net: phy: mxl-86110: add basic support for led_brightness_set op

Add support for forcing each connected LED to be always on or always off
by implementing the led_brightness_set() op.
This is done by modifying the COM_EXT_LED_GEN_CFG register to enable
force-mode and forcing the LED either on or off.
When calling the led_hw_control_set() force-mode is again disabled for
that LED.
Implement mxl86110_modify_extended_reg() locked helper instead of
manually acquiring and releasing the MDIO bus lock for single
__mxl86110_modify_extended_reg() calls.

Signed-off-by: Daniel Golle <[e-mail]>
Reviewed-by: Andrew Lunn <[e-mail]>
Link: https://patch.msgid.link/[e-mail]
Signed-off-by: Jakub Kicinski <[e-mail]>

drivers/net/phy/mxl-86110.c

···
 
 #define MXL86110_MAX_LEDS	3
 /* LED registers and defines */
+#define MXL86110_COM_EXT_LED_GEN_CFG			0xA00B
+# define MXL86110_COM_EXT_LED_GEN_CFG_LFM(x)		((BIT(0) | BIT(1)) << (3 * (x)))
+#  define MXL86110_COM_EXT_LED_GEN_CFG_LFME(x)		(BIT(0) << (3 * (x)))
+# define MXL86110_COM_EXT_LED_GEN_CFG_LFE(x)		(BIT(2) << (3 * (x)))
+
 #define MXL86110_LED0_CFG_REG 0xA00C
 #define MXL86110_LED1_CFG_REG 0xA00D
 #define MXL86110_LED2_CFG_REG 0xA00E
···
 }
 
 /**
+ * mxl86110_modify_extended_reg() - modify bits of a PHY's extended register
+ * @phydev: pointer to the PHY device structure
+ * @regnum: register number to write
+ * @mask: bit mask of bits to clear
+ * @set: bit mask of bits to set
+ *
+ * Note: register value = (old register value & ~mask) | set.
+ *
+ * Return: 0 or negative error code
+ */
+static int mxl86110_modify_extended_reg(struct phy_device *phydev,
+					u16 regnum, u16 mask, u16 set)
+{
+	int ret;
+
+	phy_lock_mdio_bus(phydev);
+	ret = __mxl86110_modify_extended_reg(phydev, regnum, mask, set);
+	phy_unlock_mdio_bus(phydev);
+
+	return ret;
+}
+
+/**
  * mxl86110_get_wol() - report if wake-on-lan is enabled
  * @phydev: pointer to the phy_device
  * @wol: a pointer to a &struct ethtool_wolinfo
···
 				       unsigned long rules)
 {
 	u16 val = 0;
+	int ret;
 
 	if (index >= MXL86110_MAX_LEDS)
 		return -EINVAL;
···
 	    rules & BIT(TRIGGER_NETDEV_RX))
 		val |= MXL86110_LEDX_CFG_BLINK;
 
-	return mxl86110_write_extended_reg(phydev,
+	ret = mxl86110_write_extended_reg(phydev,
 					  MXL86110_LED0_CFG_REG + index, val);
+	if (ret)
+		return ret;
+
+	/* clear manual control bit */
+	ret = mxl86110_modify_extended_reg(phydev,
+					   MXL86110_COM_EXT_LED_GEN_CFG,
+					   MXL86110_COM_EXT_LED_GEN_CFG_LFE(index),
+					   0);
+
+	return ret;
+}
+
+static int mxl86110_led_brightness_set(struct phy_device *phydev,
+				       u8 index, enum led_brightness value)
+{
+	u16 mask, set;
+	int ret;
+
+	if (index >= MXL86110_MAX_LEDS)
+		return -EINVAL;
+
+	/* force manual control */
+	set = MXL86110_COM_EXT_LED_GEN_CFG_LFE(index);
+	/* clear previous force mode */
+	mask = MXL86110_COM_EXT_LED_GEN_CFG_LFM(index);
+
+	/* force LED to be permanently on */
+	if (value != LED_OFF)
+		set |= MXL86110_COM_EXT_LED_GEN_CFG_LFME(index);
+
+	ret = mxl86110_modify_extended_reg(phydev,
+					   MXL86110_COM_EXT_LED_GEN_CFG,
+					   mask, set);
+
+	return ret;
 }
 
 /**
···
 		.config_init		= mxl86110_config_init,
 		.get_wol		= mxl86110_get_wol,
 		.set_wol		= mxl86110_set_wol,
+		.led_brightness_set	= mxl86110_led_brightness_set,
 		.led_hw_is_supported	= mxl86110_led_hw_is_supported,
 		.led_hw_control_get     = mxl86110_led_hw_control_get,
 		.led_hw_control_set     = mxl86110_led_hw_control_set,