99532559dc
Patch from Nicolas Pitre Intel PXA27x developers manual section 5.4.1.1 lists a priority distribution for the DMA channels differently than what the code currently assumes. This patch fixes that. Noticed by Simon Vogl <vogl@soft.uni-linz.ac.at> Signed-off-by: Nicolas Pitre <nico@cam.org> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
126 lines
2.8 KiB
C
126 lines
2.8 KiB
C
/*
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* linux/arch/arm/mach-pxa/dma.c
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*
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* PXA DMA registration and IRQ dispatching
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*
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* Author: Nicolas Pitre
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* Created: Nov 15, 2001
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* Copyright: MontaVista Software Inc.
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*/
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#include <linux/module.h>
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#include <linux/init.h>
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#include <linux/kernel.h>
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#include <linux/interrupt.h>
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#include <linux/errno.h>
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#include <asm/system.h>
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#include <asm/irq.h>
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#include <asm/hardware.h>
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#include <asm/dma.h>
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#include <asm/arch/pxa-regs.h>
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static struct dma_channel {
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char *name;
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void (*irq_handler)(int, void *, struct pt_regs *);
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void *data;
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} dma_channels[PXA_DMA_CHANNELS];
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int pxa_request_dma (char *name, pxa_dma_prio prio,
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void (*irq_handler)(int, void *, struct pt_regs *),
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void *data)
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{
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unsigned long flags;
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int i, found = 0;
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/* basic sanity checks */
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if (!name || !irq_handler)
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return -EINVAL;
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local_irq_save(flags);
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do {
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/* try grabbing a DMA channel with the requested priority */
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pxa_for_each_dma_prio (i, prio) {
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if (!dma_channels[i].name) {
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found = 1;
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break;
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}
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}
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/* if requested prio group is full, try a hier priority */
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} while (!found && prio--);
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if (found) {
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DCSR(i) = DCSR_STARTINTR|DCSR_ENDINTR|DCSR_BUSERR;
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dma_channels[i].name = name;
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dma_channels[i].irq_handler = irq_handler;
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dma_channels[i].data = data;
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} else {
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printk (KERN_WARNING "No more available DMA channels for %s\n", name);
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i = -ENODEV;
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}
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local_irq_restore(flags);
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return i;
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}
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void pxa_free_dma (int dma_ch)
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{
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unsigned long flags;
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if (!dma_channels[dma_ch].name) {
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printk (KERN_CRIT
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"%s: trying to free channel %d which is already freed\n",
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__FUNCTION__, dma_ch);
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return;
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}
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local_irq_save(flags);
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DCSR(dma_ch) = DCSR_STARTINTR|DCSR_ENDINTR|DCSR_BUSERR;
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dma_channels[dma_ch].name = NULL;
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local_irq_restore(flags);
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}
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static irqreturn_t dma_irq_handler(int irq, void *dev_id, struct pt_regs *regs)
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{
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int i, dint = DINT;
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for (i = 0; i < PXA_DMA_CHANNELS; i++) {
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if (dint & (1 << i)) {
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struct dma_channel *channel = &dma_channels[i];
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if (channel->name && channel->irq_handler) {
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channel->irq_handler(i, channel->data, regs);
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} else {
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/*
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* IRQ for an unregistered DMA channel:
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* let's clear the interrupts and disable it.
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*/
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printk (KERN_WARNING "spurious IRQ for DMA channel %d\n", i);
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DCSR(i) = DCSR_STARTINTR|DCSR_ENDINTR|DCSR_BUSERR;
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}
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}
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}
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return IRQ_HANDLED;
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}
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static int __init pxa_dma_init (void)
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{
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int ret;
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ret = request_irq (IRQ_DMA, dma_irq_handler, 0, "DMA", NULL);
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if (ret)
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printk (KERN_CRIT "Wow! Can't register IRQ for DMA\n");
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return ret;
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}
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arch_initcall(pxa_dma_init);
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EXPORT_SYMBOL(pxa_request_dma);
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EXPORT_SYMBOL(pxa_free_dma);
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