// SPDX-License-Identifier: GPL-2.0+
/*
 * CPSW MDIO generic driver for TI AMxx/K2x/EMAC devices.
 *
 * Copyright (C) 2018 Texas Instruments Incorporated - http://www.ti.com/
 */

#include <common.h>
#include <log.h>
#include <malloc.h>
#include <asm/io.h>
#include <miiphy.h>
#include <wait_bit.h>
#include <linux/bitops.h>
#include <linux/delay.h>

struct cpsw_mdio_regs {
	u32	version;
	u32	control;
#define CONTROL_IDLE		BIT(31)
#define CONTROL_ENABLE		BIT(30)
#define CONTROL_FAULT		BIT(19)
#define CONTROL_FAULT_ENABLE	BIT(18)
#define CONTROL_DIV_MASK	GENMASK(15, 0)

	u32	alive;
	u32	link;
	u32	linkintraw;
	u32	linkintmasked;
	u32	__reserved_0[2];
	u32	userintraw;
	u32	userintmasked;
	u32	userintmaskset;
	u32	userintmaskclr;
	u32	__reserved_1[20];

	struct {
		u32		access;
		u32		physel;
#define USERACCESS_GO		BIT(31)
#define USERACCESS_WRITE	BIT(30)
#define USERACCESS_ACK		BIT(29)
#define USERACCESS_READ		(0)
#define USERACCESS_PHY_REG_SHIFT	(21)
#define USERACCESS_PHY_ADDR_SHIFT	(16)
#define USERACCESS_DATA		GENMASK(15, 0)
	} user[0];
};

#define CPSW_MDIO_DIV_DEF	0xff
#define PHY_REG_MASK		0x1f
#define PHY_ID_MASK		0x1f

/*
 * This timeout definition is a worst-case ultra defensive measure against
 * unexpected controller lock ups.  Ideally, we should never ever hit this
 * scenario in practice.
 */
#define CPSW_MDIO_TIMEOUT            100 /* msecs */

struct cpsw_mdio {
	struct cpsw_mdio_regs *regs;
	struct mii_dev *bus;
	int div;
};

/* wait until hardware is ready for another user access */
static int cpsw_mdio_wait_for_user_access(struct cpsw_mdio *mdio)
{
	return wait_for_bit_le32(&mdio->regs->user[0].access,
				 USERACCESS_GO, false,
				 CPSW_MDIO_TIMEOUT, false);
}

static int cpsw_mdio_read(struct mii_dev *bus, int phy_id,
			  int dev_addr, int phy_reg)
{
	struct cpsw_mdio *mdio = bus->priv;
	int data, ret;
	u32 reg;

	if (phy_reg & ~PHY_REG_MASK || phy_id & ~PHY_ID_MASK)
		return -EINVAL;

	ret = cpsw_mdio_wait_for_user_access(mdio);
	if (ret)
		return ret;
	reg = (USERACCESS_GO | USERACCESS_READ |
	       (phy_reg << USERACCESS_PHY_REG_SHIFT) |
	       (phy_id << USERACCESS_PHY_ADDR_SHIFT));
	writel(reg, &mdio->regs->user[0].access);
	ret = cpsw_mdio_wait_for_user_access(mdio);
	if (ret)
		return ret;

	reg = readl(&mdio->regs->user[0].access);
	data = (reg & USERACCESS_ACK) ? (reg & USERACCESS_DATA) : -1;
	return data;
}

static int cpsw_mdio_write(struct mii_dev *bus, int phy_id, int dev_addr,
			   int phy_reg, u16 data)
{
	struct cpsw_mdio *mdio = bus->priv;
	u32 reg;
	int ret;

	if (phy_reg & ~PHY_REG_MASK || phy_id & ~PHY_ID_MASK)
		return -EINVAL;

	ret = cpsw_mdio_wait_for_user_access(mdio);
	if (ret)
		return ret;
	reg = (USERACCESS_GO | USERACCESS_WRITE |
	       (phy_reg << USERACCESS_PHY_REG_SHIFT) |
	       (phy_id << USERACCESS_PHY_ADDR_SHIFT) |
	       (data & USERACCESS_DATA));
	writel(reg, &mdio->regs->user[0].access);

	return cpsw_mdio_wait_for_user_access(mdio);
}

u32 cpsw_mdio_get_alive(struct mii_dev *bus)
{
	struct cpsw_mdio *mdio = bus->priv;
	u32 val;

	val = readl(&mdio->regs->control);
	return val & GENMASK(15, 0);
}

struct mii_dev *cpsw_mdio_init(const char *name, phys_addr_t mdio_base,
			       u32 bus_freq, int fck_freq)
{
	struct cpsw_mdio *cpsw_mdio;
	int ret;

	cpsw_mdio = calloc(1, sizeof(*cpsw_mdio));
	if (!cpsw_mdio) {
		debug("failed to alloc cpsw_mdio\n");
		return NULL;
	}

	cpsw_mdio->bus = mdio_alloc();
	if (!cpsw_mdio->bus) {
		debug("failed to alloc mii bus\n");
		free(cpsw_mdio);
		return NULL;
	}

	cpsw_mdio->regs = (struct cpsw_mdio_regs *)(uintptr_t)mdio_base;

	if (!bus_freq || !fck_freq)
		cpsw_mdio->div = CPSW_MDIO_DIV_DEF;
	else
		cpsw_mdio->div = (fck_freq / bus_freq) - 1;
	cpsw_mdio->div &= CONTROL_DIV_MASK;

	/* set enable and clock divider */
	writel(cpsw_mdio->div | CONTROL_ENABLE | CONTROL_FAULT |
	       CONTROL_FAULT_ENABLE, &cpsw_mdio->regs->control);
	wait_for_bit_le32(&cpsw_mdio->regs->control,
			  CONTROL_IDLE, false, CPSW_MDIO_TIMEOUT, true);

	/*
	 * wait for scan logic to settle:
	 * the scan time consists of (a) a large fixed component, and (b) a
	 * small component that varies with the mii bus frequency.  These
	 * were estimated using measurements at 1.1 and 2.2 MHz on tnetv107x
	 * silicon.  Since the effect of (b) was found to be largely
	 * negligible, we keep things simple here.
	 */
	mdelay(1);

	cpsw_mdio->bus->read = cpsw_mdio_read;
	cpsw_mdio->bus->write = cpsw_mdio_write;
	cpsw_mdio->bus->priv = cpsw_mdio;
	snprintf(cpsw_mdio->bus->name, sizeof(cpsw_mdio->bus->name), name);

	ret = mdio_register(cpsw_mdio->bus);
	if (ret < 0) {
		debug("failed to register mii bus\n");
		goto free_bus;
	}

	return cpsw_mdio->bus;

free_bus:
	mdio_free(cpsw_mdio->bus);
	free(cpsw_mdio);
	return NULL;
}

void cpsw_mdio_free(struct mii_dev *bus)
{
	struct cpsw_mdio *mdio = bus->priv;
	u32 reg;

	/* disable mdio */
	reg = readl(&mdio->regs->control);
	reg &= ~CONTROL_ENABLE;
	writel(reg, &mdio->regs->control);

	mdio_unregister(bus);
	mdio_free(bus);
	free(mdio);
}