net: phy: Add a binding for PHY LEDs

Define common binding parsing for all PHY drivers with LEDs using
phylib. Parse the DT as part of the phy_probe and add LEDs to the
linux LED class infrastructure. For the moment, provide a dummy
brightness function, which will later be replaced with a call into the
PHY driver. This allows testing since the LED core might otherwise
reject an LED whose brightness cannot be set.

Add a dependency on LED_CLASS. It either needs to be built in, or not
enabled, since a modular build can result in linker errors.

Signed-off-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: Christian Marangi <ansuelsmth@gmail.com>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/phy/Kconfig

@@ -18,6 +18,7 @@ menuconfig PHYLIB
 	depends on NETDEVICES
 	select MDIO_DEVICE
 	select MDIO_DEVRES
+	depends on LEDS_CLASS || LEDS_CLASS=n
 	help
 	  Ethernet controllers are usually attached to PHY
 	  devices.  This option provides infrastructure for

drivers/net/phy/phy_device.c

@@ -19,10 +19,12 @@
 #include <linux/interrupt.h>
 #include <linux/io.h>
 #include <linux/kernel.h>
+#include <linux/list.h>
 #include <linux/mdio.h>
 #include <linux/mii.h>
 #include <linux/mm.h>
 #include <linux/module.h>
+#include <linux/of.h>
 #include <linux/netdevice.h>
 #include <linux/phy.h>
 #include <linux/phy_led_triggers.h>
@@ -674,6 +676,7 @@ struct phy_device *phy_device_create(struct mii_bus *bus, int addr, u32 phy_id,
 	device_initialize(&mdiodev->dev);
 
 	dev->state = PHY_DOWN;
+	INIT_LIST_HEAD(&dev->leds);
 
 	mutex_init(&dev->lock);
 	INIT_DELAYED_WORK(&dev->state_queue, phy_state_machine);
@@ -2988,6 +2991,74 @@ static bool phy_drv_supports_irq(struct phy_driver *phydrv)
 	return phydrv->config_intr && phydrv->handle_interrupt;
 }
 
+/* Dummy implementation until calls into PHY driver are added */
+static int phy_led_set_brightness(struct led_classdev *led_cdev,
+				  enum led_brightness value)
+{
+	return 0;
+}
+
+static int of_phy_led(struct phy_device *phydev,
+		      struct device_node *led)
+{
+	struct device *dev = &phydev->mdio.dev;
+	struct led_init_data init_data = {};
+	struct led_classdev *cdev;
+	struct phy_led *phyled;
+	int err;
+
+	phyled = devm_kzalloc(dev, sizeof(*phyled), GFP_KERNEL);
+	if (!phyled)
+		return -ENOMEM;
+
+	cdev = &phyled->led_cdev;
+
+	err = of_property_read_u8(led, "reg", &phyled->index);
+	if (err)
+		return err;
+
+	cdev->brightness_set_blocking = phy_led_set_brightness;
+	cdev->max_brightness = 1;
+	init_data.devicename = dev_name(&phydev->mdio.dev);
+	init_data.fwnode = of_fwnode_handle(led);
+	init_data.devname_mandatory = true;
+
+	err = devm_led_classdev_register_ext(dev, cdev, &init_data);
+	if (err)
+		return err;
+
+	list_add(&phyled->list, &phydev->leds);
+
+	return 0;
+}
+
+static int of_phy_leds(struct phy_device *phydev)
+{
+	struct device_node *node = phydev->mdio.dev.of_node;
+	struct device_node *leds, *led;
+	int err;
+
+	if (!IS_ENABLED(CONFIG_OF_MDIO))
+		return 0;
+
+	if (!node)
+		return 0;
+
+	leds = of_get_child_by_name(node, "leds");
+	if (!leds)
+		return 0;
+
+	for_each_available_child_of_node(leds, led) {
+		err = of_phy_led(phydev, led);
+		if (err) {
+			of_node_put(led);
+			return err;
+		}
+	}
+
+	return 0;
+}
+
 /**
  * fwnode_mdio_find_device - Given a fwnode, find the mdio_device
  * @fwnode: pointer to the mdio_device's fwnode
@@ -3183,6 +3254,11 @@ static int phy_probe(struct device *dev)
 	/* Set the state to READY by default */
 	phydev->state = PHY_READY;
 
+	/* Get the LEDs from the device tree, and instantiate standard
+	 * LEDs for them.
+	 */
+	err = of_phy_leds(phydev);
+
 out:
 	/* Re-assert the reset signal on error */
 	if (err)

include/linux/phy.h

@@ -14,6 +14,7 @@
 #include <linux/compiler.h>
 #include <linux/spinlock.h>
 #include <linux/ethtool.h>
+#include <linux/leds.h>
 #include <linux/linkmode.h>
 #include <linux/netlink.h>
 #include <linux/mdio.h>
@@ -600,6 +601,7 @@ struct macsec_ops;
  * @phy_num_led_triggers: Number of triggers in @phy_led_triggers
  * @led_link_trigger: LED trigger for link up/down
  * @last_triggered: last LED trigger for link speed
+ * @leds: list of PHY LED structures
  * @master_slave_set: User requested master/slave configuration
  * @master_slave_get: Current master/slave advertisement
  * @master_slave_state: Current master/slave configuration
@@ -699,6 +701,7 @@ struct phy_device {
 
 	struct phy_led_trigger *led_link_trigger;
 #endif
+	struct list_head leds;
 
 	/*
 	 * Interrupt number for this PHY
@@ -834,6 +837,19 @@ struct phy_plca_status {
 	bool pst;
 };
 
+/**
+ * struct phy_led: An LED driven by the PHY
+ *
+ * @list: List of LEDs
+ * @led_cdev: Standard LED class structure
+ * @index: Number of the LED
+ */
+struct phy_led {
+	struct list_head list;
+	struct led_classdev led_cdev;
+	u8 index;
+};
+
 /**
  * struct phy_driver - Driver structure for a particular PHY type
  *