// SPDX-License-Identifier: GPL-2.0+
/*
 * Fixed MDIO bus (MDIO bus emulation with fixed PHYs)
 *
 * Author: Vitaly Bordug <vbordug@ru.mvista.com>
 *         Anton Vorontsov <avorontsov@ru.mvista.com>
 *
 * Copyright (c) 2006-2007 MontaVista Software, Inc.
 */

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/mii.h>
#include <linux/phy.h>
#include <linux/phy_fixed.h>
#include <linux/err.h>
#include <linux/slab.h>
#include <linux/of.h>
#include <linux/netdevice.h>

#include "swphy.h"

/* The DSA loop driver may allocate 4 fixed PHY's, and 4 additional
 * fixed PHY's for a system should be sufficient.
 */
#define NUM_FP  8

struct fixed_phy {
        struct phy_device *phydev;
        struct fixed_phy_status status;
        int (*link_update)(struct net_device *, struct fixed_phy_status *);
};

static DECLARE_BITMAP(fixed_phy_ids, NUM_FP);
static struct fixed_phy fmb_fixed_phys[NUM_FP];
static struct mii_bus *fmb_mii_bus;

static struct fixed_phy *fixed_phy_find(int addr)
{
        return test_bit(addr, fixed_phy_ids) ? fmb_fixed_phys + addr : NULL;
}

int fixed_phy_change_carrier(struct net_device *dev, bool new_carrier)
{
        struct phy_device *phydev = dev->phydev;
        struct fixed_phy *fp;

        if (!phydev || !phydev->mdio.bus)
                return -EINVAL;

        fp = fixed_phy_find(phydev->mdio.addr);
        if (!fp)
                return -EINVAL;

        fp->status.link = new_carrier;

        return 0;
}
EXPORT_SYMBOL_GPL(fixed_phy_change_carrier);

static int fixed_mdio_read(struct mii_bus *bus, int phy_addr, int reg_num)
{
        struct fixed_phy *fp;

        fp = fixed_phy_find(phy_addr);
        if (!fp)
                return 0xffff;

        if (fp->link_update)
                fp->link_update(fp->phydev->attached_dev, &fp->status);

        return swphy_read_reg(reg_num, &fp->status);
}

static int fixed_mdio_write(struct mii_bus *bus, int phy_addr, int reg_num,
                            u16 val)
{
        return 0;
}

/*
 * If something weird is required to be done with link/speed,
 * network driver is able to assign a function to implement this.
 * May be useful for PHY's that need to be software-driven.
 */
int fixed_phy_set_link_update(struct phy_device *phydev,
                              int (*link_update)(struct net_device *,
                                                 struct fixed_phy_status *))
{
        struct fixed_phy *fp;

        if (!phydev || !phydev->mdio.bus)
                return -EINVAL;

        fp = fixed_phy_find(phydev->mdio.addr);
        if (!fp)
                return -ENOENT;

        fp->link_update = link_update;
        fp->phydev = phydev;

        return 0;
}
EXPORT_SYMBOL_GPL(fixed_phy_set_link_update);

static void fixed_phy_del(int phy_addr)
{
        struct fixed_phy *fp;

        fp = fixed_phy_find(phy_addr);
        if (!fp)
                return;

        memset(fp, 0, sizeof(*fp));
        clear_bit(phy_addr, fixed_phy_ids);
}

static int fixed_phy_get_free_addr(void)
{
        int addr;

        do {
                addr = find_first_zero_bit(fixed_phy_ids, NUM_FP);
                if (addr == NUM_FP)
                        return -ENOSPC;
        } while (test_and_set_bit(addr, fixed_phy_ids));

        return addr;
}

struct phy_device *fixed_phy_register(const struct fixed_phy_status *status,
                                      struct device_node *np)
{
        struct phy_device *phy;
        int phy_addr;
        int ret;

        ret = swphy_validate_state(status);
        if (ret < 0)
                return ERR_PTR(ret);

        if (!fmb_mii_bus || fmb_mii_bus->state != MDIOBUS_REGISTERED)
                return ERR_PTR(-EPROBE_DEFER);

        /* Get the next available PHY address, up to NUM_FP */
        phy_addr = fixed_phy_get_free_addr();
        if (phy_addr < 0)
                return ERR_PTR(phy_addr);

        fmb_fixed_phys[phy_addr].status = *status;
        fmb_fixed_phys[phy_addr].status.link = true;

        phy = get_phy_device(fmb_mii_bus, phy_addr, false);
        if (IS_ERR(phy)) {
                fixed_phy_del(phy_addr);
                return ERR_PTR(-EINVAL);
        }

        of_node_get(np);
        phy->mdio.dev.of_node = np;
        phy->is_pseudo_fixed_link = true;

        ret = phy_device_register(phy);
        if (ret) {
                phy_device_free(phy);
                of_node_put(np);
                fixed_phy_del(phy_addr);
                return ERR_PTR(ret);
        }

        return phy;
}
EXPORT_SYMBOL_GPL(fixed_phy_register);

struct phy_device *fixed_phy_register_100fd(void)
{
        static const struct fixed_phy_status status = {
                .speed  = SPEED_100,
                .duplex = DUPLEX_FULL,
        };

        return fixed_phy_register(&status, NULL);
}
EXPORT_SYMBOL_GPL(fixed_phy_register_100fd);

void fixed_phy_unregister(struct phy_device *phy)
{
        phy_device_remove(phy);
        of_node_put(phy->mdio.dev.of_node);
        fixed_phy_del(phy->mdio.addr);
        phy_device_free(phy);
}
EXPORT_SYMBOL_GPL(fixed_phy_unregister);

static int __init fixed_mdio_bus_init(void)
{
        int ret;

        fmb_mii_bus = mdiobus_alloc();
        if (!fmb_mii_bus)
                return -ENOMEM;

        snprintf(fmb_mii_bus->id, MII_BUS_ID_SIZE, "fixed-0");
        fmb_mii_bus->name = "Fixed MDIO Bus";
        fmb_mii_bus->read = &fixed_mdio_read;
        fmb_mii_bus->write = &fixed_mdio_write;
        fmb_mii_bus->phy_mask = ~0;

        ret = mdiobus_register(fmb_mii_bus);
        if (ret)
                goto err_mdiobus_alloc;

        return 0;

err_mdiobus_alloc:
        mdiobus_free(fmb_mii_bus);
        return ret;
}
module_init(fixed_mdio_bus_init);

static void __exit fixed_mdio_bus_exit(void)
{
        mdiobus_unregister(fmb_mii_bus);
        mdiobus_free(fmb_mii_bus);
}
module_exit(fixed_mdio_bus_exit);

MODULE_DESCRIPTION("Fixed MDIO bus (MDIO bus emulation with fixed PHYs)");
MODULE_AUTHOR("Vitaly Bordug");
MODULE_LICENSE("GPL");