On 19/10/16 15:19, Eva Rachel Retuya wrote:
> Introduce defines for shifting and mask under the config register for
> better readability.
>
> Signed-off-by: Eva Rachel Retuya <eraretuya@xxxxxxxxx>
Worth sanity checking the resulting values when using macros (and reading
the docs closely!)
> ---
> Changes in v2:
> * Use GENMASK to generate both VTFS and CAPFS masks including offset,
> respectively.
> * Introduce helper variables for index calculation.
>
> drivers/staging/iio/cdc/ad7746.c | 36 ++++++++++++++++++++++--------------
> 1 file changed, 22 insertions(+), 14 deletions(-)
>
> diff --git a/drivers/staging/iio/cdc/ad7746.c b/drivers/staging/iio/cdc/ad7746.c
> index f41251c..5e9ceeb 100644
> --- a/drivers/staging/iio/cdc/ad7746.c
> +++ b/drivers/staging/iio/cdc/ad7746.c
> @@ -70,8 +70,12 @@
> #define AD7746_EXCSETUP_EXCLVL(x) (((x) & 0x3) << 0)
>
> /* Config Register Bit Designations (AD7746_REG_CFG) */
> -#define AD7746_CONF_VTFS(x) ((x) << 6)
> -#define AD7746_CONF_CAPFS(x) ((x) << 3)
> +#define AD7746_CONF_VTFS_SHIFT 6
> +#define AD7746_CONF_CAPFS_SHIFT 3
> +#define AD7746_CONF_VTFS_MASK(x) GENMASK(1, x)
> +#define AD7746_CONF_CAPFS_MASK(x) GENMASK(2, x)
These are only safe if x <= 1, 2
> +#define AD7746_CONF_VTFS(x) ((x) << AD7746_CONF_VTFS_SHIFT)
> +#define AD7746_CONF_CAPFS(x) ((x) << AD7746_CONF_CAPFS_SHIFT)
> #define AD7746_CONF_MODE_IDLE (0 << 0)
> #define AD7746_CONF_MODE_CONT_CONV (1 << 0)
> #define AD7746_CONF_MODE_SINGLE_CONV (2 << 0)
> @@ -217,15 +221,16 @@ static int ad7746_select_channel(struct iio_dev *indio_dev,
> struct iio_chan_spec const *chan)
> {
> struct ad7746_chip_info *chip = iio_priv(indio_dev);
> - int ret, delay;
> + int ret, delay, idx;
> u8 vt_setup, cap_setup;
>
> switch (chan->type) {
> case IIO_CAPACITANCE:
> cap_setup = (chan->address & 0xFF) | AD7746_CAPSETUP_CAPEN;
> vt_setup = chip->vt_setup & ~AD7746_VTSETUP_VTEN;
> - delay = ad7746_cap_filter_rate_table[(chip->config >> 3) &
> - 0x7][1];
> + idx = (chip->config >> AD7746_CONF_CAPFS_SHIFT) &
> + AD7746_CONF_CAPFS_MASK(0);
> + delay = ad7746_cap_filter_rate_table[idx][1];
>
> if (chip->capdac_set != chan->channel) {
> ret = i2c_smbus_write_byte_data(chip->client,
> @@ -246,8 +251,9 @@ static int ad7746_select_channel(struct iio_dev *indio_dev,
> case IIO_TEMP:
> vt_setup = (chan->address & 0xFF) | AD7746_VTSETUP_VTEN;
> cap_setup = chip->cap_setup & ~AD7746_CAPSETUP_CAPEN;
> - delay = ad7746_cap_filter_rate_table[(chip->config >> 6) &
> - 0x3][1];
> + idx = (chip->config >> AD7746_CONF_VTFS_SHIFT) &
> + AD7746_CONF_VTFS_MASK(0);
> + delay = ad7746_cap_filter_rate_table[idx][1];
> break;
> default:
> return -EINVAL;
> @@ -369,7 +375,7 @@ static int ad7746_store_cap_filter_rate_setup(struct ad7746_chip_info *chip,
> if (i >= ARRAY_SIZE(ad7746_cap_filter_rate_table))
> i = ARRAY_SIZE(ad7746_cap_filter_rate_table) - 1;
>
> - chip->config &= ~AD7746_CONF_CAPFS(0x7);
> + chip->config &= ~AD7746_CONF_CAPFS_MASK(AD7746_CONF_CAPFS_SHIFT);
> chip->config |= AD7746_CONF_CAPFS(i);
>
> return 0;
> @@ -387,7 +393,7 @@ static int ad7746_store_vt_filter_rate_setup(struct ad7746_chip_info *chip,
> if (i >= ARRAY_SIZE(ad7746_vt_filter_rate_table))
> i = ARRAY_SIZE(ad7746_vt_filter_rate_table) - 1;
>
> - chip->config &= ~AD7746_CONF_VTFS(0x3);
> + chip->config &= ~AD7746_CONF_VTFS_MASK(AD7746_CONF_VTFS_SHIFT);
This evaulates (I think) to GENMASK(1, 6);
Now this is gibberish (mask from bit 1 downto 6...)
To satisfy curiousity the implementation is:
GENMASK(h, l)
(((~0UL) << (l)) & (~0UL >> (BITS_PER_LONG - 1 - (h))))
so we have something like (0xFFFFFFFF << 6) & (0xFFFFFFFF >> (32 - 1 - 1))
0xFFFFFFC0 & ( 0x00000003) = 0. Not good.
> chip->config |= AD7746_CONF_VTFS(i);
>
> return 0;
> @@ -527,7 +533,7 @@ static int ad7746_read_raw(struct iio_dev *indio_dev,
> long mask)
> {
> struct ad7746_chip_info *chip = iio_priv(indio_dev);
> - int ret, delay;
> + int ret, delay, idx;
> u8 regval, reg;
>
> mutex_lock(&indio_dev->mlock);
> @@ -635,13 +641,15 @@ static int ad7746_read_raw(struct iio_dev *indio_dev,
> case IIO_CHAN_INFO_SAMP_FREQ:
> switch (chan->type) {
> case IIO_CAPACITANCE:
> - *val = ad7746_cap_filter_rate_table[
> - (chip->config >> 3) & 0x7][0];
> + idx = (chip->config >> AD7746_CONF_CAPFS_SHIFT) &
> + AD7746_CONF_CAPFS_MASK(0);
> + *val = ad7746_cap_filter_rate_table[idx][0];
> ret = IIO_VAL_INT;
> break;
> case IIO_VOLTAGE:
> - *val = ad7746_vt_filter_rate_table[
> - (chip->config >> 6) & 0x3][0];
> + idx = (chip->config >> AD7746_CONF_VTFS_SHIFT) &
> + AD7746_CONF_VTFS_MASK(0);
> + *val = ad7746_vt_filter_rate_table[idx][0];
> break;
> default:
> ret = -EINVAL;
>
--
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