mlxsw: core: Add QSFP module temperature label attribute to hwmon

Add label attribute to hwmon object for exposing QSFP module's
temperature sensor name. Modules are labeled as "front panel xxx". The
label is used by utilities such as "sensors":

front panel 001:   +0.0C  (crit =  +0.0C, emerg =  +0.0C)
..
front panel 020:  +31.0C  (crit = +70.0C, emerg = +80.0C)
..
front panel 056:  +41.0C  (crit = +70.0C, emerg = +80.0C)
Signed-off-by: Vadim Pasternak <vadimp@mellanox.com>
Reviewed-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: Ido Schimmel <idosch@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/mellanox/mlxsw/core_hwmon.c

@@ -321,6 +321,18 @@ mlxsw_hwmon_module_temp_emergency_show(struct device *dev,
 	return sprintf(buf, "%u\n", temp);
 }
 
+static ssize_t
+mlxsw_hwmon_module_temp_label_show(struct device *dev,
+				   struct device_attribute *attr,
+				   char *buf)
+{
+	struct mlxsw_hwmon_attr *mlwsw_hwmon_attr =
+			container_of(attr, struct mlxsw_hwmon_attr, dev_attr);
+
+	return sprintf(buf, "front panel %03u\n",
+		       mlwsw_hwmon_attr->type_index);
+}
+
 enum mlxsw_hwmon_attr_type {
 	MLXSW_HWMON_ATTR_TYPE_TEMP,
 	MLXSW_HWMON_ATTR_TYPE_TEMP_MAX,
@@ -332,6 +344,7 @@ enum mlxsw_hwmon_attr_type {
 	MLXSW_HWMON_ATTR_TYPE_TEMP_MODULE_FAULT,
 	MLXSW_HWMON_ATTR_TYPE_TEMP_MODULE_CRIT,
 	MLXSW_HWMON_ATTR_TYPE_TEMP_MODULE_EMERG,
+	MLXSW_HWMON_ATTR_TYPE_TEMP_MODULE_LABEL,
 };
 
 static void mlxsw_hwmon_attr_add(struct mlxsw_hwmon *mlxsw_hwmon,
@@ -408,6 +421,13 @@ static void mlxsw_hwmon_attr_add(struct mlxsw_hwmon *mlxsw_hwmon,
 		snprintf(mlxsw_hwmon_attr->name, sizeof(mlxsw_hwmon_attr->name),
 			 "temp%u_emergency", num + 1);
 		break;
+	case MLXSW_HWMON_ATTR_TYPE_TEMP_MODULE_LABEL:
+		mlxsw_hwmon_attr->dev_attr.show =
+			mlxsw_hwmon_module_temp_label_show;
+		mlxsw_hwmon_attr->dev_attr.attr.mode = 0444;
+		snprintf(mlxsw_hwmon_attr->name, sizeof(mlxsw_hwmon_attr->name),
+			 "temp%u_label", num + 1);
+		break;
 	default:
 		WARN_ON(1);
 	}
@@ -528,6 +548,9 @@ static int mlxsw_hwmon_module_init(struct mlxsw_hwmon *mlxsw_hwmon)
 		mlxsw_hwmon_attr_add(mlxsw_hwmon,
 				     MLXSW_HWMON_ATTR_TYPE_TEMP_MODULE_EMERG,
 				     index, index);
+		mlxsw_hwmon_attr_add(mlxsw_hwmon,
+				     MLXSW_HWMON_ATTR_TYPE_TEMP_MODULE_LABEL,
+				     index, index);
 		index++;
 	}