arch/arm/mach-pxa/dma.c

   1 /*
   2  *  linux/arch/arm/mach-pxa/dma.c
   3  *
   4  *  PXA DMA registration and IRQ dispatching
   5  *
   6  *  Author:     Nicolas Pitre
   7  *  Created:    Nov 15, 2001
   8  *  Copyright:  MontaVista Software Inc.
   9  *
  10  *  This program is free software; you can redistribute it and/or modify
  11  *  it under the terms of the GNU General Public License version 2 as
  12  *  published by the Free Software Foundation.
  13  */
  14
  15 #include <linux/module.h>
  16 #include <linux/init.h>
  17 #include <linux/kernel.h>
  18 #include <linux/interrupt.h>
  19 #include <linux/errno.h>
  20
  21 #include <asm/system.h>
  22 #include <asm/irq.h>
  23 #include <asm/hardware.h>
  24 #include <asm/dma.h>
  25
  26 #include <asm/arch/pxa-regs.h>
  27
  28 static struct dma_channel {
  29         char *name;
  30         void (*irq_handler)(int, void *);
  31         void *data;
  32 } dma_channels[PXA_DMA_CHANNELS];
  33
  34
  35 int pxa_request_dma (char *name, pxa_dma_prio prio,
  36                          void (*irq_handler)(int, void *),
  37                          void *data)
  38 {
  39         unsigned long flags;
  40         int i, found = 0;
  41
  42         /* basic sanity checks */
  43         if (!name || !irq_handler)
  44                 return -EINVAL;
  45
  46         local_irq_save(flags);
  47
  48         do {
  49                 /* try grabbing a DMA channel with the requested priority */
  50                 pxa_for_each_dma_prio (i, prio) {
  51                         if (!dma_channels[i].name) {
  52                                 found = 1;
  53                                 break;
  54                         }
  55                 }
  56                 /* if requested prio group is full, try a hier priority */
  57         } while (!found && prio--);
  58
  59         if (found) {
  60                 DCSR(i) = DCSR_STARTINTR|DCSR_ENDINTR|DCSR_BUSERR;
  61                 dma_channels[i].name = name;
  62                 dma_channels[i].irq_handler = irq_handler;
  63                 dma_channels[i].data = data;
  64         } else {
  65                 printk (KERN_WARNING "No more available DMA channels for %s\n", name);
  66                 i = -ENODEV;
  67         }
  68
  69         local_irq_restore(flags);
  70         return i;
  71 }
  72
  73 void pxa_free_dma (int dma_ch)
  74 {
  75         unsigned long flags;
  76
  77         if (!dma_channels[dma_ch].name) {
  78                 printk (KERN_CRIT
  79                         "%s: trying to free channel %d which is already freed\n",
  80                         __FUNCTION__, dma_ch);
  81                 return;
  82         }
  83
  84         local_irq_save(flags);
  85         DCSR(dma_ch) = DCSR_STARTINTR|DCSR_ENDINTR|DCSR_BUSERR;
  86         dma_channels[dma_ch].name = NULL;
  87         local_irq_restore(flags);
  88 }
  89
  90 static irqreturn_t dma_irq_handler(int irq, void *dev_id)
  91 {
  92         int i, dint = DINT;
  93
  94         for (i = 0; i < PXA_DMA_CHANNELS; i++) {
  95                 if (dint & (1 << i)) {
  96                         struct dma_channel *channel = &dma_channels[i];
  97                         if (channel->name && channel->irq_handler) {
  98                                 channel->irq_handler(i, channel->data);
  99                         } else {
 100                                 /*
 101                                  * IRQ for an unregistered DMA channel:
 102                                  * let's clear the interrupts and disable it.
 103                                  */
 104                                 printk (KERN_WARNING "spurious IRQ for DMA channel %d\n", i);
 105                                 DCSR(i) = DCSR_STARTINTR|DCSR_ENDINTR|DCSR_BUSERR;
 106                         }
 107                 }
 108         }
 109         return IRQ_HANDLED;
 110 }
 111
 112 static int __init pxa_dma_init (void)
 113 {
 114         int ret;
 115
 116         ret = request_irq (IRQ_DMA, dma_irq_handler, 0, "DMA", NULL);
 117         if (ret)
 118                 printk (KERN_CRIT "Wow!  Can't register IRQ for DMA\n");
 119         return ret;
 120 }
 121
 122 arch_initcall(pxa_dma_init);
 123
 124 EXPORT_SYMBOL(pxa_request_dma);
 125 EXPORT_SYMBOL(pxa_free_dma);
 126