Re: [PATCH v3 2/4] watchdog: da9062: reset board on watchdog timeout
From: Andrej Picej
Date: Thu Dec 02 2021 - 02:43:32 EST
Hi Christoph,
On 1. 12. 21 15:11, Christoph Niedermaier wrote:
From: Andrej Picej
Sent: Wednesday, December 1, 2021 9:15 AM
Implement a method to change watchdog timeout configuration based on DT
binding ("dlg,wdt-sd"). There is a possibility to change the bahaviour
of watchdog reset. Setting WATCHDOG_SD bit enables SHUTDOWN mode, and
clearing it enables POWERDOWN mode on watchdog timeout.
If no DT binding is specified the WATCHDOG_SD bit stays in default
configuration, not breaking behaviour of devices which might depend on
default fuse configuration.
Note: This patch requires that the config register CONFIG_I is
configured as writable in the da9062 multi function device.
Signed-off-by: Andrej Picej <andrej.picej@xxxxxxxxx>
---
Changes in v3:
- no changes
Changes in v2:
- don't force the "reset" for all da9062-watchdog users, instead add DT
binding where the behavior can be selected
---
drivers/watchdog/da9062_wdt.c | 25 +++++++++++++++++++++++++
1 file changed, 25 insertions(+)
diff --git a/drivers/watchdog/da9062_wdt.c b/drivers/watchdog/da9062_wdt.c
index f02cbd530538..e342e9e50cb1 100644
--- a/drivers/watchdog/da9062_wdt.c
+++ b/drivers/watchdog/da9062_wdt.c
@@ -85,8 +85,33 @@ static int da9062_wdt_start(struct watchdog_device *wdd)
{
struct da9062_watchdog *wdt = watchdog_get_drvdata(wdd);
unsigned int selector;
+ unsigned int mask;
+ u32 val;
int ret;
+ /* Configure what happens on watchdog timeout. Can be specified with
+ * "dlg,wdt-sd" dt-binding (0 -> POWERDOWN, 1 -> SHUTDOWN).
+ * If "dlg,wdt-sd" dt-binding is NOT set use the default.
+ */
+ ret = device_property_read_u32(wdd->parent, "dlg,wdt-sd", &val);
+ if (!ret) {
+ if (val)
+ /* Use da9062's SHUTDOWN mode */
+ mask = DA9062AA_WATCHDOG_SD_MASK;
+ else
+ /* Use da9062's POWERDOWN mode. */
+ mask = 0x0;
+
+ ret = regmap_update_bits(wdt->hw->regmap,
+ DA9062AA_CONFIG_I,
+ DA9062AA_WATCHDOG_SD_MASK,
+ mask);
+
+ if (ret)
+ dev_err(wdt->hw->dev, "failed to set wdt reset mode:
%d\n",
+ ret);
+ }
+
selector = da9062_wdt_timeout_to_sel(wdt->wdtdev.timeout);
ret = da9062_wdt_update_timeout_register(wdt, selector);
if (ret)
--
2.25.1
I have a question how to correctly restart the system after
watchdog timeout.
If I understand it correct after watchdog timeout the system
restarts only if WATCHDOG_SD (Bit 3) in register CONFIG_I is
set.
What is the difference if WATCHDOG_SD isn't set, but WAKE_UP
(Bit 2) in register CONTROL_F is set? From outside on my
system I observe the same behavior. After watchdog timeout
my system restarts. So where are the differences?
It would be nice if you could answer this question, as you
certainly know this chip very well.
To be honest I don't really know the chip that well, I'm just trying to
add this feature and hopefully help others if they run into the same
problem. I think @Adam will be more helpful here.
But from quick look at da9062 datasheet, mainly chapter "8.8 Power
Modes" I see next main differences:
- setting WATCHDOG_SD enables SHUTDOWN sequence when the watchdog
timeout is triggered. This puts the chip (da9062) in RESET mode.
Taken from DA9062 datasheet:
In RESET mode, the internal supplies, and LDO1 (if configured as an always-on supply) are enabled.
All other DA9062 supplies are disabled.
DA9062 is in RESET mode whenever a complete application shutdown is required
The DA9062’s register configuration will be re-loaded from OTP when leaving the RESET mode
- if you set the WAKE_UP bit than the chip enters POWERDOWN mode on
watchdog timeout. I understand the POWERDOWN mode as a not that "deep"
mode as a RESET mode Device will go from RESET mode to POWERDOWN mode in
the sequence of powering-up.
The above explanation is just my understanding after quick look, @Adam
please correct me if I'm talking nonsense.
Please have a look at the DA9062 datasheet for more information. Sorry,
that I can't be more helpful here.
Best regards,
Andrej