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 <mach/hardware.h>
24 #include <mach/dma.h>
25
26 #include <mach/pxa-regs.h>
27
28 struct dma_channel {
29 char *name;
30 pxa_dma_prio prio;
31 void (*irq_handler)(int, void *);
32 void *data;
33 };
34
35 static struct dma_channel *dma_channels;
36 static int num_dma_channels;
37
pxa_request_dma(char * name,pxa_dma_prio prio,void (* irq_handler)(int,void *),void * data)38 int pxa_request_dma (char *name, pxa_dma_prio prio,
39 void (*irq_handler)(int, void *),
40 void *data)
41 {
42 unsigned long flags;
43 int i, found = 0;
44
45 /* basic sanity checks */
46 if (!name || !irq_handler)
47 return -EINVAL;
48
49 local_irq_save(flags);
50
51 do {
52 /* try grabbing a DMA channel with the requested priority */
53 for (i = 0; i < num_dma_channels; i++) {
54 if ((dma_channels[i].prio == prio) &&
55 !dma_channels[i].name) {
56 found = 1;
57 break;
58 }
59 }
60 /* if requested prio group is full, try a hier priority */
61 } while (!found && prio--);
62
63 if (found) {
64 DCSR(i) = DCSR_STARTINTR|DCSR_ENDINTR|DCSR_BUSERR;
65 dma_channels[i].name = name;
66 dma_channels[i].irq_handler = irq_handler;
67 dma_channels[i].data = data;
68 } else {
69 printk (KERN_WARNING "No more available DMA channels for %s\n", name);
70 i = -ENODEV;
71 }
72
73 local_irq_restore(flags);
74 return i;
75 }
76
pxa_free_dma(int dma_ch)77 void pxa_free_dma (int dma_ch)
78 {
79 unsigned long flags;
80
81 if (!dma_channels[dma_ch].name) {
82 printk (KERN_CRIT
83 "%s: trying to free channel %d which is already freed\n",
84 __func__, dma_ch);
85 return;
86 }
87
88 local_irq_save(flags);
89 DCSR(dma_ch) = DCSR_STARTINTR|DCSR_ENDINTR|DCSR_BUSERR;
90 dma_channels[dma_ch].name = NULL;
91 local_irq_restore(flags);
92 }
93
dma_irq_handler(int irq,void * dev_id)94 static irqreturn_t dma_irq_handler(int irq, void *dev_id)
95 {
96 int i, dint = DINT;
97
98 for (i = 0; i < num_dma_channels; i++) {
99 if (dint & (1 << i)) {
100 struct dma_channel *channel = &dma_channels[i];
101 if (channel->name && channel->irq_handler) {
102 channel->irq_handler(i, channel->data);
103 } else {
104 /*
105 * IRQ for an unregistered DMA channel:
106 * let's clear the interrupts and disable it.
107 */
108 printk (KERN_WARNING "spurious IRQ for DMA channel %d\n", i);
109 DCSR(i) = DCSR_STARTINTR|DCSR_ENDINTR|DCSR_BUSERR;
110 }
111 }
112 }
113 return IRQ_HANDLED;
114 }
115
pxa_init_dma(int num_ch)116 int __init pxa_init_dma(int num_ch)
117 {
118 int i, ret;
119
120 dma_channels = kzalloc(sizeof(struct dma_channel) * num_ch, GFP_KERNEL);
121 if (dma_channels == NULL)
122 return -ENOMEM;
123
124 /* dma channel priorities on pxa2xx processors:
125 * ch 0 - 3, 16 - 19 <--> (0) DMA_PRIO_HIGH
126 * ch 4 - 7, 20 - 23 <--> (1) DMA_PRIO_MEDIUM
127 * ch 8 - 15, 24 - 31 <--> (2) DMA_PRIO_LOW
128 */
129 for (i = 0; i < num_ch; i++) {
130 DCSR(i) = 0;
131 dma_channels[i].prio = min((i & 0xf) >> 2, DMA_PRIO_LOW);
132 }
133
134 ret = request_irq(IRQ_DMA, dma_irq_handler, IRQF_DISABLED, "DMA", NULL);
135 if (ret) {
136 printk (KERN_CRIT "Wow! Can't register IRQ for DMA\n");
137 kfree(dma_channels);
138 return ret;
139 }
140
141 num_dma_channels = num_ch;
142 return 0;
143 }
144
145 EXPORT_SYMBOL(pxa_request_dma);
146 EXPORT_SYMBOL(pxa_free_dma);
147