Basic flash peripheral management api for board bringup

4 files changed, 52 insertions, 28 deletions

diff --git a/libmaple/flash.c b/libmaple/flash.c
index 9442c44..828f938 100644
--- a/libmaple/flash.c
+++ b/libmaple/flash.c
@@ -22,32 +22,49 @@
  * THE SOFTWARE.
  * ****************************************************************************/
 
+/**
+ *  @brief flash peripheral management functions
+ */
+
+
 #include "libmaple.h"
 #include "flash.h"
 
-#define ACR_PRFTBE                ((uint32)0xFFFFFFEF)
-#define ACR_PRFTBE_ENABLE ((uint32)0x00000010)  /* FLASH Prefetch Buffer Enable */
-#define ACR_PRFTBE_DISABLE ((uint32)0x00000000)  /* FLASH Prefetch Buffer Disable */
+/* flash registers  */
+#define FLASH_BASE                      0x40022000
+#define FLASH_ACR                       FLASH_BASE
+
+/* flash prefetcher  */
+#define ACR_PRFTBE                      BIT(4)
+#define ACR_PRFTBE_ENABLE               BIT(4)
 
-#define ACR_LATENCY               ((uint32)0x00000038)
-#define ACR_LATENCY_0                ((uint32)0x00000000)  /* FLASH Zero Latency cycle */
-#define ACR_LATENCY_1                ((uint32)0x00000001)  /* FLASH One Latency cycle */
-#define ACR_LATENCY_2                ((uint32)0x00000002)  /* FLASH Two Latency cycles */
+/* flash wait states  */
+#define ACR_LATENCY                     (0x7)
 
+#define FLASH_WRITE_ACR(val)            __write(FLASH_ACR, val)
+#define FLASH_READ_ACR()                __read(FLASH_ACR)
+
+/**
+ * @brief turn on the hardware prefetcher
+ */
 void flash_enable_prefetch(void) {
-   uint32 acr = __read(FLASH_ACR);
+   uint32 val = FLASH_READ_ACR();
 
-   acr &= ACR_PRFTBE;
-   acr |= ACR_PRFTBE_ENABLE;
+   val |= ACR_PRFTBE_ENABLE;
 
-   __write(FLASH_ACR, acr);
+   FLASH_WRITE_ACR(val);
 }
 
-void flash_set_latency(void) {
-   uint32 acr = __read(FLASH_ACR);
 
-   acr &= ACR_LATENCY;
-   acr |= ACR_LATENCY_2;
+/**
+ * @brief set flash wait states
+ * @param number of wait states
+ */
+void flash_set_latency(uint32 wait_states) {
+   uint32 val = FLASH_READ_ACR();
+
+   val &= ~ACR_LATENCY;
+   val |= wait_states;
 
-   __write(FLASH_ACR, acr);
+   FLASH_WRITE_ACR(val);
 }
diff --git a/libmaple/flash.h b/libmaple/flash.h
index dca5984..a1ae0a4 100644
--- a/libmaple/flash.h
+++ b/libmaple/flash.h
@@ -24,17 +24,26 @@
 
 
 /**
- *  @brief 
+ *  @brief basic stm32 flash setup routines
  */
 
 #ifndef _FLASH_H_
 #define _FLASH_H_
 
-#define FLASH_BASE              0x40022000
-#define FLASH_ACR               FLASH_BASE
+#define FLASH_WAIT_STATE_0              0x0
+#define FLASH_WAIT_STATE_1              0x1
+#define FLASH_WAIT_STATE_2              0x2
+
+#ifdef __cplusplus
+extern "C"{
+#endif
 
 void flash_enable_prefetch(void);
-void flash_set_latency(void);
+void flash_set_latency(uint32 wait_states);
+
+#ifdef __cplusplus
+}
+#endif
 
 #endif
 
diff --git a/libmaple/rcc.c b/libmaple/rcc.c
index 079c4d6..bb423b9 100644
--- a/libmaple/rcc.c
+++ b/libmaple/rcc.c
@@ -116,14 +116,6 @@ static void hse_init(void) {
 
 void rcc_init(void) {
    hse_init();
-
-   /* Leave this here for now...  */
-   /* Enable Prefetch Buffer */
-   flash_enable_prefetch();
-
-   /* Flash 2 wait state */
-   flash_set_latency();
-
    set_ahb_prescaler(SYSCLK_DIV_1);
    set_apb1_prescaler(HCLK_DIV_2);
    set_apb2_prescaler(HCLK_DIV_1);
diff --git a/wirish/wirish.c b/wirish/wirish.c
index e21f792..e166455 100644
--- a/wirish/wirish.c
+++ b/wirish/wirish.c
@@ -32,9 +32,15 @@
 #include "gpio.h"
 #include "nvic.h"
 #include "usb.h"
+#include "flash.h"
 
 void init(void) {
+   /* make sure the flash is ready before spinning the high speed clock up */
+   flash_enable_prefetch();
+   flash_set_latency(FLASH_WAIT_STATE_2);
+
    rcc_init();
+
    nvic_init();
    systick_init();
    gpio_init();