1 // SPDX-License-Identifier: GPL-2.0-only
3 * linux/arch/arm/kernel/dma.c
5 * Copyright (C) 1995-2000 Russell King
7 * Front-end to the DMA handling. This handles the allocation/freeing
8 * of DMA channels, and provides a unified interface to the machines
11 #include <linux/module.h>
12 #include <linux/init.h>
13 #include <linux/spinlock.h>
14 #include <linux/errno.h>
15 #include <linux/scatterlist.h>
16 #include <linux/seq_file.h>
17 #include <linux/proc_fs.h>
21 #include <asm/mach/dma.h>
23 DEFINE_RAW_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)
41 sg_init_table(&dma->buf, 1);
52 * On certain platforms, we have to allocate an interrupt as well...
54 int request_dma(unsigned int chan, const char *device_id)
56 dma_t *dma = dma_channel(chan);
62 if (xchg(&dma->lock, 1) != 0)
65 dma->device_id = device_id;
70 if (dma->d_ops->request)
71 ret = dma->d_ops->request(chan, dma);
79 pr_err("dma: trying to allocate DMA%d\n", chan);
85 EXPORT_SYMBOL(request_dma);
90 * On certain platforms, we have to free interrupt as well...
92 void free_dma(unsigned int chan)
94 dma_t *dma = dma_channel(chan);
100 pr_err("dma%d: freeing active DMA\n", chan);
101 dma->d_ops->disable(chan, dma);
105 if (xchg(&dma->lock, 0) != 0) {
106 if (dma->d_ops->free)
107 dma->d_ops->free(chan, dma);
111 pr_err("dma%d: trying to free free DMA\n", chan);
115 pr_err("dma: trying to free DMA%d\n", chan);
117 EXPORT_SYMBOL(free_dma);
119 /* Set DMA Scatter-Gather list
121 void set_dma_sg (unsigned int chan, struct scatterlist *sg, int nr_sg)
123 dma_t *dma = dma_channel(chan);
126 pr_err("dma%d: altering DMA SG while DMA active\n", chan);
129 dma->sgcount = nr_sg;
132 EXPORT_SYMBOL(set_dma_sg);
136 * Copy address to the structure, and set the invalid bit
138 void __set_dma_addr (unsigned int chan, void *addr)
140 dma_t *dma = dma_channel(chan);
143 pr_err("dma%d: altering DMA address while DMA active\n", chan);
149 EXPORT_SYMBOL(__set_dma_addr);
151 /* Set DMA byte count
153 * Copy address to the structure, and set the invalid bit
155 void set_dma_count (unsigned int chan, unsigned long count)
157 dma_t *dma = dma_channel(chan);
160 pr_err("dma%d: altering DMA count while DMA active\n", chan);
166 EXPORT_SYMBOL(set_dma_count);
168 /* Set DMA direction mode
170 void set_dma_mode (unsigned int chan, unsigned int mode)
172 dma_t *dma = dma_channel(chan);
175 pr_err("dma%d: altering DMA mode while DMA active\n", chan);
177 dma->dma_mode = mode;
180 EXPORT_SYMBOL(set_dma_mode);
182 /* Enable DMA channel
184 void enable_dma (unsigned int chan)
186 dma_t *dma = dma_channel(chan);
191 if (dma->active == 0) {
193 dma->d_ops->enable(chan, dma);
198 pr_err("dma%d: trying to enable free DMA\n", chan);
201 EXPORT_SYMBOL(enable_dma);
203 /* Disable DMA channel
205 void disable_dma (unsigned int chan)
207 dma_t *dma = dma_channel(chan);
212 if (dma->active == 1) {
214 dma->d_ops->disable(chan, dma);
219 pr_err("dma%d: trying to disable free DMA\n", chan);
222 EXPORT_SYMBOL(disable_dma);
225 * Is the specified DMA channel active?
227 int dma_channel_active(unsigned int chan)
229 dma_t *dma = dma_channel(chan);
232 EXPORT_SYMBOL(dma_channel_active);
234 void set_dma_page(unsigned int chan, char pagenr)
236 pr_err("dma%d: trying to set_dma_page\n", chan);
238 EXPORT_SYMBOL(set_dma_page);
240 void set_dma_speed(unsigned int chan, int cycle_ns)
242 dma_t *dma = dma_channel(chan);
245 if (dma->d_ops->setspeed)
246 ret = dma->d_ops->setspeed(chan, dma, cycle_ns);
249 EXPORT_SYMBOL(set_dma_speed);
251 int get_dma_residue(unsigned int chan)
253 dma_t *dma = dma_channel(chan);
256 if (dma->d_ops->residue)
257 ret = dma->d_ops->residue(chan, dma);
261 EXPORT_SYMBOL(get_dma_residue);
263 #ifdef CONFIG_PROC_FS
264 static int proc_dma_show(struct seq_file *m, void *v)
268 for (i = 0 ; i < MAX_DMA_CHANNELS ; i++) {
269 dma_t *dma = dma_channel(i);
270 if (dma && dma->lock)
271 seq_printf(m, "%2d: %s\n", i, dma->device_id);
276 static int __init proc_dma_init(void)
278 proc_create_single("dma", 0, NULL, proc_dma_show);
282 __initcall(proc_dma_init);