[PATCH v4 6/6] cpufreq: CPPC: Support for autonomous selection in cppc_cpufreq

Lifeng Zheng
2025-01-13T12:21:18Z

Add sysfs interfaces for CPPC autonomous selection in the cppc_cpufreq
driver.

Signed-off-by: Lifeng Zheng <zhenglifeng1@huawei.com>
---
.../ABI/testing/sysfs-devices-system-cpu | 54 +++++++++
drivers/cpufreq/cppc_cpufreq.c | 109 ++++++++++++++++++
2 files changed, 163 insertions(+)

diff --git a/Documentation/ABI/testing/sysfs-devices-system-cpu b/Documentation/ABI/testing/sysfs-devices-system-cpu
index 206079d3bd5b..3d87c3bb3fe2 100644
--- a/Documentation/ABI/testing/sysfs-devices-system-cpu
+++ b/Documentation/ABI/testing/sysfs-devices-system-cpu
@@ -268,6 +268,60 @@ Description: Discover CPUs in the same CPU frequency coordination domain
This file is only present if the acpi-cpufreq or the cppc-cpufreq
drivers are in use.

+What: /sys/devices/system/cpu/cpuX/cpufreq/auto_select
+Date: October 2024
+Contact: linux-pm@vger.kernel.org
+Description: Autonomous selection enable
+
+ Read/write interface to control autonomous selection enable
+ Read returns autonomous selection status:
+ 0: autonomous selection is disabled
+ 1: autonomous selection is enabled
+
+ Write 'y' or '1' or 'on' to enable autonomous selection.
+ Write 'n' or '0' or 'off' to disable autonomous selection.
+
+ This file only presents if the cppc-cpufreq driver is in use.
+
+What: /sys/devices/system/cpu/cpuX/cpufreq/auto_act_window
+Date: October 2024
+Contact: linux-pm@vger.kernel.org
+Description: Autonomous activity window
+
+ This file indicates a moving utilization sensitivity window to
+ the platform's autonomous selection policy.
+
+ Read/write an integer represents autonomous activity window (in
+ microseconds) from/to this file. The max value to write is
+ 1270000000 but the max significand is 127. This means that if 128
+ is written to this file, 127 will be stored. If the value is
+ greater than 130, only the first two digits will be saved as
+ significand.
+
+ Writing a zero value to this file enable the platform to
+ determine an appropriate Activity Window depending on the workload.
+
+ Writing to this file only has meaning when Autonomous Selection is
+ enabled.
+
+ This file only presents if the cppc-cpufreq driver is in use.
+
+What: /sys/devices/system/cpu/cpuX/cpufreq/energy_perf
+Date: October 2024
+Contact: linux-pm@vger.kernel.org
+Description: Energy performance preference
+
+ Read/write an 8-bit integer from/to this file. This file
+ represents a range of values from 0 (performance preference) to
+ 0xFF (energy efficiency preference) that influences the rate of
+ performance increase/decrease and the result of the hardware's
+ energy efficiency and performance optimization policies.
+
+ Writing to this file only has meaning when Autonomous Selection is
+ enabled.
+
+ This file only presents if the cppc-cpufreq driver is in use.
+

What: /sys/devices/system/cpu/cpu*/cache/index3/cache_disable_{0,1}
Date: August 2008
diff --git a/drivers/cpufreq/cppc_cpufreq.c b/drivers/cpufreq/cppc_cpufreq.c
index bd8f75accfa0..ea6c6a5bbd8c 100644
--- a/drivers/cpufreq/cppc_cpufreq.c
+++ b/drivers/cpufreq/cppc_cpufreq.c
@@ -814,10 +814,119 @@ static ssize_t show_freqdomain_cpus(struct cpufreq_policy *policy, char *buf)

return cpufreq_show_cpus(cpu_data->shared_cpu_map, buf);
}
+
+static ssize_t show_auto_select(struct cpufreq_policy *policy, char *buf)
+{
+ bool val;
+ int ret;
+
+ ret = cppc_get_auto_sel(policy->cpu, &val);
+
+ /* show "<unsupported>" when this register is not supported by cpc */
+ if (ret == -EOPNOTSUPP)
+ return sysfs_emit(buf, "%s\n", "<unsupported>");
+
+ if (ret)
+ return ret;
+
+ return sysfs_emit(buf, "%d\n", val);
+}
+
+static ssize_t store_auto_select(struct cpufreq_policy *policy,
+ const char *buf, size_t count)
+{
+ bool val;
+ int ret;
+
+ ret = kstrtobool(buf, &val);
+ if (ret)
+ return ret;
+
+ ret = cppc_set_auto_sel(policy->cpu, val);
+ if (ret)
+ return ret;
+
+ return count;
+}
+
+static ssize_t show_auto_act_window(struct cpufreq_policy *policy, char *buf)
+{
+ u64 val;
+ int ret;
+
+ ret = cppc_get_auto_act_window(policy->cpu, &val);
+
+ /* show "<unsupported>" when this register is not supported by cpc */
+ if (ret == -EOPNOTSUPP)
+ return sysfs_emit(buf, "%s\n", "<unsupported>");
+
+ if (ret)
+ return ret;
+
+ return sysfs_emit(buf, "%llu\n", val);
+}
+
+static ssize_t store_auto_act_window(struct cpufreq_policy *policy,
+ const char *buf, size_t count)
+{
+ u64 usec;
+ int ret;
+
+ ret = kstrtou64(buf, 0, &usec);
+ if (ret)
+ return ret;
+
+ ret = cppc_set_auto_act_window(policy->cpu, usec);
+ if (ret)
+ return ret;
+
+ return count;
+}
+
+static ssize_t show_energy_perf(struct cpufreq_policy *policy, char *buf)
+{
+ u64 val;
+ int ret;
+
+ ret = cppc_get_epp_perf(policy->cpu, &val);
+
+ /* show "<unsupported>" when this register is not supported by cpc */
+ if (ret == -EOPNOTSUPP)
+ return sysfs_emit(buf, "%s\n", "<unsupported>");
+
+ if (ret)
+ return ret;
+
+ return sysfs_emit(buf, "%llu\n", val);
+}
+
+static ssize_t store_energy_perf(struct cpufreq_policy *policy,
+ const char *buf, size_t count)
+{
+ u64 val;
+ int ret;
+
+ ret = kstrtou64(buf, 0, &val);
+ if (ret)
+ return ret;
+
+ ret = cppc_set_epp(policy->cpu, val);
+ if (ret)
+ return ret;
+
+ return count;
+}
+
cpufreq_freq_attr_ro(freqdomain_cpus);
+cpufreq_freq_attr_rw(auto_select);
+cpufreq_freq_attr_rw(auto_act_window);
+cpufreq_freq_attr_rw(energy_perf);

static struct freq_attr *cppc_cpufreq_attr[] = {
&freqdomain_cpus,
+ &auto_select,
+ &auto_act_window,
+ &energy_perf,
NULL,
};

--
2.33.0