tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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linux
1// SPDX-License-Identifier: GPL-2.0+
2/*
3 * COMEDI ISA DMA support functions
4 * Copyright (c) 2014 H Hartley Sweeten <hsweeten@visionengravers.com>
5 */
6
7#include <linux/module.h>
8#include <linux/slab.h>
9#include <linux/delay.h>
10#include <linux/dma-mapping.h>
11#include <linux/isa-dma.h>
12#include <linux/comedi/comedidev.h>
13#include <linux/comedi/comedi_isadma.h>
14
15/**
16 * comedi_isadma_program - program and enable an ISA DMA transfer
17 * @desc: the ISA DMA cookie to program and enable
18 */
19void comedi_isadma_program(struct comedi_isadma_desc *desc)
20{
21 unsigned long flags;
22
23 flags = claim_dma_lock();
24 clear_dma_ff(desc->chan);
25 set_dma_mode(desc->chan, desc->mode);
26 set_dma_addr(desc->chan, desc->hw_addr);
27 set_dma_count(desc->chan, desc->size);
28 enable_dma(desc->chan);
29 release_dma_lock(flags);
30}
31EXPORT_SYMBOL_GPL(comedi_isadma_program);
32
33/**
34 * comedi_isadma_disable - disable the ISA DMA channel
35 * @dma_chan: the DMA channel to disable
36 *
37 * Returns the residue (remaining bytes) left in the DMA transfer.
38 */
39unsigned int comedi_isadma_disable(unsigned int dma_chan)
40{
41 unsigned long flags;
42 unsigned int residue;
43
44 flags = claim_dma_lock();
45 disable_dma(dma_chan);
46 residue = get_dma_residue(dma_chan);
47 release_dma_lock(flags);
48
49 return residue;
50}
51EXPORT_SYMBOL_GPL(comedi_isadma_disable);
52
53/**
54 * comedi_isadma_disable_on_sample - disable the ISA DMA channel
55 * @dma_chan: the DMA channel to disable
56 * @size: the sample size (in bytes)
57 *
58 * Returns the residue (remaining bytes) left in the DMA transfer.
59 */
60unsigned int comedi_isadma_disable_on_sample(unsigned int dma_chan,
61 unsigned int size)
62{
63 int stalled = 0;
64 unsigned long flags;
65 unsigned int residue;
66 unsigned int new_residue;
67
68 residue = comedi_isadma_disable(dma_chan);
69 while (residue % size) {
70 /* residue is a partial sample, enable DMA to allow more data */
71 flags = claim_dma_lock();
72 enable_dma(dma_chan);
73 release_dma_lock(flags);
74
75 udelay(2);
76 new_residue = comedi_isadma_disable(dma_chan);
77
78 /* is DMA stalled? */
79 if (new_residue == residue) {
80 stalled++;
81 if (stalled > 10)
82 break;
83 } else {
84 residue = new_residue;
85 stalled = 0;
86 }
87 }
88 return residue;
89}
90EXPORT_SYMBOL_GPL(comedi_isadma_disable_on_sample);
91
92/**
93 * comedi_isadma_poll - poll the current DMA transfer
94 * @dma: the ISA DMA to poll
95 *
96 * Returns the position (in bytes) of the current DMA transfer.
97 */
98unsigned int comedi_isadma_poll(struct comedi_isadma *dma)
99{
100 struct comedi_isadma_desc *desc = &dma->desc[dma->cur_dma];
101 unsigned long flags;
102 unsigned int result;
103 unsigned int result1;
104
105 flags = claim_dma_lock();
106 clear_dma_ff(desc->chan);
107 if (!isa_dma_bridge_buggy)
108 disable_dma(desc->chan);
109 result = get_dma_residue(desc->chan);
110 /*
111 * Read the counter again and choose higher value in order to
112 * avoid reading during counter lower byte roll over if the
113 * isa_dma_bridge_buggy is set.
114 */
115 result1 = get_dma_residue(desc->chan);
116 if (!isa_dma_bridge_buggy)
117 enable_dma(desc->chan);
118 release_dma_lock(flags);
119
120 if (result < result1)
121 result = result1;
122 if (result >= desc->size || result == 0)
123 return 0;
124 return desc->size - result;
125}
126EXPORT_SYMBOL_GPL(comedi_isadma_poll);
127
128/**
129 * comedi_isadma_set_mode - set the ISA DMA transfer direction
130 * @desc: the ISA DMA cookie to set
131 * @dma_dir: the DMA direction
132 */
133void comedi_isadma_set_mode(struct comedi_isadma_desc *desc, char dma_dir)
134{
135 desc->mode = (dma_dir == COMEDI_ISADMA_READ) ? DMA_MODE_READ
136 : DMA_MODE_WRITE;
137}
138EXPORT_SYMBOL_GPL(comedi_isadma_set_mode);
139
140/**
141 * comedi_isadma_alloc - allocate and initialize the ISA DMA
142 * @dev: comedi_device struct
143 * @n_desc: the number of cookies to allocate
144 * @dma_chan1: DMA channel for the first cookie
145 * @dma_chan2: DMA channel for the second cookie
146 * @maxsize: the size of the buffer to allocate for each cookie
147 * @dma_dir: the DMA direction
148 *
149 * Returns the allocated and initialized ISA DMA or NULL if anything fails.
150 */
151struct comedi_isadma *comedi_isadma_alloc(struct comedi_device *dev,
152 int n_desc, unsigned int dma_chan1,
153 unsigned int dma_chan2,
154 unsigned int maxsize, char dma_dir)
155{
156 struct comedi_isadma *dma = NULL;
157 struct comedi_isadma_desc *desc;
158 unsigned int dma_chans[2];
159 int i;
160
161 if (n_desc < 1 || n_desc > 2)
162 goto no_dma;
163
164 dma = kzalloc(sizeof(*dma), GFP_KERNEL);
165 if (!dma)
166 goto no_dma;
167
168 desc = kcalloc(n_desc, sizeof(*desc), GFP_KERNEL);
169 if (!desc)
170 goto no_dma;
171 dma->desc = desc;
172 dma->n_desc = n_desc;
173 if (dev->hw_dev) {
174 dma->dev = dev->hw_dev;
175 } else {
176 /* Fall back to using the "class" device. */
177 if (!dev->class_dev)
178 goto no_dma;
179 /* Need 24-bit mask for ISA DMA. */
180 if (dma_coerce_mask_and_coherent(dev->class_dev,
181 DMA_BIT_MASK(24))) {
182 goto no_dma;
183 }
184 dma->dev = dev->class_dev;
185 }
186
187 dma_chans[0] = dma_chan1;
188 if (dma_chan2 == 0 || dma_chan2 == dma_chan1)
189 dma_chans[1] = dma_chan1;
190 else
191 dma_chans[1] = dma_chan2;
192
193 if (request_dma(dma_chans[0], dev->board_name))
194 goto no_dma;
195 dma->chan = dma_chans[0];
196 if (dma_chans[1] != dma_chans[0]) {
197 if (request_dma(dma_chans[1], dev->board_name))
198 goto no_dma;
199 }
200 dma->chan2 = dma_chans[1];
201
202 for (i = 0; i < n_desc; i++) {
203 desc = &dma->desc[i];
204 desc->chan = dma_chans[i];
205 desc->maxsize = maxsize;
206 desc->virt_addr = dma_alloc_coherent(dma->dev, desc->maxsize,
207 &desc->hw_addr,
208 GFP_KERNEL);
209 if (!desc->virt_addr)
210 goto no_dma;
211 comedi_isadma_set_mode(desc, dma_dir);
212 }
213
214 return dma;
215
216no_dma:
217 comedi_isadma_free(dma);
218 return NULL;
219}
220EXPORT_SYMBOL_GPL(comedi_isadma_alloc);
221
222/**
223 * comedi_isadma_free - free the ISA DMA
224 * @dma: the ISA DMA to free
225 */
226void comedi_isadma_free(struct comedi_isadma *dma)
227{
228 struct comedi_isadma_desc *desc;
229 int i;
230
231 if (!dma)
232 return;
233
234 if (dma->desc) {
235 for (i = 0; i < dma->n_desc; i++) {
236 desc = &dma->desc[i];
237 if (desc->virt_addr)
238 dma_free_coherent(dma->dev, desc->maxsize,
239 desc->virt_addr,
240 desc->hw_addr);
241 }
242 kfree(dma->desc);
243 }
244 if (dma->chan2 && dma->chan2 != dma->chan)
245 free_dma(dma->chan2);
246 if (dma->chan)
247 free_dma(dma->chan);
248 kfree(dma);
249}
250EXPORT_SYMBOL_GPL(comedi_isadma_free);
251
252static int __init comedi_isadma_init(void)
253{
254 return 0;
255}
256module_init(comedi_isadma_init);
257
258static void __exit comedi_isadma_exit(void)
259{
260}
261module_exit(comedi_isadma_exit);
262
263MODULE_AUTHOR("H Hartley Sweeten <hsweeten@visionengravers.com>");
264MODULE_DESCRIPTION("Comedi ISA DMA support");
265MODULE_LICENSE("GPL");