/*
* Driver for the Atmel AHB DMA Controller (aka HDMA or DMAC on AT91 systems)
*
* Copyright (C) 2008 Atmel Corporation
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
*
* This supports the Atmel AHB DMA Controller,
*
* The driver has currently been tested with the Atmel AT91SAM9RL
* and AT91SAM9G45 series.
*/
#include <linux/clk.h>
#include <linux/dmaengine.h>
#include <linux/dma-mapping.h>
#include <linux/dmapool.h>
#include <linux/interrupt.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/slab.h>
#include "at_hdmac_regs.h"
/*
* Glossary
* --------
*
* at_hdmac : Name of the ATmel AHB DMA Controller
* at_dma_ / atdma : ATmel DMA controller entity related
* atc_ / atchan : ATmel DMA Channel entity related
*/
#define ATC_DEFAULT_CFG (ATC_FIFOCFG_HALFFIFO)
#define ATC_DEFAULT_CTRLA (0)
#define ATC_DEFAULT_CTRLB (ATC_SIF(0) \
|ATC_DIF(1))
/*
* Initial number of descriptors to allocate for each channel. This could
* be increased during dma usage.
*/
static unsigned int init_nr_desc_per_channel = 64;
module_param(init_nr_desc_per_channel, uint, 0644);
MODULE_PARM_DESC(init_nr_desc_per_channel,
"initial descriptors per channel (default: 64)");
/* prototypes */
static dma_cookie_t atc_tx_submit(struct dma_async_tx_descriptor *tx);
/*----------------------------------------------------------------------*/
static struct at_desc *atc_first_active(struct at_dma_chan *atchan)
{
return list_first_entry(&atchan->active_list,
struct at_desc, desc_node);
}
static struct at_desc *atc_first_queued(struct at_dma_chan *atchan)
{
return list_first_entry(&atchan->queue,
struct at_desc, desc_node);
}
/**
* atc_alloc_descriptor - allocate and return an initialized descriptor
* @chan: the channel to allocate descriptors for
* @gfp_flags: GFP allocation flags
*
* Note: The ack-bit is positioned in the descriptor flag at creation time
* to make initial allocation more convenient. This bit will be cleared
* and control will be given to client at usage time (during
* preparation functions).
*/
static struct at_desc *atc_alloc_descriptor(struct dma_chan *chan,
gfp_t gfp_flags)
{
struct at_desc *desc = NULL;
struct at_dma *atdma = to_at_dma(chan->device);
dma_addr_t phys;
desc = dma_pool_alloc(atdma->dma_desc_pool, gfp_flags, &phys);
if (desc) {
memset(desc, 0, sizeof(struct at_desc));
INIT_LIST_HEAD(&desc->tx_list);
dma_async_tx_descriptor_init(&desc->txd, chan);
/* txd.flags will be overwritten in prep functions */
desc->txd.flags = DMA_CTRL_ACK;
desc->txd.tx_submit = atc_tx_submit;
desc->txd.phys = phys;
}
return desc;
}
/**
* atc_desc_get - get an unused descriptor from free_list
* @atchan: channel we want a new descriptor for
*/
static struct at_desc *atc_desc_get(struct at_dma_chan *atchan)
{
struct at_desc *desc, *_desc;
struct at_desc *ret = NULL;
unsigned int i = 0;
LIST_HEAD(tmp_list);
spin_lock_bh(&atchan->lock);
list_for_each_entry_safe(desc, _desc, &atchan->free_list, desc_node) {
i++;
if (async_tx_test_ack(&desc->txd)) {
list_del(&desc->desc_node);
ret = desc;
break;
}
dev_dbg(chan2dev(&atchan->chan_common),
"desc %p not ACKed\n"