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 */ |
24 | static 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 | |
51 | void 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 | } |
69 | EXPORT_SYMBOL_GPL(labpc_setup_dma); |
70 | |
71 | void 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 | } |
112 | EXPORT_SYMBOL_GPL(labpc_drain_dma); |
113 | |
114 | static 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 | |
128 | void 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 | } |
141 | EXPORT_SYMBOL_GPL(labpc_handle_dma_status); |
142 | |
143 | void 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 | } |
156 | EXPORT_SYMBOL_GPL(labpc_init_dma_chan); |
157 | |
158 | void 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 | } |
165 | EXPORT_SYMBOL_GPL(labpc_free_dma_chan); |
166 | |
167 | static int __init ni_labpc_isadma_init_module(void) |
168 | { |
169 | return 0; |
170 | } |
171 | module_init(ni_labpc_isadma_init_module); |
172 | |
173 | static void __exit ni_labpc_isadma_cleanup_module(void) |
174 | { |
175 | } |
176 | module_exit(ni_labpc_isadma_cleanup_module); |
177 | |
178 | MODULE_AUTHOR("Comedi https://www.comedi.org" ); |
179 | MODULE_DESCRIPTION("Comedi NI Lab-PC ISA DMA support" ); |
180 | MODULE_LICENSE("GPL" ); |
181 | |