staging: comedi: comedi_isadma: introduce helper module for ISA DMA
Introduce a new helper module to consolidate all the ISA DMA code. This will allow removing the "depends on ISA_DMA_API" from the legacy drivers that can use DMA for async command support. This module is complete based on the various uses of ISA DMA in the comedi drivers. Signed-off-by: H Hartley Sweeten <hsweeten@visionengravers.com> Reviewed-by: Ian Abbott <abbotti@mev.co.uk> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
H Hartley Sweeten
Greg Kroah-Hartman
Родитель
5e5a21cf8e
Коммит
20a1ea7d6b
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@ -1262,6 +1262,9 @@ config COMEDI_DAS08
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tristate
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select COMEDI_8255
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config COMEDI_ISADMA
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tristate
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config COMEDI_NI_LABPC
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tristate
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select COMEDI_8255
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@ -3,6 +3,7 @@
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ccflags-$(CONFIG_COMEDI_DEBUG) := -DDEBUG
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# Comedi "helper" modules
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obj-$(CONFIG_COMEDI_ISADMA) += comedi_isadma.o
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# Comedi misc drivers
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obj-$(CONFIG_COMEDI_BOND) += comedi_bond.o
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@ -0,0 +1,262 @@
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/*
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* COMEDI ISA DMA support functions
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* Copyright (c) 2014 H Hartley Sweeten <hsweeten@visionengravers.com>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*/
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#include <linux/module.h>
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#include <linux/slab.h>
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#include <linux/delay.h>
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#include <linux/dma-mapping.h>
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#include <asm/dma.h>
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#include "../comedidev.h"
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#include "comedi_isadma.h"
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/**
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* comedi_isadma_program - program and enable an ISA DMA transfer
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* @desc: the ISA DMA cookie to program and enable
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*/
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void comedi_isadma_program(struct comedi_isadma_desc *desc)
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{
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unsigned long flags;
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flags = claim_dma_lock();
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clear_dma_ff(desc->chan);
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set_dma_mode(desc->chan, desc->mode);
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set_dma_addr(desc->chan, desc->hw_addr);
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set_dma_count(desc->chan, desc->size);
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enable_dma(desc->chan);
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release_dma_lock(flags);
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}
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EXPORT_SYMBOL_GPL(comedi_isadma_program);
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/**
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* comedi_isadma_disable - disable the ISA DMA channel
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* @dma_chan: the DMA channel to disable
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*
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* Returns the residue (remaining bytes) left in the DMA transfer.
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*/
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unsigned int comedi_isadma_disable(unsigned int dma_chan)
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{
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unsigned long flags;
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unsigned int residue;
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flags = claim_dma_lock();
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disable_dma(dma_chan);
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residue = get_dma_residue(dma_chan);
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release_dma_lock(flags);
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return residue;
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}
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EXPORT_SYMBOL_GPL(comedi_isadma_disable);
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/**
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* comedi_isadma_disable_on_sample - disable the ISA DMA channel
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* @dma_chan: the DMA channel to disable
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* @size: the sample size (in bytes)
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*
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* Returns the residue (remaining bytes) left in the DMA transfer.
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*/
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unsigned int comedi_isadma_disable_on_sample(unsigned int dma_chan,
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unsigned int size)
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{
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int stalled = 0;
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unsigned long flags;
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unsigned int residue;
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unsigned int new_residue;
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residue = comedi_isadma_disable(dma_chan);
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while (residue % size) {
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/* residue is a partial sample, enable DMA to allow more data */
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flags = claim_dma_lock();
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enable_dma(dma_chan);
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release_dma_lock(flags);
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udelay(2);
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new_residue = comedi_isadma_disable(dma_chan);
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/* is DMA stalled? */
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if (new_residue == residue) {
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stalled++;
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if (stalled > 10)
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break;
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}
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residue = new_residue;
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stalled = 0;
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}
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return residue;
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}
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EXPORT_SYMBOL_GPL(comedi_isadma_disable_on_sample);
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/**
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* comedi_isadma_poll - poll the current DMA transfer
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* @dma: the ISA DMA to poll
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*
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* Returns the position (in bytes) of the current DMA transfer.
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*/
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unsigned int comedi_isadma_poll(struct comedi_isadma *dma)
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{
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struct comedi_isadma_desc *desc = &dma->desc[dma->cur_dma];
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unsigned long flags;
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unsigned int result;
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unsigned int result1;
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flags = claim_dma_lock();
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clear_dma_ff(desc->chan);
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if (!isa_dma_bridge_buggy)
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disable_dma(desc->chan);
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result = get_dma_residue(desc->chan);
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/*
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* Read the counter again and choose higher value in order to
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* avoid reading during counter lower byte roll over if the
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* isa_dma_bridge_buggy is set.
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*/
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result1 = get_dma_residue(desc->chan);
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if (!isa_dma_bridge_buggy)
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enable_dma(desc->chan);
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release_dma_lock(flags);
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if (result < result1)
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result = result1;
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if (result >= desc->size || result == 0)
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return 0;
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else
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return desc->size - result;
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}
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EXPORT_SYMBOL_GPL(comedi_isadma_poll);
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/**
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* comedi_isadma_set_mode - set the ISA DMA transfer direction
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* @desc: the ISA DMA cookie to set
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* @dma_dir: the DMA direction
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*/
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void comedi_isadma_set_mode(struct comedi_isadma_desc *desc, char dma_dir)
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{
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desc->mode = (dma_dir == COMEDI_ISADMA_READ) ? DMA_MODE_READ
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: DMA_MODE_WRITE;
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}
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EXPORT_SYMBOL_GPL(comedi_isadma_set_mode);
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/**
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* comedi_isadma_alloc - allocate and initialize the ISA DMA
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* @dev: comedi_device struct
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* @n_desc: the number of cookies to allocate
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* @dma_chan: DMA channel for the first cookie
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* @dma_chan2: DMA channel for the second cookie
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* @maxsize: the size of the buffer to allocate for each cookie
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* @dma_dir: the DMA direction
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*
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* Returns the allocated and initialized ISA DMA or NULL if anything fails.
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*/
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struct comedi_isadma *comedi_isadma_alloc(struct comedi_device *dev,
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int n_desc, unsigned int dma_chan1,
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unsigned int dma_chan2,
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unsigned int maxsize, char dma_dir)
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{
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struct comedi_isadma *dma = NULL;
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struct comedi_isadma_desc *desc;
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unsigned int dma_chans[2];
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int i;
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if (n_desc < 1 || n_desc > 2)
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goto no_dma;
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dma = kzalloc(sizeof(*dma), GFP_KERNEL);
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if (!dma)
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goto no_dma;
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desc = kcalloc(n_desc, sizeof(*desc), GFP_KERNEL);
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if (!desc)
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goto no_dma;
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dma->desc = desc;
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dma->n_desc = n_desc;
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dma_chans[0] = dma_chan1;
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if (dma_chan2 == 0 || dma_chan2 == dma_chan1)
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dma_chans[1] = dma_chan1;
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else
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dma_chans[1] = dma_chan2;
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if (request_dma(dma_chans[0], dev->board_name))
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goto no_dma;
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dma->chan = dma_chans[0];
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if (dma_chans[1] != dma_chans[0]) {
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if (request_dma(dma_chans[1], dev->board_name))
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goto no_dma;
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}
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dma->chan2 = dma_chans[1];
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for (i = 0; i < n_desc; i++) {
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desc = &dma->desc[i];
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desc->chan = dma_chans[i];
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desc->maxsize = maxsize;
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desc->virt_addr = dma_alloc_coherent(NULL, desc->maxsize,
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&desc->hw_addr,
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GFP_KERNEL);
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if (!desc->virt_addr)
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goto no_dma;
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comedi_isadma_set_mode(desc, dma_dir);
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}
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return dma;
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no_dma:
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comedi_isadma_free(dma);
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return NULL;
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}
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EXPORT_SYMBOL_GPL(comedi_isadma_alloc);
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/**
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* comedi_isadma_free - free the ISA DMA
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* @dma: the ISA DMA to free
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*/
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void comedi_isadma_free(struct comedi_isadma *dma)
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{
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struct comedi_isadma_desc *desc;
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int i;
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if (!dma)
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return;
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if (dma->desc) {
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for (i = 0; i < dma->n_desc; i++) {
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desc = &dma->desc[i];
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if (desc->virt_addr)
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dma_free_coherent(NULL, desc->maxsize,
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desc->virt_addr, desc->hw_addr);
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}
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kfree(dma->desc);
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}
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if (dma->chan2 && dma->chan2 != dma->chan)
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free_dma(dma->chan2);
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if (dma->chan)
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free_dma(dma->chan);
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kfree(dma);
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}
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EXPORT_SYMBOL_GPL(comedi_isadma_free);
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static int __init comedi_isadma_init(void)
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{
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return 0;
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}
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module_init(comedi_isadma_init);
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static void __exit comedi_isadma_exit(void)
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{
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}
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module_exit(comedi_isadma_exit);
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MODULE_AUTHOR("H Hartley Sweeten <hsweeten@visionengravers.com>");
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MODULE_DESCRIPTION("Comedi ISA DMA support");
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MODULE_LICENSE("GPL");
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@ -0,0 +1,116 @@
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/*
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* COMEDI ISA DMA support functions
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* Copyright (c) 2014 H Hartley Sweeten <hsweeten@visionengravers.com>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*/
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#ifndef _COMEDI_ISADMA_H
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#define _COMEDI_ISADMA_H
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/*
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* These are used to avoid issues when <asm/dma.h> and the DMA_MODE_
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* defines are not available.
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*/
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#define COMEDI_ISADMA_READ 0
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#define COMEDI_ISADMA_WRITE 1
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/**
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* struct comedi_isadma_desc - cookie for ISA DMA
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* @virt_addr: virtual address of buffer
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* @hw_addr: hardware (bus) address of buffer
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* @chan: DMA channel
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* @maxsize: allocated size of buffer (in bytes)
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* @size: transfer size (in bytes)
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* @mode: DMA_MODE_READ or DMA_MODE_WRITE
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*/
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struct comedi_isadma_desc {
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void *virt_addr;
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dma_addr_t hw_addr;
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unsigned int chan;
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unsigned int maxsize;
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unsigned int size;
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char mode;
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};
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/**
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* struct comedi_isadma - ISA DMA data
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* @desc: cookie for each DMA buffer
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* @n_desc: the number of cookies
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* @cur_dma: the current cookie in use
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* @chan: the first DMA channel requested
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* @chan2: the second DMA channel requested
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*/
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struct comedi_isadma {
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struct comedi_isadma_desc *desc;
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int n_desc;
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int cur_dma;
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unsigned int chan;
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unsigned int chan2;
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};
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#if IS_ENABLED(CONFIG_ISA_DMA_API)
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void comedi_isadma_program(struct comedi_isadma_desc *);
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unsigned int comedi_isadma_disable(unsigned int dma_chan);
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unsigned int comedi_isadma_disable_on_sample(unsigned int dma_chan,
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unsigned int size);
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unsigned int comedi_isadma_poll(struct comedi_isadma *);
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void comedi_isadma_set_mode(struct comedi_isadma_desc *, char dma_dir);
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struct comedi_isadma *comedi_isadma_alloc(struct comedi_device *,
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int n_desc, unsigned int dma_chan1,
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unsigned int dma_chan2,
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unsigned int maxsize, char dma_dir);
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void comedi_isadma_free(struct comedi_isadma *);
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#else /* !IS_ENABLED(CONFIG_ISA_DMA_API) */
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static inline void comedi_isadma_program(struct comedi_isadma_desc *desc)
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{
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}
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static inline unsigned int comedi_isadma_disable(unsigned int dma_chan)
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{
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return 0;
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}
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static inline unsigned int
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comedi_isadma_disable_on_sample(unsigned int dma_chan, unsigned int size)
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{
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return 0;
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}
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static inline unsigned int comedi_isadma_poll(struct comedi_isadma *dma)
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{
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return 0;
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}
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static inline void comedi_isadma_set_mode(struct comedi_isadma_desc *desc,
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char dma_dir)
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{
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}
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static inline struct comedi_isadma *
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comedi_isadma_alloc(struct comedi_device *dev, int n_desc,
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unsigned int dma_chan1, unsigned int dma_chan2,
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unsigned int maxsize, char dma_dir)
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{
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return NULL;
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}
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static inline void comedi_isadma_free(struct comedi_isadma *dma)
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{
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}
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#endif /* !IS_ENABLED(CONFIG_ISA_DMA_API) */
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#endif /* #ifndef _COMEDI_ISADMA_H */
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