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torvalds
GitHub Repository: torvalds/linux
 Path: blob/master/arch/sh/drivers/dma/dma-pvr2.c
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// SPDX-License-Identifier: GPL-2.0

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/*

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 * arch/sh/drivers/dma/dma-pvr2.c

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 *

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 * NEC PowerVR 2 (Dreamcast) DMA support

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 *

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 * Copyright (C) 2003, 2004  Paul Mundt

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 */

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#include <linux/init.h>

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#include <linux/kernel.h>

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#include <linux/module.h>

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#include <linux/interrupt.h>

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#include <mach/sysasic.h>

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#include <mach/dma.h>

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#include <asm/dma.h>

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#include <asm/io.h>

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static unsigned int xfer_complete;

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static int count;

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static irqreturn_t pvr2_dma_interrupt(int irq, void *dev_id)

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{

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	if (get_dma_residue(PVR2_CASCADE_CHAN)) {

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		printk(KERN_WARNING "DMA: SH DMAC did not complete transfer "

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		       "on channel %d, waiting..\n", PVR2_CASCADE_CHAN);

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		dma_wait_for_completion(PVR2_CASCADE_CHAN);

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	}

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	if (count++ < 10)

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		pr_debug("Got a pvr2 dma interrupt for channel %d\n",

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			 irq - HW_EVENT_PVR2_DMA);

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	xfer_complete = 1;

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	return IRQ_HANDLED;

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}

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static int pvr2_request_dma(struct dma_channel *chan)

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{

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	if (__raw_readl(PVR2_DMA_MODE) != 0)

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		return -EBUSY;

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	__raw_writel(0, PVR2_DMA_LMMODE0);

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	return 0;

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}

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static int pvr2_get_dma_residue(struct dma_channel *chan)

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{

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	return xfer_complete == 0;

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}

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static int pvr2_xfer_dma(struct dma_channel *chan)

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{

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	if (chan->sar || !chan->dar)

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		return -EINVAL;

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	xfer_complete = 0;

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	__raw_writel(chan->dar, PVR2_DMA_ADDR);

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	__raw_writel(chan->count, PVR2_DMA_COUNT);

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	__raw_writel(chan->mode & DMA_MODE_MASK, PVR2_DMA_MODE);

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	return 0;

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}

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static struct dma_ops pvr2_dma_ops = {

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	.request	= pvr2_request_dma,

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	.get_residue	= pvr2_get_dma_residue,

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	.xfer		= pvr2_xfer_dma,

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};

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static struct dma_info pvr2_dma_info = {

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	.name		= "pvr2_dmac",

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	.nr_channels	= 1,

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	.ops		= &pvr2_dma_ops,

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	.flags		= DMAC_CHANNELS_TEI_CAPABLE,

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};

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static int __init pvr2_dma_init(void)

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{

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	if (request_irq(HW_EVENT_PVR2_DMA, pvr2_dma_interrupt, 0,

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			"pvr2 DMA handler", NULL))

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		pr_err("Failed to register pvr2 DMA handler interrupt\n");

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	request_dma(PVR2_CASCADE_CHAN, "pvr2 cascade");

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	return register_dmac(&pvr2_dma_info);

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}

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static void __exit pvr2_dma_exit(void)

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{

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	free_dma(PVR2_CASCADE_CHAN);

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	free_irq(HW_EVENT_PVR2_DMA, 0);

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	unregister_dmac(&pvr2_dma_info);

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}

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subsys_initcall(pvr2_dma_init);

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module_exit(pvr2_dma_exit);

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MODULE_AUTHOR("Paul Mundt <[email protected]>");

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MODULE_DESCRIPTION("NEC PowerVR 2 DMA driver");

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MODULE_LICENSE("GPL v2");

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