dma-pvr2.c

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/*
 * arch/sh/drivers/dma/dma-pvr2.c
 *
 * NEC PowerVR 2 (Dreamcast) DMA support
 *
 * Copyright (C) 2003, 2004  Paul Mundt
 *
 * This file is subject to the terms and conditions of the GNU General Public
 * License.  See the file "COPYING" in the main directory of this archive
 * for more details.
 */
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/interrupt.h>
#include <mach/sysasic.h>
#include <mach/dma.h>
#include <asm/dma.h>
#include <asm/io.h>

static unsigned int xfer_complete;
static int count;

static irqreturn_t pvr2_dma_interrupt(int irq, void *dev_id)
{
    if (get_dma_residue(PVR2_CASCADE_CHAN)) {
        printk(KERN_WARNING "DMA: SH DMAC did not complete transfer "
               "on channel %d, waiting..\n", PVR2_CASCADE_CHAN);
        dma_wait_for_completion(PVR2_CASCADE_CHAN);
    }

    if (count++ < 10)
        pr_debug("Got a pvr2 dma interrupt for channel %d\n",
             irq - HW_EVENT_PVR2_DMA);

    xfer_complete = 1;

    return IRQ_HANDLED;
}

static int pvr2_request_dma(struct dma_channel *chan)
{
    if (__raw_readl(PVR2_DMA_MODE) != 0)
        return -EBUSY;

    __raw_writel(0, PVR2_DMA_LMMODE0);

    return 0;
}

static int pvr2_get_dma_residue(struct dma_channel *chan)
{
    return xfer_complete == 0;
}

static int pvr2_xfer_dma(struct dma_channel *chan)
{
    if (chan->sar || !chan->dar)
        return -EINVAL;

    xfer_complete = 0;

    __raw_writel(chan->dar, PVR2_DMA_ADDR);
    __raw_writel(chan->count, PVR2_DMA_COUNT);
    __raw_writel(chan->mode & DMA_MODE_MASK, PVR2_DMA_MODE);

    return 0;
}

static struct irqaction pvr2_dma_irq = {
    .name       = "pvr2 DMA handler",
    .handler    = pvr2_dma_interrupt,
};

static struct dma_ops pvr2_dma_ops = {
    .request    = pvr2_request_dma,
    .get_residue    = pvr2_get_dma_residue,
    .xfer       = pvr2_xfer_dma,
};

static struct dma_info pvr2_dma_info = {
    .name       = "pvr2_dmac",
    .nr_channels    = 1,
    .ops        = &pvr2_dma_ops,
    .flags      = DMAC_CHANNELS_TEI_CAPABLE,
};

static int __init pvr2_dma_init(void)
{
    setup_irq(HW_EVENT_PVR2_DMA, &pvr2_dma_irq);
    request_dma(PVR2_CASCADE_CHAN, "pvr2 cascade");

    return register_dmac(&pvr2_dma_info);
}

static void __exit pvr2_dma_exit(void)
{
    free_dma(PVR2_CASCADE_CHAN);
    free_irq(HW_EVENT_PVR2_DMA, 0);
    unregister_dmac(&pvr2_dma_info);
}

subsys_initcall(pvr2_dma_init);
module_exit(pvr2_dma_exit);

MODULE_AUTHOR("Paul Mundt <[email protected]>");
MODULE_DESCRIPTION("NEC PowerVR 2 DMA driver");
MODULE_LICENSE("GPL");