// SPDX-License-Identifier: GPL-2.0-only
/*
 * i2c-stm32.c
 *
 * Copyright (C) M'boumba Cedric Madianga 2017
 * Author: M'boumba Cedric Madianga <cedric.madianga@gmail.com>
 */

#include "i2c-stm32.h"

/* Functions for DMA support */
struct stm32_i2c_dma *stm32_i2c_dma_request(struct device *dev,
                                            dma_addr_t phy_addr,
                                            u32 txdr_offset,
                                            u32 rxdr_offset)
{
        struct stm32_i2c_dma *dma;
        struct dma_slave_config dma_sconfig;
        int ret;

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

        /* Request and configure I2C TX dma channel */
        dma->chan_tx = dma_request_chan(dev, "tx");
        if (IS_ERR(dma->chan_tx)) {
                ret = PTR_ERR(dma->chan_tx);
                if (ret != -ENODEV)
                        dev_err_probe(dev, ret, "can't request DMA tx channel\n");

                goto fail_al;
        }

        memset(&dma_sconfig, 0, sizeof(dma_sconfig));
        dma_sconfig.dst_addr = phy_addr + txdr_offset;
        dma_sconfig.dst_addr_width = DMA_SLAVE_BUSWIDTH_1_BYTE;
        dma_sconfig.dst_maxburst = 1;
        dma_sconfig.direction = DMA_MEM_TO_DEV;
        ret = dmaengine_slave_config(dma->chan_tx, &dma_sconfig);
        if (ret < 0) {
                dev_err(dev, "can't configure tx channel\n");
                goto fail_tx;
        }

        /* Request and configure I2C RX dma channel */
        dma->chan_rx = dma_request_chan(dev, "rx");
        if (IS_ERR(dma->chan_rx)) {
                ret = PTR_ERR(dma->chan_rx);
                if (ret != -ENODEV)
                        dev_err_probe(dev, ret, "can't request DMA rx channel\n");

                goto fail_tx;
        }

        memset(&dma_sconfig, 0, sizeof(dma_sconfig));
        dma_sconfig.src_addr = phy_addr + rxdr_offset;
        dma_sconfig.src_addr_width = DMA_SLAVE_BUSWIDTH_1_BYTE;
        dma_sconfig.src_maxburst = 1;
        dma_sconfig.direction = DMA_DEV_TO_MEM;
        ret = dmaengine_slave_config(dma->chan_rx, &dma_sconfig);
        if (ret < 0) {
                dev_err(dev, "can't configure rx channel\n");
                goto fail_rx;
        }

        init_completion(&dma->dma_complete);

        dev_info(dev, "using %s (tx) and %s (rx) for DMA transfers\n",
                 dma_chan_name(dma->chan_tx), dma_chan_name(dma->chan_rx));

        return dma;

fail_rx:
        dma_release_channel(dma->chan_rx);
fail_tx:
        dma_release_channel(dma->chan_tx);
fail_al:
        devm_kfree(dev, dma);

        return ERR_PTR(ret);
}

void stm32_i2c_dma_free(struct stm32_i2c_dma *dma)
{
        dma->dma_buf = 0;
        dma->dma_len = 0;

        dma_release_channel(dma->chan_tx);
        dma->chan_tx = NULL;

        dma_release_channel(dma->chan_rx);
        dma->chan_rx = NULL;

        dma->chan_using = NULL;
}

int stm32_i2c_prep_dma_xfer(struct device *dev, struct stm32_i2c_dma *dma,
                            bool rd_wr, u32 len, u8 *buf,
                            dma_async_tx_callback callback,
                            void *dma_async_param)
{
        struct dma_async_tx_descriptor *txdesc;
        int ret;

        if (rd_wr) {
                dma->chan_using = dma->chan_rx;
                dma->dma_transfer_dir = DMA_DEV_TO_MEM;
                dma->dma_data_dir = DMA_FROM_DEVICE;
        } else {
                dma->chan_using = dma->chan_tx;
                dma->dma_transfer_dir = DMA_MEM_TO_DEV;
                dma->dma_data_dir = DMA_TO_DEVICE;
        }

        dma->dma_len = len;

        dma->dma_buf = dma_map_single(dev, buf, dma->dma_len,
                                      dma->dma_data_dir);
        if (dma_mapping_error(dev, dma->dma_buf)) {
                dev_err(dev, "DMA mapping failed\n");
                return -EINVAL;
        }

        txdesc = dmaengine_prep_slave_single(dma->chan_using, dma->dma_buf,
                                             dma->dma_len,
                                             dma->dma_transfer_dir,
                                             DMA_PREP_INTERRUPT);
        if (!txdesc) {
                dev_err(dev, "Not able to get desc for DMA xfer\n");
                ret = -EINVAL;
                goto err;
        }

        reinit_completion(&dma->dma_complete);

        txdesc->callback = callback;
        txdesc->callback_param = dma_async_param;
        ret = dma_submit_error(dmaengine_submit(txdesc));
        if (ret < 0) {
                dev_err(dev, "DMA submit failed\n");
                goto err;
        }

        dma_async_issue_pending(dma->chan_using);

        return 0;

err:
        dma_unmap_single(dev, dma->dma_buf, dma->dma_len,
                         dma->dma_data_dir);
        return ret;
}