1 // SPDX-License-Identifier: GPL-2.0+
3 * COMEDI ISA DMA support functions
4 * Copyright (c) 2014 H Hartley Sweeten <hsweeten@visionengravers.com>
7 #include <linux/module.h>
8 #include <linux/slab.h>
9 #include <linux/delay.h>
10 #include <linux/dma-mapping.h>
13 #include "../comedidev.h"
15 #include "comedi_isadma.h"
18 * comedi_isadma_program - program and enable an ISA DMA transfer
19 * @desc: the ISA DMA cookie to program and enable
21 void comedi_isadma_program(struct comedi_isadma_desc
*desc
)
25 flags
= claim_dma_lock();
26 clear_dma_ff(desc
->chan
);
27 set_dma_mode(desc
->chan
, desc
->mode
);
28 set_dma_addr(desc
->chan
, desc
->hw_addr
);
29 set_dma_count(desc
->chan
, desc
->size
);
30 enable_dma(desc
->chan
);
31 release_dma_lock(flags
);
33 EXPORT_SYMBOL_GPL(comedi_isadma_program
);
36 * comedi_isadma_disable - disable the ISA DMA channel
37 * @dma_chan: the DMA channel to disable
39 * Returns the residue (remaining bytes) left in the DMA transfer.
41 unsigned int comedi_isadma_disable(unsigned int dma_chan
)
46 flags
= claim_dma_lock();
47 disable_dma(dma_chan
);
48 residue
= get_dma_residue(dma_chan
);
49 release_dma_lock(flags
);
53 EXPORT_SYMBOL_GPL(comedi_isadma_disable
);
56 * comedi_isadma_disable_on_sample - disable the ISA DMA channel
57 * @dma_chan: the DMA channel to disable
58 * @size: the sample size (in bytes)
60 * Returns the residue (remaining bytes) left in the DMA transfer.
62 unsigned int comedi_isadma_disable_on_sample(unsigned int dma_chan
,
68 unsigned int new_residue
;
70 residue
= comedi_isadma_disable(dma_chan
);
71 while (residue
% size
) {
72 /* residue is a partial sample, enable DMA to allow more data */
73 flags
= claim_dma_lock();
75 release_dma_lock(flags
);
78 new_residue
= comedi_isadma_disable(dma_chan
);
81 if (new_residue
== residue
) {
86 residue
= new_residue
;
92 EXPORT_SYMBOL_GPL(comedi_isadma_disable_on_sample
);
95 * comedi_isadma_poll - poll the current DMA transfer
96 * @dma: the ISA DMA to poll
98 * Returns the position (in bytes) of the current DMA transfer.
100 unsigned int comedi_isadma_poll(struct comedi_isadma
*dma
)
102 struct comedi_isadma_desc
*desc
= &dma
->desc
[dma
->cur_dma
];
105 unsigned int result1
;
107 flags
= claim_dma_lock();
108 clear_dma_ff(desc
->chan
);
109 if (!isa_dma_bridge_buggy
)
110 disable_dma(desc
->chan
);
111 result
= get_dma_residue(desc
->chan
);
113 * Read the counter again and choose higher value in order to
114 * avoid reading during counter lower byte roll over if the
115 * isa_dma_bridge_buggy is set.
117 result1
= get_dma_residue(desc
->chan
);
118 if (!isa_dma_bridge_buggy
)
119 enable_dma(desc
->chan
);
120 release_dma_lock(flags
);
122 if (result
< result1
)
124 if (result
>= desc
->size
|| result
== 0)
126 return desc
->size
- result
;
128 EXPORT_SYMBOL_GPL(comedi_isadma_poll
);
131 * comedi_isadma_set_mode - set the ISA DMA transfer direction
132 * @desc: the ISA DMA cookie to set
133 * @dma_dir: the DMA direction
135 void comedi_isadma_set_mode(struct comedi_isadma_desc
*desc
, char dma_dir
)
137 desc
->mode
= (dma_dir
== COMEDI_ISADMA_READ
) ? DMA_MODE_READ
140 EXPORT_SYMBOL_GPL(comedi_isadma_set_mode
);
143 * comedi_isadma_alloc - allocate and initialize the ISA DMA
144 * @dev: comedi_device struct
145 * @n_desc: the number of cookies to allocate
146 * @dma_chan: DMA channel for the first cookie
147 * @dma_chan2: DMA channel for the second cookie
148 * @maxsize: the size of the buffer to allocate for each cookie
149 * @dma_dir: the DMA direction
151 * Returns the allocated and initialized ISA DMA or NULL if anything fails.
153 struct comedi_isadma
*comedi_isadma_alloc(struct comedi_device
*dev
,
154 int n_desc
, unsigned int dma_chan1
,
155 unsigned int dma_chan2
,
156 unsigned int maxsize
, char dma_dir
)
158 struct comedi_isadma
*dma
= NULL
;
159 struct comedi_isadma_desc
*desc
;
160 unsigned int dma_chans
[2];
163 if (n_desc
< 1 || n_desc
> 2)
166 dma
= kzalloc(sizeof(*dma
), GFP_KERNEL
);
170 desc
= kcalloc(n_desc
, sizeof(*desc
), GFP_KERNEL
);
174 dma
->n_desc
= n_desc
;
176 dma
->dev
= dev
->hw_dev
;
178 /* Fall back to using the "class" device. */
181 /* Need 24-bit mask for ISA DMA. */
182 if (dma_coerce_mask_and_coherent(dev
->class_dev
,
186 dma
->dev
= dev
->class_dev
;
189 dma_chans
[0] = dma_chan1
;
190 if (dma_chan2
== 0 || dma_chan2
== dma_chan1
)
191 dma_chans
[1] = dma_chan1
;
193 dma_chans
[1] = dma_chan2
;
195 if (request_dma(dma_chans
[0], dev
->board_name
))
197 dma
->chan
= dma_chans
[0];
198 if (dma_chans
[1] != dma_chans
[0]) {
199 if (request_dma(dma_chans
[1], dev
->board_name
))
202 dma
->chan2
= dma_chans
[1];
204 for (i
= 0; i
< n_desc
; i
++) {
205 desc
= &dma
->desc
[i
];
206 desc
->chan
= dma_chans
[i
];
207 desc
->maxsize
= maxsize
;
208 desc
->virt_addr
= dma_alloc_coherent(dma
->dev
, desc
->maxsize
,
211 if (!desc
->virt_addr
)
213 comedi_isadma_set_mode(desc
, dma_dir
);
219 comedi_isadma_free(dma
);
222 EXPORT_SYMBOL_GPL(comedi_isadma_alloc
);
225 * comedi_isadma_free - free the ISA DMA
226 * @dma: the ISA DMA to free
228 void comedi_isadma_free(struct comedi_isadma
*dma
)
230 struct comedi_isadma_desc
*desc
;
237 for (i
= 0; i
< dma
->n_desc
; i
++) {
238 desc
= &dma
->desc
[i
];
240 dma_free_coherent(dma
->dev
, desc
->maxsize
,
246 if (dma
->chan2
&& dma
->chan2
!= dma
->chan
)
247 free_dma(dma
->chan2
);
252 EXPORT_SYMBOL_GPL(comedi_isadma_free
);
254 static int __init
comedi_isadma_init(void)
258 module_init(comedi_isadma_init
);
260 static void __exit
comedi_isadma_exit(void)
263 module_exit(comedi_isadma_exit
);
265 MODULE_AUTHOR("H Hartley Sweeten <hsweeten@visionengravers.com>");
266 MODULE_DESCRIPTION("Comedi ISA DMA support");
267 MODULE_LICENSE("GPL");