diff options
author | H Hartley Sweeten <hartleys@visionengravers.com> | 2012-08-16 19:54:32 -0700 |
---|---|---|
committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2012-08-17 08:17:36 -0700 |
commit | aee815b53bca1cfa092ecd742fc59512b8030336 (patch) | |
tree | 53c6cf80e146d5997347fe47f8f63b02886635fd /drivers/staging | |
parent | b9616b18c1dbbc3bfad9c1801fb96f41c26449e2 (diff) |
staging: comedi: cb_pcimdda: cleanup the analog out read/write
Use the register map define to work out the i/o address.
Cleanup the comments about the simultaneous transfer mode for
the analog outputs.
Change the return to 'insn->n', the comedi core expects the return
to be the number of data elements used. Technically the 'i' value
is correct but 'insn->n' just makes it clearer.
Signed-off-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Cc: Ian Abbott <abbotti@mev.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/staging')
-rw-r--r-- | drivers/staging/comedi/drivers/cb_pcimdda.c | 63 |
1 files changed, 26 insertions, 37 deletions
diff --git a/drivers/staging/comedi/drivers/cb_pcimdda.c b/drivers/staging/comedi/drivers/cb_pcimdda.c index a5e055f0a5ff..350c8078cded 100644 --- a/drivers/staging/comedi/drivers/cb_pcimdda.c +++ b/drivers/staging/comedi/drivers/cb_pcimdda.c @@ -110,62 +110,51 @@ static int cb_pcimdda_ao_winsn(struct comedi_device *dev, unsigned int *data) { struct cb_pcimdda_private *devpriv = dev->private; + unsigned int chan = CR_CHAN(insn->chanspec); + unsigned long offset = dev->iobase + PCIMDDA_DA_CHAN(chan); + unsigned int val = 0; int i; - int chan = CR_CHAN(insn->chanspec); - unsigned long offset = dev->iobase + chan * 2; - /* 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++) { - /* first, load the low byte */ - outb((char)(data[i] & 0x00ff), offset); - /* next, write the high byte -- only after this is written is - the channel voltage updated in the DAC, unless - we're in simultaneous xfer mode (jumper on card) - then a rinsn is necessary to actually update the DAC -- - see cb_pcimdda_ao_rinsn() below... */ - outb((char)(data[i] >> 8 & 0x00ff), offset + 1); - - /* for testing only.. the actual rinsn SHOULD do an inw! - (see the stuff about simultaneous XFER mode on this board) */ - devpriv->ao_readback[chan] = data[i]; + val = data[i]; + + /* + * Write the LSB then MSB. + * + * If the simultaneous xfer mode is selected by the + * jumper on the card, a read instruction is needed + * in order to initiate the simultaneous transfer. + * Otherwise, the DAC will be updated when the MSB + * is written. + */ + outb(val & 0x00ff, offset); + outb((val >> 8) & 0x00ff, offset + 1); } - /* return the number of samples read/written */ - return i; -} + /* Cache the last value for readback */ + devpriv->ao_readback[chan] = val; -/* AO subdevices should have a read insn as well as a write insn. + return insn->n; +} - Usually this means copying a value stored in devpriv->ao_readback. - However, since this board has this jumper setting called "Simultaneous - Xfer mode" (off by default), we will support it. Simultaneaous xfer - mode is accomplished by loading ALL the values you want for AO in all the - channels, then READing off one of the AO registers to initiate the - instantaneous simultaneous update of all DAC outputs, which makes - all AO channels update simultaneously. This is useful for some control - applications, I would imagine. -*/ static int cb_pcimdda_ao_rinsn(struct comedi_device *dev, struct comedi_subdevice *s, struct comedi_insn *insn, unsigned int *data) { struct cb_pcimdda_private *devpriv = dev->private; - int i; int chan = CR_CHAN(insn->chanspec); + unsigned long offset = dev->iobase + PCIMDDA_DA_CHAN(chan); + int i; for (i = 0; i < insn->n; i++) { - inw(dev->iobase + chan * 2); - /* - * should I set data[i] to the result of the actual read - * on the register or the cached unsigned int in - * devpriv->ao_readback[]? - */ + /* Initiate the simultaneous transfer */ + inw(offset); + data[i] = devpriv->ao_readback[chan]; } - return i; + return insn->n; } static struct pci_dev *cb_pcimdda_probe(struct comedi_device *dev, |