// SPDX-License-Identifier: (GPL-2.0-or-later OR BSD-3-Clause)
/*
 * Copyright (c) 2014-2025, Advanced Micro Devices, Inc.
 * Copyright (c) 2014, Synopsys, Inc.
 * All rights reserved
 */

#include <linux/module.h>
#include <linux/interrupt.h>
#include <linux/kmod.h>
#include <linux/delay.h>
#include <linux/completion.h>
#include <linux/mutex.h>

#include "xgbe.h"
#include "xgbe-common.h"

#define XGBE_ABORT_COUNT        500
#define XGBE_DISABLE_COUNT      1000

#define XGBE_STD_SPEED          1

#define XGBE_INTR_RX_FULL       BIT(IC_RAW_INTR_STAT_RX_FULL_INDEX)
#define XGBE_INTR_TX_EMPTY      BIT(IC_RAW_INTR_STAT_TX_EMPTY_INDEX)
#define XGBE_INTR_TX_ABRT       BIT(IC_RAW_INTR_STAT_TX_ABRT_INDEX)
#define XGBE_INTR_STOP_DET      BIT(IC_RAW_INTR_STAT_STOP_DET_INDEX)
#define XGBE_DEFAULT_INT_MASK   (XGBE_INTR_RX_FULL  |   \
                                 XGBE_INTR_TX_EMPTY |   \
                                 XGBE_INTR_TX_ABRT  |   \
                                 XGBE_INTR_STOP_DET)

#define XGBE_I2C_READ           BIT(8)
#define XGBE_I2C_STOP           BIT(9)

static int xgbe_i2c_abort(struct xgbe_prv_data *pdata)
{
        unsigned int wait = XGBE_ABORT_COUNT;

        /* Must be enabled to recognize the abort request */
        XI2C_IOWRITE_BITS(pdata, IC_ENABLE, EN, 1);

        /* Issue the abort */
        XI2C_IOWRITE_BITS(pdata, IC_ENABLE, ABORT, 1);

        while (wait--) {
                if (!XI2C_IOREAD_BITS(pdata, IC_ENABLE, ABORT))
                        return 0;

                usleep_range(500, 600);
        }

        return -EBUSY;
}

static int xgbe_i2c_set_enable(struct xgbe_prv_data *pdata, bool enable)
{
        unsigned int wait = XGBE_DISABLE_COUNT;
        unsigned int mode = enable ? 1 : 0;

        while (wait--) {
                XI2C_IOWRITE_BITS(pdata, IC_ENABLE, EN, mode);
                if (XI2C_IOREAD_BITS(pdata, IC_ENABLE_STATUS, EN) == mode)
                        return 0;

                usleep_range(100, 110);
        }

        return -EBUSY;
}

static int xgbe_i2c_disable(struct xgbe_prv_data *pdata)
{
        int ret;

        ret = xgbe_i2c_set_enable(pdata, false);
        if (ret) {
                /* Disable failed, try an abort */
                ret = xgbe_i2c_abort(pdata);
                if (ret)
                        return ret;

                /* Abort succeeded, try to disable again */
                ret = xgbe_i2c_set_enable(pdata, false);
        }

        return ret;
}

static int xgbe_i2c_enable(struct xgbe_prv_data *pdata)
{
        return xgbe_i2c_set_enable(pdata, true);
}

static void xgbe_i2c_clear_all_interrupts(struct xgbe_prv_data *pdata)
{
        XI2C_IOREAD(pdata, IC_CLR_INTR);
}

static void xgbe_i2c_disable_interrupts(struct xgbe_prv_data *pdata)
{
        XI2C_IOWRITE(pdata, IC_INTR_MASK, 0);
}

static void xgbe_i2c_enable_interrupts(struct xgbe_prv_data *pdata)
{
        XI2C_IOWRITE(pdata, IC_INTR_MASK, XGBE_DEFAULT_INT_MASK);
}

static void xgbe_i2c_write(struct xgbe_prv_data *pdata)
{
        struct xgbe_i2c_op_state *state = &pdata->i2c.op_state;
        unsigned int tx_slots;
        unsigned int cmd;

        /* Configured to never receive Rx overflows, so fill up Tx fifo */
        tx_slots = pdata->i2c.tx_fifo_size - XI2C_IOREAD(pdata, IC_TXFLR);
        while (tx_slots && state->tx_len) {
                if (state->op->cmd == XGBE_I2C_CMD_READ)
                        cmd = XGBE_I2C_READ;
                else
                        cmd = *state->tx_buf++;

                if (state->tx_len == 1)
                        XI2C_SET_BITS(cmd, IC_DATA_CMD, STOP, 1);

                XI2C_IOWRITE(pdata, IC_DATA_CMD, cmd);

                tx_slots--;
                state->tx_len--;
        }

        /* No more Tx operations, so ignore TX_EMPTY and return */
        if (!state->tx_len)
                XI2C_IOWRITE_BITS(pdata, IC_INTR_MASK, TX_EMPTY, 0);
}

static void xgbe_i2c_read(struct xgbe_prv_data *pdata)
{
        struct xgbe_i2c_op_state *state = &pdata->i2c.op_state;
        unsigned int rx_slots;

        /* Anything to be read? */
        if (state->op->cmd != XGBE_I2C_CMD_READ)
                return;

        rx_slots = XI2C_IOREAD(pdata, IC_RXFLR);
        while (rx_slots && state->rx_len) {
                *state->rx_buf++ = XI2C_IOREAD(pdata, IC_DATA_CMD);
                state->rx_len--;
                rx_slots--;
        }
}

static void xgbe_i2c_clear_isr_interrupts(struct xgbe_prv_data *pdata,
                                          unsigned int isr)
{
        struct xgbe_i2c_op_state *state = &pdata->i2c.op_state;

        if (isr & XGBE_INTR_TX_ABRT) {
                state->tx_abort_source = XI2C_IOREAD(pdata, IC_TX_ABRT_SOURCE);
                XI2C_IOREAD(pdata, IC_CLR_TX_ABRT);
        }

        if (isr & XGBE_INTR_STOP_DET)
                XI2C_IOREAD(pdata, IC_CLR_STOP_DET);
}

static void xgbe_i2c_isr_bh_work(struct work_struct *work)
{
        struct xgbe_prv_data *pdata = from_work(pdata, work, i2c_bh_work);
        struct xgbe_i2c_op_state *state = &pdata->i2c.op_state;
        unsigned int isr;

        isr = XI2C_IOREAD(pdata, IC_RAW_INTR_STAT);
        if (!isr)
                goto reissue_check;

        netif_dbg(pdata, intr, pdata->netdev,
                  "I2C interrupt received: status=%#010x\n", isr);

        xgbe_i2c_clear_isr_interrupts(pdata, isr);

        if (isr & XGBE_INTR_TX_ABRT) {
                netif_dbg(pdata, link, pdata->netdev,
                          "I2C TX_ABRT received (%#010x) for target %#04x\n",
                          state->tx_abort_source, state->op->target);

                xgbe_i2c_disable_interrupts(pdata);

                state->ret = -EIO;
                goto out;
        }

        /* Check for data in the Rx fifo */
        xgbe_i2c_read(pdata);

        /* Fill up the Tx fifo next */
        xgbe_i2c_write(pdata);

out:
        /* Complete on an error or STOP condition */
        if (state->ret || XI2C_GET_BITS(isr, IC_RAW_INTR_STAT, STOP_DET))
                complete(&pdata->i2c_complete);

reissue_check:
        /* Reissue interrupt if status is not clear */
        if (pdata->vdata->irq_reissue_support)
                XP_IOWRITE(pdata, XP_INT_REISSUE_EN, 1 << 2);
}

static irqreturn_t xgbe_i2c_isr(int irq, void *data)
{
        struct xgbe_prv_data *pdata = (struct xgbe_prv_data *)data;

        if (pdata->isr_as_bh_work)
                queue_work(system_bh_wq, &pdata->i2c_bh_work);
        else
                xgbe_i2c_isr_bh_work(&pdata->i2c_bh_work);

        return IRQ_HANDLED;
}

static void xgbe_i2c_set_mode(struct xgbe_prv_data *pdata)
{
        unsigned int reg;

        reg = XI2C_IOREAD(pdata, IC_CON);
        XI2C_SET_BITS(reg, IC_CON, MASTER_MODE, 1);
        XI2C_SET_BITS(reg, IC_CON, SLAVE_DISABLE, 1);
        XI2C_SET_BITS(reg, IC_CON, RESTART_EN, 1);
        XI2C_SET_BITS(reg, IC_CON, SPEED, XGBE_STD_SPEED);
        XI2C_SET_BITS(reg, IC_CON, RX_FIFO_FULL_HOLD, 1);
        XI2C_IOWRITE(pdata, IC_CON, reg);
}

static void xgbe_i2c_get_features(struct xgbe_prv_data *pdata)
{
        struct xgbe_i2c *i2c = &pdata->i2c;
        unsigned int reg;

        reg = XI2C_IOREAD(pdata, IC_COMP_PARAM_1);
        i2c->max_speed_mode = XI2C_GET_BITS(reg, IC_COMP_PARAM_1,
                                            MAX_SPEED_MODE);
        i2c->rx_fifo_size = XI2C_GET_BITS(reg, IC_COMP_PARAM_1,
                                          RX_BUFFER_DEPTH);
        i2c->tx_fifo_size = XI2C_GET_BITS(reg, IC_COMP_PARAM_1,
                                          TX_BUFFER_DEPTH);

        if (netif_msg_probe(pdata))
                dev_dbg(pdata->dev, "I2C features: %s=%u, %s=%u, %s=%u\n",
                        "MAX_SPEED_MODE", i2c->max_speed_mode,
                        "RX_BUFFER_DEPTH", i2c->rx_fifo_size,
                        "TX_BUFFER_DEPTH", i2c->tx_fifo_size);
}

static void xgbe_i2c_set_target(struct xgbe_prv_data *pdata, unsigned int addr)
{
        XI2C_IOWRITE(pdata, IC_TAR, addr);
}

static irqreturn_t xgbe_i2c_combined_isr(struct xgbe_prv_data *pdata)
{
        xgbe_i2c_isr_bh_work(&pdata->i2c_bh_work);

        return IRQ_HANDLED;
}

static int xgbe_i2c_xfer(struct xgbe_prv_data *pdata, struct xgbe_i2c_op *op)
{
        struct xgbe_i2c_op_state *state = &pdata->i2c.op_state;
        int ret;

        mutex_lock(&pdata->i2c_mutex);

        reinit_completion(&pdata->i2c_complete);

        ret = xgbe_i2c_disable(pdata);
        if (ret) {
                netdev_err(pdata->netdev, "failed to disable i2c master\n");
                goto unlock;
        }

        xgbe_i2c_set_target(pdata, op->target);

        memset(state, 0, sizeof(*state));
        state->op = op;
        state->tx_len = op->len;
        state->tx_buf = op->buf;
        state->rx_len = op->len;
        state->rx_buf = op->buf;

        xgbe_i2c_clear_all_interrupts(pdata);
        ret = xgbe_i2c_enable(pdata);
        if (ret) {
                netdev_err(pdata->netdev, "failed to enable i2c master\n");
                goto unlock;
        }

        /* Enabling the interrupts will cause the TX FIFO empty interrupt to
         * fire and begin to process the command via the ISR.
         */
        xgbe_i2c_enable_interrupts(pdata);

        if (!wait_for_completion_timeout(&pdata->i2c_complete, HZ)) {
                netdev_err(pdata->netdev, "i2c operation timed out\n");
                ret = -ETIMEDOUT;
                goto disable;
        }

        ret = state->ret;
        if (ret) {
                if (state->tx_abort_source & IC_TX_ABRT_7B_ADDR_NOACK)
                        ret = -ENOTCONN;
                else if (state->tx_abort_source & IC_TX_ABRT_ARB_LOST)
                        ret = -EAGAIN;
        }

disable:
        xgbe_i2c_disable_interrupts(pdata);
        xgbe_i2c_disable(pdata);

unlock:
        mutex_unlock(&pdata->i2c_mutex);

        return ret;
}

static void xgbe_i2c_stop(struct xgbe_prv_data *pdata)
{
        if (!pdata->i2c.started)
                return;

        netif_dbg(pdata, link, pdata->netdev, "stopping I2C\n");

        pdata->i2c.started = 0;

        xgbe_i2c_disable_interrupts(pdata);
        xgbe_i2c_disable(pdata);
        xgbe_i2c_clear_all_interrupts(pdata);

        if (pdata->dev_irq != pdata->i2c_irq) {
                devm_free_irq(pdata->dev, pdata->i2c_irq, pdata);
                cancel_work_sync(&pdata->i2c_bh_work);
        }
}

static int xgbe_i2c_start(struct xgbe_prv_data *pdata)
{
        int ret;

        if (pdata->i2c.started)
                return 0;

        netif_dbg(pdata, link, pdata->netdev, "starting I2C\n");

        /* If we have a separate I2C irq, enable it */
        if (pdata->dev_irq != pdata->i2c_irq) {
                INIT_WORK(&pdata->i2c_bh_work, xgbe_i2c_isr_bh_work);

                ret = devm_request_irq(pdata->dev, pdata->i2c_irq,
                                       xgbe_i2c_isr, 0, pdata->i2c_name,
                                       pdata);
                if (ret) {
                        netdev_err(pdata->netdev, "i2c irq request failed\n");
                        return ret;
                }
        }

        pdata->i2c.started = 1;

        return 0;
}

static int xgbe_i2c_init(struct xgbe_prv_data *pdata)
{
        int ret;

        xgbe_i2c_disable_interrupts(pdata);

        ret = xgbe_i2c_disable(pdata);
        if (ret) {
                dev_err(pdata->dev, "failed to disable i2c master\n");
                return ret;
        }

        xgbe_i2c_get_features(pdata);

        xgbe_i2c_set_mode(pdata);

        xgbe_i2c_clear_all_interrupts(pdata);

        return 0;
}

void xgbe_init_function_ptrs_i2c(struct xgbe_i2c_if *i2c_if)
{
        i2c_if->i2c_init                = xgbe_i2c_init;

        i2c_if->i2c_start               = xgbe_i2c_start;
        i2c_if->i2c_stop                = xgbe_i2c_stop;

        i2c_if->i2c_xfer                = xgbe_i2c_xfer;

        i2c_if->i2c_isr                 = xgbe_i2c_combined_isr;
}