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mpc52xx/wdt: OF property to enable the WDT on boot

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Add the "fsl,wdt-on-boot" OF property as to reserve a GPT as WDT which may
be a requirement in safety-related (e.g. ISO/EN 61508) applications.

Signed-off-by: Albrecht Dreß <albrecht.dress@arcor.de>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
This commit is contained in:
Albrecht Dreß 2009-11-13 11:09:30 -07:00 committed by Grant Likely
parent 690b846aa1
commit 13b600b59d
1 changed files with 16 additions and 1 deletions
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17
Documentation/powerpc/dts-bindings/fsl/mpc5200.txt
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@ -103,7 +103,22 @@ 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
fsl,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.
The watchdog will respect the CONFIG_WATCHDOG_NOWAYOUT option.
An mpc5200-gpt can be used as a single line GPIO controller. To do so,
add the following properties to the gpt node: