From 389ec825385042b3896b1fd9171548ba38cdf0b2 Mon Sep 17 00:00:00 2001
From: Karl Palsson <karlp@tweak.net.au>
Date: Mon, 30 Apr 2018 23:29:07 +0000
Subject: [PATCH] stm32f3: flash: add prefetch helpers

Should be added to f2/f4 as well, but the bit definitions are different.
---
 include/libopencm3/stm32/f3/flash.h |  8 ++++++++
 lib/stm32/f3/flash.c                | 21 +++++++++++++++++++++
 2 files changed, 29 insertions(+)

diff --git a/include/libopencm3/stm32/f3/flash.h b/include/libopencm3/stm32/f3/flash.h
index 58a8c9fd..2a2a9775 100644
--- a/include/libopencm3/stm32/f3/flash.h
+++ b/include/libopencm3/stm32/f3/flash.h
@@ -67,6 +67,14 @@
 #define FLASH_CR_MER			(1 << 2)
 #define FLASH_CR_PER			(1 << 1)
 #define FLASH_CR_PG			(1 << 0)
+
+BEGIN_DECLS
+
+void flash_prefetch_enable(void);
+void flash_prefetch_disable(void);
+
+END_DECLS
+
 /**@}*/
 
 #endif
diff --git a/lib/stm32/f3/flash.c b/lib/stm32/f3/flash.c
index 58687161..cac2ea45 100644
--- a/lib/stm32/f3/flash.c
+++ b/lib/stm32/f3/flash.c
@@ -58,5 +58,26 @@ void flash_clear_status_flags(void)
 	flash_clear_eop_flag();
 	flash_clear_bsy_flag();
 }
+
+/**
+ * Enable the FLASH Prefetch Buffer
+ * This buffer is used for instruction fetches and is enabled by default after
+ * reset.
+ */
+void flash_prefetch_enable(void)
+{
+	FLASH_ACR |= FLASH_ACR_PRFTBE;
+}
+
+/**
+ * Disable the FLASH Prefetch Buffer
+ * This buffer is used for instruction fetches and is enabled by default after
+ * reset.
+ */
+void flash_prefetch_disable(void)
+{
+	FLASH_ACR &= ~FLASH_ACR_PRFTBE;
+}
+
 /**@}*/