drivers/net/ethernet/mellanox/mlxbf_gige/mlxbf_gige_mdio.c

// SPDX-License-Identifier: GPL-2.0-only OR BSD-3-Clause

/* MDIO support for Mellanox Gigabit Ethernet driver
 *
 * Copyright (C) 2020-2021 NVIDIA CORPORATION & AFFILIATES
 */

#include <linux/acpi.h>
#include <linux/bitfield.h>
#include <linux/delay.h>
#include <linux/device.h>
#include <linux/err.h>
#include <linux/io.h>
#include <linux/iopoll.h>
#include <linux/ioport.h>
#include <linux/irqreturn.h>
#include <linux/jiffies.h>
#include <linux/module.h>
#include <linux/mod_devicetable.h>
#include <linux/phy.h>
#include <linux/platform_device.h>
#include <linux/property.h>

#include "mlxbf_gige.h"

#define MLXBF_GIGE_MDIO_GW_OFFSET	0x0
#define MLXBF_GIGE_MDIO_CFG_OFFSET	0x4

/* Support clause 22 */
#define MLXBF_GIGE_MDIO_CL22_ST1	0x1
#define MLXBF_GIGE_MDIO_CL22_WRITE	0x1
#define MLXBF_GIGE_MDIO_CL22_READ	0x2

/* Busy bit is set by software and cleared by hardware */
#define MLXBF_GIGE_MDIO_SET_BUSY	0x1

/* MDIO GW register bits */
#define MLXBF_GIGE_MDIO_GW_AD_MASK	GENMASK(15, 0)
#define MLXBF_GIGE_MDIO_GW_DEVAD_MASK	GENMASK(20, 16)
#define MLXBF_GIGE_MDIO_GW_PARTAD_MASK	GENMASK(25, 21)
#define MLXBF_GIGE_MDIO_GW_OPCODE_MASK	GENMASK(27, 26)
#define MLXBF_GIGE_MDIO_GW_ST1_MASK	GENMASK(28, 28)
#define MLXBF_GIGE_MDIO_GW_BUSY_MASK	GENMASK(30, 30)

/* MDIO config register bits */
#define MLXBF_GIGE_MDIO_CFG_MDIO_MODE_MASK		GENMASK(1, 0)
#define MLXBF_GIGE_MDIO_CFG_MDIO3_3_MASK		GENMASK(2, 2)
#define MLXBF_GIGE_MDIO_CFG_MDIO_FULL_DRIVE_MASK	GENMASK(4, 4)
#define MLXBF_GIGE_MDIO_CFG_MDC_PERIOD_MASK		GENMASK(15, 8)
#define MLXBF_GIGE_MDIO_CFG_MDIO_IN_SAMP_MASK		GENMASK(23, 16)
#define MLXBF_GIGE_MDIO_CFG_MDIO_OUT_SAMP_MASK		GENMASK(31, 24)

/* Formula for encoding the MDIO period. The encoded value is
 * passed to the MDIO config register.
 *
 * mdc_clk = 2*(val + 1)*i1clk
 *
 * 400 ns = 2*(val + 1)*(((1/430)*1000) ns)
 *
 * val = (((400 * 430 / 1000) / 2) - 1)
 */
#define MLXBF_GIGE_I1CLK_MHZ		430
#define MLXBF_GIGE_MDC_CLK_NS		400

#define MLXBF_GIGE_MDIO_PERIOD	(((MLXBF_GIGE_MDC_CLK_NS * MLXBF_GIGE_I1CLK_MHZ / 1000) / 2) - 1)

#define MLXBF_GIGE_MDIO_CFG_VAL (FIELD_PREP(MLXBF_GIGE_MDIO_CFG_MDIO_MODE_MASK, 1) | \
				 FIELD_PREP(MLXBF_GIGE_MDIO_CFG_MDIO3_3_MASK, 1) | \
				 FIELD_PREP(MLXBF_GIGE_MDIO_CFG_MDIO_FULL_DRIVE_MASK, 1) | \
				 FIELD_PREP(MLXBF_GIGE_MDIO_CFG_MDC_PERIOD_MASK, \
					    MLXBF_GIGE_MDIO_PERIOD) | \
				 FIELD_PREP(MLXBF_GIGE_MDIO_CFG_MDIO_IN_SAMP_MASK, 6) | \
				 FIELD_PREP(MLXBF_GIGE_MDIO_CFG_MDIO_OUT_SAMP_MASK, 13))

static u32 mlxbf_gige_mdio_create_cmd(u16 data, int phy_add,
				      int phy_reg, u32 opcode)
{
	u32 gw_reg = 0;

	gw_reg |= FIELD_PREP(MLXBF_GIGE_MDIO_GW_AD_MASK, data);
	gw_reg |= FIELD_PREP(MLXBF_GIGE_MDIO_GW_DEVAD_MASK, phy_reg);
	gw_reg |= FIELD_PREP(MLXBF_GIGE_MDIO_GW_PARTAD_MASK, phy_add);
	gw_reg |= FIELD_PREP(MLXBF_GIGE_MDIO_GW_OPCODE_MASK, opcode);
	gw_reg |= FIELD_PREP(MLXBF_GIGE_MDIO_GW_ST1_MASK,
			     MLXBF_GIGE_MDIO_CL22_ST1);
	gw_reg |= FIELD_PREP(MLXBF_GIGE_MDIO_GW_BUSY_MASK,
			     MLXBF_GIGE_MDIO_SET_BUSY);

	return gw_reg;
}

static int mlxbf_gige_mdio_read(struct mii_bus *bus, int phy_add, int phy_reg)
{
	struct mlxbf_gige *priv = bus->priv;
	u32 cmd;
	int ret;
	u32 val;

	if (phy_reg & MII_ADDR_C45)
		return -EOPNOTSUPP;

	/* Send mdio read request */
	cmd = mlxbf_gige_mdio_create_cmd(0, phy_add, phy_reg, MLXBF_GIGE_MDIO_CL22_READ);

	writel(cmd, priv->mdio_io + MLXBF_GIGE_MDIO_GW_OFFSET);

	ret = readl_poll_timeout_atomic(priv->mdio_io + MLXBF_GIGE_MDIO_GW_OFFSET,
					val, !(val & MLXBF_GIGE_MDIO_GW_BUSY_MASK), 100, 1000000);

	if (ret) {
		writel(0, priv->mdio_io + MLXBF_GIGE_MDIO_GW_OFFSET);
		return ret;
	}

	ret = readl(priv->mdio_io + MLXBF_GIGE_MDIO_GW_OFFSET);
	/* Only return ad bits of the gw register */
	ret &= MLXBF_GIGE_MDIO_GW_AD_MASK;

	return ret;
}

static int mlxbf_gige_mdio_write(struct mii_bus *bus, int phy_add,
				 int phy_reg, u16 val)
{
	struct mlxbf_gige *priv = bus->priv;
	u32 cmd;
	int ret;
	u32 temp;

	if (phy_reg & MII_ADDR_C45)
		return -EOPNOTSUPP;

	/* Send mdio write request */
	cmd = mlxbf_gige_mdio_create_cmd(val, phy_add, phy_reg,
					 MLXBF_GIGE_MDIO_CL22_WRITE);
	writel(cmd, priv->mdio_io + MLXBF_GIGE_MDIO_GW_OFFSET);

	/* If the poll timed out, drop the request */
	ret = readl_poll_timeout_atomic(priv->mdio_io + MLXBF_GIGE_MDIO_GW_OFFSET,
					temp, !(temp & MLXBF_GIGE_MDIO_GW_BUSY_MASK), 100, 1000000);

	return ret;
}

int mlxbf_gige_mdio_probe(struct platform_device *pdev, struct mlxbf_gige *priv)
{
	struct device *dev = &pdev->dev;
	int ret;

	priv->mdio_io = devm_platform_ioremap_resource(pdev, MLXBF_GIGE_RES_MDIO9);
	if (IS_ERR(priv->mdio_io))
		return PTR_ERR(priv->mdio_io);

	/* Configure mdio parameters */
	writel(MLXBF_GIGE_MDIO_CFG_VAL,
	       priv->mdio_io + MLXBF_GIGE_MDIO_CFG_OFFSET);

	priv->mdiobus = devm_mdiobus_alloc(dev);
	if (!priv->mdiobus) {
		dev_err(dev, "Failed to alloc MDIO bus\n");
		return -ENOMEM;
	}

	priv->mdiobus->name = "mlxbf-mdio";
	priv->mdiobus->read = mlxbf_gige_mdio_read;
	priv->mdiobus->write = mlxbf_gige_mdio_write;
	priv->mdiobus->parent = dev;
	priv->mdiobus->priv = priv;
	snprintf(priv->mdiobus->id, MII_BUS_ID_SIZE, "%s",
		 dev_name(dev));

	ret = mdiobus_register(priv->mdiobus);
	if (ret)
		dev_err(dev, "Failed to register MDIO bus\n");

	return ret;
}

void mlxbf_gige_mdio_remove(struct mlxbf_gige *priv)
{
	mdiobus_unregister(priv->mdiobus);
}