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Date: Thu, 29 Sep 2011 21:18:49 +0900
From: MyungJoo Ham <myungjoo.ham@...sung.com>
To: LKML <linux-kernel@...r.kernel.org>,
linux-pm@...ts.linux-foundation.org
Cc: Pavel Machek <pavel@....cz>, "Rafael J. Wysocki" <rjw@...k.pl>,
Greg Kroah-Hartman <gregkh@...e.de>,
Kevin Hilman <khilman@...com>, Nishanth Menon <nm@...com>,
Kyungmin Park <kyungmin.park@...sung.com>,
Colin Cross <ccross@...gle.com>,
Thomas Gleixner <tglx@...utronix.de>,
Mike Turquette <mturquette@...com>, myungjoo.ham@...il.com
Subject: [PATCH v13 3/4] PM / devfreq: add common sysfs interfaces
Device specific sysfs interface /sys/devices/.../power/devfreq_*
- governor R: name of governor
- cur_freq R: current frequency
- polling_interval R: polling interval in ms given with devfreq profile
W: update polling interval.
- central_polling R: 1 if polling is managed by devfreq framework
Signed-off-by: MyungJoo Ham <myungjoo.ham@...sung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@...sung.com>
Reviewed-by: Mike Turquette <mturquette@...com>
Acked-by: Kevin Hilman <khilman@...com>
--
Changes from v11
- Revised sysfs function style
- Revised lock usages in store_polling_interval()
- Moved "devfreq_class->dev_attrs = devfreq_attrs;" statement from 2/4
to 3/4 patch.
Changes from v10
- removed min_freq, max_freq as OPP dependency is removed and devfreq
object does not aware of such values.
Changes from v9
- removed find_devfreq loop in sysfs functions
- moved ABI document location due to sysfs location change
- removed unnecessary locks
Changes from v8
- applied per-devfreq locking mechanism
Changes from v7
- removed set_freq from the common devfreq interface
- added get_devfreq, a mutex-protected wrapper for find_device_devfreq
(for sysfs interfaces and later with governor-support)
- corrected ABI documentation.
Changes from v6
- poling_interval is writable.
Changes from v5
- updated devferq_update usage.
Changes from v4
- removed system-wide sysfs interface
- removed tickling sysfs interface
- added set_freq for userspace governor (and any other governors that
require user input)
Changes from v3
- corrected sysfs API usage
- corrected error messages
- moved sysfs entry location
- added sysfs entries
Changes from v2
- add ABI entries for devfreq sysfs interface
---
Documentation/ABI/testing/sysfs-class-devfreq | 44 ++++++++++++++++
drivers/devfreq/devfreq.c | 69 +++++++++++++++++++++++++
2 files changed, 113 insertions(+), 0 deletions(-)
create mode 100644 Documentation/ABI/testing/sysfs-class-devfreq
diff --git a/Documentation/ABI/testing/sysfs-class-devfreq b/Documentation/ABI/testing/sysfs-class-devfreq
new file mode 100644
index 0000000..0ec855f
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-class-devfreq
@@ -0,0 +1,44 @@
+What: /sys/class/devfreq/.../
+Date: September 2011
+Contact: MyungJoo Ham <myungjoo.ham@...sung.com>
+Description:
+ Provide a place in sysfs for the devfreq objects.
+ This allows accessing various devfreq specific variables.
+ The name of devfreq object denoted as ... is same as the
+ name of device using devfreq.
+
+What: /sys/class/devfreq/.../governor
+Date: September 2011
+Contact: MyungJoo Ham <myungjoo.ham@...sung.com>
+Description:
+ The /sys/class/devfreq/.../governor shows the name of the
+ governor used by the corresponding devfreq object.
+
+What: /sys/class/devfreq/.../cur_freq
+Date: September 2011
+Contact: MyungJoo Ham <myungjoo.ham@...sung.com>
+Description:
+ The /sys/class/devfreq/.../cur_freq shows the current
+ frequency of the corresponding devfreq object.
+
+What: /sys/class/devfreq/.../central_polling
+Date: September 2011
+Contact: MyungJoo Ham <myungjoo.ham@...sung.com>
+Description:
+ The /sys/class/devfreq/.../central_polling shows whether
+ the devfreq ojbect is using devfreq-provided central
+ polling mechanism or not.
+
+What: /sys/class/devfreq/.../polling_interval
+Date: September 2011
+Contact: MyungJoo Ham <myungjoo.ham@...sung.com>
+Description:
+ The /sys/class/devfreq/.../polling_interval shows and sets
+ the requested polling interval of the corresponding devfreq
+ object. The values are represented in ms. If the value is
+ less than 1 jiffy, it is considered to be 0, which means
+ no polling. This value is meaningless if the governor is
+ not polling; thus. If the governor is not using
+ devfreq-provided central polling
+ (/sys/class/devfreq/.../central_polling is 0), this value
+ may be useless.
diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c
index 8ecab66..fe65bc4 100644
--- a/drivers/devfreq/devfreq.c
+++ b/drivers/devfreq/devfreq.c
@@ -437,6 +437,74 @@ int devfreq_remove_device(struct devfreq *devfreq)
return 0;
}
+static ssize_t show_governor(struct device *dev,
+ struct device_attribute *attr, char *buf)
+{
+ return sprintf(buf, "%s\n", to_devfreq(dev)->governor->name);
+}
+
+static ssize_t show_freq(struct device *dev,
+ struct device_attribute *attr, char *buf)
+{
+ return sprintf(buf, "%lu\n", to_devfreq(dev)->previous_freq);
+}
+
+static ssize_t show_polling_interval(struct device *dev,
+ struct device_attribute *attr, char *buf)
+{
+ return sprintf(buf, "%d\n", to_devfreq(dev)->profile->polling_ms);
+}
+
+static ssize_t store_polling_interval(struct device *dev,
+ struct device_attribute *attr,
+ const char *buf, size_t count)
+{
+ struct devfreq *df = to_devfreq(dev);
+ unsigned int value;
+ int ret;
+
+ ret = sscanf(buf, "%u", &value);
+ if (ret != 1)
+ goto out;
+
+ mutex_lock(&df->lock);
+ df->profile->polling_ms = value;
+ df->next_polling = df->polling_jiffies
+ = msecs_to_jiffies(value);
+ mutex_unlock(&df->lock);
+
+ ret = count;
+
+ if (df->governor->no_central_polling)
+ goto out;
+
+ mutex_lock(&devfreq_list_lock);
+ if (df->next_polling > 0 && !polling) {
+ polling = true;
+ queue_delayed_work(devfreq_wq, &devfreq_work,
+ df->next_polling);
+ }
+ mutex_unlock(&devfreq_list_lock);
+out:
+ return ret;
+}
+
+static ssize_t show_central_polling(struct device *dev,
+ struct device_attribute *attr, char *buf)
+{
+ return sprintf(buf, "%d\n",
+ !to_devfreq(dev)->governor->no_central_polling);
+}
+
+static struct device_attribute devfreq_attrs[] = {
+ __ATTR(governor, S_IRUGO, show_governor, NULL),
+ __ATTR(cur_freq, S_IRUGO, show_freq, NULL),
+ __ATTR(central_polling, S_IRUGO, show_central_polling, NULL),
+ __ATTR(polling_interval, S_IRUGO | S_IWUSR, show_polling_interval,
+ store_polling_interval),
+ { },
+};
+
/**
* devfreq_start_polling() - Initialize data structure for devfreq framework and
* start polling registered devfreq devices.
@@ -461,6 +529,7 @@ static int __init devfreq_init(void)
pr_err("%s: couldn't create class\n", __FILE__);
return PTR_ERR(devfreq_class);
}
+ devfreq_class->dev_attrs = devfreq_attrs;
return 0;
}
subsys_initcall(devfreq_init);
--
1.7.4.1
--
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