path: root/drivers/dma/sh/shdma-base.c

/*
 * Dmaengine driver base library for DMA controllers, found on SH-based SoCs
 *
 * extracted from shdma.c
 *
 * Copyright (C) 2011-2012 Guennadi Liakhovetski <g.liakhovetski@gmx.de>
 * Copyright (C) 2009 Nobuhiro Iwamatsu <iwamatsu.nobuhiro@renesas.com>
 * Copyright (C) 2009 Renesas Solutions, Inc. All rights reserved.
 * Copyright (C) 2007 Freescale Semiconductor, Inc. All rights reserved.
 *
 * This is free software; you can redistribute it and/or modify
 * it under the terms of version 2 of the GNU General Public License as
 * published by the Free Software Foundation.
 */

#include <linux/delay.h>
#include <linux/shdma-base.h>
#include <linux/dmaengine.h>
#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/module.h>
#include <linux/pm_runtime.h>
#include <linux/slab.h>
#include <linux/spinlock.h>

#include "../dmaengine.h"

/* DMA descriptor control */
enum shdma_desc_status {
	DESC_IDLE,
	DESC_PREPARED,
	DESC_SUBMITTED,
	DESC_COMPLETED,	/* completed, have to call callback */
	DESC_WAITING,	/* callback called, waiting for ack / re-submit */
};

#define NR_DESCS_PER_CHANNEL 32

#define to_shdma_chan(c) container_of(c, struct shdma_chan, dma_chan)
#define to_shdma_dev(d) container_of(d, struct shdma_dev, dma_dev)

/*
 * For slave DMA we assume, that there is a finite number of DMA slaves in the
 * system, and that each such slave can only use a finite number of channels.
 * We use slave channel IDs to make sure, that no such slave channel ID is
 * allocated more than once.
 */
static unsigned int slave_num = 256;
module_param(slave_num, uint, 0444);

/* A bitmask with slave_num bits */
static unsigned long *shdma_slave_used;

/* Called under spin_lock_irq(&schan->chan_lock") */
static void shdma_chan_xfer_ld_queue(struct shdma_chan *schan)
{
	struct shdma_dev *sdev = to_shdma_dev(schan->dma_chan.device);
	const struct shdma_ops *ops = sdev->ops;
	struct shdma_desc *sdesc;

	/* DMA work check */
	if (ops->channel_busy(schan))
		return;

	/* Find the first not transferred descriptor */
	list_for_each_entry(sdesc, &schan->ld_queue, node)
		if (sdesc->mark == DESC_SUBMITTED) {
			ops->start_xfer(schan, sdesc);
			break;
		}
}

static dma_cookie_t shdma_tx_submit(struct dma_async_tx_descriptor *tx)
{
	struct shdma_desc *chunk, *c, *desc =
		container_of(tx, struct shdma_desc, async_tx);
	struct shdma_chan *schan = to_shdma_chan(tx->chan);
	dma_async_tx_callback callback = tx->callback;
	dma_cookie_t cookie;
	bool power_up;

	spin_lock_irq(&schan->chan_lock);

	power_up = list_empty(&schan->ld_queue);

	cookie = dma_cookie_assign(tx);

	/* Mark all chunks of this descriptor as submitted, move to the queue */
	list_for_each_entry_safe(chunk, c, desc->node.prev, node) {
		/*
		 * All chunks are on the global ld_free, so, we have to find
		 * the end of the chain ourselves
		 */
		if (chunk != desc && (chunk->mark == DESC_IDLE ||
				      chunk->async_tx.cookie > 0 ||
				      chunk->async_tx.cookie == -EBUSY ||
				      &chunk->node == &schan->ld_free))
			break;
		chunk->mark = DESC_SUBMITTED;
		if (chunk->chunks == 1) {
			chunk->async_tx.callback = callback;
			chunk->async_tx.callback_param = tx->callback_param;
		} else {
			/* Callback goes to the last chunk */
			chunk->async_tx.callback = NULL;
		}
		chunk->cookie = cookie;
		list_move_tail(&chunk->node, &schan->ld_queue);

		dev_dbg(schan->dev, "submit #%d@%p on %d\n",
			tx->cookie, &chunk->async_tx, schan->id);
	}

	if (power_up) {
		int ret;
		schan->pm_state = SHDMA_PM_BUSY;

		ret = pm_runtime_get(schan->dev);

		spin_unlock_irq(&schan->chan_lock);
		if (ret < 0)
			dev_err(schan->dev, "%s(): GET = %d\n", __func__, ret);

		pm_runtime_barrier(schan->dev);

		spin_lock_irq(&schan->chan_lock);

		/* Have we been reset, while waiting? */
		if (schan->pm_state != SHDMA_PM_ESTABLISHED) {
			struct shdma_dev *sdev =
				to_shdma_dev(schan->dma_chan.device);
			const struct shdma_ops *ops = sdev->ops;
			dev_dbg(schan->dev, "Bring up channel %d\n",
				schan->id);
			/*
			 * TODO: .xfer_setup() might fail on some platforms.
			 * Make it int then, on error remove chunks from the
			 * queue again
			 */
			ops->setup_xfer(schan, schan->slave_id);

			if (schan->pm_state == SHDMA_PM_PENDING)
				shdma_chan_xfer_ld_queue(schan);
			schan->pm_state = SHDMA_PM_ESTABLISHED;
		}
	} else {
		/*
		 * Tell .device_issue_pending() not to run the queue, interrupts
		 * will do it anyway
		 */
		schan->pm_state = SHDMA_PM_PENDING;
	}

	spin_unlock_irq(&schan->chan_lock);

	return cookie;
}

/* Called with desc_lock held */
static struct shdma_desc *shdma_get_desc(struct shdma_chan *schan)
{
	struct shdma_desc *sdesc;

	list_for_each_entry(sdesc, &schan->ld_free, node)
		if (sdesc->mark != DESC_PREPARED) {
			BUG_ON(sdesc->mark != DESC_IDLE);
			list_del(&sdesc->node);
			return sdesc;
		}

	return NULL;
}

static int shdma_setup_slave(struct shdma_chan *schan, dma_addr_t slave_addr)
{
	struct shdma_dev *sdev = to_shdma_dev(schan->dma_chan.device);
	const struct shdma_ops *ops = sdev->ops;