Re: [PATCH v4 1/5] dt-bindings: misc: Add mikrobus-connector

From: "Michael Walle" <mwalle@kernel.org>
To: "Ayush Singh" <ayushdevel1325@gmail.com>,
	"open list" <linux-kernel@vger.kernel.org>
Cc: <jkridner@beagleboard.org>, <robertcnelson@beagleboard.org>,
	<lorforlinux@beagleboard.org>, "Rob Herring" <robh@kernel.org>,
	"Krzysztof Kozlowski" <krzysztof.kozlowski+dt@linaro.org>,
	"Conor Dooley" <conor+dt@kernel.org>,
	"Nishanth Menon" <nm@ti.com>,
	"Vignesh Raghavendra" <vigneshr@ti.com>,
	"Tero Kristo" <kristo@kernel.org>,
	"Derek Kiernan" <derek.kiernan@amd.com>,
	"Dragan Cvetic" <dragan.cvetic@amd.com>,
	"Arnd Bergmann" <arnd@arndb.de>,
	"Greg Kroah-Hartman" <gregkh@linuxfoundation.org>,
	"Vaishnav M A" <vaishnav.a@ti.com>,
	"Mark Brown" <broonie@kernel.org>,
	"Johan Hovold" <johan@kernel.org>,
	"Alex Elder" <elder@kernel.org>,
	"open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS"
	<devicetree@vger.kernel.org>,
	"moderated list:ARM/TEXAS INSTRUMENTS K3 ARCHITECTURE"
	<linux-arm-kernel@lists.infradead.org>,
	"open list:SPI SUBSYSTEM" <linux-spi@vger.kernel.org>,
	"moderated list:GREYBUS SUBSYSTEM" <greybus-dev@lists.linaro.org>,
	"Vaishnav M A" <vaishnav@beagleboard.org>
Subject: Re: [PATCH v4 1/5] dt-bindings: misc: Add mikrobus-connector
Date: Mon, 18 Mar 2024 13:22:39 +0100	[thread overview]
Message-ID: <CZWVF90JJO98.2M7ARQ9WMGC94@kernel.org> (raw)
In-Reply-To: <20240317193714.403132-2-ayushdevel1325@gmail.com>

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On Sun Mar 17, 2024 at 8:37 PM CET, Ayush Singh wrote:
> Add DT bindings for mikroBUS interface. MikroBUS is an open standard
> developed by MikroElektronika for connecting add-on boards to
> microcontrollers or microprocessors.
>
> mikroBUS is a connector and does not have a controller. Instead the
> software is responsible for identification of board and setting up /
> registering uart, spi, i2c, pwm and other buses. Thus it needs a way to
> get uart, spi, i2c, pwm and gpio controllers / adapters.
>
> A mikroBUS addon board is free to leave some of the pins unused which
> are marked as NC or Not Connected.
>
> Some of the pins might need to be configured as GPIOs deviating from their
> reserved purposes Eg: SHT15 Click where the SCL and SDA Pins need to be
> configured as GPIOs for the driver (drivers/hwmon/sht15.c) to work.
>
> For some add-on boards the driver may not take care of some additional
> signals like reset/wake-up/other. Eg: ENC28J60 click where the reset line
> (RST pin on the mikrobus port) needs to be pulled high.
>
> Here's the list of pins in mikroBUS connector:
> Analog - AN
> Reset - RST
> SPI Chip Select - CS
> SPI Clock - SCK
> SPI Master Input Slave Output - MISO
> SPI Master Output Slave Input - MOSI
> VCC-3.3V power - +3.3V
> Reference Ground - GND
> PWM - PWM output
> INT - Hardware Interrupt
> RX - UART Receive
> TX - UART Transmit
> SCL - I2C Clock
> SDA - I2C Data
> +5V - VCC-5V power
> GND - Reference Ground
>
> Additionally, some new mikroBUS boards contain 1-wire EEPROM that contains
> a manifest to describe the addon board to provide plug and play
> capabilities.
>
> Link: https://www.mikroe.com/mikrobus
> Link:
> https://download.mikroe.com/documents/standards/mikrobus/mikrobus-standard-specification-v200.pdf
> mikroBUS specification
> Link: https://www.mikroe.com/sht1x-click SHT15 Click
> Link: https://www.mikroe.com/eth-click ENC28J60 Click
> Link: https://www.mikroe.com/clickid ClickID
>
> Co-developed-by: Vaishnav M A <vaishnav@beagleboard.org>
> Signed-off-by: Vaishnav M A <vaishnav@beagleboard.org>
> Signed-off-by: Ayush Singh <ayushdevel1325@gmail.com>
> ---
>  .../connector/mikrobus-connector.yaml         | 113 ++++++++++++++++++

See also
https://lore.kernel.org/r/YmFo+EntwxIsco%2Ft@robh.at.kernel.org/

Looks like this proposal doesn't have the subnodes. How do you
attach a kernel driver to it's spi port for example? Only through
the manifest files?

-michael

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