WIP FPC-III support

[linux/fpc-iii.git] / drivers / net / phy / phy-core.c

// SPDX-License-Identifier: GPL-2.0+
/*
 * Core PHY library, taken from phy.c
 */
#include <linux/export.h>
#include <linux/phy.h>
#include <linux/of.h>

/**
 * phy_speed_to_str - Return a string representing the PHY link speed
 *
 * @speed: Speed of the link
 */
const char *phy_speed_to_str(int speed)
{
        BUILD_BUG_ON_MSG(__ETHTOOL_LINK_MODE_MASK_NBITS != 92,
                "Enum ethtool_link_mode_bit_indices and phylib are out of sync. "
                "If a speed or mode has been added please update phy_speed_to_str "
                "and the PHY settings array.\n");

        switch (speed) {
        case SPEED_10:
                return "10Mbps";
        case SPEED_100:
                return "100Mbps";
        case SPEED_1000:
                return "1Gbps";
        case SPEED_2500:
                return "2.5Gbps";
        case SPEED_5000:
                return "5Gbps";
        case SPEED_10000:
                return "10Gbps";
        case SPEED_14000:
                return "14Gbps";
        case SPEED_20000:
                return "20Gbps";
        case SPEED_25000:
                return "25Gbps";
        case SPEED_40000:
                return "40Gbps";
        case SPEED_50000:
                return "50Gbps";
        case SPEED_56000:
                return "56Gbps";
        case SPEED_100000:
                return "100Gbps";
        case SPEED_200000:
                return "200Gbps";
        case SPEED_400000:
                return "400Gbps";
        case SPEED_UNKNOWN:
                return "Unknown";
        default:
                return "Unsupported (update phy-core.c)";
        }
}
EXPORT_SYMBOL_GPL(phy_speed_to_str);

/**
 * phy_duplex_to_str - Return string describing the duplex
 *
 * @duplex: Duplex setting to describe
 */
const char *phy_duplex_to_str(unsigned int duplex)
{
        if (duplex == DUPLEX_HALF)
                return "Half";
        if (duplex == DUPLEX_FULL)
                return "Full";
        if (duplex == DUPLEX_UNKNOWN)
                return "Unknown";
        return "Unsupported (update phy-core.c)";
}
EXPORT_SYMBOL_GPL(phy_duplex_to_str);

/* A mapping of all SUPPORTED settings to speed/duplex.  This table
 * must be grouped by speed and sorted in descending match priority
 * - iow, descending speed. */

#define PHY_SETTING(s, d, b) { .speed = SPEED_ ## s, .duplex = DUPLEX_ ## d, \
                               .bit = ETHTOOL_LINK_MODE_ ## b ## _BIT}

static const struct phy_setting settings[] = {
        /* 400G */
        PHY_SETTING( 400000, FULL, 400000baseCR8_Full           ),
        PHY_SETTING( 400000, FULL, 400000baseKR8_Full           ),
        PHY_SETTING( 400000, FULL, 400000baseLR8_ER8_FR8_Full   ),
        PHY_SETTING( 400000, FULL, 400000baseDR8_Full           ),
        PHY_SETTING( 400000, FULL, 400000baseSR8_Full           ),
        PHY_SETTING( 400000, FULL, 400000baseCR4_Full           ),
        PHY_SETTING( 400000, FULL, 400000baseKR4_Full           ),
        PHY_SETTING( 400000, FULL, 400000baseLR4_ER4_FR4_Full   ),
        PHY_SETTING( 400000, FULL, 400000baseDR4_Full           ),
        PHY_SETTING( 400000, FULL, 400000baseSR4_Full           ),
        /* 200G */
        PHY_SETTING( 200000, FULL, 200000baseCR4_Full           ),
        PHY_SETTING( 200000, FULL, 200000baseKR4_Full           ),
        PHY_SETTING( 200000, FULL, 200000baseLR4_ER4_FR4_Full   ),
        PHY_SETTING( 200000, FULL, 200000baseDR4_Full           ),
        PHY_SETTING( 200000, FULL, 200000baseSR4_Full           ),
        PHY_SETTING( 200000, FULL, 200000baseCR2_Full           ),
        PHY_SETTING( 200000, FULL, 200000baseKR2_Full           ),
        PHY_SETTING( 200000, FULL, 200000baseLR2_ER2_FR2_Full   ),
        PHY_SETTING( 200000, FULL, 200000baseDR2_Full           ),
        PHY_SETTING( 200000, FULL, 200000baseSR2_Full           ),
        /* 100G */
        PHY_SETTING( 100000, FULL, 100000baseCR4_Full           ),
        PHY_SETTING( 100000, FULL, 100000baseKR4_Full           ),
        PHY_SETTING( 100000, FULL, 100000baseLR4_ER4_Full       ),
        PHY_SETTING( 100000, FULL, 100000baseSR4_Full           ),
        PHY_SETTING( 100000, FULL, 100000baseCR2_Full           ),
        PHY_SETTING( 100000, FULL, 100000baseKR2_Full           ),
        PHY_SETTING( 100000, FULL, 100000baseLR2_ER2_FR2_Full   ),
        PHY_SETTING( 100000, FULL, 100000baseDR2_Full           ),
        PHY_SETTING( 100000, FULL, 100000baseSR2_Full           ),
        PHY_SETTING( 100000, FULL, 100000baseCR_Full            ),
        PHY_SETTING( 100000, FULL, 100000baseKR_Full            ),
        PHY_SETTING( 100000, FULL, 100000baseLR_ER_FR_Full      ),
        PHY_SETTING( 100000, FULL, 100000baseDR_Full            ),
        PHY_SETTING( 100000, FULL, 100000baseSR_Full            ),
        /* 56G */
        PHY_SETTING(  56000, FULL,  56000baseCR4_Full           ),
        PHY_SETTING(  56000, FULL,  56000baseKR4_Full           ),
        PHY_SETTING(  56000, FULL,  56000baseLR4_Full           ),
        PHY_SETTING(  56000, FULL,  56000baseSR4_Full           ),
        /* 50G */
        PHY_SETTING(  50000, FULL,  50000baseCR2_Full           ),
        PHY_SETTING(  50000, FULL,  50000baseKR2_Full           ),
        PHY_SETTING(  50000, FULL,  50000baseSR2_Full           ),
        PHY_SETTING(  50000, FULL,  50000baseCR_Full            ),
        PHY_SETTING(  50000, FULL,  50000baseKR_Full            ),
        PHY_SETTING(  50000, FULL,  50000baseLR_ER_FR_Full      ),
        PHY_SETTING(  50000, FULL,  50000baseDR_Full            ),
        PHY_SETTING(  50000, FULL,  50000baseSR_Full            ),
        /* 40G */
        PHY_SETTING(  40000, FULL,  40000baseCR4_Full           ),
        PHY_SETTING(  40000, FULL,  40000baseKR4_Full           ),
        PHY_SETTING(  40000, FULL,  40000baseLR4_Full           ),
        PHY_SETTING(  40000, FULL,  40000baseSR4_Full           ),
        /* 25G */
        PHY_SETTING(  25000, FULL,  25000baseCR_Full            ),
        PHY_SETTING(  25000, FULL,  25000baseKR_Full            ),
        PHY_SETTING(  25000, FULL,  25000baseSR_Full            ),
        /* 20G */
        PHY_SETTING(  20000, FULL,  20000baseKR2_Full           ),
        PHY_SETTING(  20000, FULL,  20000baseMLD2_Full          ),
        /* 10G */
        PHY_SETTING(  10000, FULL,  10000baseCR_Full            ),
        PHY_SETTING(  10000, FULL,  10000baseER_Full            ),
        PHY_SETTING(  10000, FULL,  10000baseKR_Full            ),
        PHY_SETTING(  10000, FULL,  10000baseKX4_Full           ),
        PHY_SETTING(  10000, FULL,  10000baseLR_Full            ),
        PHY_SETTING(  10000, FULL,  10000baseLRM_Full           ),
        PHY_SETTING(  10000, FULL,  10000baseR_FEC              ),
        PHY_SETTING(  10000, FULL,  10000baseSR_Full            ),
        PHY_SETTING(  10000, FULL,  10000baseT_Full             ),
        /* 5G */
        PHY_SETTING(   5000, FULL,   5000baseT_Full             ),
        /* 2.5G */
        PHY_SETTING(   2500, FULL,   2500baseT_Full             ),
        PHY_SETTING(   2500, FULL,   2500baseX_Full             ),
        /* 1G */
        PHY_SETTING(   1000, FULL,   1000baseKX_Full            ),
        PHY_SETTING(   1000, FULL,   1000baseT_Full             ),
        PHY_SETTING(   1000, HALF,   1000baseT_Half             ),
        PHY_SETTING(   1000, FULL,   1000baseT1_Full            ),
        PHY_SETTING(   1000, FULL,   1000baseX_Full             ),
        /* 100M */
        PHY_SETTING(    100, FULL,    100baseT_Full             ),
        PHY_SETTING(    100, FULL,    100baseT1_Full            ),
        PHY_SETTING(    100, HALF,    100baseT_Half             ),
        PHY_SETTING(    100, HALF,    100baseFX_Half            ),
        PHY_SETTING(    100, FULL,    100baseFX_Full            ),
        /* 10M */
        PHY_SETTING(     10, FULL,     10baseT_Full             ),
        PHY_SETTING(     10, HALF,     10baseT_Half             ),
};
#undef PHY_SETTING

/**
 * phy_lookup_setting - lookup a PHY setting
 * @speed: speed to match
 * @duplex: duplex to match
 * @mask: allowed link modes
 * @exact: an exact match is required
 *
 * Search the settings array for a setting that matches the speed and
 * duplex, and which is supported.
 *
 * If @exact is unset, either an exact match or %NULL for no match will
 * be returned.
 *
 * If @exact is set, an exact match, the fastest supported setting at
 * or below the specified speed, the slowest supported setting, or if
 * they all fail, %NULL will be returned.
 */
const struct phy_setting *
phy_lookup_setting(int speed, int duplex, const unsigned long *mask, bool exact)
{
        const struct phy_setting *p, *match = NULL, *last = NULL;
        int i;

        for (i = 0, p = settings; i < ARRAY_SIZE(settings); i++, p++) {
                if (p->bit < __ETHTOOL_LINK_MODE_MASK_NBITS &&
                    test_bit(p->bit, mask)) {
                        last = p;
                        if (p->speed == speed && p->duplex == duplex) {
                                /* Exact match for speed and duplex */
                                match = p;
                                break;
                        } else if (!exact) {
                                if (!match && p->speed <= speed)
                                        /* Candidate */
                                        match = p;

                                if (p->speed < speed)
                                        break;
                        }
                }
        }

        if (!match && !exact)
                match = last;

        return match;
}
EXPORT_SYMBOL_GPL(phy_lookup_setting);

size_t phy_speeds(unsigned int *speeds, size_t size,
                  unsigned long *mask)
{
        size_t count;
        int i;

        for (i = 0, count = 0; i < ARRAY_SIZE(settings) && count < size; i++)
                if (settings[i].bit < __ETHTOOL_LINK_MODE_MASK_NBITS &&
                    test_bit(settings[i].bit, mask) &&
                    (count == 0 || speeds[count - 1] != settings[i].speed))
                        speeds[count++] = settings[i].speed;

        return count;
}

static int __set_linkmode_max_speed(u32 max_speed, unsigned long *addr)
{
        const struct phy_setting *p;
        int i;

        for (i = 0, p = settings; i < ARRAY_SIZE(settings); i++, p++) {
                if (p->speed > max_speed)
                        linkmode_clear_bit(p->bit, addr);
                else
                        break;
        }

        return 0;
}

static int __set_phy_supported(struct phy_device *phydev, u32 max_speed)
{
        return __set_linkmode_max_speed(max_speed, phydev->supported);
}

/**
 * phy_set_max_speed - Set the maximum speed the PHY should support
 *
 * @phydev: The phy_device struct
 * @max_speed: Maximum speed
 *
 * The PHY might be more capable than the MAC. For example a Fast Ethernet
 * is connected to a 1G PHY. This function allows the MAC to indicate its
 * maximum speed, and so limit what the PHY will advertise.
 */
int phy_set_max_speed(struct phy_device *phydev, u32 max_speed)
{
        int err;

        err = __set_phy_supported(phydev, max_speed);
        if (err)
                return err;

        phy_advertise_supported(phydev);

        return 0;
}
EXPORT_SYMBOL(phy_set_max_speed);

void of_set_phy_supported(struct phy_device *phydev)
{
        struct device_node *node = phydev->mdio.dev.of_node;
        u32 max_speed;

        if (!IS_ENABLED(CONFIG_OF_MDIO))
                return;

        if (!node)
                return;

        if (!of_property_read_u32(node, "max-speed", &max_speed))
                __set_phy_supported(phydev, max_speed);
}

void of_set_phy_eee_broken(struct phy_device *phydev)
{
        struct device_node *node = phydev->mdio.dev.of_node;
        u32 broken = 0;

        if (!IS_ENABLED(CONFIG_OF_MDIO))
                return;

        if (!node)
                return;

        if (of_property_read_bool(node, "eee-broken-100tx"))
                broken |= MDIO_EEE_100TX;
        if (of_property_read_bool(node, "eee-broken-1000t"))
                broken |= MDIO_EEE_1000T;
        if (of_property_read_bool(node, "eee-broken-10gt"))
                broken |= MDIO_EEE_10GT;
        if (of_property_read_bool(node, "eee-broken-1000kx"))
                broken |= MDIO_EEE_1000KX;
        if (of_property_read_bool(node, "eee-broken-10gkx4"))
                broken |= MDIO_EEE_10GKX4;
        if (of_property_read_bool(node, "eee-broken-10gkr"))
                broken |= MDIO_EEE_10GKR;

        phydev->eee_broken_modes = broken;
}

/**
 * phy_resolve_aneg_pause - Determine pause autoneg results
 *
 * @phydev: The phy_device struct
 *
 * Once autoneg has completed the local pause settings can be
 * resolved.  Determine if pause and asymmetric pause should be used
 * by the MAC.
 */

void phy_resolve_aneg_pause(struct phy_device *phydev)
{
        if (phydev->duplex == DUPLEX_FULL) {
                phydev->pause = linkmode_test_bit(ETHTOOL_LINK_MODE_Pause_BIT,
                                                  phydev->lp_advertising);
                phydev->asym_pause = linkmode_test_bit(
                        ETHTOOL_LINK_MODE_Asym_Pause_BIT,
                        phydev->lp_advertising);
        }
}
EXPORT_SYMBOL_GPL(phy_resolve_aneg_pause);

/**
 * phy_resolve_aneg_linkmode - resolve the advertisements into PHY settings
 * @phydev: The phy_device struct
 *
 * Resolve our and the link partner advertisements into their corresponding
 * speed and duplex. If full duplex was negotiated, extract the pause mode
 * from the link partner mask.
 */
void phy_resolve_aneg_linkmode(struct phy_device *phydev)
{
        __ETHTOOL_DECLARE_LINK_MODE_MASK(common);
        int i;

        linkmode_and(common, phydev->lp_advertising, phydev->advertising);

        for (i = 0; i < ARRAY_SIZE(settings); i++)
                if (test_bit(settings[i].bit, common)) {
                        phydev->speed = settings[i].speed;
                        phydev->duplex = settings[i].duplex;
                        break;
                }

        phy_resolve_aneg_pause(phydev);
}
EXPORT_SYMBOL_GPL(phy_resolve_aneg_linkmode);

/**
 * phy_check_downshift - check whether downshift occurred
 * @phydev: The phy_device struct
 *
 * Check whether a downshift to a lower speed occurred. If this should be the
 * case warn the user.
 * Prerequisite for detecting downshift is that PHY driver implements the
 * read_status callback and sets phydev->speed to the actual link speed.
 */
void phy_check_downshift(struct phy_device *phydev)
{
        __ETHTOOL_DECLARE_LINK_MODE_MASK(common);
        int i, speed = SPEED_UNKNOWN;

        phydev->downshifted_rate = 0;

        if (phydev->autoneg == AUTONEG_DISABLE ||
            phydev->speed == SPEED_UNKNOWN)
                return;

        linkmode_and(common, phydev->lp_advertising, phydev->advertising);

        for (i = 0; i < ARRAY_SIZE(settings); i++)
                if (test_bit(settings[i].bit, common)) {
                        speed = settings[i].speed;
                        break;
                }

        if (speed == SPEED_UNKNOWN || phydev->speed >= speed)
                return;

        phydev_warn(phydev, "Downshift occurred from negotiated speed %s to actual speed %s, check cabling!\n",
                    phy_speed_to_str(speed), phy_speed_to_str(phydev->speed));

        phydev->downshifted_rate = 1;
}
EXPORT_SYMBOL_GPL(phy_check_downshift);

static int phy_resolve_min_speed(struct phy_device *phydev, bool fdx_only)
{
        __ETHTOOL_DECLARE_LINK_MODE_MASK(common);
        int i = ARRAY_SIZE(settings);

        linkmode_and(common, phydev->lp_advertising, phydev->advertising);

        while (--i >= 0) {
                if (test_bit(settings[i].bit, common)) {
                        if (fdx_only && settings[i].duplex != DUPLEX_FULL)
                                continue;
                        return settings[i].speed;
                }
        }

        return SPEED_UNKNOWN;
}

int phy_speed_down_core(struct phy_device *phydev)
{
        int min_common_speed = phy_resolve_min_speed(phydev, true);

        if (min_common_speed == SPEED_UNKNOWN)
                return -EINVAL;

        return __set_linkmode_max_speed(min_common_speed, phydev->advertising);
}

static void mmd_phy_indirect(struct mii_bus *bus, int phy_addr, int devad,
                             u16 regnum)
{
        /* Write the desired MMD Devad */
        __mdiobus_write(bus, phy_addr, MII_MMD_CTRL, devad);

        /* Write the desired MMD register address */
        __mdiobus_write(bus, phy_addr, MII_MMD_DATA, regnum);

        /* Select the Function : DATA with no post increment */
        __mdiobus_write(bus, phy_addr, MII_MMD_CTRL,
                        devad | MII_MMD_CTRL_NOINCR);
}

/**
 * __phy_read_mmd - Convenience function for reading a register
 * from an MMD on a given PHY.
 * @phydev: The phy_device struct
 * @devad: The MMD to read from (0..31)
 * @regnum: The register on the MMD to read (0..65535)
 *
 * Same rules as for __phy_read();
 */
int __phy_read_mmd(struct phy_device *phydev, int devad, u32 regnum)
{
        int val;

        if (regnum > (u16)~0 || devad > 32)
                return -EINVAL;

        if (phydev->drv && phydev->drv->read_mmd) {
                val = phydev->drv->read_mmd(phydev, devad, regnum);
        } else if (phydev->is_c45) {
                val = __mdiobus_c45_read(phydev->mdio.bus, phydev->mdio.addr,
                                         devad, regnum);
        } else {
                struct mii_bus *bus = phydev->mdio.bus;
                int phy_addr = phydev->mdio.addr;

                mmd_phy_indirect(bus, phy_addr, devad, regnum);

                /* Read the content of the MMD's selected register */
                val = __mdiobus_read(bus, phy_addr, MII_MMD_DATA);
        }
        return val;
}
EXPORT_SYMBOL(__phy_read_mmd);

/**
 * phy_read_mmd - Convenience function for reading a register
 * from an MMD on a given PHY.
 * @phydev: The phy_device struct
 * @devad: The MMD to read from
 * @regnum: The register on the MMD to read
 *
 * Same rules as for phy_read();
 */
int phy_read_mmd(struct phy_device *phydev, int devad, u32 regnum)
{
        int ret;

        phy_lock_mdio_bus(phydev);
        ret = __phy_read_mmd(phydev, devad, regnum);
        phy_unlock_mdio_bus(phydev);

        return ret;
}
EXPORT_SYMBOL(phy_read_mmd);

/**
 * __phy_write_mmd - Convenience function for writing a register
 * on an MMD on a given PHY.
 * @phydev: The phy_device struct
 * @devad: The MMD to read from
 * @regnum: The register on the MMD to read
 * @val: value to write to @regnum
 *
 * Same rules as for __phy_write();
 */
int __phy_write_mmd(struct phy_device *phydev, int devad, u32 regnum, u16 val)
{
        int ret;

        if (regnum > (u16)~0 || devad > 32)
                return -EINVAL;

        if (phydev->drv && phydev->drv->write_mmd) {
                ret = phydev->drv->write_mmd(phydev, devad, regnum, val);
        } else if (phydev->is_c45) {
                ret = __mdiobus_c45_write(phydev->mdio.bus, phydev->mdio.addr,
                                          devad, regnum, val);
        } else {
                struct mii_bus *bus = phydev->mdio.bus;
                int phy_addr = phydev->mdio.addr;

                mmd_phy_indirect(bus, phy_addr, devad, regnum);

                /* Write the data into MMD's selected register */
                __mdiobus_write(bus, phy_addr, MII_MMD_DATA, val);

                ret = 0;
        }
        return ret;
}
EXPORT_SYMBOL(__phy_write_mmd);

/**
 * phy_write_mmd - Convenience function for writing a register
 * on an MMD on a given PHY.
 * @phydev: The phy_device struct
 * @devad: The MMD to read from
 * @regnum: The register on the MMD to read
 * @val: value to write to @regnum
 *
 * Same rules as for phy_write();
 */
int phy_write_mmd(struct phy_device *phydev, int devad, u32 regnum, u16 val)
{
        int ret;

        phy_lock_mdio_bus(phydev);
        ret = __phy_write_mmd(phydev, devad, regnum, val);
        phy_unlock_mdio_bus(phydev);

        return ret;
}
EXPORT_SYMBOL(phy_write_mmd);

/**
 * phy_modify_changed - Function for modifying a PHY register
 * @phydev: the phy_device struct
 * @regnum: register number to modify
 * @mask: bit mask of bits to clear
 * @set: new value of bits set in mask to write to @regnum
 *
 * NOTE: MUST NOT be called from interrupt context,
 * because the bus read/write functions may wait for an interrupt
 * to conclude the operation.
 *
 * Returns negative errno, 0 if there was no change, and 1 in case of change
 */
int phy_modify_changed(struct phy_device *phydev, u32 regnum, u16 mask, u16 set)
{
        int ret;

        phy_lock_mdio_bus(phydev);
        ret = __phy_modify_changed(phydev, regnum, mask, set);
        phy_unlock_mdio_bus(phydev);

        return ret;
}
EXPORT_SYMBOL_GPL(phy_modify_changed);

/**
 * __phy_modify - Convenience function for modifying a PHY register
 * @phydev: the phy_device struct
 * @regnum: register number to modify
 * @mask: bit mask of bits to clear
 * @set: new value of bits set in mask to write to @regnum
 *
 * NOTE: MUST NOT be called from interrupt context,
 * because the bus read/write functions may wait for an interrupt
 * to conclude the operation.
 */
int __phy_modify(struct phy_device *phydev, u32 regnum, u16 mask, u16 set)
{
        int ret;

        ret = __phy_modify_changed(phydev, regnum, mask, set);

        return ret < 0 ? ret : 0;
}
EXPORT_SYMBOL_GPL(__phy_modify);

/**
 * phy_modify - Convenience function for modifying a given PHY register
 * @phydev: the phy_device struct
 * @regnum: register number to write
 * @mask: bit mask of bits to clear
 * @set: new value of bits set in mask to write to @regnum
 *
 * NOTE: MUST NOT be called from interrupt context,
 * because the bus read/write functions may wait for an interrupt
 * to conclude the operation.
 */
int phy_modify(struct phy_device *phydev, u32 regnum, u16 mask, u16 set)
{
        int ret;

        phy_lock_mdio_bus(phydev);
        ret = __phy_modify(phydev, regnum, mask, set);
        phy_unlock_mdio_bus(phydev);

        return ret;
}
EXPORT_SYMBOL_GPL(phy_modify);

/**
 * __phy_modify_mmd_changed - Function for modifying a register on MMD
 * @phydev: the phy_device struct
 * @devad: the MMD containing register to modify
 * @regnum: register number to modify
 * @mask: bit mask of bits to clear
 * @set: new value of bits set in mask to write to @regnum
 *
 * Unlocked helper function which allows a MMD register to be modified as
 * new register value = (old register value & ~mask) | set
 *
 * Returns negative errno, 0 if there was no change, and 1 in case of change
 */
int __phy_modify_mmd_changed(struct phy_device *phydev, int devad, u32 regnum,
                             u16 mask, u16 set)
{
        int new, ret;

        ret = __phy_read_mmd(phydev, devad, regnum);
        if (ret < 0)
                return ret;

        new = (ret & ~mask) | set;
        if (new == ret)
                return 0;

        ret = __phy_write_mmd(phydev, devad, regnum, new);

        return ret < 0 ? ret : 1;
}
EXPORT_SYMBOL_GPL(__phy_modify_mmd_changed);

/**
 * phy_modify_mmd_changed - Function for modifying a register on MMD
 * @phydev: the phy_device struct
 * @devad: the MMD containing register to modify
 * @regnum: register number to modify
 * @mask: bit mask of bits to clear
 * @set: new value of bits set in mask to write to @regnum
 *
 * NOTE: MUST NOT be called from interrupt context,
 * because the bus read/write functions may wait for an interrupt
 * to conclude the operation.
 *
 * Returns negative errno, 0 if there was no change, and 1 in case of change
 */
int phy_modify_mmd_changed(struct phy_device *phydev, int devad, u32 regnum,
                           u16 mask, u16 set)
{
        int ret;

        phy_lock_mdio_bus(phydev);
        ret = __phy_modify_mmd_changed(phydev, devad, regnum, mask, set);
        phy_unlock_mdio_bus(phydev);

        return ret;
}
EXPORT_SYMBOL_GPL(phy_modify_mmd_changed);

/**
 * __phy_modify_mmd - Convenience function for modifying a register on MMD
 * @phydev: the phy_device struct
 * @devad: the MMD containing register to modify
 * @regnum: register number to modify
 * @mask: bit mask of bits to clear
 * @set: new value of bits set in mask to write to @regnum
 *
 * NOTE: MUST NOT be called from interrupt context,
 * because the bus read/write functions may wait for an interrupt
 * to conclude the operation.
 */
int __phy_modify_mmd(struct phy_device *phydev, int devad, u32 regnum,
                     u16 mask, u16 set)
{
        int ret;

        ret = __phy_modify_mmd_changed(phydev, devad, regnum, mask, set);

        return ret < 0 ? ret : 0;
}
EXPORT_SYMBOL_GPL(__phy_modify_mmd);

/**
 * phy_modify_mmd - Convenience function for modifying a register on MMD
 * @phydev: the phy_device struct
 * @devad: the MMD containing register to modify
 * @regnum: register number to modify
 * @mask: bit mask of bits to clear
 * @set: new value of bits set in mask to write to @regnum
 *
 * NOTE: MUST NOT be called from interrupt context,
 * because the bus read/write functions may wait for an interrupt
 * to conclude the operation.
 */
int phy_modify_mmd(struct phy_device *phydev, int devad, u32 regnum,
                   u16 mask, u16 set)
{
        int ret;

        phy_lock_mdio_bus(phydev);
        ret = __phy_modify_mmd(phydev, devad, regnum, mask, set);
        phy_unlock_mdio_bus(phydev);

        return ret;
}
EXPORT_SYMBOL_GPL(phy_modify_mmd);

static int __phy_read_page(struct phy_device *phydev)
{
        if (WARN_ONCE(!phydev->drv->read_page, "read_page callback not available, PHY driver not loaded?\n"))
                return -EOPNOTSUPP;

        return phydev->drv->read_page(phydev);
}

static int __phy_write_page(struct phy_device *phydev, int page)
{
        if (WARN_ONCE(!phydev->drv->write_page, "write_page callback not available, PHY driver not loaded?\n"))
                return -EOPNOTSUPP;

        return phydev->drv->write_page(phydev, page);
}

/**
 * phy_save_page() - take the bus lock and save the current page
 * @phydev: a pointer to a &struct phy_device
 *
 * Take the MDIO bus lock, and return the current page number. On error,
 * returns a negative errno. phy_restore_page() must always be called
 * after this, irrespective of success or failure of this call.
 */
int phy_save_page(struct phy_device *phydev)
{
        phy_lock_mdio_bus(phydev);
        return __phy_read_page(phydev);
}
EXPORT_SYMBOL_GPL(phy_save_page);

/**
 * phy_select_page() - take the bus lock, save the current page, and set a page
 * @phydev: a pointer to a &struct phy_device
 * @page: desired page
 *
 * Take the MDIO bus lock to protect against concurrent access, save the
 * current PHY page, and set the current page.  On error, returns a
 * negative errno, otherwise returns the previous page number.
 * phy_restore_page() must always be called after this, irrespective
 * of success or failure of this call.
 */
int phy_select_page(struct phy_device *phydev, int page)
{
        int ret, oldpage;

        oldpage = ret = phy_save_page(phydev);
        if (ret < 0)
                return ret;

        if (oldpage != page) {
                ret = __phy_write_page(phydev, page);
                if (ret < 0)
                        return ret;
        }

        return oldpage;
}
EXPORT_SYMBOL_GPL(phy_select_page);

/**
 * phy_restore_page() - restore the page register and release the bus lock
 * @phydev: a pointer to a &struct phy_device
 * @oldpage: the old page, return value from phy_save_page() or phy_select_page()
 * @ret: operation's return code
 *
 * Release the MDIO bus lock, restoring @oldpage if it is a valid page.
 * This function propagates the earliest error code from the group of
 * operations.
 *
 * Returns:
 *   @oldpage if it was a negative value, otherwise
 *   @ret if it was a negative errno value, otherwise
 *   phy_write_page()'s negative value if it were in error, otherwise
 *   @ret.
 */
int phy_restore_page(struct phy_device *phydev, int oldpage, int ret)
{
        int r;

        if (oldpage >= 0) {
                r = __phy_write_page(phydev, oldpage);

                /* Propagate the operation return code if the page write
                 * was successful.
                 */
                if (ret >= 0 && r < 0)
                        ret = r;
        } else {
                /* Propagate the phy page selection error code */
                ret = oldpage;
        }

        phy_unlock_mdio_bus(phydev);

        return ret;
}
EXPORT_SYMBOL_GPL(phy_restore_page);

/**
 * phy_read_paged() - Convenience function for reading a paged register
 * @phydev: a pointer to a &struct phy_device
 * @page: the page for the phy
 * @regnum: register number
 *
 * Same rules as for phy_read().
 */
int phy_read_paged(struct phy_device *phydev, int page, u32 regnum)
{
        int ret = 0, oldpage;

        oldpage = phy_select_page(phydev, page);
        if (oldpage >= 0)
                ret = __phy_read(phydev, regnum);

        return phy_restore_page(phydev, oldpage, ret);
}
EXPORT_SYMBOL(phy_read_paged);

/**
 * phy_write_paged() - Convenience function for writing a paged register
 * @phydev: a pointer to a &struct phy_device
 * @page: the page for the phy
 * @regnum: register number
 * @val: value to write
 *
 * Same rules as for phy_write().
 */
int phy_write_paged(struct phy_device *phydev, int page, u32 regnum, u16 val)
{
        int ret = 0, oldpage;

        oldpage = phy_select_page(phydev, page);
        if (oldpage >= 0)
                ret = __phy_write(phydev, regnum, val);

        return phy_restore_page(phydev, oldpage, ret);
}
EXPORT_SYMBOL(phy_write_paged);

/**
 * phy_modify_paged_changed() - Function for modifying a paged register
 * @phydev: a pointer to a &struct phy_device
 * @page: the page for the phy
 * @regnum: register number
 * @mask: bit mask of bits to clear
 * @set: bit mask of bits to set
 *
 * Returns negative errno, 0 if there was no change, and 1 in case of change
 */
int phy_modify_paged_changed(struct phy_device *phydev, int page, u32 regnum,
                             u16 mask, u16 set)
{
        int ret = 0, oldpage;

        oldpage = phy_select_page(phydev, page);
        if (oldpage >= 0)
                ret = __phy_modify_changed(phydev, regnum, mask, set);

        return phy_restore_page(phydev, oldpage, ret);
}
EXPORT_SYMBOL(phy_modify_paged_changed);

/**
 * phy_modify_paged() - Convenience function for modifying a paged register
 * @phydev: a pointer to a &struct phy_device
 * @page: the page for the phy
 * @regnum: register number
 * @mask: bit mask of bits to clear
 * @set: bit mask of bits to set
 *
 * Same rules as for phy_read() and phy_write().
 */
int phy_modify_paged(struct phy_device *phydev, int page, u32 regnum,
                     u16 mask, u16 set)
{
        int ret = phy_modify_paged_changed(phydev, page, regnum, mask, set);

        return ret < 0 ? ret : 0;
}
EXPORT_SYMBOL(phy_modify_paged);