2 * linux/arch/arm/kernel/dma.c
4 * Copyright (C) 1995-2000 Russell King
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License version 2 as
8 * published by the Free Software Foundation.
10 * Front-end to the DMA handling. This handles the allocation/freeing
11 * of DMA channels, and provides a unified interface to the machines
14 #include <linux/module.h>
15 #include <linux/init.h>
16 #include <linux/spinlock.h>
17 #include <linux/errno.h>
21 #include <asm/mach/dma.h>
23 DEFINE_SPINLOCK(dma_spin_lock);
24 EXPORT_SYMBOL(dma_spin_lock);
26 static dma_t *dma_chan[MAX_DMA_CHANNELS];
28 static inline dma_t *dma_channel(unsigned int chan)
30 if (chan >= MAX_DMA_CHANNELS)
33 return dma_chan[chan];
36 int __init isa_dma_add(unsigned int chan, dma_t *dma)
49 * On certain platforms, we have to allocate an interrupt as well...
51 int request_dma(unsigned int chan, const char *device_id)
53 dma_t *dma = dma_channel(chan);
59 if (xchg(&dma->lock, 1) != 0)
62 dma->device_id = device_id;
67 if (dma->d_ops->request)
68 ret = dma->d_ops->request(chan, dma);
76 printk(KERN_ERR "dma: trying to allocate DMA%d\n", chan);
82 EXPORT_SYMBOL(request_dma);
87 * On certain platforms, we have to free interrupt as well...
89 void free_dma(unsigned int chan)
91 dma_t *dma = dma_channel(chan);
97 printk(KERN_ERR "dma%d: freeing active DMA\n", chan);
98 dma->d_ops->disable(chan, dma);
102 if (xchg(&dma->lock, 0) != 0) {
103 if (dma->d_ops->free)
104 dma->d_ops->free(chan, dma);
108 printk(KERN_ERR "dma%d: trying to free free DMA\n", chan);
112 printk(KERN_ERR "dma: trying to free DMA%d\n", chan);
114 EXPORT_SYMBOL(free_dma);
116 /* Set DMA Scatter-Gather list
118 void set_dma_sg (unsigned int chan, struct scatterlist *sg, int nr_sg)
120 dma_t *dma = dma_channel(chan);
123 printk(KERN_ERR "dma%d: altering DMA SG while "
124 "DMA active\n", chan);
127 dma->sgcount = nr_sg;
130 EXPORT_SYMBOL(set_dma_sg);
134 * Copy address to the structure, and set the invalid bit
136 void __set_dma_addr (unsigned int chan, void *addr)
138 dma_t *dma = dma_channel(chan);
141 printk(KERN_ERR "dma%d: altering DMA address while "
142 "DMA active\n", chan);
148 EXPORT_SYMBOL(__set_dma_addr);
150 /* Set DMA byte count
152 * Copy address to the structure, and set the invalid bit
154 void set_dma_count (unsigned int chan, unsigned long count)
156 dma_t *dma = dma_channel(chan);
159 printk(KERN_ERR "dma%d: altering DMA count while "
160 "DMA active\n", chan);
166 EXPORT_SYMBOL(set_dma_count);
168 /* Set DMA direction mode
170 void set_dma_mode (unsigned int chan, dmamode_t mode)
172 dma_t *dma = dma_channel(chan);
175 printk(KERN_ERR "dma%d: altering DMA mode while "
176 "DMA active\n", chan);
178 dma->dma_mode = mode;
181 EXPORT_SYMBOL(set_dma_mode);
183 /* Enable DMA channel
185 void enable_dma (unsigned int chan)
187 dma_t *dma = dma_channel(chan);
192 if (dma->active == 0) {
194 dma->d_ops->enable(chan, dma);
199 printk(KERN_ERR "dma%d: trying to enable free DMA\n", chan);
202 EXPORT_SYMBOL(enable_dma);
204 /* Disable DMA channel
206 void disable_dma (unsigned int chan)
208 dma_t *dma = dma_channel(chan);
213 if (dma->active == 1) {
215 dma->d_ops->disable(chan, dma);
220 printk(KERN_ERR "dma%d: trying to disable free DMA\n", chan);
223 EXPORT_SYMBOL(disable_dma);
226 * Is the specified DMA channel active?
228 int dma_channel_active(unsigned int chan)
230 dma_t *dma = dma_channel(chan);
233 EXPORT_SYMBOL(dma_channel_active);
235 void set_dma_page(unsigned int chan, char pagenr)
237 printk(KERN_ERR "dma%d: trying to set_dma_page\n", chan);
239 EXPORT_SYMBOL(set_dma_page);
241 void set_dma_speed(unsigned int chan, int cycle_ns)
243 dma_t *dma = dma_channel(chan);
246 if (dma->d_ops->setspeed)
247 ret = dma->d_ops->setspeed(chan, dma, cycle_ns);
250 EXPORT_SYMBOL(set_dma_speed);
252 int get_dma_residue(unsigned int chan)
254 dma_t *dma = dma_channel(chan);
257 if (dma->d_ops->residue)
258 ret = dma->d_ops->residue(chan, dma);
262 EXPORT_SYMBOL(get_dma_residue);