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. > +} >