDOG_CONTROL_REG_OFFSET); - if (val & WDOG_CONTROL_REG_WDT_EN_MASK) + if (dw_wdt_is_enabled(dw_wdt)) writel(WDOG_COUNTER_RESTART_KICK_VALUE, dw_wdt->regs + WDOG_COUNTER_RESTART_REG_OFFSET); else - writel(WDOG_CONTROL_REG_WDT_EN_MASK, - dw_wdt->regs + WDOG_CONTROL_REG_OFFSET); + dw_wdt_arm_system_reset(dw_wdt);
/* wait for reset to assert... */ mdelay(500);