* Qualcomm MSM Watchdog

Watchdog timer is configured with a bark and a bite time.
If the watchdog is not "pet" at regular intervals, the system
is assumed to have become non responsive and needs to be reset.
A warning in the form of a bark timeout leads to a bark interrupt
and a kernel panic. If the watchdog timer is still not reset,
a bite timeout occurs, which is an interrupt in the secure mode,
which leads to a reset of the SOC via the secure watchdog. The
driver needs the petting time, and the bark timeout to be programmed
into the watchdog, as well as the bark and bite irqs.

The device tree parameters for the watchdog are:

Required properties:

- compatible : "qcom,msm-watchdog"
- reg : offset and length of the register set for the watchdog block.
- reg-names : names corresponding to each reg property value.
        "wdt-base" - physical base address of watchdog timer registers
        "wdt-absent-base" - physical base address of watchdog absent register
- interrupts : should contain bark and bite irq numbers
- qcom,pet-time : Non zero time interval at which watchdog should be pet in ms.
- qcom,bark-time : Non zero timeout value for a watchdog bark in ms.
- qcom,userspace-watchdog :
        (boolean) Allow enabling the userspace-watchdog feature. This feature
        requires userspace to pet the watchdog every qcom,pet-time interval
        in addition to the existing kernel-level checks.
        This feature is supported through device sysfs files.

Optional properties:

- qcom,ipi-ping : (boolean) send keep alive ping to other cpus if present
- qcom,wakeup-enable : (boolean) enable non secure watchdog to freeze / unfreeze
                        automatically across suspend / resume path.
- qcom,scandump-sizes : an array of 32-bit values that contains the size of the
                        scandump memory region for each CPU, such that the nth
                        32 bit value maps to the scandump size for CPU n.

Example:

        qcom,wdt@f9017000 {
                compatible = "qcom,msm-watchdog";
                reg = <0xf9017000 0x1000>;
                reg-names = "wdt-base";
                interrupts = <0 3 0>, <0 4 0>;
                qcom,bark-time = <11000>;
                qcom,pet-time = <10000>;
                qcom,ipi-ping;
                qcom,wakeup-enable;
                qcom,scandump-size = <0x10100 0x10100 0x10100 0x10100>;
        };