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 */
33int 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}
53EXPORT_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 */
68int 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}
77EXPORT_SYMBOL_GPL(oa_1000bt1_get_tdr_distance);