regulator: Display in use regulators in sysfs

Please excuse any poor formatting that may occur, as this is copy-paste into my mailer, but what do you think of this idea?

To locate a consumer that currently holds a regulattor, a new sysfs entry is created. The consumer are published in /sys/class/regulator/regulator.<#>/use.

---
 drivers/regulator/core.c |   36 ++++++++++++++++++++++++++++++++++++
 1 file changed, 36 insertions(+)

index 046fb1b..40fd150 100644
@@ -81,6 +81,7 @@ struct regulator {
   struct device_attribute dev_attr;
   struct regulator_dev *rdev;
   struct dentry *debugfs;
+  int use;
 };
 
 static int _regulator_is_enabled(struct regulator_dev *rdev);

@@ -602,6 +603,32 @@ static ssize_t

regulator_suspend_standby_state_show(struct device *dev,
static DEVICE_ATTR(suspend_standby_state, 0444,
regulator_suspend_standby_state_show,

					   NULL);

+static ssize_t regulator_use_show(struct device *dev,
+ struct device_attribute *attr, char *buf)
+{
+ struct regulator_dev *rdev = dev_get_drvdata(dev);
+ struct regulator *reg;
+ size_t size = 0;
+
+ if (rdev->use_count == 0)
+ return sprintf(buf, "no users\n");
+
+ list_for_each_entry(reg, &rdev->consumer_list, list) {
+ if (!reg->use)
+ continue;
+
+ if (reg->dev != NULL)
+ size += sprintf((buf + size), "%s (%d) ",
+ dev_name(reg->dev), reg->use);
+ else
+ size += sprintf((buf + size), "unknown (%d) ",
+ reg->use);
+ }
+ size += sprintf((buf + size), "\n");
+
+ return size;
+}
+static DEVICE_ATTR(use, 0444, regulator_use_show, NULL);

/*
* These are the only attributes are present for all regulators.
@@ -1540,6 +1567,8 @@ int regulator_enable(struct regulator *regulator)

	if (ret != 0 && rdev->supply)

regulator_disable(rdev->supply);
+ else
+ regulator->use++;

	return ret;
 }
@@ -1613,6 +1642,9 @@ int regulator_disable(struct regulator
*regulator)
	if (ret == 0 && rdev->supply)

regulator_disable(rdev->supply);

+ if (ret == 0)
+ regulator->use--;
+

	return ret;

}
EXPORT_SYMBOL_GPL(regulator_disable);
@@ -2699,6 +2731,10 @@ static int add_regulator_attributes(struct
regulator_dev *rdev)
struct regulator_ops *ops = rdev->desc->ops;
int status = 0;

+ status = device_create_file(dev, &dev_attr_use);
+ if (status < 0)
+ dev_warn(dev, "Create sysfs file \"use\" failed");
+

	/* some attributes need specific methods to be displayed */
 	if ((ops->get_voltage && ops->get_voltage(rdev) >= 0) ||
 	    (ops->get_voltage_sel && ops->get_voltage_sel(rdev) >= 0))
	        {

Lee Jones
Linaro ST-Ericsson Landing Team Lead
Linaro.org │ Open source software for ARM SoCs
Follow Linaro: Facebook | Twitter | Blog

We call our reference counts use count but this was in fact the original design, the local reference counts got dropped due to David Brownell's forceful insistance :/

So I should pull the patch?

How do you feel about being able to access it via sysfs? Good or bad idea? If it's a good idea, I can always change the name of the variable?

Lee Jones
Linaro ST-Ericsson Landing Team Lead
Linaro.org │ Open source software for ARM SoCs
Follow Linaro: Facebook | Twitter | Blog

Not sure what you mean by pull; a stright revert won't work.

That or debugfs.

Sorry, perhaps I should have been clearer.

Is the patch any good, or should I throw it in the bin (pull it)?

So the premise of the patch is good and is worth updating and upstreaming?

Lee Jones
Linaro ST-Ericsson Landing Team Lead
Linaro.org │ Open source software for ARM SoCs
Follow Linaro: Facebook | Twitter | Blog

Yes.