[PATCH v8 05/13] cpufreq: amd-pstate: optimize driver working mode selection in amd_pstate_param()

[Perry Yuan]

There are some other amd pstate driver working mode to be supported.
Here we use cppc_state var to indicate which mode is enabled.
This change will help to simplify the the amd_pstate_param() to choose
which mode used for the following driver registeration.

Signed-off-by: Perry Yuan <perry.yuan@xxxxxxx>
Signed-off-by: Wyes Karny <wyes.karny@xxxxxxx>
---
 drivers/cpufreq/amd-pstate.c | 35 +++++++++++++++++++++++++++--------
 include/linux/amd-pstate.h   | 29 +++++++++++++++++++++++++++++
 2 files changed, 56 insertions(+), 8 deletions(-)

diff --git a/drivers/cpufreq/amd-pstate.c b/drivers/cpufreq/amd-pstate.c
index c17bd845f5fc..861a905f9324 100644
--- a/drivers/cpufreq/amd-pstate.c
+++ b/drivers/cpufreq/amd-pstate.c
@@ -60,7 +60,18 @@
  * module parameter to be able to enable it manually for debugging.
  */
 static struct cpufreq_driver amd_pstate_driver;
-static int cppc_load __initdata;
+static int cppc_state = AMD_PSTATE_DISABLE;
+
+static inline int get_mode_idx_from_str(const char *str, size_t size)
+{
+	int i;
+
+	for (i=0; i < AMD_PSTATE_MAX; i++) {
+		if (!strncmp(str, amd_pstate_mode_string[i], size))
+			return i;
+	}
+	return -EINVAL;
+}
 
 static inline int pstate_enable(bool enable)
 {
@@ -628,7 +639,7 @@ static int __init amd_pstate_init(void)
 	 * enable the amd_pstate passive mode driver explicitly
 	 * with amd_pstate=passive in kernel command line
 	 */
-	if (!cppc_load) {
+	if (cppc_state == AMD_PSTATE_DISABLE) {
 		pr_debug("driver load is disabled, boot with amd_pstate=passive to enable this\n");
 		return -ENODEV;
 	}
@@ -671,16 +682,24 @@ device_initcall(amd_pstate_init);
 
 static int __init amd_pstate_param(char *str)
 {
+	size_t size;
+	int mode_idx;
+
 	if (!str)
 		return -EINVAL;
 
-	if (!strcmp(str, "disable")) {
-		cppc_load = 0;
-		pr_info("driver is explicitly disabled\n");
-	} else if (!strcmp(str, "passive"))
-		cppc_load = 1;
+	size = strlen(str);
+	mode_idx = get_mode_idx_from_str(str, size);
 
-	return 0;
+	if (mode_idx >= AMD_PSTATE_DISABLE && mode_idx < AMD_PSTATE_MAX) {
+		cppc_state = mode_idx;
+		if (cppc_state == AMD_PSTATE_DISABLE)
+			pr_info("driver is explicitly disabled\n");
+
+		return 0;
+	}
+
+	return -EINVAL;
 }
 early_param("amd_pstate", amd_pstate_param);
 
diff --git a/include/linux/amd-pstate.h b/include/linux/amd-pstate.h
index 1c4b8659f171..922d05a13902 100644
--- a/include/linux/amd-pstate.h
+++ b/include/linux/amd-pstate.h
@@ -74,4 +74,33 @@ struct amd_cpudata {
 	bool	boost_supported;
 };
 
+/**
+ * enum amd_pstate_mode - driver working mode of amd pstate
+ */
+
+enum amd_pstate_mode {
+	/** @AMD_PSTATE_DISABLE: Driver mode is disabled */
+	AMD_PSTATE_DISABLE = 0,
+
+	/** @AMD_PSTATE_PASSIVE: Drier mode is passive mode */
+	AMD_PSTATE_PASSIVE = 1,
+
+	/** @AMD_PSTATE_ACTIVE: Driver mode is active mode */
+	AMD_PSTATE_ACTIVE = 2,
+
+	/** @AMD_PSTATE_GUIDE: Driver mode is guided mode */
+	AMD_PSTATE_GUIDE = 3,
+
+	/** @AMD_PSTATE_MAX */
+	AMD_PSTATE_MAX = 4,
+};
+
+static const char * const amd_pstate_mode_string[] = {
+	[AMD_PSTATE_DISABLE]     = "disable",
+	[AMD_PSTATE_PASSIVE]     = "passive",
+	[AMD_PSTATE_ACTIVE]      = "active",
+	[AMD_PSTATE_GUIDE]      = "guide",
+	NULL,
+};
+
 #endif /* _LINUX_AMD_PSTATE_H */
-- 
2.34.1