summaryrefslogtreecommitdiffstats
path: root/arch/arm/mach-imx/dma.c
blob: 71a59e196166cc00c4d9d31821f1f1aa3a16f44c (plain)
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
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
/*
 *  linux/arch/arm/mach-imx/dma.c
 *
 *  imx DMA registration and IRQ dispatching
 *
 *  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.
 *
 *  03/03/2004 Sascha Hauer <sascha@saschahauer.de>
 *             initial version heavily inspired by
 *             linux/arch/arm/mach-pxa/dma.c
 */

#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 <asm/hardware.h>
#include <asm/dma.h>

static struct dma_channel {
	char *name;
	void (*irq_handler) (int, void *, struct pt_regs *);
	void (*err_handler) (int, void *, struct pt_regs *);
	void *data;
} dma_channels[11];

/* set err_handler to NULL to have the standard info-only error handler */
int
imx_request_dma(char *name, imx_dma_prio prio,
		void (*irq_handler) (int, void *, struct pt_regs *),
		void (*err_handler) (int, void *, struct pt_regs *), void *data)
{
	unsigned long flags;
	int i, found = 0;

	/* basic sanity checks */
	if (!name || !irq_handler)
		return -EINVAL;

	local_irq_save(flags);

	/* try grabbing a DMA channel with the requested priority */
	for (i = prio; i < prio + (prio == DMA_PRIO_LOW) ? 8 : 4; i++) {
		if (!dma_channels[i].name) {
			found = 1;
			break;
		}
	}

	if (!found) {
		/* requested prio group is full, try hier priorities */
		for (i = prio - 1; i >= 0; i--) {
			if (!dma_channels[i].name) {
				found = 1;
				break;
			}
		}
	}

	if (found) {
		DIMR &= ~(1 << i);
		dma_channels[i].name = name;
		dma_channels[i].irq_handler = irq_handler;
		dma_channels[i].err_handler = err_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;
}

void
imx_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",
		       __FUNCTION__, dma_ch);
		return;
	}

	local_irq_save(flags);
	DIMR &= ~(1 << dma_ch);
	dma_channels[dma_ch].name = NULL;
	local_irq_restore(flags);
}

static irqreturn_t
dma_err_handler(int irq, void *dev_id, struct pt_regs *regs)
{
	int i, disr = DISR;
	struct dma_channel *channel;
	unsigned int err_mask = DBTOSR | DRTOSR | DSESR | DBOSR;

	DISR = disr;
	for (i = 0; i < 11; i++) {
		channel = &dma_channels[i];

		if ( (err_mask & 1<<i) && channel->name && channel->err_handler) {
			channel->err_handler(i, channel->data, regs);
			continue;
		}

		if (DBTOSR & (1 << i)) {
			printk(KERN_WARNING
			       "Burst timeout on channel %d (%s)\n",
			       i, channel->name);
			DBTOSR |= (1 << i);
		}
		if (DRTOSR & (1 << i)) {
			printk(KERN_WARNING
			       "Request timeout on channel %d (%s)\n",
			       i, channel->name);
			DRTOSR |= (1 << i);
		}
		if (DSESR & (1 << i)) {
			printk(KERN_WARNING
			       "Transfer timeout on channel %d (%s)\n",
			       i, channel->name);
			DSESR |= (1 << i);
		}
		if (DBOSR & (1 << i)) {
			printk(KERN_WARNING
			       "Buffer overflow timeout on channel %d (%s)\n",
			       i, channel->name);
			DBOSR |= (1 << i);
		}
	}
	return IRQ_HANDLED;
}

static irqreturn_t
dma_irq_handler(int irq, void *dev_id, struct pt_regs *regs)
{
	int i, disr = DISR;

	DISR = disr;
	for (i = 0; i < 11; i++) {
		if (disr & (1 << i)) {
			struct dma_channel *channel = &dma_channels[i];
			if (channel->name && channel->irq_handler) {
				channel->irq_handler(i, channel->data, regs);
			} 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);
			}
		}
	}
	return IRQ_HANDLED;
}

static int __init
imx_dma_init(void)
{
	int ret;

	/* reset DMA module */
	DCR = DCR_DRST;

	ret = request_irq(DMA_INT, dma_irq_handler, 0, "DMA", NULL);
	if (ret) {
		printk(KERN_CRIT "Wow!  Can't register IRQ for DMA\n");
		return ret;
	}

	ret = request_irq(DMA_ERR, dma_err_handler, 0, "DMA", NULL);
	if (ret) {
		printk(KERN_CRIT "Wow!  Can't register ERRIRQ for DMA\n");
		free_irq(DMA_INT, NULL);
	}

	/* enable DMA module */
	DCR = DCR_DEN;

	/* clear all interrupts */
	DISR = 0x3ff;

	/* enable interrupts */
	DIMR = 0;

	return ret;
}

arch_initcall(imx_dma_init);

EXPORT_SYMBOL(imx_request_dma);
EXPORT_SYMBOL(imx_free_dma);
OpenPOWER on IntegriCloud