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Message-ID: <87b712f9-6191-4626-b031-0234379a166c@gmail.com>
Date: Tue, 11 Feb 2025 11:06:07 +0200
From: Matti Vaittinen <mazziesaccount@...il.com>
To: Jonathan Cameron <jic23@...nel.org>
Cc: Matti Vaittinen <matti.vaittinen@...rohmeurope.com>,
Lars-Peter Clausen <lars@...afoo.de>, Rob Herring <robh@...nel.org>,
Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor Dooley
<conor+dt@...nel.org>, Nuno Sa <nuno.sa@...log.com>,
David Lechner <dlechner@...libre.com>, linux-iio@...r.kernel.org,
devicetree@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 3/5] iio: adc: Support ROHM BD79124 ADC
On 08/02/2025 18:52, Jonathan Cameron wrote:
> On Wed, 5 Feb 2025 15:38:16 +0200
> Matti Vaittinen <mazziesaccount@...il.com> 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@...il.com>
>
> Hi Matti,
>
> Just a few really trivial comments though this wasn't my most thorough
> of reviews as ran out of time / energy today!
Thanks :) I appreciate the time and energy invested here :)
>
>> diff --git a/drivers/iio/adc/rohm-bd79124.c b/drivers/iio/adc/rohm-bd79124.c
>> new file mode 100644
>> index 000000000000..ea93762a24cc
>> --- /dev/null
>> +++ b/drivers/iio/adc/rohm-bd79124.c
>> @@ -0,0 +1,1149 @@
>
>
>> +static int bd79124_write_event_value(struct iio_dev *iio_dev,
>> + const struct iio_chan_spec *chan,
>> + enum iio_event_type type,
>> + enum iio_event_direction dir,
>> + enum iio_event_info info, int val,
>> + int val2)
>> +{
>> + struct bd79124_data *data = iio_priv(iio_dev);
>> + int reg;
>> +
>> + if (chan->channel >= BD79124_MAX_NUM_CHANNELS)
>> + return -EINVAL;
>> +
>> + switch (info) {
>> + case IIO_EV_INFO_VALUE:
>> + if (dir == IIO_EV_DIR_RISING) {
>> + guard(mutex)(&data->mutex);
>> +
>> + data->alarm_r_limit[chan->channel] = val;
>> + reg = BD79124_GET_HIGH_LIMIT_REG(chan->channel);
>> + } else if (dir == IIO_EV_DIR_FALLING) {
>> + guard(mutex)(&data->mutex);
>> +
>> + data->alarm_f_limit[chan->channel] = val;
>> + reg = BD79124_GET_LOW_LIMIT_REG(chan->channel);
>> + } else {
>> + return -EINVAL;
>> + }
>> + /*
>> + * We don't want to enable the alarm if it is not enabled or
>> + * if it is suppressed. In that case skip writing to the
>> + * register.
>> + */
>> + if (!(data->alarm_monitored[chan->channel] & BIT(dir)) ||
>> + data->alarm_suppressed[chan->channel] & BIT(dir))
>> + return 0;
>> +
>> + return bd79124_write_int_to_reg(data, reg, val);
>> +
>> + case IIO_EV_INFO_HYSTERESIS:
>> + reg = BD79124_GET_HYSTERESIS_REG(chan->channel);
>> + val >>= 3;
> Odd indent.
Oh, indeed. Thanks!
>> +
>> + return regmap_update_bits(data->map, reg, BD79124_MASK_HYSTERESIS,
>> + val);
>> + default:
>> + return -EINVAL;
>> + }
>> +}
>
>
>> +static void bd79124_re_enable_lo(struct bd79124_data *data, unsigned int channel)
>> +{
>> + int ret, evbit = BIT(IIO_EV_DIR_FALLING);
>> +
>> + if (!(data->alarm_suppressed[channel] & evbit))
>> + return;
>> +
>> + data->alarm_suppressed[channel] &= (~evbit);
>> +
>> + if (!(data->alarm_monitored[channel] & evbit))
>> + return;
>> +
>> + ret = bd79124_write_int_to_reg(data, BD79124_GET_LOW_LIMIT_REG(channel),
>> + data->alarm_f_limit[channel]);
>> + if (ret)
>> + dev_warn(data->dev, "Low limit enabling failed for channel%d\n",
>> + channel);
>> +}
>> +
>> +static void bd79124_re_enable_hi(struct bd79124_data *data, unsigned int channel)
>> +{
>> + int ret, evbit = BIT(IIO_EV_DIR_RISING);
>> +
>> + if (!(data->alarm_suppressed[channel] & evbit))
>> + return;
>> +
>> + data->alarm_suppressed[channel] &= (~evbit);
>> +
>> + if (!(data->alarm_monitored[channel] & evbit))
>> + return;
> This lot is very similar to the lo variant. Can we combine them or
> use some helper for both?
Initially I did this.
But the code looked a bit dull because the evbitm, alarm-limit array and
prints depend on the direction. Furthermore, the caller already knows
the direction (as the caller does also handle directions separately), so
doing:
foo(dir)
{
if (dir == bar)
...
else
...
}
...
if (dir == bar)
foo(dir);
else
foo(dir);
started to feel just a bit, meh. Hence I separated the stuff to own _lo
and _hi functions.
>> +
>> + ret = bd79124_write_int_to_reg(data, BD79124_GET_HIGH_LIMIT_REG(channel),
>> + data->alarm_r_limit[channel]);
>> + if (ret)
>> + dev_warn(data->dev, "High limit enabling failed for channel%d\n",
>> + channel);
>> +}
>
Yours,
-- Matti
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