[PATCH v2] cpufreq: intel_pstate: skip the driver if ACPI has power mgmt option

[Adrian Huang <adrian.huang@hp.com>]

This patch minimizes indentation levels and re-defines some local variables.

Signed-off-by: Adrian Huang <adrian.huang@hp.com>
---
Changes since v1:
 * Minimize indentation levels (Commented by Rafael)
 * Re-define some local variables (Commented by Rafael)
 * Return -ENODEV if platform FW has power management modes (Commented by Dirk)

 drivers/cpufreq/intel_pstate.c | 70 ++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 70 insertions(+)

diff --git a/drivers/cpufreq/intel_pstate.c b/drivers/cpufreq/intel_pstate.c
index eb3fdc7..8770d67 100644
--- a/drivers/cpufreq/intel_pstate.c
+++ b/drivers/cpufreq/intel_pstate.c
@@ -26,6 +26,8 @@
 #include <linux/fs.h>
 #include <linux/debugfs.h>
 #include <trace/events/power.h>
+#include <linux/acpi.h>
+#include <acpi/processor.h>
 
 #include <asm/div64.h>
 #include <asm/msr.h>
@@ -129,6 +131,18 @@ static struct perf_limits limits = {
 	.max_sysfs_pct = 100,
 };
 
+struct hw_vendor_info {
+	u16  valid;
+	char oem_id[ACPI_OEM_ID_SIZE];
+	char oem_table_id[ACPI_OEM_TABLE_ID_SIZE];
+};
+
+/* Hardware vendor-specific info that has its own power management modes */
+static struct hw_vendor_info vendor_info[] = {
+	{1, "HP    ", "ProLiant"},
+	{0, "", ""},
+};
+
 static inline void pid_reset(struct _pid *pid, int setpoint, int busy,
 			int deadband, int integral) {
 	pid->setpoint = setpoint;
@@ -698,6 +712,55 @@ static int intel_pstate_msrs_not_valid(void)
 
 	return 0;
 }
+
+static bool intel_pstate_no_acpi_pss(void)
+{
+	int i;
+
+	for_each_possible_cpu(i) {
+		acpi_status status = AE_OK;
+		struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
+		struct acpi_processor *pr = per_cpu(processors, i);
+		union acpi_object *pss = NULL;
+
+		if (!pr)
+			continue;
+
+		status = acpi_evaluate_object(pr->handle, "_PSS",
+					      NULL, &buffer);
+		if (ACPI_FAILURE(status))
+			continue;
+
+		pss = buffer.pointer;
+		if (pss && (pss->type == ACPI_TYPE_PACKAGE)) {
+			kfree(buffer.pointer);
+			return false;
+		}
+
+		kfree(buffer.pointer);
+	}
+
+	return true;
+}
+
+static bool intel_pstate_platform_pwr_mgmt_exists(void)
+{
+	struct acpi_table_header hdr;
+	struct hw_vendor_info *v_info;
+
+	if (ACPI_FAILURE(acpi_get_table_header(ACPI_SIG_FADT, 0, &hdr)))
+		return false;
+
+	for (v_info = vendor_info; v_info->valid; v_info++) {
+		if (!strncmp(hdr.oem_id, v_info->oem_id, ACPI_OEM_ID_SIZE)
+		    && !strncmp(hdr.oem_table_id, v_info->oem_table_id, ACPI_OEM_TABLE_ID_SIZE)
+		    && intel_pstate_no_acpi_pss())
+			return true;
+	}
+
+	return false;
+}
+
 static int __init intel_pstate_init(void)
 {
 	int cpu, rc = 0;
@@ -706,6 +769,13 @@ static int __init intel_pstate_init(void)
 	if (no_load)
 		return -ENODEV;
 
+	/*
+	 * The Intel pstate driver will be ignored if the platform
+	 * firmware has its own power management modes.
+	 */
+	if (!acpi_disabled && intel_pstate_platform_pwr_mgmt_exists())
+		return -ENODEV;
+
 	id = x86_match_cpu(intel_pstate_cpu_ids);
 	if (!id)
 		return -ENODEV;
-- 
1.8.1.2