diff options
author | H Hartley Sweeten <hsweeten@visionengravers.com> | 2013-06-04 02:05:08 (GMT) |
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committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2013-06-05 22:35:38 (GMT) |
commit | f0dc084e13145cd75bab09e08d7b7db84d09e319 (patch) | |
tree | 310d9f4c4637c553259f2eacb72d2fed28b11875 | |
parent | cac10bf92a0678bbc0c336e058f89a4a6e95aa96 (diff) | |
download | linux-fsl-qoriq-f0dc084e13145cd75bab09e08d7b7db84d09e319.tar.xz |
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>
-rw-r--r-- | drivers/staging/comedi/drivers/pcmda12.c | 32 |
1 files changed, 12 insertions, 20 deletions
diff --git a/drivers/staging/comedi/drivers/pcmda12.c b/drivers/staging/comedi/drivers/pcmda12.c index c61c2c1..2b62894 100644 --- a/drivers/staging/comedi/drivers/pcmda12.c +++ b/drivers/staging/comedi/drivers/pcmda12.c @@ -51,8 +51,6 @@ Configuration Options: #define CHANS 8 #define IOSIZE 16 -#define LSB(x) ((unsigned char)((x) & 0xff)) -#define MSB(x) ((unsigned char)((((unsigned short)(x))>>8) & 0xff)) #define LSB_PORT(chan) (dev->iobase + (chan)*2) #define MSB_PORT(chan) (LSB_PORT(chan)+1) @@ -90,31 +88,25 @@ static int pcmda12_ao_insn_write(struct comedi_device *dev, unsigned int *data) { struct pcmda12_private *devpriv = dev->private; + unsigned int chan = CR_CHAN(insn->chanspec); + unsigned int val = devpriv->ao_readback[chan]; int i; - int chan = CR_CHAN(insn->chanspec); - /* Writing a list of values to an AO channel is probably not - * very useful, but that's how the interface is defined. */ for (i = 0; i < insn->n; ++i) { - -/* /\* do this as one instruction?? *\/ */ -/* outw(data[i], LSB_PORT(chan)); */ - - /* Need to do this as two instructions due to 8-bit bus?? */ - /* first, load the low byte */ - outb(LSB(data[i]), LSB_PORT(chan)); - /* next, write the high byte */ - outb(MSB(data[i]), MSB_PORT(chan)); - - /* save shadow register */ - devpriv->ao_readback[chan] = data[i]; - + val = data[i]; + outb(val & 0xff, LSB_PORT(chan)); + outb((val >> 8) & 0xff, MSB_PORT(chan)); + + /* + * Initiate transfer if not in simultaneaous xfer + * mode by reading one of the AO registers. + */ if (!devpriv->simultaneous_xfer_mode) inb(LSB_PORT(chan)); } + devpriv->ao_readback[chan] = val; - /* return the number of samples written */ - return i; + return insn->n; } static int pcmda12_ao_insn_read(struct comedi_device *dev, |