Re: [PATCH v3 6/6] ACPI: import watchdog info of GTDT into platform device

Hi Will,

On 26 May 2015 at 08:28, Will Deacon [off-list ref] wrote:

On Mon, May 25, 2015 at 11:03:13AM +0100, fu.wei@linaro.org wrote:

quoted

From: Fu Wei <redacted>

Parse SBSA Generic Watchdog Structure in GTDT table of ACPI,
and create a platform device with that information.
This platform device can be used by the ARM SBSA Generic
Watchdog driver.

Tested-by: Suravee Suthikulpanit <Suravee.Suthikulpanit@amd.com>
Tested-by: Timur Tabi <redacted>
Signed-off-by: Fu Wei <redacted>
---
 arch/arm64/kernel/acpi.c | 145 +++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 145 insertions(+)

Why does this all need to be under arch/arm64? The GTDT really isn't
architecture-specific, so I'd *much* rather it was parsed in the driver code
itself, like we already do for the architected timer. The GIC is an
exception because it's in the MADT, which we need to parse in the arch code
to configure SMP properly.

I'm not really against refactoring the code. But the GTDT looks quite
specific to ARM..

---8<----
5.2.24 Generic Timer Description Table (GTDT)
This section describes the format of the Generic Timer Description
Table (GTDT), which provides
OSPM with information about a system’s Generic Timers configuration.
The Generic Timer (GT) is
a standard timer interface implemented on ARM processor-based systems.
The GT hardware
specification can be found at Links to ACPI-Related Documents
(http://uefi.org/acpi) under the
heading ARM Architecture. The GTDT provides OSPM with information
about a system's GT
interrupt configurations, for both per-processor timers, and platform
(memory-mapped) timers.
The GT specification defines the following per-processor timers:
• Secure privilege level 1 (EL1) timer,
• Non-Secure EL1 timer,
• Non-Secure privilege level 2 (EL2) timer,
• Virtual timer,
and the following Platform (memory-mapped) timers.
• GT Block
• Server Base System Architecture (SBSA) Generic Watchdog
---8<----

Thanks,
Ashwin.