[PATCH v9 09/13] cpufreq: amd-pstate: add driver working mode switch support

Perry Yuan
2022-12-25T16:36:28Z

From: Perry Yuan <Perry.Yuan@amd.com>

While amd-pstate driver was loaded with specific driver mode, it will
need to check which mode is enabled for the pstate driver,add this sysfs
entry to show the current status

$ cat /sys/devices/system/cpu/amd-pstate/status
active

Meanwhile, user can switch the pstate driver mode with writing mode
string to sysfs entry as below.

Enable passive mode:
$ sudo bash -c "echo passive > /sys/devices/system/cpu/amd-pstate/status"

Enable active mode (EPP driver mode):
$ sudo bash -c "echo active > /sys/devices/system/cpu/amd-pstate/status"

Signed-off-by: Perry Yuan <Perry.Yuan@amd.com>
---
drivers/cpufreq/amd-pstate.c | 118 +++++++++++++++++++++++++++++++++++
1 file changed, 118 insertions(+)

diff --git a/drivers/cpufreq/amd-pstate.c b/drivers/cpufreq/amd-pstate.c
index e3676d1a85c7..8ceca4524fc1 100644
--- a/drivers/cpufreq/amd-pstate.c
+++ b/drivers/cpufreq/amd-pstate.c
@@ -63,6 +63,7 @@ static struct cpufreq_driver *default_pstate_driver;
static struct cpufreq_driver amd_pstate_driver;
static struct cpufreq_driver amd_pstate_epp_driver;
static int cppc_state = AMD_PSTATE_DISABLE;
+struct kobject *amd_pstate_kobj;

static inline int get_mode_idx_from_str(const char *str, size_t size)
{
@@ -632,6 +633,8 @@ static int amd_pstate_cpu_init(struct cpufreq_policy *policy)
policy->driver_data = cpudata;

amd_pstate_boost_init(cpudata);
+ if (!default_pstate_driver->adjust_perf)
+ default_pstate_driver->adjust_perf = amd_pstate_adjust_perf;

return 0;

@@ -772,12 +775,99 @@ static ssize_t show_energy_performance_preference(
return sysfs_emit(buf, "%s\n", energy_perf_strings[preference]);
}

+static ssize_t amd_pstate_show_status(char *buf)
+{
+ if (!default_pstate_driver)
+ return sysfs_emit(buf, "off\n");
+
+ return sysfs_emit(buf, "%s\n", amd_pstate_mode_string[cppc_state]);
+}
+
+static void amd_pstate_driver_cleanup(void)
+{
+ default_pstate_driver = NULL;
+}
+
+static int amd_pstate_update_status(const char *buf, size_t size)
+{
+ int ret;
+ int mode_idx;
+
+ if (size > 7 || size < 3)
+ return -EINVAL;
+ mode_idx = get_mode_idx_from_str(buf, size);
+
+ switch(mode_idx) {
+ case AMD_PSTATE_DISABLE:
+ if (!default_pstate_driver)
+ return -EINVAL;
+ if (cppc_state == AMD_PSTATE_ACTIVE)
+ return -EBUSY;
+ ret = cpufreq_unregister_driver(default_pstate_driver);
+ amd_pstate_driver_cleanup();
+ break;
+ case AMD_PSTATE_PASSIVE:
+ if (default_pstate_driver) {
+ if (default_pstate_driver == &amd_pstate_driver)
+ return 0;
+ cpufreq_unregister_driver(default_pstate_driver);
+ cppc_state = AMD_PSTATE_PASSIVE;
+ default_pstate_driver = &amd_pstate_driver;
+ }
+
+ ret = cpufreq_register_driver(default_pstate_driver);
+ break;
+ case AMD_PSTATE_ACTIVE:
+ if (default_pstate_driver) {
+ if (default_pstate_driver == &amd_pstate_epp_driver)
+ return 0;
+ cpufreq_unregister_driver(default_pstate_driver);
+ default_pstate_driver = &amd_pstate_epp_driver;
+ cppc_state = AMD_PSTATE_ACTIVE;
+ }
+
+ ret = cpufreq_register_driver(default_pstate_driver);
+ break;
+ default:
+ break;
+ ret = -EINVAL;
+ }
+
+ return ret;
+}
+
+static ssize_t show_status(struct kobject *kobj,
+ struct kobj_attribute *attr, char *buf)
+{
+ ssize_t ret;
+
+ mutex_lock(&amd_pstate_driver_lock);
+ ret = amd_pstate_show_status(buf);
+ mutex_unlock(&amd_pstate_driver_lock);
+
+ return ret;
+}
+
+static ssize_t store_status(struct kobject *a, struct kobj_attribute *b,
+ const char *buf, size_t count)
+{
+ char *p = memchr(buf, '\n', count);
+ int ret;
+
+ mutex_lock(&amd_pstate_driver_lock);
+ ret = amd_pstate_update_status(buf, p ? p - buf : count);
+ mutex_unlock(&amd_pstate_driver_lock);
+
+ return ret < 0 ? ret : count;
+}
+
cpufreq_freq_attr_ro(amd_pstate_max_freq);
cpufreq_freq_attr_ro(amd_pstate_lowest_nonlinear_freq);

cpufreq_freq_attr_ro(amd_pstate_highest_perf);
cpufreq_freq_attr_rw(energy_performance_preference);
cpufreq_freq_attr_ro(energy_performance_available_preferences);
+define_one_global_rw(status);

static struct freq_attr *amd_pstate_attr[] = {
&amd_pstate_max_freq,
@@ -795,6 +885,15 @@ static struct freq_attr *amd_pstate_epp_attr[] = {
NULL,
};

+static struct attribute *pstate_global_attributes[] = {
+ &status.attr,
+ NULL
+};
+
+static const struct attribute_group amd_pstate_global_attr_group = {
+ .attrs = pstate_global_attributes,
+};
+
static int amd_pstate_epp_cpu_init(struct cpufreq_policy *policy)
{
int min_freq, max_freq, nominal_freq, lowest_nonlinear_freq, ret;
@@ -1154,6 +1253,25 @@ static int __init amd_pstate_init(void)
if (ret)
pr_err("failed to register with return %d\n", ret);

+ amd_pstate_kobj = kobject_create_and_add("amd-pstate", &cpu_subsys.dev_root->kobj);
+ if (!amd_pstate_kobj) {
+ ret = -EINVAL;
+ pr_err("global sysfs registration failed.\n");
+ goto kobject_free;
+ }
+
+ ret = sysfs_create_group(amd_pstate_kobj, &amd_pstate_global_attr_group);
+ if (ret) {
+ pr_err("sysfs attribute export failed with error %d.\n", ret);
+ goto global_attr_free;
+ }
+
+ return ret;
+
+global_attr_free:
+ kobject_put(amd_pstate_kobj);
+kobject_free:
+ cpufreq_unregister_driver(default_pstate_driver);
return ret;
}
device_initcall(amd_pstate_init);
--
2.34.1