2 * comedi/drivers/ni_labpc_isadma.c
3 * ISA DMA support for National Instruments Lab-PC series boards and
6 * Extracted from ni_labpc.c:
7 * Copyright (C) 2001-2003 Frank Mori Hess <fmhess@users.sourceforge.net>
9 * This program is free software; you can redistribute it and/or modify
10 * it under the terms of the GNU General Public License as published by
11 * the Free Software Foundation; either version 2 of the License, or
12 * (at your option) any later version.
14 * This program is distributed in the hope that it will be useful,
15 * but WITHOUT ANY WARRANTY; without even the implied warranty of
16 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
17 * GNU General Public License for more details.
20 #include <linux/module.h>
21 #include <linux/slab.h>
23 #include "../comedidev.h"
25 #include "comedi_isadma.h"
27 #include "ni_labpc_regs.h"
28 #include "ni_labpc_isadma.h"
30 /* size in bytes of dma buffer */
31 #define LABPC_ISADMA_BUFFER_SIZE 0xff00
33 /* utility function that suggests a dma transfer size in bytes */
34 static unsigned int labpc_suggest_transfer_size(struct comedi_device *dev,
35 struct comedi_subdevice *s,
36 unsigned int maxbytes)
38 struct comedi_cmd *cmd = &s->async->cmd;
39 unsigned int sample_size = comedi_bytes_per_sample(s);
43 if (cmd->convert_src == TRIG_TIMER)
44 freq = 1000000000 / cmd->convert_arg;
46 /* return some default value */
49 /* make buffer fill in no more than 1/3 second */
50 size = (freq / 3) * sample_size;
52 /* set a minimum and maximum size allowed */
55 else if (size < sample_size)
61 void labpc_setup_dma(struct comedi_device *dev, struct comedi_subdevice *s)
63 struct labpc_private *devpriv = dev->private;
64 struct comedi_isadma_desc *desc = &devpriv->dma->desc[0];
65 struct comedi_cmd *cmd = &s->async->cmd;
66 unsigned int sample_size = comedi_bytes_per_sample(s);
68 /* set appropriate size of transfer */
69 desc->size = labpc_suggest_transfer_size(dev, s, desc->maxsize);
70 if (cmd->stop_src == TRIG_COUNT &&
71 devpriv->count * sample_size < desc->size)
72 desc->size = devpriv->count * sample_size;
74 comedi_isadma_program(desc);
76 /* set CMD3 bits for caller to enable DMA and interrupt */
77 devpriv->cmd3 |= (CMD3_DMAEN | CMD3_DMATCINTEN);
79 EXPORT_SYMBOL_GPL(labpc_setup_dma);
81 void labpc_drain_dma(struct comedi_device *dev)
83 struct labpc_private *devpriv = dev->private;
84 struct comedi_isadma_desc *desc = &devpriv->dma->desc[0];
85 struct comedi_subdevice *s = dev->read_subdev;
86 struct comedi_async *async = s->async;
87 struct comedi_cmd *cmd = &async->cmd;
88 unsigned int max_samples = comedi_bytes_to_samples(s, desc->size);
90 unsigned int nsamples;
91 unsigned int leftover;
94 * residue is the number of bytes left to be done on the dma
95 * transfer. It should always be zero at this point unless
96 * the stop_src is set to external triggering.
98 residue = comedi_isadma_disable(desc->chan);
101 * Figure out how many samples to read for this transfer and
102 * how many will be stored for next time.
104 nsamples = max_samples - comedi_bytes_to_samples(s, residue);
105 if (cmd->stop_src == TRIG_COUNT) {
106 if (devpriv->count <= nsamples) {
107 nsamples = devpriv->count;
110 leftover = devpriv->count - nsamples;
111 if (leftover > max_samples)
112 leftover = max_samples;
114 devpriv->count -= nsamples;
116 leftover = max_samples;
118 desc->size = comedi_samples_to_bytes(s, leftover);
120 comedi_buf_write_samples(s, desc->virt_addr, nsamples);
122 EXPORT_SYMBOL_GPL(labpc_drain_dma);
124 static void handle_isa_dma(struct comedi_device *dev)
126 struct labpc_private *devpriv = dev->private;
127 struct comedi_isadma_desc *desc = &devpriv->dma->desc[0];
129 labpc_drain_dma(dev);
132 comedi_isadma_program(desc);
134 /* clear dma tc interrupt */
135 devpriv->write_byte(dev, 0x1, DMATC_CLEAR_REG);
138 void labpc_handle_dma_status(struct comedi_device *dev)
140 const struct labpc_boardinfo *board = dev->board_ptr;
141 struct labpc_private *devpriv = dev->private;
144 * if a dma terminal count of external stop trigger
147 if (devpriv->stat1 & STAT1_GATA0 ||
148 (board->is_labpc1200 && devpriv->stat2 & STAT2_OUTA1))
151 EXPORT_SYMBOL_GPL(labpc_handle_dma_status);
153 void labpc_init_dma_chan(struct comedi_device *dev, unsigned int dma_chan)
155 struct labpc_private *devpriv = dev->private;
157 /* only DMA channels 3 and 1 are valid */
158 if (dma_chan != 1 && dma_chan != 3)
161 /* DMA uses 1 buffer */
162 devpriv->dma = comedi_isadma_alloc(dev, 1, dma_chan, dma_chan,
163 LABPC_ISADMA_BUFFER_SIZE,
166 EXPORT_SYMBOL_GPL(labpc_init_dma_chan);
168 void labpc_free_dma_chan(struct comedi_device *dev)
170 struct labpc_private *devpriv = dev->private;
173 comedi_isadma_free(devpriv->dma);
175 EXPORT_SYMBOL_GPL(labpc_free_dma_chan);
177 static int __init ni_labpc_isadma_init_module(void)
181 module_init(ni_labpc_isadma_init_module);
183 static void __exit ni_labpc_isadma_cleanup_module(void)
186 module_exit(ni_labpc_isadma_cleanup_module);
188 MODULE_AUTHOR("Comedi http://www.comedi.org");
189 MODULE_DESCRIPTION("Comedi NI Lab-PC ISA DMA support");
190 MODULE_LICENSE("GPL");