drivers/i2c/busses/i2c-stm32.c

Source file repositories/reference/linux-study-clean/drivers/i2c/busses/i2c-stm32.c

File Facts

System
Linux kernel
Corpus path
drivers/i2c/busses/i2c-stm32.c
Extension
.c
Size
3741 bytes
Lines
154
Domain
Driver Families
Bucket
drivers/i2c
Inferred role
Driver Families: implementation source
Status
source implementation candidate

Why This File Exists

Repeatable hardware-adapter layer. Deep compatibility for every driver is out of scope; this atlas records patterns, probe lifecycles, bus glue, IRQ/DMA usage, and links back to core abstractions.

Dependency Surface

Detected Declarations

Annotated Snippet

// 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_probe(dev, ret, "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_probe(dev, ret, "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;

Annotation

Implementation Notes