[PATCH 2/3] pda_power: add support for writeable properties

From: Daniel Mack
Date: Tue May 18 2010 - 15:50:44 EST


This patch adds support for writeable power supply properties and
exposes them as writeable to sysfs.

A power supply implementation must implement two new function calls in
order to use that feature:

int set_property(struct power_supply *psy,
enum power_supply_property psp,
const union power_supply_propval *val);

int property_is_writeable(struct power_supply *psy,
enum power_supply_property psp);

Signed-off-by: Daniel Mack <daniel@xxxxxxxx>
Cc: Anton Vorontsov <cbou@xxxxxxx>
Cc: David Woodhouse <dwmw2@xxxxxxxxxxxxx>
Cc: Alexey Starikovskiy <astarikovskiy@xxxxxxx>
Cc: Len Brown <len.brown@xxxxxxxxx>
Cc: Mark Brown <broonie@xxxxxxxxxxxxxxxxxxxxxxxxxxx>
Cc: Matt Reimer <mreimer@xxxxxxxx>
Cc: Evgeniy Polyakov <zbr@xxxxxxxxxxx>
Cc: Tejun Heo <tj@xxxxxxxxxx>
---
drivers/power/power_supply_sysfs.c | 38 +++++++++++++++++++++++++++++++++--
include/linux/power_supply.h | 5 ++++
2 files changed, 40 insertions(+), 3 deletions(-)

diff --git a/drivers/power/power_supply_sysfs.c b/drivers/power/power_supply_sysfs.c
index 6eb49ef..6a779fe 100644
--- a/drivers/power/power_supply_sysfs.c
+++ b/drivers/power/power_supply_sysfs.c
@@ -33,7 +33,7 @@
{ \
.attr = { .name = #_name }, \
.show = power_supply_show_property, \
- .store = NULL, \
+ .store = power_supply_store_property, \
}

static struct device_attribute power_supply_attrs[];
@@ -99,6 +99,29 @@ static ssize_t power_supply_show_property(struct device *dev,
return sprintf(buf, "%d\n", value.intval);
}

+static ssize_t power_supply_store_property(struct device *dev,
+ struct device_attribute *attr,
+ const char *buf, size_t count) {
+ ssize_t ret;
+ struct power_supply *psy = dev_get_drvdata(dev);
+ const ptrdiff_t off = attr - power_supply_attrs;
+ union power_supply_propval value;
+ long long_val;
+
+ /* TODO: support other types than int */
+ ret = strict_strtol(buf, 10, &long_val);
+ if (ret < 0)
+ return ret;
+
+ value.intval = long_val;
+
+ ret = psy->set_property(psy, off, &value);
+ if (ret < 0)
+ return ret;
+
+ return count;
+}
+
/* Must be in the same order as POWER_SUPPLY_PROP_* */
static struct device_attribute power_supply_attrs[] = {
/* Properties of type `int' */
@@ -159,8 +182,17 @@ static mode_t power_supply_attr_is_visible(struct kobject *kobj,
int i;

for (i = 0; i < psy->num_properties; i++) {
- if (psy->properties[i] == attrno)
- return 0444;
+ int property = psy->properties[i];
+
+ if (property == attrno) {
+ mode_t mode = S_IRUSR | S_IRGRP | S_IROTH;
+
+ if (psy->property_is_writeable &&
+ psy->property_is_writeable(psy, property) > 0)
+ mode |= S_IWUSR;
+
+ return mode;
+ }
}

return 0;
diff --git a/include/linux/power_supply.h b/include/linux/power_supply.h
index c5f73a3..30083a8 100644
--- a/include/linux/power_supply.h
+++ b/include/linux/power_supply.h
@@ -145,6 +145,11 @@ struct power_supply {
int (*get_property)(struct power_supply *psy,
enum power_supply_property psp,
union power_supply_propval *val);
+ int (*set_property)(struct power_supply *psy,
+ enum power_supply_property psp,
+ const union power_supply_propval *val);
+ int (*property_is_writeable)(struct power_supply *psy,
+ enum power_supply_property psp);
void (*external_power_changed)(struct power_supply *psy);
void (*set_charged)(struct power_supply *psy);

--
1.7.1

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