stm32/boards/LEGO_HUB_NO6: Add support for mboot to access SPI flash.

The following changes are made:
- Use software SPI for external SPI flash access when building mboot.
- Enable the mboot filesystem-loading feature, with FAT FS support.
- Increase the frequency of the CPU when in mboot to 96MHz, to increase the
  speed of SPI flash accesses and programming.
Signed-off-by: Damien George <damien@micropython.org>

ports/stm32/boards/LEGO_HUB_NO6/bdev.c

@@ -3,7 +3,7 @@
  *
  * The MIT License (MIT)
  *
- * Copyright (c) 2021 Damien P. George
+ * Copyright (c) 2021-2022 Damien P. George
  *
  * Permission is hereby granted, free of charge, to any person obtaining a copy
  * of this software and associated documentation files (the "Software"), to deal
@@ -28,6 +28,30 @@
 #include "storage.h"
 #include "spi.h"
 
+#if BUILDING_MBOOT
+
+// Mboot doesn't support hardware SPI, so use software SPI instead.
+
+STATIC const mp_soft_spi_obj_t soft_spi_bus = {
+    .delay_half = MICROPY_HW_SOFTSPI_MIN_DELAY,
+    .polarity = 0,
+    .phase = 0,
+    .sck = MICROPY_HW_SPIFLASH_SCK,
+    .mosi = MICROPY_HW_SPIFLASH_MOSI,
+    .miso = MICROPY_HW_SPIFLASH_MISO,
+};
+
+const mp_spiflash_config_t board_mboot_spiflash_config = {
+    .bus_kind = MP_SPIFLASH_BUS_SPI,
+    .bus.u_spi.cs = MICROPY_HW_SPIFLASH_CS,
+    .bus.u_spi.data = (void *)&soft_spi_bus,
+    .bus.u_spi.proto = &mp_soft_spi_proto,
+};
+
+mp_spiflash_t board_mboot_spiflash;
+
+#else
+
 STATIC const spi_proto_cfg_t spi_bus = {
     .spi = &spi_obj[1], // SPI2 hardware peripheral
     .baudrate = 25000000,
@@ -48,3 +72,5 @@ const mp_spiflash_config_t spiflash_config = {
 };
 
 spi_bdev_t spi_bdev;
+
+#endif

ports/stm32/boards/LEGO_HUB_NO6/mpconfigboard.h

@@ -123,8 +123,27 @@
 /******************************************************************************/
 // Bootloader configuration
 
+// Configure CPU frequency to 96MHz, to make updates from SPI flash faster
+#define MBOOT_CLK_PLLM                           (MICROPY_HW_CLK_VALUE / 1000000)
+#define MBOOT_CLK_PLLN                           (192)
+#define MBOOT_CLK_PLLP                           (RCC_PLLP_DIV2)
+#define MBOOT_CLK_PLLQ                           (4)
+#define MBOOT_CLK_AHB_DIV                        (RCC_SYSCLK_DIV1)
+#define MBOOT_CLK_APB1_DIV                       (RCC_HCLK_DIV4)
+#define MBOOT_CLK_APB2_DIV                       (RCC_HCLK_DIV2)
+#define MBOOT_FLASH_LATENCY                      FLASH_LATENCY_3
+
+#define MBOOT_FSLOAD                             (1)
+#define MBOOT_VFS_FAT                            (1)
 #define MBOOT_LEAVE_BOOTLOADER_VIA_RESET         (0)
 
+#define MBOOT_SPIFLASH_ADDR                      (0x80000000)
+#define MBOOT_SPIFLASH_BYTE_SIZE                 (32 * 1024 * 1024)
+#define MBOOT_SPIFLASH_LAYOUT                    "/0x80000000/8192*4Kg"
+#define MBOOT_SPIFLASH_ERASE_BLOCKS_PER_PAGE     (1)
+#define MBOOT_SPIFLASH_SPIFLASH                  (&board_mboot_spiflash)
+#define MBOOT_SPIFLASH_CONFIG                    (&board_mboot_spiflash_config)
+
 #define MBOOT_LED1                               0
 #define MBOOT_BOARD_LED_INIT                     board_mboot_led_init
 #define MBOOT_BOARD_LED_STATE                    board_mboot_led_state
@@ -138,6 +157,8 @@
 
 extern const struct _mp_spiflash_config_t spiflash_config;
 extern struct _spi_bdev_t spi_bdev;
+extern const struct _mp_spiflash_config_t board_mboot_spiflash_config;
+extern struct _mp_spiflash_t board_mboot_spiflash;
 
 void board_init(void);
 void board_mboot_cleanup(int reset_mode);