leds-lp55xx: add new lp55xx_register_sysfs() for the firmware interface

 LP55xx family chips have internal program memory which run various patterns.
 Using this memory, LEDs continue on blinking/dimming without continuous I2C
 commands. That means the I2C HOST can be entered into sleep once the memory
 is updated.

 An application can get hex data from a file and write them into
 the program memory through the I2C. This is general firwmare interface.

 This patch is the initial step for adding the firmware interface.
Signed-off-by: Milo(Woogyom) Kim <milo.kim@ti.com>
Signed-off-by: Bryan Wu <cooloney@gmail.com>

drivers/leds/leds-lp55xx-common.c

@@ -197,6 +197,14 @@ static int lp55xx_init_led(struct lp55xx_led *led,
 	return 0;
 }
 
+static struct attribute *lp55xx_engine_attributes[] = {
+	NULL,
+};
+
+static const struct attribute_group lp55xx_engine_attr_group = {
+	.attrs = lp55xx_engine_attributes,
+};
+
 int lp55xx_write(struct lp55xx_chip *chip, u8 reg, u8 val)
 {
 	return i2c_smbus_write_byte_data(chip->cl, reg, val);
@@ -365,6 +373,14 @@ void lp55xx_unregister_leds(struct lp55xx_led *led, struct lp55xx_chip *chip)
 }
 EXPORT_SYMBOL_GPL(lp55xx_unregister_leds);
 
+int lp55xx_register_sysfs(struct lp55xx_chip *chip)
+{
+	struct device *dev = &chip->cl->dev;
+
+	return sysfs_create_group(&dev->kobj, &lp55xx_engine_attr_group);
+}
+EXPORT_SYMBOL_GPL(lp55xx_register_sysfs);
+
 MODULE_AUTHOR("Milo Kim <milo.kim@ti.com>");
 MODULE_DESCRIPTION("LP55xx Common Driver");
 MODULE_LICENSE("GPL");

drivers/leds/leds-lp55xx-common.h

@@ -103,4 +103,8 @@ extern int lp55xx_register_leds(struct lp55xx_led *led,
 				struct lp55xx_chip *chip);
 extern void lp55xx_unregister_leds(struct lp55xx_led *led,
 				struct lp55xx_chip *chip);
+
+/* common device attributes functions */
+extern int lp55xx_register_sysfs(struct lp55xx_chip *chip);
+
 #endif /* _LEDS_LP55XX_COMMON_H */