1 // SPDX-License-Identifier: GPL-2.0+
3 * comedi/drivers/ni_labpc_isadma.c
4 * ISA DMA support for National Instruments Lab-PC series boards and
7 * Extracted from ni_labpc.c:
8 * Copyright (C) 2001-2003 Frank Mori Hess <fmhess@users.sourceforge.net>
11 #include <linux/module.h>
12 #include <linux/slab.h>
14 #include "../comedidev.h"
16 #include "comedi_isadma.h"
18 #include "ni_labpc_regs.h"
19 #include "ni_labpc_isadma.h"
21 /* size in bytes of dma buffer */
22 #define LABPC_ISADMA_BUFFER_SIZE 0xff00
24 /* utility function that suggests a dma transfer size in bytes */
25 static unsigned int labpc_suggest_transfer_size(struct comedi_device *dev,
26 struct comedi_subdevice *s,
27 unsigned int maxbytes)
29 struct comedi_cmd *cmd = &s->async->cmd;
30 unsigned int sample_size = comedi_bytes_per_sample(s);
34 if (cmd->convert_src == TRIG_TIMER)
35 freq = 1000000000 / cmd->convert_arg;
37 /* return some default value */
40 /* make buffer fill in no more than 1/3 second */
41 size = (freq / 3) * sample_size;
43 /* set a minimum and maximum size allowed */
46 else if (size < sample_size)
52 void labpc_setup_dma(struct comedi_device *dev, struct comedi_subdevice *s)
54 struct labpc_private *devpriv = dev->private;
55 struct comedi_isadma_desc *desc = &devpriv->dma->desc[0];
56 struct comedi_cmd *cmd = &s->async->cmd;
57 unsigned int sample_size = comedi_bytes_per_sample(s);
59 /* set appropriate size of transfer */
60 desc->size = labpc_suggest_transfer_size(dev, s, desc->maxsize);
61 if (cmd->stop_src == TRIG_COUNT &&
62 devpriv->count * sample_size < desc->size)
63 desc->size = devpriv->count * sample_size;
65 comedi_isadma_program(desc);
67 /* set CMD3 bits for caller to enable DMA and interrupt */
68 devpriv->cmd3 |= (CMD3_DMAEN | CMD3_DMATCINTEN);
70 EXPORT_SYMBOL_GPL(labpc_setup_dma);
72 void labpc_drain_dma(struct comedi_device *dev)
74 struct labpc_private *devpriv = dev->private;
75 struct comedi_isadma_desc *desc = &devpriv->dma->desc[0];
76 struct comedi_subdevice *s = dev->read_subdev;
77 struct comedi_async *async = s->async;
78 struct comedi_cmd *cmd = &async->cmd;
79 unsigned int max_samples = comedi_bytes_to_samples(s, desc->size);
81 unsigned int nsamples;
82 unsigned int leftover;
85 * residue is the number of bytes left to be done on the dma
86 * transfer. It should always be zero at this point unless
87 * the stop_src is set to external triggering.
89 residue = comedi_isadma_disable(desc->chan);
92 * Figure out how many samples to read for this transfer and
93 * how many will be stored for next time.
95 nsamples = max_samples - comedi_bytes_to_samples(s, residue);
96 if (cmd->stop_src == TRIG_COUNT) {
97 if (devpriv->count <= nsamples) {
98 nsamples = devpriv->count;
101 leftover = devpriv->count - nsamples;
102 if (leftover > max_samples)
103 leftover = max_samples;
105 devpriv->count -= nsamples;
107 leftover = max_samples;
109 desc->size = comedi_samples_to_bytes(s, leftover);
111 comedi_buf_write_samples(s, desc->virt_addr, nsamples);
113 EXPORT_SYMBOL_GPL(labpc_drain_dma);
115 static void handle_isa_dma(struct comedi_device *dev)
117 struct labpc_private *devpriv = dev->private;
118 struct comedi_isadma_desc *desc = &devpriv->dma->desc[0];
120 labpc_drain_dma(dev);
123 comedi_isadma_program(desc);
125 /* clear dma tc interrupt */
126 devpriv->write_byte(dev, 0x1, DMATC_CLEAR_REG);
129 void labpc_handle_dma_status(struct comedi_device *dev)
131 const struct labpc_boardinfo *board = dev->board_ptr;
132 struct labpc_private *devpriv = dev->private;
135 * if a dma terminal count of external stop trigger
138 if (devpriv->stat1 & STAT1_GATA0 ||
139 (board->is_labpc1200 && devpriv->stat2 & STAT2_OUTA1))
142 EXPORT_SYMBOL_GPL(labpc_handle_dma_status);
144 void labpc_init_dma_chan(struct comedi_device *dev, unsigned int dma_chan)
146 struct labpc_private *devpriv = dev->private;
148 /* only DMA channels 3 and 1 are valid */
149 if (dma_chan != 1 && dma_chan != 3)
152 /* DMA uses 1 buffer */
153 devpriv->dma = comedi_isadma_alloc(dev, 1, dma_chan, dma_chan,
154 LABPC_ISADMA_BUFFER_SIZE,
157 EXPORT_SYMBOL_GPL(labpc_init_dma_chan);
159 void labpc_free_dma_chan(struct comedi_device *dev)
161 struct labpc_private *devpriv = dev->private;
164 comedi_isadma_free(devpriv->dma);
166 EXPORT_SYMBOL_GPL(labpc_free_dma_chan);
168 static int __init ni_labpc_isadma_init_module(void)
172 module_init(ni_labpc_isadma_init_module);
174 static void __exit ni_labpc_isadma_cleanup_module(void)
177 module_exit(ni_labpc_isadma_cleanup_module);
179 MODULE_AUTHOR("Comedi https://www.comedi.org");
180 MODULE_DESCRIPTION("Comedi NI Lab-PC ISA DMA support");
181 MODULE_LICENSE("GPL");