1 /*
2 * linux/arch/unicore32/kernel/dma.c
3 *
4 * Code specific to PKUnity SoC and UniCore ISA
5 *
6 * Maintained by GUAN Xue-tao <gxt@mprc.pku.edu.cn>
7 * Copyright (C) 2001-2010 Guan Xuetao
8 *
9 * This program is free software; you can redistribute it and/or modify
10 * it under the terms of the GNU General Public License version 2 as
11 * published by the Free Software Foundation.
12 */
13
14 #include <linux/module.h>
15 #include <linux/init.h>
16 #include <linux/kernel.h>
17 #include <linux/interrupt.h>
18 #include <linux/errno.h>
19 #include <linux/io.h>
20
21 #include <asm/irq.h>
22 #include <mach/hardware.h>
23 #include <mach/dma.h>
24
25 struct dma_channel {
26 char *name;
27 puv3_dma_prio prio;
28 void (*irq_handler)(int, void *);
29 void (*err_handler)(int, void *);
30 void *data;
31 };
32
33 static struct dma_channel dma_channels[MAX_DMA_CHANNELS];
34
puv3_request_dma(char * name,puv3_dma_prio prio,void (* irq_handler)(int,void *),void (* err_handler)(int,void *),void * data)35 int puv3_request_dma(char *name, puv3_dma_prio prio,
36 void (*irq_handler)(int, void *),
37 void (*err_handler)(int, void *),
38 void *data)
39 {
40 unsigned long flags;
41 int i, found = 0;
42
43 /* basic sanity checks */
44 if (!name)
45 return -EINVAL;
46
47 local_irq_save(flags);
48
49 do {
50 /* try grabbing a DMA channel with the requested priority */
51 for (i = 0; i < MAX_DMA_CHANNELS; i++) {
52 if ((dma_channels[i].prio == prio) &&
53 !dma_channels[i].name) {
54 found = 1;
55 break;
56 }
57 }
58 /* if requested prio group is full, try a hier priority */
59 } while (!found && prio--);
60
61 if (found) {
62 dma_channels[i].name = name;
63 dma_channels[i].irq_handler = irq_handler;
64 dma_channels[i].err_handler = err_handler;
65 dma_channels[i].data = data;
66 } else {
67 printk(KERN_WARNING "No more available DMA channels for %s\n",
68 name);
69 i = -ENODEV;
70 }
71
72 local_irq_restore(flags);
73 return i;
74 }
75 EXPORT_SYMBOL(puv3_request_dma);
76
puv3_free_dma(int dma_ch)77 void puv3_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 dma_channels[dma_ch].name = NULL;
90 dma_channels[dma_ch].err_handler = NULL;
91 local_irq_restore(flags);
92 }
93 EXPORT_SYMBOL(puv3_free_dma);
94
dma_irq_handler(int irq,void * dev_id)95 static irqreturn_t dma_irq_handler(int irq, void *dev_id)
96 {
97 int i, dint;
98
99 dint = readl(DMAC_ITCSR);
100 for (i = 0; i < MAX_DMA_CHANNELS; i++) {
101 if (dint & DMAC_CHANNEL(i)) {
102 struct dma_channel *channel = &dma_channels[i];
103
104 /* Clear TC interrupt of channel i */
105 writel(DMAC_CHANNEL(i), DMAC_ITCCR);
106 writel(0, DMAC_ITCCR);
107
108 if (channel->name && channel->irq_handler) {
109 channel->irq_handler(i, channel->data);
110 } else {
111 /*
112 * IRQ for an unregistered DMA channel:
113 * let's clear the interrupts and disable it.
114 */
115 printk(KERN_WARNING "spurious IRQ for"
116 " DMA channel %d\n", i);
117 }
118 }
119 }
120 return IRQ_HANDLED;
121 }
122
dma_err_handler(int irq,void * dev_id)123 static irqreturn_t dma_err_handler(int irq, void *dev_id)
124 {
125 int i, dint;
126
127 dint = readl(DMAC_IESR);
128 for (i = 0; i < MAX_DMA_CHANNELS; i++) {
129 if (dint & DMAC_CHANNEL(i)) {
130 struct dma_channel *channel = &dma_channels[i];
131
132 /* Clear Err interrupt of channel i */
133 writel(DMAC_CHANNEL(i), DMAC_IECR);
134 writel(0, DMAC_IECR);
135
136 if (channel->name && channel->err_handler) {
137 channel->err_handler(i, channel->data);
138 } else {
139 /*
140 * IRQ for an unregistered DMA channel:
141 * let's clear the interrupts and disable it.
142 */
143 printk(KERN_WARNING "spurious IRQ for"
144 " DMA channel %d\n", i);
145 }
146 }
147 }
148 return IRQ_HANDLED;
149 }
150
puv3_init_dma(void)151 int __init puv3_init_dma(void)
152 {
153 int i, ret;
154
155 /* dma channel priorities on v8 processors:
156 * ch 0 - 1 <--> (0) DMA_PRIO_HIGH
157 * ch 2 - 3 <--> (1) DMA_PRIO_MEDIUM
158 * ch 4 - 5 <--> (2) DMA_PRIO_LOW
159 */
160 for (i = 0; i < MAX_DMA_CHANNELS; i++) {
161 puv3_stop_dma(i);
162 dma_channels[i].name = NULL;
163 dma_channels[i].prio = min((i & 0x7) >> 1, DMA_PRIO_LOW);
164 }
165
166 ret = request_irq(IRQ_DMA, dma_irq_handler, 0, "DMA", NULL);
167 if (ret) {
168 printk(KERN_CRIT "Can't register IRQ for DMA\n");
169 return ret;
170 }
171
172 ret = request_irq(IRQ_DMAERR, dma_err_handler, 0, "DMAERR", NULL);
173 if (ret) {
174 printk(KERN_CRIT "Can't register IRQ for DMAERR\n");
175 free_irq(IRQ_DMA, "DMA");
176 return ret;
177 }
178
179 return 0;
180 }
181
182 postcore_initcall(puv3_init_dma);
183
