// SPDX-License-Identifier: GPL-2.0
#include <linux/acpi.h>
#include <linux/ctype.h>
#include <linux/debugfs.h>
#include <linux/delay.h>
#include <linux/gpio/consumer.h>
#include <linux/hwmon.h>
#include <linux/i2c.h>
#include <linux/interrupt.h>
#include <linux/jiffies.h>
#include <linux/mdio/mdio-i2c.h>
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/of.h>
#include <linux/phy.h>
#include <linux/platform_device.h>
#include <linux/rtnetlink.h>
#include <linux/slab.h>
#include <linux/workqueue.h>

#include "sfp.h"
#include "swphy.h"

enum {
        GPIO_MODDEF0,
        GPIO_LOS,
        GPIO_TX_FAULT,
        GPIO_TX_DISABLE,
        GPIO_RATE_SELECT,
        GPIO_MAX,

        SFP_F_PRESENT = BIT(GPIO_MODDEF0),
        SFP_F_LOS = BIT(GPIO_LOS),
        SFP_F_TX_FAULT = BIT(GPIO_TX_FAULT),
        SFP_F_TX_DISABLE = BIT(GPIO_TX_DISABLE),
        SFP_F_RATE_SELECT = BIT(GPIO_RATE_SELECT),

        SFP_E_INSERT = 0,
        SFP_E_REMOVE,
        SFP_E_DEV_ATTACH,
        SFP_E_DEV_DETACH,
        SFP_E_DEV_DOWN,
        SFP_E_DEV_UP,
        SFP_E_TX_FAULT,
        SFP_E_TX_CLEAR,
        SFP_E_LOS_HIGH,
        SFP_E_LOS_LOW,
        SFP_E_TIMEOUT,

        SFP_MOD_EMPTY = 0,
        SFP_MOD_ERROR,
        SFP_MOD_PROBE,
        SFP_MOD_WAITDEV,
        SFP_MOD_HPOWER,
        SFP_MOD_WAITPWR,
        SFP_MOD_PRESENT,

        SFP_DEV_DETACHED = 0,
        SFP_DEV_DOWN,
        SFP_DEV_UP,

        SFP_S_DOWN = 0,
        SFP_S_FAIL,
        SFP_S_WAIT,
        SFP_S_INIT,
        SFP_S_INIT_PHY,
        SFP_S_INIT_TX_FAULT,
        SFP_S_WAIT_LOS,
        SFP_S_LINK_UP,
        SFP_S_TX_FAULT,
        SFP_S_REINIT,
        SFP_S_TX_DISABLE,
};

static const char  * const mod_state_strings[] = {
        [SFP_MOD_EMPTY] = "empty",
        [SFP_MOD_ERROR] = "error",
        [SFP_MOD_PROBE] = "probe",
        [SFP_MOD_WAITDEV] = "waitdev",
        [SFP_MOD_HPOWER] = "hpower",
        [SFP_MOD_WAITPWR] = "waitpwr",
        [SFP_MOD_PRESENT] = "present",
};

static const char *mod_state_to_str(unsigned short mod_state)
{
        if (mod_state >= ARRAY_SIZE(mod_state_strings))
                return "Unknown module state";
        return mod_state_strings[mod_state];
}

static const char * const dev_state_strings[] = {
        [SFP_DEV_DETACHED] = "detached",
        [SFP_DEV_DOWN] = "down",
        [SFP_DEV_UP] = "up",
};

static const char *dev_state_to_str(unsigned short dev_state)
{
        if (dev_state >= ARRAY_SIZE(dev_state_strings))
                return "Unknown device state";
        return dev_state_strings[dev_state];
}

static const char * const event_strings[] = {
        [SFP_E_INSERT] = "insert",
        [SFP_E_REMOVE] = "remove",
        [SFP_E_DEV_ATTACH] = "dev_attach",
        [SFP_E_DEV_DETACH] = "dev_detach",
        [SFP_E_DEV_DOWN] = "dev_down",
        [SFP_E_DEV_UP] = "dev_up",
        [SFP_E_TX_FAULT] = "tx_fault",
        [SFP_E_TX_CLEAR] = "tx_clear",
        [SFP_E_LOS_HIGH] = "los_high",
        [SFP_E_LOS_LOW] = "los_low",
        [SFP_E_TIMEOUT] = "timeout",
};

static const char *event_to_str(unsigned short event)
{
        if (event >= ARRAY_SIZE(event_strings))
                return "Unknown event";
        return event_strings[event];
}

static const char * const sm_state_strings[] = {
        [SFP_S_DOWN] = "down",
        [SFP_S_FAIL] = "fail",
        [SFP_S_WAIT] = "wait",
        [SFP_S_INIT] = "init",
        [SFP_S_INIT_PHY] = "init_phy",
        [SFP_S_INIT_TX_FAULT] = "init_tx_fault",
        [SFP_S_WAIT_LOS] = "wait_los",
        [SFP_S_LINK_UP] = "link_up",
        [SFP_S_TX_FAULT] = "tx_fault",
        [SFP_S_REINIT] = "reinit",
        [SFP_S_TX_DISABLE] = "tx_disable",
};

static const char *sm_state_to_str(unsigned short sm_state)
{
        if (sm_state >= ARRAY_SIZE(sm_state_strings))
                return "Unknown state";
        return sm_state_strings[sm_state];
}

static const char *gpio_of_names[] = {
        "mod-def0",
        "los",
        "tx-fault",
        "tx-disable",
        "rate-select0",
};

static const enum gpiod_flags gpio_flags[] = {
        GPIOD_IN,
        GPIOD_IN,
        GPIOD_IN,
        GPIOD_ASIS,
        GPIOD_ASIS,
};

/* t_start_up (SFF-8431) or t_init (SFF-8472) is the time required for a
 * non-cooled module to initialise its laser safety circuitry. We wait
 * an initial T_WAIT period before we check the tx fault to give any PHY
 * on board (for a copper SFP) time to initialise.
 */
#define T_WAIT                  msecs_to_jiffies(50)
#define T_START_UP              msecs_to_jiffies(300)
#define T_START_UP_BAD_GPON     msecs_to_jiffies(60000)

/* t_reset is the time required to assert the TX_DISABLE signal to reset
 * an indicated TX_FAULT.
 */
#define T_RESET_US              10
#define T_FAULT_RECOVER         msecs_to_jiffies(1000)

/* N_FAULT_INIT is the number of recovery attempts at module initialisation
 * time. If the TX_FAULT signal is not deasserted after this number of
 * attempts at clearing it, we decide that the module is faulty.
 * N_FAULT is the same but after the module has initialised.
 */
#define N_FAULT_INIT            5
#define N_FAULT                 5

/* T_PHY_RETRY is the time interval between attempts to probe the PHY.
 * R_PHY_RETRY is the number of attempts.
 */
#define T_PHY_RETRY             msecs_to_jiffies(50)
#define R_PHY_RETRY             12

/* SFP module presence detection is poor: the three MOD DEF signals are
 * the same length on the PCB, which means it's possible for MOD DEF 0 to
 * connect before the I2C bus on MOD DEF 1/2.
 *
 * The SFF-8472 specifies t_serial ("Time from power on until module is
 * ready for data transmission over the two wire serial bus.") as 300ms.
 */
#define T_SERIAL                msecs_to_jiffies(300)
#define T_HPOWER_LEVEL          msecs_to_jiffies(300)
#define T_PROBE_RETRY_INIT      msecs_to_jiffies(100)
#define R_PROBE_RETRY_INIT      10
#define T_PROBE_RETRY_SLOW      msecs_to_jiffies(5000)
#define R_PROBE_RETRY_SLOW      12

/* SFP modules appear to always have their PHY configured for bus address
 * 0x56 (which with mdio-i2c, translates to a PHY address of 22).
 */
#define SFP_PHY_ADDR    22

struct sff_data {
        unsigned int gpios;
        bool (*module_supported)(const struct sfp_eeprom_id *id);
};

struct sfp {
        struct device *dev;
        struct i2c_adapter *i2c;
        struct mii_bus *i2c_mii;
        struct sfp_bus *sfp_bus;
        struct phy_device *mod_phy;
        const struct sff_data *type;
        size_t i2c_block_size;
        u32 max_power_mW;

        unsigned int (*get_state)(struct sfp *);
        void (*set_state)(struct sfp *, unsigned int);
        int (*read)(struct sfp *, bool, u8, void *, size_t);
        int (*write)(struct sfp *, bool, u8, void *, size_t);

        struct gpio_desc *gpio[GPIO_MAX];
        int gpio_irq[GPIO_MAX];

        bool need_poll;

        struct mutex st_mutex;                  /* Protects state */
        unsigned int state_soft_mask;
        unsigned int state;
        struct delayed_work poll;
        struct delayed_work timeout;
        struct mutex sm_mutex;                  /* Protects state machine */
        unsigned char sm_mod_state;
        unsigned char sm_mod_tries_init;
        unsigned char sm_mod_tries;
        unsigned char sm_dev_state;
        unsigned short sm_state;
        unsigned char sm_fault_retries;
        unsigned char sm_phy_retries;

        struct sfp_eeprom_id id;
        unsigned int module_power_mW;
        unsigned int module_t_start_up;
        bool tx_fault_ignore;

#if IS_ENABLED(CONFIG_HWMON)
        struct sfp_diag diag;
        struct delayed_work hwmon_probe;
        unsigned int hwmon_tries;
        struct device *hwmon_dev;
        char *hwmon_name;
#endif

#if IS_ENABLED(CONFIG_DEBUG_FS)
        struct dentry *debugfs_dir;
#endif
};

static bool sff_module_supported(const struct sfp_eeprom_id *id)
{
        return id->base.phys_id == SFF8024_ID_SFF_8472 &&
               id->base.phys_ext_id == SFP_PHYS_EXT_ID_SFP;
}

static const struct sff_data sff_data = {
        .gpios = SFP_F_LOS | SFP_F_TX_FAULT | SFP_F_TX_DISABLE,
        .module_supported = sff_module_supported,
};

static bool sfp_module_supported(const struct sfp_eeprom_id *id)
{
        if (id->base.phys_id == SFF8024_ID_SFP &&
            id->base.phys_ext_id == SFP_PHYS_EXT_ID_SFP)
                return true;

        /* SFP GPON module Ubiquiti U-Fiber Instant has in its EEPROM stored
         * phys id SFF instead of SFP. Therefore mark this module explicitly
         * as supported based on vendor name and pn match.
         */
        if (id->base.phys_id == SFF8024_ID_SFF_8472 &&
            id->base.phys_ext_id == SFP_PHYS_EXT_ID_SFP &&
            !memcmp(id->base.vendor_name, "UBNT            ", 16) &&
            !memcmp(id->base.vendor_pn, "UF-INSTANT      ", 16))
                return true;

        return false;
}

static const struct sff_data sfp_data = {
        .gpios = SFP_F_PRESENT | SFP_F_LOS | SFP_F_TX_FAULT |
                 SFP_F_TX_DISABLE | SFP_F_RATE_SELECT,
        .module_supported = sfp_module_supported,
};

static const struct of_device_id sfp_of_match[] = {
        { .compatible = "sff,sff", .data = &sff_data, },
        { .compatible = "sff,sfp", .data = &sfp_data, },
        { },
};
MODULE_DEVICE_TABLE(of, sfp_of_match);

static unsigned long poll_jiffies;

static unsigned int sfp_gpio_get_state(struct sfp *sfp)
{
        unsigned int i, state, v;

        for (i = state = 0; i < GPIO_MAX; i++) {
                if (gpio_flags[i] != GPIOD_IN || !sfp->gpio[i])
                        continue;

                v = gpiod_get_value_cansleep(sfp->gpio[i]);
                if (v)
                        state |= BIT(i);
        }

        return state;
}

static unsigned int sff_gpio_get_state(struct sfp *sfp)
{
        return sfp_gpio_get_state(sfp) | SFP_F_PRESENT;
}

static void sfp_gpio_set_state(struct sfp *sfp, unsigned int state)
{
        if (state & SFP_F_PRESENT) {
                /* If the module is present, drive the signals */
                if (sfp->gpio[GPIO_TX_DISABLE])
                        gpiod_direction_output(sfp->gpio[GPIO_TX_DISABLE],
                                               state & SFP_F_TX_DISABLE);
                if (state & SFP_F_RATE_SELECT)
                        gpiod_direction_output(sfp->gpio[GPIO_RATE_SELECT],
                                               state & SFP_F_RATE_SELECT);
        } else {
                /* Otherwise, let them float to the pull-ups */
                if (sfp->gpio[GPIO_TX_DISABLE])
                        gpiod_direction_input(sfp->gpio[GPIO_TX_DISABLE]);
                if (state & SFP_F_RATE_SELECT)
                        gpiod_direction_input(sfp->gpio[GPIO_RATE_SELECT]);
        }
}

static int sfp_i2c_read(struct sfp *sfp, bool a2, u8 dev_addr, void *buf,
                        size_t len)
{
        struct i2c_msg msgs[2];
        u8 bus_addr = a2 ? 0x51 : 0x50;
        size_t block_size = sfp->i2c_block_size;
        size_t this_len;
        int ret;

        msgs[0].addr = bus_addr;
        msgs[0].flags = 0;
        msgs[0].len = 1;
        msgs[0].buf = &dev_addr;
        msgs[1].addr = bus_addr;
        msgs[1].flags = I2C_M_RD;
        msgs[1].len = len;
        msgs[1].buf = buf;

        while (len) {
                this_len = len;
                if (this_len > block_size)
                        this_len = block_size;

                msgs[1].len = this_len;

                ret = i2c_transfer(sfp->i2c, msgs, ARRAY_SIZE(msgs));
                if (ret < 0)
                        return ret;

                if (ret != ARRAY_SIZE(msgs))
                        break;

                msgs[1].buf += this_len;
                dev_addr += this_len;
                len -= this_len;
        }

        return msgs[1].buf - (u8 *)buf;
}

static int sfp_i2c_write(struct sfp *sfp, bool a2, u8 dev_addr, void *buf,
        size_t len)
{
        struct i2c_msg msgs[1];
        u8 bus_addr = a2 ? 0x51 : 0x50;
        int ret;

        msgs[0].addr = bus_addr;
        msgs[0].flags = 0;
        msgs[0].len = 1 + len;
        msgs[0].buf = kmalloc(1 + len, GFP_KERNEL);
        if (!msgs[0].buf)
                return -ENOMEM;

        msgs[0].buf[0] = dev_addr;
        memcpy(&msgs[0].buf[1], buf, len);

        ret = i2c_transfer(sfp->i2c, msgs, ARRAY_SIZE(msgs));

        kfree(msgs[0].buf);

        if (ret < 0)
                return ret;

        return ret == ARRAY_SIZE(msgs) ? len : 0;
}

static int sfp_i2c_configure(struct sfp *sfp, struct i2c_adapter *i2c)
{
        struct mii_bus *i2c_mii;
        int ret;

        if (!i2c_check_functionality(i2c, I2C_FUNC_I2C))
                return -EINVAL;

        sfp->i2c = i2c;
        sfp->read = sfp_i2c_read;
        sfp->write = sfp_i2c_write;

        i2c_mii = mdio_i2c_alloc(sfp->dev, i2c);
        if (IS_ERR(i2c_mii))
                return PTR_ERR(i2c_mii);

        i2c_mii->name = "SFP I2C Bus";
        i2c_mii->phy_mask = ~0;

        ret = mdiobus_register(i2c_mii);
        if (ret < 0) {
                mdiobus_free(i2c_mii);
                return ret;
        }

        sfp->i2c_mii = i2c_mii;

        return 0;
}

/* Interface */
static int sfp_read(struct sfp *sfp, bool a2, u8 addr, void *buf, size_t len)
{
        return sfp->read(sfp, a2, addr, buf, len);
}

static int sfp_write(struct sfp *sfp, bool a2, u8 addr, void *buf, size_t len)
{
        return sfp->write(sfp, a2, addr, buf, len);
}

static unsigned int sfp_soft_get_state(struct sfp *sfp)
{
        unsigned int state = 0;
        u8 status;
        int ret;

        ret = sfp_read(sfp, true, SFP_STATUS, &status, sizeof(status));
        if (ret == sizeof(status)) {
                if (status & SFP_STATUS_RX_LOS)
                        state |= SFP_F_LOS;
                if (status & SFP_STATUS_TX_FAULT)
                        state |= SFP_F_TX_FAULT;
        } else {
                dev_err_ratelimited(sfp->dev,
                                    "failed to read SFP soft status: %pe\n",
                                    ERR_PTR(ret));
                /* Preserve the current state */
                state = sfp->state;
        }

        return state & sfp->state_soft_mask;
}

static void sfp_soft_set_state(struct sfp *sfp, unsigned int state)
{
        u8 status;

        if (sfp_read(sfp, true, SFP_STATUS, &status, sizeof(status)) ==
                     sizeof(status)) {
                if (state & SFP_F_TX_DISABLE)
                        status |= SFP_STATUS_TX_DISABLE_FORCE;
                else
                        status &= ~SFP_STATUS_TX_DISABLE_FORCE;

                sfp_write(sfp, true, SFP_STATUS, &status, sizeof(status));
        }
}

static void sfp_soft_start_poll(struct sfp *sfp)
{
        const struct sfp_eeprom_id *id = &sfp->id;

        sfp->state_soft_mask = 0;
        if (id->ext.enhopts & SFP_ENHOPTS_SOFT_TX_DISABLE &&
            !sfp->gpio[GPIO_TX_DISABLE])
                sfp->state_soft_mask |= SFP_F_TX_DISABLE;
        if (id->ext.enhopts & SFP_ENHOPTS_SOFT_TX_FAULT &&
            !sfp->gpio[GPIO_TX_FAULT])
                sfp->state_soft_mask |= SFP_F_TX_FAULT;
        if (id->ext.enhopts & SFP_ENHOPTS_SOFT_RX_LOS &&
            !sfp->gpio[GPIO_LOS])
                sfp->state_soft_mask |= SFP_F_LOS;

        if (sfp->state_soft_mask & (SFP_F_LOS | SFP_F_TX_FAULT) &&
            !sfp->need_poll)
                mod_delayed_work(system_wq, &sfp->poll, poll_jiffies);
}

static void sfp_soft_stop_poll(struct sfp *sfp)
{
        sfp->state_soft_mask = 0;
}

static unsigned int sfp_get_state(struct sfp *sfp)
{
        unsigned int state = sfp->get_state(sfp);

        if (state & SFP_F_PRESENT &&
            sfp->state_soft_mask & (SFP_F_LOS | SFP_F_TX_FAULT))
                state |= sfp_soft_get_state(sfp);

        return state;
}

static void sfp_set_state(struct sfp *sfp, unsigned int state)
{
        sfp->set_state(sfp, state);

        if (state & SFP_F_PRESENT &&
            sfp->state_soft_mask & SFP_F_TX_DISABLE)
                sfp_soft_set_state(sfp, state);
}

static unsigned int sfp_check(void *buf, size_t len)
{
        u8 *p, check;

        for (p = buf, check = 0; len; p++, len--)
                check += *p;

        return check;
}

/* hwmon */
#if IS_ENABLED(CONFIG_HWMON)
static umode_t sfp_hwmon_is_visible(const void *data,
                                    enum hwmon_sensor_types type,
                                    u32 attr, int channel)
{
        const struct sfp *sfp = data;

        switch (type) {
        case hwmon_temp:
                switch (attr) {
                case hwmon_temp_min_alarm:
                case hwmon_temp_max_alarm:
                case hwmon_temp_lcrit_alarm:
                case hwmon_temp_crit_alarm:
                case hwmon_temp_min:
                case hwmon_temp_max:
                case hwmon_temp_lcrit:
                case hwmon_temp_crit:
                        if (!(sfp->id.ext.enhopts & SFP_ENHOPTS_ALARMWARN))
                                return 0;
                        fallthrough;
                case hwmon_temp_input:
                case hwmon_temp_label:
                        return 0444;
                default:
                        return 0;
                }
        case hwmon_in:
                switch (attr) {
                case hwmon_in_min_alarm:
                case hwmon_in_max_alarm:
                case hwmon_in_lcrit_alarm:
                case hwmon_in_crit_alarm:
                case hwmon_in_min:
                case hwmon_in_max:
                case hwmon_in_lcrit:
                case hwmon_in_crit:
                        if (!(sfp->id.ext.enhopts & SFP_ENHOPTS_ALARMWARN))
                                return 0;
                        fallthrough;
                case hwmon_in_input:
                case hwmon_in_label:
                        return 0444;
                default:
                        return 0;
                }
        case hwmon_curr:
                switch (attr) {
                case hwmon_curr_min_alarm:
                case hwmon_curr_max_alarm:
                case hwmon_curr_lcrit_alarm:
                case hwmon_curr_crit_alarm:
                case hwmon_curr_min:
                case hwmon_curr_max:
                case hwmon_curr_lcrit:
                case hwmon_curr_crit:
                        if (!(sfp->id.ext.enhopts & SFP_ENHOPTS_ALARMWARN))
                                return 0;
                        fallthrough;
                case hwmon_curr_input:
                case hwmon_curr_label:
                        return 0444;
                default:
                        return 0;
                }
        case hwmon_power:
                /* External calibration of receive power requires
                 * floating point arithmetic. Doing that in the kernel
                 * is not easy, so just skip it. If the module does
                 * not require external calibration, we can however
                 * show receiver power, since FP is then not needed.
                 */
                if (sfp->id.ext.diagmon & SFP_DIAGMON_EXT_CAL &&
                    channel == 1)
                        return 0;
                switch (attr) {
                case hwmon_power_min_alarm:
                case hwmon_power_max_alarm:
                case hwmon_power_lcrit_alarm:
                case hwmon_power_crit_alarm:
                case hwmon_power_min:
                case hwmon_power_max:
                case hwmon_power_lcrit:
                case hwmon_power_crit:
                        if (!(sfp->id.ext.enhopts & SFP_ENHOPTS_ALARMWARN))
                                return 0;
                        fallthrough;
                case hwmon_power_input:
                case hwmon_power_label:
                        return 0444;
                default:
                        return 0;
                }
        default:
                return 0;
        }
}

static int sfp_hwmon_read_sensor(struct sfp *sfp, int reg, long *value)
{
        __be16 val;
        int err;

        err = sfp_read(sfp, true, reg, &val, sizeof(val));
        if (err < 0)
                return err;

        *value = be16_to_cpu(val);

        return 0;
}

static void sfp_hwmon_to_rx_power(long *value)
{
        *value = DIV_ROUND_CLOSEST(*value, 10);
}

static void sfp_hwmon_calibrate(struct sfp *sfp, unsigned int slope, int offset,
                                long *value)
{
        if (sfp->id.ext.diagmon & SFP_DIAGMON_EXT_CAL)
                *value = DIV_ROUND_CLOSEST(*value * slope, 256) + offset;
}

static void sfp_hwmon_calibrate_temp(struct sfp *sfp, long *value)
{
        sfp_hwmon_calibrate(sfp, be16_to_cpu(sfp->diag.cal_t_slope),
                            be16_to_cpu(sfp->diag.cal_t_offset), value);

        if (*value >= 0x8000)
                *value -= 0x10000;

        *value = DIV_ROUND_CLOSEST(*value * 1000, 256);
}

static void sfp_hwmon_calibrate_vcc(struct sfp *sfp, long *value)
{
        sfp_hwmon_calibrate(sfp, be16_to_cpu(sfp->diag.cal_v_slope),
                            be16_to_cpu(sfp->diag.cal_v_offset), value);

        *value = DIV_ROUND_CLOSEST(*value, 10);
}

static void sfp_hwmon_calibrate_bias(struct sfp *sfp, long *value)
{
        sfp_hwmon_calibrate(sfp, be16_to_cpu(sfp->diag.cal_txi_slope),
                            be16_to_cpu(sfp->diag.cal_txi_offset), value);

        *value = DIV_ROUND_CLOSEST(*value, 500);
}

static void sfp_hwmon_calibrate_tx_power(struct sfp *sfp, long *value)
{
        sfp_hwmon_calibrate(sfp, be16_to_cpu(sfp->diag.cal_txpwr_slope),
                            be16_to_cpu(sfp->diag.cal_txpwr_offset), value);

        *value = DIV_ROUND_CLOSEST(*value, 10);
}

static int sfp_hwmon_read_temp(struct sfp *sfp, int reg, long *value)
{
        int err;

        err = sfp_hwmon_read_sensor(sfp, reg, value);
        if (err < 0)
                return err;

        sfp_hwmon_calibrate_temp(sfp, value);

        return 0;
}

static int sfp_hwmon_read_vcc(struct sfp *sfp, int reg, long *value)
{
        int err;

        err = sfp_hwmon_read_sensor(sfp, reg, value);
        if (err < 0)
                return err;

        sfp_hwmon_calibrate_vcc(sfp, value);

        return 0;
}

static int sfp_hwmon_read_bias(struct sfp *sfp, int reg, long *value)
{
        int err;

        err = sfp_hwmon_read_sensor(sfp, reg, value);
        if (err < 0)
                return err;

        sfp_hwmon_calibrate_bias(sfp, value);

        return 0;
}

static int sfp_hwmon_read_tx_power(struct sfp *sfp, int reg, long *value)
{
        int err;

        err = sfp_hwmon_read_sensor(sfp, reg, value);
        if (err < 0)
                return err;

        sfp_hwmon_calibrate_tx_power(sfp, value);

        return 0;
}

static int sfp_hwmon_read_rx_power(struct sfp *sfp, int reg, long *value)
{
        int err;

        err = sfp_hwmon_read_sensor(sfp, reg, value);
        if (err < 0)
                return err;

        sfp_hwmon_to_rx_power(value);

        return 0;
}

static int sfp_hwmon_temp(struct sfp *sfp, u32 attr, long *value)
{
        u8 status;
        int err;

        switch (attr) {
        case hwmon_temp_input:
                return sfp_hwmon_read_temp(sfp, SFP_TEMP, value);

        case hwmon_temp_lcrit:
                *value = be16_to_cpu(sfp->diag.temp_low_alarm);
                sfp_hwmon_calibrate_temp(sfp, value);
                return 0;

        case hwmon_temp_min:
                *value = be16_to_cpu(sfp->diag.temp_low_warn);
                sfp_hwmon_calibrate_temp(sfp, value);
                return 0;
        case hwmon_temp_max:
                *value = be16_to_cpu(sfp->diag.temp_high_warn);
                sfp_hwmon_calibrate_temp(sfp, value);
                return 0;

        case hwmon_temp_crit:
                *value = be16_to_cpu(sfp->diag.temp_high_alarm);
                sfp_hwmon_calibrate_temp(sfp, value);
                return 0;

        case hwmon_temp_lcrit_alarm:
                err = sfp_read(sfp, true, SFP_ALARM0, &status, sizeof(status));
                if (err < 0)
                        return err;

                *value = !!(status & SFP_ALARM0_TEMP_LOW);
                return 0;

        case hwmon_temp_min_alarm:
                err = sfp_read(sfp, true, SFP_WARN0, &status, sizeof(status));
                if (err < 0)
                        return err;

                *value = !!(status & SFP_WARN0_TEMP_LOW);
                return 0;

        case hwmon_temp_max_alarm:
                err = sfp_read(sfp, true, SFP_WARN0, &status, sizeof(status));
                if (err < 0)
                        return err;

                *value = !!(status & SFP_WARN0_TEMP_HIGH);
                return 0;

        case hwmon_temp_crit_alarm:
                err = sfp_read(sfp, true, SFP_ALARM0, &status, sizeof(status));
                if (err < 0)
                        return err;

                *value = !!(status & SFP_ALARM0_TEMP_HIGH);
                return 0;
        default:
                return -EOPNOTSUPP;
        }

        return -EOPNOTSUPP;
}

static int sfp_hwmon_vcc(struct sfp *sfp, u32 attr, long *value)
{
        u8 status;
        int err;

        switch (attr) {
        case hwmon_in_input:
                return sfp_hwmon_read_vcc(sfp, SFP_VCC, value);

        case hwmon_in_lcrit:
                *value = be16_to_cpu(sfp->diag.volt_low_alarm);
                sfp_hwmon_calibrate_vcc(sfp, value);
                return 0;

        case hwmon_in_min:
                *value = be16_to_cpu(sfp->diag.volt_low_warn);
                sfp_hwmon_calibrate_vcc(sfp, value);
                return 0;

        case hwmon_in_max:
                *value = be16_to_cpu(sfp->diag.volt_high_warn);
                sfp_hwmon_calibrate_vcc(sfp, value);
                return 0;

        case hwmon_in_crit:
                *value = be16_to_cpu(sfp->diag.volt_high_alarm);
                sfp_hwmon_calibrate_vcc(sfp, value);
                return 0;

        case hwmon_in_lcrit_alarm:
                err = sfp_read(sfp, true, SFP_ALARM0, &status, sizeof(status));
                if (err < 0)
                        return err;

                *value = !!(status & SFP_ALARM0_VCC_LOW);
                return 0;

        case hwmon_in_min_alarm:
                err = sfp_read(sfp, true, SFP_WARN0, &status, sizeof(status));
                if (err < 0)
                        return err;

                *value = !!(status & SFP_WARN0_VCC_LOW);
                return 0;

        case hwmon_in_max_alarm:
                err = sfp_read(sfp, true, SFP_WARN0, &status, sizeof(status));
                if (err < 0)
                        return err;

                *value = !!(status & SFP_WARN0_VCC_HIGH);
                return 0;

        case hwmon_in_crit_alarm:
                err = sfp_read(sfp, true, SFP_ALARM0, &status, sizeof(status));
                if (err < 0)
                        return err;

                *value = !!(status & SFP_ALARM0_VCC_HIGH);
                return 0;
        default:
                return -EOPNOTSUPP;
        }

        return -EOPNOTSUPP;
}

static int sfp_hwmon_bias(struct sfp *sfp, u32 attr, long *value)
{
        u8 status;
        int err;

        switch (attr) {
        case hwmon_curr_input:
                return sfp_hwmon_read_bias(sfp, SFP_TX_BIAS, value);

        case hwmon_curr_lcrit:
                *value = be16_to_cpu(sfp->diag.bias_low_alarm);
                sfp_hwmon_calibrate_bias(sfp, value);
                return 0;

        case hwmon_curr_min:
                *value = be16_to_cpu(sfp->diag.bias_low_warn);
                sfp_hwmon_calibrate_bias(sfp, value);
                return 0;

        case hwmon_curr_max:
                *value = be16_to_cpu(sfp->diag.bias_high_warn);
                sfp_hwmon_calibrate_bias(sfp, value);
                return 0;

        case hwmon_curr_crit:
                *value = be16_to_cpu(sfp->diag.bias_high_alarm);
                sfp_hwmon_calibrate_bias(sfp, value);
                return 0;

        case hwmon_curr_lcrit_alarm:
                err = sfp_read(sfp, true, SFP_ALARM0, &status, sizeof(status));
                if (err < 0)
                        return err;

                *value = !!(status & SFP_ALARM0_TX_BIAS_LOW);
                return 0;

        case hwmon_curr_min_alarm:
                err = sfp_read(sfp, true, SFP_WARN0, &status, sizeof(status));
                if (err < 0)
                        return err;

                *value = !!(status & SFP_WARN0_TX_BIAS_LOW);
                return 0;

        case hwmon_curr_max_alarm:
                err = sfp_read(sfp, true, SFP_WARN0, &status, sizeof(status));
                if (err < 0)
                        return err;

                *value = !!(status & SFP_WARN0_TX_BIAS_HIGH);
                return 0;

        case hwmon_curr_crit_alarm:
                err = sfp_read(sfp, true, SFP_ALARM0, &status, sizeof(status));
                if (err < 0)
                        return err;

                *value = !!(status & SFP_ALARM0_TX_BIAS_HIGH);
                return 0;
        default:
                return -EOPNOTSUPP;
        }

        return -EOPNOTSUPP;
}

static int sfp_hwmon_tx_power(struct sfp *sfp, u32 attr, long *value)
{
        u8 status;
        int err;

        switch (attr) {
        case hwmon_power_input:
                return sfp_hwmon_read_tx_power(sfp, SFP_TX_POWER, value);

        case hwmon_power_lcrit:
                *value = be16_to_cpu(sfp->diag.txpwr_low_alarm);
                sfp_hwmon_calibrate_tx_power(sfp, value);
                return 0;

        case hwmon_power_min:
                *value = be16_to_cpu(sfp->diag.txpwr_low_warn);
                sfp_hwmon_calibrate_tx_power(sfp, value);
                return 0;

        case hwmon_power_max:
                *value = be16_to_cpu(sfp->diag.txpwr_high_warn);
                sfp_hwmon_calibrate_tx_power(sfp, value);

                return 0;

        case hwmon_power_crit:
                *value = be16_to_cpu(sfp->diag.txpwr_high_alarm);
                sfp_hwmon_calibrate_tx_power(sfp, value);
                return 0;

        case hwmon_power_lcrit_alarm:
                err = sfp_read(sfp, true, SFP_ALARM0, &status, sizeof(status));
                if (err < 0)
                        return err;

                *value = !!(status & SFP_ALARM0_TXPWR_LOW);
                return 0;

        case hwmon_power_min_alarm:
                err = sfp_read(sfp, true, SFP_WARN0, &status, sizeof(status));
                if (err < 0)
                        return err;

                *value = !!(status & SFP_WARN0_TXPWR_LOW);
                return 0;

        case hwmon_power_max_alarm:
                err = sfp_read(sfp, true, SFP_WARN0, &status, sizeof(status));
                if (err < 0)
                        return err;

                *value = !!(status & SFP_WARN0_TXPWR_HIGH);
                return 0;

        case hwmon_power_crit_alarm:
                err = sfp_read(sfp, true, SFP_ALARM0, &status, sizeof(status));
                if (err < 0)
                        return err;

                *value = !!(status & SFP_ALARM0_TXPWR_HIGH);
                return 0;
        default:
                return -EOPNOTSUPP;
        }

        return -EOPNOTSUPP;
}

static int sfp_hwmon_rx_power(struct sfp *sfp, u32 attr, long *value)
{
        u8 status;
        int err;

        switch (attr) {
        case hwmon_power_input:
                return sfp_hwmon_read_rx_power(sfp, SFP_RX_POWER, value);

        case hwmon_power_lcrit:
                *value = be16_to_cpu(sfp->diag.rxpwr_low_alarm);
                sfp_hwmon_to_rx_power(value);
                return 0;

        case hwmon_power_min:
                *value = be16_to_cpu(sfp->diag.rxpwr_low_warn);
                sfp_hwmon_to_rx_power(value);
                return 0;

        case hwmon_power_max:
                *value = be16_to_cpu(sfp->diag.rxpwr_high_warn);
                sfp_hwmon_to_rx_power(value);
                return 0;

        case hwmon_power_crit:
                *value = be16_to_cpu(sfp->diag.rxpwr_high_alarm);
                sfp_hwmon_to_rx_power(value);
                return 0;

        case hwmon_power_lcrit_alarm:
                err = sfp_read(sfp, true, SFP_ALARM1, &status, sizeof(status));
                if (err < 0)
                        return err;

                *value = !!(status & SFP_ALARM1_RXPWR_LOW);
                return 0;

        case hwmon_power_min_alarm:
                err = sfp_read(sfp, true, SFP_WARN1, &status, sizeof(status));
                if (err < 0)
                        return err;

                *value = !!(status & SFP_WARN1_RXPWR_LOW);
                return 0;

        case hwmon_power_max_alarm:
                err = sfp_read(sfp, true, SFP_WARN1, &status, sizeof(status));
                if (err < 0)
                        return err;

                *value = !!(status & SFP_WARN1_RXPWR_HIGH);
                return 0;

        case hwmon_power_crit_alarm:
                err = sfp_read(sfp, true, SFP_ALARM1, &status, sizeof(status));
                if (err < 0)
                        return err;

                *value = !!(status & SFP_ALARM1_RXPWR_HIGH);
                return 0;
        default:
                return -EOPNOTSUPP;
        }

        return -EOPNOTSUPP;
}

static int sfp_hwmon_read(struct device *dev, enum hwmon_sensor_types type,
                          u32 attr, int channel, long *value)
{
        struct sfp *sfp = dev_get_drvdata(dev);

        switch (type) {
        case hwmon_temp:
                return sfp_hwmon_temp(sfp, attr, value);
        case hwmon_in:
                return sfp_hwmon_vcc(sfp, attr, value);
        case hwmon_curr:
                return sfp_hwmon_bias(sfp, attr, value);
        case hwmon_power:
                switch (channel) {
                case 0:
                        return sfp_hwmon_tx_power(sfp, attr, value);
                case 1:
                        return sfp_hwmon_rx_power(sfp, attr, value);
                default:
                        return -EOPNOTSUPP;
                }
        default:
                return -EOPNOTSUPP;
        }
}

static const char *const sfp_hwmon_power_labels[] = {
        "TX_power",
        "RX_power",
};

static int sfp_hwmon_read_string(struct device *dev,
                                 enum hwmon_sensor_types type,
                                 u32 attr, int channel, const char **str)
{
        switch (type) {
        case hwmon_curr:
                switch (attr) {
                case hwmon_curr_label:
                        *str = "bias";
                        return 0;
                default:
                        return -EOPNOTSUPP;
                }
                break;
        case hwmon_temp:
                switch (attr) {
                case hwmon_temp_label:
                        *str = "temperature";
                        return 0;
                default:
                        return -EOPNOTSUPP;
                }
                break;
        case hwmon_in:
                switch (attr) {
                case hwmon_in_label:
                        *str = "VCC";
                        return 0;
                default:
                        return -EOPNOTSUPP;
                }
                break;
        case hwmon_power:
                switch (attr) {
                case hwmon_power_label:
                        *str = sfp_hwmon_power_labels[channel];
                        return 0;
                default:
                        return -EOPNOTSUPP;
                }
                break;
        default:
                return -EOPNOTSUPP;
        }

        return -EOPNOTSUPP;
}

static const struct hwmon_ops sfp_hwmon_ops = {
        .is_visible = sfp_hwmon_is_visible,
        .read = sfp_hwmon_read,
        .read_string = sfp_hwmon_read_string,
};

static u32 sfp_hwmon_chip_config[] = {
        HWMON_C_REGISTER_TZ,
        0,
};

static const struct hwmon_channel_info sfp_hwmon_chip = {
        .type = hwmon_chip,
        .config = sfp_hwmon_chip_config,
};

static u32 sfp_hwmon_temp_config[] = {
        HWMON_T_INPUT |
        HWMON_T_MAX | HWMON_T_MIN |
        HWMON_T_MAX_ALARM | HWMON_T_MIN_ALARM |
        HWMON_T_CRIT | HWMON_T_LCRIT |
        HWMON_T_CRIT_ALARM | HWMON_T_LCRIT_ALARM |
        HWMON_T_LABEL,
        0,
};

static const struct hwmon_channel_info sfp_hwmon_temp_channel_info = {
        .type = hwmon_temp,
        .config = sfp_hwmon_temp_config,
};

static u32 sfp_hwmon_vcc_config[] = {
        HWMON_I_INPUT |
        HWMON_I_MAX | HWMON_I_MIN |
        HWMON_I_MAX_ALARM | HWMON_I_MIN_ALARM |
        HWMON_I_CRIT | HWMON_I_LCRIT |
        HWMON_I_CRIT_ALARM | HWMON_I_LCRIT_ALARM |
        HWMON_I_LABEL,
        0,
};

static const struct hwmon_channel_info sfp_hwmon_vcc_channel_info = {
        .type = hwmon_in,
        .config = sfp_hwmon_vcc_config,
};

static u32 sfp_hwmon_bias_config[] = {
        HWMON_C_INPUT |
        HWMON_C_MAX | HWMON_C_MIN |
        HWMON_C_MAX_ALARM | HWMON_C_MIN_ALARM |
        HWMON_C_CRIT | HWMON_C_LCRIT |
        HWMON_C_CRIT_ALARM | HWMON_C_LCRIT_ALARM |
        HWMON_C_LABEL,
        0,
};

static const struct hwmon_channel_info sfp_hwmon_bias_channel_info = {
        .type = hwmon_curr,
        .config = sfp_hwmon_bias_config,
};

static u32 sfp_hwmon_power_config[] = {
        /* Transmit power */
        HWMON_P_INPUT |
        HWMON_P_MAX | HWMON_P_MIN |
        HWMON_P_MAX_ALARM | HWMON_P_MIN_ALARM |
        HWMON_P_CRIT | HWMON_P_LCRIT |
        HWMON_P_CRIT_ALARM | HWMON_P_LCRIT_ALARM |
        HWMON_P_LABEL,
        /* Receive power */
        HWMON_P_INPUT |
        HWMON_P_MAX | HWMON_P_MIN |
        HWMON_P_MAX_ALARM | HWMON_P_MIN_ALARM |
        HWMON_P_CRIT | HWMON_P_LCRIT |
        HWMON_P_CRIT_ALARM | HWMON_P_LCRIT_ALARM |
        HWMON_P_LABEL,
        0,
};

static const struct hwmon_channel_info sfp_hwmon_power_channel_info = {
        .type = hwmon_power,
        .config = sfp_hwmon_power_config,
};

static const struct hwmon_channel_info *sfp_hwmon_info[] = {
        &sfp_hwmon_chip,
        &sfp_hwmon_vcc_channel_info,
        &sfp_hwmon_temp_channel_info,
        &sfp_hwmon_bias_channel_info,
        &sfp_hwmon_power_channel_info,
        NULL,
};

static const struct hwmon_chip_info sfp_hwmon_chip_info = {
        .ops = &sfp_hwmon_ops,
        .info = sfp_hwmon_info,
};

static void sfp_hwmon_probe(struct work_struct *work)
{
        struct sfp *sfp = container_of(work, struct sfp, hwmon_probe.work);
        int err, i;

        /* hwmon interface needs to access 16bit registers in atomic way to
         * guarantee coherency of the diagnostic monitoring data. If it is not
         * possible to guarantee coherency because EEPROM is broken in such way
         * that does not support atomic 16bit read operation then we have to
         * skip registration of hwmon device.
         */
        if (sfp->i2c_block_size < 2) {
                dev_info(sfp->dev,
                         "skipping hwmon device registration due to broken EEPROM\n");
                dev_info(sfp->dev,
                         "diagnostic EEPROM area cannot be read atomically to guarantee data coherency\n");
                return;
        }

        err = sfp_read(sfp, true, 0, &sfp->diag, sizeof(sfp->diag));
        if (err < 0) {
                if (sfp->hwmon_tries--) {
                        mod_delayed_work(system_wq, &sfp->hwmon_probe,
                                         T_PROBE_RETRY_SLOW);
                } else {
                        dev_warn(sfp->dev, "hwmon probe failed: %pe\n",
                                 ERR_PTR(err));
                }
                return;
        }

        sfp->hwmon_name = kstrdup(dev_name(sfp->dev), GFP_KERNEL);
        if (!sfp->hwmon_name) {
                dev_err(sfp->dev, "out of memory for hwmon name\n");
                return;
        }

        for (i = 0; sfp->hwmon_name[i]; i++)
                if (hwmon_is_bad_char(sfp->hwmon_name[i]))
                        sfp->hwmon_name[i] = '_';

        sfp->hwmon_dev = hwmon_device_register_with_info(sfp->dev,
                                                         sfp->hwmon_name, sfp,
                                                         &sfp_hwmon_chip_info,
                                                         NULL);
        if (IS_ERR(sfp->hwmon_dev))
                dev_err(sfp->dev, "failed to register hwmon device: %ld\n",
                        PTR_ERR(sfp->hwmon_dev));
}

static int sfp_hwmon_insert(struct sfp *sfp)
{
        if (sfp->id.ext.sff8472_compliance == SFP_SFF8472_COMPLIANCE_NONE)
                return 0;

        if (!(sfp->id.ext.diagmon & SFP_DIAGMON_DDM))
                return 0;

        if (sfp->id.ext.diagmon & SFP_DIAGMON_ADDRMODE)
                /* This driver in general does not support address
                 * change.
                 */
                return 0;

        mod_delayed_work(system_wq, &sfp->hwmon_probe, 1);
        sfp->hwmon_tries = R_PROBE_RETRY_SLOW;

        return 0;
}

static void sfp_hwmon_remove(struct sfp *sfp)
{
        cancel_delayed_work_sync(&sfp->hwmon_probe);
        if (!IS_ERR_OR_NULL(sfp->hwmon_dev)) {
                hwmon_device_unregister(sfp->hwmon_dev);
                sfp->hwmon_dev = NULL;
                kfree(sfp->hwmon_name);
        }
}

static int sfp_hwmon_init(struct sfp *sfp)
{
        INIT_DELAYED_WORK(&sfp->hwmon_probe, sfp_hwmon_probe);

        return 0;
}

static void sfp_hwmon_exit(struct sfp *sfp)
{
        cancel_delayed_work_sync(&sfp->hwmon_probe);
}
#else
static int sfp_hwmon_insert(struct sfp *sfp)
{
        return 0;
}

static void sfp_hwmon_remove(struct sfp *sfp)
{
}

static int sfp_hwmon_init(struct sfp *sfp)
{
        return 0;
}

static void sfp_hwmon_exit(struct sfp *sfp)
{
}
#endif

/* Helpers */
static void sfp_module_tx_disable(struct sfp *sfp)
{
        dev_dbg(sfp->dev, "tx disable %u -> %u\n",
                sfp->state & SFP_F_TX_DISABLE ? 1 : 0, 1);
        sfp->state |= SFP_F_TX_DISABLE;
        sfp_set_state(sfp, sfp->state);
}

static void sfp_module_tx_enable(struct sfp *sfp)
{
        dev_dbg(sfp->dev, "tx disable %u -> %u\n",
                sfp->state & SFP_F_TX_DISABLE ? 1 : 0, 0);
        sfp->state &= ~SFP_F_TX_DISABLE;
        sfp_set_state(sfp, sfp->state);
}

#if IS_ENABLED(CONFIG_DEBUG_FS)
static int sfp_debug_state_show(struct seq_file *s, void *data)
{
        struct sfp *sfp = s->private;

        seq_printf(s, "Module state: %s\n",
                   mod_state_to_str(sfp->sm_mod_state));
        seq_printf(s, "Module probe attempts: %d %d\n",
                   R_PROBE_RETRY_INIT - sfp->sm_mod_tries_init,
                   R_PROBE_RETRY_SLOW - sfp->sm_mod_tries);
        seq_printf(s, "Device state: %s\n",
                   dev_state_to_str(sfp->sm_dev_state));
        seq_printf(s, "Main state: %s\n",
                   sm_state_to_str(sfp->sm_state));
        seq_printf(s, "Fault recovery remaining retries: %d\n",
                   sfp->sm_fault_retries);
        seq_printf(s, "PHY probe remaining retries: %d\n",
                   sfp->sm_phy_retries);
        seq_printf(s, "moddef0: %d\n", !!(sfp->state & SFP_F_PRESENT));
        seq_printf(s, "rx_los: %d\n", !!(sfp->state & SFP_F_LOS));
        seq_printf(s, "tx_fault: %d\n", !!(sfp->state & SFP_F_TX_FAULT));
        seq_printf(s, "tx_disable: %d\n", !!(sfp->state & SFP_F_TX_DISABLE));
        return 0;
}
DEFINE_SHOW_ATTRIBUTE(sfp_debug_state);

static void sfp_debugfs_init(struct sfp *sfp)
{
        sfp->debugfs_dir = debugfs_create_dir(dev_name(sfp->dev), NULL);

        debugfs_create_file("state", 0600, sfp->debugfs_dir, sfp,
                            &sfp_debug_state_fops);
}

static void sfp_debugfs_exit(struct sfp *sfp)
{
        debugfs_remove_recursive(sfp->debugfs_dir);
}
#else
static void sfp_debugfs_init(struct sfp *sfp)
{
}

static void sfp_debugfs_exit(struct sfp *sfp)
{
}
#endif

static void sfp_module_tx_fault_reset(struct sfp *sfp)
{
        unsigned int state = sfp->state;

        if (state & SFP_F_TX_DISABLE)
                return;

        sfp_set_state(sfp, state | SFP_F_TX_DISABLE);

        udelay(T_RESET_US);

        sfp_set_state(sfp, state);
}

/* SFP state machine */
static void sfp_sm_set_timer(struct sfp *sfp, unsigned int timeout)
{
        if (timeout)
                mod_delayed_work(system_power_efficient_wq, &sfp->timeout,
                                 timeout);
        else
                cancel_delayed_work(&sfp->timeout);
}

static void sfp_sm_next(struct sfp *sfp, unsigned int state,
                        unsigned int timeout)
{
        sfp->sm_state = state;
        sfp_sm_set_timer(sfp, timeout);
}

static void sfp_sm_mod_next(struct sfp *sfp, unsigned int state,
                            unsigned int timeout)
{
        sfp->sm_mod_state = state;
        sfp_sm_set_timer(sfp, timeout);
}

static void sfp_sm_phy_detach(struct sfp *sfp)
{
        sfp_remove_phy(sfp->sfp_bus);
        phy_device_remove(sfp->mod_phy);
        phy_device_free(sfp->mod_phy);
        sfp->mod_phy = NULL;
}

static int sfp_sm_probe_phy(struct sfp *sfp, bool is_c45)
{
        struct phy_device *phy;
        int err;

        phy = get_phy_device(sfp->i2c_mii, SFP_PHY_ADDR, is_c45);
        if (phy == ERR_PTR(-ENODEV))
                return PTR_ERR(phy);
        if (IS_ERR(phy)) {
                dev_err(sfp->dev, "mdiobus scan returned %pe\n", phy);
                return PTR_ERR(phy);
        }

        err = phy_device_register(phy);
        if (err) {
                phy_device_free(phy);
                dev_err(sfp->dev, "phy_device_register failed: %pe\n",
                        ERR_PTR(err));
                return err;
        }

        err = sfp_add_phy(sfp->sfp_bus, phy);
        if (err) {
                phy_device_remove(phy);
                phy_device_free(phy);
                dev_err(sfp->dev, "sfp_add_phy failed: %pe\n", ERR_PTR(err));
                return err;
        }

        sfp->mod_phy = phy;

        return 0;
}

static void sfp_sm_link_up(struct sfp *sfp)
{
        sfp_link_up(sfp->sfp_bus);
        sfp_sm_next(sfp, SFP_S_LINK_UP, 0);
}

static void sfp_sm_link_down(struct sfp *sfp)
{
        sfp_link_down(sfp->sfp_bus);
}

static void sfp_sm_link_check_los(struct sfp *sfp)
{
        const __be16 los_inverted = cpu_to_be16(SFP_OPTIONS_LOS_INVERTED);
        const __be16 los_normal = cpu_to_be16(SFP_OPTIONS_LOS_NORMAL);
        __be16 los_options = sfp->id.ext.options & (los_inverted | los_normal);
        bool los = false;

        /* If neither SFP_OPTIONS_LOS_INVERTED nor SFP_OPTIONS_LOS_NORMAL
         * are set, we assume that no LOS signal is available. If both are
         * set, we assume LOS is not implemented (and is meaningless.)
         */
        if (los_options == los_inverted)
                los = !(sfp->state & SFP_F_LOS);
        else if (los_options == los_normal)
                los = !!(sfp->state & SFP_F_LOS);

        if (los)
                sfp_sm_next(sfp, SFP_S_WAIT_LOS, 0);
        else
                sfp_sm_link_up(sfp);
}

static bool sfp_los_event_active(struct sfp *sfp, unsigned int event)
{
        const __be16 los_inverted = cpu_to_be16(SFP_OPTIONS_LOS_INVERTED);
        const __be16 los_normal = cpu_to_be16(SFP_OPTIONS_LOS_NORMAL);
        __be16 los_options = sfp->id.ext.options & (los_inverted | los_normal);

        return (los_options == los_inverted && event == SFP_E_LOS_LOW) ||
               (los_options == los_normal && event == SFP_E_LOS_HIGH);
}

static bool sfp_los_event_inactive(struct sfp *sfp, unsigned int event)
{
        const __be16 los_inverted = cpu_to_be16(SFP_OPTIONS_LOS_INVERTED);
        const __be16 los_normal = cpu_to_be16(SFP_OPTIONS_LOS_NORMAL);
        __be16 los_options = sfp->id.ext.options & (los_inverted | los_normal);

        return (los_options == los_inverted && event == SFP_E_LOS_HIGH) ||
               (los_options == los_normal && event == SFP_E_LOS_LOW);
}

static void sfp_sm_fault(struct sfp *sfp, unsigned int next_state, bool warn)
{
        if (sfp->sm_fault_retries && !--sfp->sm_fault_retries) {
                dev_err(sfp->dev,
                        "module persistently indicates fault, disabling\n");
                sfp_sm_next(sfp, SFP_S_TX_DISABLE, 0);
        } else {
                if (warn)
                        dev_err(sfp->dev, "module transmit fault indicated\n");

                sfp_sm_next(sfp, next_state, T_FAULT_RECOVER);
        }
}

/* Probe a SFP for a PHY device if the module supports copper - the PHY
 * normally sits at I2C bus address 0x56, and may either be a clause 22
 * or clause 45 PHY.
 *
 * Clause 22 copper SFP modules normally operate in Cisco SGMII mode with
 * negotiation enabled, but some may be in 1000base-X - which is for the
 * PHY driver to determine.
 *
 * Clause 45 copper SFP+ modules (10G) appear to switch their interface
 * mode according to the negotiated line speed.
 */
static int sfp_sm_probe_for_phy(struct sfp *sfp)
{
        int err = 0;

        switch (sfp->id.base.extended_cc) {
        case SFF8024_ECC_10GBASE_T_SFI:
        case SFF8024_ECC_10GBASE_T_SR:
        case SFF8024_ECC_5GBASE_T:
        case SFF8024_ECC_2_5GBASE_T:
                err = sfp_sm_probe_phy(sfp, true);
                break;

        default:
                if (sfp->id.base.e1000_base_t)
                        err = sfp_sm_probe_phy(sfp, false);
                break;
        }
        return err;
}

static int sfp_module_parse_power(struct sfp *sfp)
{
        u32 power_mW = 1000;
        bool supports_a2;

        if (sfp->id.ext.options & cpu_to_be16(SFP_OPTIONS_POWER_DECL))
                power_mW = 1500;
        if (sfp->id.ext.options & cpu_to_be16(SFP_OPTIONS_HIGH_POWER_LEVEL))
                power_mW = 2000;

        supports_a2 = sfp->id.ext.sff8472_compliance !=
                                SFP_SFF8472_COMPLIANCE_NONE ||
                      sfp->id.ext.diagmon & SFP_DIAGMON_DDM;

        if (power_mW > sfp->max_power_mW) {
                /* Module power specification exceeds the allowed maximum. */
                if (!supports_a2) {
                        /* The module appears not to implement bus address
                         * 0xa2, so assume that the module powers up in the
                         * indicated mode.
                         */
                        dev_err(sfp->dev,
                                "Host does not support %u.%uW modules\n",
                                power_mW / 1000, (power_mW / 100) % 10);
                        return -EINVAL;
                } else {
                        dev_warn(sfp->dev,
                                 "Host does not support %u.%uW modules, module left in power mode 1\n",
                                 power_mW / 1000, (power_mW / 100) % 10);
                        return 0;
                }
        }

        if (power_mW <= 1000) {
                /* Modules below 1W do not require a power change sequence */
                sfp->module_power_mW = power_mW;
                return 0;
        }

        if (!supports_a2) {
                /* The module power level is below the host maximum and the
                 * module appears not to implement bus address 0xa2, so assume
                 * that the module powers up in the indicated mode.
                 */
                return 0;
        }

        /* If the module requires a higher power mode, but also requires
         * an address change sequence, warn the user that the module may
         * not be functional.
         */
        if (sfp->id.ext.diagmon & SFP_DIAGMON_ADDRMODE) {
                dev_warn(sfp->dev,
                         "Address Change Sequence not supported but module requires %u.%uW, module may not be functional\n",
                         power_mW / 1000, (power_mW / 100) % 10);
                return 0;
        }

        sfp->module_power_mW = power_mW;

        return 0;
}

static int sfp_sm_mod_hpower(struct sfp *sfp, bool enable)
{
        u8 val;
        int err;

        err = sfp_read(sfp, true, SFP_EXT_STATUS, &val, sizeof(val));
        if (err != sizeof(val)) {
                dev_err(sfp->dev, "Failed to read EEPROM: %pe\n", ERR_PTR(err));
                return -EAGAIN;
        }

        /* DM7052 reports as a high power module, responds to reads (with
         * all bytes 0xff) at 0x51 but does not accept writes.  In any case,
         * if the bit is already set, we're already in high power mode.
         */
        if (!!(val & BIT(0)) == enable)
                return 0;

        if (enable)
                val |= BIT(0);
        else
                val &= ~BIT(0);

        err = sfp_write(sfp, true, SFP_EXT_STATUS, &val, sizeof(val));
        if (err != sizeof(val)) {
                dev_err(sfp->dev, "Failed to write EEPROM: %pe\n",
                        ERR_PTR(err));
                return -EAGAIN;
        }

        if (enable)
                dev_info(sfp->dev, "Module switched to %u.%uW power level\n",
                         sfp->module_power_mW / 1000,
                         (sfp->module_power_mW / 100) % 10);

        return 0;
}

/* GPON modules based on Realtek RTL8672 and RTL9601C chips (e.g. V-SOL
 * V2801F, CarlitoxxPro CPGOS03-0490, Ubiquiti U-Fiber Instant, ...) do
 * not support multibyte reads from the EEPROM. Each multi-byte read
 * operation returns just one byte of EEPROM followed by zeros. There is
 * no way to identify which modules are using Realtek RTL8672 and RTL9601C
 * chips. Moreover every OEM of V-SOL V2801F module puts its own vendor
 * name and vendor id into EEPROM, so there is even no way to detect if
 * module is V-SOL V2801F. Therefore check for those zeros in the read
 * data and then based on check switch to reading EEPROM to one byte
 * at a time.
 */
static bool sfp_id_needs_byte_io(struct sfp *sfp, void *buf, size_t len)
{
        size_t i, block_size = sfp->i2c_block_size;

        /* Already using byte IO */
        if (block_size == 1)
                return false;

        for (i = 1; i < len; i += block_size) {
                if (memchr_inv(buf + i, '\0', min(block_size - 1, len - i)))
                        return false;
        }
        return true;
}

static int sfp_cotsworks_fixup_check(struct sfp *sfp, struct sfp_eeprom_id *id)
{
        u8 check;
        int err;

        if (id->base.phys_id != SFF8024_ID_SFF_8472 ||
            id->base.phys_ext_id != SFP_PHYS_EXT_ID_SFP ||
            id->base.connector != SFF8024_CONNECTOR_LC) {
                dev_warn(sfp->dev, "Rewriting fiber module EEPROM with corrected values\n");
                id->base.phys_id = SFF8024_ID_SFF_8472;
                id->base.phys_ext_id = SFP_PHYS_EXT_ID_SFP;
                id->base.connector = SFF8024_CONNECTOR_LC;
                err = sfp_write(sfp, false, SFP_PHYS_ID, &id->base, 3);
                if (err != 3) {
                        dev_err(sfp->dev,
                                "Failed to rewrite module EEPROM: %pe\n",
                                ERR_PTR(err));
                        return err;
                }

                /* Cotsworks modules have been found to require a delay between write operations. */
                mdelay(50);

                /* Update base structure checksum */
                check = sfp_check(&id->base, sizeof(id->base) - 1);
                err = sfp_write(sfp, false, SFP_CC_BASE, &check, 1);
                if (err != 1) {
                        dev_err(sfp->dev,
                                "Failed to update base structure checksum in fiber module EEPROM: %pe\n",
                                ERR_PTR(err));
                        return err;
                }
        }
        return 0;
}

static int sfp_sm_mod_probe(struct sfp *sfp, bool report)
{
        /* SFP module inserted - read I2C data */
        struct sfp_eeprom_id id;
        bool cotsworks_sfbg;
        bool cotsworks;
        u8 check;
        int ret;

        /* Some SFP modules and also some Linux I2C drivers do not like reads
         * longer than 16 bytes, so read the EEPROM in chunks of 16 bytes at
         * a time.
         */
        sfp->i2c_block_size = 16;

        ret = sfp_read(sfp, false, 0, &id.base, sizeof(id.base));
        if (ret < 0) {
                if (report)
                        dev_err(sfp->dev, "failed to read EEPROM: %pe\n",
                                ERR_PTR(ret));
                return -EAGAIN;
        }

        if (ret != sizeof(id.base)) {
                dev_err(sfp->dev, "EEPROM short read: %pe\n", ERR_PTR(ret));
                return -EAGAIN;
        }

        /* Some SFP modules (e.g. Nokia 3FE46541AA) lock up if read from
         * address 0x51 is just one byte at a time. Also SFF-8472 requires
         * that EEPROM supports atomic 16bit read operation for diagnostic
         * fields, so do not switch to one byte reading at a time unless it
         * is really required and we have no other option.
         */
        if (sfp_id_needs_byte_io(sfp, &id.base, sizeof(id.base))) {
                dev_info(sfp->dev,
                         "Detected broken RTL8672/RTL9601C emulated EEPROM\n");
                dev_info(sfp->dev,
                         "Switching to reading EEPROM to one byte at a time\n");
                sfp->i2c_block_size = 1;

                ret = sfp_read(sfp, false, 0, &id.base, sizeof(id.base));
                if (ret < 0) {
                        if (report)
                                dev_err(sfp->dev,
                                        "failed to read EEPROM: %pe\n",
                                        ERR_PTR(ret));
                        return -EAGAIN;
                }

                if (ret != sizeof(id.base)) {
                        dev_err(sfp->dev, "EEPROM short read: %pe\n",
                                ERR_PTR(ret));
                        return -EAGAIN;
                }
        }

        /* Cotsworks do not seem to update the checksums when they
         * do the final programming with the final module part number,
         * serial number and date code.
         */
        cotsworks = !memcmp(id.base.vendor_name, "COTSWORKS       ", 16);
        cotsworks_sfbg = !memcmp(id.base.vendor_pn, "SFBG", 4);

        /* Cotsworks SFF module EEPROM do not always have valid phys_id,
         * phys_ext_id, and connector bytes.  Rewrite SFF EEPROM bytes if
         * Cotsworks PN matches and bytes are not correct.
         */
        if (cotsworks && cotsworks_sfbg) {
                ret = sfp_cotsworks_fixup_check(sfp, &id);
                if (ret < 0)
                        return ret;
        }

        /* Validate the checksum over the base structure */
        check = sfp_check(&id.base, sizeof(id.base) - 1);
        if (check != id.base.cc_base) {
                if (cotsworks) {
                        dev_warn(sfp->dev,
                                 "EEPROM base structure checksum failure (0x%02x != 0x%02x)\n",
                                 check, id.base.cc_base);
                } else {
                        dev_err(sfp->dev,
                                "EEPROM base structure checksum failure: 0x%02x != 0x%02x\n",
                                check, id.base.cc_base);
                        print_hex_dump(KERN_ERR, "sfp EE: ", DUMP_PREFIX_OFFSET,
                                       16, 1, &id, sizeof(id), true);
                        return -EINVAL;
                }
        }

        ret = sfp_read(sfp, false, SFP_CC_BASE + 1, &id.ext, sizeof(id.ext));
        if (ret < 0) {
                if (report)
                        dev_err(sfp->dev, "failed to read EEPROM: %pe\n",
                                ERR_PTR(ret));
                return -EAGAIN;
        }

        if (ret != sizeof(id.ext)) {
                dev_err(sfp->dev, "EEPROM short read: %pe\n", ERR_PTR(ret));
                return -EAGAIN;
        }

        check = sfp_check(&id.ext, sizeof(id.ext) - 1);
        if (check != id.ext.cc_ext) {
                if (cotsworks) {
                        dev_warn(sfp->dev,
                                 "EEPROM extended structure checksum failure (0x%02x != 0x%02x)\n",
                                 check, id.ext.cc_ext);
                } else {
                        dev_err(sfp->dev,
                                "EEPROM extended structure checksum failure: 0x%02x != 0x%02x\n",
                                check, id.ext.cc_ext);
                        print_hex_dump(KERN_ERR, "sfp EE: ", DUMP_PREFIX_OFFSET,
                                       16, 1, &id, sizeof(id), true);
                        memset(&id.ext, 0, sizeof(id.ext));
                }
        }

        sfp->id = id;

        dev_info(sfp->dev, "module %.*s %.*s rev %.*s sn %.*s dc %.*s\n",
                 (int)sizeof(id.base.vendor_name), id.base.vendor_name,
                 (int)sizeof(id.base.vendor_pn), id.base.vendor_pn,
                 (int)sizeof(id.base.vendor_rev), id.base.vendor_rev,
                 (int)sizeof(id.ext.vendor_sn), id.ext.vendor_sn,
                 (int)sizeof(id.ext.datecode), id.ext.datecode);

        /* Check whether we support this module */
        if (!sfp->type->module_supported(&id)) {
                dev_err(sfp->dev,
                        "module is not supported - phys id 0x%02x 0x%02x\n",
                        sfp->id.base.phys_id, sfp->id.base.phys_ext_id);
                return -EINVAL;
        }

        /* If the module requires address swap mode, warn about it */
        if (sfp->id.ext.diagmon & SFP_DIAGMON_ADDRMODE)
                dev_warn(sfp->dev,
                         "module address swap to access page 0xA2 is not supported.\n");

        /* Parse the module power requirement */
        ret = sfp_module_parse_power(sfp);
        if (ret < 0)
                return ret;

        if (!memcmp(id.base.vendor_name, "ALCATELLUCENT   ", 16) &&
            !memcmp(id.base.vendor_pn, "3FE46541AA      ", 16))
                sfp->module_t_start_up = T_START_UP_BAD_GPON;
        else
                sfp->module_t_start_up = T_START_UP;

        if (!memcmp(id.base.vendor_name, "HUAWEI          ", 16) &&
            !memcmp(id.base.vendor_pn, "MA5671A         ", 16))
                sfp->tx_fault_ignore = true;
        else
                sfp->tx_fault_ignore = false;

        return 0;
}

static void sfp_sm_mod_remove(struct sfp *sfp)
{
        if (sfp->sm_mod_state > SFP_MOD_WAITDEV)
                sfp_module_remove(sfp->sfp_bus);

        sfp_hwmon_remove(sfp);

        memset(&sfp->id, 0, sizeof(sfp->id));
        sfp->module_power_mW = 0;

        dev_info(sfp->dev, "module removed\n");
}

/* This state machine tracks the upstream's state */
static void sfp_sm_device(struct sfp *sfp, unsigned int event)
{
        switch (sfp->sm_dev_state) {
        default:
                if (event == SFP_E_DEV_ATTACH)
                        sfp->sm_dev_state = SFP_DEV_DOWN;
                break;

        case SFP_DEV_DOWN:
                if (event == SFP_E_DEV_DETACH)
                        sfp->sm_dev_state = SFP_DEV_DETACHED;
                else if (event == SFP_E_DEV_UP)
                        sfp->sm_dev_state = SFP_DEV_UP;
                break;

        case SFP_DEV_UP:
                if (event == SFP_E_DEV_DETACH)
                        sfp->sm_dev_state = SFP_DEV_DETACHED;

                else if (event == SFP_E_DEV_DOWN)
                        sfp->sm_dev_state = SFP_DEV_DOWN;
                break;
        }
}

/* This state machine tracks the insert/remove state of the module, probes
 * the on-board EEPROM, and sets up the power level.
 */
static void sfp_sm_module(struct sfp *sfp, unsigned int event)
{
        int err;

        /* Handle remove event globally, it resets this state machine */
        if (event == SFP_E_REMOVE) {
                if (sfp->sm_mod_state > SFP_MOD_PROBE)
                        sfp_sm_mod_remove(sfp);
                sfp_sm_mod_next(sfp, SFP_MOD_EMPTY, 0);
                return;
        }

        /* Handle device detach globally */
        if (sfp->sm_dev_state < SFP_DEV_DOWN &&
            sfp->sm_mod_state > SFP_MOD_WAITDEV) {
                if (sfp->module_power_mW > 1000 &&
                    sfp->sm_mod_state > SFP_MOD_HPOWER)
                        sfp_sm_mod_hpower(sfp, false);
                sfp_sm_mod_next(sfp, SFP_MOD_WAITDEV, 0);
                return;
        }

        switch (sfp->sm_mod_state) {
        default:
                if (event == SFP_E_INSERT) {
                        sfp_sm_mod_next(sfp, SFP_MOD_PROBE, T_SERIAL);
                        sfp->sm_mod_tries_init = R_PROBE_RETRY_INIT;
                        sfp->sm_mod_tries = R_PROBE_RETRY_SLOW;
                }
                break;

        case SFP_MOD_PROBE:
                /* Wait for T_PROBE_INIT to time out */
                if (event != SFP_E_TIMEOUT)
                        break;

                err = sfp_sm_mod_probe(sfp, sfp->sm_mod_tries == 1);
                if (err == -EAGAIN) {
                        if (sfp->sm_mod_tries_init &&
                           --sfp->sm_mod_tries_init) {
                                sfp_sm_set_timer(sfp, T_PROBE_RETRY_INIT);
                                break;
                        } else if (sfp->sm_mod_tries && --sfp->sm_mod_tries) {
                                if (sfp->sm_mod_tries == R_PROBE_RETRY_SLOW - 1)
                                        dev_warn(sfp->dev,
                                                 "please wait, module slow to respond\n");
                                sfp_sm_set_timer(sfp, T_PROBE_RETRY_SLOW);
                                break;
                        }
                }
                if (err < 0) {
                        sfp_sm_mod_next(sfp, SFP_MOD_ERROR, 0);
                        break;
                }

                err = sfp_hwmon_insert(sfp);
                if (err)
                        dev_warn(sfp->dev, "hwmon probe failed: %pe\n",
                                 ERR_PTR(err));

                sfp_sm_mod_next(sfp, SFP_MOD_WAITDEV, 0);
                fallthrough;
        case SFP_MOD_WAITDEV:
                /* Ensure that the device is attached before proceeding */
                if (sfp->sm_dev_state < SFP_DEV_DOWN)
                        break;

                /* Report the module insertion to the upstream device */
                err = sfp_module_insert(sfp->sfp_bus, &sfp->id);
                if (err < 0) {
                        sfp_sm_mod_next(sfp, SFP_MOD_ERROR, 0);
                        break;
                }

                /* If this is a power level 1 module, we are done */
                if (sfp->module_power_mW <= 1000)
                        goto insert;

                sfp_sm_mod_next(sfp, SFP_MOD_HPOWER, 0);
                fallthrough;
        case SFP_MOD_HPOWER:
                /* Enable high power mode */
                err = sfp_sm_mod_hpower(sfp, true);
                if (err < 0) {
                        if (err != -EAGAIN) {
                                sfp_module_remove(sfp->sfp_bus);
                                sfp_sm_mod_next(sfp, SFP_MOD_ERROR, 0);
                        } else {
                                sfp_sm_set_timer(sfp, T_PROBE_RETRY_INIT);
                        }
                        break;
                }

                sfp_sm_mod_next(sfp, SFP_MOD_WAITPWR, T_HPOWER_LEVEL);
                break;

        case SFP_MOD_WAITPWR:
                /* Wait for T_HPOWER_LEVEL to time out */
                if (event != SFP_E_TIMEOUT)
                        break;

        insert:
                sfp_sm_mod_next(sfp, SFP_MOD_PRESENT, 0);
                break;

        case SFP_MOD_PRESENT:
        case SFP_MOD_ERROR:
                break;
        }
}

static void sfp_sm_main(struct sfp *sfp, unsigned int event)
{
        unsigned long timeout;
        int ret;

        /* Some events are global */
        if (sfp->sm_state != SFP_S_DOWN &&
            (sfp->sm_mod_state != SFP_MOD_PRESENT ||
             sfp->sm_dev_state != SFP_DEV_UP)) {
                if (sfp->sm_state == SFP_S_LINK_UP &&
                    sfp->sm_dev_state == SFP_DEV_UP)
                        sfp_sm_link_down(sfp);
                if (sfp->sm_state > SFP_S_INIT)
                        sfp_module_stop(sfp->sfp_bus);
                if (sfp->mod_phy)
                        sfp_sm_phy_detach(sfp);
                sfp_module_tx_disable(sfp);
                sfp_soft_stop_poll(sfp);
                sfp_sm_next(sfp, SFP_S_DOWN, 0);
                return;
        }

        /* The main state machine */
        switch (sfp->sm_state) {
        case SFP_S_DOWN:
                if (sfp->sm_mod_state != SFP_MOD_PRESENT ||
                    sfp->sm_dev_state != SFP_DEV_UP)
                        break;

                if (!(sfp->id.ext.diagmon & SFP_DIAGMON_ADDRMODE))
                        sfp_soft_start_poll(sfp);

                sfp_module_tx_enable(sfp);

                /* Initialise the fault clearance retries */
                sfp->sm_fault_retries = N_FAULT_INIT;

                /* We need to check the TX_FAULT state, which is not defined
                 * while TX_DISABLE is asserted. The earliest we want to do
                 * anything (such as probe for a PHY) is 50ms.
                 */
                sfp_sm_next(sfp, SFP_S_WAIT, T_WAIT);
                break;

        case SFP_S_WAIT:
                if (event != SFP_E_TIMEOUT)
                        break;

                if (sfp->state & SFP_F_TX_FAULT) {
                        /* Wait up to t_init (SFF-8472) or t_start_up (SFF-8431)
                         * from the TX_DISABLE deassertion for the module to
                         * initialise, which is indicated by TX_FAULT
                         * deasserting.
                         */
                        timeout = sfp->module_t_start_up;
                        if (timeout > T_WAIT)
                                timeout -= T_WAIT;
                        else
                                timeout = 1;

                        sfp_sm_next(sfp, SFP_S_INIT, timeout);
                } else {
                        /* TX_FAULT is not asserted, assume the module has
                         * finished initialising.
                         */
                        goto init_done;
                }
                break;

        case SFP_S_INIT:
                if (event == SFP_E_TIMEOUT && sfp->state & SFP_F_TX_FAULT) {
                        /* TX_FAULT is still asserted after t_init
                         * or t_start_up, so assume there is a fault.
                         */
                        sfp_sm_fault(sfp, SFP_S_INIT_TX_FAULT,
                                     sfp->sm_fault_retries == N_FAULT_INIT);
                } else if (event == SFP_E_TIMEOUT || event == SFP_E_TX_CLEAR) {
        init_done:
                        sfp->sm_phy_retries = R_PHY_RETRY;
                        goto phy_probe;
                }
                break;

        case SFP_S_INIT_PHY:
                if (event != SFP_E_TIMEOUT)
                        break;
        phy_probe:
                /* TX_FAULT deasserted or we timed out with TX_FAULT
                 * clear.  Probe for the PHY and check the LOS state.
                 */
                ret = sfp_sm_probe_for_phy(sfp);
                if (ret == -ENODEV) {
                        if (--sfp->sm_phy_retries) {
                                sfp_sm_next(sfp, SFP_S_INIT_PHY, T_PHY_RETRY);
                                break;
                        } else {
                                dev_info(sfp->dev, "no PHY detected\n");
                        }
                } else if (ret) {
                        sfp_sm_next(sfp, SFP_S_FAIL, 0);
                        break;
                }
                if (sfp_module_start(sfp->sfp_bus)) {
                        sfp_sm_next(sfp, SFP_S_FAIL, 0);
                        break;
                }
                sfp_sm_link_check_los(sfp);

                /* Reset the fault retry count */
                sfp->sm_fault_retries = N_FAULT;
                break;

        case SFP_S_INIT_TX_FAULT:
                if (event == SFP_E_TIMEOUT) {
                        sfp_module_tx_fault_reset(sfp);
                        sfp_sm_next(sfp, SFP_S_INIT, sfp->module_t_start_up);
                }
                break;

        case SFP_S_WAIT_LOS:
                if (event == SFP_E_TX_FAULT)
                        sfp_sm_fault(sfp, SFP_S_TX_FAULT, true);
                else if (sfp_los_event_inactive(sfp, event))
                        sfp_sm_link_up(sfp);
                break;

        case SFP_S_LINK_UP:
                if (event == SFP_E_TX_FAULT) {
                        sfp_sm_link_down(sfp);
                        sfp_sm_fault(sfp, SFP_S_TX_FAULT, true);
                } else if (sfp_los_event_active(sfp, event)) {
                        sfp_sm_link_down(sfp);
                        sfp_sm_next(sfp, SFP_S_WAIT_LOS, 0);
                }
                break;

        case SFP_S_TX_FAULT:
                if (event == SFP_E_TIMEOUT) {
                        sfp_module_tx_fault_reset(sfp);
                        sfp_sm_next(sfp, SFP_S_REINIT, sfp->module_t_start_up);
                }
                break;

        case SFP_S_REINIT:
                if (event == SFP_E_TIMEOUT && sfp->state & SFP_F_TX_FAULT) {
                        sfp_sm_fault(sfp, SFP_S_TX_FAULT, false);
                } else if (event == SFP_E_TIMEOUT || event == SFP_E_TX_CLEAR) {
                        dev_info(sfp->dev, "module transmit fault recovered\n");
                        sfp_sm_link_check_los(sfp);
                }
                break;

        case SFP_S_TX_DISABLE:
                break;
        }
}

static void sfp_sm_event(struct sfp *sfp, unsigned int event)
{
        mutex_lock(&sfp->sm_mutex);

        dev_dbg(sfp->dev, "SM: enter %s:%s:%s event %s\n",
                mod_state_to_str(sfp->sm_mod_state),
                dev_state_to_str(sfp->sm_dev_state),
                sm_state_to_str(sfp->sm_state),
                event_to_str(event));

        sfp_sm_device(sfp, event);
        sfp_sm_module(sfp, event);
        sfp_sm_main(sfp, event);

        dev_dbg(sfp->dev, "SM: exit %s:%s:%s\n",
                mod_state_to_str(sfp->sm_mod_state),
                dev_state_to_str(sfp->sm_dev_state),
                sm_state_to_str(sfp->sm_state));

        mutex_unlock(&sfp->sm_mutex);
}

static void sfp_attach(struct sfp *sfp)
{
        sfp_sm_event(sfp, SFP_E_DEV_ATTACH);
}

static void sfp_detach(struct sfp *sfp)
{
        sfp_sm_event(sfp, SFP_E_DEV_DETACH);
}

static void sfp_start(struct sfp *sfp)
{
        sfp_sm_event(sfp, SFP_E_DEV_UP);
}

static void sfp_stop(struct sfp *sfp)
{
        sfp_sm_event(sfp, SFP_E_DEV_DOWN);
}

static int sfp_module_info(struct sfp *sfp, struct ethtool_modinfo *modinfo)
{
        /* locking... and check module is present */

        if (sfp->id.ext.sff8472_compliance &&
            !(sfp->id.ext.diagmon & SFP_DIAGMON_ADDRMODE)) {
                modinfo->type = ETH_MODULE_SFF_8472;
                modinfo->eeprom_len = ETH_MODULE_SFF_8472_LEN;
        } else {
                modinfo->type = ETH_MODULE_SFF_8079;
                modinfo->eeprom_len = ETH_MODULE_SFF_8079_LEN;
        }
        return 0;
}

static int sfp_module_eeprom(struct sfp *sfp, struct ethtool_eeprom *ee,
                             u8 *data)
{
        unsigned int first, last, len;
        int ret;

        if (ee->len == 0)
                return -EINVAL;

        first = ee->offset;
        last = ee->offset + ee->len;
        if (first < ETH_MODULE_SFF_8079_LEN) {
                len = min_t(unsigned int, last, ETH_MODULE_SFF_8079_LEN);
                len -= first;

                ret = sfp_read(sfp, false, first, data, len);
                if (ret < 0)
                        return ret;

                first += len;
                data += len;
        }
        if (first < ETH_MODULE_SFF_8472_LEN && last > ETH_MODULE_SFF_8079_LEN) {
                len = min_t(unsigned int, last, ETH_MODULE_SFF_8472_LEN);
                len -= first;
                first -= ETH_MODULE_SFF_8079_LEN;

                ret = sfp_read(sfp, true, first, data, len);
                if (ret < 0)
                        return ret;
        }
        return 0;
}

static int sfp_module_eeprom_by_page(struct sfp *sfp,
                                     const struct ethtool_module_eeprom *page,
                                     struct netlink_ext_ack *extack)
{
        if (page->bank) {
                NL_SET_ERR_MSG(extack, "Banks not supported");
                return -EOPNOTSUPP;
        }

        if (page->page) {
                NL_SET_ERR_MSG(extack, "Only page 0 supported");
                return -EOPNOTSUPP;
        }

        if (page->i2c_address != 0x50 &&
            page->i2c_address != 0x51) {
                NL_SET_ERR_MSG(extack, "Only address 0x50 and 0x51 supported");
                return -EOPNOTSUPP;
        }

        return sfp_read(sfp, page->i2c_address == 0x51, page->offset,
                        page->data, page->length);
};

static const struct sfp_socket_ops sfp_module_ops = {
        .attach = sfp_attach,
        .detach = sfp_detach,
        .start = sfp_start,
        .stop = sfp_stop,
        .module_info = sfp_module_info,
        .module_eeprom = sfp_module_eeprom,
        .module_eeprom_by_page = sfp_module_eeprom_by_page,
};

static void sfp_timeout(struct work_struct *work)
{
        struct sfp *sfp = container_of(work, struct sfp, timeout.work);

        rtnl_lock();
        sfp_sm_event(sfp, SFP_E_TIMEOUT);
        rtnl_unlock();
}

static void sfp_check_state(struct sfp *sfp)
{
        unsigned int state, i, changed;

        mutex_lock(&sfp->st_mutex);
        state = sfp_get_state(sfp);
        changed = state ^ sfp->state;
        if (sfp->tx_fault_ignore)
                changed &= SFP_F_PRESENT | SFP_F_LOS;
        else
                changed &= SFP_F_PRESENT | SFP_F_LOS | SFP_F_TX_FAULT;

        for (i = 0; i < GPIO_MAX; i++)
                if (changed & BIT(i))
                        dev_dbg(sfp->dev, "%s %u -> %u\n", gpio_of_names[i],
                                !!(sfp->state & BIT(i)), !!(state & BIT(i)));

        state |= sfp->state & (SFP_F_TX_DISABLE | SFP_F_RATE_SELECT);
        sfp->state = state;

        rtnl_lock();
        if (changed & SFP_F_PRESENT)
                sfp_sm_event(sfp, state & SFP_F_PRESENT ?
                                SFP_E_INSERT : SFP_E_REMOVE);

        if (changed & SFP_F_TX_FAULT)
                sfp_sm_event(sfp, state & SFP_F_TX_FAULT ?
                                SFP_E_TX_FAULT : SFP_E_TX_CLEAR);

        if (changed & SFP_F_LOS)
                sfp_sm_event(sfp, state & SFP_F_LOS ?
                                SFP_E_LOS_HIGH : SFP_E_LOS_LOW);
        rtnl_unlock();
        mutex_unlock(&sfp->st_mutex);
}

static irqreturn_t sfp_irq(int irq, void *data)
{
        struct sfp *sfp = data;

        sfp_check_state(sfp);

        return IRQ_HANDLED;
}

static void sfp_poll(struct work_struct *work)
{
        struct sfp *sfp = container_of(work, struct sfp, poll.work);

        sfp_check_state(sfp);

        if (sfp->state_soft_mask & (SFP_F_LOS | SFP_F_TX_FAULT) ||
            sfp->need_poll)
                mod_delayed_work(system_wq, &sfp->poll, poll_jiffies);
}

static struct sfp *sfp_alloc(struct device *dev)
{
        struct sfp *sfp;

        sfp = kzalloc(sizeof(*sfp), GFP_KERNEL);
        if (!sfp)
                return ERR_PTR(-ENOMEM);

        sfp->dev = dev;

        mutex_init(&sfp->sm_mutex);
        mutex_init(&sfp->st_mutex);
        INIT_DELAYED_WORK(&sfp->poll, sfp_poll);
        INIT_DELAYED_WORK(&sfp->timeout, sfp_timeout);

        sfp_hwmon_init(sfp);

        return sfp;
}

static void sfp_cleanup(void *data)
{
        struct sfp *sfp = data;

        sfp_hwmon_exit(sfp);

        cancel_delayed_work_sync(&sfp->poll);
        cancel_delayed_work_sync(&sfp->timeout);
        if (sfp->i2c_mii) {
                mdiobus_unregister(sfp->i2c_mii);
                mdiobus_free(sfp->i2c_mii);
        }
        if (sfp->i2c)
                i2c_put_adapter(sfp->i2c);
        kfree(sfp);
}

static int sfp_probe(struct platform_device *pdev)
{
        const struct sff_data *sff;
        struct i2c_adapter *i2c;
        char *sfp_irq_name;
        struct sfp *sfp;
        int err, i;

        sfp = sfp_alloc(&pdev->dev);
        if (IS_ERR(sfp))
                return PTR_ERR(sfp);

        platform_set_drvdata(pdev, sfp);

        err = devm_add_action_or_reset(sfp->dev, sfp_cleanup, sfp);
        if (err < 0)
                return err;

        sff = sfp->type = &sfp_data;

        if (pdev->dev.of_node) {
                struct device_node *node = pdev->dev.of_node;
                const struct of_device_id *id;
                struct device_node *np;

                id = of_match_node(sfp_of_match, node);
                if (WARN_ON(!id))
                        return -EINVAL;

                sff = sfp->type = id->data;

                np = of_parse_phandle(node, "i2c-bus", 0);
                if (!np) {
                        dev_err(sfp->dev, "missing 'i2c-bus' property\n");
                        return -ENODEV;
                }

                i2c = of_find_i2c_adapter_by_node(np);
                of_node_put(np);
        } else if (has_acpi_companion(&pdev->dev)) {
                struct acpi_device *adev = ACPI_COMPANION(&pdev->dev);
                struct fwnode_handle *fw = acpi_fwnode_handle(adev);
                struct fwnode_reference_args args;
                struct acpi_handle *acpi_handle;
                int ret;

                ret = acpi_node_get_property_reference(fw, "i2c-bus", 0, &args);
                if (ret || !is_acpi_device_node(args.fwnode)) {
                        dev_err(&pdev->dev, "missing 'i2c-bus' property\n");
                        return -ENODEV;
                }

                acpi_handle = ACPI_HANDLE_FWNODE(args.fwnode);
                i2c = i2c_acpi_find_adapter_by_handle(acpi_handle);
        } else {
                return -EINVAL;
        }

        if (!i2c)
                return -EPROBE_DEFER;

        err = sfp_i2c_configure(sfp, i2c);
        if (err < 0) {
                i2c_put_adapter(i2c);
                return err;
        }

        for (i = 0; i < GPIO_MAX; i++)
                if (sff->gpios & BIT(i)) {
                        sfp->gpio[i] = devm_gpiod_get_optional(sfp->dev,
                                           gpio_of_names[i], gpio_flags[i]);
                        if (IS_ERR(sfp->gpio[i]))
                                return PTR_ERR(sfp->gpio[i]);
                }

        sfp->get_state = sfp_gpio_get_state;
        sfp->set_state = sfp_gpio_set_state;

        /* Modules that have no detect signal are always present */
        if (!(sfp->gpio[GPIO_MODDEF0]))
                sfp->get_state = sff_gpio_get_state;

        device_property_read_u32(&pdev->dev, "maximum-power-milliwatt",
                                 &sfp->max_power_mW);
        if (!sfp->max_power_mW)
                sfp->max_power_mW = 1000;

        dev_info(sfp->dev, "Host maximum power %u.%uW\n",
                 sfp->max_power_mW / 1000, (sfp->max_power_mW / 100) % 10);

        /* Get the initial state, and always signal TX disable,
         * since the network interface will not be up.
         */
        sfp->state = sfp_get_state(sfp) | SFP_F_TX_DISABLE;

        if (sfp->gpio[GPIO_RATE_SELECT] &&
            gpiod_get_value_cansleep(sfp->gpio[GPIO_RATE_SELECT]))
                sfp->state |= SFP_F_RATE_SELECT;
        sfp_set_state(sfp, sfp->state);
        sfp_module_tx_disable(sfp);
        if (sfp->state & SFP_F_PRESENT) {
                rtnl_lock();
                sfp_sm_event(sfp, SFP_E_INSERT);
                rtnl_unlock();
        }

        for (i = 0; i < GPIO_MAX; i++) {
                if (gpio_flags[i] != GPIOD_IN || !sfp->gpio[i])
                        continue;

                sfp->gpio_irq[i] = gpiod_to_irq(sfp->gpio[i]);
                if (sfp->gpio_irq[i] < 0) {
                        sfp->gpio_irq[i] = 0;
                        sfp->need_poll = true;
                        continue;
                }

                sfp_irq_name = devm_kasprintf(sfp->dev, GFP_KERNEL,
                                              "%s-%s", dev_name(sfp->dev),
                                              gpio_of_names[i]);

                if (!sfp_irq_name)
                        return -ENOMEM;

                err = devm_request_threaded_irq(sfp->dev, sfp->gpio_irq[i],
                                                NULL, sfp_irq,
                                                IRQF_ONESHOT |
                                                IRQF_TRIGGER_RISING |
                                                IRQF_TRIGGER_FALLING,
                                                sfp_irq_name, sfp);
                if (err) {
                        sfp->gpio_irq[i] = 0;
                        sfp->need_poll = true;
                }
        }

        if (sfp->need_poll)
                mod_delayed_work(system_wq, &sfp->poll, poll_jiffies);

        /* We could have an issue in cases no Tx disable pin is available or
         * wired as modules using a laser as their light source will continue to
         * be active when the fiber is removed. This could be a safety issue and
         * we should at least warn the user about that.
         */
        if (!sfp->gpio[GPIO_TX_DISABLE])
                dev_warn(sfp->dev,
                         "No tx_disable pin: SFP modules will always be emitting.\n");

        sfp->sfp_bus = sfp_register_socket(sfp->dev, sfp, &sfp_module_ops);
        if (!sfp->sfp_bus)
                return -ENOMEM;

        sfp_debugfs_init(sfp);

        return 0;
}

static int sfp_remove(struct platform_device *pdev)
{
        struct sfp *sfp = platform_get_drvdata(pdev);

        sfp_debugfs_exit(sfp);
        sfp_unregister_socket(sfp->sfp_bus);

        rtnl_lock();
        sfp_sm_event(sfp, SFP_E_REMOVE);
        rtnl_unlock();

        return 0;
}

static void sfp_shutdown(struct platform_device *pdev)
{
        struct sfp *sfp = platform_get_drvdata(pdev);
        int i;

        for (i = 0; i < GPIO_MAX; i++) {
                if (!sfp->gpio_irq[i])
                        continue;

                devm_free_irq(sfp->dev, sfp->gpio_irq[i], sfp);
        }

        cancel_delayed_work_sync(&sfp->poll);
        cancel_delayed_work_sync(&sfp->timeout);
}

static struct platform_driver sfp_driver = {
        .probe = sfp_probe,
        .remove = sfp_remove,
        .shutdown = sfp_shutdown,
        .driver = {
                .name = "sfp",
                .of_match_table = sfp_of_match,
        },
};

static int sfp_init(void)
{
        poll_jiffies = msecs_to_jiffies(100);

        return platform_driver_register(&sfp_driver);
}
module_init(sfp_init);

static void sfp_exit(void)
{
        platform_driver_unregister(&sfp_driver);
}
module_exit(sfp_exit);

MODULE_ALIAS("platform:sfp");
MODULE_AUTHOR("Russell King");
MODULE_LICENSE("GPL v2");