Quelle  dma-pvr2.c   Sprache: C

// SPDX-License-Identifier: GPL-2.0
/*
 * arch/sh/drivers/dma/dma-pvr2.c
 *
 * NEC PowerVR 2 (Dreamcast) DMA support
 *
 * Copyright (C) 2003, 2004  Paul Mundt
 */
#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 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)
{
 if (request_irq(HW_EVENT_PVR2_DMA, pvr2_dma_interrupt, 0,
   "pvr2 DMA handler", NULL))
  pr_err("Failed to register pvr2 DMA handler interrupt\n");
 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 ");
MODULE_DESCRIPTION("NEC PowerVR 2 DMA driver");
MODULE_LICENSE("GPL v2");