On Mon, 10 Mar 2025 14:56:47 +0200
Matti Vaittinen <mazziesaccount@xxxxxxxxx> wrote:
> The ROHM BD79124 is a 12-bit, 8-channel, SAR ADC. The ADC supports
> an automatic measurement mode, with an alarm interrupt for out-of-window
> measurements. The window is configurable for each channel.
>
> The I2C protocol for manual start of the measurement and data reading is
> somewhat peculiar. It requires the master to do clock stretching after
> sending the I2C slave-address until the slave has captured the data.
> Needless to say this is not well suopported by the I2C controllers.
>
> Thus the driver does not support the BD79124's manual measurement mode
> but implements the measurements using automatic measurement mode relying
> on the BD79124's ability of storing latest measurements into register.
>
> The driver does also support configuring the threshold events for
> detecting the out-of-window events.
>
> The BD79124 keeps asserting IRQ for as long as the measured voltage is
> out of the configured window. Thus the driver masks the received event
> for a fixed duration (1 second) when an event is handled. This prevents
> the user-space from choking on the events
>
> The ADC input pins can be also configured as general purpose outputs.
> Those pins which don't have corresponding ADC channel node in the
> device-tree will be controllable as GPO.
>
> Signed-off-by: Matti Vaittinen <mazziesaccount@xxxxxxxxx>
The comment below wins the Monday award for the trivial :)
> diff --git a/drivers/iio/adc/rohm-bd79124.c b/drivers/iio/adc/rohm-bd79124.c
> new file mode 100644
> index 000000000000..f63141daf5e2
> --- /dev/null
> +++ b/drivers/iio/adc/rohm-bd79124.c
> +static int bd79124_enable_event(struct bd79124_data *data,
> + enum iio_event_direction dir, unsigned int channel)
> +{
> + int dir_bit = BIT(dir);
> + int reg, ret;
> + u16 *limit;
> +
> + guard(mutex)(&data->mutex);
> + /* Set channel to be measured */
> + ret = bd79124_start_measurement(data, channel);
> + if (ret)
> + return ret;
> +
> + data->alarm_monitored[channel] |= dir_bit;
> +
> + /* Add the channel to the list of monitored channels */
> + ret = regmap_set_bits(data->map, BD79124_REG_ALERT_CH_SEL,
> + BIT(channel));
> + if (ret)
> + return ret;
> +
> + if (dir == IIO_EV_DIR_RISING) {
> + limit = &data->alarm_f_limit[channel];
> + reg = BD79124_GET_HIGH_LIMIT_REG(channel);
> + } else {
> + limit = &data->alarm_f_limit[channel];
> + reg = BD79124_GET_LOW_LIMIT_REG(channel);
> + }
> + /*
> + * Don't write the new limit to the hardware if we are in the
> + * rate-limit period. The timer which re-enables the event will set
> + * the limit.
> + */
> + if (!(data->alarm_suppressed[channel] & dir_bit)) {
> + ret = bd79124_write_int_to_reg(data, reg, *limit);
> + if (ret)
> + return ret;
> + }
> +
> + /*
> + * Enable comparator. Trust the regmap cache, no need to check
> + * if it was already enabled.
> + *
> + * We could do this in the hw-init, but there may be users who
> + * never enable alarms and for them it makes sense to not
> + * enable the comparator at probe.
> + */
> + return regmap_set_bits(data->map, BD79124_REG_GEN_CFG,
> + BD79124_MASK_DWC_EN);
> +
Stray blank line.
> +}
>
