net: phy: sfp: Add labels to hwmon sensors

SFPs can report two different power values, the transmit power and the
receive power. Add labels to make it clear which is which. Also add
labels to the other sensors, VCC power supply, bias and module
temperature.

sensors(1) now shows:

sff2-isa-0000
Adapter: ISA adapter
VCC: +3.23 V
temperature: +33.4 C
TX_power: 276.00 uW
RX_power: 20.00 uW
bias: +0.01 A

Signed-off-by: Andrew Lunn <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

drivers/net/phy/sfp.c

···
 				return 0;
 			/* fall through */
 		case hwmon_temp_input:
+		case hwmon_temp_label:
 			return 0444;
 		default:
 			return 0;
···
 				return 0;
 			/* fall through */
 		case hwmon_in_input:
+		case hwmon_in_label:
 			return 0444;
 		default:
 			return 0;
···
 				return 0;
 			/* fall through */
 		case hwmon_curr_input:
+		case hwmon_curr_label:
 			return 0444;
 		default:
 			return 0;
···
 				return 0;
 			/* fall through */
 		case hwmon_power_input:
+		case hwmon_power_label:
 			return 0444;
 		default:
 			return 0;
···
 	}
 }
 
+static const char *const sfp_hwmon_power_labels[] = {
+	"TX_power",
+	"RX_power",
+};
+
+static int sfp_hwmon_read_string(struct device *dev,
+				 enum hwmon_sensor_types type,
+				 u32 attr, int channel, const char **str)
+{
+	switch (type) {
+	case hwmon_curr:
+		switch (attr) {
+		case hwmon_curr_label:
+			*str = "bias";
+			return 0;
+		default:
+			return -EOPNOTSUPP;
+		}
+		break;
+	case hwmon_temp:
+		switch (attr) {
+		case hwmon_temp_label:
+			*str = "temperature";
+			return 0;
+		default:
+			return -EOPNOTSUPP;
+		}
+		break;
+	case hwmon_in:
+		switch (attr) {
+		case hwmon_in_label:
+			*str = "VCC";
+			return 0;
+		default:
+			return -EOPNOTSUPP;
+		}
+		break;
+	case hwmon_power:
+		switch (attr) {
+		case hwmon_power_label:
+			*str = sfp_hwmon_power_labels[channel];
+			return 0;
+		default:
+			return -EOPNOTSUPP;
+		}
+		break;
+	default:
+		return -EOPNOTSUPP;
+	}
+
+	return -EOPNOTSUPP;
+}
+
 static const struct hwmon_ops sfp_hwmon_ops = {
 	.is_visible = sfp_hwmon_is_visible,
 	.read = sfp_hwmon_read,
+	.read_string = sfp_hwmon_read_string,
 };
 
 static u32 sfp_hwmon_chip_config[] = {
···
 	HWMON_T_MAX | HWMON_T_MIN |
 	HWMON_T_MAX_ALARM | HWMON_T_MIN_ALARM |
 	HWMON_T_CRIT | HWMON_T_LCRIT |
-	HWMON_T_CRIT_ALARM | HWMON_T_LCRIT_ALARM,
+	HWMON_T_CRIT_ALARM | HWMON_T_LCRIT_ALARM |
+	HWMON_T_LABEL,
 	0,
 };
 
···
 	HWMON_I_MAX | HWMON_I_MIN |
 	HWMON_I_MAX_ALARM | HWMON_I_MIN_ALARM |
 	HWMON_I_CRIT | HWMON_I_LCRIT |
-	HWMON_I_CRIT_ALARM | HWMON_I_LCRIT_ALARM,
+	HWMON_I_CRIT_ALARM | HWMON_I_LCRIT_ALARM |
+	HWMON_I_LABEL,
 	0,
 };
 
···
 	HWMON_C_MAX | HWMON_C_MIN |
 	HWMON_C_MAX_ALARM | HWMON_C_MIN_ALARM |
 	HWMON_C_CRIT | HWMON_C_LCRIT |
-	HWMON_C_CRIT_ALARM | HWMON_C_LCRIT_ALARM,
+	HWMON_C_CRIT_ALARM | HWMON_C_LCRIT_ALARM |
+	HWMON_C_LABEL,
 	0,
 };
 
···
 	HWMON_P_MAX | HWMON_P_MIN |
 	HWMON_P_MAX_ALARM | HWMON_P_MIN_ALARM |
 	HWMON_P_CRIT | HWMON_P_LCRIT |
-	HWMON_P_CRIT_ALARM | HWMON_P_LCRIT_ALARM,
+	HWMON_P_CRIT_ALARM | HWMON_P_LCRIT_ALARM |
+	HWMON_P_LABEL,
 	/* Receive power */
 	HWMON_P_INPUT |
 	HWMON_P_MAX | HWMON_P_MIN |
 	HWMON_P_MAX_ALARM | HWMON_P_MIN_ALARM |
 	HWMON_P_CRIT | HWMON_P_LCRIT |
-	HWMON_P_CRIT_ALARM | HWMON_P_LCRIT_ALARM,
+	HWMON_P_CRIT_ALARM | HWMON_P_LCRIT_ALARM |
+	HWMON_P_LABEL,
 	0,
 };