// SPDX-License-Identifier: GPL-2.0-only
/*
 * Copyright (c) 2012-2020, The Linux Foundation. All rights reserved.
 */

#include <linux/delay.h>
#include <drm/drm_print.h>

#include "dp_reg.h"
#include "dp_aux.h"

enum msm_dp_aux_err {
        DP_AUX_ERR_NONE,
        DP_AUX_ERR_ADDR,
        DP_AUX_ERR_TOUT,
        DP_AUX_ERR_NACK,
        DP_AUX_ERR_DEFER,
        DP_AUX_ERR_NACK_DEFER,
        DP_AUX_ERR_PHY,
};

struct dp_aux_private {
        struct device *dev;
        struct dp_catalog *catalog;

        struct mutex mutex;
        struct completion comp;

        enum msm_dp_aux_err aux_error_num;
        u32 retry_cnt;
        bool cmd_busy;
        bool native;
        bool read;
        bool no_send_addr;
        bool no_send_stop;
        u32 offset;
        u32 segment;

        struct drm_dp_aux dp_aux;
};

#define MAX_AUX_RETRIES                 5

static ssize_t dp_aux_write(struct dp_aux_private *aux,
                        struct drm_dp_aux_msg *msg)
{
        u8 data[4];
        u32 reg;
        ssize_t len;
        u8 *msgdata = msg->buffer;
        int const AUX_CMD_FIFO_LEN = 128;
        int i = 0;

        if (aux->read)
                len = 0;
        else
                len = msg->size;

        /*
         * cmd fifo only has depth of 144 bytes
         * limit buf length to 128 bytes here
         */
        if (len > AUX_CMD_FIFO_LEN - 4) {
                DRM_ERROR("buf size greater than allowed size of 128 bytes\n");
                return -EINVAL;
        }

        /* Pack cmd and write to HW */
        data[0] = (msg->address >> 16) & 0xf;   /* addr[19:16] */
        if (aux->read)
                data[0] |=  BIT(4);             /* R/W */

        data[1] = msg->address >> 8;            /* addr[15:8] */
        data[2] = msg->address;                 /* addr[7:0] */
        data[3] = msg->size - 1;                /* len[7:0] */

        for (i = 0; i < len + 4; i++) {
                reg = (i < 4) ? data[i] : msgdata[i - 4];
                reg <<= DP_AUX_DATA_OFFSET;
                reg &= DP_AUX_DATA_MASK;
                reg |= DP_AUX_DATA_WRITE;
                /* index = 0, write */
                if (i == 0)
                        reg |= DP_AUX_DATA_INDEX_WRITE;
                aux->catalog->aux_data = reg;
                dp_catalog_aux_write_data(aux->catalog);
        }

        dp_catalog_aux_clear_trans(aux->catalog, false);
        dp_catalog_aux_clear_hw_interrupts(aux->catalog);

        reg = 0; /* Transaction number == 1 */
        if (!aux->native) { /* i2c */
                reg |= DP_AUX_TRANS_CTRL_I2C;

                if (aux->no_send_addr)
                        reg |= DP_AUX_TRANS_CTRL_NO_SEND_ADDR;

                if (aux->no_send_stop)
                        reg |= DP_AUX_TRANS_CTRL_NO_SEND_STOP;
        }

        reg |= DP_AUX_TRANS_CTRL_GO;
        aux->catalog->aux_data = reg;
        dp_catalog_aux_write_trans(aux->catalog);

        return len;
}

static ssize_t dp_aux_cmd_fifo_tx(struct dp_aux_private *aux,
                              struct drm_dp_aux_msg *msg)
{
        ssize_t ret;
        unsigned long time_left;

        reinit_completion(&aux->comp);

        ret = dp_aux_write(aux, msg);
        if (ret < 0)
                return ret;

        time_left = wait_for_completion_timeout(&aux->comp,
                                                msecs_to_jiffies(250));
        if (!time_left)
                return -ETIMEDOUT;

        return ret;
}

static ssize_t dp_aux_cmd_fifo_rx(struct dp_aux_private *aux,
                struct drm_dp_aux_msg *msg)
{
        u32 data;
        u8 *dp;
        u32 i, actual_i;
        u32 len = msg->size;

        dp_catalog_aux_clear_trans(aux->catalog, true);

        data = DP_AUX_DATA_INDEX_WRITE; /* INDEX_WRITE */
        data |= DP_AUX_DATA_READ;  /* read */

        aux->catalog->aux_data = data;
        dp_catalog_aux_write_data(aux->catalog);

        dp = msg->buffer;

        /* discard first byte */
        data = dp_catalog_aux_read_data(aux->catalog);

        for (i = 0; i < len; i++) {
                data = dp_catalog_aux_read_data(aux->catalog);
                *dp++ = (u8)((data >> DP_AUX_DATA_OFFSET) & 0xff);

                actual_i = (data >> DP_AUX_DATA_INDEX_OFFSET) & 0xFF;
                if (i != actual_i)
                        break;
        }

        return i;
}

static void dp_aux_native_handler(struct dp_aux_private *aux, u32 isr)
{
        if (isr & DP_INTR_AUX_I2C_DONE)
                aux->aux_error_num = DP_AUX_ERR_NONE;
        else if (isr & DP_INTR_WRONG_ADDR)
                aux->aux_error_num = DP_AUX_ERR_ADDR;
        else if (isr & DP_INTR_TIMEOUT)
                aux->aux_error_num = DP_AUX_ERR_TOUT;
        if (isr & DP_INTR_NACK_DEFER)
                aux->aux_error_num = DP_AUX_ERR_NACK;
        if (isr & DP_INTR_AUX_ERROR) {
                aux->aux_error_num = DP_AUX_ERR_PHY;
                dp_catalog_aux_clear_hw_interrupts(aux->catalog);
        }
}

static void dp_aux_i2c_handler(struct dp_aux_private *aux, u32 isr)
{
        if (isr & DP_INTR_AUX_I2C_DONE) {
                if (isr & (DP_INTR_I2C_NACK | DP_INTR_I2C_DEFER))
                        aux->aux_error_num = DP_AUX_ERR_NACK;
                else
                        aux->aux_error_num = DP_AUX_ERR_NONE;
        } else {
                if (isr & DP_INTR_WRONG_ADDR)
                        aux->aux_error_num = DP_AUX_ERR_ADDR;
                else if (isr & DP_INTR_TIMEOUT)
                        aux->aux_error_num = DP_AUX_ERR_TOUT;
                if (isr & DP_INTR_NACK_DEFER)
                        aux->aux_error_num = DP_AUX_ERR_NACK_DEFER;
                if (isr & DP_INTR_I2C_NACK)
                        aux->aux_error_num = DP_AUX_ERR_NACK;
                if (isr & DP_INTR_I2C_DEFER)
                        aux->aux_error_num = DP_AUX_ERR_DEFER;
                if (isr & DP_INTR_AUX_ERROR) {
                        aux->aux_error_num = DP_AUX_ERR_PHY;
                        dp_catalog_aux_clear_hw_interrupts(aux->catalog);
                }
        }
}

static void dp_aux_update_offset_and_segment(struct dp_aux_private *aux,
                                             struct drm_dp_aux_msg *input_msg)
{
        u32 edid_address = 0x50;
        u32 segment_address = 0x30;
        bool i2c_read = input_msg->request &
                (DP_AUX_I2C_READ & DP_AUX_NATIVE_READ);
        u8 *data;

        if (aux->native || i2c_read || ((input_msg->address != edid_address) &&
                (input_msg->address != segment_address)))
                return;


        data = input_msg->buffer;
        if (input_msg->address == segment_address)
                aux->segment = *data;
        else
                aux->offset = *data;
}

/**
 * dp_aux_transfer_helper() - helper function for EDID read transactions
 *
 * @aux: DP AUX private structure
 * @input_msg: input message from DRM upstream APIs
 * @send_seg: send the segment to sink
 *
 * return: void
 *
 * This helper function is used to fix EDID reads for non-compliant
 * sinks that do not handle the i2c middle-of-transaction flag correctly.
 */
static void dp_aux_transfer_helper(struct dp_aux_private *aux,
                                   struct drm_dp_aux_msg *input_msg,
                                   bool send_seg)
{
        struct drm_dp_aux_msg helper_msg;
        u32 message_size = 0x10;
        u32 segment_address = 0x30;
        u32 const edid_block_length = 0x80;
        bool i2c_mot = input_msg->request & DP_AUX_I2C_MOT;
        bool i2c_read = input_msg->request &
                (DP_AUX_I2C_READ & DP_AUX_NATIVE_READ);

        if (!i2c_mot || !i2c_read || (input_msg->size == 0))
                return;

        /*
         * Sending the segment value and EDID offset will be performed
         * from the DRM upstream EDID driver for each block. Avoid
         * duplicate AUX transactions related to this while reading the
         * first 16 bytes of each block.
         */
        if (!(aux->offset % edid_block_length) || !send_seg)
                goto end;

        aux->read = false;
        aux->cmd_busy = true;
        aux->no_send_addr = true;
        aux->no_send_stop = true;

        /*
         * Send the segment address for every i2c read in which the
         * middle-of-tranaction flag is set. This is required to support EDID
         * reads of more than 2 blocks as the segment address is reset to 0
         * since we are overriding the middle-of-transaction flag for read
         * transactions.
         */

        if (aux->segment) {
                memset(&helper_msg, 0, sizeof(helper_msg));
                helper_msg.address = segment_address;
                helper_msg.buffer = &aux->segment;
                helper_msg.size = 1;
                dp_aux_cmd_fifo_tx(aux, &helper_msg);
        }

        /*
         * Send the offset address for every i2c read in which the
         * middle-of-transaction flag is set. This will ensure that the sink
         * will update its read pointer and return the correct portion of the
         * EDID buffer in the subsequent i2c read trasntion triggered in the
         * native AUX transfer function.
         */
        memset(&helper_msg, 0, sizeof(helper_msg));
        helper_msg.address = input_msg->address;
        helper_msg.buffer = &aux->offset;
        helper_msg.size = 1;
        dp_aux_cmd_fifo_tx(aux, &helper_msg);

end:
        aux->offset += message_size;
        if (aux->offset == 0x80 || aux->offset == 0x100)
                aux->segment = 0x0; /* reset segment at end of block */
}

/*
 * This function does the real job to process an AUX transaction.
 * It will call aux_reset() function to reset the AUX channel,
 * if the waiting is timeout.
 */
static ssize_t dp_aux_transfer(struct drm_dp_aux *dp_aux,
                               struct drm_dp_aux_msg *msg)
{
        ssize_t ret;
        int const aux_cmd_native_max = 16;
        int const aux_cmd_i2c_max = 128;
        struct dp_aux_private *aux;

        aux = container_of(dp_aux, struct dp_aux_private, dp_aux);

        aux->native = msg->request & (DP_AUX_NATIVE_WRITE & DP_AUX_NATIVE_READ);

        /* Ignore address only message */
        if (msg->size == 0 || !msg->buffer) {
                msg->reply = aux->native ?
                        DP_AUX_NATIVE_REPLY_ACK : DP_AUX_I2C_REPLY_ACK;
                return msg->size;
        }

        /* msg sanity check */
        if ((aux->native && msg->size > aux_cmd_native_max) ||
            msg->size > aux_cmd_i2c_max) {
                DRM_ERROR("%s: invalid msg: size(%zu), request(%x)\n",
                        __func__, msg->size, msg->request);
                return -EINVAL;
        }

        mutex_lock(&aux->mutex);

        dp_aux_update_offset_and_segment(aux, msg);
        dp_aux_transfer_helper(aux, msg, true);

        aux->read = msg->request & (DP_AUX_I2C_READ & DP_AUX_NATIVE_READ);
        aux->cmd_busy = true;

        if (aux->read) {
                aux->no_send_addr = true;
                aux->no_send_stop = false;
        } else {
                aux->no_send_addr = true;
                aux->no_send_stop = true;
        }

        ret = dp_aux_cmd_fifo_tx(aux, msg);
        if (ret < 0) {
                if (aux->native) {
                        aux->retry_cnt++;
                        if (!(aux->retry_cnt % MAX_AUX_RETRIES))
                                dp_catalog_aux_update_cfg(aux->catalog);
                }
                /* reset aux if link is in connected state */
                if (dp_catalog_link_is_connected(aux->catalog))
                        dp_catalog_aux_reset(aux->catalog);
        } else {
                aux->retry_cnt = 0;
                switch (aux->aux_error_num) {
                case DP_AUX_ERR_NONE:
                        if (aux->read)
                                ret = dp_aux_cmd_fifo_rx(aux, msg);
                        msg->reply = aux->native ? DP_AUX_NATIVE_REPLY_ACK : DP_AUX_I2C_REPLY_ACK;
                        break;
                case DP_AUX_ERR_DEFER:
                        msg->reply = aux->native ? DP_AUX_NATIVE_REPLY_DEFER : DP_AUX_I2C_REPLY_DEFER;
                        break;
                case DP_AUX_ERR_PHY:
                case DP_AUX_ERR_ADDR:
                case DP_AUX_ERR_NACK:
                case DP_AUX_ERR_NACK_DEFER:
                        msg->reply = aux->native ? DP_AUX_NATIVE_REPLY_NACK : DP_AUX_I2C_REPLY_NACK;
                        break;
                case DP_AUX_ERR_TOUT:
                        ret = -ETIMEDOUT;
                        break;
                }
        }

        aux->cmd_busy = false;
        mutex_unlock(&aux->mutex);

        return ret;
}

void dp_aux_isr(struct drm_dp_aux *dp_aux)
{
        u32 isr;
        struct dp_aux_private *aux;

        if (!dp_aux) {
                DRM_ERROR("invalid input\n");
                return;
        }

        aux = container_of(dp_aux, struct dp_aux_private, dp_aux);

        isr = dp_catalog_aux_get_irq(aux->catalog);

        if (!aux->cmd_busy)
                return;

        if (aux->native)
                dp_aux_native_handler(aux, isr);
        else
                dp_aux_i2c_handler(aux, isr);

        complete(&aux->comp);
}

void dp_aux_reconfig(struct drm_dp_aux *dp_aux)
{
        struct dp_aux_private *aux;

        aux = container_of(dp_aux, struct dp_aux_private, dp_aux);

        dp_catalog_aux_update_cfg(aux->catalog);
        dp_catalog_aux_reset(aux->catalog);
}

void dp_aux_init(struct drm_dp_aux *dp_aux)
{
        struct dp_aux_private *aux;

        if (!dp_aux) {
                DRM_ERROR("invalid input\n");
                return;
        }

        aux = container_of(dp_aux, struct dp_aux_private, dp_aux);

        dp_catalog_aux_enable(aux->catalog, true);
        aux->retry_cnt = 0;
}

void dp_aux_deinit(struct drm_dp_aux *dp_aux)
{
        struct dp_aux_private *aux;

        aux = container_of(dp_aux, struct dp_aux_private, dp_aux);

        dp_catalog_aux_enable(aux->catalog, false);
}

int dp_aux_register(struct drm_dp_aux *dp_aux)
{
        struct dp_aux_private *aux;
        int ret;

        if (!dp_aux) {
                DRM_ERROR("invalid input\n");
                return -EINVAL;
        }

        aux = container_of(dp_aux, struct dp_aux_private, dp_aux);

        aux->dp_aux.name = "dpu_dp_aux";
        aux->dp_aux.dev = aux->dev;
        aux->dp_aux.transfer = dp_aux_transfer;
        ret = drm_dp_aux_register(&aux->dp_aux);
        if (ret) {
                DRM_ERROR("%s: failed to register drm aux: %d\n", __func__,
                                ret);
                return ret;
        }

        return 0;
}

void dp_aux_unregister(struct drm_dp_aux *dp_aux)
{
        drm_dp_aux_unregister(dp_aux);
}

struct drm_dp_aux *dp_aux_get(struct device *dev, struct dp_catalog *catalog)
{
        struct dp_aux_private *aux;

        if (!catalog) {
                DRM_ERROR("invalid input\n");
                return ERR_PTR(-ENODEV);
        }

        aux = devm_kzalloc(dev, sizeof(*aux), GFP_KERNEL);
        if (!aux)
                return ERR_PTR(-ENOMEM);

        init_completion(&aux->comp);
        aux->cmd_busy = false;
        mutex_init(&aux->mutex);

        aux->dev = dev;
        aux->catalog = catalog;
        aux->retry_cnt = 0;

        return &aux->dp_aux;
}

void dp_aux_put(struct drm_dp_aux *dp_aux)
{
        struct dp_aux_private *aux;

        if (!dp_aux)
                return;

        aux = container_of(dp_aux, struct dp_aux_private, dp_aux);

        mutex_destroy(&aux->mutex);

        devm_kfree(aux->dev, aux);
}