drivers/net/phy/open_alliance_helpers.c

   1 // SPDX-License-Identifier: GPL-2.0+
   2 /*
   3  * open_alliance_helpers.c - OPEN Alliance specific PHY diagnostic helpers
   4  *
   5  * This file contains helper functions for implementing advanced diagnostic
   6  * features as specified by the OPEN Alliance for automotive Ethernet PHYs.
   7  * These helpers include functionality for Time Delay Reflection (TDR), dynamic
   8  * channel quality assessment, and other PHY diagnostics.
   9  *
  10  * For more information on the specifications, refer to the OPEN Alliance
  11  * documentation: https://opensig.org/automotive-ethernet-specifications/
  12  * Currently following specifications are partially or fully implemented:
  13  * - Advanced diagnostic features for 1000BASE-T1 automotive Ethernet PHYs.
  14  *   TC12 - advanced PHY features.
  15  *   https://opensig.org/wp-content/uploads/2024/03/Advanced_PHY_features_for_automotive_Ethernet_v2.0_fin.pdf
  16  */
  17
  18 #include <linux/bitfield.h>
  19 #include <linux/ethtool_netlink.h>
  20
  21 #include "open_alliance_helpers.h"
  22
  23 /**
  24  * oa_1000bt1_get_ethtool_cable_result_code - Convert TDR status to ethtool
  25  *                                            result code
  26  * @reg_value: Value read from the TDR register
  27  *
  28  * This function takes a register value from the HDD.TDR register and converts
  29  * the TDR status to the corresponding ethtool cable test result code.
  30  *
  31  * Return: The appropriate ethtool result code based on the TDR status
  32  */
  33 int oa_1000bt1_get_ethtool_cable_result_code(u16 reg_value)
  34 {
  35         u8 tdr_status = FIELD_GET(OA_1000BT1_HDD_TDR_STATUS_MASK, reg_value);
  36         u8 dist_val = FIELD_GET(OA_1000BT1_HDD_TDR_DISTANCE_MASK, reg_value);
  37
  38         switch (tdr_status) {
  39         case OA_1000BT1_HDD_TDR_STATUS_CABLE_OK:
  40                 return ETHTOOL_A_CABLE_RESULT_CODE_OK;
  41         case OA_1000BT1_HDD_TDR_STATUS_OPEN:
  42                 return ETHTOOL_A_CABLE_RESULT_CODE_OPEN;
  43         case OA_1000BT1_HDD_TDR_STATUS_SHORT:
  44                 return ETHTOOL_A_CABLE_RESULT_CODE_SAME_SHORT;
  45         case OA_1000BT1_HDD_TDR_STATUS_NOISE:
  46                 return ETHTOOL_A_CABLE_RESULT_CODE_NOISE;
  47         default:
  48                 if (dist_val == OA_1000BT1_HDD_TDR_DISTANCE_RESOLUTION_NOT_POSSIBLE)
  49                         return ETHTOOL_A_CABLE_RESULT_CODE_RESOLUTION_NOT_POSSIBLE;
  50                 return ETHTOOL_A_CABLE_RESULT_CODE_UNSPEC;
  51         }
  52 }
  53 EXPORT_SYMBOL_GPL(oa_1000bt1_get_ethtool_cable_result_code);
  54
  55 /**
  56  * oa_1000bt1_get_tdr_distance - Get distance to the main fault from TDR
  57  *                               register value
  58  * @reg_value: Value read from the TDR register
  59  *
  60  * This function takes a register value from the HDD.TDR register and extracts
  61  * the distance to the main fault detected by the TDR feature. The distance is
  62  * measured in centimeters and ranges from 0 to 3100 centimeters. If the
  63  * distance is not available (0x3f), the function returns -ERANGE.
  64  *
  65  * Return: The distance to the main fault in centimeters, or -ERANGE if the
  66  * resolution is not possible.
  67  */
  68 int oa_1000bt1_get_tdr_distance(u16 reg_value)
  69 {
  70         u8 dist_val = FIELD_GET(OA_1000BT1_HDD_TDR_DISTANCE_MASK, reg_value);
  71
  72         if (dist_val == OA_1000BT1_HDD_TDR_DISTANCE_RESOLUTION_NOT_POSSIBLE)
  73                 return -ERANGE;
  74
  75         return dist_val * 100;
  76 }
  77 EXPORT_SYMBOL_GPL(oa_1000bt1_get_tdr_distance);