Support ROHM BD79112 ADC

From:		Matti Vaittinen <mazziesaccount-AT-gmail.com>
To:		Matti Vaittinen <mazziesaccount-AT-gmail.com>, Matti Vaittinen <matti.vaittinen-AT-fi.rohmeurope.com>
Subject:		[PATCH 0/3] Support ROHM BD79112 ADC
Date:		Tue, 02 Sep 2025 15:23:21 +0300
Message-ID:		<cover.1756813980.git.mazziesaccount@gmail.com>
Cc:		Jonathan Cameron <jic23-AT-kernel.org>, David Lechner <dlechner-AT-baylibre.com>, Nuno Sá <nuno.sa-AT-analog.com>, Andy Shevchenko <andy-AT-kernel.org>, Rob Herring <robh-AT-kernel.org>, Krzysztof Kozlowski <krzk+dt-AT-kernel.org>, Conor Dooley <conor+dt-AT-kernel.org>, Linus Walleij <linus.walleij-AT-linaro.org>, Bartosz Golaszewski <brgl-AT-bgdev.pl>, Matti Vaittinen <mazziesaccount-AT-gmail.com>, Marcelo Schmitt <marcelo.schmitt-AT-analog.com>, Javier Carrasco <javier.carrasco.cruz-AT-gmail.com>, Tobias Sperling <tobias.sperling-AT-softing.com>, Antoniu Miclaus <antoniu.miclaus-AT-analog.com>, Trevor Gamblin <tgamblin-AT-baylibre.com>, Esteban Blanc <eblanc-AT-baylibre.com>, Ramona Alexandra Nechita <ramona.nechita-AT-analog.com>, Thomas Bonnefille <thomas.bonnefille-AT-bootlin.com>, Hans de Goede <hansg-AT-kernel.org>, linux-iio-AT-vger.kernel.org, devicetree-AT-vger.kernel.org, linux-kernel-AT-vger.kernel.org, linux-gpio-AT-vger.kernel.org
Archive-link:		Article

Support ROHM BD79112 ADC/GPIO The ROHM BD79112 is a 12-bit, 32 channel SAR ADC / GPIO IC. Or, a "Signal Monitor Hub IC" as data-sheet describes it. Data sheet states the maximum sampling rate to be 1 MSPS, but achieving this would probably require the SPI and samples to be processed by something else but the CPU running Linux. This could work with the "SPI offloading" which has recently landed upstream - but I have no HW to test this so nothing fancy is implemented here. It's still worth mentioning if someone needs the speed and wants to try implementing it :) The SPI protocol is slightly peculiar. Accesses are done in 16-bit sequences, separated by releasing and re-aquiring the chip-select. Register write takes 1 such sequence. The 8-bit register data to write, is stored in the last 8 bits. The high 8 bits contain register address and an I/O-bit which needs to be set for register accesses. Register read consists of two 16-bit sequences (separated by chip-select). First sequence has again the register address and an IO bit in the high byte. Additionally, reads must have a 'read bit' set. The last 8 bits must be zero. The register data will be carried in the last 8 bits of the next 16-bit sequence while high bits in reply are zero. ADC data reading is similar to register reading except: - No R/W bit or I/O bit should be set. - Register address is replaced by channel number (0 - 31). - Reply data is carried in the 12 low bits (instead of 8 bits) of the reply sequence. The protocol is implemented using custom regmap read() and write() operations. Other than that, pretty standard device and driver. Matti Vaittinen (3): dt-bindings: iio: adc: ROHM BD79112 ADC/GPIO iio: adc: Support ROHM BD79112 ADC/GPIO MAINTAINERS: Support ROHM BD79112 ADC .../bindings/iio/adc/rohm,bd79112.yaml | 118 ++++ MAINTAINERS | 3 +- drivers/iio/adc/Kconfig | 10 + drivers/iio/adc/Makefile | 1 + drivers/iio/adc/rohm-bd79112.c | 542 ++++++++++++++++++ 5 files changed, 673 insertions(+), 1 deletion(-) create mode 100644 Documentation/devicetree/bindings/iio/adc/rohm,bd79112.yaml create mode 100644 drivers/iio/adc/rohm-bd79112.c base-commit: d1487b0b78720b86ec2a2ac7acc683ec90627e5b -- 2.51.0

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