--- /dev/null
+From 4765a9722e09765866e131ec31f7b9cf4c1f4854 Mon Sep 17 00:00:00 2001
+From: Daniel Golle <daniel@makrotopia.org>
+Date: Sun, 19 Mar 2023 12:57:50 +0000
+Subject: [PATCH] net: pcs: add driver for MediaTek SGMII PCS
+
+The SGMII core found in several MediaTek SoCs is identical to what can
+also be found in MediaTek's MT7531 Ethernet switch IC.
+As this has not always been clear, both drivers developed different
+implementations to deal with the PCS.
+Recently Alexander Couzens pointed out this fact which lead to the
+development of this shared driver.
+
+Add a dedicated driver, mostly by copying the code now found in the
+Ethernet driver. The now redundant code will be removed by a follow-up
+commit.
+
+Suggested-by: Alexander Couzens <lynxis@fe80.eu>
+Suggested-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
+Signed-off-by: Daniel Golle <daniel@makrotopia.org>
+Tested-by: Frank Wunderlich <frank-w@public-files.de>
+Reviewed-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
+Signed-off-by: Jakub Kicinski <kuba@kernel.org>
+---
+ MAINTAINERS | 8 +
+ drivers/net/pcs/Kconfig | 7 +
+ drivers/net/pcs/Makefile | 1 +
+ drivers/net/pcs/pcs-mtk-lynxi.c | 305 ++++++++++++++++++++++++++++++
+ include/linux/pcs/pcs-mtk-lynxi.h | 13 ++
+ 5 files changed, 334 insertions(+)
+ create mode 100644 drivers/net/pcs/pcs-mtk-lynxi.c
+ create mode 100644 include/linux/pcs/pcs-mtk-lynxi.h
+
+--- a/MAINTAINERS
++++ b/MAINTAINERS
+@@ -11790,6 +11790,14 @@ L: netdev@vger.kernel.org
+ S: Maintained
+ F: drivers/net/ethernet/mediatek/
+
++MEDIATEK ETHERNET PCS DRIVER
++M: Alexander Couzens <lynxis@fe80.eu>
++M: Daniel Golle <daniel@makrotopia.org>
++L: netdev@vger.kernel.org
++S: Maintained
++F: drivers/net/pcs/pcs-mtk-lynxi.c
++F: include/linux/pcs/pcs-mtk-lynxi.h
++
+ MEDIATEK I2C CONTROLLER DRIVER
+ M: Qii Wang <qii.wang@mediatek.com>
+ L: linux-i2c@vger.kernel.org
+--- a/drivers/net/pcs/Kconfig
++++ b/drivers/net/pcs/Kconfig
+@@ -18,4 +18,11 @@ config PCS_LYNX
+ This module provides helpers to phylink for managing the Lynx PCS
+ which is part of the Layerscape and QorIQ Ethernet SERDES.
+
++config PCS_MTK_LYNXI
++ tristate
++ select REGMAP
++ help
++ This module provides helpers to phylink for managing the LynxI PCS
++ which is part of MediaTek's SoC and Ethernet switch ICs.
++
+ endmenu
+--- a/drivers/net/pcs/Makefile
++++ b/drivers/net/pcs/Makefile
+@@ -5,3 +5,4 @@ pcs_xpcs-$(CONFIG_PCS_XPCS) := pcs-xpcs.
+
+ obj-$(CONFIG_PCS_XPCS) += pcs_xpcs.o
+ obj-$(CONFIG_PCS_LYNX) += pcs-lynx.o
++obj-$(CONFIG_PCS_MTK_LYNXI) += pcs-mtk-lynxi.o
+--- /dev/null
++++ b/drivers/net/pcs/pcs-mtk-lynxi.c
+@@ -0,0 +1,305 @@
++// SPDX-License-Identifier: GPL-2.0
++// Copyright (c) 2018-2019 MediaTek Inc.
++/* A library for MediaTek SGMII circuit
++ *
++ * Author: Sean Wang <sean.wang@mediatek.com>
++ * Author: Alexander Couzens <lynxis@fe80.eu>
++ * Author: Daniel Golle <daniel@makrotopia.org>
++ *
++ */
++
++#include <linux/mdio.h>
++#include <linux/of.h>
++#include <linux/pcs/pcs-mtk-lynxi.h>
++#include <linux/phylink.h>
++#include <linux/regmap.h>
++
++/* SGMII subsystem config registers */
++/* BMCR (low 16) BMSR (high 16) */
++#define SGMSYS_PCS_CONTROL_1 0x0
++#define SGMII_BMCR GENMASK(15, 0)
++#define SGMII_BMSR GENMASK(31, 16)
++
++#define SGMSYS_PCS_DEVICE_ID 0x4
++#define SGMII_LYNXI_DEV_ID 0x4d544950
++
++#define SGMSYS_PCS_ADVERTISE 0x8
++#define SGMII_ADVERTISE GENMASK(15, 0)
++#define SGMII_LPA GENMASK(31, 16)
++
++#define SGMSYS_PCS_SCRATCH 0x14
++#define SGMII_DEV_VERSION GENMASK(31, 16)
++
++/* Register to programmable link timer, the unit in 2 * 8ns */
++#define SGMSYS_PCS_LINK_TIMER 0x18
++#define SGMII_LINK_TIMER_MASK GENMASK(19, 0)
++#define SGMII_LINK_TIMER_VAL(ns) FIELD_PREP(SGMII_LINK_TIMER_MASK, \
++ ((ns) / 2 / 8))
++
++/* Register to control remote fault */
++#define SGMSYS_SGMII_MODE 0x20
++#define SGMII_IF_MODE_SGMII BIT(0)
++#define SGMII_SPEED_DUPLEX_AN BIT(1)
++#define SGMII_SPEED_MASK GENMASK(3, 2)
++#define SGMII_SPEED_10 FIELD_PREP(SGMII_SPEED_MASK, 0)
++#define SGMII_SPEED_100 FIELD_PREP(SGMII_SPEED_MASK, 1)
++#define SGMII_SPEED_1000 FIELD_PREP(SGMII_SPEED_MASK, 2)
++#define SGMII_DUPLEX_HALF BIT(4)
++#define SGMII_REMOTE_FAULT_DIS BIT(8)
++
++/* Register to reset SGMII design */
++#define SGMSYS_RESERVED_0 0x34
++#define SGMII_SW_RESET BIT(0)
++
++/* Register to set SGMII speed, ANA RG_ Control Signals III */
++#define SGMII_PHY_SPEED_MASK GENMASK(3, 2)
++#define SGMII_PHY_SPEED_1_25G FIELD_PREP(SGMII_PHY_SPEED_MASK, 0)
++#define SGMII_PHY_SPEED_3_125G FIELD_PREP(SGMII_PHY_SPEED_MASK, 1)
++
++/* Register to power up QPHY */
++#define SGMSYS_QPHY_PWR_STATE_CTRL 0xe8
++#define SGMII_PHYA_PWD BIT(4)
++
++/* Register to QPHY wrapper control */
++#define SGMSYS_QPHY_WRAP_CTRL 0xec
++#define SGMII_PN_SWAP_MASK GENMASK(1, 0)
++#define SGMII_PN_SWAP_TX_RX (BIT(0) | BIT(1))
++
++/* struct mtk_pcs_lynxi - This structure holds each sgmii regmap andassociated
++ * data
++ * @regmap: The register map pointing at the range used to setup
++ * SGMII modes
++ * @dev: Pointer to device owning the PCS
++ * @ana_rgc3: The offset of register ANA_RGC3 relative to regmap
++ * @interface: Currently configured interface mode
++ * @pcs: Phylink PCS structure
++ * @flags: Flags indicating hardware properties
++ */
++struct mtk_pcs_lynxi {
++ struct regmap *regmap;
++ u32 ana_rgc3;
++ phy_interface_t interface;
++ struct phylink_pcs pcs;
++ u32 flags;
++};
++
++static struct mtk_pcs_lynxi *pcs_to_mtk_pcs_lynxi(struct phylink_pcs *pcs)
++{
++ return container_of(pcs, struct mtk_pcs_lynxi, pcs);
++}
++
++static void mtk_pcs_lynxi_get_state(struct phylink_pcs *pcs,
++ struct phylink_link_state *state)
++{
++ struct mtk_pcs_lynxi *mpcs = pcs_to_mtk_pcs_lynxi(pcs);
++ unsigned int bm, adv;
++
++ /* Read the BMSR and LPA */
++ regmap_read(mpcs->regmap, SGMSYS_PCS_CONTROL_1, &bm);
++ regmap_read(mpcs->regmap, SGMSYS_PCS_ADVERTISE, &adv);
++
++ phylink_mii_c22_pcs_decode_state(state, FIELD_GET(SGMII_BMSR, bm),
++ FIELD_GET(SGMII_LPA, adv));
++}
++
++static int mtk_pcs_lynxi_config(struct phylink_pcs *pcs, unsigned int mode,
++ phy_interface_t interface,
++ const unsigned long *advertising,
++ bool permit_pause_to_mac)
++{
++ struct mtk_pcs_lynxi *mpcs = pcs_to_mtk_pcs_lynxi(pcs);
++ bool mode_changed = false, changed, use_an;
++ unsigned int rgc3, sgm_mode, bmcr;
++ int advertise, link_timer;
++
++ advertise = phylink_mii_c22_pcs_encode_advertisement(interface,
++ advertising);
++ if (advertise < 0)
++ return advertise;
++
++ /* Clearing IF_MODE_BIT0 switches the PCS to BASE-X mode, and
++ * we assume that fixes it's speed at bitrate = line rate (in
++ * other words, 1000Mbps or 2500Mbps).
++ */
++ if (interface == PHY_INTERFACE_MODE_SGMII) {
++ sgm_mode = SGMII_IF_MODE_SGMII;
++ if (phylink_autoneg_inband(mode)) {
++ sgm_mode |= SGMII_REMOTE_FAULT_DIS |
++ SGMII_SPEED_DUPLEX_AN;
++ use_an = true;
++ } else {
++ use_an = false;
++ }
++ } else if (phylink_autoneg_inband(mode)) {
++ /* 1000base-X or 2500base-X autoneg */
++ sgm_mode = SGMII_REMOTE_FAULT_DIS;
++ use_an = linkmode_test_bit(ETHTOOL_LINK_MODE_Autoneg_BIT,
++ advertising);
++ } else {
++ /* 1000base-X or 2500base-X without autoneg */
++ sgm_mode = 0;
++ use_an = false;
++ }
++
++ if (use_an)
++ bmcr = BMCR_ANENABLE;
++ else
++ bmcr = 0;
++
++ if (mpcs->interface != interface) {
++ link_timer = phylink_get_link_timer_ns(interface);
++ if (link_timer < 0)
++ return link_timer;
++
++ /* PHYA power down */
++ regmap_set_bits(mpcs->regmap, SGMSYS_QPHY_PWR_STATE_CTRL,
++ SGMII_PHYA_PWD);
++
++ /* Reset SGMII PCS state */
++ regmap_set_bits(mpcs->regmap, SGMSYS_RESERVED_0,
++ SGMII_SW_RESET);
++
++ if (mpcs->flags & MTK_SGMII_FLAG_PN_SWAP)
++ regmap_update_bits(mpcs->regmap, SGMSYS_QPHY_WRAP_CTRL,
++ SGMII_PN_SWAP_MASK,
++ SGMII_PN_SWAP_TX_RX);
++
++ if (interface == PHY_INTERFACE_MODE_2500BASEX)
++ rgc3 = SGMII_PHY_SPEED_3_125G;
++ else
++ rgc3 = SGMII_PHY_SPEED_1_25G;
++
++ /* Configure the underlying interface speed */
++ regmap_update_bits(mpcs->regmap, mpcs->ana_rgc3,
++ SGMII_PHY_SPEED_MASK, rgc3);
++
++ /* Setup the link timer */
++ regmap_write(mpcs->regmap, SGMSYS_PCS_LINK_TIMER,
++ SGMII_LINK_TIMER_VAL(link_timer));
++
++ mpcs->interface = interface;
++ mode_changed = true;
++ }
++
++ /* Update the advertisement, noting whether it has changed */
++ regmap_update_bits_check(mpcs->regmap, SGMSYS_PCS_ADVERTISE,
++ SGMII_ADVERTISE, advertise, &changed);
++
++ /* Update the sgmsys mode register */
++ regmap_update_bits(mpcs->regmap, SGMSYS_SGMII_MODE,
++ SGMII_REMOTE_FAULT_DIS | SGMII_SPEED_DUPLEX_AN |
++ SGMII_IF_MODE_SGMII, sgm_mode);
++
++ /* Update the BMCR */
++ regmap_update_bits(mpcs->regmap, SGMSYS_PCS_CONTROL_1,
++ BMCR_ANENABLE, bmcr);
++
++ /* Release PHYA power down state
++ * Only removing bit SGMII_PHYA_PWD isn't enough.
++ * There are cases when the SGMII_PHYA_PWD register contains 0x9 which
++ * prevents SGMII from working. The SGMII still shows link but no traffic
++ * can flow. Writing 0x0 to the PHYA_PWD register fix the issue. 0x0 was
++ * taken from a good working state of the SGMII interface.
++ * Unknown how much the QPHY needs but it is racy without a sleep.
++ * Tested on mt7622 & mt7986.
++ */
++ usleep_range(50, 100);
++ regmap_write(mpcs->regmap, SGMSYS_QPHY_PWR_STATE_CTRL, 0);
++
++ return changed || mode_changed;
++}
++
++static void mtk_pcs_lynxi_restart_an(struct phylink_pcs *pcs)
++{
++ struct mtk_pcs_lynxi *mpcs = pcs_to_mtk_pcs_lynxi(pcs);
++
++ regmap_set_bits(mpcs->regmap, SGMSYS_PCS_CONTROL_1, BMCR_ANRESTART);
++}
++
++static void mtk_pcs_lynxi_link_up(struct phylink_pcs *pcs, unsigned int mode,
++ phy_interface_t interface, int speed,
++ int duplex)
++{
++ struct mtk_pcs_lynxi *mpcs = pcs_to_mtk_pcs_lynxi(pcs);
++ unsigned int sgm_mode;
++
++ if (!phylink_autoneg_inband(mode)) {
++ /* Force the speed and duplex setting */
++ if (speed == SPEED_10)
++ sgm_mode = SGMII_SPEED_10;
++ else if (speed == SPEED_100)
++ sgm_mode = SGMII_SPEED_100;
++ else
++ sgm_mode = SGMII_SPEED_1000;
++
++ if (duplex != DUPLEX_FULL)
++ sgm_mode |= SGMII_DUPLEX_HALF;
++
++ regmap_update_bits(mpcs->regmap, SGMSYS_SGMII_MODE,
++ SGMII_DUPLEX_HALF | SGMII_SPEED_MASK,
++ sgm_mode);
++ }
++}
++
++static const struct phylink_pcs_ops mtk_pcs_lynxi_ops = {
++ .pcs_get_state = mtk_pcs_lynxi_get_state,
++ .pcs_config = mtk_pcs_lynxi_config,
++ .pcs_an_restart = mtk_pcs_lynxi_restart_an,
++ .pcs_link_up = mtk_pcs_lynxi_link_up,
++};
++
++struct phylink_pcs *mtk_pcs_lynxi_create(struct device *dev,
++ struct regmap *regmap, u32 ana_rgc3,
++ u32 flags)
++{
++ struct mtk_pcs_lynxi *mpcs;
++ u32 id, ver;
++ int ret;
++
++ ret = regmap_read(regmap, SGMSYS_PCS_DEVICE_ID, &id);
++ if (ret < 0)
++ return NULL;
++
++ if (id != SGMII_LYNXI_DEV_ID) {
++ dev_err(dev, "unknown PCS device id %08x\n", id);
++ return NULL;
++ }
++
++ ret = regmap_read(regmap, SGMSYS_PCS_SCRATCH, &ver);
++ if (ret < 0)
++ return NULL;
++
++ ver = FIELD_GET(SGMII_DEV_VERSION, ver);
++ if (ver != 0x1) {
++ dev_err(dev, "unknown PCS device version %04x\n", ver);
++ return NULL;
++ }
++
++ dev_dbg(dev, "MediaTek LynxI SGMII PCS (id 0x%08x, ver 0x%04x)\n", id,
++ ver);
++
++ mpcs = kzalloc(sizeof(*mpcs), GFP_KERNEL);
++ if (!mpcs)
++ return NULL;
++
++ mpcs->ana_rgc3 = ana_rgc3;
++ mpcs->regmap = regmap;
++ mpcs->flags = flags;
++ mpcs->pcs.ops = &mtk_pcs_lynxi_ops;
++ mpcs->pcs.poll = true;
++ mpcs->interface = PHY_INTERFACE_MODE_NA;
++
++ return &mpcs->pcs;
++}
++EXPORT_SYMBOL(mtk_pcs_lynxi_create);
++
++void mtk_pcs_lynxi_destroy(struct phylink_pcs *pcs)
++{
++ if (!pcs)
++ return;
++
++ kfree(pcs_to_mtk_pcs_lynxi(pcs));
++}
++EXPORT_SYMBOL(mtk_pcs_lynxi_destroy);
++
++MODULE_LICENSE("GPL");
+--- /dev/null
++++ b/include/linux/pcs/pcs-mtk-lynxi.h
+@@ -0,0 +1,13 @@
++/* SPDX-License-Identifier: GPL-2.0 */
++#ifndef __LINUX_PCS_MTK_LYNXI_H
++#define __LINUX_PCS_MTK_LYNXI_H
++
++#include <linux/phylink.h>
++#include <linux/regmap.h>
++
++#define MTK_SGMII_FLAG_PN_SWAP BIT(0)
++struct phylink_pcs *mtk_pcs_lynxi_create(struct device *dev,
++ struct regmap *regmap,
++ u32 ana_rgc3, u32 flags);
++void mtk_pcs_lynxi_destroy(struct phylink_pcs *pcs);
++#endif