linux-kernel - [PATCH v2 3/4] cppc_cpufreq: expose information on frequency domains

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Date:   Mon, 14 Dec 2020 12:38:22 +0000
From:   Ionela Voinescu <ionela.voinescu@....com>
To:     rjw@...ysocki.net, viresh.kumar@...aro.org, lenb@...nel.org
Cc:     yousaf.kaukab@...e.com, jeremy.linton@....com, lukasz.luba@....com,
        valentin.schneider@....com, linux-acpi@...r.kernel.org,
        linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org,
        ionela.voinescu@....com
Subject: [PATCH v2 3/4] cppc_cpufreq: expose information on frequency domains

Use the existing sysfs attribute "freqdomain_cpus" to expose
information to userspace about CPUs in the same frequency domain.

Signed-off-by: Ionela Voinescu <ionela.voinescu@....com>
Acked-by: Viresh Kumar <viresh.kumar@...aro.org>
Cc: Rafael J. Wysocki <rjw@...ysocki.net>
Cc: Viresh Kumar <viresh.kumar@...aro.org>
---
 Documentation/ABI/testing/sysfs-devices-system-cpu |  3 ++-
 drivers/cpufreq/cppc_cpufreq.c                     | 14 ++++++++++++++
 2 files changed, 16 insertions(+), 1 deletion(-)

diff --git a/Documentation/ABI/testing/sysfs-devices-system-cpu b/Documentation/ABI/testing/sysfs-devices-system-cpu
index 1a04ca8162ad..0eee30b27ab6 100644
--- a/Documentation/ABI/testing/sysfs-devices-system-cpu
+++ b/Documentation/ABI/testing/sysfs-devices-system-cpu
@@ -264,7 +264,8 @@ Description:	Discover CPUs in the same CPU frequency coordination domain
 		attribute is useful for user space DVFS controllers to get better
 		power/performance results for platforms using acpi-cpufreq.
 
-		This file is only present if the acpi-cpufreq driver is in use.
+		This file is only present if the acpi-cpufreq or the cppc-cpufreq
+		drivers are in use.
 
 
 What:		/sys/devices/system/cpu/cpu*/cache/index3/cache_disable_{0,1}
diff --git a/drivers/cpufreq/cppc_cpufreq.c b/drivers/cpufreq/cppc_cpufreq.c
index f15a44c8b6b7..40b58d2dbbc6 100644
--- a/drivers/cpufreq/cppc_cpufreq.c
+++ b/drivers/cpufreq/cppc_cpufreq.c
@@ -402,6 +402,19 @@ static int cppc_cpufreq_set_boost(struct cpufreq_policy *policy, int state)
 	return 0;
 }
 
+static ssize_t show_freqdomain_cpus(struct cpufreq_policy *policy, char *buf)
+{
+	unsigned int cpu = policy->cpu;
+
+	return cpufreq_show_cpus(all_cpu_data[cpu]->shared_cpu_map, buf);
+}
+cpufreq_freq_attr_ro(freqdomain_cpus);
+
+static struct freq_attr *cppc_cpufreq_attr[] = {
+	&freqdomain_cpus,
+	NULL,
+};
+
 static struct cpufreq_driver cppc_cpufreq_driver = {
 	.flags = CPUFREQ_CONST_LOOPS,
 	.verify = cppc_verify_policy,
@@ -410,6 +423,7 @@ static struct cpufreq_driver cppc_cpufreq_driver = {
 	.init = cppc_cpufreq_cpu_init,
 	.stop_cpu = cppc_cpufreq_stop_cpu,
 	.set_boost = cppc_cpufreq_set_boost,
+	.attr = cppc_cpufreq_attr,
 	.name = "cppc_cpufreq",
 };
 
-- 
2.29.2.dirty