net: phy: dp83867: Add led_brightness_set support

Up to 4 LEDs can be attached to the PHY, add support for setting
brightness manually.

Signed-off-by: Alexander Stein <alexander.stein@ew.tq-group.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Link: https://lore.kernel.org/r/20230424134625.303957-1-alexander.stein@ew.tq-group.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

drivers/net/phy/dp83867.c

@@ -26,6 +26,8 @@
 #define MII_DP83867_MICR	0x12
 #define MII_DP83867_ISR		0x13
 #define DP83867_CFG2		0x14
+#define DP83867_LEDCR1		0x18
+#define DP83867_LEDCR2		0x19
 #define DP83867_CFG3		0x1e
 #define DP83867_CTRL		0x1f
 
@@ -150,6 +152,12 @@
 /* FLD_THR_CFG */
 #define DP83867_FLD_THR_CFG_ENERGY_LOST_THR_MASK	0x7
 
+#define DP83867_LED_COUNT	4
+
+/* LED_DRV bits */
+#define DP83867_LED_DRV_EN(x)	BIT((x) * 4)
+#define DP83867_LED_DRV_VAL(x)	BIT((x) * 4 + 1)
+
 enum {
 	DP83867_PORT_MIRROING_KEEP,
 	DP83867_PORT_MIRROING_EN,
@@ -969,6 +977,27 @@ static int dp83867_loopback(struct phy_device *phydev, bool enable)
 			  enable ? BMCR_LOOPBACK : 0);
 }
 
+static int
+dp83867_led_brightness_set(struct phy_device *phydev,
+			   u8 index, enum led_brightness brightness)
+{
+	u32 val;
+
+	if (index >= DP83867_LED_COUNT)
+		return -EINVAL;
+
+	/* DRV_EN==1: output is DRV_VAL */
+	val = DP83867_LED_DRV_EN(index);
+
+	if (brightness)
+		val |= DP83867_LED_DRV_VAL(index);
+
+	return phy_modify(phydev, DP83867_LEDCR2,
+			  DP83867_LED_DRV_VAL(index) |
+			  DP83867_LED_DRV_EN(index),
+			  val);
+}
+
 static struct phy_driver dp83867_driver[] = {
 	{
 		.phy_id		= DP83867_PHY_ID,
@@ -996,6 +1025,8 @@ static struct phy_driver dp83867_driver[] = {
 
 		.link_change_notify = dp83867_link_change_notify,
 		.set_loopback	= dp83867_loopback,
+
+		.led_brightness_set = dp83867_led_brightness_set,
 	},
 };
 module_phy_driver(dp83867_driver);