android_kernel_oneplus_msm8998/arch/mips/boot/compressed/uart-alchemy.c

#include <asm/mach-au1x00/au1000.h>

void putc(char c)
{
	/* all current (Jan. 2010) in-kernel boards */
	alchemy_uart_putchar(UART0_PHYS_ADDR, c);
}