Messages in this thread Patch in this message | | | From | Quentin Perret <> | Subject | [RFC PATCH v3 04/10] PM / EM: Expose the Energy Model in sysfs | Date | Mon, 21 May 2018 15:24:59 +0100 |
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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 <peterz@infradead.org> Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net> Signed-off-by: Quentin Perret <quentin.perret@arm.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 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
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