Re: [PATCH v4 1/5] dt-bindings: misc: Add mikrobus-connector
From: Ayush Singh
Date: Fri Mar 22 2024 - 14:23:41 EST
On 3/18/24 01:07, 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@xxxxxxxxxxxxxxx>
Signed-off-by: Vaishnav M A <vaishnav@xxxxxxxxxxxxxxx>
Signed-off-by: Ayush Singh <ayushdevel1325@xxxxxxxxx>
---
.../connector/mikrobus-connector.yaml | 113 ++++++++++++++++++
MAINTAINERS | 6 +
2 files changed, 119 insertions(+)
create mode 100644 Documentation/devicetree/bindings/connector/mikrobus-connector.yaml
diff --git a/Documentation/devicetree/bindings/connector/mikrobus-connector.yaml b/Documentation/devicetree/bindings/connector/mikrobus-connector.yaml
new file mode 100644
index 000000000000..ee3736add41c
--- /dev/null
+++ b/Documentation/devicetree/bindings/connector/mikrobus-connector.yaml
@@ -0,0 +1,113 @@
+# SPDX-License-Identifier: GPL-2.0 OR BSD-2-Clause
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/connector/mikrobus-connector.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: mikroBUS add-on board socket
+
+maintainers:
+ - Ayush Singh <ayushdevel1325@xxxxxxxxx>
+
+properties:
+ compatible:
+ const: mikrobus-connector
+
+ pinctrl-0: true
+ pinctrl-1: true
+ pinctrl-2: true
+ pinctrl-3: true
+ pinctrl-4: true
+ pinctrl-5: true
+ pinctrl-6: true
+ pinctrl-7: true
+ pinctrl-8: true
+
+ pinctrl-names:
+ items:
+ - const: default
+ - const: pwm_default
+ - const: pwm_gpio
+ - const: uart_default
+ - const: uart_gpio
+ - const: i2c_default
+ - const: i2c_gpio
+ - const: spi_default
+ - const: spi_gpio
+
+ mikrobus-gpios:
+ minItems: 11
+ maxItems: 12
+
+ i2c-adapter:
+ description: i2c adapter attached to the mikrobus socket.
+ $ref: /schemas/types.yaml#/definitions/phandle
+
+ spi-controller:
+ description: spi bus number of the spi-master attached to the mikrobus socket.
+ $ref: /schemas/types.yaml#/definitions/phandle
+
+ uart:
+ description: uart port attached to the mikrobus socket
+ $ref: /schemas/types.yaml#/definitions/phandle
+
+ pwms:
+ description: the pwm-controller corresponding to the mikroBUS PWM pin.
+ maxItems: 1
+
+ spi-cs:
+ description: spi chip-select numbers corresponding to the chip-selects on the mikrobus socket.
+ $ref: /schemas/types.yaml#/definitions/uint32-array
+ items:
+ - description: chip select corresponding to CS pin
+ - description: chip select corresponding to RST pin
+
+required:
+ - compatible
+ - pinctrl-0
+ - pinctrl-1
+ - pinctrl-2
+ - pinctrl-3
+ - pinctrl-4
+ - pinctrl-5
+ - pinctrl-6
+ - pinctrl-7
+ - pinctrl-8
+ - i2c-adapter
+ - spi-controller
+ - spi-cs
+ - uart
+ - pwms
+ - mikrobus-gpios
+
+additionalProperties: false
+
+examples:
+ - |
+ #include <dt-bindings/gpio/gpio.h>
+
+ mikrobus {
+ compatible = "mikrobus-connector";
+ pinctrl-names = "default", "pwm_default", "pwm_gpio","uart_default", "uart_gpio", "i2c_default",
+ "i2c_gpio", "spi_default", "spi_gpio";
+ pinctrl-0 = <&P2_03_gpio_input_pin &P1_04_gpio_pin &P1_02_gpio_pin>;
+ pinctrl-1 = <&P2_01_pwm_pin>;
+ pinctrl-2 = <&P2_01_gpio_pin>;
+ pinctrl-3 = <&P2_05_uart_pin &P2_07_uart_pin>;
+ pinctrl-4 = <&P2_05_gpio_pin &P2_07_gpio_pin>;
+ pinctrl-5 = <&P2_09_i2c_pin &P2_11_i2c_pin>;
+ pinctrl-6 = <&P2_09_gpio_pin &P2_11_gpio_pin>;
+ pinctrl-7 = <&P1_12_spi_pin &P1_10_spi_pin &P1_08_spi_sclk_pin &P1_06_spi_cs_pin>;
+ pinctrl-8 = <&P1_12_gpio_pin &P1_10_gpio_pin &P1_08_gpio_pin &P1_06_gpio_pin>;
+ pwms = <&ehrpwm1 0 500000 0>;
+ i2c-adapter = <&i2c1>;
+ spi-controller = <&spi1>;
+ spi-cs = <0 1>;
+ uart = <&uart1>;
+ mikrobus-gpios = <&gpio1 18 GPIO_ACTIVE_HIGH>, <&gpio0 23 GPIO_ACTIVE_HIGH>,
+ <&gpio0 30 GPIO_ACTIVE_HIGH>, <&gpio0 31 GPIO_ACTIVE_HIGH>,
+ <&gpio0 15 GPIO_ACTIVE_HIGH>, <&gpio0 14 GPIO_ACTIVE_HIGH>,
+ <&gpio0 4 GPIO_ACTIVE_HIGH>, <&gpio0 3 GPIO_ACTIVE_HIGH>,
+ <&gpio0 2 GPIO_ACTIVE_HIGH>, <&gpio0 5 GPIO_ACTIVE_HIGH>,
+ <&gpio2 25 GPIO_ACTIVE_HIGH>, <&gpio2 3 GPIO_ACTIVE_HIGH>;
+ };
diff --git a/MAINTAINERS b/MAINTAINERS
index 375d34363777..69418a058c6b 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -14767,6 +14767,12 @@ M: Oliver Neukum <oliver@xxxxxxxxxx>
S: Maintained
F: drivers/usb/image/microtek.*
+MIKROBUS
+M: Ayush Singh <ayushdevel1325@xxxxxxxxx>
+M: Vaishnav M A <vaishnav@xxxxxxxxxxxxxxx>
+S: Maintained
+F: Documentation/devicetree/bindings/misc/mikrobus-connector.yaml
+
MIKROTIK CRS3XX 98DX3236 BOARD SUPPORT
M: Luka Kovacic <luka.kovacic@xxxxxxxxxx>
M: Luka Perkov <luka.perkov@xxxxxxxxxx>
After going through all the discussions here, I have a few questions:
1. Is the old `*_register_device(controller, board_info)` style
discouraged in favor of using device tree, at least for drivers using
multiple fundamental buses (i2c, spi, etc)? Or is the problem just that
these bindings do not leave open the possibility of using device tree
overlays? Will it be fine if the dt bindings allow for dt overlays, but
the driver still uses imperative registering of board?
2. Is the preferred way to handle virtual devices (like those created by
greybus subsystem) now device tree? Is that one of the blockers for
greybus i2c, spi etc to still be in staging?
3. How are virtual devices created in device tree? If I register an i2c
adapter using `i2c_add_adapter`, is the device tree entry is dynamically
created, which can then be used by a device tree overlay?
Ayush Singh