boards/xtensa/esp32s3/esp32s3-xiao: add SD card support over SPI2

[FelipeMdeO]

The XIAO ESP32-S3 Sense's onboard microSD slot (Seeed XIAOML Kit) is wired to SPI2 through the GPIO matrix: SCK=GPIO7, MOSI=GPIO9, MISO=GPIO8 (confirmed against espressif/arduino-esp32's XIAO_ESP32S3/pins_arduino.h) and CS=GPIO21 (confirmed against this project's own working xiaoml_bench_logger.ino, which tries CS candidates {21, 3} in that order -- GPIO3 is a documented fallback, not the real pin; a Seeed wiki page that names GPIO3 as CS turned out to be wrong and was the initial, unsuccessful attempt here).

Wires up board_sdmmc_spi_initialize() (common esp32s3 board code, CONFIG_MMCSD_SPI) into this board's bringup, and adds the esp32s3_spi2_status() callback (SPI_STATUS_PRESENT for SPIDEV_MMCSD(0)) that esp32s3-devkit and other in-tree boards already provide -- the esp32s3-xiao board had no SPI board file at all before this.

Validated on the bench: CMD0/CMD41/CMD58 handshake succeeds, SD ver2 card identified (SanDisk 32GB, 62333952 sectors), mounts as vfat, survives umount+remount with a written file intact.

Needed board defconfig additions (not included in this NuttX-tree commit; see the 61680_FW project repo for the board config that turns this on):

  CONFIG_ESP32S3_SPI2=y
  CONFIG_ESP32S3_SPI2_CSPIN=21
  CONFIG_ESP32S3_SPI2_CLKPIN=7
  CONFIG_ESP32S3_SPI2_MOSIPIN=9
  CONFIG_ESP32S3_SPI2_MISOPIN=8
  CONFIG_MMCSD=y
  CONFIG_NSH_MMCSDSPIPORTNO=2
  CONFIG_FS_FAT=y
  CONFIG_FAT_LFN=y
  CONFIG_FAT_LCNAMES=y

• Real Testing

nsh> mount -t vfat /dev/mmcsd0 /mnt
fat_checkbootrecord: WARNING: Signature: aa55 FS sectorsize: 0 HW sectorsize: 512
nsh> mount
  /etc type romfs
  /mnt type vfat
  /proc type procfs
nsh> echo "hello sd card MY_FW" > /mnt/test.txt
nsh> ls -l /mnt
/mnt:
 drw-rw-rw-           0 RUN00001/
 drw-rw-rw-           0 RUN00002/
 drw-rw-rw-           0 RUN00003/
 -rw-rw-rw-          23 test.txt
 drw-rw-rw-           0 System Volume Information/
nsh> cat /mnt/test.txt
hello sd card MY_FW
nsh> umount /mnt
nsh> mount -t vfat /dev/mmcsd0 /mnt
fat_checkbootrecord: WARNING: Signature: aa55 FS sectorsize: 0 HW sectorsize: 512
nsh> cat /mnt/test.txt
hello sd card MY_FW

[github-actions]

MemBrowse Memory Report

No memory changes detected for:

• arduino-mega2560
• esp32-devkitc
• hifive1-revb
• mirtoo
• qemu-armv8a
• qemu-intel64
• rx65n-rsk2mb
• s698pm-dkit
• stm32-nucleo-f103rb