On Mon, 18 Dec 2023 17:00:10 +0100
Mårten Lindahl <martenli@xxxxxxxx> wrote:
> On 12/18/23 16:19, Mårten Lindahl wrote:
> > On 12/17/23 15:15, Jonathan Cameron wrote:
> >> On Fri, 15 Dec 2023 13:43:05 +0100
> >> Mårten Lindahl <marten.lindahl@xxxxxxxx> wrote:
> >>
> >>> The vcnl4040 proximity sensor defaults to 12 bit data resolution, but
> >>> the chip also supports 16 bit data resolution, which is called
> >>> proximity
> >>> high definition (PS_HD).
> >>>
> >>> Add read/write attribute for proximity resolution, and read attribute
> >>> for available proximity resolution values for the vcnl4040 chip.
> >>>
> >>> Signed-off-by: Mårten Lindahl <marten.lindahl@xxxxxxxx>
> > Hi Jonathan!
> >> I'll review this on basis the usecase is clear (see reply to cover
> >> letter)
> >
> > I'll skip this patch (see reply to cover letter comment)
> >
> > Your are right about the paired register manipulation. Better to
> > read/write byte instead of word.
>
> Hi Jonathan!
>
> I now remember why the register is read as a word (CONF1/CONF2). It is
> addressed as one 16 bit register where CONF1 is the low 8 bit field and
> CONF2 is the high bit field. It is the same address/code for both:
>
> Register PS_CONF1 - COMMAND CODE: 0x03_L (0x03 DATA BYTE LOW)
>
> Register PS_CONF2 - COMMAND CODE: 0x03_H (0x03 DATA BYTE HIGH)
>
> Where in my case (PS_CONF2->PS_HD[3] is the same as PS_CONF1[11])
Ouch. That's a horrible way to define a register map.
Jonathan
>
> Kind regards
>
> Mårten
>
> >
> > Kind regards
> >
> > Mårten
> >
> >>
> >> The manipulation of the CONF1 and CONF2 registers in a pair is rather
> >> odd given you
> >> only want to change one bit here.
> >>
> >> Why is that done?
> >>> ---
> >>> drivers/iio/light/vcnl4000.c | 87
> >>> +++++++++++++++++++++++++++++++++++++++++++-
> >>> 1 file changed, 85 insertions(+), 2 deletions(-)
> >>>
> >>> diff --git a/drivers/iio/light/vcnl4000.c
> >>> b/drivers/iio/light/vcnl4000.c
> >>> index fdf763a04b0b..2addff635b79 100644
> >>> --- a/drivers/iio/light/vcnl4000.c
> >>> +++ b/drivers/iio/light/vcnl4000.c
> >>> @@ -90,6 +90,7 @@
> >>> #define VCNL4040_PS_CONF1_PS_SHUTDOWN BIT(0)
> >>> #define VCNL4040_PS_CONF2_PS_IT GENMASK(3, 1) /* Proximity
> >>> integration time */
> >>> #define VCNL4040_CONF1_PS_PERS GENMASK(5, 4) /* Proximity
> >>> interrupt persistence setting */
> >>> +#define VCNL4040_PS_CONF2_PS_HD BIT(11) /* Proximity high
> >>> definition */
> >>> #define VCNL4040_PS_CONF2_PS_INT GENMASK(9, 8) /* Proximity
> >>> interrupt mode */
> >>> #define VCNL4040_PS_CONF3_MPS GENMASK(6, 5) /* Proximity
> >>> multi pulse number */
> >>> #define VCNL4040_PS_MS_LED_I GENMASK(10, 8) /* Proximity
> >>> current */
> >>> @@ -170,6 +171,11 @@ static const int vcnl4040_ps_calibbias_ua[][2] = {
> >>> {0, 200000},
> >>> };
> >>> +static const int vcnl4040_ps_resolutions[2] = {
> >>> + 12,
> >>> + 16
> >>> +};
> >>> +
> >>> static const int vcnl4040_als_persistence[] = {1, 2, 4, 8};
> >>> static const int vcnl4040_ps_persistence[] = {1, 2, 3, 4};
> >>> static const int vcnl4040_ps_oversampling_ratio[] = {1, 2, 4, 8};
> >>> @@ -880,6 +886,54 @@ static ssize_t
> >>> vcnl4040_write_ps_calibbias(struct vcnl4000_data *data, int val)
> >>> return ret;
> >>> }
> >>> +static ssize_t vcnl4040_read_ps_resolution(struct vcnl4000_data
> >>> *data, int *val, int *val2)
> >>> +{
> >>> + int ret;
> >>> +
> >>> + ret = i2c_smbus_read_word_data(data->client, VCNL4200_PS_CONF1);
> >> The field seems to be in PS_CONF2. So you are reading a word and I
> >> guess that
> >> gets you two registers. Can we not do a byte read to get just CONF2?
> >>> + if (ret < 0)
> >>> + return ret;
> >>> +
> >>> + ret = FIELD_GET(VCNL4040_PS_CONF2_PS_HD, ret);
> >>> + if (ret >= ARRAY_SIZE(vcnl4040_ps_resolutions))
> >>> + return -EINVAL;
> >>> +
> >>> + *val = vcnl4040_ps_resolutions[ret];
> >>> + *val2 = 0;
> >>> +
> >>> + return ret;
> >>> +}
> >>> +
> >>> +static ssize_t vcnl4040_write_ps_resolution(struct vcnl4000_data
> >>> *data, int val)
> >>> +{
> >>> + unsigned int i;
> >>> + int ret;
> >>> + u16 regval;
> >>> +
> >>> + for (i = 0; i < ARRAY_SIZE(vcnl4040_ps_resolutions); i++) {
> >>> + if (val == vcnl4040_ps_resolutions[i])
> >>> + break;
> >>> + }
> >>> +
> >>> + if (i >= ARRAY_SIZE(vcnl4040_ps_resolutions))
> >>> + return -EINVAL;
> >>> +
> >>> + mutex_lock(&data->vcnl4000_lock);
> >>> +
> >>> + ret = i2c_smbus_read_word_data(data->client, VCNL4200_PS_CONF1);
> >>> + if (ret < 0)
> >>> + goto out_unlock;
> >>> +
> >>> + regval = (ret & ~VCNL4040_PS_CONF2_PS_HD);
> >>> + regval |= FIELD_PREP(VCNL4040_PS_CONF2_PS_HD, i);
> >>> + ret = i2c_smbus_write_word_data(data->client, VCNL4200_PS_CONF1,
> >>> + regval);
> >>> +
> >>> +out_unlock:
> >>> + mutex_unlock(&data->vcnl4000_lock);
> >>> + return ret;
> >>> +}
> >> c),
