[PATCH v10 04/12] cpufreq: amd-pstate: optimize driver working mode selection in amd_pstate_param()

Perry Yuan
2023-01-06T06:15:31Z

From: Wyes Karny <wyes.karny@amd.com>

The amd-pstate driver may support multiple working modes.
Introduce a variable to keep track of which mode is currently enabled.
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 registration.

Reviewed-by: Mario Limonciello <mario.limonciello@amd.com>
Signed-off-by: Perry Yuan <perry.yuan@amd.com>
Signed-off-by: Wyes Karny <wyes.karny@amd.com>
---
drivers/cpufreq/amd-pstate.c | 39 +++++++++++++++++++++++++++---------
include/linux/amd-pstate.h | 17 ++++++++++++++++
2 files changed, 46 insertions(+), 10 deletions(-)

diff --git a/drivers/cpufreq/amd-pstate.c b/drivers/cpufreq/amd-pstate.c
index 204e39006dda..1a8b31277620 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)
{
@@ -625,10 +636,10 @@ static int __init amd_pstate_init(void)
/*
* by default the pstate driver is disabled to load
* enable the amd_pstate passive mode driver explicitly
- * with amd_pstate=passive in kernel command line
+ * with amd_pstate=passive or other modes in kernel command line
*/
- if (!cppc_load) {
- pr_debug("driver load is disabled, boot with amd_pstate=passive to enable this\n");
+ if (cppc_state == AMD_PSTATE_DISABLE) {
+ pr_debug("driver load is disabled, boot with specific mode to enable this\n");
return -ENODEV;
}

@@ -670,16 +681,24 @@ 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..dae2ce0f6735 100644
--- a/include/linux/amd-pstate.h
+++ b/include/linux/amd-pstate.h
@@ -74,4 +74,21 @@ struct amd_cpudata {
bool boost_supported;
};

+/*
+ * enum amd_pstate_mode - driver working mode of amd pstate
+ */
+enum amd_pstate_mode {
+ AMD_PSTATE_DISABLE = 0,
+ AMD_PSTATE_PASSIVE,
+ AMD_PSTATE_ACTIVE,
+ AMD_PSTATE_MAX,
+};
+
+static const char * const amd_pstate_mode_string[] = {
+ [AMD_PSTATE_DISABLE] = "disable",
+ [AMD_PSTATE_PASSIVE] = "passive",
+ [AMD_PSTATE_ACTIVE] = "active",
+ NULL,
+};
+
#endif /* _LINUX_AMD_PSTATE_H */
--
2.34.1