HelenOS sources
write32 143 boot/arch/arm32/src/putchar.c write32(BCM2835_UART0_CR, 0x0); /* Disable UART */
write32 144 boot/arch/arm32/src/putchar.c write32(BCM2835_UART0_ICR, 0x7f); /* Clear interrupts */
write32 145 boot/arch/arm32/src/putchar.c write32(BCM2835_UART0_IBRD, 1); /* Set integer baud rate */
write32 146 boot/arch/arm32/src/putchar.c write32(BCM2835_UART0_FBRD, 40); /* Set fractional baud rate */
write32 147 boot/arch/arm32/src/putchar.c write32(BCM2835_UART0_LCRH,
write32 150 boot/arch/arm32/src/putchar.c write32(BCM2835_UART0_CR,
write32 166 boot/arch/arm32/src/putchar.c write32(BCM2835_UART0_DR, byte);
HelenOS homepage, sources at GitHub