mpc52xx/wdt: OF property to enable the WDT on boot
PATCH 1/3 mpc52xx/wdt: OF property to enable the WDT on boot
Add the "wdt,on-boot" OF property as to reserve a GPT as WDT which may be a requirement in safety-related (e.g. ISO 61508) applications.
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Documentation/powerpc/dts-bindings/fsl/mpc5200.txt | 15 ++++++++++++++- 1 files changed, 14 insertions(+), 1 deletions(-)
Documentation/powerpc/dts-bindings/fsl/mpc5200.txt +14 -1
@@ -103,7 +103,20 @@ fsl,mpc5200-gpt nodes --------------------- On the mpc5200 and 5200b, GPT0 has a watchdog timer function. If the board design supports the internal wdt, then the device node for GPT0 should -include the empty property 'fsl,has-wdt'. +include the empty property 'fsl,has-wdt'. Note that this does not activate +the watchdog. The timer will function as a GPT if the timer api is used, and +it will function as watchdog if the watchdog device is used. The watchdog +mode has priority over the gpt mode, i.e. if the watchdog is activated, any +gpt api call to this timer will fail with -EBUSY. + +If you add the property + wdt,on-boot = <n>; +GPT0 will be marked as in-use watchdog, i.e. blocking every gpt access to it. +If n>0, the watchdog is started with a timeout of n seconds. If n=0, the +configuration of the watchdog is not touched. This is useful in two cases: +- just mark GPT0 as watchdog, blocking gpt accesses, and configure it later; +- do not touch a configuration assigned by the boot loader which supervises + the boot process itself. An mpc5200-gpt can be used as a single line GPIO controller. To do so, add the following properties to the gpt node:
Quoted 22 lines · Albrecht Dreß
Add the "wdt,on-boot" OF property as to reserve a GPT as WDT which may be a requirement in safety-related (e.g. ISO 61508) applications.
Signed-off-by Albrecht Dreß <[email protected]>---
Documentation/powerpc/dts-bindings/fsl/mpc5200.txt | 15 ++++++++++++++-
1 files changed, 14 insertions(+), 1 deletions(-)Documentation/powerpc/dts-bindings/fsl/mpc5200.txt +0
-0@@ -103,7 +103,20 @@ fsl,mpc5200-gpt nodes---------------------
On the mpc5200 and 5200b, GPT0 has a watchdog timer function. If the board design supports the internal wdt, then the device node for GPT0 shouldDocumentation/powerpc/dts-bindings/fsl/mpc5200.txt +4
-1-include the empty property 'fsl,has-wdt'. +include the empty property 'fsl,has-wdt'. Note that this does not activate +the watchdog. The timer will function as a GPT if the timer api is used, and +it will function as watchdog if the watchdog device is used. The watchdog +mode has priority over the gpt mode, i.e. if the watchdog is activated, any
Documentation/powerpc/dts-bindings/fsl/mpc5200.txt fsl,mpc5200-gpt nodes · line 119
Quoted 10 lines
Documentation/powerpc/dts-bindings/fsl/mpc5200.txt +10
-0+gpt api call to this timer will fail with -EBUSY. + +If you add the property + wdt,on-boot = <n>; +GPT0 will be marked as in-use watchdog, i.e. blocking every gpt access to it. +If n>0, the watchdog is started with a timeout of n seconds. If n=0, the +configuration of the watchdog is not touched. This is useful in two cases: +- just mark GPT0 as watchdog, blocking gpt accesses, and configure it later; +- do not touch a configuration assigned by the boot loader which supervises + the boot process itself.
I'm not *totally* convinced on the usage model, but I just need some time to think about it. Give me a day or so and ping me again if you haven't heard from me. However, until a common WDT binding is defined, this property needs to be named something like "fsl,wdt-on-boot".
Cheers,
g.
Signature · 2 lines
Grant Likely, B.Sc., P.Eng. Secret Lab Technologies Ltd.