stm32/sdcard: Add config option to force MM card capacity.

The current ST HAL does not support reading the extended CSD so cannot
correctly detect the capacity of high-capacity cards.  As a workaround, the
capacity can be forced via the MICROPY_HW_MMCARD_LOG_BLOCK_NBR config
option.
Signed-off-by: Damien George <damien@micropython.org>

ports/stm32/boards/PYBD_SF2/mpconfigboard.h

@@ -181,6 +181,9 @@ extern struct _spi_bdev_t spi_bdev2;
 #define MICROPY_HW_SDCARD_DETECT_PRESENT    (GPIO_PIN_RESET)
 #define MICROPY_HW_SDCARD_MOUNT_AT_BOOT     (0)
 
+// MM card: the size is hard-coded to support the WBUS-EMMC add-on
+#define MICROPY_HW_MMCARD_LOG_BLOCK_NBR     (7469056 + 2048)
+
 // USB config
 #define MICROPY_HW_USB_FS           (1)
 #define MICROPY_HW_USB_HS           (1)

ports/stm32/sdcard.c

@@ -309,8 +309,12 @@ STATIC HAL_StatusTypeDef sdmmc_init_mmc(void) {
         return status;
     }
 
-    // As this is an eMMC card, overwrite LogBlockNbr with actual value
-    sdmmc_handle.mmc.MmcCard.LogBlockNbr = 7469056 + 2048;
+    #ifdef MICROPY_HW_MMCARD_LOG_BLOCK_NBR
+    // A board can override the number of logical blocks (card capacity) if needed.
+    // This is needed when a card is high capacity because the extended CSD command
+    // is not supported by the current version of the HAL.
+    sdmmc_handle.mmc.MmcCard.LogBlockNbr = MICROPY_HW_MMCARD_LOG_BLOCK_NBR;
+    #endif
 
     #if MICROPY_HW_SDCARD_BUS_WIDTH >= 4
     // Configure the SDIO bus width for 4/8-bit wide operation