drivers/dma/dw/of.c

Source file repositories/reference/linux-study-clean/drivers/dma/dw/of.c

File Facts

System
Linux kernel
Corpus path
drivers/dma/dw/of.c
Extension
.c
Size
3407 bytes
Lines
123
Domain
Driver Families
Bucket
drivers/dma
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
/*
 * Platform driver for the Synopsys DesignWare DMA Controller
 *
 * Copyright (C) 2007-2008 Atmel Corporation
 * Copyright (C) 2010-2011 ST Microelectronics
 * Copyright (C) 2013 Intel Corporation
 */

#include <linux/of.h>
#include <linux/of_dma.h>
#include <linux/platform_device.h>

#include "internal.h"

static struct dma_chan *dw_dma_of_xlate(struct of_phandle_args *dma_spec,
					struct of_dma *ofdma)
{
	struct dw_dma *dw = ofdma->of_dma_data;
	struct dw_dma_slave slave = {
		.dma_dev = dw->dma.dev,
	};
	dma_cap_mask_t cap;

	if (dma_spec->args_count < 3 || dma_spec->args_count > 4)
		return NULL;

	slave.src_id = dma_spec->args[0];
	slave.dst_id = dma_spec->args[0];
	slave.m_master = dma_spec->args[1];
	slave.p_master = dma_spec->args[2];
	if (dma_spec->args_count >= 4)
		slave.channels = dma_spec->args[3];

	if (WARN_ON(slave.src_id >= DW_DMA_MAX_NR_REQUESTS ||
		    slave.dst_id >= DW_DMA_MAX_NR_REQUESTS ||
		    slave.m_master >= dw->pdata->nr_masters ||
		    slave.p_master >= dw->pdata->nr_masters ||
		    slave.channels >= BIT(dw->pdata->nr_channels)))
		return NULL;

	dma_cap_zero(cap);
	dma_cap_set(DMA_SLAVE, cap);

	/* TODO: there should be a simpler way to do this */
	return dma_request_channel(cap, dw_dma_filter, &slave);
}

struct dw_dma_platform_data *dw_dma_parse_dt(struct platform_device *pdev)
{
	struct device_node *np = pdev->dev.of_node;
	struct dw_dma_platform_data *pdata;
	u32 tmp, arr[DW_DMA_MAX_NR_MASTERS];
	u32 nr_masters;
	u32 nr_channels;

	if (of_property_read_u32(np, "dma-masters", &nr_masters))
		return NULL;
	if (nr_masters < 1 || nr_masters > DW_DMA_MAX_NR_MASTERS)
		return NULL;

	if (of_property_read_u32(np, "dma-channels", &nr_channels))
		return NULL;
	if (nr_channels > DW_DMA_MAX_NR_CHANNELS)
		return NULL;

	pdata = devm_kzalloc(&pdev->dev, sizeof(*pdata), GFP_KERNEL);
	if (!pdata)
		return NULL;

	pdata->nr_masters = nr_masters;
	pdata->nr_channels = nr_channels;

	of_property_read_u32(np, "chan_allocation_order", &pdata->chan_allocation_order);
	of_property_read_u32(np, "chan_priority", &pdata->chan_priority);

	of_property_read_u32(np, "block_size", &pdata->block_size);

	/* Try deprecated property first */
	if (!of_property_read_u32_array(np, "data_width", arr, nr_masters)) {
		for (tmp = 0; tmp < nr_masters; tmp++)
			pdata->data_width[tmp] = BIT(arr[tmp] & 0x07);
	}

	/* If "data_width" and "data-width" both provided use the latter one */
	of_property_read_u32_array(np, "data-width", pdata->data_width, nr_masters);

	memset32(pdata->multi_block, 1, nr_channels);
	of_property_read_u32_array(np, "multi-block", pdata->multi_block, nr_channels);

Annotation

Implementation Notes