This exposes the Energy Model (read-only) of all frequency domains in
sysfs for convenience. To do so, a parent kobject is added to the CPU
subsystem under the umbrella of which a kobject for each frequency
domain is attached.
The resulting hierarchy is as follows for a platform with two frequency
domains for example:
/sys/devices/system/cpu/energy_model
├── fd0
│ ├── capacity
│ ├── cpus
│ ├── frequency
│ └── power
└── fd4
├── capacity
├── cpus
├── frequency
└── power
In this implementation, the kobject abstraction is only used as a
convenient way of exposing data to sysfs. However, it could also be
used in the future to allocate and release frequency domains in a more
dynamic way using reference counting.
Cc: Peter Zijlstra <[email protected]>
Cc: "Rafael J. Wysocki" <[email protected]>
Signed-off-by: Quentin Perret <[email protected]>
---
include/linux/energy_model.h | 1 +
kernel/power/energy_model.c | 94 ++++++++++++++++++++++++++++++++++++
2 files changed, 95 insertions(+)
diff --git a/include/linux/energy_model.h b/include/linux/energy_model.h
index edde888852ba..ed79903a9721 100644
--- a/include/linux/energy_model.h
+++ b/include/linux/energy_model.h
@@ -24,6 +24,7 @@ struct em_cs_table {
struct em_freq_domain {
struct em_cs_table *cs_table;
cpumask_t cpus;
+ struct kobject kobj;
};
struct em_data_callback {
diff --git a/kernel/power/energy_model.c b/kernel/power/energy_model.c
index a2eece7007a8..6ad53f1cf7e6 100644
--- a/kernel/power/energy_model.c
+++ b/kernel/power/energy_model.c
@@ -29,6 +29,86 @@ static DEFINE_RWLOCK(em_data_lock);
*/
static DEFINE_MUTEX(em_fd_mutex);
+static struct kobject *em_kobject;
+
+/* Getters for the attributes of em_freq_domain objects */
+struct em_fd_attr {
+ struct attribute attr;
+ ssize_t (*show)(struct em_freq_domain *fd, char *buf);
+ ssize_t (*store)(struct em_freq_domain *fd, const char *buf, size_t s);
+};
+
+#define EM_ATTR_LEN 13
+#define show_table_attr(_attr) \
+static ssize_t show_##_attr(struct em_freq_domain *fd, char *buf) \
+{ \
+ ssize_t cnt = 0; \
+ int i; \
+ struct em_cs_table *table; \
+ rcu_read_lock(); \
+ table = rcu_dereference(fd->cs_table);\
+ for (i = 0; i < table->nr_cap_states; i++) { \
+ if (cnt >= (ssize_t) (PAGE_SIZE / sizeof(char) \
+ - (EM_ATTR_LEN + 2))) \
+ goto out; \
+ cnt += scnprintf(&buf[cnt], EM_ATTR_LEN + 1, "%lu ", \
+ table->state[i]._attr); \
+ } \
+out: \
+ rcu_read_unlock(); \
+ cnt += sprintf(&buf[cnt], "\n"); \
+ return cnt; \
+}
+
+show_table_attr(power);
+show_table_attr(frequency);
+show_table_attr(capacity);
+
+static ssize_t show_cpus(struct em_freq_domain *fd, char *buf)
+{
+ return sprintf(buf, "%*pbl\n", cpumask_pr_args(&fd->cpus));
+}
+
+#define fd_attr(_name) em_fd_##_name##_attr
+#define define_fd_attr(_name) static struct em_fd_attr fd_attr(_name) = \
+ __ATTR(_name, 0444, show_##_name, NULL)
+
+define_fd_attr(power);
+define_fd_attr(frequency);
+define_fd_attr(capacity);
+define_fd_attr(cpus);
+
+static struct attribute *em_fd_default_attrs[] = {
+ &fd_attr(power).attr,
+ &fd_attr(frequency).attr,
+ &fd_attr(capacity).attr,
+ &fd_attr(cpus).attr,
+ NULL
+};
+
+#define to_fd(k) container_of(k, struct em_freq_domain, kobj)
+#define to_fd_attr(a) container_of(a, struct em_fd_attr, attr)
+
+static ssize_t show(struct kobject *kobj, struct attribute *attr, char *buf)
+{
+ struct em_freq_domain *fd = to_fd(kobj);
+ struct em_fd_attr *fd_attr = to_fd_attr(attr);
+ ssize_t ret;
+
+ ret = fd_attr->show(fd, buf);
+
+ return ret;
+}
+
+static const struct sysfs_ops em_fd_sysfs_ops = {
+ .show = show,
+};
+
+static struct kobj_type ktype_em_fd = {
+ .sysfs_ops = &em_fd_sysfs_ops,
+ .default_attrs = em_fd_default_attrs,
+};
+
static struct em_cs_table *alloc_cs_table(int nr_states)
{
struct em_cs_table *cs_table;
@@ -114,6 +194,11 @@ static struct em_freq_domain *em_create_fd(cpumask_t
*span, int nr_states,
}
fd_update_cs_table(fd->cs_table, cpu);
+ ret = kobject_init_and_add(&fd->kobj, &ktype_em_fd, em_kobject, "fd%u",
+ cpu);
+ if (ret)
+ pr_warn("%*pbl: failed kobject init\n", cpumask_pr_args(span));
+
return fd;
free_cs_table:
@@ -221,6 +306,15 @@ int em_register_freq_domain(cpumask_t *span, unsigned int
nr_states,
mutex_lock(&em_fd_mutex);
+ if (!em_kobject) {
+ em_kobject = kobject_create_and_add("energy_model",
+ &cpu_subsys.dev_root->kobj);
+ if (!em_kobject) {
+ ret = -ENODEV;
+ goto unlock;
+ }
+ }
+
/* Make sure we don't register again an existing domain. */
for_each_cpu(cpu, span) {
if (per_cpu(em_data, cpu)) {
--
2.17.0
