[PATCH 1/2 v2] intel_pstate: skip this driver if Sun server has _PPC method

[Ethan Zhao <ethan.zhao@oracle.com>]

Oracle Sun X86 servers have dynamic power capping capability that works via
ACPI _PPC method etc, so skip loading this driver if Sun server has ACPI _PPC
enabled.

Signed-off-by: Ethan Zhao <ethan.zhao@oracle.com>

v2: only match ORACLE oem id.
---
 drivers/cpufreq/intel_pstate.c | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)

diff --git a/drivers/cpufreq/intel_pstate.c b/drivers/cpufreq/intel_pstate.c
index 27bb6d3..dacc15a 100644
--- a/drivers/cpufreq/intel_pstate.c
+++ b/drivers/cpufreq/intel_pstate.c
@@ -943,6 +943,21 @@ static bool intel_pstate_no_acpi_pss(void)
 	return true;
 }
 
+static bool intel_pstate_has_acpi_ppc(void)
+{
+	int i;
+
+	for_each_possible_cpu(i) {
+		struct acpi_processor *pr = per_cpu(processors, i);
+
+		if (!pr)
+			continue;
+		if (acpi_has_method(pr->handle, "_PPC"))
+			return true;
+	}
+	return false;
+}
+
 struct hw_vendor_info {
 	u16  valid;
 	char oem_id[ACPI_OEM_ID_SIZE];
@@ -952,6 +967,7 @@ struct hw_vendor_info {
 /* Hardware vendor-specific info that has its own power management modes */
 static struct hw_vendor_info vendor_info[] = {
 	{1, "HP    ", "ProLiant"},
+	{1, "ORACLE", ""},
 	{0, "", ""},
 };
 
@@ -970,11 +986,15 @@ static bool intel_pstate_platform_pwr_mgmt_exists(void)
 		    intel_pstate_no_acpi_pss())
 			return true;
 	}
+	if (!strncmp(hdr.oem_id, vendor_info[1].oem_id, ACPI_OEM_ID_SIZE) &&
+		intel_pstate_has_acpi_ppc())
+		return true;
 
 	return false;
 }
 #else /* CONFIG_ACPI not enabled */
 static inline bool intel_pstate_platform_pwr_mgmt_exists(void) { return false; }
+static inline bool intel_pstate_has_acpi_ppc(void) { return false; }
 #endif /* CONFIG_ACPI */
 
 static int __init intel_pstate_init(void)
-- 
1.8.3.1