Unify i2c_master headers (#24846)

* Unify i2c_master headers

* More documentation improvements

* Reorganise PAL mode defaults

docs/drivers/i2c.md

@@ -16,17 +16,22 @@ You can then call the I2C API by including `i2c_master.h` in your code.
 
 ## I2C Addressing {#note-on-i2c-addresses}
 
-All of the addresses expected by this driver should be pushed to the upper 7 bits of the address byte. Setting
+I2C addresses listed on datasheets and the internet are usually represented as a 7-bit value. The eighth bit (the least significant bit) controls whether the operation is a read or a write.
-the lower bit (indicating read/write) will be done by the respective functions. Almost all I2C addresses listed 
-on datasheets and the internet will be represented as 7 bits occupying the lower 7 bits and will need to be
-shifted to the left (more significant) by one bit. This is easy to do via the bitwise shift operator `<< 1`.
 
-You can either do this on each call to the functions below, or once in your definition of the address. For example, if your device has an address of `0x18`:
+All of the address parameters expected by the driver API should therefore be pushed to the upper 7 bits of the address byte; the driver will take care of setting the read/write bit as appropriate.
+
+This is easy to do via the bitwise left shift operator. For example, if your device has an address of `0x18` you might create a define for convenience:
 
 ```c
 #define MY_I2C_ADDRESS (0x18 << 1)
 ```
 
+Or, you can shift the address ahead of time:
+
+```c
+#define MY_I2C_ADDRESS 0x30
+```
+
 See https://www.robot-electronics.co.uk/i2c-tutorial for more information about I2C addressing and other technical details.
 
 ## AVR Configuration {#avr-configuration}
@@ -40,9 +45,9 @@ The following defines can be used to configure the I2C master driver:
 No further setup is required - just connect the `SDA` and `SCL` pins of your I2C devices to the matching pins on the MCU:
 
 |MCU          |`SCL`|`SDA`|
-|------------------|-----|-----|
+|-------------|-----|-----|
-|ATmega16/32U4     |`D0` |`D1` |
+|ATmega16/32U4|`D0` |`D1` |
-|AT90USB64/128     |`D0` |`D1` |
+|AT90USB64/128|`D0` |`D1` |
 |ATmega32A    |`C0` |`C1` |
 |ATmega328/P  |`C5` |`C4` |
 
@@ -52,7 +57,7 @@ The ATmega16/32U2 does not possess I2C functionality, and so cannot use this dri
 
 ## ChibiOS/ARM Configuration {#arm-configuration}
 
-You'll need to determine which pins can be used for I2C -- a an example, STM32 parts generally have multiple I2C peripherals, labeled I2C1, I2C2, I2C3 etc.
+You'll need to determine which pins can be used for I2C -- as an example, STM32 parts generally have multiple I2C peripherals, labeled I2C1, I2C2, I2C3 etc.
 
 To enable I2C, modify your board's `halconf.h` to enable I2C, then modify your board's `mcuconf.h` to enable the peripheral you've chosen:
 
@@ -83,15 +88,19 @@ To enable I2C, modify your board's `halconf.h` to enable I2C, then modify your b
 
 Configuration-wise, you'll need to set up the peripheral as per your MCU's datasheet -- the defaults match the pins for a Proton-C, i.e. STM32F303.
 
-|`config.h` Overrride    |Description                                                   |Default|
+|`config.h` Override|Description                                                  |Default|
-|------------------------|--------------------------------------------------------------|-------|
+|-------------------|-------------------------------------------------------------|-------|
-|`I2C_DRIVER`            |I2C peripheral to use - I2C1 -> `I2CD1`, I2C2 -> `I2CD2` etc. |`I2CD1`|
+|`I2C_DRIVER`       |I2C peripheral to use - I2C1 -> `I2CD1`, I2C2 -> `I2CD2` etc.|`I2CD1`|
-|`I2C1_SCL_PIN`          |The pin definition for SCL                                    |`B6`   |
+|`I2C1_SCL_PIN`     |The pin to use for SCL                                       |`B6`   |
-|`I2C1_SCL_PAL_MODE`     |The alternate function mode for SCL                           |`4`    |
+|`I2C1_SCL_PAL_MODE`|The alternate function mode for SCL                          |`4`    |
-|`I2C1_SDA_PIN`          |The pin definition for SDA                                    |`B7`   |
+|`I2C1_SDA_PIN`     |The pin to use for SDA                                       |`B7`   |
-|`I2C1_SDA_PAL_MODE`     |The alternate function mode for SDA                           |`4`    |
+|`I2C1_SDA_PAL_MODE`|The alternate function mode for SDA                          |`4`    |
 
-The following configuration values depend on the specific MCU in use.
+::: tip
+Currently only a single I2C peripheral is supported, therefore the `I2C1_*` defines are used for configuration regardless of the selected peripheral.
+:::
+
+The following configuration values are dependent on the ChibiOS I2C LLD, which is dictated by the microcontroller.
 
 ### I2Cv1 {#arm-configuration-i2cv1}
 
@@ -168,6 +177,29 @@ Send multiple bytes to the selected I2C device.
 
 ---
 
+### `i2c_status_t i2c_transmit_P(uint8_t address, const uint8_t* data, uint16_t length, uint16_t timeout)` {#api-i2c-transmit-p}
+
+Send multiple bytes from PROGMEM to the selected I2C device.
+
+On ARM devices, this function is simply an alias for `i2c_transmit(address, data, length, timeout)`.
+
+#### Arguments {#api-i2c-transmit-p-arguments}
+
+ - `uint8_t address`  
+   The 7-bit I2C address of the device.
+ - `const uint8_t* data`  
+   A pointer to the data to transmit.
+ - `uint16_t length`  
+   The number of bytes to write. Take care not to overrun the length of `data`.
+ - `uint16_t timeout`  
+   The time in milliseconds to wait for a response from the target device.
+
+#### Return Value {#api-i2c-transmit-p-return}
+
+`I2C_STATUS_TIMEOUT` if the timeout period elapses, `I2C_STATUS_ERROR` if some other error occurs, otherwise `I2C_STATUS_SUCCESS`.
+
+---
+
 ### `i2c_status_t i2c_receive(uint8_t address, uint8_t* data, uint16_t length, uint16_t timeout)` {#api-i2c-receive}
 
 Receive multiple bytes from the selected I2C device.
@@ -177,7 +209,7 @@ Receive multiple bytes from the selected I2C device.
  - `uint8_t address`  
    The 7-bit I2C address of the device.
  - `uint8_t* data`  
-   A pointer to the buffer to read into.
+   A pointer to a buffer to read into.
  - `uint16_t length`  
    The number of bytes to read. Take care not to overrun the length of `data`.
  - `uint16_t timeout`  
@@ -191,7 +223,7 @@ Receive multiple bytes from the selected I2C device.
 
 ### `i2c_status_t i2c_write_register(uint8_t devaddr, uint8_t regaddr, const uint8_t* data, uint16_t length, uint16_t timeout)` {#api-i2c-write-register}
 
-Writes to a register with an 8-bit address on the I2C device.
+Write to a register with an 8-bit address on the I2C device.
 
 #### Arguments {#api-i2c-write-register-arguments}
 
@@ -214,7 +246,7 @@ Writes to a register with an 8-bit address on the I2C device.
 
 ### `i2c_status_t i2c_write_register16(uint8_t devaddr, uint16_t regaddr, const uint8_t* data, uint16_t length, uint16_t timeout)` {#api-i2c-write-register16}
 
-Writes to a register with a 16-bit address (big endian) on the I2C device.
+Write to a register with a 16-bit address (big endian) on the I2C device.
 
 #### Arguments {#api-i2c-write-register16-arguments}
 
@@ -237,7 +269,7 @@ Writes to a register with a 16-bit address (big endian) on the I2C device.
 
 ### `i2c_status_t i2c_read_register(uint8_t devaddr, uint8_t regaddr, uint8_t* data, uint16_t length, uint16_t timeout)` {#api-i2c-read-register}
 
-Reads from a register with an 8-bit address on the I2C device.
+Read from a register with an 8-bit address on the I2C device.
 
 #### Arguments {#api-i2c-read-register-arguments}
 
@@ -260,7 +292,7 @@ Reads from a register with an 8-bit address on the I2C device.
 
 ### `i2c_status_t i2c_read_register16(uint8_t devaddr, uint16_t regaddr, uint8_t* data, uint16_t length, uint16_t timeout)` {#api-i2c-read-register16}
 
-Reads from a register with a 16-bit address (big endian) on the I2C device.
+Read from a register with a 16-bit address (big endian) on the I2C device.
 
 #### Arguments {#api-i2c-read-register16-arguments}
 
@@ -283,16 +315,16 @@ Reads from a register with a 16-bit address (big endian) on the I2C device.
 
 ### `i2c_status_t i2c_ping_address(uint8_t address, uint16_t timeout)` {#api-i2c-ping-address}
 
-Pings the I2C bus for a specific address.
+Ping the I2C bus for a specific address.
 
-On ChibiOS a "best effort" attempt is made by reading a single byte from register 0 at the requested address. This should generally work except for I2C devices that do not not respond to a register 0 read request, which will result in a false negative result (unsuccessful response to ping attempt).
+On ChibiOS a "best effort" attempt is made by reading a single byte from register 0 at the given address. This should generally work except for I2C devices that do not not respond to a register 0 read request, which will result in a false negative result (unsuccessful response to ping attempt).
 
 This function is weakly defined, meaning it can be overridden if necessary for your particular use case.
 
 #### Arguments {#api-i2c-ping-address-arguments}
 
  - `uint8_t address`  
-   The 7-bit I2C address of the device (ie. without the read/write bit - this will be set automatically).
+   The 7-bit I2C address of the device.
  - `uint16_t timeout`  
    The time in milliseconds to wait for a response from the target device.
 

drivers/i2c_master.h

@@ -0,0 +1,141 @@
+// Copyright 2025 QMK
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+#pragma once
+
+#include <stdint.h>
+
+/**
+ * \file
+ *
+ * \defgroup i2c_master I2C Master API
+ *
+ * \brief API to communicate with I2C devices.
+ * \{
+ */
+
+typedef int16_t i2c_status_t;
+
+#define I2C_STATUS_SUCCESS (0)
+#define I2C_STATUS_ERROR (-1)
+#define I2C_STATUS_TIMEOUT (-2)
+
+#define I2C_TIMEOUT_IMMEDIATE (0)
+#define I2C_TIMEOUT_INFINITE (0xFFFF)
+
+/**
+ * \brief Initialize the I2C driver. This function must be called only once, before any of the below functions can be called.
+ *
+ * This function is weakly defined, meaning it can be overridden if necessary for your particular use case.
+ */
+void i2c_init(void);
+
+/**
+ * \brief Send multiple bytes to the selected I2C device.
+ *
+ * \param address The 7-bit I2C address of the device.
+ * \param data A pointer to the data to transmit.
+ * \param length The number of bytes to write. Take care not to overrun the length of `data`.
+ * \param timeout The time in milliseconds to wait for a response from the target device.
+ *
+ * \return `I2C_STATUS_TIMEOUT` if the timeout period elapses, `I2C_STATUS_ERROR` if some other error occurs, otherwise `I2C_STATUS_SUCCESS`.
+ */
+i2c_status_t i2c_transmit(uint8_t address, const uint8_t* data, uint16_t length, uint16_t timeout);
+
+#if defined(__AVR__) || defined(__DOXYGEN__)
+/**
+ * \brief Send multiple bytes from PROGMEM to the selected I2C device.
+ *
+ * On ARM devices, this function is simply an alias for i2c_transmit(address, data, length, timeout).
+ *
+ * \param address The 7-bit I2C address of the device.
+ * \param data A pointer to the data to transmit.
+ * \param length The number of bytes to write. Take care not to overrun the length of `data`.
+ * \param timeout The time in milliseconds to wait for a response from the target device.
+ *
+ * \return `I2C_STATUS_TIMEOUT` if the timeout period elapses, `I2C_STATUS_ERROR` if some other error occurs, otherwise `I2C_STATUS_SUCCESS`.
+ */
+i2c_status_t i2c_transmit_P(uint8_t address, const uint8_t* data, uint16_t length, uint16_t timeout);
+#else
+#    define i2c_transmit_P(address, data, length, timeout) i2c_transmit(address, data, length, timeout)
+#endif
+
+/**
+ * \brief Receive multiple bytes from the selected I2C device.
+ *
+ * \param address The 7-bit I2C address of the device.
+ * \param data A pointer to a buffer to read into.
+ * \param length The number of bytes to read. Take care not to overrun the length of `data`.
+ * \param timeout The time in milliseconds to wait for a response from the target device.
+ *
+ * \return `I2C_STATUS_TIMEOUT` if the timeout period elapses, `I2C_STATUS_ERROR` if some other error occurs, otherwise `I2C_STATUS_SUCCESS`.
+ */
+i2c_status_t i2c_receive(uint8_t address, uint8_t* data, uint16_t length, uint16_t timeout);
+
+/**
+ * \brief Write to a register with an 8-bit address on the I2C device.
+ *
+ * \param devaddr The 7-bit I2C address of the device.
+ * \param regaddr The register address to write to.
+ * \param data A pointer to the data to transmit.
+ * \param length The number of bytes to write. Take care not to overrun the length of `data`.
+ * \param timeout The time in milliseconds to wait for a response from the target device.
+ *
+ * \return `I2C_STATUS_TIMEOUT` if the timeout period elapses, `I2C_STATUS_ERROR` if some other error occurs, otherwise `I2C_STATUS_SUCCESS`.
+ */
+i2c_status_t i2c_write_register(uint8_t devaddr, uint8_t regaddr, const uint8_t* data, uint16_t length, uint16_t timeout);
+
+/**
+ * \brief Write to a register with a 16-bit address (big endian) on the I2C device.
+ *
+ * \param devaddr The 7-bit I2C address of the device.
+ * \param regaddr The register address to write to.
+ * \param data A pointer to the data to transmit.
+ * \param length The number of bytes to write. Take care not to overrun the length of `data`.
+ * \param timeout The time in milliseconds to wait for a response from the target device.
+ *
+ * \return `I2C_STATUS_TIMEOUT` if the timeout period elapses, `I2C_STATUS_ERROR` if some other error occurs, otherwise `I2C_STATUS_SUCCESS`.
+ */
+i2c_status_t i2c_write_register16(uint8_t devaddr, uint16_t regaddr, const uint8_t* data, uint16_t length, uint16_t timeout);
+
+/**
+ * \brief Read from a register with an 8-bit address on the I2C device.
+ *
+ * \param devaddr The 7-bit I2C address of the device.
+ * \param regaddr The register address to read from.
+ * \param data A pointer to a buffer to read into.
+ * \param length The number of bytes to read. Take care not to overrun the length of `data`.
+ * \param timeout The time in milliseconds to wait for a response from the target device.
+ *
+ * \return `I2C_STATUS_TIMEOUT` if the timeout period elapses, `I2C_STATUS_ERROR` if some other error occurs, otherwise `I2C_STATUS_SUCCESS`.
+ */
+i2c_status_t i2c_read_register(uint8_t devaddr, uint8_t regaddr, uint8_t* data, uint16_t length, uint16_t timeout);
+
+/**
+ * \brief Read from a register with a 16-bit address (big endian) on the I2C device.
+ *
+ * \param devaddr The 7-bit I2C address of the device.
+ * \param regaddr The register address to read from.
+ * \param data A pointer to a buffer to read into.
+ * \param length The number of bytes to read. Take care not to overrun the length of `data`.
+ * \param timeout The time in milliseconds to wait for a response from the target device.
+ *
+ * \return `I2C_STATUS_TIMEOUT` if the timeout period elapses, `I2C_STATUS_ERROR` if some other error occurs, otherwise `I2C_STATUS_SUCCESS`.
+ */
+i2c_status_t i2c_read_register16(uint8_t devaddr, uint16_t regaddr, uint8_t* data, uint16_t length, uint16_t timeout);
+
+/**
+ * \brief Ping the I2C bus for a specific address.
+ *
+ * On ChibiOS a "best effort" attempt is made by reading a single byte from register 0 at the given address. This should generally work except for I2C devices that do not not respond to a register 0 read request, which will result in a false negative result (unsuccessful response to ping attempt).
+ *
+ * This function is weakly defined, meaning it can be overridden if necessary for your particular use case.
+ *
+ * \param address The 7-bit I2C address of the device.
+ * \param timeout The time in milliseconds to wait for a response from the target device.
+ *
+ * \return `I2C_STATUS_TIMEOUT` if the timeout period elapses, `I2C_STATUS_ERROR` if some other error occurs, otherwise `I2C_STATUS_SUCCESS`.
+ */
+i2c_status_t i2c_ping_address(uint8_t address, uint16_t timeout);
+
+/** \} */

platforms/avr/drivers/i2c_master.h

@@ -1,41 +0,0 @@
-/*  Copyright (C) 2019 Elia Ritterbusch
- +
- *  This program is free software: you can redistribute it and/or modify
- *  it under the terms of the GNU General Public License as published by
- *  the Free Software Foundation, either version 3 of the License, or
- *  (at your option) any later version.
- *
- *  This program is distributed in the hope that it will be useful,
- *  but WITHOUT ANY WARRANTY; without even the implied warranty of
- *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- *  GNU General Public License for more details.
- *
- *  You should have received a copy of the GNU General Public License
- *  along with this program.  If not, see <https://www.gnu.org/licenses/>.
- */
-/* Library made by: g4lvanix
- * GitHub repository: https://github.com/g4lvanix/I2C-master-lib
- */
-
-#pragma once
-
-#include <stdint.h>
-
-typedef int16_t i2c_status_t;
-
-#define I2C_STATUS_SUCCESS (0)
-#define I2C_STATUS_ERROR (-1)
-#define I2C_STATUS_TIMEOUT (-2)
-
-#define I2C_TIMEOUT_IMMEDIATE (0)
-#define I2C_TIMEOUT_INFINITE (0xFFFF)
-
-void         i2c_init(void);
-i2c_status_t i2c_transmit(uint8_t address, const uint8_t* data, uint16_t length, uint16_t timeout);
-i2c_status_t i2c_transmit_P(uint8_t address, const uint8_t* data, uint16_t length, uint16_t timeout);
-i2c_status_t i2c_receive(uint8_t address, uint8_t* data, uint16_t length, uint16_t timeout);
-i2c_status_t i2c_write_register(uint8_t devaddr, uint8_t regaddr, const uint8_t* data, uint16_t length, uint16_t timeout);
-i2c_status_t i2c_write_register16(uint8_t devaddr, uint16_t regaddr, const uint8_t* data, uint16_t length, uint16_t timeout);
-i2c_status_t i2c_read_register(uint8_t devaddr, uint8_t regaddr, uint8_t* data, uint16_t length, uint16_t timeout);
-i2c_status_t i2c_read_register16(uint8_t devaddr, uint16_t regaddr, uint8_t* data, uint16_t length, uint16_t timeout);
-i2c_status_t i2c_ping_address(uint8_t address, uint16_t timeout);

platforms/chibios/drivers/i2c_master.c

@@ -29,17 +29,37 @@
 #include "i2c_master.h"
 #include "gpio.h"
 #include "chibios_config.h"
-#include <string.h>
 #include <ch.h>
 #include <hal.h>
 
+#ifndef I2C_DRIVER
+#    define I2C_DRIVER I2CD1
+#endif
+
 #ifndef I2C1_SCL_PIN
 #    define I2C1_SCL_PIN B6
 #endif
+
+#ifndef I2C1_SCL_PAL_MODE
+#    ifdef USE_GPIOV1
+#        define I2C1_SCL_PAL_MODE PAL_MODE_ALTERNATE_OPENDRAIN
+#    else
+#        define I2C1_SCL_PAL_MODE 4
+#    endif
+#endif
+
 #ifndef I2C1_SDA_PIN
 #    define I2C1_SDA_PIN B7
 #endif
 
+#ifndef I2C1_SDA_PAL_MODE
+#    ifdef USE_GPIOV1
+#        define I2C1_SDA_PAL_MODE PAL_MODE_ALTERNATE_OPENDRAIN
+#    else
+#        define I2C1_SDA_PAL_MODE 4
+#    endif
+#endif
+
 #ifdef USE_I2CV1
 #    ifndef I2C1_OPMODE
 #        define I2C1_OPMODE OPMODE_I2C
@@ -70,27 +90,6 @@
 #    endif
 #endif
 
-#ifndef I2C_DRIVER
-#    define I2C_DRIVER I2CD1
-#endif
-
-#ifdef USE_GPIOV1
-#    ifndef I2C1_SCL_PAL_MODE
-#        define I2C1_SCL_PAL_MODE PAL_MODE_ALTERNATE_OPENDRAIN
-#    endif
-#    ifndef I2C1_SDA_PAL_MODE
-#        define I2C1_SDA_PAL_MODE PAL_MODE_ALTERNATE_OPENDRAIN
-#    endif
-#else
-// The default PAL alternate modes are used to signal that the pins are used for I2C
-#    ifndef I2C1_SCL_PAL_MODE
-#        define I2C1_SCL_PAL_MODE 4
-#    endif
-#    ifndef I2C1_SDA_PAL_MODE
-#        define I2C1_SDA_PAL_MODE 4
-#    endif
-#endif
-
 static const I2CConfig i2cconfig = {
 #if defined(USE_I2CV1_CONTRIB)
     I2C1_CLOCK_SPEED,

platforms/chibios/drivers/i2c_master.h

@@ -1,42 +0,0 @@
-/* Copyright 2018 Jack Humbert
- * Copyright 2018 Yiancar
- *
- * This program is free software: you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation, either version 2 of the License, or
- * (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program.  If not, see <http://www.gnu.org/licenses/>.
- */
-
-/* This library follows the convention of the AVR i2c_master library.
- * As a result addresses are expected to be already shifted (addr << 1).
- * I2CD1 is the default driver which corresponds to pins B6 and B7. This
- * can be changed.
- * Please ensure that HAL_USE_I2C is TRUE in the halconf.h file and that
- * STM32_I2C_USE_I2C1 is TRUE in the mcuconf.h file.
- */
-#pragma once
-
-#include <stdint.h>
-
-typedef int16_t i2c_status_t;
-
-#define I2C_STATUS_SUCCESS (0)
-#define I2C_STATUS_ERROR (-1)
-#define I2C_STATUS_TIMEOUT (-2)
-
-void         i2c_init(void);
-i2c_status_t i2c_transmit(uint8_t address, const uint8_t* data, uint16_t length, uint16_t timeout);
-i2c_status_t i2c_receive(uint8_t address, uint8_t* data, uint16_t length, uint16_t timeout);
-i2c_status_t i2c_write_register(uint8_t devaddr, uint8_t regaddr, const uint8_t* data, uint16_t length, uint16_t timeout);
-i2c_status_t i2c_write_register16(uint8_t devaddr, uint16_t regaddr, const uint8_t* data, uint16_t length, uint16_t timeout);
-i2c_status_t i2c_read_register(uint8_t devaddr, uint8_t regaddr, uint8_t* data, uint16_t length, uint16_t timeout);
-i2c_status_t i2c_read_register16(uint8_t devaddr, uint16_t regaddr, uint8_t* data, uint16_t length, uint16_t timeout);
-i2c_status_t i2c_ping_address(uint8_t address, uint16_t timeout);