drivers/arm/pl011/aarch32/pl011_console.S

/*
 * Copyright (c) 2016-2017, ARM Limited and Contributors. All rights reserved.
 *
 * SPDX-License-Identifier: BSD-3-Clause
 */
#include <arch.h>
#include <asm_macros.S>
#include <pl011.h>

/*
 * Pull in generic functions to provide backwards compatibility for
 * platform makefiles
 */
#include "../../../console/aarch32/console.S"

	.globl	console_core_init
	.globl	console_core_putc
	.globl	console_core_getc
	.globl	console_core_flush


	/* -----------------------------------------------
	 * int console_core_init(uintptr_t base_addr,
	 * unsigned int uart_clk, unsigned int baud_rate)
	 * Function to initialize the console without a
	 * C Runtime to print debug information. This
	 * function will be accessed by console_init and
	 * crash reporting.
	 * In: r0 - console base address
	 *     r1 - Uart clock in Hz
	 *     r2 - Baud rate
	 * Out: return 1 on success else 0 on error
	 * Clobber list : r1, r2, r3
	 * -----------------------------------------------
	 */
func console_core_init
	/* Check the input base address */
	cmp	r0, #0
	beq	core_init_fail
#if !PL011_GENERIC_UART
	/* Check baud rate and uart clock for sanity */
	cmp	r1, #0
	beq	core_init_fail
	cmp	r2, #0
	beq	core_init_fail
	/* Disable the UART before initialization */
	ldr	r3, [r0, #UARTCR]
	bic	r3, r3, #PL011_UARTCR_UARTEN
	str	r3, [r0, #UARTCR]
	/* Program the baudrate */
	/* Divisor =  (Uart clock * 4) / baudrate */
	lsl	r1, r1, #2
	udiv	r2, r1, r2
	/* IBRD = Divisor >> 6 */
	lsr	r1, r2, #6
	/* Write the IBRD */
	str	r1, [r0, #UARTIBRD]
	/* FBRD = Divisor & 0x3F */
	and	r1, r2, #0x3f
	/* Write the FBRD */
	str	r1, [r0, #UARTFBRD]
	mov	r1, #PL011_LINE_CONTROL
	str	r1, [r0, #UARTLCR_H]
	/* Clear any pending errors */
	mov	r1, #0
	str	r1, [r0, #UARTECR]
	/* Enable tx, rx, and uart overall */
	ldr	r1, =(PL011_UARTCR_RXE | PL011_UARTCR_TXE | PL011_UARTCR_UARTEN)
	str	r1, [r0, #UARTCR]
#endif
	mov	r0, #1
	bx	lr
core_init_fail:
	mov	r0, #0
	bx	lr
endfunc console_core_init

	/* --------------------------------------------------------
	 * int console_core_putc(int c, uintptr_t base_addr)
	 * Function to output a character over the console. It
	 * returns the character printed on success or -1 on error.
	 * In : r0 - character to be printed
	 *      r1 - console base address
	 * Out : return -1 on error else return character.
	 * Clobber list : r2
	 * --------------------------------------------------------
	 */
func console_core_putc
	/* Check the input parameter */
	cmp	r1, #0
	beq	putc_error
	/* Prepend '\r' to '\n' */
	cmp	r0, #0xA
	bne	2f
1:
	/* Check if the transmit FIFO is full */
	ldr	r2, [r1, #UARTFR]
	tst	r2, #PL011_UARTFR_TXFF
	bne	1b
	mov	r2, #0xD
	str	r2, [r1, #UARTDR]
2:
	/* Check if the transmit FIFO is full */
	ldr	r2, [r1, #UARTFR]
	tst	r2, #PL011_UARTFR_TXFF
	bne	2b
	str	r0, [r1, #UARTDR]
	bx	lr
putc_error:
	mov	r0, #-1
	bx	lr
endfunc console_core_putc

	/* ---------------------------------------------
	 * int console_core_getc(uintptr_t base_addr)
	 * Function to get a character from the console.
	 * It returns the character grabbed on success
	 * or -1 on error.
	 * In : r0 - console base address
	 * Clobber list : r0, r1
	 * ---------------------------------------------
	 */
func console_core_getc
	cmp	r0, #0
	beq	getc_error
1:
	/* Check if the receive FIFO is empty */
	ldr	r1, [r0, #UARTFR]
	tst	r1, #PL011_UARTFR_RXFE
	bne	1b
	ldr	r1, [r0, #UARTDR]
	mov	r0, r1
	bx	lr
getc_error:
	mov	r0, #-1
	bx	lr
endfunc console_core_getc

	/* ---------------------------------------------
	 * int console_core_flush(uintptr_t base_addr)
	 * Function to force a write of all buffered
	 * data that hasn't been output.
	 * In : r0 - console base address
	 * Out : return -1 on error else return 0.
	 * Clobber list : r0, r1
	 * ---------------------------------------------
	 */
func console_core_flush
	cmp	r0, #0
	beq	flush_error

1:
	/* Loop while the transmit FIFO is busy */
	ldr	r1, [r0, #UARTFR]
	tst	r1, #PL011_UARTFR_BUSY
	bne	1b

	mov	r0, #0
	bx	lr
flush_error:
	mov	r0, #-1
	bx	lr
endfunc console_core_flush