i2c: Add compiletime check macro for validating the i2c pins.

Use 0x7 as error value for an invalid I2C SDA/SCL-pin value.
The macro `I2CBUS_VALID` checks for this value.
When a invalid pin is ues, the compiler errors out with:
  "machine.c:<line>: error 176: sizeof applied to an incomplete type",

Error message is not ideal but at-least points to the right location in
the code.
This commit is contained in:
René van Dorst committed 2026-09-20 11:25:35 +02:00
1 parent b5fe9f217f
commit 19ccc4003d
2 files changed
+15 -9

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+1 -1
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@@ -398,7 +398,7 @@ void setup_i2c(void) __banked
reg_read_m(RTL837X_PIN_MUX_1);
for (uint8_t sfp = 0; sfp < machine.n_sfp; sfp++) {
uint8_t i2c = machine.sfp_port[sfp].i2c;
uint8_t scl_bus = (i2c >> RTL837X_REG_I2C_SCL_SHIFT) & 0x03;
uint8_t scl_bus = (i2c >> RTL837X_REG_I2C_SCL_SHIFT) & 0x07;
uint8_t sda_bus = (i2c >> RTL837X_REG_I2C_SDA_SHIFT) & 0x07;
print_string("Configuring I2C for SFP idx="); print_byte(sfp); print_string(" SCL="); print_byte(scl_bus); print_string(", SDA="); print_byte(sda_bus); write_char('\n');
switch (scl_bus) {
+14 -8
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@@ -5,22 +5,28 @@
#include "rtl837x_regs.h"
#include "rtl837x_common.h"
#define I2CBUS_INVALID (7)
// This is a MACRO to check if I2C_BUS_FROM_SDA_PIN or I2C_BUS_FROM_SCL_PIN don't return I2CBUS_INVALID.
// When I2CBUS_INVALID is returned, compiler stops with "machine.c:<line>: error 176: sizeof applied to an incomplete type"
#define I2CBUS_VALID(bus) (0 * sizeof(char[(bus) != I2CBUS_INVALID ? 1 : 0]))
#define I2CBUS(sda, scl) \
((uint8_t)((I2C_BUS_FROM_SCL_PIN(scl) << RTL837X_REG_I2C_SCL_SHIFT) | \
(I2C_BUS_FROM_SDA_PIN(sda) << RTL837X_REG_I2C_SDA_SHIFT)))
((uint8_t)((I2C_BUS_FROM_SCL_PIN(scl) << RTL837X_REG_I2C_SCL_SHIFT) | \
(I2C_BUS_FROM_SDA_PIN(sda) << RTL837X_REG_I2C_SDA_SHIFT) | \
I2CBUS_VALID(I2C_BUS_FROM_SCL_PIN(scl)) | \
I2CBUS_VALID(I2C_BUS_FROM_SDA_PIN(sda))))
#define I2C_BUS_FROM_SDA_PIN(sda_pin) \
((sda_pin) == GPIO47_I2C_SDA0 ? (uint8_t)0 : \
(sda_pin) == GPIO49_I2C_SDA1 ? (uint8_t)1 : \
(sda_pin) == GPIO51_I2C_SDA2_UART1_RX ? (uint8_t)2 : \
(sda_pin) == GPIO41_I2C_SDA3_MDIO1 ? (uint8_t)3 : \
(sda_pin) == GPIO39_I2C_SDA4 ? (uint8_t)4 : -1)
((sda_pin) == GPIO47_I2C_SDA0 ? 0 : \
(sda_pin) == GPIO49_I2C_SDA1 ? 1 : \
(sda_pin) == GPIO51_I2C_SDA2_UART1_RX ? 2 : \
(sda_pin) == GPIO41_I2C_SDA3_MDIO1 ? 3 : \
(sda_pin) == GPIO39_I2C_SDA4 ? 4 : I2CBUS_INVALID)
#define I2C_BUS_FROM_SCL_PIN(scl_pin) \
((scl_pin) == GPIO46_I2C_SCL0 ? 0 : \
(scl_pin) == GPIO48_I2C_SCL1 ? 1 : \
(scl_pin) == GPIO50_I2C_SCL2_UART1_TX ? 2 : \
(scl_pin) == GPIO40_I2C_SCL3_MDC1 ? 3 : -1)
(scl_pin) == GPIO40_I2C_SCL3_MDC1 ? 3 : I2CBUS_INVALID)
#if defined(MACHINE_KP_9000_6XHML_X2) || \
defined(MACHINE_KP_9000_6XH_X2_V1_1) || \