linux/drivers/net/phy/dp83td510.c

// SPDX-License-Identifier: GPL-2.0
/* Driver for the Texas Instruments DP83TD510 PHY
 * Copyright (c) 2022 Pengutronix, Oleksij Rempel <[email protected]>
 */

#include <linux/bitfield.h>
#include <linux/ethtool_netlink.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/phy.h>

#define DP83TD510E_PHY_ID

/* MDIO_MMD_VEND2 registers */
#define DP83TD510E_PHY_STS
/* Bit 7 - mii_interrupt, active high. Clears on read.
 * Note: Clearing does not necessarily deactivate IRQ pin if interrupts pending.
 * This differs from the DP83TD510E datasheet (2020) which states this bit
 * clears on write 0.
 */
#define DP83TD510E_STS_MII_INT
#define DP83TD510E_LINK_STATUS

#define DP83TD510E_GEN_CFG
#define DP83TD510E_GENCFG_INT_POLARITY
#define DP83TD510E_GENCFG_INT_EN
#define DP83TD510E_GENCFG_INT_OE

#define DP83TD510E_INTERRUPT_REG_1
#define DP83TD510E_INT1_LINK
#define DP83TD510E_INT1_LINK_EN

#define DP83TD510E_CTRL
#define DP83TD510E_CTRL_HW_RESET
#define DP83TD510E_CTRL_SW_RESET

#define DP83TD510E_AN_STAT_1
#define DP83TD510E_MASTER_SLAVE_RESOL_FAIL

#define DP83TD510E_MSE_DETECT

#define DP83TD510_SQI_MAX

/* Register values are converted to SNR(dB) as suggested by
 * "Application Report - DP83TD510E Cable Diagnostics Toolkit":
 * SNR(dB) = -10 * log10 (VAL/2^17) - 1.76 dB.
 * SQI ranges are implemented according to "OPEN ALLIANCE - Advanced diagnostic
 * features for 100BASE-T1 automotive Ethernet PHYs"
 */
static const u16 dp83td510_mse_sqi_map[] =;

/* Time Domain Reflectometry (TDR) Functionality of DP83TD510 PHY
 *
 * I assume that this PHY is using a variation of Spread Spectrum Time Domain
 * Reflectometry (SSTDR) rather than the commonly used TDR found in many PHYs.
 * Here are the following observations which likely confirm this:
 * - The DP83TD510 PHY transmits a modulated signal of configurable length
 *   (default 16000 µs) instead of a single pulse pattern, which is typical
 *   for traditional TDR.
 * - The pulse observed on the wire, triggered by the HW RESET register, is not
 *   part of the cable testing process.
 *
 * I assume that SSTDR seems to be a logical choice for the 10BaseT1L
 * environment due to improved noise resistance, making it suitable for
 * environments  with significant electrical noise, such as long 10BaseT1L cable
 * runs.
 *
 * Configuration Variables:
 * The SSTDR variation used in this PHY involves more configuration variables
 * that can dramatically affect the functionality and precision of cable
 * testing. Since most of  these configuration options are either not well
 * documented or documented with minimal details, the following sections
 * describe my understanding and observations of these variables and their
 * impact on TDR functionality.
 *
 * Timeline:
 *     ,<--cfg_pre_silence_time
 *     |            ,<-SSTDR Modulated Transmission
 *     |	    |            ,<--cfg_post_silence_time
 *     |	    |            |             ,<--Force Link Mode
 * |<--'-->|<-------'------->|<--'-->|<--------'------->|
 *
 * - cfg_pre_silence_time: Optional silence time before TDR transmission starts.
 * - SSTDR Modulated Transmission: Transmission duration configured by
 *   cfg_tdr_tx_duration and amplitude configured by cfg_tdr_tx_type.
 * - cfg_post_silence_time: Silence time after TDR transmission.
 * - Force Link Mode: If nothing is configured after cfg_post_silence_time,
 *   the PHY continues in force link mode without autonegotiation.
 */

#define DP83TD510E_TDR_CFG
#define DP83TD510E_TDR_START
#define DP83TD510E_TDR_DONE
#define DP83TD510E_TDR_FAIL

#define DP83TD510E_TDR_CFG1
/* cfg_tdr_tx_type: Transmit voltage level for TDR.
 * 0 = 1V, 1 = 2.4V
 * Note: Using different voltage levels may not work
 * in all configuration variations. For example, setting
 * 2.4V may give different cable length measurements.
 * Other settings may be needed to make it work properly.
 */
#define DP83TD510E_TDR_TX_TYPE
#define DP83TD510E_TDR_TX_TYPE_1V
#define DP83TD510E_TDR_TX_TYPE_2_4V
/* cfg_post_silence_time: Time after the TDR sequence. Since we force master mode
 * for the TDR will proceed with forced link state after this time. For Linux
 * it is better to set max value to avoid false link state detection.
 */
#define DP83TD510E_TDR_CFG1_POST_SILENCE_TIME
#define DP83TD510E_TDR_CFG1_POST_SILENCE_TIME_0MS
#define DP83TD510E_TDR_CFG1_POST_SILENCE_TIME_10MS
#define DP83TD510E_TDR_CFG1_POST_SILENCE_TIME_100MS
#define DP83TD510E_TDR_CFG1_POST_SILENCE_TIME_1000MS
/* cfg_pre_silence_time: Time before the TDR sequence. It should be enough to
 * settle down all pulses and reflections. Since for 10BASE-T1L we have
 * maximum 2000m cable length, we can set it to 1ms.
 */
#define DP83TD510E_TDR_CFG1_PRE_SILENCE_TIME
#define DP83TD510E_TDR_CFG1_PRE_SILENCE_TIME_0MS
#define DP83TD510E_TDR_CFG1_PRE_SILENCE_TIME_10MS
#define DP83TD510E_TDR_CFG1_PRE_SILENCE_TIME_100MS
#define DP83TD510E_TDR_CFG1_PRE_SILENCE_TIME_1000MS

#define DP83TD510E_TDR_CFG2
#define DP83TD510E_TDR_END_TAP_INDEX_1
#define DP83TD510E_TDR_END_TAP_INDEX_1_DEF
#define DP83TD510E_TDR_START_TAP_INDEX_1
#define DP83TD510E_TDR_START_TAP_INDEX_1_DEF

#define DP83TD510E_TDR_CFG3
/* cfg_tdr_tx_duration: Duration of the TDR transmission in microseconds.
 * This value sets the duration of the modulated signal used for TDR
 * measurements.
 * - Default: 16000 µs
 * - Observation: A minimum duration of 6000 µs is recommended to ensure
 *   accurate detection of cable faults. Durations shorter than 6000 µs may
 *   result in incomplete data, especially for shorter cables (e.g., 20 meters),
 *   leading to false "OK" results. Longer durations (e.g., 6000 µs or more)
 *   provide better accuracy, particularly for detecting open circuits.
 */
#define DP83TD510E_TDR_TX_DURATION_US
#define DP83TD510E_TDR_TX_DURATION_US_DEF

#define DP83TD510E_TDR_FAULT_CFG1
#define DP83TD510E_TDR_FLT_LOC_OFFSET_1
#define DP83TD510E_TDR_FLT_LOC_OFFSET_1_DEF
#define DP83TD510E_TDR_FLT_INIT_1
#define DP83TD510E_TDR_FLT_INIT_1_DEF

#define DP83TD510E_TDR_FAULT_STAT
#define DP83TD510E_TDR_PEAK_DETECT
#define DP83TD510E_TDR_PEAK_SIGN
#define DP83TD510E_TDR_PEAK_LOCATION

/* Not documented registers and values but recommended according to
 * "DP83TD510E Cable Diagnostics Toolkit revC"
 */
#define DP83TD510E_UNKN_030E
#define DP83TD510E_030E_VAL

static int dp83td510_config_intr(struct phy_device *phydev)
{}

static irqreturn_t dp83td510_handle_interrupt(struct phy_device *phydev)
{}

static int dp83td510_read_status(struct phy_device *phydev)
{}

static int dp83td510_config_aneg(struct phy_device *phydev)
{}

static int dp83td510_get_sqi(struct phy_device *phydev)
{}

static int dp83td510_get_sqi_max(struct phy_device *phydev)
{}

/**
 * dp83td510_cable_test_start - Start the cable test for the DP83TD510 PHY.
 * @phydev: Pointer to the phy_device structure.
 *
 * This sequence is implemented according to the "Application Note DP83TD510E
 * Cable Diagnostics Toolkit revC".
 *
 * Returns: 0 on success, a negative error code on failure.
 */
static int dp83td510_cable_test_start(struct phy_device *phydev)
{}

/**
 * dp83td510_cable_test_get_status - Get the status of the cable test for the
 *                                   DP83TD510 PHY.
 * @phydev: Pointer to the phy_device structure.
 * @finished: Pointer to a boolean that indicates whether the test is finished.
 *
 * The function sets the @finished flag to true if the test is complete.
 *
 * Returns: 0 on success or a negative error code on failure.
 */
static int dp83td510_cable_test_get_status(struct phy_device *phydev,
					   bool *finished)
{}

static int dp83td510_get_features(struct phy_device *phydev)
{}

static struct phy_driver dp83td510_driver[] =;
module_phy_driver(dp83td510_driver);

static struct mdio_device_id __maybe_unused dp83td510_tbl[] =;
MODULE_DEVICE_TABLE(mdio, dp83td510_tbl);

MODULE_DESCRIPTION();
MODULE_AUTHOR();
MODULE_LICENSE();