drivers/nxp/console/16550_console.S - filogic/atf - Gitiles

 /*
  * Copyright (c) 2021, ARM Limited and Contributors. All rights reserved.
  *
  * SPDX-License-Identifier: BSD-3-Clause
  */

 #include <arch.h>
 #include <asm_macros.S>
 #include <assert_macros.S>
 #include <console_macros.S>

 /* UART16550 Registers */
 #define UARTTX			0x0
 #define UARTRX			0x0
 #define UARTDLL			0x0
 #define UARTIER			0x1
 #define UARTDLLM		0x1
 #define UARTFCR			0x2
 #define UARTLCR			0x3
 #define UARTLSR			0x5
 #define UARTMCR                 0x4

 /* FIFO Control Register bits */
 #define UARTFCR_FIFOMD_16450	(0 << 6)
 #define UARTFCR_FIFOMD_16550	(1 << 6)
 #define UARTFCR_RXTRIG_1	(0 << 6)
 #define UARTFCR_RXTRIG_4	(1 << 6)
 #define UARTFCR_RXTRIG_8	(2 << 6)
 #define UARTFCR_RXTRIG_16	(3 << 6)
 #define UARTFCR_TXTRIG_1	(0 << 4)
 #define UARTFCR_TXTRIG_4	(1 << 4)
 #define UARTFCR_TXTRIG_8	(2 << 4)
 #define UARTFCR_TXTRIG_16	(3 << 4)
 #define UARTFCR_DMAEN		(1 << 3)	/* Enable DMA mode */
 #define UARTFCR_TXCLR		(1 << 2)	/* Clear contents of Tx FIFO */
 #define UARTFCR_RXCLR		(1 << 1)	/* Clear contents of Rx FIFO */
 #define UARTFCR_FIFOEN		(1 << 0)	/* Enable the Tx/Rx FIFO */
 #define UARTFCR_64FIFO          (1 << 5)

 /* Line Control Register bits */
 #define UARTLCR_DLAB		(1 << 7)	/* Divisor Latch Access */
 #define UARTLCR_SETB		(1 << 6)	/* Set BREAK Condition */
 #define UARTLCR_SETP		(1 << 5)	/* Set Parity to LCR[4] */
 #define UARTLCR_EVEN		(1 << 4)	/* Even Parity Format */
 #define UARTLCR_PAR		(1 << 3)	/* Parity */
 #define UARTLCR_STOP		(1 << 2)	/* Stop Bit */
 #define UARTLCR_WORDSZ_5	0		/* Word Length of 5 */
 #define UARTLCR_WORDSZ_6	1		/* Word Length of 6 */
 #define UARTLCR_WORDSZ_7	2		/* Word Length of 7 */
 #define UARTLCR_WORDSZ_8	3		/* Word Length of 8 */

 /* Line Status Register bits */
 #define UARTLSR_RXFIFOEMT	(1 << 9)	/* Rx Fifo Empty */
 #define UARTLSR_TXFIFOFULL	(1 << 8)	/* Tx Fifo Full */
 #define UARTLSR_RXFIFOERR	(1 << 7)	/* Rx Fifo Error */
 #define UARTLSR_TEMT		(1 << 6)	/* Tx Shift Register Empty */
 #define UARTLSR_THRE		(1 << 5)	/* Tx Holding Register Empty */
 #define UARTLSR_BRK		(1 << 4)	/* Break Condition Detected */
 #define UARTLSR_FERR		(1 << 3)	/* Framing Error */
 #define UARTLSR_PERR		(1 << 3)	/* Parity Error */
 #define UARTLSR_OVRF		(1 << 2)	/* Rx Overrun Error */
 #define UARTLSR_RDR		(1 << 2)	/* Rx Data Ready */

 #define CONSOLE_T_16550_BASE	CONSOLE_T_BASE

 	/*
 	 * "core" functions are low-level implementations that don't require
 	 * writable memory and are thus safe to call in BL1 crash context.
 	 */
 	.globl nxp_console_16550_core_init
 	.globl nxp_console_16550_core_putc
 	.globl nxp_console_16550_core_getc
 	.globl nxp_console_16550_core_flush

 	.globl console_16550_putc
 	.globl console_16550_getc
 	.globl console_16550_flush

 	/* -----------------------------------------------
 	 * int nxp_console_16550_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: x0 - console base address
 	 *     w1 - Uart clock in Hz
 	 *     w2 - Baud rate
 	 * Out: return 1 on success, 0 on error
 	 * Clobber list : x1, x2, x3
 	 * -----------------------------------------------
 	 */
 func nxp_console_16550_core_init
 	/* Check the input base address */
 	cbz	x0, init_fail
 	/* Check baud rate and uart clock for sanity */
 	cbz	w1, init_fail
 	cbz	w2, init_fail

 	/* Program the baudrate */
 	/* Divisor =  Uart clock / (16 * baudrate) */
 	lsl	w2, w2, #4
 	udiv	w2, w1, w2
 	and	w1, w2, #0xff		/* w1 = DLL */
 	lsr	w2, w2, #8
 	and	w2, w2, #0xff		/* w2 = DLLM */
 	ldrb	w3, [x0, #UARTLCR]
 	orr	w3, w3, #UARTLCR_DLAB
 	strb	w3, [x0, #UARTLCR]	/* enable DLL, DLLM programming */
 	strb	w1, [x0, #UARTDLL]	/* program DLL */
 	strb	w2, [x0, #UARTDLLM]	/* program DLLM */
 	mov	w2, #~UARTLCR_DLAB
 	and	w3, w3, w2
 	strb	w3, [x0, #UARTLCR]	/* disable DLL, DLLM programming */

 	/* 8n1 */
 	mov	w3, #3
 	strb	w3, [x0, #UARTLCR]
 	/* no interrupt */
 	mov	w3, #0
 	strb	w3, [x0, #UARTIER]
 	/* enable fifo, DMA */
 	mov	w3, #(UARTFCR_FIFOEN |UARTFCR_TXCLR | UARTFCR_RXCLR)
 	strb	w3, [x0, #UARTFCR]
 	/* DTR + RTS */
 	mov	w3, #3
 	str	w3, [x0, #UARTMCR]
 	mov	w0, #1
 	ret
 init_fail:
 	mov	w0, #0
 	ret
 endfunc nxp_console_16550_core_init

 	.globl nxp_console_16550_register

 	/* -----------------------------------------------
 	 * int nxp_console_16550_register(uintptr_t baseaddr,
 	 *     uint32_t clock, uint32_t baud,
 	 *     console_t *console);
 	 * Function to initialize and register a new 16550
 	 * console. Storage passed in for the console struct
 	 * *must* be persistent (i.e. not from the stack).
 	 * If w1 (UART clock) is 0, initialisation will be
 	 * skipped, relying on previous code to have done
 	 * this already. w2 is ignored then as well.
 	 * In: x0 - UART register base address
 	 *     w1 - UART clock in Hz
 	 *     w2 - Baud rate (ignored if w1 is 0)
 	 *     x3 - pointer to empty console_t struct
 	 * Out: return 1 on success, 0 on error
 	 * Clobber list : x0, x1, x2, x6, x7, x14
 	 * -----------------------------------------------
 	 */
 func nxp_console_16550_register
 	mov	x7, x30
 	mov	x6, x3
 	cbz	x6, register_fail
 	str	x0, [x6, #CONSOLE_T_16550_BASE]

 	/* A clock rate of zero means to skip the initialisation. */
 	cbz	w1, register_16550

 	bl	nxp_console_16550_core_init
 	cbz	x0, register_fail

 register_16550:
 	mov	x0, x6
 	mov	x30, x7
 	finish_console_register 16550 putc=1, getc=ENABLE_CONSOLE_GETC, flush=1

 register_fail:
 	ret	x7
 endfunc nxp_console_16550_register

 	/* --------------------------------------------------------
 	 * int console_16550_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 : w0 - character to be printed
 	 *      x1 - console base address
 	 * Out : return -1 on error else return character.
 	 * Clobber list : x2
 	 * --------------------------------------------------------
 	 */
 func nxp_console_16550_core_putc
 #if ENABLE_ASSERTIONS
 	cmp	x1, #0
 	ASM_ASSERT(ne)
 #endif /* ENABLE_ASSERTIONS */

 	/* Prepend '\r' to '\n' */
 	cmp	w0, #'\n'
 	b.ne	2f
 	/* Check if the transmit FIFO is full */
 1:	ldrb	w2, [x1, #UARTLSR]
 	and	w2, w2, #UARTLSR_THRE        /* #(UARTLSR_TEMT | UARTLSR_THRE)*/
 	cmp	w2, #(UARTLSR_THRE)
 	b.ne	1b
 	mov	w2, #'\r'
 	strb	w2, [x1, #UARTTX]
 	ldrb	w2, [x1, #UARTFCR]
 	orr	w2, w2, #UARTFCR_TXCLR

 	/* Check if the transmit FIFO is full */
 2:	ldrb	w2, [x1, #UARTLSR]
 	and	w2, w2, #(UARTLSR_THRE)
 	cmp	w2, #(UARTLSR_THRE)
 	b.ne	2b
 	strb	w0, [x1, #UARTTX]
 	ret
 endfunc nxp_console_16550_core_putc

 	/* --------------------------------------------------------
 	 * int console_16550_putc(int c, console_t *console)
 	 * Function to output a character over the console. It
 	 * returns the character printed on success or -1 on error.
 	 * In : w0 - character to be printed
 	 *      x1 - pointer to console_t structure
 	 * Out : return -1 on error else return character.
 	 * Clobber list : x2
 	 * --------------------------------------------------------
 	 */
 func console_16550_putc
 #if ENABLE_ASSERTIONS
 	cmp	x1, #0
 	ASM_ASSERT(ne)
 #endif /* ENABLE_ASSERTIONS */
 	ldr	x1, [x1, #CONSOLE_T_16550_BASE]
 	b	nxp_console_16550_core_putc
 endfunc console_16550_putc

 	/* ---------------------------------------------
 	 * int console_16550_core_getc(uintptr_t base_addr)
 	 * Function to get a character from the console.
 	 * It returns the character grabbed on success
 	 * or -1 on if no character is available.
 	 * In :  x0 - console base address
 	 * Out : w0 - character if available, else -1
 	 * Clobber list : x0, x1
 	 * ---------------------------------------------
 	 */
 func nxp_console_16550_core_getc
 #if ENABLE_ASSERTIONS
 	cmp	x0, #0
 	ASM_ASSERT(ne)
 #endif /* ENABLE_ASSERTIONS */

 	/* Check if the receive FIFO is empty */
 1:	ldrb	w1, [x0, #UARTLSR]
 	tbz	w1, #UARTLSR_RDR, 1b
 	ldrb	w0, [x0, #UARTRX]
 	ret
 no_char:
 	mov	w0, #ERROR_NO_PENDING_CHAR
 	ret
 endfunc nxp_console_16550_core_getc

 	/* ---------------------------------------------
 	 * int console_16550_getc(console_t *console)
 	 * Function to get a character from the console.
 	 * It returns the character grabbed on success
 	 * or -1 on if no character is available.
 	 * In :  x0 - pointer to console_t structure
 	 * Out : w0 - character if available, else -1
 	 * Clobber list : x0, x1
 	 * ---------------------------------------------
 	 */
 func console_16550_getc
 #if ENABLE_ASSERTIONS
 	cmp	x1, #0
 	ASM_ASSERT(ne)
 #endif /* ENABLE_ASSERTIONS */
 	ldr	x0, [x0, #CONSOLE_T_16550_BASE]
 	b	nxp_console_16550_core_getc
 endfunc console_16550_getc

 	/* ---------------------------------------------
 	 * int console_16550_core_flush(uintptr_t base_addr)
 	 * Function to force a write of all buffered
 	 * data that hasn't been output.
 	 * In : x0 - console base address
 	 * Out : return -1 on error else return 0.
 	 * Clobber list : x0, x1
 	 * ---------------------------------------------
 	 */
 func nxp_console_16550_core_flush
 #if ENABLE_ASSERTIONS
 	cmp	x0, #0
 	ASM_ASSERT(ne)
 #endif /* ENABLE_ASSERTIONS */

 	/* Loop until the transmit FIFO is empty */
 1:	ldrb	w1, [x0, #UARTLSR]
 	and	w1, w1, #(UARTLSR_THRE)
 	cmp	w1, #(UARTLSR_THRE)
 	b.ne	1b

 	mov	w0, #0
 	ret
 endfunc nxp_console_16550_core_flush

 	/* ---------------------------------------------
 	 * int console_16550_flush(console_t *console)
 	 * Function to force a write of all buffered
 	 * data that hasn't been output.
 	 * In : x0 - pointer to console_t structure
 	 * Out : return -1 on error else return 0.
 	 * Clobber list : x0, x1
 	 * ---------------------------------------------
 	 */
 func console_16550_flush
 #if ENABLE_ASSERTIONS
 	cmp	x0, #0
 	ASM_ASSERT(ne)
 #endif /* ENABLE_ASSERTIONS */
 	ldr	x0, [x0, #CONSOLE_T_16550_BASE]
 	b	nxp_console_16550_core_flush
 endfunc console_16550_flush
	/*
	* Copyright (c) 2021, ARM Limited and Contributors. All rights reserved.
	*
	* SPDX-License-Identifier: BSD-3-Clause
	*/

	#include <arch.h>
	#include <asm_macros.S>
	#include <assert_macros.S>
	#include <console_macros.S>

	/* UART16550 Registers */
	#define UARTTX 0x0
	#define UARTRX 0x0
	#define UARTDLL 0x0
	#define UARTIER 0x1
	#define UARTDLLM 0x1
	#define UARTFCR 0x2
	#define UARTLCR 0x3
	#define UARTLSR 0x5
	#define UARTMCR 0x4

	/* FIFO Control Register bits */
	#define UARTFCR_FIFOMD_16450 (0 << 6)
	#define UARTFCR_FIFOMD_16550 (1 << 6)
	#define UARTFCR_RXTRIG_1 (0 << 6)
	#define UARTFCR_RXTRIG_4 (1 << 6)
	#define UARTFCR_RXTRIG_8 (2 << 6)
	#define UARTFCR_RXTRIG_16 (3 << 6)
	#define UARTFCR_TXTRIG_1 (0 << 4)
	#define UARTFCR_TXTRIG_4 (1 << 4)
	#define UARTFCR_TXTRIG_8 (2 << 4)
	#define UARTFCR_TXTRIG_16 (3 << 4)
	#define UARTFCR_DMAEN (1 << 3) /* Enable DMA mode */
	#define UARTFCR_TXCLR (1 << 2) /* Clear contents of Tx FIFO */
	#define UARTFCR_RXCLR (1 << 1) /* Clear contents of Rx FIFO */
	#define UARTFCR_FIFOEN (1 << 0) /* Enable the Tx/Rx FIFO */
	#define UARTFCR_64FIFO (1 << 5)

	/* Line Control Register bits */
	#define UARTLCR_DLAB (1 << 7) /* Divisor Latch Access */
	#define UARTLCR_SETB (1 << 6) /* Set BREAK Condition */
	#define UARTLCR_SETP (1 << 5) /* Set Parity to LCR[4] */
	#define UARTLCR_EVEN (1 << 4) /* Even Parity Format */
	#define UARTLCR_PAR (1 << 3) /* Parity */
	#define UARTLCR_STOP (1 << 2) /* Stop Bit */
	#define UARTLCR_WORDSZ_5 0 /* Word Length of 5 */
	#define UARTLCR_WORDSZ_6 1 /* Word Length of 6 */
	#define UARTLCR_WORDSZ_7 2 /* Word Length of 7 */
	#define UARTLCR_WORDSZ_8 3 /* Word Length of 8 */

	/* Line Status Register bits */
	#define UARTLSR_RXFIFOEMT (1 << 9) /* Rx Fifo Empty */
	#define UARTLSR_TXFIFOFULL (1 << 8) /* Tx Fifo Full */
	#define UARTLSR_RXFIFOERR (1 << 7) /* Rx Fifo Error */
	#define UARTLSR_TEMT (1 << 6) /* Tx Shift Register Empty */
	#define UARTLSR_THRE (1 << 5) /* Tx Holding Register Empty */
	#define UARTLSR_BRK (1 << 4) /* Break Condition Detected */
	#define UARTLSR_FERR (1 << 3) /* Framing Error */
	#define UARTLSR_PERR (1 << 3) /* Parity Error */
	#define UARTLSR_OVRF (1 << 2) /* Rx Overrun Error */
	#define UARTLSR_RDR (1 << 2) /* Rx Data Ready */

	#define CONSOLE_T_16550_BASE CONSOLE_T_BASE

	/*
	* "core" functions are low-level implementations that don't require
	* writable memory and are thus safe to call in BL1 crash context.
	*/
	.globl nxp_console_16550_core_init
	.globl nxp_console_16550_core_putc
	.globl nxp_console_16550_core_getc
	.globl nxp_console_16550_core_flush

	.globl console_16550_putc
	.globl console_16550_getc
	.globl console_16550_flush

	/* -----------------------------------------------
	* int nxp_console_16550_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: x0 - console base address
	* w1 - Uart clock in Hz
	* w2 - Baud rate
	* Out: return 1 on success, 0 on error
	* Clobber list : x1, x2, x3
	* -----------------------------------------------
	*/
	func nxp_console_16550_core_init
	/* Check the input base address */
	cbz x0, init_fail
	/* Check baud rate and uart clock for sanity */
	cbz w1, init_fail
	cbz w2, init_fail

	/* Program the baudrate */
	/* Divisor = Uart clock / (16 * baudrate) */
	lsl w2, w2, #4
	udiv w2, w1, w2
	and w1, w2, #0xff /* w1 = DLL */
	lsr w2, w2, #8
	and w2, w2, #0xff /* w2 = DLLM */
	ldrb w3, [x0, #UARTLCR]
	orr w3, w3, #UARTLCR_DLAB
	strb w3, [x0, #UARTLCR] /* enable DLL, DLLM programming */
	strb w1, [x0, #UARTDLL] /* program DLL */
	strb w2, [x0, #UARTDLLM] /* program DLLM */
	mov w2, #~UARTLCR_DLAB
	and w3, w3, w2
	strb w3, [x0, #UARTLCR] /* disable DLL, DLLM programming */

	/* 8n1 */
	mov w3, #3
	strb w3, [x0, #UARTLCR]
	/* no interrupt */
	mov w3, #0
	strb w3, [x0, #UARTIER]
	/* enable fifo, DMA */
	mov w3, #(UARTFCR_FIFOEN \|UARTFCR_TXCLR \| UARTFCR_RXCLR)
	strb w3, [x0, #UARTFCR]
	/* DTR + RTS */
	mov w3, #3
	str w3, [x0, #UARTMCR]
	mov w0, #1
	ret
	init_fail:
	mov w0, #0
	ret
	endfunc nxp_console_16550_core_init

	.globl nxp_console_16550_register

	/* -----------------------------------------------
	* int nxp_console_16550_register(uintptr_t baseaddr,
	* uint32_t clock, uint32_t baud,
	* console_t *console);
	* Function to initialize and register a new 16550
	* console. Storage passed in for the console struct
	* must be persistent (i.e. not from the stack).
	* If w1 (UART clock) is 0, initialisation will be
	* skipped, relying on previous code to have done
	* this already. w2 is ignored then as well.
	* In: x0 - UART register base address
	* w1 - UART clock in Hz
	* w2 - Baud rate (ignored if w1 is 0)
	* x3 - pointer to empty console_t struct
	* Out: return 1 on success, 0 on error
	* Clobber list : x0, x1, x2, x6, x7, x14
	* -----------------------------------------------
	*/
	func nxp_console_16550_register
	mov x7, x30
	mov x6, x3
	cbz x6, register_fail
	str x0, [x6, #CONSOLE_T_16550_BASE]

	/* A clock rate of zero means to skip the initialisation. */
	cbz w1, register_16550

	bl nxp_console_16550_core_init
	cbz x0, register_fail

	register_16550:
	mov x0, x6
	mov x30, x7
	finish_console_register 16550 putc=1, getc=ENABLE_CONSOLE_GETC, flush=1

	register_fail:
	ret x7
	endfunc nxp_console_16550_register

	/* --------------------------------------------------------
	* int console_16550_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 : w0 - character to be printed
	* x1 - console base address
	* Out : return -1 on error else return character.
	* Clobber list : x2
	* --------------------------------------------------------
	*/
	func nxp_console_16550_core_putc
	#if ENABLE_ASSERTIONS
	cmp x1, #0
	ASM_ASSERT(ne)
	#endif /* ENABLE_ASSERTIONS */

	/* Prepend '\r' to '\n' */
	cmp w0, #'\n'
	b.ne 2f
	/* Check if the transmit FIFO is full */
	1: ldrb w2, [x1, #UARTLSR]
	and w2, w2, #UARTLSR_THRE /* #(UARTLSR_TEMT \| UARTLSR_THRE)*/
	cmp w2, #(UARTLSR_THRE)
	b.ne 1b
	mov w2, #'\r'
	strb w2, [x1, #UARTTX]
	ldrb w2, [x1, #UARTFCR]
	orr w2, w2, #UARTFCR_TXCLR

	/* Check if the transmit FIFO is full */
	2: ldrb w2, [x1, #UARTLSR]
	and w2, w2, #(UARTLSR_THRE)
	cmp w2, #(UARTLSR_THRE)
	b.ne 2b
	strb w0, [x1, #UARTTX]
	ret
	endfunc nxp_console_16550_core_putc

	/* --------------------------------------------------------
	* int console_16550_putc(int c, console_t *console)
	* Function to output a character over the console. It
	* returns the character printed on success or -1 on error.
	* In : w0 - character to be printed
	* x1 - pointer to console_t structure
	* Out : return -1 on error else return character.
	* Clobber list : x2
	* --------------------------------------------------------
	*/
	func console_16550_putc
	#if ENABLE_ASSERTIONS
	cmp x1, #0
	ASM_ASSERT(ne)
	#endif /* ENABLE_ASSERTIONS */
	ldr x1, [x1, #CONSOLE_T_16550_BASE]
	b nxp_console_16550_core_putc
	endfunc console_16550_putc

	/* ---------------------------------------------
	* int console_16550_core_getc(uintptr_t base_addr)
	* Function to get a character from the console.
	* It returns the character grabbed on success
	* or -1 on if no character is available.
	* In : x0 - console base address
	* Out : w0 - character if available, else -1
	* Clobber list : x0, x1
	* ---------------------------------------------
	*/
	func nxp_console_16550_core_getc
	#if ENABLE_ASSERTIONS
	cmp x0, #0
	ASM_ASSERT(ne)
	#endif /* ENABLE_ASSERTIONS */

	/* Check if the receive FIFO is empty */
	1: ldrb w1, [x0, #UARTLSR]
	tbz w1, #UARTLSR_RDR, 1b
	ldrb w0, [x0, #UARTRX]
	ret
	no_char:
	mov w0, #ERROR_NO_PENDING_CHAR
	ret
	endfunc nxp_console_16550_core_getc

	/* ---------------------------------------------
	* int console_16550_getc(console_t *console)
	* Function to get a character from the console.
	* It returns the character grabbed on success
	* or -1 on if no character is available.
	* In : x0 - pointer to console_t structure
	* Out : w0 - character if available, else -1
	* Clobber list : x0, x1
	* ---------------------------------------------
	*/
	func console_16550_getc
	#if ENABLE_ASSERTIONS
	cmp x1, #0
	ASM_ASSERT(ne)
	#endif /* ENABLE_ASSERTIONS */
	ldr x0, [x0, #CONSOLE_T_16550_BASE]
	b nxp_console_16550_core_getc
	endfunc console_16550_getc

	/* ---------------------------------------------
	* int console_16550_core_flush(uintptr_t base_addr)
	* Function to force a write of all buffered
	* data that hasn't been output.
	* In : x0 - console base address
	* Out : return -1 on error else return 0.
	* Clobber list : x0, x1
	* ---------------------------------------------
	*/
	func nxp_console_16550_core_flush
	#if ENABLE_ASSERTIONS
	cmp x0, #0
	ASM_ASSERT(ne)
	#endif /* ENABLE_ASSERTIONS */

	/* Loop until the transmit FIFO is empty */
	1: ldrb w1, [x0, #UARTLSR]
	and w1, w1, #(UARTLSR_THRE)
	cmp w1, #(UARTLSR_THRE)
	b.ne 1b

	mov w0, #0
	ret
	endfunc nxp_console_16550_core_flush

	/* ---------------------------------------------
	* int console_16550_flush(console_t *console)
	* Function to force a write of all buffered
	* data that hasn't been output.
	* In : x0 - pointer to console_t structure
	* Out : return -1 on error else return 0.
	* Clobber list : x0, x1
	* ---------------------------------------------
	*/
	func console_16550_flush
	#if ENABLE_ASSERTIONS
	cmp x0, #0
	ASM_ASSERT(ne)
	#endif /* ENABLE_ASSERTIONS */
	ldr x0, [x0, #CONSOLE_T_16550_BASE]
	b nxp_console_16550_core_flush
	endfunc console_16550_flush