1// SPDX-License-Identifier: GPL-2.0+
2/*
3 * comedi/drivers/ni_labpc_isadma.c
4 * ISA DMA support for National Instruments Lab-PC series boards and
5 * compatibles.
6 *
7 * Extracted from ni_labpc.c:
8 * Copyright (C) 2001-2003 Frank Mori Hess <fmhess@users.sourceforge.net>
9 */
10
11#include <linux/module.h>
12#include <linux/slab.h>
13#include <linux/comedi/comedidev.h>
14#include <linux/comedi/comedi_isadma.h>
15
16#include "ni_labpc.h"
17#include "ni_labpc_regs.h"
18#include "ni_labpc_isadma.h"
19
20/* size in bytes of dma buffer */
21#define LABPC_ISADMA_BUFFER_SIZE 0xff00
22
23/* utility function that suggests a dma transfer size in bytes */
24static unsigned int labpc_suggest_transfer_size(struct comedi_device *dev,
25 struct comedi_subdevice *s,
26 unsigned int maxbytes)
27{
28 struct comedi_cmd *cmd = &s->async->cmd;
29 unsigned int sample_size = comedi_bytes_per_sample(s);
30 unsigned int size;
31 unsigned int freq;
32
33 if (cmd->convert_src == TRIG_TIMER)
34 freq = 1000000000 / cmd->convert_arg;
35 else
36 /* return some default value */
37 freq = 0xffffffff;
38
39 /* make buffer fill in no more than 1/3 second */
40 size = (freq / 3) * sample_size;
41
42 /* set a minimum and maximum size allowed */
43 if (size > maxbytes)
44 size = maxbytes;
45 else if (size < sample_size)
46 size = sample_size;
47
48 return size;
49}
50
51void labpc_setup_dma(struct comedi_device *dev, struct comedi_subdevice *s)
52{
53 struct labpc_private *devpriv = dev->private;
54 struct comedi_isadma_desc *desc = &devpriv->dma->desc[0];
55 struct comedi_cmd *cmd = &s->async->cmd;
56 unsigned int sample_size = comedi_bytes_per_sample(s);
57
58 /* set appropriate size of transfer */
59 desc->size = labpc_suggest_transfer_size(dev, s, maxbytes: desc->maxsize);
60 if (cmd->stop_src == TRIG_COUNT &&
61 devpriv->count * sample_size < desc->size)
62 desc->size = devpriv->count * sample_size;
63
64 comedi_isadma_program(desc);
65
66 /* set CMD3 bits for caller to enable DMA and interrupt */
67 devpriv->cmd3 |= (CMD3_DMAEN | CMD3_DMATCINTEN);
68}
69EXPORT_SYMBOL_GPL(labpc_setup_dma);
70
71void labpc_drain_dma(struct comedi_device *dev)
72{
73 struct labpc_private *devpriv = dev->private;
74 struct comedi_isadma_desc *desc = &devpriv->dma->desc[0];
75 struct comedi_subdevice *s = dev->read_subdev;
76 struct comedi_async *async = s->async;
77 struct comedi_cmd *cmd = &async->cmd;
78 unsigned int max_samples = comedi_bytes_to_samples(s, nbytes: desc->size);
79 unsigned int residue;
80 unsigned int nsamples;
81 unsigned int leftover;
82
83 /*
84 * residue is the number of bytes left to be done on the dma
85 * transfer. It should always be zero at this point unless
86 * the stop_src is set to external triggering.
87 */
88 residue = comedi_isadma_disable(dma_chan: desc->chan);
89
90 /*
91 * Figure out how many samples to read for this transfer and
92 * how many will be stored for next time.
93 */
94 nsamples = max_samples - comedi_bytes_to_samples(s, nbytes: residue);
95 if (cmd->stop_src == TRIG_COUNT) {
96 if (devpriv->count <= nsamples) {
97 nsamples = devpriv->count;
98 leftover = 0;
99 } else {
100 leftover = devpriv->count - nsamples;
101 if (leftover > max_samples)
102 leftover = max_samples;
103 }
104 devpriv->count -= nsamples;
105 } else {
106 leftover = max_samples;
107 }
108 desc->size = comedi_samples_to_bytes(s, nsamples: leftover);
109
110 comedi_buf_write_samples(s, data: desc->virt_addr, nsamples);
111}
112EXPORT_SYMBOL_GPL(labpc_drain_dma);
113
114static void handle_isa_dma(struct comedi_device *dev)
115{
116 struct labpc_private *devpriv = dev->private;
117 struct comedi_isadma_desc *desc = &devpriv->dma->desc[0];
118
119 labpc_drain_dma(dev);
120
121 if (desc->size)
122 comedi_isadma_program(desc);
123
124 /* clear dma tc interrupt */
125 devpriv->write_byte(dev, 0x1, DMATC_CLEAR_REG);
126}
127
128void labpc_handle_dma_status(struct comedi_device *dev)
129{
130 const struct labpc_boardinfo *board = dev->board_ptr;
131 struct labpc_private *devpriv = dev->private;
132
133 /*
134 * if a dma terminal count of external stop trigger
135 * has occurred
136 */
137 if (devpriv->stat1 & STAT1_GATA0 ||
138 (board->is_labpc1200 && devpriv->stat2 & STAT2_OUTA1))
139 handle_isa_dma(dev);
140}
141EXPORT_SYMBOL_GPL(labpc_handle_dma_status);
142
143void labpc_init_dma_chan(struct comedi_device *dev, unsigned int dma_chan)
144{
145 struct labpc_private *devpriv = dev->private;
146
147 /* only DMA channels 3 and 1 are valid */
148 if (dma_chan != 1 && dma_chan != 3)
149 return;
150
151 /* DMA uses 1 buffer */
152 devpriv->dma = comedi_isadma_alloc(dev, n_desc: 1, dma_chan1: dma_chan, dma_chan2: dma_chan,
153 LABPC_ISADMA_BUFFER_SIZE,
154 COMEDI_ISADMA_READ);
155}
156EXPORT_SYMBOL_GPL(labpc_init_dma_chan);
157
158void labpc_free_dma_chan(struct comedi_device *dev)
159{
160 struct labpc_private *devpriv = dev->private;
161
162 if (devpriv)
163 comedi_isadma_free(dma: devpriv->dma);
164}
165EXPORT_SYMBOL_GPL(labpc_free_dma_chan);
166
167static int __init ni_labpc_isadma_init_module(void)
168{
169 return 0;
170}
171module_init(ni_labpc_isadma_init_module);
172
173static void __exit ni_labpc_isadma_cleanup_module(void)
174{
175}
176module_exit(ni_labpc_isadma_cleanup_module);
177
178MODULE_AUTHOR("Comedi https://www.comedi.org");
179MODULE_DESCRIPTION("Comedi NI Lab-PC ISA DMA support");
180MODULE_LICENSE("GPL");
181

source code of linux/drivers/comedi/drivers/ni_labpc_isadma.c