linux-kernel - [PATCH v5 7/9] cpufreq: amd_pstate: add driver working mode status sysfs entry

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Date:   Tue, 29 Nov 2022 01:03:12 +0800
From:   Perry Yuan <perry.yuan@....com>
To:     <rafael.j.wysocki@...el.com>, <Mario.Limonciello@....com>,
        <ray.huang@....com>, <viresh.kumar@...aro.org>
CC:     <Deepak.Sharma@....com>, <Nathan.Fontenot@....com>,
        <Alexander.Deucher@....com>, <Shimmer.Huang@....com>,
        <Xiaojian.Du@....com>, <Li.Meng@....com>, <wyes.karny@....com>,
        <linux-pm@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: [PATCH v5 7/9] cpufreq: amd_pstate: add driver working mode status sysfs entry

From: Perry Yuan <Perry.Yuan@....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

Signed-off-by: Perry Yuan <Perry.Yuan@....com>
---
 drivers/cpufreq/amd-pstate.c | 44 ++++++++++++++++++++++++++++++++++++
 1 file changed, 44 insertions(+)

diff --git a/drivers/cpufreq/amd-pstate.c b/drivers/cpufreq/amd-pstate.c
index 3335e7aa76f1..07c26178853d 100644
--- a/drivers/cpufreq/amd-pstate.c
+++ b/drivers/cpufreq/amd-pstate.c
@@ -65,6 +65,8 @@ static int cppc_load __initdata;
 static int epp_off __initdata;
 
 static struct cpufreq_driver *default_pstate_driver;
+static struct cpufreq_driver amd_pstate_epp_driver;
+static struct cpufreq_driver amd_pstate_driver;
 static struct amd_cpudata **all_cpu_data;
 
 static struct amd_pstate_params global_params;
@@ -807,6 +809,46 @@ static ssize_t store_boost(struct kobject *a,
 	return count;
 }
 
+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", default_pstate_driver == &amd_pstate_epp_driver ?
+					"active" : "passive");
+}
+
+static int amd_pstate_update_status(const char *buf, size_t size)
+{
+	/* FIXME! */
+	return -EOPNOTSUPP;
+}
+
+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);
 
@@ -814,6 +856,7 @@ 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(boost);
+define_one_global_rw(status);
 
 static struct freq_attr *amd_pstate_attr[] = {
 	&amd_pstate_max_freq,
@@ -833,6 +876,7 @@ static struct freq_attr *amd_pstate_epp_attr[] = {
 
 static struct attribute *pstate_global_attributes[] = {
 	&boost.attr,
+	&status.attr,
 	NULL
 };
 
-- 
2.34.1