gpiolib: add names file in gpio chip sysfs.

[ben]

Add a 'names' file to the sysfs entries for each chip to show which
have names.

Signed-off-by: Ben Dooks <ben@xxxxxxxxxxxx>
CC: David Brownell <dbrownell@xxxxxxxxxxxxxxxxxxxxx>

---
 drivers/gpio/gpiolib.c |   21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)

Index: b/drivers/gpio/gpiolib.c
===================================================================
--- a/drivers/gpio/gpiolib.c	2009-08-03 17:51:40.000000000 +0100
+++ b/drivers/gpio/gpiolib.c	2009-08-03 17:53:04.000000000 +0100
@@ -303,6 +303,7 @@ static const struct attribute_group gpio
  *   /base ... matching gpio_chip.base (N)
  *   /label ... matching gpio_chip.label
  *   /ngpio ... matching gpio_chip.ngpio
+ *   /names ... matching gpio_chip.names
  */
 
 static ssize_t chip_base_show(struct device *dev,
@@ -332,10 +333,30 @@ static ssize_t chip_ngpio_show(struct de
 }
 static DEVICE_ATTR(ngpio, 0444, chip_ngpio_show, NULL);
 
+static ssize_t chip_names_show(struct device *dev,
+			       struct device_attribute *attr, char *buf)
+{
+	const struct gpio_chip*chip = dev_get_drvdata(dev);
+	char **names = chip->names;
+	int ptr = 0;
+	int name;
+
+	if (!names)
+		return -EINVAL;
+
+	for (name = 0; name < chip->ngpio && ptr < PAGE_SIZE; name++)
+		ptr += snprintf(buf + ptr, PAGE_SIZE - ptr,
+				"%s\n", names[name] ? names[name] : "");
+
+	return ptr;
+}
+DEVICE_ATTR(names, 0444, chip_names_show, NULL);
+
 static const struct attribute *gpiochip_attrs[] = {
 	&dev_attr_base.attr,
 	&dev_attr_label.attr,
 	&dev_attr_ngpio.attr,
+	&dev_attr_names.attr,
 	NULL,
 };
 

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