altos/stmf0: Add a comment about the requirements for using ao_flash_stm

[fw/altos] / src / stmf0 / ao_flash_stm.c

diff --git a/src/stmf0/ao_flash_stm.c b/src/stmf0/ao_flash_stm.c
index 2aeff3880fce13f3a91ec545276d8e9ab797538c..2d57eea72701eefeae6e61ad0a6fc0395cf2dac7 100644 (file)
--- a/src/stmf0/ao_flash_stm.c
+++ b/src/stmf0/ao_flash_stm.c
@@ -19,6 +19,12 @@
 #include <ao.h>
 #include <ao_flash.h>
 
+/* Note that the HSI clock must be running for this code to work.
+ * Also, special care must be taken with the linker to ensure that the
+ * functions marked 'ramtext' land in ram and not rom. An example of that
+ * can be found in altos-loader.ld
+ */
+
 static uint8_t
 ao_flash_is_locked(void)
 {
@@ -44,12 +50,7 @@ ao_flash_lock(void)
        stm_flash.cr |= (1 << STM_FLASH_CR_LOCK);
 }
 
-static void
-ao_flash_wait_bsy(void)
-{
-       while (stm_flash.sr & (1 << STM_FLASH_SR_BSY))
-               ;
-}
+#define ao_flash_wait_bsy() do { while (stm_flash.sr & (1 << STM_FLASH_SR_BSY)); } while (0)
 
 static void __attribute__ ((section(".ramtext"),noinline))
 _ao_flash_erase_page(uint32_t *page)