This patch create debugfs root directory and child directory according to
the number of CPUs for CPUFreq as below debugfs directory path:
- /sys/kernel/debug/cpufreq/cpuX
If many CPUs share only one cpufreq policy, other CPUs(except for first CPU)
create a symbolic link for debugfs directory of CPU0.
- link: /sys/kernel/debug/cpufreq/cpu[1-(N-1)] -> /sys/kernel/debug/cpufreq/cpu0
And then cpufreq may need to create debugfs specific file below of debugfs
directory of cpufreq. (e.g., /sys/kernel/debug/cpufreq/cpu0/load_table)
Signed-off-by: Chanwoo Choi <cw00.choi@xxxxxxxxxxx>
Signed-off-by: Kyungmin Park <kyungmin.park@xxxxxxxxxxx>
Signed-off-by: Myungjoo Ham <myungjoo.ham@xxxxxxxxxxx>
---
Changes since v5:
- Refactoring patch v4
- Create again symbolic link of debugfs directory when first CPU dev is removed
(In this case, many CPUs share only one cpufreq policy)
drivers/cpufreq/cpufreq.c | 177 ++++++++++++++++++++++++++++++++++++++++++++++
include/linux/cpufreq.h | 1 +
2 files changed, 178 insertions(+)
diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
index 2d53f47..924d654 100644
--- a/drivers/cpufreq/cpufreq.c
+++ b/drivers/cpufreq/cpufreq.c
@@ -23,6 +23,7 @@
#include <linux/notifier.h>
#include <linux/cpufreq.h>
#include <linux/delay.h>
+#include <linux/debugfs.h>
#include <linux/interrupt.h>
#include <linux/spinlock.h>
#include <linux/device.h>
@@ -703,6 +704,164 @@ static struct kobj_type ktype_cpufreq = {
.release = cpufreq_sysfs_release,
};
+#ifdef CONFIG_CPU_FREQ_STAT
+/* The cpufreq_debugfs is used to create debugfs root directory for CPUFreq. */
+static struct dentry *cpufreq_debugfs;
+
+static int cpufreq_create_debugfs_dir(struct cpufreq_policy *policy,
+ struct device *dev)
+{
+ char name[CPUFREQ_NAME_LEN];
+ unsigned int cpus, size, idx;
+
+ if (!cpufreq_debugfs)
+ return -EINVAL;
+
+ cpus = cpumask_weight(policy->cpus);
+ idx = cpus > 1 ? policy->cpu : 0;
+
+ size = sizeof(struct dentry*) * cpus;
+ policy->cpu_debugfs = devm_kzalloc(dev, size, GFP_KERNEL);
+ if (!policy->cpu_debugfs) {
+ pr_err("allocating debugfs memory failed\n");
+ return -ENOMEM;
+ }
+
+ sprintf(name, "cpu%d", policy->cpu);
+ policy->cpu_debugfs[idx] = debugfs_create_dir(name, cpufreq_debugfs);
+ if (!policy->cpu_debugfs[idx]) {
+ pr_err("creating debugfs directory failed\n");
+ return -ENODEV;
+ }
+
+ return 0;
+}
+
+static int cpufreq_create_debugfs_symlink(struct cpufreq_policy *policy,
+ unsigned int src_cpu,
+ unsigned int dest_cpu)
+{
+ char symlink_name[CPUFREQ_NAME_LEN];
+ char target_name[CPUFREQ_NAME_LEN];
+
+ if (!cpufreq_debugfs)
+ return -EINVAL;
+
+ if (!policy->cpu_debugfs[src_cpu])
+ return -EINVAL;
+
+ sprintf(symlink_name, "cpu%d", dest_cpu);
+ sprintf(target_name, "./cpu%d", src_cpu);
+ policy->cpu_debugfs[dest_cpu] = debugfs_create_symlink(
+ symlink_name,
+ cpufreq_debugfs,
+ target_name);
+ if (!policy->cpu_debugfs[dest_cpu]) {
+ pr_err("creating debugfs symlink failed\n");
+ return -ENODEV;
+ }
+
+ return 0;
+}
+
+static void cpufreq_remove_debugfs_dir(struct cpufreq_policy *policy,
+ unsigned int cpu)
+{
+ unsigned int idx = cpumask_weight(policy->cpus) > 1 ? cpu : 0;
+
+ if (!policy->cpu_debugfs[idx])
+ return;
+
+ debugfs_remove_recursive(policy->cpu_debugfs[idx]);
+}
+
+static void cpufreq_move_debugfs_dir(struct cpufreq_policy *policy,
+ unsigned int new_cpu)
+{
+ struct dentry *old_entry, *new_entry;
+ char new_dir_name[CPUFREQ_NAME_LEN];
+ unsigned int j, old_cpu = policy->cpu;
+
+ if (!policy->cpu_debugfs[new_cpu])
+ return;
+
+ /*
+ * Remove symbolic link of debugfs directory except for debugfs
+ * directory of old_cpu.
+ */
+ for_each_present_cpu(j) {
+ if (old_cpu == j)
+ continue;
+
+ debugfs_remove(policy->cpu_debugfs[j]);
+ }
+
+ /*
+ * Change debugfs directory name from as following:
+ * - old debugfs dir name : /sys/kernel/debugfs/cpufreq/cpu${old_cpu}
+ * - new debugfs dir name : /sys/kernel/debugfs/cpufreq/cpu${new_cpu}
+ */
+ sprintf(new_dir_name, "cpu%d", new_cpu);
+ old_entry = policy->cpu_debugfs[old_cpu];
+ new_entry = debugfs_rename(cpufreq_debugfs, old_entry,
+ cpufreq_debugfs, new_dir_name);
+ if (!new_entry) {
+ pr_err("changing debugfs directory name failed\n");
+ goto err_rename;
+ }
+
+ policy->cpu_debugfs[new_cpu] = new_entry;
+ policy->cpu_debugfs[old_cpu] = NULL;
+
+ /* Create again symbolic link of debugfs directory */
+ for_each_present_cpu(j) {
+ if (new_cpu == j)
+ continue;
+
+ cpufreq_create_debugfs_symlink(policy, new_cpu, j);
+ }
+
+ return;
+
+err_rename:
+ for_each_present_cpu(j) {
+ if (old_cpu == j)
+ continue;
+
+ cpufreq_create_debugfs_symlink(policy, old_cpu, j);
+ }
+}
+
+static int cpufreq_create_debugfs(void)
+{
+ cpufreq_debugfs = debugfs_create_dir("cpufreq", NULL);
+ if (!cpufreq_debugfs) {
+ pr_err("creating debugfs root failed\n");
+ return -ENODEV;
+ }
+
+ return 0;
+}
+
+static void cpufreq_remove_debugfs(void)
+{
+ if (cpufreq_debugfs)
+ debugfs_remove_recursive(cpufreq_debugfs);
+}
+#else
+static int cpufreq_create_debugfs_dir(struct cpufreq_policy *policy,
+ struct device *dev) { return 0; }
+static int cpufreq_create_debugfs_symlink(struct cpufreq_policy *policy,
+ unsigned int src_cpu,
+ unsigned int dest_cpu) { return 0;}
+static void cpufreq_remove_debugfs_dir(struct cpufreq_policy *policy,
+ unsigned int cpu) { }
+static void cpufreq_move_debugfs_dir(struct cpufreq_policy *policy,
+ unsigned int new_cpu) { }
+static int cpufreq_create_debugfs(void) { return 0; }
+static void cpufreq_remove_debugfs(void) { }
+#endif
+
/* symlink affected CPUs */
static int cpufreq_add_dev_symlink(unsigned int cpu,
struct cpufreq_policy *policy)
@@ -726,6 +885,8 @@ static int cpufreq_add_dev_symlink(unsigned int cpu,
cpufreq_cpu_put(managed_policy);
return ret;
}
+
+ cpufreq_create_debugfs_symlink(policy, cpu, j);
}
return ret;
}
@@ -777,6 +938,9 @@ static int cpufreq_add_dev_interface(unsigned int cpu,
}
write_unlock_irqrestore(&cpufreq_driver_lock, flags);
+ /* prepare interface data for debugfs */
+ cpufreq_create_debugfs_dir(policy, dev);
+
ret = cpufreq_add_dev_symlink(cpu, policy);
if (ret)
goto err_out_kobj_put;
@@ -839,6 +1003,8 @@ static int cpufreq_add_policy_cpu(unsigned int cpu, unsigned int sibling,
return ret;
}
+ cpufreq_create_debugfs_symlink(policy, sibling, cpu);
+
return 0;
}
#endif
@@ -1046,6 +1212,7 @@ static int __cpufreq_remove_dev(struct device *dev, struct subsys_interface *sif
if (cpu != data->cpu) {
sysfs_remove_link(&dev->kobj, "cpufreq");
+ cpufreq_remove_debugfs_dir(data, cpu);
} else if (cpus > 1) {
/* first sibling now owns the new sysfs dir */
cpu_dev = get_cpu_device(cpumask_first(data->cpus));
@@ -1068,6 +1235,8 @@ static int __cpufreq_remove_dev(struct device *dev, struct subsys_interface *sif
return -EINVAL;
}
+ cpufreq_move_debugfs_dir(data, cpu_dev->id);
+
WARN_ON(lock_policy_rwsem_write(cpu));
update_policy_cpu(data, cpu_dev->id);
unlock_policy_rwsem_write(cpu);
@@ -1089,6 +1258,8 @@ static int __cpufreq_remove_dev(struct device *dev, struct subsys_interface *sif
unlock_policy_rwsem_read(cpu);
kobject_put(kobj);
+ cpufreq_remove_debugfs_dir(data, cpu);
+
/* we need to make sure that the underlying kobj is actually
* not referenced anymore by anybody before we proceed with
* unloading.
@@ -1894,6 +2065,8 @@ int cpufreq_register_driver(struct cpufreq_driver *driver_data)
cpufreq_driver = driver_data;
write_unlock_irqrestore(&cpufreq_driver_lock, flags);
+ cpufreq_create_debugfs();
+
ret = subsys_interface_register(&cpufreq_interface);
if (ret)
goto err_null_driver;
@@ -1918,12 +2091,14 @@ int cpufreq_register_driver(struct cpufreq_driver *driver_data)
}
register_hotcpu_notifier(&cpufreq_cpu_notifier);
+
pr_debug("driver %s up and running\n", driver_data->name);
return 0;
err_if_unreg:
subsys_interface_unregister(&cpufreq_interface);
err_null_driver:
+ cpufreq_remove_debugfs();
write_lock_irqsave(&cpufreq_driver_lock, flags);
cpufreq_driver = NULL;
write_unlock_irqrestore(&cpufreq_driver_lock, flags);
@@ -1949,6 +2124,8 @@ int cpufreq_unregister_driver(struct cpufreq_driver *driver)
pr_debug("unregistering driver %s\n", driver->name);
+ cpufreq_remove_debugfs();
+
subsys_interface_unregister(&cpufreq_interface);
unregister_hotcpu_notifier(&cpufreq_cpu_notifier);
diff --git a/include/linux/cpufreq.h b/include/linux/cpufreq.h
index 037d36a..825f379 100644
--- a/include/linux/cpufreq.h
+++ b/include/linux/cpufreq.h
@@ -115,6 +115,7 @@ struct cpufreq_policy {
struct kobject kobj;
struct completion kobj_unregister;
+ struct dentry **cpu_debugfs;
};
#define CPUFREQ_ADJUST (0)
--
1.8.0
--
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