[PATCH v3] ARM64: kernel: implement ACPI parking protocol

Hi Lorenzo,

On Tue, Jan 26, 2016 at 3:10 AM, Lorenzo Pieralisi
[off-list ref] wrote:

The SBBR and ACPI specifications allow ACPI based systems that do not
implement PSCI (eg systems with no EL3) to boot through the ACPI parking
protocol specification[1].

This patch implements the ACPI parking protocol CPU operations, and adds
code that eases parsing the parking protocol data structures to the
ARM64 SMP initializion carried out at the same time as cpus enumeration.

To wake-up the CPUs from the parked state, this patch implements a
wakeup IPI for ARM64 (ie arch_send_wakeup_ipi_mask()) that mirrors the
ARM one, so that a specific IPI is sent for wake-up purpose in order
to distinguish it from other IPI sources.

Given the current ACPI MADT parsing API, the patch implements a glue
layer that helps passing MADT GICC data structure from SMP initialization
code to the parking protocol implementation somewhat overriding the CPU
operations interfaces. This to avoid creating a completely trasparent
DT/ACPI CPU operations layer that would require creating opaque
structure handling for CPUs data (DT represents CPU through DT nodes, ACPI
through static MADT table entries), which seems overkill given that ACPI
on ARM64 mandates only two booting protocols (PSCI and parking protocol),
so there is no need for further protocol additions.

Based on the original work by Mark Salter [off-list ref]

[1] https://acpica.org/sites/acpica/files/MP%20Startup%20for%20ARM%20platforms.docx

Signed-off-by: Lorenzo Pieralisi <redacted>
Cc: Will Deacon <redacted>
Cc: Hanjun Guo <redacted>
Cc: Loc Ho <redacted>
Cc: Sudeep Holla <redacted>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mark Salter <redacted>
Cc: Al Stone <redacted>

I had tested this with X-Gene Mustang board. It applies cleanly
against 4.5.0-rc1 and detected all CPU's. For those of you want to try
this, you need an FW update if you are using APM Tianocore. Otherwise,
it will stuck in very early booting stage.

Thanks,
Loc