stm32/flash: Make flash C-API reusable, and funcs return an error code.

This commit makes the low-level flash C functions usable by code other than
flashbdev.c (eg by mboot).  Changes in this commit are:
- flash_erase() and flash_write() now return an errno error code, a
  negative value on error.
- flash_erase() now automatically locks the flash, as well as unlocking it.
- flash_write() now automatically unlocks the flash, as well as locking it.
- flashbdev.c is modified for the above changes.

Signed-off-by: Damien George <damien@micropython.org>

ports/stm32/flash.c

@@ -26,6 +26,7 @@
 
 #include "py/mpconfig.h"
 #include "py/misc.h"
+#include "py/mphal.h"
 #include "flash.h"
 
 typedef struct {
@@ -162,17 +163,18 @@ uint32_t flash_get_sector_info(uint32_t addr, uint32_t *start_addr, uint32_t *si
     return 0;
 }
 
-void flash_erase(uint32_t flash_dest, uint32_t num_word32) {
+int flash_erase(uint32_t flash_dest, uint32_t num_word32) {
     // check there is something to write
     if (num_word32 == 0) {
-        return;
+        return 0;
     }
 
-    // unlock
+    // Unlock the flash for erase.
     HAL_FLASH_Unlock();
 
-    FLASH_EraseInitTypeDef EraseInitStruct;
+    // Clear pending flags (if any) and set up EraseInitStruct.
 
+    FLASH_EraseInitTypeDef EraseInitStruct;
     #if defined(STM32F0)
     __HAL_FLASH_CLEAR_FLAG(FLASH_FLAG_EOP | FLASH_FLAG_WRPERR | FLASH_FLAG_PGERR);
     EraseInitStruct.TypeErase = FLASH_TYPEERASE_PAGES;
@@ -190,17 +192,14 @@ void flash_erase(uint32_t flash_dest, uint32_t num_word32) {
     EraseInitStruct.NbPages = (4 * num_word32 + FLASH_PAGE_SIZE - 4) / FLASH_PAGE_SIZE;
     #elif defined(STM32L4)
     __HAL_FLASH_CLEAR_FLAG(FLASH_FLAG_ALL_ERRORS);
-
-    // erase the sector(s)
     // The sector returned by flash_get_sector_info can not be used
     // as the flash has on each bank 0/1 pages 0..255
     EraseInitStruct.TypeErase = FLASH_TYPEERASE_PAGES;
     EraseInitStruct.Banks = get_bank(flash_dest);
     EraseInitStruct.Page = get_page(flash_dest);
     EraseInitStruct.NbPages = get_page(flash_dest + 4 * num_word32 - 1) - EraseInitStruct.Page + 1;
-    ;
     #else
-    // Clear pending flags (if any)
+
     #if defined(STM32H7)
     __HAL_FLASH_CLEAR_FLAG(FLASH_FLAG_ALL_ERRORS_BANK1 | FLASH_FLAG_ALL_ERRORS_BANK2);
     #else
@@ -208,7 +207,6 @@ void flash_erase(uint32_t flash_dest, uint32_t num_word32) {
         FLASH_FLAG_PGAERR | FLASH_FLAG_PGPERR | FLASH_FLAG_PGSERR);
     #endif
 
-    // erase the sector(s)
     EraseInitStruct.TypeErase = TYPEERASE_SECTORS;
     EraseInitStruct.VoltageRange = VOLTAGE_RANGE_3; // voltage range needs to be 2.7V to 3.6V
     #if defined(STM32H7)
@@ -216,14 +214,17 @@ void flash_erase(uint32_t flash_dest, uint32_t num_word32) {
     #endif
     EraseInitStruct.Sector = flash_get_sector_info(flash_dest, NULL, NULL);
     EraseInitStruct.NbSectors = flash_get_sector_info(flash_dest + 4 * num_word32 - 1, NULL, NULL) - EraseInitStruct.Sector + 1;
+
     #endif
 
+    // Erase the sectors.
     uint32_t SectorError = 0;
-    if (HAL_FLASHEx_Erase(&EraseInitStruct, &SectorError) != HAL_OK) {
-        // error occurred during sector erase
-        HAL_FLASH_Lock(); // lock the flash
-        return;
-    }
+    HAL_StatusTypeDef status = HAL_FLASHEx_Erase(&EraseInitStruct, &SectorError);
+
+    // Lock the flash after erase.
+    HAL_FLASH_Lock();
+
+    return mp_hal_status_to_neg_errno(status);
 }
 
 /*
@@ -255,16 +256,21 @@ void flash_erase_it(uint32_t flash_dest, uint32_t num_word32) {
 }
 */
 
-void flash_write(uint32_t flash_dest, const uint32_t *src, uint32_t num_word32) {
+int flash_write(uint32_t flash_dest, const uint32_t *src, uint32_t num_word32) {
+    // Unlock the flash for write.
+    HAL_FLASH_Unlock();
+
+    HAL_StatusTypeDef status = HAL_OK;
+
     #if defined(STM32L4) || defined(STM32WB)
 
     // program the flash uint64 by uint64
     for (int i = 0; i < num_word32 / 2; i++) {
         uint64_t val = *(uint64_t *)src;
-        if (HAL_FLASH_Program(FLASH_TYPEPROGRAM_DOUBLEWORD, flash_dest, val) != HAL_OK) {
-            // error occurred during flash write
-            HAL_FLASH_Lock(); // lock the flash
-            return;
+        status = HAL_FLASH_Program(FLASH_TYPEPROGRAM_DOUBLEWORD, flash_dest, val);
+        if (status != HAL_OK) {
+            num_word32 = 0; // don't write any odd word after this loop
+            break;
         }
         flash_dest += 8;
         src += 2;
@@ -272,21 +278,16 @@ void flash_write(uint32_t flash_dest, const uint32_t *src, uint32_t num_word32)
     if ((num_word32 & 0x01) == 1) {
         uint64_t val = *(uint64_t *)flash_dest;
         val = (val & 0xffffffff00000000uL) | (*src);
-        if (HAL_FLASH_Program(FLASH_TYPEPROGRAM_DOUBLEWORD, flash_dest, val) != HAL_OK) {
-            // error occurred during flash write
-            HAL_FLASH_Lock(); // lock the flash
-            return;
-        }
+        status = HAL_FLASH_Program(FLASH_TYPEPROGRAM_DOUBLEWORD, flash_dest, val);
     }
 
     #elif defined(STM32H7)
 
     // program the flash 256 bits at a time
     for (int i = 0; i < num_word32 / 8; i++) {
-        if (HAL_FLASH_Program(FLASH_TYPEPROGRAM_FLASHWORD, flash_dest, (uint64_t)(uint32_t)src) != HAL_OK) {
-            // error occurred during flash write
-            HAL_FLASH_Lock(); // lock the flash
-            return;
+        status = HAL_FLASH_Program(FLASH_TYPEPROGRAM_FLASHWORD, flash_dest, (uint64_t)(uint32_t)src);
+        if (status != HAL_OK) {
+            break;
         }
         flash_dest += 32;
         src += 8;
@@ -296,10 +297,9 @@ void flash_write(uint32_t flash_dest, const uint32_t *src, uint32_t num_word32)
 
     // program the flash word by word
     for (int i = 0; i < num_word32; i++) {
-        if (HAL_FLASH_Program(FLASH_TYPEPROGRAM_WORD, flash_dest, *src) != HAL_OK) {
-            // error occurred during flash write
-            HAL_FLASH_Lock(); // lock the flash
-            return;
+        status = HAL_FLASH_Program(FLASH_TYPEPROGRAM_WORD, flash_dest, *src);
+        if (status != HAL_OK) {
+            break;
         }
         flash_dest += 4;
         src += 1;
@@ -307,8 +307,10 @@ void flash_write(uint32_t flash_dest, const uint32_t *src, uint32_t num_word32)
 
     #endif
 
-    // lock the flash
+    // Lock the flash after write.
     HAL_FLASH_Lock();
+
+    return mp_hal_status_to_neg_errno(status);
 }
 
 /*

ports/stm32/flash.h

@@ -27,7 +27,7 @@
 #define MICROPY_INCLUDED_STM32_FLASH_H
 
 uint32_t flash_get_sector_info(uint32_t addr, uint32_t *start_addr, uint32_t *size);
-void flash_erase(uint32_t flash_dest, uint32_t num_word32);
-void flash_write(uint32_t flash_dest, const uint32_t *src, uint32_t num_word32);
+int flash_erase(uint32_t flash_dest, uint32_t num_word32);
+int flash_write(uint32_t flash_dest, const uint32_t *src, uint32_t num_word32);
 
 #endif // MICROPY_INCLUDED_STM32_FLASH_H

ports/stm32/mphalport.h

@@ -4,6 +4,10 @@
 
 extern const unsigned char mp_hal_status_to_errno_table[4];
 
+static inline int mp_hal_status_to_neg_errno(HAL_StatusTypeDef status) {
+    return -mp_hal_status_to_errno_table[status];
+}
+
 NORETURN void mp_hal_raise(HAL_StatusTypeDef status);
 void mp_hal_set_interrupt_char(int c); // -1 to disable