Merge changes from topic "st-uart-baudrate" into integration

* changes:
  refactor(st): configure UART baudrate
  docs(stm32mp1): document some compilation flags
  feat(st-uart): manage oversampling by 8
  fix(st-uart): correctly fill BRR register

docs/plat/stm32mp1.rst

@@ -115,6 +115,24 @@ Available storage medias are:
 - ``STM32MP_SPI_NAND``
 - ``STM32MP_SPI_NOR``
 
+Serial boot devices:
+
+- ``STM32MP_UART_PROGRAMMER``
+- ``STM32MP_USB_PROGRAMMER``
+
+
+Other configuration flags:
+
+- | ``DTB_FILE_NAME``: to precise board device-tree blob to be used.
+  | Default: stm32mp157c-ev1.dtb
+- | ``STM32MP_EARLY_CONSOLE``: to enable early traces before clock driver is setup.
+  | Default: 0 (disabled)
+- | ``STM32MP_UART_BAUDRATE``: to select UART baud rate.
+  | Default: 115200
+- | ``STM32_TF_VERSION``: to manage BL2 monotonic counter.
+  | Default: 0
+
+
 Boot with FIP
 ~~~~~~~~~~~~~
 You need to build BL2, BL32 (SP_min or OP-TEE) and BL33 (U-Boot) before building FIP binary.

drivers/st/uart/aarch32/stm32_console.S

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2018-2021, ARM Limited and Contributors. All rights reserved.
+ * Copyright (c) 2018-2022, ARM Limited and Contributors. All rights reserved.
  *
  * SPDX-License-Identifier: BSD-3-Clause
  */
@@ -67,9 +67,24 @@ func console_stm32_core_init
 	bic	r3, r3, #USART_CR2_STOP
 	str	r3, [r0, #USART_CR2]
 	/* Divisor =  (Uart clock + (baudrate / 2)) / baudrate */
-	lsl	r3, r2, #1
+	lsr	r3, r2, #1
 	add	r3, r1, r3
 	udiv	r3, r3, r2
+	cmp	r3, #16
+	bhi	2f
+	/* Oversampling 8 */
+	/* Divisor =  (2 * Uart clock + (baudrate / 2)) / baudrate */
+	lsr	r3, r2, #1
+	add	r3, r3, r1, lsl #1
+	udiv	r3, r3, r2
+	and	r1, r3, #USART_BRR_DIV_FRACTION
+	lsr	r1, r1, #1
+	bic	r3, r3, #USART_BRR_DIV_FRACTION
+	orr	r3, r3, r1
+	ldr	r1, [r0, #USART_CR1]
+	orr	r1, r1, #USART_CR1_OVER8
+	str	r1, [r0, #USART_CR1]
+2:
 	str	r3, [r0, #USART_BRR]
 	/* Enable UART */
 	ldr	r3, [r0, #USART_CR1]

plat/st/common/stm32mp_common.c

@@ -210,7 +210,7 @@ static void set_console(uintptr_t base, uint32_t clk_rate)
 	unsigned int console_flags;
 
 	if (console_stm32_register(base, clk_rate,
-				   STM32MP_UART_BAUDRATE, &console) == 0) {
+				   (uint32_t)STM32MP_UART_BAUDRATE, &console) == 0) {
 		panic();
 	}
 

plat/st/stm32mp1/platform.mk

@@ -10,6 +10,7 @@ BL2_AT_EL3		:=	1
 USE_COHERENT_MEM	:=	0
 
 STM32MP_EARLY_CONSOLE	?=	0
+STM32MP_UART_BAUDRATE	?=	115200
 
 # Allow TF-A to concatenate BL2 & BL32 binaries in a single file,
 # share DTB file between BL2 and BL32
@@ -172,6 +173,7 @@ $(eval $(call assert_numerics,\
 		PLAT_PARTITION_MAX_ENTRIES \
 		STM32_TF_A_COPIES \
 		STM32_TF_VERSION \
+		STM32MP_UART_BAUDRATE \
 )))
 
 $(eval $(call add_defines,\
@@ -189,6 +191,7 @@ $(eval $(call add_defines,\
 		STM32MP_SDMMC \
 		STM32MP_SPI_NAND \
 		STM32MP_SPI_NOR \
+		STM32MP_UART_BAUDRATE \
 		STM32MP_UART_PROGRAMMER \
 		STM32MP_USB_PROGRAMMER \
 		STM32MP_USE_STM32IMAGE \

plat/st/stm32mp1/stm32mp1_def.h

@@ -202,7 +202,6 @@ enum ddr_type {
 #define USART6_BASE			U(0x44003000)
 #define UART7_BASE			U(0x40018000)
 #define UART8_BASE			U(0x40019000)
-#define STM32MP_UART_BAUDRATE		U(115200)
 
 /* For UART crash console */
 #define STM32MP_DEBUG_USART_BASE	UART4_BASE