aboutsummaryrefslogtreecommitdiffstats
path: root/arch/unicore32/kernel/dma.c
blob: ae441bc3122c60799a91c780fe1bdcc18b0c6e02 (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
/*
 * linux/arch/unicore32/kernel/dma.c
 *
 * Code specific to PKUnity SoC and UniCore ISA
 *
 *	Maintained by GUAN Xue-tao <gxt@mprc.pku.edu.cn>
 *	Copyright (C) 2001-2010 Guan Xuetao
 *
 * 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 <linux/io.h>

#include <asm/system.h>
#include <asm/irq.h>
#include <mach/hardware.h>
#include <mach/dma.h>

struct dma_channel {
	char *name;
	puv3_dma_prio prio;
	void (*irq_handler)(int, void *);
	void (*err_handler)(int, void *);
	void *data;
};

static struct dma_channel dma_channels[MAX_DMA_CHANNELS];

int puv3_request_dma(char *name, puv3_dma_prio prio,
			 void (*irq_handler)(int, void *),
			 void (*err_handler)(int, void *),
			 void *data)
{
	unsigned long flags;
	int i, found = 0;

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

	local_irq_save(flags);

	do {
		/* try grabbing a DMA channel with the requested priority */
		for (i = 0; i < MAX_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) {
		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;
}
EXPORT_SYMBOL(puv3_request_dma);

void puv3_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);
	dma_channels[dma_ch].name = NULL;
	dma_channels[dma_ch].err_handler = NULL;
	local_irq_restore(flags);
}
EXPORT_SYMBOL(puv3_free_dma);

static irqreturn_t dma_irq_handler(int irq, void *dev_id)
{
	int i, dint;

	dint = readl(DMAC_ITCSR);
	for (i = 0; i < MAX_DMA_CHANNELS; i++) {
		if (dint & DMAC_CHANNEL(i)) {
			struct dma_channel *channel = &dma_channels[i];

			/* Clear TC interrupt of channel i */
			writel(DMAC_CHANNEL(i), DMAC_ITCCR);
			writel(0, DMAC_ITCCR);

			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);
			}
		}
	}
	return IRQ_HANDLED;
}

static irqreturn_t dma_err_handler(int irq, void *dev_id)
{
	int i, dint;

	dint = readl(DMAC_IESR);
	for (i = 0; i < MAX_DMA_CHANNELS; i++) {
		if (dint & DMAC_CHANNEL(i)) {
			struct dma_channel *channel = &dma_channels[i];

			/* Clear Err interrupt of channel i */
			writel(DMAC_CHANNEL(i), DMAC_IECR);
			writel(0, DMAC_IECR);

			if (channel->name && channel->err_handler) {
				channel->err_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);
			}
		}
	}
	return IRQ_HANDLED;
}

int __init puv3_init_dma(void)
{
	int i, ret;

	/* dma channel priorities on v8 processors:
	 * ch 0 - 1  <--> (0) DMA_PRIO_HIGH
	 * ch 2 - 3  <--> (1) DMA_PRIO_MEDIUM
	 * ch 4 - 5  <--> (2) DMA_PRIO_LOW
	 */
	for (i = 0; i < MAX_DMA_CHANNELS; i++) {
		puv3_stop_dma(i);
		dma_channels[i].name = NULL;
		dma_channels[i].prio = min((i & 0x7) >> 1, DMA_PRIO_LOW);
	}

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

	ret = request_irq(IRQ_DMAERR, dma_err_handler, 0, "DMAERR", NULL);
	if (ret) {
		printk(KERN_CRIT "Can't register IRQ for DMAERR\n");
		free_irq(IRQ_DMA, "DMA");
		return ret;
	}

	return 0;
}

postcore_initcall(puv3_init_dma);