path: root/drivers/dma/edma.c

/*
 * TI EDMA DMA engine driver
 *
 * Copyright 2012 Texas Instruments
 *
 * 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 version 2.
 *
 * This program is distributed "as is" WITHOUT ANY WARRANTY of any
 * kind, whether express or implied; without even the implied warranty
 * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 */

#include <linux/dmaengine.h>
#include <linux/dma-mapping.h>
#include <linux/err.h>
#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/list.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/slab.h>
#include <linux/spinlock.h>

#include <linux/platform_data/edma.h>

#include "dmaengine.h"
#include "virt-dma.h"

/*
 * This will go away when the private EDMA API is folded
 * into this driver and the platform device(s) are
 * instantiated in the arch code. We can only get away
 * with this simplification because DA8XX may not be built
 * in the same kernel image with other DaVinci parts. This
 * avoids having to sprinkle dmaengine driver platform devices
 * and data throughout all the existing board files.
 */
#ifdef CONFIG_ARCH_DAVINCI_DA8XX
#define EDMA_CTLRS	2
#define EDMA_CHANS	32
#else
#define EDMA_CTLRS	1
#define EDMA_CHANS	64
#endif /* CONFIG_ARCH_DAVINCI_DA8XX */

/*
 * Max of 20 segments per channel to conserve PaRAM slots
 * Also note that MAX_NR_SG should be atleast the no.of periods
 * that are required for ASoC, otherwise DMA prep calls will
 * fail. Today davinci-pcm is the only user of this driver and
 * requires atleast 17 slots, so we setup the default to 20.
 */
#define MAX_NR_SG		20
#define EDMA_MAX_SLOTS		MAX_NR_SG
#define EDMA_DESCRIPTORS	16

struct edma_pset {
	u32				len;
	dma_addr_t			addr;
	struct edmacc_param		param;
};

struct edma_desc {
	struct virt_dma_desc		vdesc;
	struct list_head		node;
	enum dma_transfer_direction	direction;
	int				cyclic;
	int				absync;
	int				pset_nr;
	struct edma_chan		*echan;
	int				processed;

	/*
	 * The following 4 elements are used for residue accounting.
	 *
	 * - processed_stat: the number of SG elements we have traversed
	 * so far to cover accounting. This is updated directly to processed
	 * during edma_callback and is always <= processed, because processed
	 * refers to the number of pending transfer (programmed to EDMA
	 * controller), where as processed_stat tracks number of transfers
	 * accounted for so far.
	 *
	 * - residue: The amount of bytes we have left to transfer for this desc
	 *
	 * - residue_stat: The residue in bytes of data we have covered
	 * so far for accounting. This is updated directly to residue
	 * during callbacks to keep it current.
	 *
	 * - sg_len: Tracks the length of the current intermediate transfer,
	 * this is required to update the residue during intermediate transfer
	 * completion callback.
	 */
	int				processed_stat;
	u32				sg_len;
	u32				residue;
	u32				residue_stat;

	struct edma_pset		pset[0];
};

struct edma_cc;

struct edma_chan {
	struct virt_dma_chan		vchan;
	struct list_head		node;
	struct edma_desc		*edesc;
	struct edma_cc			*ecc;
	int				ch_num;
	bool				alloced;
	int				slot[EDMA_MAX_SLOTS];
	int				missed;
	struct dma_slave_config		cfg;
};

struct edma_cc {
	int				ctlr;
	struct dma_device		dma_slave;
	struct edma_chan		slave_chans[EDMA_CHANS];
	int				num_slave_chans;
	int				dummy_slot;
};

static inline struct edma_cc *to_edma_cc(struct dma_device *d)
{
	return container_of(d, struct edma_cc, dma_slave);
}

static inline struct edma_chan *to_edma_chan(struct dma_chan *c)
{
	return container_of(c, struct edma_chan, vchan.chan);
}

static inline struct edma_desc
*to_edma_desc(struct dma_async_tx_descriptor *tx)
{
	return container_of(tx, struct edma_desc, vdesc.tx);
}

static void edma_desc_free(struct virt_dma_desc *vdesc)
{
	kfree(container_of(vdesc, struct edma_desc, vdesc));
}

/* Dispatch a queued descriptor to the controller (caller holds lock) */
static void edma_execute(struct edma_chan *echan)
{
	struct virt_dma_desc *vdesc;
	struct edma_desc *edesc;
	struct device *dev = echan->vchan.chan.device->dev;
	int i, j, left, nslots;

	/* If either we processed all psets or we're still not started */
	if (!echan->edesc ||
	    echan->edesc->pset_nr == echan->edesc->processed) {
		/* Get next vdesc */
		vdesc = vchan_next_desc(&echan->vchan);
		if (!vdesc) {
			echan->edesc = NULL;
			return;
		}