leds: core: Add support for composing LED class device names

Add generic support for composing LED class device name. The newly
introduced led_compose_name() function composes device name according
to either <color:function> or <devicename:color:function> pattern,
depending on the configuration of initialization data.

Backward compatibility with in-driver hard-coded LED class device
names is assured thanks to the default_label and devicename properties
of newly introduced struct led_init_data.

In case none of the aforementioned properties was found, then, for OF
nodes, the node name is adopted for LED class device name.

At the occassion of amending the Documentation/leds/leds-class.txt
unify spelling: colour -> color.

Alongside these changes added is a new tool - tools/leds/get_led_device_info.sh.
The tool allows retrieving details of a LED class device's parent device,
which proves that using vendor or product name for devicename part
of LED name doesn't convey any added value since that information had been
already available in sysfs. The script performs also basic validation
of a LED class device name.

Signed-off-by: Jacek Anaszewski <jacek.anaszewski@gmail.com>
Cc: Baolin Wang <baolin.wang@linaro.org>
Cc: Dan Murphy <dmurphy@ti.com>
Cc: Daniel Mack <daniel@zonque.org>
Cc: Linus Walleij <linus.walleij@linaro.org>
Cc: Oleh Kravchenko <oleg@kaa.org.ua>
Cc: Sakari Ailus <sakari.ailus@linux.intel.com>
Cc: Simon Shields <simon@lineageos.org>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Acked-by: Pavel Machek <pavel@ucw.cz>

1 files changed, 45 insertions, 0 deletions

diff --git a/include/linux/leds.h b/include/linux/leds.h
index 2bbe8a38fe39..d101fd13e18e 100644
--- a/include/linux/leds.h
+++ b/include/linux/leds.h
@@ -8,6 +8,7 @@
 #ifndef __LINUX_LEDS_H_INCLUDED
 #define __LINUX_LEDS_H_INCLUDED
 
+#include <dt-bindings/leds/common.h>
 #include <linux/device.h>
 #include <linux/kernfs.h>
 #include <linux/list.h>
@@ -33,6 +34,25 @@ enum led_brightness {
 struct led_init_data {
 	/* device fwnode handle */
 	struct fwnode_handle *fwnode;
+	/*
+	 * default <color:function> tuple, for backward compatibility
+	 * with in-driver hard-coded LED names used as a fallback when
+	 * DT "label" property is absent; it should be set to NULL
+	 * in new LED class drivers.
+	 */
+	const char *default_label;
+	/*
+	 * string to be used for devicename section of LED class device
+	 * either for label based LED name composition path or for fwnode
+	 * based when devname_mandatory is true
+	 */
+	const char *devicename;
+	/*
+	 * indicates if LED name should always comprise devicename section;
+	 * only LEDs exposed by drivers of hot-pluggable devices should
+	 * set it to true
+	 */
+	bool devname_mandatory;
 };
 
 struct led_classdev {
@@ -258,6 +278,22 @@ extern void led_sysfs_disable(struct led_classdev *led_cdev);
 extern void led_sysfs_enable(struct led_classdev *led_cdev);
 
 /**
+ * led_compose_name - compose LED class device name
+ * @dev: LED controller device object
+ * @child: child fwnode_handle describing a LED or a group of synchronized LEDs;
+ *	   it must be provided only for fwnode based LEDs
+ * @led_classdev_name: composed LED class device name
+ *
+ * Create LED class device name basing on the provided init_data argument.
+ * The name can have <devicename:color:function> or <color:function>.
+ * form, depending on the init_data configuration.
+ *
+ * Returns: 0 on success or negative error value on failure
+ */
+extern int led_compose_name(struct device *dev, struct led_init_data *init_data,
+			    char *led_classdev_name);
+
+/**
  * led_sysfs_is_disabled - check if LED sysfs interface is disabled
  * @led_cdev: the LED to query
  *
@@ -434,6 +470,15 @@ struct led_platform_data {
 	struct led_info	*leds;
 };
 
+struct led_properties {
+	u32		color;
+	bool		color_present;
+	const char	*function;
+	u32		func_enum;
+	bool		func_enum_present;
+	const char	*label;
+};
+
 struct gpio_desc;
 typedef int (*gpio_blink_set_t)(struct gpio_desc *desc, int state,
 				unsigned long *delay_on,