regulator: add get_status()

Based on previous LKML discussions:

 * Update docs for regulator sysfs class attributes to highlight
   the fact that all current attributes are intended to be control
   inputs, including notably "state" and "opmode" which previously
   implied otherwise.

 * Define a new regulator driver get_status() method, which is the
   first method reporting regulator outputs instead of inputs.
   It can report on/off and error status; or instead of simply
   "on", report the actual operating mode.

For the moment, this is a sysfs-only interface, not accessible to
regulator clients.  Such clients can use the current notification
interfaces to detect errors, if the regulator reports them.

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Liam Girdwood <lrg@slimlogic.co.uk>

1 files changed, 46 insertions, 0 deletions

diff --git a/drivers/regulator/core.c b/drivers/regulator/core.c
index f511a406fcaa..0ff95c3ccf5b 100644
--- a/drivers/regulator/core.c
+++ b/drivers/regulator/core.c
@@ -312,6 +312,47 @@ static ssize_t regulator_state_show(struct device *dev,
 }
 static DEVICE_ATTR(state, 0444, regulator_state_show, NULL);
 
+static ssize_t regulator_status_show(struct device *dev,
+				   struct device_attribute *attr, char *buf)
+{
+	struct regulator_dev *rdev = dev_get_drvdata(dev);
+	int status;
+	char *label;
+
+	status = rdev->desc->ops->get_status(rdev);
+	if (status < 0)
+		return status;
+
+	switch (status) {
+	case REGULATOR_STATUS_OFF:
+		label = "off";
+		break;
+	case REGULATOR_STATUS_ON:
+		label = "on";
+		break;
+	case REGULATOR_STATUS_ERROR:
+		label = "error";
+		break;
+	case REGULATOR_STATUS_FAST:
+		label = "fast";
+		break;
+	case REGULATOR_STATUS_NORMAL:
+		label = "normal";
+		break;
+	case REGULATOR_STATUS_IDLE:
+		label = "idle";
+		break;
+	case REGULATOR_STATUS_STANDBY:
+		label = "standby";
+		break;
+	default:
+		return -ERANGE;
+	}
+
+	return sprintf(buf, "%s\n", label);
+}
+static DEVICE_ATTR(status, 0444, regulator_status_show, NULL);
+
 static ssize_t regulator_min_uA_show(struct device *dev,
 				    struct device_attribute *attr, char *buf)
 {
@@ -1744,6 +1785,11 @@ static int add_regulator_attributes(struct regulator_dev *rdev)
 		if (status < 0)
 			return status;
 	}
+	if (ops->get_status) {
+		status = device_create_file(dev, &dev_attr_status);
+		if (status < 0)
+			return status;
+	}
 
 	/* some attributes are type-specific */
 	if (rdev->desc->type == REGULATOR_CURRENT) {