Merge branch 'for_paulus' of master.kernel.org:/pub/scm/linux/kernel/git/galak/powerpc
[linux-2.6] / 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