[RFC PATCH 34/36] staging: comedi: amplc_dio200_common: convert driver to use the comedi_8254 module

[Ian Abbott]

On 20/02/15 23:05, H Hartley Sweeten wrote:
> Convert this driver to use the comedi_8254 module to provide the 8254 timer support.
>
> Add 'clock_src' and 'gate_src' members to the comedi_8254 data for convienence.
>
> Signed-off-by: H Hartley Sweeten <hsweeten at visionengravers.com>
> Cc: Ian Abbott <abbotti at mev.co.uk>
> Cc: Greg Kroah-Hartman <gregkh at linuxfoundation.org>
> ---
>   drivers/staging/comedi/Kconfig                     |   1 +
>   .../staging/comedi/drivers/amplc_dio200_common.c   | 263 ++++++---------------
>   drivers/staging/comedi/drivers/comedi_8254.h       |   4 +
>   3 files changed, 72 insertions(+), 196 deletions(-)
[snip]
> +static int dio200_subdev_8254_offset(struct comedi_device *dev,
> +				     struct comedi_subdevice *s)
>   {
> -	const struct dio200_board *board = dev->board_ptr;
> -	struct dio200_subdev_8254 *subpriv = s->private;
> +	struct comedi_8254 *i8254 = s->private;
>
> -	if (!board->has_clk_gat_sce)
> -		return -1;
> +	if (dev->mmio)
> +		return i8254->mmio - dev->mmio;
>
> -	return subpriv->gate_src[counter_number];
> +	return i8254->iobase - dev->iobase;
>   }

This will be wrong for the PCIe boards (board->is_pcie), where the 
registers are on 8-byte boundaries (regshift 3) instead of 1-byte 
boundaries (regshift 0).  The result needs to be shifted right by 3 for 
the PCIe boards.  The "offset" should be more of a "logical offset" as 
if the registers where on 1-byte boundaries.  I.e. it's the "logical 
offset" that determines which clock and gate selection registers to use 
(and the 'which' bit setting within the register values).

[snip]
>   static int dio200_subdev_8254_init(struct comedi_device *dev,
> @@ -686,28 +551,34 @@ static int dio200_subdev_8254_init(struct comedi_device *dev,
>   				   unsigned int offset)
>   {
>   	const struct dio200_board *board = dev->board_ptr;
> -	struct dio200_subdev_8254 *subpriv;
> -	unsigned int chan;
> +	struct comedi_8254 *i8254;
> +	unsigned int regshift;
> +	int chan;
>
> -	subpriv = comedi_alloc_spriv(s, sizeof(*subpriv));
> -	if (!subpriv)
> +	regshift = (board->is_pcie) ? 3 : 0;
> +
> +	if (dev->mmio)
> +		i8254 = comedi_8254_mm_init(dev->mmio + offset,
> +					    0, I8254_IO8, regshift);
> +	else
> +		i8254 = comedi_8254_init(dev->iobase + offset,
> +					 0, I8254_IO8, regshift);

The offsets to the 8254 will need to be shifted left by regshift, since 
the comedi_8254 module is reading and writing the registers itself 
rather than going through dio200_read8() and dio200_write8() which was 
previously responsible for the left shift.

-- 
-=( Ian Abbott @ MEV Ltd.    E-mail: <abbotti at mev.co.uk> )=-
-=(                          Web: http://www.mev.co.uk/  )=-