RE: [PATCH v2 2/4] iio: dac: ad3530r: Add ABI file for the AD3530R DAC

-----Original Message-----
From: Jonathan Cameron <jic23@kernel.org>
Sent: Friday, March 28, 2025 4:58 PM
To: Paller, Kim Seer <KimSeer.Paller@analog.com>
Cc: Lars-Peter Clausen <lars@metafoo.de>; Hennerich, Michael
[off-list ref]; Rob Herring [off-list ref]; Krzysztof
Kozlowski [off-list ref]; Conor Dooley [off-list ref]; linux-
iio@vger.kernel.org; linux-kernel@vger.kernel.org; devicetree@vger.kernel.org
Subject: Re: [PATCH v2 2/4] iio: dac: ad3530r: Add ABI file for the AD3530R
DAC

[External]

On Mon, 24 Mar 2025 19:22:56 +0800
Kim Seer Paller [off-list ref] wrote:

quoted

Define muxout_select and muxout_select_available sysfs interface for the
AD3530R and AD3531R DAC.

Signed-off-by: Kim Seer Paller <kimseer.paller@analog.com>
---
 .../ABI/testing/sysfs-bus-iio-dac-ad3530r          | 68 ++++++++++++++++++++++
 MAINTAINERS                                        |  7 +++
 2 files changed, 75 insertions(+)

diff --git a/Documentation/ABI/testing/sysfs-bus-iio-dac-ad3530r

b/Documentation/ABI/testing/sysfs-bus-iio-dac-ad3530r

quoted

new file mode 100644
index

0000000000000000000000000000000000000000..9d3126952fd1c5214afb89
5c4972dc4a891ed7d4

quoted

--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-bus-iio-dac-ad3530r

@@ -0,0 +1,68 @@
+What:		/sys/bus/iio/devices/iio:deviceX/muxout_select
+KernelVersion:
+Contact:	linux-iio@vger.kernel.org
+Description:
+		Selects which of the multiplexer's input signals will be
+		monitored on the MUX_OUT pin.

Hi Kim,

Do we have a use case where the monitoring would not be by an ADC attached
to the host CPU? (i.e. using a channel on an ADC that has it's own IIO driver)

No, we don’t have a use case without an ADC. I’ll proceed with implementing this
as a consumer of an ADC channel. Thanks

If no other use case, then support this as a consumer of an ADC channel from
another device with all these exposed as different channels when a read is
requested.
There are quite a few drivers doing this already.

The source vs sink thing may need to be done via labels as it isn't a concept
that maps directly to ADC channel characteristics.

If this is being routed to some external hardware monitoring then most like
this should be in device tree as doesn't make sense to switch dynamically in
any cases that I recall from previous similar drivers.

Jonathan

quoted

+		* powered_down - MUX_OUT pin is powered down. An 80kΩ

impedance

quoted

+				 can be seen at the MUX_OUT pin.
+		* vout0 - Voltage representation of VOUT0.
+		* iout0_source - Voltage representation of IOUT0 (source

mode).

quoted

+		* iout0_sink - Voltage representation of IOUT0 (sink mode).
+		* vout1 - Voltage representation of VOUT1.
+		* iout1_source - Voltage representation of IOUT1 (source

mode).

quoted

+		* iout1_sink - Voltage representation of IOUT1 (sink mode).
+		* vout2 - Voltage representation of VOUT2.
+		* iout2_source - Voltage representation of IOUT2 (source

mode).

quoted

+		* iout2_sink - Voltage representation of IOUT2 (sink mode).
+		* vout3 - Voltage representation of VOUT3
+		* iout3_source - Voltage representation of IOUT3 (source

mode).

quoted

+		* iout3_sink - Voltage representation of IOUT3 (sink mode).
+		* vout4 - Voltage representation of VOUT4.
+		* iout4_source - Voltage representation of IOUT4 (source

mode).

quoted

+		* iout4_sink - Voltage representation of IOUT4 (sink mode).
+		* vout5 - Voltage representation of VOUT5.
+		* iout5_source - Voltage representation of IOUT5 (source

mode).

quoted

+		* iout5_sink - Voltage representation of IOUT5 (sink mode).
+		* vout6 - Voltage representation of VOUT6.
+		* iout6_source - Voltage representation of IOUT6 (source

mode).

quoted

+		* iout6_sink - Voltage representation of IOUT6 (sink mode).
+		* vout7 - Voltage representation of VOUT7.
+		* iout7_source - Voltage representation of IOUT7 (source

mode).

quoted

+		* iout7_sink - Voltage representation of IOUT7 (sink mode).
+		* die_temp - Voltage representation of internal die

temperature.

quoted

+		* agnd - MUX_OUT pin internally tied to AGND.
+
+What:

	/sys/bus/iio/devices/iio:deviceX/muxout_select_available

quoted

+KernelVersion:
+Contact:	linux-iio@vger.kernel.org
+Description:
+		Reading this returns the valid values that can be written to the
+		muxout_select attribute:
+		* powered_down
+		* vout0
+		* iout0_source
+		* iout0_sink
+		* vout1
+		* iout1_source
+		* iout1_sink
+		* vout2
+		* iout2_source
+		* iout2_sink
+		* vout3
+		* iout3_source
+		* iout3_sink
+		* vout4
+		* iout4_source
+		* iout4_sink
+		* vout5
+		* iout5_source
+		* iout5_sink
+		* vout6
+		* iout6_source
+		* iout6_sink
+		* vout7
+		* iout7_source
+		* iout7_sink
+		* die_temp
+		* agnd

diff --git a/MAINTAINERS b/MAINTAINERS

index

ffdb3f21fc4fb35b349449afbb30fecd4fe72978..2d3c31c74594ca1934c67e7aad
0a179feeaa39bf 100644

quoted

--- a/MAINTAINERS
+++ b/MAINTAINERS

@@ -1289,6 +1289,13 @@ T:	git

git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net.git

quoted

 T:	git git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next.git
 F:	drivers/net/amt.c

+ANALOG DEVICES INC AD3530R DRIVER
+M:	Kim Seer Paller [off-list ref]
+L:	linux-iio@vger.kernel.org
+S:	Supported
+W:	https://ez.analog.com/linux-software-drivers
+F:	Documentation/ABI/testing/sysfs-bus-iio-dac-ad3530r
+
 ANALOG DEVICES INC AD3552R DRIVER
 M:	Nuno Sá [off-list ref]
 L:	linux-iio@vger.kernel.org