path: root/drivers/dma/pl330.c

/* linux/drivers/dma/pl330.c
 *
 * Copyright (C) 2010 Samsung Electronics Co. Ltd.
 *	Jaswinder Singh <jassi.brar@samsung.com>
 *
 * 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.
 */

#include <linux/io.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/module.h>
#include <linux/dmaengine.h>
#include <linux/interrupt.h>
#include <linux/amba/bus.h>
#include <linux/amba/pl330.h>
#include <linux/pm_runtime.h>
#include <linux/scatterlist.h>
#include <linux/of.h>

#define NR_DEFAULT_DESC	16

enum desc_status {
	/* In the DMAC pool */
	FREE,
	/*
	 * Allocted to some channel during prep_xxx
	 * Also may be sitting on the work_list.
	 */
	PREP,
	/*
	 * Sitting on the work_list and already submitted
	 * to the PL330 core. Not more than two descriptors
	 * of a channel can be BUSY at any time.
	 */
	BUSY,
	/*
	 * Sitting on the channel work_list but xfer done
	 * by PL330 core
	 */
	DONE,
};

struct dma_pl330_chan {
	/* Schedule desc completion */
	struct tasklet_struct task;

	/* DMA-Engine Channel */
	struct dma_chan chan;

	/* Last completed cookie */
	dma_cookie_t completed;

	/* List of to be xfered descriptors */
	struct list_head work_list;

	/* Pointer to the DMAC that manages this channel,
	 * NULL if the channel is available to be acquired.
	 * As the parent, this DMAC also provides descriptors
	 * to the channel.
	 */
	struct dma_pl330_dmac *dmac;

	/* To protect channel manipulation */
	spinlock_t lock;

	/* Token of a hardware channel thread of PL330 DMAC
	 * NULL if the channel is available to be acquired.
	 */
	void *pl330_chid;

	/* For D-to-M and M-to-D channels */
	int burst_sz; /* the peripheral fifo width */
	int burst_len; /* the number of burst */
	dma_addr_t fifo_addr;

	/* for cyclic capability */
	bool cyclic;
};

struct dma_pl330_dmac {
	struct pl330_info pif;

	/* DMA-Engine Device */
	struct dma_device ddma;

	/* Pool of descriptors available for the DMAC's channels */
	struct list_head desc_pool;
	/* To protect desc_pool manipulation */
	spinlock_t pool_lock;

	/* Peripheral channels connected to this DMAC */
	struct dma_pl330_chan *peripherals; /* keep at end */

	struct clk *clk;
};

struct dma_pl330_desc {
	/* To attach to a queue as child */
	struct list_head node;

	/* Descriptor for the DMA Engine API */
	struct dma_async_tx_descriptor txd;

	/* Xfer for PL330 core */
	struct pl330_xfer px;

	struct pl330_reqcfg rqcfg;
	struct pl330_req req;

	enum desc_status status;

	/* The channel which currently holds this desc */
	struct dma_pl330_chan *pchan;
};

/* forward declaration */
static struct amba_driver pl330_driver;

static inline struct dma_pl330_chan *
to_pchan(struct dma_chan *ch)
{
	if (!ch)
		return NULL;

	return container_of(ch, struct dma_pl330_chan, chan);
}

static inline struct dma_pl330_desc *
to_desc(struct dma_async_tx_descriptor *tx)
{
	return container_of(tx, struct dma_pl330_desc, txd);
}

static inline void free_desc_list(struct list_head *list)
{
	struct dma_pl330_dmac *pdmac;
	struct dma_pl330_desc *desc;
	struct dma_pl330_chan *pch;
	unsigned long flags;

	if (list_empty(list))
		return;

	/* Finish off the work list */
	list_for_each_entry(desc, list, node) {
		dma_async_tx_callback callback;
		void *param;

		/* All desc in a list belong to same channel */
		pch = desc->pchan;
		callback = desc->txd.callback;
		param = desc->txd.callback_param;

		if (callback)
			callback(param);

		desc->pchan = NULL;
	}

	pdmac = pch->dmac;

	spin_lock_irqsave(&pdmac->pool_lock, flags);
	list_splice_tail_init(list, &pdmac->desc_pool);
	spin_unlock_irqrestore(&pdmac->pool_lock, flags);
}

static inline void handle_cyclic_desc_list(struct list_head *list)
{
	struct dma_pl330_desc *desc;
	struct dma_pl330_chan *pch;
	unsigned long flags;

	if (list_empty(list))
		return;

	list_for_each_entry(desc, list, node) {
		dma_async_tx_callback callback;

		/* Change status to reload it */
		desc->status = PREP;
		pch = desc->pchan;
		callback = desc->txd.callback;
		if (callback)
			callback(desc->txd.callback_param);
	}

	spin_lock_irqsave(&pch->lock, flags);
	list_splice_tail_init(list, &pch->work_list);
	spin_unlock_irqrestore(&pch->lock, flags);
}