Support for NXP's imx SoC debug uart

Add NXP's imx SoC debug uart driver.
Signed-off-by: Anson Huang <Anson.Huang@nxp.com>

plat/imx/common/include/imx8_lpuart.h

+/*
+ * Copyright (c) 2015-2018, ARM Limited and Contributors. All rights reserved.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#ifndef __IMX_LPUART_H__
+#define __IMX_LPUART_H__
+
+#include <console.h>
+
+#define VERID	0x0
+#define PARAM	0x4
+#define GLOBAL	0x8
+#define PINCFG	0xC
+#define BAUD	0x10
+#define STAT	0x14
+#define CTRL	0x18
+#define DATA	0x1C
+#define MATCH	0x20
+#define MODIR	0x24
+#define FIFO	0x28
+#define WATER	0x2c
+
+#define US1_TDRE	(1 << 23)
+#define US1_RDRF	(1 << 21)
+
+#define CTRL_TE		(1 << 19)
+#define CTRL_RE		(1 << 18)
+
+#define FIFO_TXFE	0x80
+#define FIFO_RXFE	0x40
+
+#define WATER_TXWATER_OFF	1
+#define WATER_RXWATER_OFF	16
+
+#define LPUART_CTRL_PT_MASK	0x1
+#define LPUART_CTRL_PE_MASK	0x2
+#define LPUART_CTRL_M_MASK	0x10
+
+#define LPUART_BAUD_OSR_MASK                     (0x1F000000U)
+#define LPUART_BAUD_OSR_SHIFT                    (24U)
+#define LPUART_BAUD_OSR(x)                       (((uint32_t)(((uint32_t)(x)) << LPUART_BAUD_OSR_SHIFT)) & LPUART_BAUD_OSR_MASK)
+
+#define LPUART_BAUD_SBR_MASK                     (0x1FFFU)
+#define LPUART_BAUD_SBR_SHIFT                    (0U)
+#define LPUART_BAUD_SBR(x)                       (((uint32_t)(((uint32_t)(x)) << LPUART_BAUD_SBR_SHIFT)) & LPUART_BAUD_SBR_MASK)
+
+#define LPUART_BAUD_SBNS_MASK                    (0x2000U)
+#define LPUART_BAUD_BOTHEDGE_MASK                (0x20000U)
+#define LPUART_BAUD_M10_MASK                     (0x20000000U)
+
+#ifndef __ASSEMBLY__
+
+#include <types.h>
+
+typedef struct {
+	console_t console;
+	uintptr_t base;
+} console_lpuart_t;
+
+int console_lpuart_register(uintptr_t baseaddr, uint32_t clock, uint32_t baud,
+			   console_lpuart_t *console);
+#endif /*__ASSEMBLY__*/
+
+#endif  /* __IMX_LPUART_H__*/

plat/imx/common/lpuart_console.S

+/*
+ * Copyright (c) 2015-2018, ARM Limited and Contributors. All rights reserved.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#include <arch.h>
+#include <asm_macros.S>
+#include <console_macros.S>
+#include <assert_macros.S>
+#include "imx8_lpuart.h"
+
+	.globl	console_lpuart_register
+	.globl	console_lpuart_init
+	.globl	console_lpuart_putc
+	.globl	console_lpuart_getc
+
+func console_lpuart_register
+	mov	x7, x30
+	mov	x6, x3
+	cbz	x6, register_fail
+	str	x0, [x6, #CONSOLE_T_DRVDATA]
+
+	bl	console_lpuart_init
+	cbz	x0, register_fail
+
+	mov	x0, x6
+	mov	x30, x7
+	finish_console_register lpuart
+
+register_fail:
+	ret	x7
+endfunc console_lpuart_register
+
+func console_lpuart_init
+	mov	w0, #1
+	ret
+endfunc console_lpuart_init
+
+func console_lpuart_putc
+	ldr	x1, [x1, #CONSOLE_T_DRVDATA]
+	cbz	x1, putc_error
+	/* Prepare '\r' to '\n' */
+	cmp	w0, #0xA
+	b.ne	2f
+1:
+	/* Check if the transmit FIFO is full */
+	ldr	w2, [x1, #STAT]
+	tbz	w2, #23, 1b
+	mov	w2, #0xD
+	str	w2, [x1, #DATA]
+2:
+	/* Check if the transmit FIFO is full */
+	ldr	w2, [x1, #STAT]
+	tbz	w2, #23, 2b
+	str	w0, [x1, #DATA]
+	ret
+putc_error:
+	mov	w0, #-1
+	ret
+endfunc console_lpuart_putc
+
+func console_lpuart_getc
+	ldr	x0, [x0, #CONSOLE_T_DRVDATA]
+	cbz	x0, getc_error
+	/* Check if the receive FIFO state */
+	ret
+getc_error:
+	mov	w0, #-1
+	ret
+endfunc console_lpuart_getc