Merge pull request #501 from jcastillo-arm/jc/tf-issues/300

Disable PL011 UART before configuring it

docs/porting-guide.md

@@ -1860,7 +1860,7 @@ they can be invoked without a C Runtime stack.
     Return   : int
 
 This API is used by the crash reporting mechanism to initialize the crash
-console. It should only use the general purpose registers x0 to x2 to do the
+console. It must only use the general purpose registers x0 to x4 to do the
 initialization and returns 1 on success.
 
 ### Function : plat_crash_console_putc
@@ -1869,7 +1869,7 @@ initialization and returns 1 on success.
     Return   : int
 
 This API is used by the crash reporting mechanism to print a character on the
-designated crash console. It should only use general purpose registers x1 and
+designated crash console. It must only use general purpose registers x1 and
 x2 to do its work. The parameter and the return value are in general purpose
 register x0.
 

drivers/arm/pl011/pl011_console.S

@@ -54,7 +54,7 @@
 	 *     w1 - Uart clock in Hz
 	 *     w2 - Baud rate
 	 * Out: return 1 on success else 0 on error
-	 * Clobber list : x1, x2
+	 * Clobber list : x1, x2, x3, x4
 	 * -----------------------------------------------
 	 */
 func console_core_init
@@ -64,6 +64,20 @@ func console_core_init
 	/* Check baud rate and uart clock for sanity */
 	cbz	w1, core_init_fail
 	cbz	w2, core_init_fail
+	/* Disable uart before programming */
+	ldr	w3, [x0, #UARTCR]
+	mov	w4, #PL011_UARTCR_UARTEN
+	bic	w3, w3, w4
+	str	w3, [x0, #UARTCR]
+	/* Flush the transmit FIFO */
+	ldr	w3, [x0, #UARTLCR_H]
+	mov	w4, #PL011_UARTLCR_H_FEN
+	bic	w3, w3, w4
+	str	w3, [x0, #UARTLCR_H]
+	/* Wait for the end of Tx of current character */
+busy_loop:
+	ldr	w3, [x0, #UARTFR]
+	tbnz	w3, #PL011_UARTFR_BUSY_BIT, busy_loop
 	/* Program the baudrate */
 	/* Divisor =  (Uart clock * 4) / baudrate */
 	lsl	w1, w1, #2

drivers/console/console.S

@@ -54,7 +54,7 @@
 	 *     w1 - Uart clock in Hz
 	 *     w2 - Baud rate
 	 * out: return 1 on success else 0 on error
-	 * Clobber list : x1 - x3
+	 * Clobber list : x1 - x4
 	 * -----------------------------------------------
 	 */
 func console_init

include/drivers/arm/pl011.h

@@ -71,6 +71,7 @@
 
 #define PL011_UARTFR_TXFF_BIT	5	/* Transmit FIFO full bit in UARTFR register */
 #define PL011_UARTFR_RXFE_BIT	4	/* Receive FIFO empty bit in UARTFR register */
+#define PL011_UARTFR_BUSY_BIT	3	/* UART busy bit in UARTFR register */
 
 /* Control reg bits */
 #if !PL011_GENERIC_UART

plat/arm/common/aarch64/arm_helpers.S

@@ -66,7 +66,7 @@ endfunc plat_arm_calc_core_pos
 	 * int plat_crash_console_init(void)
 	 * Function to initialize the crash console
 	 * without a C Runtime to print crash report.
-	 * Clobber list : x0, x1, x2
+	 * Clobber list : x0 - x4
 	 * ---------------------------------------------
 	 */
 func plat_crash_console_init

plat/mediatek/mt8173/aarch64/plat_helpers.S

@@ -63,7 +63,7 @@ endfunc platform_is_primary_cpu
 	 * int plat_crash_console_init(void)
 	 * Function to initialize the crash console
 	 * without a C Runtime to print crash report.
-	 * Clobber list : x0, x1, x2
+	 * Clobber list : x0 - x4
 	 * ---------------------------------------------
 	 */
 func plat_crash_console_init

plat/nvidia/tegra/common/aarch64/tegra_helpers.S

@@ -186,7 +186,7 @@ endfunc platform_mem_init
 	 * int plat_crash_console_init(void)
 	 * Function to initialize the crash console
 	 * without a C Runtime to print crash report.
-	 * Clobber list : x0, x1, x2
+	 * Clobber list : x0 - x4
 	 * ---------------------------------------------
 	 */
 func plat_crash_console_init