On 03/09/2018 07:46 PM, Brian Norris wrote:
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@xxxxxxxxxxxx>
Reviewed-by: Guenter Roeck <linux@xxxxxxxxxxxx>
---
v2:
* factor out helper
* handle both start() and restart() cases
* note the RESP_MODE handling in commit message
---
drivers/watchdog/dw_wdt.c | 23 +++++++++++++++--------
1 file changed, 15 insertions(+), 8 deletions(-)
diff --git a/drivers/watchdog/dw_wdt.c b/drivers/watchdog/dw_wdt.c
index c2f4ff516230..918357bccf5e 100644
--- 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 watchdog_device *wdd, unsigned int top_s)
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 watchdog_device *wdd,
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);
--
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