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Message-Id: <20180628114043.24724-5-quentin.perret@arm.com>
Date: Thu, 28 Jun 2018 12:40:35 +0100
From: Quentin Perret <quentin.perret@....com>
To: peterz@...radead.org, rjw@...ysocki.net,
linux-kernel@...r.kernel.org, linux-pm@...r.kernel.org
Cc: gregkh@...uxfoundation.org, mingo@...hat.com,
dietmar.eggemann@....com, morten.rasmussen@....com,
chris.redpath@....com, patrick.bellasi@....com,
valentin.schneider@....com, vincent.guittot@...aro.org,
thara.gopinath@...aro.org, viresh.kumar@...aro.org,
tkjos@...gle.com, joel@...lfernandes.org, smuckle@...gle.com,
adharmap@...cinc.com, skannan@...cinc.com, pkondeti@...eaurora.org,
juri.lelli@...hat.com, edubezval@...il.com,
srinivas.pandruvada@...ux.intel.com, currojerez@...eup.net,
javi.merino@...nel.org, quentin.perret@....com
Subject: [RFC PATCH v4 04/12] PM / EM: Expose the Energy Model in sysfs
Expose the Energy Model (read-only) of all frequency domains in sysfs
for convenience. To do so, add a kobject 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 <peterz@...radead.org>
Cc: "Rafael J. Wysocki" <rjw@...ysocki.net>
Signed-off-by: Quentin Perret <quentin.perret@....com>
---
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 88c2f0b9bcb3..0f109cefed62 100644
--- a/include/linux/energy_model.h
+++ b/include/linux/energy_model.h
@@ -23,6 +23,7 @@ struct em_cs_table {
struct em_freq_domain {
struct em_cs_table *cs_table; /* Capacity state table, RCU-protected */
+ struct kobject kobj;
unsigned long cpus[0]; /* CPUs of the frequency domain. */
};
diff --git a/kernel/power/energy_model.c b/kernel/power/energy_model.c
index 08ce4035a6d6..53456147e656 100644
--- a/kernel/power/energy_model.c
+++ b/kernel/power/energy_model.c
@@ -23,6 +23,86 @@ static DEFINE_PER_CPU(struct em_freq_domain *, em_data);
*/
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(to_cpumask(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_cs)
{
struct em_cs_table *cs_table;
@@ -142,6 +222,11 @@ static struct em_freq_domain *em_create_fd(cpumask_t *span, int nr_states,
/* Copy the span of the frequency domain */
cpumask_copy(to_cpumask(fd->cpus), span);
+ ret = kobject_init_and_add(&fd->kobj, &ktype_em_fd, em_kobject,
+ "fd%u", cpu);
+ if (ret)
+ pr_err("fd%d: failed kobject_init_and_add(): %d\n", cpu, ret);
+
return fd;
free_cs_table:
@@ -247,6 +332,15 @@ 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 (READ_ONCE(per_cpu(em_data, cpu))) {
--
2.17.1
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