1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * arch/sh/drivers/dma/dma-api.c
4 *
5 * SuperH-specific DMA management API
6 *
7 * Copyright (C) 2003, 2004, 2005 Paul Mundt
8 */
9 #include <linux/init.h>
10 #include <linux/module.h>
11 #include <linux/spinlock.h>
12 #include <linux/proc_fs.h>
13 #include <linux/seq_file.h>
14 #include <linux/list.h>
15 #include <linux/platform_device.h>
16 #include <linux/mm.h>
17 #include <linux/sched.h>
18 #include <linux/slab.h>
19 #include <asm/dma.h>
20
21 DEFINE_SPINLOCK(dma_spin_lock);
22 static LIST_HEAD(registered_dmac_list);
23
24 struct dma_info *get_dma_info(unsigned int chan)
25 {
26 struct dma_info *info;
27
28 /*
29 * Look for each DMAC's range to determine who the owner of
30 * the channel is.
31 */
32 list_for_each_entry(info, ®istered_dmac_list, list) {
33 if ((chan < info->first_vchannel_nr) ||
34 (chan >= info->first_vchannel_nr + info->nr_channels))
35 continue;
36
37 return info;
38 }
39
40 return NULL;
41 }
42 EXPORT_SYMBOL(get_dma_info);
43
44 static unsigned int get_nr_channels(void)
45 {
46 struct dma_info *info;
47 unsigned int nr = 0;
48
49 if (unlikely(list_empty(®istered_dmac_list)))
50 return nr;
51
52 list_for_each_entry(info, ®istered_dmac_list, list)
53 nr += info->nr_channels;
54
55 return nr;
56 }
57
58 struct dma_channel *get_dma_channel(unsigned int chan)
59 {
60 struct dma_info *info = get_dma_info(chan);
61 struct dma_channel *channel;
62 int i;
63
64 if (unlikely(!info))
65 return ERR_PTR(-EINVAL);
66
67 for (i = 0; i < info->nr_channels; i++) {
68 channel = &info->channels[i];
69 if (channel->vchan == chan)
70 return channel;
71 }
72
73 return NULL;
74 }
75 EXPORT_SYMBOL(get_dma_channel);
76
77 int get_dma_residue(unsigned int chan)
78 {
79 struct dma_info *info = get_dma_info(chan);
80 struct dma_channel *channel = get_dma_channel(chan);
81
82 if (info->ops->get_residue)
83 return info->ops->get_residue(channel);
84
85 return 0;
86 }
87 EXPORT_SYMBOL(get_dma_residue);
88
89 int request_dma(unsigned int chan, const char *dev_id)
90 {
91 struct dma_channel *channel = { 0 };
92 struct dma_info *info = get_dma_info(chan);
93 int result;
94
95 channel = get_dma_channel(chan);
96 if (atomic_xchg(&channel->busy, 1))
97 return -EBUSY;
98
99 strscpy(channel->dev_id, dev_id, sizeof(channel->dev_id));
100
101 if (info->ops->request) {
102 result = info->ops->request(channel);
103 if (result)
104 atomic_set(&channel->busy, 0);
105
106 return result;
107 }
108
109 return 0;
110 }
111 EXPORT_SYMBOL(request_dma);
112
113 void free_dma(unsigned int chan)
114 {
115 struct dma_info *info = get_dma_info(chan);
116 struct dma_channel *channel = get_dma_channel(chan);
117
118 if (info->ops->free)
119 info->ops->free(channel);
120
121 atomic_set(&channel->busy, 0);
122 }
123 EXPORT_SYMBOL(free_dma);
124
125 void dma_wait_for_completion(unsigned int chan)
126 {
127 struct dma_info *info = get_dma_info(chan);
128 struct dma_channel *channel = get_dma_channel(chan);
129
130 if (channel->flags & DMA_TEI_CAPABLE) {
131 wait_event(channel->wait_queue,
132 (info->ops->get_residue(channel) == 0));
133 return;
134 }
135
136 while (info->ops->get_residue(channel))
137 cpu_relax();
138 }
139 EXPORT_SYMBOL(dma_wait_for_completion);
140
141 void dma_configure_channel(unsigned int chan, unsigned long flags)
142 {
143 struct dma_info *info = get_dma_info(chan);
144 struct dma_channel *channel = get_dma_channel(chan);
145
146 if (info->ops->configure)
147 info->ops->configure(channel, flags);
148 }
149 EXPORT_SYMBOL(dma_configure_channel);
150
151 int dma_xfer(unsigned int chan, unsigned long from,
152 unsigned long to, size_t size, unsigned int mode)
153 {
154 struct dma_info *info = get_dma_info(chan);
155 struct dma_channel *channel = get_dma_channel(chan);
156
157 channel->sar = from;
158 channel->dar = to;
159 channel->count = size;
160 channel->mode = mode;
161
162 return info->ops->xfer(channel);
163 }
164 EXPORT_SYMBOL(dma_xfer);
165
166 static int dma_proc_show(struct seq_file *m, void *v)
167 {
168 struct dma_info *info = v;
169
170 if (list_empty(®istered_dmac_list))
171 return 0;
172
173 /*
174 * Iterate over each registered DMAC
175 */
176 list_for_each_entry(info, ®istered_dmac_list, list) {
177 int i;
178
179 /*
180 * Iterate over each channel
181 */
182 for (i = 0; i < info->nr_channels; i++) {
183 struct dma_channel *channel = info->channels + i;
184
185 if (!(channel->flags & DMA_CONFIGURED))
186 continue;
187
188 seq_printf(m, "%2d: %14s %s\n", i,
189 info->name, channel->dev_id);
190 }
191 }
192
193 return 0;
194 }
195
196 int register_dmac(struct dma_info *info)
197 {
198 unsigned int total_channels, i;
199
200 INIT_LIST_HEAD(&info->list);
201
202 printk(KERN_INFO "DMA: Registering %s handler (%d channel%s).\n",
203 info->name, info->nr_channels, info->nr_channels > 1 ? "s" : "");
204
205 BUG_ON((info->flags & DMAC_CHANNELS_CONFIGURED) && !info->channels);
206
207 info->pdev = platform_device_register_simple(info->name, -1,
208 NULL, 0);
209 if (IS_ERR(info->pdev))
210 return PTR_ERR(info->pdev);
211
212 /*
213 * Don't touch pre-configured channels
214 */
215 if (!(info->flags & DMAC_CHANNELS_CONFIGURED)) {
216 unsigned int size;
217
218 size = sizeof(struct dma_channel) * info->nr_channels;
219
220 info->channels = kzalloc(size, GFP_KERNEL);
221 if (!info->channels)
222 return -ENOMEM;
223 }
224
225 total_channels = get_nr_channels();
226 info->first_vchannel_nr = total_channels;
227 for (i = 0; i < info->nr_channels; i++) {
228 struct dma_channel *chan = &info->channels[i];
229
230 atomic_set(&chan->busy, 0);
231
232 chan->chan = info->first_channel_nr + i;
233 chan->vchan = info->first_channel_nr + i + total_channels;
234
235 memcpy(chan->dev_id, "Unused", 7);
236
237 if (info->flags & DMAC_CHANNELS_TEI_CAPABLE)
238 chan->flags |= DMA_TEI_CAPABLE;
239
240 init_waitqueue_head(&chan->wait_queue);
241 dma_create_sysfs_files(chan, info);
242 }
243
244 list_add(&info->list, ®istered_dmac_list);
245
246 return 0;
247 }
248 EXPORT_SYMBOL(register_dmac);
249
250 void unregister_dmac(struct dma_info *info)
251 {
252 unsigned int i;
253
254 for (i = 0; i < info->nr_channels; i++)
255 dma_remove_sysfs_files(info->channels + i, info);
256
257 if (!(info->flags & DMAC_CHANNELS_CONFIGURED))
258 kfree(info->channels);
259
260 list_del(&info->list);
261 platform_device_unregister(info->pdev);
262 }
263 EXPORT_SYMBOL(unregister_dmac);
264
265 static int __init dma_api_init(void)
266 {
267 printk(KERN_NOTICE "DMA: Registering DMA API.\n");
268 return proc_create_single("dma", 0, NULL, dma_proc_show) ? 0 : -ENOMEM;
269 }
270 subsys_initcall(dma_api_init);
271
272 MODULE_AUTHOR("Paul Mundt <lethal@linux-sh.org>");
273 MODULE_DESCRIPTION("DMA API for SuperH");
274 MODULE_LICENSE("GPL v2");
275
Linux® is a registered trademark of Linus Torvalds in the United States and other countries.
TOMOYO® is a registered trademark of NTT DATA CORPORATION.