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/*
* linux/arch/arm/plat-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 <mach/hardware.h>
#include <mach/dma.h>
struct dma_channel {
char *name;
pxa_dma_prio prio;
void (*irq_handler)(int, void *);
void *data;
};
static struct dma_channel *dma_channels;
static int num_dma_channels;
int pxa_request_dma (char *name, pxa_dma_prio prio,
void (*irq_handler)(int, void *),
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 */
for (i = 0; i < num_dma_channels; i++) {
if ((dma_channels[i].prio == prio) &&
!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;
}
EXPORT_SYMBOL(pxa_request_dma);
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",
__func__, 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);
}
EXPORT_SYMBOL(pxa_free_dma);
static irqreturn_t dma_irq_handler(int irq, void *dev_id)
{
int i, dint = DINT;
struct dma_channel *channel;
while (dint) {
i = __ffs(dint);
dint &= (dint - 1);
channel = &dma_channels[i];
if (channel->name && channel->irq_handler) {
channel->irq_handler(i, channel->data);
} 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;
}
int __init pxa_init_dma(int irq, int num_ch)
{
int i, ret;
dma_channels = kzalloc(sizeof(struct dma_channel) * num_ch, GFP_KERNEL);
if (dma_channels == NULL)
return -ENOMEM;
/* dma channel priorities on pxa2xx processors:
* ch 0 - 3, 16 - 19 <--> (0) DMA_PRIO_HIGH
* ch 4 - 7, 20 - 23 <--> (1) DMA_PRIO_MEDIUM
* ch 8 - 15, 24 - 31 <--> (2) DMA_PRIO_LOW
*/
for (i = 0; i < num_ch; i++) {
DCSR(i) = 0;
dma_channels[i].prio = min((i & 0xf) >> 2, DMA_PRIO_LOW);
}
ret = request_irq(irq, dma_irq_handler, IRQF_DISABLED, "DMA", NULL);
if (ret) {
printk (KERN_CRIT "Wow! Can't register IRQ for DMA\n");
kfree(dma_channels);
return ret;
}
num_dma_channels = num_ch;
return 0;
}
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