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>

3 files changed, 145 insertions, 3 deletions

diff --git a/drivers/leds/led-class.c b/drivers/leds/led-class.c
index 242122f49333..508d6477d0b8 100644
--- a/drivers/leds/led-class.c
+++ b/drivers/leds/led-class.c
@@ -254,17 +254,31 @@ int led_classdev_register_ext(struct device *parent,
 			      struct led_classdev *led_cdev,
 			      struct led_init_data *init_data)
 {
-	char name[LED_MAX_NAME_SIZE];
+	char composed_name[LED_MAX_NAME_SIZE];
+	char final_name[LED_MAX_NAME_SIZE];
+	const char *proposed_name = composed_name;
 	int ret;
 
-	ret = led_classdev_next_name(led_cdev->name, name, sizeof(name));
+	if (init_data) {
+		if (init_data->devname_mandatory && !init_data->devicename) {
+			dev_err(parent, "Mandatory device name is missing");
+			return -EINVAL;
+		}
+		ret = led_compose_name(parent, init_data, composed_name);
+		if (ret < 0)
+			return ret;
+	} else {
+		proposed_name = led_cdev->name;
+	}
+
+	ret = led_classdev_next_name(proposed_name, final_name, sizeof(final_name));
 	if (ret < 0)
 		return ret;
 
 	mutex_init(&led_cdev->led_access);
 	mutex_lock(&led_cdev->led_access);
 	led_cdev->dev = device_create_with_groups(leds_class, parent, 0,
-				led_cdev, led_cdev->groups, "%s", name);
+				led_cdev, led_cdev->groups, "%s", final_name);
 	if (IS_ERR(led_cdev->dev)) {
 		mutex_unlock(&led_cdev->led_access);
 		return PTR_ERR(led_cdev->dev);
diff --git a/drivers/leds/led-core.c b/drivers/leds/led-core.c
index 7107cd7e87cf..f0c1c403f678 100644
--- a/drivers/leds/led-core.c
+++ b/drivers/leds/led-core.c
@@ -13,8 +13,10 @@
 #include <linux/module.h>
 #include <linux/mutex.h>
 #include <linux/of.h>
+#include <linux/property.h>
 #include <linux/rwsem.h>
 #include <linux/slab.h>
+#include <uapi/linux/uleds.h>
 #include "leds.h"
 
 DECLARE_RWSEM(leds_list_lock);
@@ -23,6 +25,18 @@ EXPORT_SYMBOL_GPL(leds_list_lock);
 LIST_HEAD(leds_list);
 EXPORT_SYMBOL_GPL(leds_list);
 
+const char * const led_colors[LED_COLOR_ID_MAX] = {
+	[LED_COLOR_ID_WHITE] = "white",
+	[LED_COLOR_ID_RED] = "red",
+	[LED_COLOR_ID_GREEN] = "green",
+	[LED_COLOR_ID_BLUE] = "blue",
+	[LED_COLOR_ID_AMBER] = "amber",
+	[LED_COLOR_ID_VIOLET] = "violet",
+	[LED_COLOR_ID_YELLOW] = "yellow",
+	[LED_COLOR_ID_IR] = "ir",
+};
+EXPORT_SYMBOL_GPL(led_colors);
+
 static int __led_set_brightness(struct led_classdev *led_cdev,
 				enum led_brightness value)
 {
@@ -353,3 +367,116 @@ void led_sysfs_enable(struct led_classdev *led_cdev)
 	led_cdev->flags &= ~LED_SYSFS_DISABLE;
 }
 EXPORT_SYMBOL_GPL(led_sysfs_enable);
+
+static void led_parse_fwnode_props(struct device *dev,
+				   struct fwnode_handle *fwnode,
+				   struct led_properties *props)
+{
+	int ret;
+
+	if (!fwnode)
+		return;
+
+	if (fwnode_property_present(fwnode, "label")) {
+		ret = fwnode_property_read_string(fwnode, "label", &props->label);
+		if (ret)
+			dev_err(dev, "Error parsing 'label' property (%d)\n", ret);
+		return;
+	}
+
+	if (fwnode_property_present(fwnode, "color")) {
+		ret = fwnode_property_read_u32(fwnode, "color", &props->color);
+		if (ret)
+			dev_err(dev, "Error parsing 'color' property (%d)\n", ret);
+		else if (props->color >= LED_COLOR_ID_MAX)
+			dev_err(dev, "LED color identifier out of range\n");
+		else
+			props->color_present = true;
+	}
+
+
+	if (!fwnode_property_present(fwnode, "function"))
+		return;
+
+	ret = fwnode_property_read_string(fwnode, "function", &props->function);
+	if (ret) {
+		dev_err(dev,
+			"Error parsing 'function' property (%d)\n",
+			ret);
+	}
+
+	if (!fwnode_property_present(fwnode, "function-enumerator"))
+		return;
+
+	ret = fwnode_property_read_u32(fwnode, "function-enumerator",
+				       &props->func_enum);
+	if (ret) {
+		dev_err(dev,
+			"Error parsing 'function-enumerator' property (%d)\n",
+			ret);
+	} else {
+		props->func_enum_present = true;
+	}
+}
+
+int led_compose_name(struct device *dev, struct led_init_data *init_data,
+		     char *led_classdev_name)
+{
+	struct led_properties props = {};
+	struct fwnode_handle *fwnode = init_data->fwnode;
+	const char *devicename = init_data->devicename;
+
+	if (!led_classdev_name)
+		return -EINVAL;
+
+	led_parse_fwnode_props(dev, fwnode, &props);
+
+	if (props.label) {
+		/*
+		 * If init_data.devicename is NULL, then it indicates that
+		 * DT label should be used as-is for LED class device name.
+		 * Otherwise the label is prepended with devicename to compose
+		 * the final LED class device name.
+		 */
+		if (!devicename) {
+			strscpy(led_classdev_name, props.label,
+				LED_MAX_NAME_SIZE);
+		} else {
+			snprintf(led_classdev_name, LED_MAX_NAME_SIZE, "%s:%s",
+				 devicename, props.label);
+		}
+	} else if (props.function || props.color_present) {
+		char tmp_buf[LED_MAX_NAME_SIZE];
+
+		if (props.func_enum_present) {
+			snprintf(tmp_buf, LED_MAX_NAME_SIZE, "%s:%s-%d",
+				 props.color_present ? led_colors[props.color] : "",
+				 props.function ?: "", props.func_enum);
+		} else {
+			snprintf(tmp_buf, LED_MAX_NAME_SIZE, "%s:%s",
+				 props.color_present ? led_colors[props.color] : "",
+				 props.function ?: "");
+		}
+		if (init_data->devname_mandatory) {
+			snprintf(led_classdev_name, LED_MAX_NAME_SIZE, "%s:%s",
+				 devicename, tmp_buf);
+		} else {
+			strscpy(led_classdev_name, tmp_buf, LED_MAX_NAME_SIZE);
+
+		}
+	} else if (init_data->default_label) {
+		if (!devicename) {
+			dev_err(dev, "Legacy LED naming requires devicename segment");
+			return -EINVAL;
+		}
+		snprintf(led_classdev_name, LED_MAX_NAME_SIZE, "%s:%s",
+			 devicename, init_data->default_label);
+	} else if (is_of_node(fwnode)) {
+		strscpy(led_classdev_name, to_of_node(fwnode)->name,
+			LED_MAX_NAME_SIZE);
+	} else
+		return -EINVAL;
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(led_compose_name);
diff --git a/drivers/leds/leds.h b/drivers/leds/leds.h
index 47b229469069..0b577cece8f7 100644
--- a/drivers/leds/leds.h
+++ b/drivers/leds/leds.h
@@ -27,5 +27,6 @@ void led_set_brightness_nosleep(struct led_classdev *led_cdev,
 extern struct rw_semaphore leds_list_lock;
 extern struct list_head leds_list;
 extern struct list_head trigger_list;
+extern const char * const led_colors[LED_COLOR_ID_MAX];
 
 #endif	/* __LEDS_H_INCLUDED */