1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
|
/*
* 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;
for (i = 0; i < num_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);
} 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;
}
|
