Implement console_flush() for PL011

This function ensures that console output is flushed, for example
before shutting down or use by another component.

Implemented for both AArch64 and AArch32.

Change-Id: Ie19dbe02826027be819af700b7e4c8b3d2b7829b
Signed-off-by: Antonio Nino Diaz <antonio.ninodiaz@arm.com>

2 files changed, 86 insertions, 2 deletions

diff --git a/drivers/arm/pl011/aarch32/pl011_console.S b/drivers/arm/pl011/aarch32/pl011_console.S
index a9d9f24..5677f04 100644
--- a/drivers/arm/pl011/aarch32/pl011_console.S
+++ b/drivers/arm/pl011/aarch32/pl011_console.S
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2016, ARM Limited and Contributors. All rights reserved.
+ * Copyright (c) 2016-2017, ARM Limited and Contributors. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are met:
@@ -33,8 +33,10 @@
 
 	.globl	console_init
 	.globl	console_putc
+	.globl	console_flush
 	.globl	console_core_init
 	.globl	console_core_putc
+	.globl	console_core_flush
 	.globl	console_getc
 
 	/*
@@ -197,3 +199,44 @@ getc_error:
 	mov	r0, #-1
 	bx	lr
 endfunc console_getc
+
+	/* ---------------------------------------------
+	 * int console_flush(void)
+	 * Function to force a write of all buffered
+	 * data that hasn't been output. It returns 0
+	 * upon successful completion, otherwise it
+	 * returns -1.
+	 * Clobber list : r0, r1
+	 * ---------------------------------------------
+	 */
+func console_flush
+	ldr	r1, =console_base
+	ldr	r0, [r1]
+	b	console_core_flush
+endfunc console_flush
+
+	/* ---------------------------------------------
+	 * 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
diff --git a/drivers/arm/pl011/aarch64/pl011_console.S b/drivers/arm/pl011/aarch64/pl011_console.S
index 352beb9..6487c37 100644
--- a/drivers/arm/pl011/aarch64/pl011_console.S
+++ b/drivers/arm/pl011/aarch64/pl011_console.S
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2013-2016, ARM Limited and Contributors. All rights reserved.
+ * Copyright (c) 2013-2017, ARM Limited and Contributors. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are met:
@@ -33,8 +33,10 @@
 
 	.globl	console_init
 	.globl	console_putc
+	.globl	console_flush
 	.globl	console_core_init
 	.globl	console_core_putc
+	.globl	console_core_flush
 	.globl	console_getc
 
 	/*
@@ -187,3 +189,42 @@ getc_error:
 	mov	w0, #-1
 	ret
 endfunc console_getc
+
+	/* ---------------------------------------------
+	 * int console_flush(void)
+	 * Function to force a write of all buffered
+	 * data that hasn't been output. It returns 0
+	 * upon successful completion, otherwise it
+	 * returns -1.
+	 * Clobber list : x0, x1
+	 * ---------------------------------------------
+	 */
+func console_flush
+	adrp	x1, console_base
+	ldr	x0, [x1, :lo12:console_base]
+	b	console_core_flush
+endfunc console_flush
+
+	/* ---------------------------------------------
+	 * int console_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 console_core_flush
+	cbz	x0, flush_error
+
+1:
+	/* Loop until the transmit FIFO is empty */
+	ldr	w1, [x0, #UARTFR]
+	tbnz	w1, #PL011_UARTFR_BUSY_BIT, 1b
+
+	mov	w0, #0
+	ret
+flush_error:
+	mov	w0, #-1
+	ret
+endfunc console_core_flush