// SPDX-License-Identifier: GPL-2.0-only
/*
 * PXA2xx SPI DMA engine support.
 *
 * Copyright (C) 2013, 2021 Intel Corporation
 * Author: Mika Westerberg <mika.westerberg@linux.intel.com>
 */

#include <linux/atomic.h>
#include <linux/dev_printk.h>
#include <linux/dma-mapping.h>
#include <linux/dmaengine.h>
#include <linux/errno.h>
#include <linux/irqreturn.h>
#include <linux/scatterlist.h>
#include <linux/string.h>
#include <linux/types.h>

#include <linux/spi/spi.h>

#include "spi-pxa2xx.h"

struct device;

static void pxa2xx_spi_dma_transfer_complete(struct driver_data *drv_data,
                                             bool error)
{
        struct spi_message *msg = drv_data->controller->cur_msg;

        /*
         * It is possible that one CPU is handling ROR interrupt and other
         * just gets DMA completion. Calling pump_transfers() twice for the
         * same transfer leads to problems thus we prevent concurrent calls
         * by using dma_running.
         */
        if (atomic_dec_and_test(&drv_data->dma_running)) {
                /*
                 * If the other CPU is still handling the ROR interrupt we
                 * might not know about the error yet. So we re-check the
                 * ROR bit here before we clear the status register.
                 */
                if (!error)
                        error = read_SSSR_bits(drv_data, drv_data->mask_sr) & SSSR_ROR;

                /* Clear status & disable interrupts */
                clear_SSCR1_bits(drv_data, drv_data->dma_cr1);
                write_SSSR_CS(drv_data, drv_data->clear_sr);
                if (!pxa25x_ssp_comp(drv_data))
                        pxa2xx_spi_write(drv_data, SSTO, 0);

                if (error) {
                        /* In case we got an error we disable the SSP now */
                        pxa_ssp_disable(drv_data->ssp);
                        msg->status = -EIO;
                }

                spi_finalize_current_transfer(drv_data->controller);
        }
}

static void pxa2xx_spi_dma_callback(void *data)
{
        pxa2xx_spi_dma_transfer_complete(data, false);
}

static struct dma_async_tx_descriptor *
pxa2xx_spi_dma_prepare_one(struct driver_data *drv_data,
                           enum dma_transfer_direction dir,
                           struct spi_transfer *xfer)
{
        enum dma_slave_buswidth width;
        struct dma_slave_config cfg;
        struct dma_chan *chan;
        struct sg_table *sgt;
        int ret;

        switch (drv_data->n_bytes) {
        case 1:
                width = DMA_SLAVE_BUSWIDTH_1_BYTE;
                break;
        case 2:
                width = DMA_SLAVE_BUSWIDTH_2_BYTES;
                break;
        default:
                width = DMA_SLAVE_BUSWIDTH_4_BYTES;
                break;
        }

        memset(&cfg, 0, sizeof(cfg));
        cfg.direction = dir;

        if (dir == DMA_MEM_TO_DEV) {
                cfg.dst_addr = drv_data->ssp->phys_base + SSDR;
                cfg.dst_addr_width = width;
                cfg.dst_maxburst = drv_data->controller_info->dma_burst_size;

                sgt = &xfer->tx_sg;
                chan = drv_data->controller->dma_tx;
        } else {
                cfg.src_addr = drv_data->ssp->phys_base + SSDR;
                cfg.src_addr_width = width;
                cfg.src_maxburst = drv_data->controller_info->dma_burst_size;

                sgt = &xfer->rx_sg;
                chan = drv_data->controller->dma_rx;
        }

        ret = dmaengine_slave_config(chan, &cfg);
        if (ret) {
                dev_warn(drv_data->ssp->dev, "DMA slave config failed\n");
                return NULL;
        }

        return dmaengine_prep_slave_sg(chan, sgt->sgl, sgt->nents, dir,
                                       DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
}

irqreturn_t pxa2xx_spi_dma_transfer(struct driver_data *drv_data)
{
        u32 status;

        status = read_SSSR_bits(drv_data, drv_data->mask_sr);
        if (status & SSSR_ROR) {
                dev_err(drv_data->ssp->dev, "FIFO overrun\n");

                dmaengine_terminate_async(drv_data->controller->dma_rx);
                dmaengine_terminate_async(drv_data->controller->dma_tx);

                pxa2xx_spi_dma_transfer_complete(drv_data, true);
                return IRQ_HANDLED;
        }

        return IRQ_NONE;
}

int pxa2xx_spi_dma_prepare(struct driver_data *drv_data,
                           struct spi_transfer *xfer)
{
        struct dma_async_tx_descriptor *tx_desc, *rx_desc;
        int err;

        tx_desc = pxa2xx_spi_dma_prepare_one(drv_data, DMA_MEM_TO_DEV, xfer);
        if (!tx_desc) {
                dev_err(drv_data->ssp->dev, "failed to get DMA TX descriptor\n");
                err = -EBUSY;
                goto err_tx;
        }

        rx_desc = pxa2xx_spi_dma_prepare_one(drv_data, DMA_DEV_TO_MEM, xfer);
        if (!rx_desc) {
                dev_err(drv_data->ssp->dev, "failed to get DMA RX descriptor\n");
                err = -EBUSY;
                goto err_rx;
        }

        /* We are ready when RX completes */
        rx_desc->callback = pxa2xx_spi_dma_callback;
        rx_desc->callback_param = drv_data;

        dmaengine_submit(rx_desc);
        dmaengine_submit(tx_desc);
        return 0;

err_rx:
        dmaengine_terminate_async(drv_data->controller->dma_tx);
err_tx:
        return err;
}

void pxa2xx_spi_dma_start(struct driver_data *drv_data)
{
        dma_async_issue_pending(drv_data->controller->dma_rx);
        dma_async_issue_pending(drv_data->controller->dma_tx);

        atomic_set(&drv_data->dma_running, 1);
}

void pxa2xx_spi_dma_stop(struct driver_data *drv_data)
{
        atomic_set(&drv_data->dma_running, 0);
        dmaengine_terminate_sync(drv_data->controller->dma_rx);
        dmaengine_terminate_sync(drv_data->controller->dma_tx);
}

int pxa2xx_spi_dma_setup(struct driver_data *drv_data)
{
        struct pxa2xx_spi_controller *pdata = drv_data->controller_info;
        struct spi_controller *controller = drv_data->controller;
        struct device *dev = drv_data->ssp->dev;
        dma_cap_mask_t mask;

        dma_cap_zero(mask);
        dma_cap_set(DMA_SLAVE, mask);

        controller->dma_tx = dma_request_slave_channel_compat(mask,
                                pdata->dma_filter, pdata->tx_param, dev, "tx");
        if (!controller->dma_tx)
                return -ENODEV;

        controller->dma_rx = dma_request_slave_channel_compat(mask,
                                pdata->dma_filter, pdata->rx_param, dev, "rx");
        if (!controller->dma_rx) {
                dma_release_channel(controller->dma_tx);
                controller->dma_tx = NULL;
                return -ENODEV;
        }

        return 0;
}

void pxa2xx_spi_dma_release(struct driver_data *drv_data)
{
        struct spi_controller *controller = drv_data->controller;

        if (controller->dma_rx) {
                dmaengine_terminate_sync(controller->dma_rx);
                dma_release_channel(controller->dma_rx);
                controller->dma_rx = NULL;
        }
        if (controller->dma_tx) {
                dmaengine_terminate_sync(controller->dma_tx);
                dma_release_channel(controller->dma_tx);
                controller->dma_tx = NULL;
        }
}