PCI/ACPI: add a helper for retrieving _OSC Control DWORDs

During _OSC negotiation, when the 'Control' DWORD is needed from the
result buffer after running _OSC, a couple of places performed manual
pointer arithmetic to offset into the right spot in the raw buffer.
Add a acpi_osc_ctx_get_pci_control() helper to use the #define'd
DWORD offsets to fetch the DWORDs needed from @acpi_osc_context, and
replace the above instances of the open-coded arithmetic.

Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Suggested-by: Davidlohr Bueso <dave@stgolabs.net>
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: Davidlohr Bueso <dave@stgolabs.net>
Reviewed by: Adam Manzanares <a.manzanares@samsung.com>
Signed-off-by: Vishal Verma <vishal.l.verma@intel.com>
Link: https://lore.kernel.org/r/20220413073618.291335-2-vishal.l.verma@intel.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>

1 files changed, 1 insertions, 1 deletions

diff --git a/drivers/acpi/pci_root.c b/drivers/acpi/pci_root.c
index 6f9e75d14808..57be89cb3966 100644
--- a/drivers/acpi/pci_root.c
+++ b/drivers/acpi/pci_root.c
@@ -183,7 +183,7 @@ static acpi_status acpi_pci_run_osc(acpi_handle handle,
 
 	status = acpi_run_osc(handle, &context);
 	if (ACPI_SUCCESS(status)) {
-		*retval = *((u32 *)(context.ret.pointer + 8));
+		*retval = acpi_osc_ctx_get_pci_control(&context);
 		kfree(context.ret.pointer);
 	}
 	return status;