详解ARM的AMBA设备中的DMA设备PL08X的Linux驱动

第 1 章 ARM的PL08X的代码的详细解析 第一部分

 *
 * (Bursts are irrelevant for mem to mem transfers - there are no burst signals)
 *
 * Details of each tranfer on a particular channel
 * are held in the DMA channel array
 * A workqueue uses those details to initiate the actual transfer
 * The DMAC interrupt clears the relevant transfer in the channel array
 *
 * ASSUMES only one DMAC device exists in the system
 * ASSUMES default (little) endianness for DMA transfers
 *
 * Only DMAC flow control is implemented
 *
 */
#include <linux/device.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/pci.h>
#include <linux/interrupt.h>

#include <linux/workqueue.h>

#include <linux/dmapool.h>
#include <asm/dma.h>
#include <asm/mach/dma.h>
#include <asm/atomic.h>
#include <asm/processor.h>
#include <linux/amba/bus.h>

#include <linux/dmaengine.h>
#include <asm/cacheflush.h>

#include <linux/amba/pl08x.h>
int ctr_chan[2];

/*
 * Predeclare the DMAENGINE API functions
 */
static int	pl08x_alloc_chan_resources(struct dma_chan *chan,
						struct dma_client *client);
static void	pl08x_free_chan_resources(struct dma_chan *chan);
static struct	dma_async_tx_descriptor *pl08x_prep_dma_memcpy(
			struct dma_chan *chan, dma_addr_t dest, dma_addr_t src,
				size_t len, unsigned long flags);
static struct dma_async_tx_descriptor *pl08x_prep_dma_interrupt(
			struct dma_chan *chan, unsigned long flags);
static enum	dma_status pl08x_dma_is_complete(struct dma_chan *chan,
					dma_cookie_t cookie, dma_cookie_t *last,
						dma_cookie_t *used);
static void	pl08x_issue_pending(struct dma_chan *chan);
static struct dma_async_tx_descriptor *pl08x_prep_slave_sg(
		struct dma_chan *chan, struct scatterlist *sgl,
		unsigned int sg_len, enum dma_data_direction direction,
		unsigned long flags);
static void pl08x_terminate_all(struct dma_chan *chan);

struct dma_device dmac = {
	.device_alloc_chan_resources	= pl08x_alloc_chan_resources,
	.device_free_chan_resources	= pl08x_free_chan_resources,
	.device_prep_dma_memcpy		= pl08x_prep_dma_memcpy,
	.device_prep_dma_xor		= NULL,
	.device_prep_dma_zero_sum	= NULL,
	.device_prep_dma_memset		= NULL,
	.device_prep_dma_interrupt	= pl08x_prep_dma_interrupt,
	.device_is_tx_complete		= pl08x_dma_is_complete,
	.device_issue_pending		= pl08x_issue_pending,
	.device_prep_slave_sg		= pl08x_prep_slave_sg,
	.device_terminate_all		= pl08x_terminate_all,
};