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/*
* i2c-stm32.c
*
* Copyright (C) M'boumba Cedric Madianga 2017
* Author: M'boumba Cedric Madianga <cedric.madianga@gmail.com>
*
* License terms: GNU General Public License (GPL), version 2
*/
#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 NULL;
/* Request and configure I2C TX dma channel */
dma->chan_tx = dma_request_slave_channel(dev, "tx");
if (!dma->chan_tx) {
dev_dbg(dev, "can't request DMA tx channel\n");
ret = -EINVAL;
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_slave_channel(dev, "rx");
if (!dma->chan_rx) {
dev_err(dev, "can't request DMA rx channel\n");
ret = -EINVAL;
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);
dev_info(dev, "can't use DMA\n");
return NULL;
}
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;
struct device *chan_dev;
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;
chan_dev = dma->chan_using->device->dev;
dma->dma_buf = dma_map_single(chan_dev, buf, dma->dma_len,
dma->dma_data_dir);
if (dma_mapping_error(chan_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(chan_dev, dma->dma_buf, dma->dma_len,
dma->dma_data_dir);
return ret;
}
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