staging: comedi: pcmda12: cleanup pcmda12_ao_insn_write()
Only the last value needs to be saved for readback. Remove the LSB and MSB macros. (*insn_write) functions should return an errno or the number of samples actually read. Change the final return to insn->n to make this clear. 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>
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@ -51,8 +51,6 @@ Configuration Options:
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#define CHANS 8
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#define IOSIZE 16
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#define LSB(x) ((unsigned char)((x) & 0xff))
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#define MSB(x) ((unsigned char)((((unsigned short)(x))>>8) & 0xff))
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#define LSB_PORT(chan) (dev->iobase + (chan)*2)
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#define MSB_PORT(chan) (LSB_PORT(chan)+1)
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@ -90,31 +88,25 @@ static int pcmda12_ao_insn_write(struct comedi_device *dev,
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unsigned int *data)
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{
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struct pcmda12_private *devpriv = dev->private;
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unsigned int chan = CR_CHAN(insn->chanspec);
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unsigned int val = devpriv->ao_readback[chan];
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int i;
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int chan = CR_CHAN(insn->chanspec);
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/* Writing a list of values to an AO channel is probably not
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* very useful, but that's how the interface is defined. */
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for (i = 0; i < insn->n; ++i) {
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val = data[i];
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outb(val & 0xff, LSB_PORT(chan));
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outb((val >> 8) & 0xff, MSB_PORT(chan));
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/* /\* do this as one instruction?? *\/ */
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/* outw(data[i], LSB_PORT(chan)); */
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/* Need to do this as two instructions due to 8-bit bus?? */
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/* first, load the low byte */
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outb(LSB(data[i]), LSB_PORT(chan));
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/* next, write the high byte */
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outb(MSB(data[i]), MSB_PORT(chan));
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/* save shadow register */
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devpriv->ao_readback[chan] = data[i];
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/*
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* Initiate transfer if not in simultaneaous xfer
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* mode by reading one of the AO registers.
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*/
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if (!devpriv->simultaneous_xfer_mode)
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inb(LSB_PORT(chan));
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}
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devpriv->ao_readback[chan] = val;
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/* return the number of samples written */
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return i;
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return insn->n;
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}
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static int pcmda12_ao_insn_read(struct comedi_device *dev,
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