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"
26 #include "comedi_fc.h"
28 #include "ni_labpc_regs.h"
29 #include "ni_labpc_isadma.h"
31 /* size in bytes of dma buffer */
32 #define LABPC_ISADMA_BUFFER_SIZE 0xff00
34 /* utility function that suggests a dma transfer size in bytes */
35 static unsigned int labpc_suggest_transfer_size(struct comedi_device *dev,
36 struct comedi_subdevice *s,
37 unsigned int maxbytes)
39 struct comedi_cmd *cmd = &s->async->cmd;
40 unsigned int sample_size = comedi_bytes_per_sample(s);
44 if (cmd->convert_src == TRIG_TIMER)
45 freq = 1000000000 / cmd->convert_arg;
47 /* return some default value */
50 /* make buffer fill in no more than 1/3 second */
51 size = (freq / 3) * sample_size;
53 /* set a minimum and maximum size allowed */
56 else if (size < sample_size)
62 void labpc_setup_dma(struct comedi_device *dev, struct comedi_subdevice *s)
64 struct labpc_private *devpriv = dev->private;
65 struct comedi_isadma_desc *desc = &devpriv->dma->desc[0];
66 struct comedi_cmd *cmd = &s->async->cmd;
67 unsigned int sample_size = comedi_bytes_per_sample(s);
69 /* set appropriate size of transfer */
70 desc->size = labpc_suggest_transfer_size(dev, s, desc->maxsize);
71 if (cmd->stop_src == TRIG_COUNT &&
72 devpriv->count * sample_size < desc->size)
73 desc->size = devpriv->count * sample_size;
75 comedi_isadma_program(desc);
77 /* set CMD3 bits for caller to enable DMA and interrupt */
78 devpriv->cmd3 |= (CMD3_DMAEN | CMD3_DMATCINTEN);
80 EXPORT_SYMBOL_GPL(labpc_setup_dma);
82 void labpc_drain_dma(struct comedi_device *dev)
84 struct labpc_private *devpriv = dev->private;
85 struct comedi_isadma_desc *desc = &devpriv->dma->desc[0];
86 struct comedi_subdevice *s = dev->read_subdev;
87 struct comedi_async *async = s->async;
88 struct comedi_cmd *cmd = &async->cmd;
89 unsigned int max_samples = comedi_bytes_to_samples(s, desc->size);
91 unsigned int nsamples;
92 unsigned int leftover;
95 * residue is the number of bytes left to be done on the dma
96 * transfer. It should always be zero at this point unless
97 * the stop_src is set to external triggering.
99 residue = comedi_isadma_disable(desc->chan);
102 * Figure out how many samples to read for this transfer and
103 * how many will be stored for next time.
105 nsamples = max_samples - comedi_bytes_to_samples(s, residue);
106 if (cmd->stop_src == TRIG_COUNT) {
107 if (devpriv->count <= nsamples) {
108 nsamples = devpriv->count;
111 leftover = devpriv->count - nsamples;
112 if (leftover > max_samples)
113 leftover = max_samples;
115 devpriv->count -= nsamples;
117 leftover = max_samples;
119 desc->size = comedi_samples_to_bytes(s, leftover);
121 comedi_buf_write_samples(s, desc->virt_addr, nsamples);
123 EXPORT_SYMBOL_GPL(labpc_drain_dma);
125 static void handle_isa_dma(struct comedi_device *dev)
127 struct labpc_private *devpriv = dev->private;
128 struct comedi_isadma_desc *desc = &devpriv->dma->desc[0];
130 labpc_drain_dma(dev);
133 comedi_isadma_program(desc);
135 /* clear dma tc interrupt */
136 devpriv->write_byte(dev, 0x1, DMATC_CLEAR_REG);
139 void labpc_handle_dma_status(struct comedi_device *dev)
141 const struct labpc_boardinfo *board = dev->board_ptr;
142 struct labpc_private *devpriv = dev->private;
145 * if a dma terminal count of external stop trigger
148 if (devpriv->stat1 & STAT1_GATA0 ||
149 (board->is_labpc1200 && devpriv->stat2 & STAT2_OUTA1))
152 EXPORT_SYMBOL_GPL(labpc_handle_dma_status);
154 void labpc_init_dma_chan(struct comedi_device *dev, unsigned int dma_chan)
156 struct labpc_private *devpriv = dev->private;
158 /* only DMA channels 3 and 1 are valid */
159 if (dma_chan != 1 && dma_chan != 3)
162 /* DMA uses 1 buffer */
163 devpriv->dma = comedi_isadma_alloc(dev, 1, dma_chan, dma_chan,
164 LABPC_ISADMA_BUFFER_SIZE,
167 EXPORT_SYMBOL_GPL(labpc_init_dma_chan);
169 void labpc_free_dma_chan(struct comedi_device *dev)
171 struct labpc_private *devpriv = dev->private;
174 comedi_isadma_free(devpriv->dma);
176 EXPORT_SYMBOL_GPL(labpc_free_dma_chan);
178 static int __init ni_labpc_isadma_init_module(void)
182 module_init(ni_labpc_isadma_init_module);
184 static void __exit ni_labpc_isadma_cleanup_module(void)
187 module_exit(ni_labpc_isadma_cleanup_module);
189 MODULE_AUTHOR("Comedi http://www.comedi.org");
190 MODULE_DESCRIPTION("Comedi NI Lab-PC ISA DMA support");
191 MODULE_LICENSE("GPL");