adamksmith
a911b9e4cb
ESPHome external_component that presents a synthetic 64 KB FAT12 disk over the ESP32-S3's native USB-OTG, containing a one-byte switch_position file and a switch_position_grub.cfg snippet. The disk's volume serial is fixed at 0x55AA6922 to stay drop-in compatible with the upstream /etc/grub.d hook. Components: - fat12 / msc_disk: portable FAT12 sector synthesiser ported from reference/src/fat.c and the boot-sector / FAT / dir-entry generation in reference/src/usb.c. - usb_descriptors / tusb_glue: TinyUSB MSC class with our own callbacks delegating to MscDisk::read_lba (linker --allow-multiple-definition picks ours over esp_tinyusb's storage-backed defaults). - grub_boot_switch: top-level Component, NVS persistence on target changes, exposes targets table to sub-platforms. - select: HA-facing select platform reading parent's targets map. Validated end-to-end on an ESP32-S3-DevKitC-1: USB enumerates as 26ba:8003, /dev/sdb mounts FAT12, mtype reads back the live target, and POST /select/boot_target/set?option=Windows updates both files on the next host read.
60 lines
1.8 KiB
C++
60 lines
1.8 KiB
C++
// Host-side test harness for the FAT12 emulator.
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//
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// Builds a 64 KB disk image by walking LBAs 0..127 through MscDisk::read_lba,
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// then verifies it with mtools. We mimic the two virtual files the production
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// component installs in install_virtual_files_().
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//
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// Build with: make -C test
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#include "msc_disk.h"
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#include <cstdio>
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#include <cstdlib>
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#include <cstring>
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#include <fstream>
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#include <string>
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using esphome::grub_boot_switch::MscDisk;
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int main(int argc, char **argv) {
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const char *out_path = (argc > 1) ? argv[1] : "disk.img";
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const uint8_t target = (argc > 2) ? static_cast<uint8_t>(atoi(argv[2])) : 0;
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MscDisk disk;
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disk.set_volume_serial(0x55AA6922);
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disk.set_volume_label("SWITCH");
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disk.set_file_date(2026, 5, 4);
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static const char kPrefix[] = "set os_hw_switch=";
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static const size_t kPrefixLen = sizeof(kPrefix) - 1;
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static const size_t kFileLen = kPrefixLen + 2;
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disk.add_file("switch_position", "SWITCH~1", " ", 1,
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[target](uint8_t *out) { out[0] = '0' + (target % 10); });
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disk.add_file("switch_position_grub.cfg", "SWITCH~1", "CFG", kFileLen,
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[target](uint8_t *out) {
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memcpy(out, kPrefix, kPrefixLen);
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out[kPrefixLen] = '0' + (target % 10);
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out[kPrefixLen + 1] = '\n';
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});
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std::ofstream f(out_path, std::ios::binary);
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if (!f) {
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fprintf(stderr, "could not open %s\n", out_path);
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return 1;
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}
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uint8_t sector[512];
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for (uint32_t lba = 0; lba < disk.sector_count(); ++lba) {
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disk.read_lba(lba, sector);
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f.write(reinterpret_cast<const char *>(sector), sizeof(sector));
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}
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f.close();
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fprintf(stderr, "wrote %u sectors (%u bytes) to %s with target=%u\n",
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disk.sector_count(), disk.sector_count() * disk.sector_size(),
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out_path, target);
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return 0;
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}
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