From: Vikas Manocha <vikas.manocha@st.com>
Date: Mon, 4 Apr 2016 23:49:02 +0000 (-0700)
Subject: stm32: stm32_flash: add memory barrier during flash write
X-Git-Url: http://git.dujemihanovic.xyz/?a=commitdiff_plain;h=9082517a85930740f59966fcf13293c38792afe8;p=u-boot.git

stm32: stm32_flash: add memory barrier during flash write

After writing data to flash space, next instruction is checking if flash
controller is busy writing to the flash memory. Memory barrier is required here
to avoid transaction re-ordering for data write and busy status check.

Signed-off-by: Vikas Manocha <vikas.manocha@st.com>
---

diff --git a/drivers/mtd/stm32_flash.c b/drivers/mtd/stm32_flash.c
index 71f48543a3..e16b6cd674 100644
--- a/drivers/mtd/stm32_flash.c
+++ b/drivers/mtd/stm32_flash.c
@@ -137,6 +137,10 @@ int write_buff(flash_info_t *info, uchar *src, ulong addr, ulong cnt)
 	/* To make things simple use byte writes only */
 	for (i = 0; i < cnt; i++) {
 		*(uchar *)(addr + i) = src[i];
+		/*  avoid re-ordering flash data write and busy status
+		 *  check as flash memory space attributes are generally Normal
+		 */
+		mb();
 		while (readl(&STM32_FLASH->sr) & STM32_FLASH_SR_BSY)
 			;
 	}