This patch series enhances the support for the SP805 watchdog timer.
First of all, 'timeout-sec' devicetree property is added. In addition,
support is also added to allow the driver to reset the watchdog if it
has been detected that watchdot has been started in the bootloader. In
this case, the driver will initiate the ping service from the kernel
watchdog subsystem, before a user mode daemon takes over. This series
also enables SP805 in the default ARM64 defconfig
This patch series is based off v4.17-rc5 and is available on GIHUB:
repo: https://github.com/Broadcom/arm64-linux.git
branch: sp805-wdt-v1
Ray Jui (5):
Documentation: DT: Add optional 'timeout-sec' property for sp805
watchdog: sp805: add 'timeout-sec' DT property support
watchdog: sp805: set WDOG_HW_RUNNING when appropriate
arm64: dt: set initial SR watchdog timeout to 60 seconds
arm64: defconfig: add CONFIG_ARM_SP805_WATCHDOG
.../devicetree/bindings/watchdog/sp805-wdt.txt | 2 ++
.../arm64/boot/dts/broadcom/stingray/stingray.dtsi | 1 +
arch/arm64/configs/defconfig | 1 +
drivers/watchdog/sp805_wdt.c | 31 +++++++++++++++++++++-
4 files changed, 34 insertions(+), 1 deletion(-)
--
2.1.4
Enable the SP805 watchdog timer
Signed-off-by: Ray Jui <[email protected]>
---
arch/arm64/configs/defconfig | 1 +
1 file changed, 1 insertion(+)
diff --git a/arch/arm64/configs/defconfig b/arch/arm64/configs/defconfig
index ecf6137..3fe5eb5 100644
--- a/arch/arm64/configs/defconfig
+++ b/arch/arm64/configs/defconfig
@@ -351,6 +351,7 @@ CONFIG_ROCKCHIP_THERMAL=m
CONFIG_TEGRA_BPMP_THERMAL=m
CONFIG_UNIPHIER_THERMAL=y
CONFIG_WATCHDOG=y
+CONFIG_ARM_SP805_WATCHDOG=y
CONFIG_S3C2410_WATCHDOG=y
CONFIG_MESON_GXBB_WATCHDOG=m
CONFIG_MESON_WATCHDOG=m
--
2.1.4
Set initial Stingray watchdog timeout to 60 seconds
By the time when the userspace watchdog daemon is ready and taking
control over, the watchdog timeout will then be reset to what's
configured in the daemon
Signed-off-by: Ray Jui <[email protected]>
Reviewed-by: Vladimir Olovyannikov <[email protected]>
Reviewed-by: Scott Branden <[email protected]>
---
arch/arm64/boot/dts/broadcom/stingray/stingray.dtsi | 1 +
1 file changed, 1 insertion(+)
diff --git a/arch/arm64/boot/dts/broadcom/stingray/stingray.dtsi b/arch/arm64/boot/dts/broadcom/stingray/stingray.dtsi
index 99aaff0..1e1cf49 100644
--- a/arch/arm64/boot/dts/broadcom/stingray/stingray.dtsi
+++ b/arch/arm64/boot/dts/broadcom/stingray/stingray.dtsi
@@ -420,6 +420,7 @@
interrupts = <GIC_SPI 189 IRQ_TYPE_LEVEL_HIGH>;
clocks = <&hsls_25m_div2_clk>, <&hsls_div4_clk>;
clock-names = "wdogclk", "apb_pclk";
+ timeout-sec = <60>;
};
gpio_hsls: gpio@d0000 {
--
2.1.4
If the watchdog hardware is already enabled during the boot process,
when the Linux watchdog driver loads, it should reset the watchdog and
tell the watchdog framework. As a result, ping can be generated from
the watchdog framework, until the userspace watchdog daemon takes over
control
Signed-off-by: Ray Jui <[email protected]>
Reviewed-by: Vladimir Olovyannikov <[email protected]>
Reviewed-by: Scott Branden <[email protected]>
---
drivers/watchdog/sp805_wdt.c | 22 ++++++++++++++++++++++
1 file changed, 22 insertions(+)
diff --git a/drivers/watchdog/sp805_wdt.c b/drivers/watchdog/sp805_wdt.c
index 1484609..408ffbe 100644
--- a/drivers/watchdog/sp805_wdt.c
+++ b/drivers/watchdog/sp805_wdt.c
@@ -42,6 +42,7 @@
/* control register masks */
#define INT_ENABLE (1 << 0)
#define RESET_ENABLE (1 << 1)
+ #define ENABLE_MASK (INT_ENABLE | RESET_ENABLE)
#define WDTINTCLR 0x00C
#define WDTRIS 0x010
#define WDTMIS 0x014
@@ -74,6 +75,18 @@ module_param(nowayout, bool, 0);
MODULE_PARM_DESC(nowayout,
"Set to 1 to keep watchdog running after device release");
+/* returns true if wdt is running; otherwise returns false */
+static bool wdt_is_running(struct watchdog_device *wdd)
+{
+ struct sp805_wdt *wdt = watchdog_get_drvdata(wdd);
+
+ if ((readl_relaxed(wdt->base + WDTCONTROL) & ENABLE_MASK) ==
+ ENABLE_MASK)
+ return true;
+ else
+ return false;
+}
+
/* This routine finds load value that will reset system in required timout */
static int wdt_setload(struct watchdog_device *wdd, unsigned int timeout)
{
@@ -239,6 +252,15 @@ sp805_wdt_probe(struct amba_device *adev, const struct amba_id *id)
watchdog_init_timeout(&wdt->wdd, 0, &adev->dev);
wdt_setload(&wdt->wdd, wdt->wdd.timeout);
+ /*
+ * If HW is already running, enable/reset the wdt and set the running
+ * bit to tell the wdt subsystem
+ */
+ if (wdt_is_running(&wdt->wdd)) {
+ wdt_enable(&wdt->wdd);
+ set_bit(WDOG_HW_RUNNING, &wdt->wdd.status);
+ }
+
ret = watchdog_register_device(&wdt->wdd);
if (ret) {
dev_err(&adev->dev, "watchdog_register_device() failed: %d\n",
--
2.1.4
Add support for optional devicetree property 'timeout-sec'.
'timeout-sec' is used in the driver if specified in devicetree.
Otherwise, fall back to driver default, i.e., 60 seconds
Signed-off-by: Ray Jui <[email protected]>
Reviewed-by: Scott Branden <[email protected]>
---
drivers/watchdog/sp805_wdt.c | 9 ++++++++-
1 file changed, 8 insertions(+), 1 deletion(-)
diff --git a/drivers/watchdog/sp805_wdt.c b/drivers/watchdog/sp805_wdt.c
index 03805bc..1484609 100644
--- a/drivers/watchdog/sp805_wdt.c
+++ b/drivers/watchdog/sp805_wdt.c
@@ -230,7 +230,14 @@ sp805_wdt_probe(struct amba_device *adev, const struct amba_id *id)
spin_lock_init(&wdt->lock);
watchdog_set_nowayout(&wdt->wdd, nowayout);
watchdog_set_drvdata(&wdt->wdd, wdt);
- wdt_setload(&wdt->wdd, DEFAULT_TIMEOUT);
+
+ /*
+ * If 'timeout-sec' devicetree property is specified, use that.
+ * Otherwise, use DEFAULT_TIMEOUT
+ */
+ wdt->wdd.timeout = DEFAULT_TIMEOUT;
+ watchdog_init_timeout(&wdt->wdd, 0, &adev->dev);
+ wdt_setload(&wdt->wdd, wdt->wdd.timeout);
ret = watchdog_register_device(&wdt->wdd);
if (ret) {
--
2.1.4
Update the SP805 binding document to add optional 'timeout-sec'
devicetree property
Signed-off-by: Ray Jui <[email protected]>
Reviewed-by: Scott Branden <[email protected]>
---
Documentation/devicetree/bindings/watchdog/sp805-wdt.txt | 2 ++
1 file changed, 2 insertions(+)
diff --git a/Documentation/devicetree/bindings/watchdog/sp805-wdt.txt b/Documentation/devicetree/bindings/watchdog/sp805-wdt.txt
index edc4f0e..f898a86 100644
--- a/Documentation/devicetree/bindings/watchdog/sp805-wdt.txt
+++ b/Documentation/devicetree/bindings/watchdog/sp805-wdt.txt
@@ -19,6 +19,8 @@ Required properties:
Optional properties:
- interrupts : Should specify WDT interrupt number.
+- timeout-sec : Should specify default WDT timeout in seconds. If unset, the
+ default timeout is 30 seconds
Examples:
--
2.1.4
On Tue, May 22, 2018 at 11:47:18AM -0700, Ray Jui wrote:
> If the watchdog hardware is already enabled during the boot process,
> when the Linux watchdog driver loads, it should reset the watchdog and
> tell the watchdog framework. As a result, ping can be generated from
> the watchdog framework, until the userspace watchdog daemon takes over
> control
>
> Signed-off-by: Ray Jui <[email protected]>
> Reviewed-by: Vladimir Olovyannikov <[email protected]>
> Reviewed-by: Scott Branden <[email protected]>
> ---
> drivers/watchdog/sp805_wdt.c | 22 ++++++++++++++++++++++
> 1 file changed, 22 insertions(+)
>
> diff --git a/drivers/watchdog/sp805_wdt.c b/drivers/watchdog/sp805_wdt.c
> index 1484609..408ffbe 100644
> --- a/drivers/watchdog/sp805_wdt.c
> +++ b/drivers/watchdog/sp805_wdt.c
> @@ -42,6 +42,7 @@
> /* control register masks */
> #define INT_ENABLE (1 << 0)
> #define RESET_ENABLE (1 << 1)
> + #define ENABLE_MASK (INT_ENABLE | RESET_ENABLE)
> #define WDTINTCLR 0x00C
> #define WDTRIS 0x010
> #define WDTMIS 0x014
> @@ -74,6 +75,18 @@ module_param(nowayout, bool, 0);
> MODULE_PARM_DESC(nowayout,
> "Set to 1 to keep watchdog running after device release");
>
> +/* returns true if wdt is running; otherwise returns false */
> +static bool wdt_is_running(struct watchdog_device *wdd)
> +{
> + struct sp805_wdt *wdt = watchdog_get_drvdata(wdd);
> +
> + if ((readl_relaxed(wdt->base + WDTCONTROL) & ENABLE_MASK) ==
> + ENABLE_MASK)
> + return true;
> + else
> + return false;
return !!(readl_relaxed(wdt->base + WDTCONTROL) & ENABLE_MASK));
> +}
> +
> /* This routine finds load value that will reset system in required timout */
> static int wdt_setload(struct watchdog_device *wdd, unsigned int timeout)
> {
> @@ -239,6 +252,15 @@ sp805_wdt_probe(struct amba_device *adev, const struct amba_id *id)
> watchdog_init_timeout(&wdt->wdd, 0, &adev->dev);
> wdt_setload(&wdt->wdd, wdt->wdd.timeout);
>
> + /*
> + * If HW is already running, enable/reset the wdt and set the running
> + * bit to tell the wdt subsystem
> + */
> + if (wdt_is_running(&wdt->wdd)) {
> + wdt_enable(&wdt->wdd);
> + set_bit(WDOG_HW_RUNNING, &wdt->wdd.status);
> + }
> +
> ret = watchdog_register_device(&wdt->wdd);
> if (ret) {
> dev_err(&adev->dev, "watchdog_register_device() failed: %d\n",
> --
> 2.1.4
>
On Tue, May 22, 2018 at 11:47:16AM -0700, Ray Jui wrote:
> Update the SP805 binding document to add optional 'timeout-sec'
> devicetree property
>
> Signed-off-by: Ray Jui <[email protected]>
> Reviewed-by: Scott Branden <[email protected]>
Reviewed-by: Guenter Roeck <[email protected]>
> ---
> Documentation/devicetree/bindings/watchdog/sp805-wdt.txt | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/Documentation/devicetree/bindings/watchdog/sp805-wdt.txt b/Documentation/devicetree/bindings/watchdog/sp805-wdt.txt
> index edc4f0e..f898a86 100644
> --- a/Documentation/devicetree/bindings/watchdog/sp805-wdt.txt
> +++ b/Documentation/devicetree/bindings/watchdog/sp805-wdt.txt
> @@ -19,6 +19,8 @@ Required properties:
>
> Optional properties:
> - interrupts : Should specify WDT interrupt number.
> +- timeout-sec : Should specify default WDT timeout in seconds. If unset, the
> + default timeout is 30 seconds
>
> Examples:
>
> --
> 2.1.4
>
On Tue, May 22, 2018 at 11:47:17AM -0700, Ray Jui wrote:
> Add support for optional devicetree property 'timeout-sec'.
> 'timeout-sec' is used in the driver if specified in devicetree.
> Otherwise, fall back to driver default, i.e., 60 seconds
>
> Signed-off-by: Ray Jui <[email protected]>
> Reviewed-by: Scott Branden <[email protected]>
Reviewed-by: Guenter Roeck <[email protected]>
> ---
> drivers/watchdog/sp805_wdt.c | 9 ++++++++-
> 1 file changed, 8 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/watchdog/sp805_wdt.c b/drivers/watchdog/sp805_wdt.c
> index 03805bc..1484609 100644
> --- a/drivers/watchdog/sp805_wdt.c
> +++ b/drivers/watchdog/sp805_wdt.c
> @@ -230,7 +230,14 @@ sp805_wdt_probe(struct amba_device *adev, const struct amba_id *id)
> spin_lock_init(&wdt->lock);
> watchdog_set_nowayout(&wdt->wdd, nowayout);
> watchdog_set_drvdata(&wdt->wdd, wdt);
> - wdt_setload(&wdt->wdd, DEFAULT_TIMEOUT);
> +
> + /*
> + * If 'timeout-sec' devicetree property is specified, use that.
> + * Otherwise, use DEFAULT_TIMEOUT
> + */
> + wdt->wdd.timeout = DEFAULT_TIMEOUT;
> + watchdog_init_timeout(&wdt->wdd, 0, &adev->dev);
> + wdt_setload(&wdt->wdd, wdt->wdd.timeout);
>
> ret = watchdog_register_device(&wdt->wdd);
> if (ret) {
> --
> 2.1.4
>
Hi Guenter,
On 5/22/2018 1:54 PM, Guenter Roeck wrote:
> On Tue, May 22, 2018 at 11:47:18AM -0700, Ray Jui wrote:
>> If the watchdog hardware is already enabled during the boot process,
>> when the Linux watchdog driver loads, it should reset the watchdog and
>> tell the watchdog framework. As a result, ping can be generated from
>> the watchdog framework, until the userspace watchdog daemon takes over
>> control
>>
>> Signed-off-by: Ray Jui <[email protected]>
>> Reviewed-by: Vladimir Olovyannikov <[email protected]>
>> Reviewed-by: Scott Branden <[email protected]>
>> ---
>> drivers/watchdog/sp805_wdt.c | 22 ++++++++++++++++++++++
>> 1 file changed, 22 insertions(+)
>>
>> diff --git a/drivers/watchdog/sp805_wdt.c b/drivers/watchdog/sp805_wdt.c
>> index 1484609..408ffbe 100644
>> --- a/drivers/watchdog/sp805_wdt.c
>> +++ b/drivers/watchdog/sp805_wdt.c
>> @@ -42,6 +42,7 @@
>> /* control register masks */
>> #define INT_ENABLE (1 << 0)
>> #define RESET_ENABLE (1 << 1)
>> + #define ENABLE_MASK (INT_ENABLE | RESET_ENABLE)
>> #define WDTINTCLR 0x00C
>> #define WDTRIS 0x010
>> #define WDTMIS 0x014
>> @@ -74,6 +75,18 @@ module_param(nowayout, bool, 0);
>> MODULE_PARM_DESC(nowayout,
>> "Set to 1 to keep watchdog running after device release");
>>
>> +/* returns true if wdt is running; otherwise returns false */
>> +static bool wdt_is_running(struct watchdog_device *wdd)
>> +{
>> + struct sp805_wdt *wdt = watchdog_get_drvdata(wdd);
>> +
>> + if ((readl_relaxed(wdt->base + WDTCONTROL) & ENABLE_MASK) ==
>> + ENABLE_MASK)
>> + return true;
>> + else
>> + return false;
>
> return !!(readl_relaxed(wdt->base + WDTCONTROL) & ENABLE_MASK));
>
Note ENABLE_MASK contains two bits (INT_ENABLE and RESET_ENABLE);
therefore, a simple !!(expression) would not work? That is, the masked
result needs to be compared against the mask again to ensure both bits
are set, right?
Thanks,
Ray
On 18-05-22 04:24 PM, Ray Jui wrote:
> Hi Guenter,
>
> On 5/22/2018 1:54 PM, Guenter Roeck wrote:
>> On Tue, May 22, 2018 at 11:47:18AM -0700, Ray Jui wrote:
>>> If the watchdog hardware is already enabled during the boot process,
>>> when the Linux watchdog driver loads, it should reset the watchdog and
>>> tell the watchdog framework. As a result, ping can be generated from
>>> the watchdog framework, until the userspace watchdog daemon takes over
>>> control
>>>
>>> Signed-off-by: Ray Jui <[email protected]>
>>> Reviewed-by: Vladimir Olovyannikov <[email protected]>
>>> Reviewed-by: Scott Branden <[email protected]>
>>> ---
>>> drivers/watchdog/sp805_wdt.c | 22 ++++++++++++++++++++++
>>> 1 file changed, 22 insertions(+)
>>>
>>> diff --git a/drivers/watchdog/sp805_wdt.c
>>> b/drivers/watchdog/sp805_wdt.c
>>> index 1484609..408ffbe 100644
>>> --- a/drivers/watchdog/sp805_wdt.c
>>> +++ b/drivers/watchdog/sp805_wdt.c
>>> @@ -42,6 +42,7 @@
>>> /* control register masks */
>>> #define INT_ENABLE (1 << 0)
>>> #define RESET_ENABLE (1 << 1)
>>> + #define ENABLE_MASK (INT_ENABLE | RESET_ENABLE)
>>> #define WDTINTCLR 0x00C
>>> #define WDTRIS 0x010
>>> #define WDTMIS 0x014
>>> @@ -74,6 +75,18 @@ module_param(nowayout, bool, 0);
>>> MODULE_PARM_DESC(nowayout,
>>> "Set to 1 to keep watchdog running after device release");
>>> +/* returns true if wdt is running; otherwise returns false */
>>> +static bool wdt_is_running(struct watchdog_device *wdd)
>>> +{
>>> + struct sp805_wdt *wdt = watchdog_get_drvdata(wdd);
>>> +
>>> + if ((readl_relaxed(wdt->base + WDTCONTROL) & ENABLE_MASK) ==
>>> + ENABLE_MASK)
>>> + return true;
>>> + else
>>> + return false;
>>
>> return !!(readl_relaxed(wdt->base + WDTCONTROL) & ENABLE_MASK));
>>
>
> Note ENABLE_MASK contains two bits (INT_ENABLE and RESET_ENABLE);
> therefore, a simple !!(expression) would not work? That is, the masked
> result needs to be compared against the mask again to ensure both bits
> are set, right?
Ray - your original code looks correct to me. Easier to read and less
prone to errors as shown in the attempted translation to a single statement.
>
> Thanks,
>
> Ray
On 22/05/18 19:47, Ray Jui wrote:
> Update the SP805 binding document to add optional 'timeout-sec'
> devicetree property
>
> Signed-off-by: Ray Jui <[email protected]>
> Reviewed-by: Scott Branden <[email protected]>
> ---
> Documentation/devicetree/bindings/watchdog/sp805-wdt.txt | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/Documentation/devicetree/bindings/watchdog/sp805-wdt.txt b/Documentation/devicetree/bindings/watchdog/sp805-wdt.txt
> index edc4f0e..f898a86 100644
> --- a/Documentation/devicetree/bindings/watchdog/sp805-wdt.txt
> +++ b/Documentation/devicetree/bindings/watchdog/sp805-wdt.txt
> @@ -19,6 +19,8 @@ Required properties:
>
> Optional properties:
> - interrupts : Should specify WDT interrupt number.
> +- timeout-sec : Should specify default WDT timeout in seconds. If unset, the
> + default timeout is 30 seconds
According to the SP805 TRM, the default interval is dependent on the
rate of WDOGCLK, but would typically be a lot longer than that :/
On a related note, anyone have any idea why we seem to have two subtly
different SP805 bindings defined?
Robin.
>
> Examples:
>
>
On 23/05/18 08:52, Scott Branden wrote:
>
>
> On 18-05-22 04:24 PM, Ray Jui wrote:
>> Hi Guenter,
>>
>> On 5/22/2018 1:54 PM, Guenter Roeck wrote:
>>> On Tue, May 22, 2018 at 11:47:18AM -0700, Ray Jui wrote:
>>>> If the watchdog hardware is already enabled during the boot process,
>>>> when the Linux watchdog driver loads, it should reset the watchdog and
>>>> tell the watchdog framework. As a result, ping can be generated from
>>>> the watchdog framework, until the userspace watchdog daemon takes over
>>>> control
>>>>
>>>> Signed-off-by: Ray Jui <[email protected]>
>>>> Reviewed-by: Vladimir Olovyannikov <[email protected]>
>>>> Reviewed-by: Scott Branden <[email protected]>
>>>> ---
>>>> drivers/watchdog/sp805_wdt.c | 22 ++++++++++++++++++++++
>>>> 1 file changed, 22 insertions(+)
>>>>
>>>> diff --git a/drivers/watchdog/sp805_wdt.c
>>>> b/drivers/watchdog/sp805_wdt.c
>>>> index 1484609..408ffbe 100644
>>>> --- a/drivers/watchdog/sp805_wdt.c
>>>> +++ b/drivers/watchdog/sp805_wdt.c
>>>> @@ -42,6 +42,7 @@
>>>> /* control register masks */
>>>> #define INT_ENABLE (1 << 0)
>>>> #define RESET_ENABLE (1 << 1)
>>>> + #define ENABLE_MASK (INT_ENABLE | RESET_ENABLE)
>>>> #define WDTINTCLR 0x00C
>>>> #define WDTRIS 0x010
>>>> #define WDTMIS 0x014
>>>> @@ -74,6 +75,18 @@ module_param(nowayout, bool, 0);
>>>> MODULE_PARM_DESC(nowayout,
>>>> "Set to 1 to keep watchdog running after device release");
>>>> +/* returns true if wdt is running; otherwise returns false */
>>>> +static bool wdt_is_running(struct watchdog_device *wdd)
>>>> +{
>>>> + struct sp805_wdt *wdt = watchdog_get_drvdata(wdd);
>>>> +
>>>> + if ((readl_relaxed(wdt->base + WDTCONTROL) & ENABLE_MASK) ==
>>>> + ENABLE_MASK)
>>>> + return true;
>>>> + else
>>>> + return false;
>>>
>>> return !!(readl_relaxed(wdt->base + WDTCONTROL) & ENABLE_MASK));
>>>
>>
>> Note ENABLE_MASK contains two bits (INT_ENABLE and RESET_ENABLE);
>> therefore, a simple !!(expression) would not work? That is, the masked
>> result needs to be compared against the mask again to ensure both bits
>> are set, right?
> Ray - your original code looks correct to me. Easier to read and less
> prone to errors as shown in the attempted translation to a single
> statement.
if (<boolean condition>)
return true;
else
return false;
still looks really dumb, though, and IMO is actually harder to read than
just "return <boolean condition>;" because it forces you to stop and
double-check that the logic is, in fact, only doing the obvious thing.
Robin.
p.s. No thanks for making me remember the mind-boggling horror of
briefly maintaining part of this legacy codebase... :P
$ grep -r '? true : false' --include=*.cpp . | wc -l
951
On 5/23/2018 3:57 AM, Robin Murphy wrote:
> On 22/05/18 19:47, Ray Jui wrote:
>> Update the SP805 binding document to add optional 'timeout-sec'
>> devicetree property
>>
>> Signed-off-by: Ray Jui <[email protected]>
>> Reviewed-by: Scott Branden <[email protected]>
>> ---
>> Documentation/devicetree/bindings/watchdog/sp805-wdt.txt | 2 ++
>> 1 file changed, 2 insertions(+)
>>
>> diff --git a/Documentation/devicetree/bindings/watchdog/sp805-wdt.txt
>> b/Documentation/devicetree/bindings/watchdog/sp805-wdt.txt
>> index edc4f0e..f898a86 100644
>> --- a/Documentation/devicetree/bindings/watchdog/sp805-wdt.txt
>> +++ b/Documentation/devicetree/bindings/watchdog/sp805-wdt.txt
>> @@ -19,6 +19,8 @@ Required properties:
>> Optional properties:
>> - interrupts : Should specify WDT interrupt number.
>> +- timeout-sec : Should specify default WDT timeout in seconds. If
>> unset, the
>> + default timeout is 30 seconds
>
> According to the SP805 TRM, the default interval is dependent on the
> rate of WDOGCLK, but would typically be a lot longer than that :/
>
> On a related note, anyone have any idea why we seem to have two subtly
> different SP805 bindings defined?
Interesting, I did not even know that until you pointed this out (and
it's funny that I found that I actually reviewed arm,sp805.txt
internally in Broadcom code review).
It looks like one was done by Bhupesh Sharma (sp805-wdt.txt) and the
other was done by Anup Patel (arm,sp805.txt). Both were merged at the
same time around March 20, 2016: 915c56bc01d6. I'd assume both were sent
out at around the same time.
It sounds like we should definitely remove one of them. Given that
sp805-wdt.txt appears to have more detailed descriptions on the use of
the clocks, should we remove arm,sp805.txt?
Thanks,
Ray
>
> Robin.
>
>> Examples:
>>
Hi Robin,
On 5/23/2018 4:48 AM, Robin Murphy wrote:
> On 23/05/18 08:52, Scott Branden wrote:
>>
>>
>> On 18-05-22 04:24 PM, Ray Jui wrote:
>>> Hi Guenter,
>>>
>>> On 5/22/2018 1:54 PM, Guenter Roeck wrote:
>>>> On Tue, May 22, 2018 at 11:47:18AM -0700, Ray Jui wrote:
>>>>> If the watchdog hardware is already enabled during the boot process,
>>>>> when the Linux watchdog driver loads, it should reset the watchdog and
>>>>> tell the watchdog framework. As a result, ping can be generated from
>>>>> the watchdog framework, until the userspace watchdog daemon takes over
>>>>> control
>>>>>
>>>>> Signed-off-by: Ray Jui <[email protected]>
>>>>> Reviewed-by: Vladimir Olovyannikov
>>>>> <[email protected]>
>>>>> Reviewed-by: Scott Branden <[email protected]>
>>>>> ---
>>>>> drivers/watchdog/sp805_wdt.c | 22 ++++++++++++++++++++++
>>>>> 1 file changed, 22 insertions(+)
>>>>>
>>>>> diff --git a/drivers/watchdog/sp805_wdt.c
>>>>> b/drivers/watchdog/sp805_wdt.c
>>>>> index 1484609..408ffbe 100644
>>>>> --- a/drivers/watchdog/sp805_wdt.c
>>>>> +++ b/drivers/watchdog/sp805_wdt.c
>>>>> @@ -42,6 +42,7 @@
>>>>> /* control register masks */
>>>>> #define INT_ENABLE (1 << 0)
>>>>> #define RESET_ENABLE (1 << 1)
>>>>> + #define ENABLE_MASK (INT_ENABLE | RESET_ENABLE)
>>>>> #define WDTINTCLR 0x00C
>>>>> #define WDTRIS 0x010
>>>>> #define WDTMIS 0x014
>>>>> @@ -74,6 +75,18 @@ module_param(nowayout, bool, 0);
>>>>> MODULE_PARM_DESC(nowayout,
>>>>> "Set to 1 to keep watchdog running after device release");
>>>>> +/* returns true if wdt is running; otherwise returns false */
>>>>> +static bool wdt_is_running(struct watchdog_device *wdd)
>>>>> +{
>>>>> + struct sp805_wdt *wdt = watchdog_get_drvdata(wdd);
>>>>> +
>>>>> + if ((readl_relaxed(wdt->base + WDTCONTROL) & ENABLE_MASK) ==
>>>>> + ENABLE_MASK)
>>>>> + return true;
>>>>> + else
>>>>> + return false;
>>>>
>>>> return !!(readl_relaxed(wdt->base + WDTCONTROL) & ENABLE_MASK));
>>>>
>>>
>>> Note ENABLE_MASK contains two bits (INT_ENABLE and RESET_ENABLE);
>>> therefore, a simple !!(expression) would not work? That is, the
>>> masked result needs to be compared against the mask again to ensure
>>> both bits are set, right?
>> Ray - your original code looks correct to me. Easier to read and less
>> prone to errors as shown in the attempted translation to a single
>> statement.
>
> if (<boolean condition>)
> return true;
> else
> return false;
>
> still looks really dumb, though, and IMO is actually harder to read than
> just "return <boolean condition>;" because it forces you to stop and
> double-check that the logic is, in fact, only doing the obvious thing.
If you can propose a way to modify my original code above to make it
more readable, I'm fine to make the change.
As I mentioned, I don't think the following change proposed by Guenter
will work due to the reason I pointed out:
return !!(readl_relaxed(wdt->base + WDTCONTROL) & ENABLE_MASK));
>
> Robin.
>
>
>
> p.s. No thanks for making me remember the mind-boggling horror of
> briefly maintaining part of this legacy codebase... :P
>
> $ grep -r '? true : false' --include=*.cpp . | wc -l
> 951
On 23/05/18 17:29, Ray Jui wrote:
> Hi Robin,
>
> On 5/23/2018 4:48 AM, Robin Murphy wrote:
>> On 23/05/18 08:52, Scott Branden wrote:
>>>
>>>
>>> On 18-05-22 04:24 PM, Ray Jui wrote:
>>>> Hi Guenter,
>>>>
>>>> On 5/22/2018 1:54 PM, Guenter Roeck wrote:
>>>>> On Tue, May 22, 2018 at 11:47:18AM -0700, Ray Jui wrote:
>>>>>> If the watchdog hardware is already enabled during the boot process,
>>>>>> when the Linux watchdog driver loads, it should reset the watchdog
>>>>>> and
>>>>>> tell the watchdog framework. As a result, ping can be generated from
>>>>>> the watchdog framework, until the userspace watchdog daemon takes
>>>>>> over
>>>>>> control
>>>>>>
>>>>>> Signed-off-by: Ray Jui <[email protected]>
>>>>>> Reviewed-by: Vladimir Olovyannikov
>>>>>> <[email protected]>
>>>>>> Reviewed-by: Scott Branden <[email protected]>
>>>>>> ---
>>>>>> drivers/watchdog/sp805_wdt.c | 22 ++++++++++++++++++++++
>>>>>> 1 file changed, 22 insertions(+)
>>>>>>
>>>>>> diff --git a/drivers/watchdog/sp805_wdt.c
>>>>>> b/drivers/watchdog/sp805_wdt.c
>>>>>> index 1484609..408ffbe 100644
>>>>>> --- a/drivers/watchdog/sp805_wdt.c
>>>>>> +++ b/drivers/watchdog/sp805_wdt.c
>>>>>> @@ -42,6 +42,7 @@
>>>>>> /* control register masks */
>>>>>> #define INT_ENABLE (1 << 0)
>>>>>> #define RESET_ENABLE (1 << 1)
>>>>>> + #define ENABLE_MASK (INT_ENABLE | RESET_ENABLE)
>>>>>> #define WDTINTCLR 0x00C
>>>>>> #define WDTRIS 0x010
>>>>>> #define WDTMIS 0x014
>>>>>> @@ -74,6 +75,18 @@ module_param(nowayout, bool, 0);
>>>>>> MODULE_PARM_DESC(nowayout,
>>>>>> "Set to 1 to keep watchdog running after device release");
>>>>>> +/* returns true if wdt is running; otherwise returns false */
>>>>>> +static bool wdt_is_running(struct watchdog_device *wdd)
>>>>>> +{
>>>>>> + struct sp805_wdt *wdt = watchdog_get_drvdata(wdd);
>>>>>> +
>>>>>> + if ((readl_relaxed(wdt->base + WDTCONTROL) & ENABLE_MASK) ==
>>>>>> + ENABLE_MASK)
>>>>>> + return true;
>>>>>> + else
>>>>>> + return false;
>>>>>
>>>>> return !!(readl_relaxed(wdt->base + WDTCONTROL) & ENABLE_MASK));
>>>>>
>>>>
>>>> Note ENABLE_MASK contains two bits (INT_ENABLE and RESET_ENABLE);
>>>> therefore, a simple !!(expression) would not work? That is, the
>>>> masked result needs to be compared against the mask again to ensure
>>>> both bits are set, right?
>>> Ray - your original code looks correct to me. Easier to read and
>>> less prone to errors as shown in the attempted translation to a
>>> single statement.
>>
>> if (<boolean condition>)
>> return true;
>> else
>> return false;
>>
>> still looks really dumb, though, and IMO is actually harder to read
>> than just "return <boolean condition>;" because it forces you to stop
>> and double-check that the logic is, in fact, only doing the obvious
>> thing.
>
> If you can propose a way to modify my original code above to make it
> more readable, I'm fine to make the change.
Well,
return readl_relaxed(wdt->base + WDTCONTROL) & ENABLE_MASK == ENABLE_MASK;
would probably be reasonable to anyone other than the 80-column zealots,
but removing the silly boolean-to-boolean translation idiom really only
emphasises the fact that it's fundamentally a big complex statement; for
maximum clarity I'd be inclined to separate the two logical operations
(read and comparison), e.g.:
u32 wdtcontrol = readl_relaxed(wdt->base + WDTCONTROL);
return wdtcontrol & ENABLE_MASK == ENABLE_MASK;
which is still -3 lines vs. the original.
> As I mentioned, I don't think the following change proposed by Guenter
> will work due to the reason I pointed out:
>
> return !!(readl_relaxed(wdt->base + WDTCONTROL) & ENABLE_MASK));
FWIW, getting the desired result should only need one logical not
swapping for a bitwise one there:
return !(~readl_relaxed(wdt->base + WDTCONTROL) & ENABLE_MASK);
but that's well into "too clever for its own good" territory ;)
Robin.
Raym
On 18-05-23 09:29 AM, Ray Jui wrote:
> Hi Robin,
>
> On 5/23/2018 4:48 AM, Robin Murphy wrote:
>> On 23/05/18 08:52, Scott Branden wrote:
>>>
>>>
>>> On 18-05-22 04:24 PM, Ray Jui wrote:
>>>> Hi Guenter,
>>>>
>>>> On 5/22/2018 1:54 PM, Guenter Roeck wrote:
>>>>> On Tue, May 22, 2018 at 11:47:18AM -0700, Ray Jui wrote:
>>>>>> If the watchdog hardware is already enabled during the boot process,
>>>>>> when the Linux watchdog driver loads, it should reset the
>>>>>> watchdog and
>>>>>> tell the watchdog framework. As a result, ping can be generated from
>>>>>> the watchdog framework, until the userspace watchdog daemon takes
>>>>>> over
>>>>>> control
>>>>>>
>>>>>> Signed-off-by: Ray Jui <[email protected]>
>>>>>> Reviewed-by: Vladimir Olovyannikov
>>>>>> <[email protected]>
>>>>>> Reviewed-by: Scott Branden <[email protected]>
>>>>>> ---
>>>>>> drivers/watchdog/sp805_wdt.c | 22 ++++++++++++++++++++++
>>>>>> 1 file changed, 22 insertions(+)
>>>>>>
>>>>>> diff --git a/drivers/watchdog/sp805_wdt.c
>>>>>> b/drivers/watchdog/sp805_wdt.c
>>>>>> index 1484609..408ffbe 100644
>>>>>> --- a/drivers/watchdog/sp805_wdt.c
>>>>>> +++ b/drivers/watchdog/sp805_wdt.c
>>>>>> @@ -42,6 +42,7 @@
>>>>>> /* control register masks */
>>>>>> #define INT_ENABLE (1 << 0)
>>>>>> #define RESET_ENABLE (1 << 1)
>>>>>> + #define ENABLE_MASK (INT_ENABLE | RESET_ENABLE)
>>>>>> #define WDTINTCLR 0x00C
>>>>>> #define WDTRIS 0x010
>>>>>> #define WDTMIS 0x014
>>>>>> @@ -74,6 +75,18 @@ module_param(nowayout, bool, 0);
>>>>>> MODULE_PARM_DESC(nowayout,
>>>>>> "Set to 1 to keep watchdog running after device release");
>>>>>> +/* returns true if wdt is running; otherwise returns false */
>>>>>> +static bool wdt_is_running(struct watchdog_device *wdd)
>>>>>> +{
>>>>>> + struct sp805_wdt *wdt = watchdog_get_drvdata(wdd);
>>>>>> +
>>>>>> + if ((readl_relaxed(wdt->base + WDTCONTROL) & ENABLE_MASK) ==
>>>>>> + ENABLE_MASK)
>>>>>> + return true;
>>>>>> + else
>>>>>> + return false;
>>>>>
>>>>> return !!(readl_relaxed(wdt->base + WDTCONTROL) & ENABLE_MASK));
>>>>>
>>>>
>>>> Note ENABLE_MASK contains two bits (INT_ENABLE and RESET_ENABLE);
>>>> therefore, a simple !!(expression) would not work? That is, the
>>>> masked result needs to be compared against the mask again to ensure
>>>> both bits are set, right?
>>> Ray - your original code looks correct to me. Easier to read and
>>> less prone to errors as shown in the attempted translation to a
>>> single statement.
>>
>> if (<boolean condition>)
>> return true;
>> else
>> return false;
>>
>> still looks really dumb, though, and IMO is actually harder to read
>> than just "return <boolean condition>;" because it forces you to stop
>> and double-check that the logic is, in fact, only doing the obvious
>> thing.
>
> If you can propose a way to modify my original code above to make it
> more readable, I'm fine to make the change.
>
> As I mentioned, I don't think the following change proposed by Guenter
> will work due to the reason I pointed out:
>
> return !!(readl_relaxed(wdt->base + WDTCONTROL) & ENABLE_MASK));
What they are looking for is:
return ((readl_relaxed(wdt->base + WDTCONTROL) & ENABLE_MASK) ==
ENABLE_MASK);
or maybe:
return !!((readl_relaxed(wdt->base + WDTCONTROL) & ENABLE_MASK) ==
ENABLE_MASK);
>
>>
>> Robin.
>>
>>
>>
>> p.s. No thanks for making me remember the mind-boggling horror of
>> briefly maintaining part of this legacy codebase... :P
>>
>> $ grep -r '? true : false' --include=*.cpp . | wc -l
>> 951
On Wed, May 23, 2018 at 12:48:10PM +0100, Robin Murphy wrote:
> On 23/05/18 08:52, Scott Branden wrote:
> >
> >
> >On 18-05-22 04:24 PM, Ray Jui wrote:
> >>Hi Guenter,
> >>
> >>On 5/22/2018 1:54 PM, Guenter Roeck wrote:
> >>>On Tue, May 22, 2018 at 11:47:18AM -0700, Ray Jui wrote:
> >>>>If the watchdog hardware is already enabled during the boot process,
> >>>>when the Linux watchdog driver loads, it should reset the watchdog and
> >>>>tell the watchdog framework. As a result, ping can be generated from
> >>>>the watchdog framework, until the userspace watchdog daemon takes over
> >>>>control
> >>>>
> >>>>Signed-off-by: Ray Jui <[email protected]>
> >>>>Reviewed-by: Vladimir Olovyannikov <[email protected]>
> >>>>Reviewed-by: Scott Branden <[email protected]>
> >>>>---
> >>>>? drivers/watchdog/sp805_wdt.c | 22 ++++++++++++++++++++++
> >>>>? 1 file changed, 22 insertions(+)
> >>>>
> >>>>diff --git a/drivers/watchdog/sp805_wdt.c
> >>>>b/drivers/watchdog/sp805_wdt.c
> >>>>index 1484609..408ffbe 100644
> >>>>--- a/drivers/watchdog/sp805_wdt.c
> >>>>+++ b/drivers/watchdog/sp805_wdt.c
> >>>>@@ -42,6 +42,7 @@
> >>>>????? /* control register masks */
> >>>>????? #define??? INT_ENABLE??? (1 << 0)
> >>>>????? #define??? RESET_ENABLE??? (1 << 1)
> >>>>+??? #define??? ENABLE_MASK??? (INT_ENABLE | RESET_ENABLE)
> >>>>? #define WDTINTCLR??????? 0x00C
> >>>>? #define WDTRIS??????????? 0x010
> >>>>? #define WDTMIS??????????? 0x014
> >>>>@@ -74,6 +75,18 @@ module_param(nowayout, bool, 0);
> >>>>? MODULE_PARM_DESC(nowayout,
> >>>>????????? "Set to 1 to keep watchdog running after device release");
> >>>>? +/* returns true if wdt is running; otherwise returns false */
> >>>>+static bool wdt_is_running(struct watchdog_device *wdd)
> >>>>+{
> >>>>+??? struct sp805_wdt *wdt = watchdog_get_drvdata(wdd);
> >>>>+
> >>>>+??? if ((readl_relaxed(wdt->base + WDTCONTROL) & ENABLE_MASK) ==
> >>>>+??????? ENABLE_MASK)
> >>>>+??????? return true;
> >>>>+??? else
> >>>>+??????? return false;
> >>>
> >>>????return !!(readl_relaxed(wdt->base + WDTCONTROL) & ENABLE_MASK));
> >>>
> >>
> >>Note ENABLE_MASK contains two bits (INT_ENABLE and RESET_ENABLE);
> >>therefore, a simple !!(expression) would not work? That is, the masked
> >>result needs to be compared against the mask again to ensure both bits
> >>are set, right?
> >Ray - your original code looks correct to me.? Easier to read and less
> >prone to errors as shown in the attempted translation to a single
> >statement.
>
> if (<boolean condition>)
> return true;
> else
> return false;
>
> still looks really dumb, though, and IMO is actually harder to read than
> just "return <boolean condition>;" because it forces you to stop and
> double-check that the logic is, in fact, only doing the obvious thing.
>
Yes, and I won't accept it, sorry.
Guenter
> Robin.
>
>
>
> p.s. No thanks for making me remember the mind-boggling horror of briefly
> maintaining part of this legacy codebase... :P
>
> $ grep -r '? true : false' --include=*.cpp . | wc -l
> 951
On Wed, May 23, 2018 at 06:15:14PM +0100, Robin Murphy wrote:
> On 23/05/18 17:29, Ray Jui wrote:
> >Hi Robin,
> >
> >On 5/23/2018 4:48 AM, Robin Murphy wrote:
> >>On 23/05/18 08:52, Scott Branden wrote:
> >>>
> >>>
> >>>On 18-05-22 04:24 PM, Ray Jui wrote:
> >>>>Hi Guenter,
> >>>>
> >>>>On 5/22/2018 1:54 PM, Guenter Roeck wrote:
> >>>>>On Tue, May 22, 2018 at 11:47:18AM -0700, Ray Jui wrote:
> >>>>>>If the watchdog hardware is already enabled during the boot process,
> >>>>>>when the Linux watchdog driver loads, it should reset the
> >>>>>>watchdog and
> >>>>>>tell the watchdog framework. As a result, ping can be generated from
> >>>>>>the watchdog framework, until the userspace watchdog daemon
> >>>>>>takes over
> >>>>>>control
> >>>>>>
> >>>>>>Signed-off-by: Ray Jui <[email protected]>
> >>>>>>Reviewed-by: Vladimir Olovyannikov
> >>>>>><[email protected]>
> >>>>>>Reviewed-by: Scott Branden <[email protected]>
> >>>>>>---
> >>>>>>? drivers/watchdog/sp805_wdt.c | 22 ++++++++++++++++++++++
> >>>>>>? 1 file changed, 22 insertions(+)
> >>>>>>
> >>>>>>diff --git a/drivers/watchdog/sp805_wdt.c
> >>>>>>b/drivers/watchdog/sp805_wdt.c
> >>>>>>index 1484609..408ffbe 100644
> >>>>>>--- a/drivers/watchdog/sp805_wdt.c
> >>>>>>+++ b/drivers/watchdog/sp805_wdt.c
> >>>>>>@@ -42,6 +42,7 @@
> >>>>>>????? /* control register masks */
> >>>>>>????? #define??? INT_ENABLE??? (1 << 0)
> >>>>>>????? #define??? RESET_ENABLE??? (1 << 1)
> >>>>>>+??? #define??? ENABLE_MASK??? (INT_ENABLE | RESET_ENABLE)
> >>>>>>? #define WDTINTCLR??????? 0x00C
> >>>>>>? #define WDTRIS??????????? 0x010
> >>>>>>? #define WDTMIS??????????? 0x014
> >>>>>>@@ -74,6 +75,18 @@ module_param(nowayout, bool, 0);
> >>>>>>? MODULE_PARM_DESC(nowayout,
> >>>>>>????????? "Set to 1 to keep watchdog running after device release");
> >>>>>>? +/* returns true if wdt is running; otherwise returns false */
> >>>>>>+static bool wdt_is_running(struct watchdog_device *wdd)
> >>>>>>+{
> >>>>>>+??? struct sp805_wdt *wdt = watchdog_get_drvdata(wdd);
> >>>>>>+
> >>>>>>+??? if ((readl_relaxed(wdt->base + WDTCONTROL) & ENABLE_MASK) ==
> >>>>>>+??????? ENABLE_MASK)
> >>>>>>+??????? return true;
> >>>>>>+??? else
> >>>>>>+??????? return false;
> >>>>>
> >>>>>????return !!(readl_relaxed(wdt->base + WDTCONTROL) & ENABLE_MASK));
> >>>>>
> >>>>
> >>>>Note ENABLE_MASK contains two bits (INT_ENABLE and RESET_ENABLE);
> >>>>therefore, a simple !!(expression) would not work? That is, the
> >>>>masked result needs to be compared against the mask again to ensure
> >>>>both bits are set, right?
> >>>Ray - your original code looks correct to me.? Easier to read and less
> >>>prone to errors as shown in the attempted translation to a single
> >>>statement.
> >>
> >>?????if (<boolean condition>)
> >>???????? return true;
> >>?????else
> >>???????? return false;
> >>
> >>still looks really dumb, though, and IMO is actually harder to read than
> >>just "return <boolean condition>;" because it forces you to stop and
> >>double-check that the logic is, in fact, only doing the obvious thing.
> >
> >If you can propose a way to modify my original code above to make it more
> >readable, I'm fine to make the change.
>
> Well,
>
> return readl_relaxed(wdt->base + WDTCONTROL) & ENABLE_MASK == ENABLE_MASK;
>
> would probably be reasonable to anyone other than the 80-column zealots, but
> removing the silly boolean-to-boolean translation idiom really only
> emphasises the fact that it's fundamentally a big complex statement; for
> maximum clarity I'd be inclined to separate the two logical operations (read
> and comparison), e.g.:
>
> u32 wdtcontrol = readl_relaxed(wdt->base + WDTCONTROL);
>
> return wdtcontrol & ENABLE_MASK == ENABLE_MASK;
== has higher precendence than bitwise &, so this will need ( ),
but otherwise I agree.
>
> which is still -3 lines vs. the original.
>
> >As I mentioned, I don't think the following change proposed by Guenter
> >will work due to the reason I pointed out:
> >
> >return !!(readl_relaxed(wdt->base + WDTCONTROL) & ENABLE_MASK));
>
> FWIW, getting the desired result should only need one logical not swapping
> for a bitwise one there:
>
> return !(~readl_relaxed(wdt->base + WDTCONTROL) & ENABLE_MASK);
>
> but that's well into "too clever for its own good" territory ;)
Yes, that would be confusing.
>
> Robin.
On Wed, May 23, 2018 at 11:57:25AM +0100, Robin Murphy wrote:
> On 22/05/18 19:47, Ray Jui wrote:
> >Update the SP805 binding document to add optional 'timeout-sec'
> >devicetree property
> >
> >Signed-off-by: Ray Jui <[email protected]>
> >Reviewed-by: Scott Branden <[email protected]>
> >---
> > Documentation/devicetree/bindings/watchdog/sp805-wdt.txt | 2 ++
> > 1 file changed, 2 insertions(+)
> >
> >diff --git a/Documentation/devicetree/bindings/watchdog/sp805-wdt.txt b/Documentation/devicetree/bindings/watchdog/sp805-wdt.txt
> >index edc4f0e..f898a86 100644
> >--- a/Documentation/devicetree/bindings/watchdog/sp805-wdt.txt
> >+++ b/Documentation/devicetree/bindings/watchdog/sp805-wdt.txt
> >@@ -19,6 +19,8 @@ Required properties:
> > Optional properties:
> > - interrupts : Should specify WDT interrupt number.
> >+- timeout-sec : Should specify default WDT timeout in seconds. If unset, the
> >+ default timeout is 30 seconds
>
> According to the SP805 TRM, the default interval is dependent on the rate of
> WDOGCLK, but would typically be a lot longer than that :/
>
Depends on the definition of "default". In the context of watchdog drivers,
it is (or should be) a driver default, not a chip default.
Guenter
> On a related note, anyone have any idea why we seem to have two subtly
> different SP805 bindings defined?
>
> Robin.
>
> > Examples:
> >
> --
> To unsubscribe from this list: send the line "unsubscribe linux-watchdog" in
> the body of a message to [email protected]
> More majordomo info at http://vger.kernel.org/majordomo-info.html
On Wed, May 23, 2018 at 09:25:49AM -0700, Ray Jui wrote:
>
>
> On 5/23/2018 3:57 AM, Robin Murphy wrote:
> > On 22/05/18 19:47, Ray Jui wrote:
> > > Update the SP805 binding document to add optional 'timeout-sec'
> > > devicetree property
> > >
> > > Signed-off-by: Ray Jui <[email protected]>
> > > Reviewed-by: Scott Branden <[email protected]>
> > > ---
> > > ? Documentation/devicetree/bindings/watchdog/sp805-wdt.txt | 2 ++
> > > ? 1 file changed, 2 insertions(+)
> > >
> > > diff --git
> > > a/Documentation/devicetree/bindings/watchdog/sp805-wdt.txt
> > > b/Documentation/devicetree/bindings/watchdog/sp805-wdt.txt
> > > index edc4f0e..f898a86 100644
> > > --- a/Documentation/devicetree/bindings/watchdog/sp805-wdt.txt
> > > +++ b/Documentation/devicetree/bindings/watchdog/sp805-wdt.txt
> > > @@ -19,6 +19,8 @@ Required properties:
> > > ? Optional properties:
> > > ? - interrupts : Should specify WDT interrupt number.
> > > +- timeout-sec : Should specify default WDT timeout in seconds. If
> > > unset, the
> > > +??????????????? default timeout is 30 seconds
> >
> > According to the SP805 TRM, the default interval is dependent on the
> > rate of WDOGCLK, but would typically be a lot longer than that :/
> >
> > On a related note, anyone have any idea why we seem to have two subtly
> > different SP805 bindings defined?
Sigh.
> Interesting, I did not even know that until you pointed this out (and it's
> funny that I found that I actually reviewed arm,sp805.txt internally in
> Broadcom code review).
>
> It looks like one was done by Bhupesh Sharma (sp805-wdt.txt) and the other
> was done by Anup Patel (arm,sp805.txt). Both were merged at the same time
> around March 20, 2016: 915c56bc01d6. I'd assume both were sent out at around
> the same time.
>
> It sounds like we should definitely remove one of them. Given that
> sp805-wdt.txt appears to have more detailed descriptions on the use of the
> clocks, should we remove arm,sp805.txt?
Take whichever text you like, but I prefer filenames using the
compatible string and the correct string is 'arm,sp805' because '-wdt'
is redundant. You can probably safely just update all the dts files with
'arm,sp805' and just remove 'arm,sp805-wdt' because it is not actually
used (as the ID registers are).
Rob
On 5/23/2018 11:59 AM, Rob Herring wrote:
> On Wed, May 23, 2018 at 09:25:49AM -0700, Ray Jui wrote:
>>
>>
>> On 5/23/2018 3:57 AM, Robin Murphy wrote:
>>> On 22/05/18 19:47, Ray Jui wrote:
>>>> Update the SP805 binding document to add optional 'timeout-sec'
>>>> devicetree property
>>>>
>>>> Signed-off-by: Ray Jui <[email protected]>
>>>> Reviewed-by: Scott Branden <[email protected]>
>>>> ---
>>>> Documentation/devicetree/bindings/watchdog/sp805-wdt.txt | 2 ++
>>>> 1 file changed, 2 insertions(+)
>>>>
>>>> diff --git
>>>> a/Documentation/devicetree/bindings/watchdog/sp805-wdt.txt
>>>> b/Documentation/devicetree/bindings/watchdog/sp805-wdt.txt
>>>> index edc4f0e..f898a86 100644
>>>> --- a/Documentation/devicetree/bindings/watchdog/sp805-wdt.txt
>>>> +++ b/Documentation/devicetree/bindings/watchdog/sp805-wdt.txt
>>>> @@ -19,6 +19,8 @@ Required properties:
>>>> Optional properties:
>>>> - interrupts : Should specify WDT interrupt number.
>>>> +- timeout-sec : Should specify default WDT timeout in seconds. If
>>>> unset, the
>>>> + default timeout is 30 seconds
>>>
>>> According to the SP805 TRM, the default interval is dependent on the
>>> rate of WDOGCLK, but would typically be a lot longer than that :/
>>>
>>> On a related note, anyone have any idea why we seem to have two subtly
>>> different SP805 bindings defined?
>
> Sigh.
>
>> Interesting, I did not even know that until you pointed this out (and it's
>> funny that I found that I actually reviewed arm,sp805.txt internally in
>> Broadcom code review).
>>
>> It looks like one was done by Bhupesh Sharma (sp805-wdt.txt) and the other
>> was done by Anup Patel (arm,sp805.txt). Both were merged at the same time
>> around March 20, 2016: 915c56bc01d6. I'd assume both were sent out at around
>> the same time.
>>
>> It sounds like we should definitely remove one of them. Given that
>> sp805-wdt.txt appears to have more detailed descriptions on the use of the
>> clocks, should we remove arm,sp805.txt?
>
> Take whichever text you like, but I prefer filenames using the
> compatible string and the correct string is 'arm,sp805' because '-wdt'
> is redundant. You can probably safely just update all the dts files with
> 'arm,sp805' and just remove 'arm,sp805-wdt' because it is not actually
> used (as the ID registers are).
Okay. I'll consolidate everything into arm,sp805.txt. Will also fix all
DTS files to use "arm,sp805". The fix for actual DTS files will be in a
different patch series.
>
> Rob
>
Hi Guenter/Robin,
On 5/23/2018 11:09 AM, Guenter Roeck wrote:
> On Wed, May 23, 2018 at 06:15:14PM +0100, Robin Murphy wrote:
>> On 23/05/18 17:29, Ray Jui wrote:
>>> Hi Robin,
>>>
>>> On 5/23/2018 4:48 AM, Robin Murphy wrote:
>>>> On 23/05/18 08:52, Scott Branden wrote:
>>>>>
>>>>>
>>>>> On 18-05-22 04:24 PM, Ray Jui wrote:
>>>>>> Hi Guenter,
>>>>>>
>>>>>> On 5/22/2018 1:54 PM, Guenter Roeck wrote:
>>>>>>> On Tue, May 22, 2018 at 11:47:18AM -0700, Ray Jui wrote:
>>>>>>>> If the watchdog hardware is already enabled during the boot process,
>>>>>>>> when the Linux watchdog driver loads, it should reset the
>>>>>>>> watchdog and
>>>>>>>> tell the watchdog framework. As a result, ping can be generated from
>>>>>>>> the watchdog framework, until the userspace watchdog daemon
>>>>>>>> takes over
>>>>>>>> control
>>>>>>>>
>>>>>>>> Signed-off-by: Ray Jui <[email protected]>
>>>>>>>> Reviewed-by: Vladimir Olovyannikov
>>>>>>>> <[email protected]>
>>>>>>>> Reviewed-by: Scott Branden <[email protected]>
>>>>>>>> ---
>>>>>>>> drivers/watchdog/sp805_wdt.c | 22 ++++++++++++++++++++++
>>>>>>>> 1 file changed, 22 insertions(+)
>>>>>>>>
>>>>>>>> diff --git a/drivers/watchdog/sp805_wdt.c
>>>>>>>> b/drivers/watchdog/sp805_wdt.c
>>>>>>>> index 1484609..408ffbe 100644
>>>>>>>> --- a/drivers/watchdog/sp805_wdt.c
>>>>>>>> +++ b/drivers/watchdog/sp805_wdt.c
>>>>>>>> @@ -42,6 +42,7 @@
>>>>>>>> /* control register masks */
>>>>>>>> #define INT_ENABLE (1 << 0)
>>>>>>>> #define RESET_ENABLE (1 << 1)
>>>>>>>> + #define ENABLE_MASK (INT_ENABLE | RESET_ENABLE)
>>>>>>>> #define WDTINTCLR 0x00C
>>>>>>>> #define WDTRIS 0x010
>>>>>>>> #define WDTMIS 0x014
>>>>>>>> @@ -74,6 +75,18 @@ module_param(nowayout, bool, 0);
>>>>>>>> MODULE_PARM_DESC(nowayout,
>>>>>>>> "Set to 1 to keep watchdog running after device release");
>>>>>>>> +/* returns true if wdt is running; otherwise returns false */
>>>>>>>> +static bool wdt_is_running(struct watchdog_device *wdd)
>>>>>>>> +{
>>>>>>>> + struct sp805_wdt *wdt = watchdog_get_drvdata(wdd);
>>>>>>>> +
>>>>>>>> + if ((readl_relaxed(wdt->base + WDTCONTROL) & ENABLE_MASK) ==
>>>>>>>> + ENABLE_MASK)
>>>>>>>> + return true;
>>>>>>>> + else
>>>>>>>> + return false;
>>>>>>>
>>>>>>> return !!(readl_relaxed(wdt->base + WDTCONTROL) & ENABLE_MASK));
>>>>>>>
>>>>>>
>>>>>> Note ENABLE_MASK contains two bits (INT_ENABLE and RESET_ENABLE);
>>>>>> therefore, a simple !!(expression) would not work? That is, the
>>>>>> masked result needs to be compared against the mask again to ensure
>>>>>> both bits are set, right?
>>>>> Ray - your original code looks correct to me. Easier to read and less
>>>>> prone to errors as shown in the attempted translation to a single
>>>>> statement.
>>>>
>>>> if (<boolean condition>)
>>>> return true;
>>>> else
>>>> return false;
>>>>
>>>> still looks really dumb, though, and IMO is actually harder to read than
>>>> just "return <boolean condition>;" because it forces you to stop and
>>>> double-check that the logic is, in fact, only doing the obvious thing.
>>>
>>> If you can propose a way to modify my original code above to make it more
>>> readable, I'm fine to make the change.
>>
>> Well,
>>
>> return readl_relaxed(wdt->base + WDTCONTROL) & ENABLE_MASK == ENABLE_MASK;
>>
>> would probably be reasonable to anyone other than the 80-column zealots, but
>> removing the silly boolean-to-boolean translation idiom really only
>> emphasises the fact that it's fundamentally a big complex statement; for
>> maximum clarity I'd be inclined to separate the two logical operations (read
>> and comparison), e.g.:
>>
>> u32 wdtcontrol = readl_relaxed(wdt->base + WDTCONTROL);
>>
>> return wdtcontrol & ENABLE_MASK == ENABLE_MASK;
>
> == has higher precendence than bitwise &, so this will need ( ),
> but otherwise I agree.
>
Sure. Let me change the code to the following:
u32 wdtcontrol = readl_relaxed(wdt->base + WDTCONTROL);
return (wdtcontrol & ENABLE_MASK) == ENABLE_MASK;
Thanks.
Ray
>>
>> which is still -3 lines vs. the original.
>>
>>> As I mentioned, I don't think the following change proposed by Guenter
>>> will work due to the reason I pointed out:
>>>
>>> return !!(readl_relaxed(wdt->base + WDTCONTROL) & ENABLE_MASK));
>>
>> FWIW, getting the desired result should only need one logical not swapping
>> for a bitwise one there:
>>
>> return !(~readl_relaxed(wdt->base + WDTCONTROL) & ENABLE_MASK);
>>
>> but that's well into "too clever for its own good" territory ;)
>
> Yes, that would be confusing.
>
>>
>> Robin.
On 23/05/18 19:10, Guenter Roeck wrote:
> On Wed, May 23, 2018 at 11:57:25AM +0100, Robin Murphy wrote:
>> On 22/05/18 19:47, Ray Jui wrote:
>>> Update the SP805 binding document to add optional 'timeout-sec'
>>> devicetree property
>>>
>>> Signed-off-by: Ray Jui <[email protected]>
>>> Reviewed-by: Scott Branden <[email protected]>
>>> ---
>>> Documentation/devicetree/bindings/watchdog/sp805-wdt.txt | 2 ++
>>> 1 file changed, 2 insertions(+)
>>>
>>> diff --git a/Documentation/devicetree/bindings/watchdog/sp805-wdt.txt b/Documentation/devicetree/bindings/watchdog/sp805-wdt.txt
>>> index edc4f0e..f898a86 100644
>>> --- a/Documentation/devicetree/bindings/watchdog/sp805-wdt.txt
>>> +++ b/Documentation/devicetree/bindings/watchdog/sp805-wdt.txt
>>> @@ -19,6 +19,8 @@ Required properties:
>>> Optional properties:
>>> - interrupts : Should specify WDT interrupt number.
>>> +- timeout-sec : Should specify default WDT timeout in seconds. If unset, the
>>> + default timeout is 30 seconds
>>
>> According to the SP805 TRM, the default interval is dependent on the rate of
>> WDOGCLK, but would typically be a lot longer than that :/
>>
> Depends on the definition of "default". In the context of watchdog drivers,
> it is (or should be) a driver default, not a chip default.
DT describes hardware, not driver behaviour.
I appreciate that where a timeout *is* specified, that is effectively a
hardware aspect even if it's something an OS consuming the binding still
has to voluntarily program into the device. The notion of "this is the
longest period of time for which you can reasonably expect to see no
activity under normal operation" is indeed a property of the platform as
a whole - a system with user-accessible PCIe slots may need to reflect
the worst case of one CPU waiting for an ATS invalidation timeout with
interrupts disabled, whereas a much shorter period might be appropriate
for the same SoC in some closed-down embedded device.
The absence of the property, though, doesn't convey anything other than
"I don't know" and/or "it doesn't really matter", and in that situation
the default is always going to be "whatever the OS thinks is
appropriate". The binding itself can't possibly know, whereas an OS
might be configured for some pseudo-real-time application which it knows
warrants a maximum of 100ms regardless of what the DT does or doesn't
say. In the case of SP805, if the OS doesn't reconfigure it at all,
there happens to be an actual hardware default of (2^32 / WDOGCLK), but
since that's already implicit in the compatible it doesn't really need
saying either.
Optional properties don't need to explicitly state what their absence
might infer, especially when it's not directly meaningful (just imagine
trying to do that for bindings/regulator/regulator.txt...), so I would
suggest following the 93% of existing bindings which simply don't try to
claim some default value for this property.
I also think the fact that, within the context of this patch series, the
Linux driver doesn't even do what the binding claims only goes to help
make my point ;)
Robin.
On 23/05/18 20:29, Ray Jui wrote:
>
>
> On 5/23/2018 11:59 AM, Rob Herring wrote:
>> On Wed, May 23, 2018 at 09:25:49AM -0700, Ray Jui wrote:
>>>
>>>
>>> On 5/23/2018 3:57 AM, Robin Murphy wrote:
>>>> On 22/05/18 19:47, Ray Jui wrote:
>>>>> Update the SP805 binding document to add optional 'timeout-sec'
>>>>> devicetree property
>>>>>
>>>>> Signed-off-by: Ray Jui <[email protected]>
>>>>> Reviewed-by: Scott Branden <[email protected]>
>>>>> ---
>>>>> Documentation/devicetree/bindings/watchdog/sp805-wdt.txt | 2 ++
>>>>> 1 file changed, 2 insertions(+)
>>>>>
>>>>> diff --git
>>>>> a/Documentation/devicetree/bindings/watchdog/sp805-wdt.txt
>>>>> b/Documentation/devicetree/bindings/watchdog/sp805-wdt.txt
>>>>> index edc4f0e..f898a86 100644
>>>>> --- a/Documentation/devicetree/bindings/watchdog/sp805-wdt.txt
>>>>> +++ b/Documentation/devicetree/bindings/watchdog/sp805-wdt.txt
>>>>> @@ -19,6 +19,8 @@ Required properties:
>>>>> Optional properties:
>>>>> - interrupts : Should specify WDT interrupt number.
>>>>> +- timeout-sec : Should specify default WDT timeout in seconds. If
>>>>> unset, the
>>>>> + default timeout is 30 seconds
>>>>
>>>> According to the SP805 TRM, the default interval is dependent on the
>>>> rate of WDOGCLK, but would typically be a lot longer than that :/
>>>>
>>>> On a related note, anyone have any idea why we seem to have two subtly
>>>> different SP805 bindings defined?
>>
>> Sigh.
>>
>>> Interesting, I did not even know that until you pointed this out (and
>>> it's
>>> funny that I found that I actually reviewed arm,sp805.txt internally in
>>> Broadcom code review).
>>>
>>> It looks like one was done by Bhupesh Sharma (sp805-wdt.txt) and the
>>> other
>>> was done by Anup Patel (arm,sp805.txt). Both were merged at the same
>>> time
>>> around March 20, 2016: 915c56bc01d6. I'd assume both were sent out at
>>> around
>>> the same time.
>>>
>>> It sounds like we should definitely remove one of them. Given that
>>> sp805-wdt.txt appears to have more detailed descriptions on the use
>>> of the
>>> clocks, should we remove arm,sp805.txt?
>>
>> Take whichever text you like, but I prefer filenames using the
>> compatible string and the correct string is 'arm,sp805' because '-wdt'
>> is redundant. You can probably safely just update all the dts files with
>> 'arm,sp805' and just remove 'arm,sp805-wdt' because it is not actually
>> used (as the ID registers are).
>
> Okay. I'll consolidate everything into arm,sp805.txt. Will also fix all
> DTS files to use "arm,sp805". The fix for actual DTS files will be in a
> different patch series.
Looking at the current in-tree DTs, for extra fun try to figure out
which binding each instance was following for the clocks. The most
common answer seems to be "neither"... :(
Robin.
On Thu, May 24, 2018 at 02:25:34PM +0100, Robin Murphy wrote:
> On 23/05/18 19:10, Guenter Roeck wrote:
> >On Wed, May 23, 2018 at 11:57:25AM +0100, Robin Murphy wrote:
> >>On 22/05/18 19:47, Ray Jui wrote:
> >>>Update the SP805 binding document to add optional 'timeout-sec'
> >>>devicetree property
> >>>
> >>>Signed-off-by: Ray Jui <[email protected]>
> >>>Reviewed-by: Scott Branden <[email protected]>
> >>>---
> >>> Documentation/devicetree/bindings/watchdog/sp805-wdt.txt | 2 ++
> >>> 1 file changed, 2 insertions(+)
> >>>
> >>>diff --git a/Documentation/devicetree/bindings/watchdog/sp805-wdt.txt b/Documentation/devicetree/bindings/watchdog/sp805-wdt.txt
> >>>index edc4f0e..f898a86 100644
> >>>--- a/Documentation/devicetree/bindings/watchdog/sp805-wdt.txt
> >>>+++ b/Documentation/devicetree/bindings/watchdog/sp805-wdt.txt
> >>>@@ -19,6 +19,8 @@ Required properties:
> >>> Optional properties:
> >>> - interrupts : Should specify WDT interrupt number.
> >>>+- timeout-sec : Should specify default WDT timeout in seconds. If unset, the
> >>>+ default timeout is 30 seconds
> >>
> >>According to the SP805 TRM, the default interval is dependent on the rate of
> >>WDOGCLK, but would typically be a lot longer than that :/
> >>
> >Depends on the definition of "default". In the context of watchdog drivers,
> >it is (or should be) a driver default, not a chip default.
>
> DT describes hardware, not driver behaviour.
>
In this case it describes expected system behavior. Most definitely
it does not describe some hardware default.
Please note that I do not engage in discussions I consider bike-shedding.
This is one of those. Dropping out.
Guenter