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