mirror of
https://github.com/tillitis/tillitis-key1.git
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fw: Introduce an explicit state machine - changes protocol!
We introduce an explicit state machine (see README). With the new states we: - combine setting size and USS to a single command. - start the device app immediatiely when having receceived the last data chunk and returning the digest. - Loop forever and wait for the stick to be removed if we end up in unknown state. Signed-off-by: Michael Cardell Widerkrantz <mc@tillitis.se>
This commit is contained in:
Michael Cardell Widerkrantz
parent
2fa1ffb8e7
commit
c80dc53027
@ -18,6 +18,54 @@ If your available `objcopy` and `size` commands is anything other than
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the default `llvm-objcopy` and `llvm-size` define `OBJCOPY` and `SIZE`
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to whatever they're called on your system.
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## Firmware state machine
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States:
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- `initial` - At start.
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- `init_loading` - Reset app digest, size, `USS` and load address.
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- `loading` - Expect more app data or a reset by `LoadApp()`.
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- `run` - Computes CDI and starts the device app.
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Commands in state `initial`:
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| *command* | *next state* |
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|--------------------|----------------|
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| NameVersion() | unchanged |
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| GetUDI() | unchanged |
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| LoadApp(size, uss) | `init_loading` |
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| | |
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Commands in `init_loading`:
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| *command* | *next state* |
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|--------------------|----------------|
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| NameVersion() | unchanged |
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| GetUDI() | unchanged |
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| LoadApp(size, uss) | `init_loading` |
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| LoadAppData(data) | `loading` |
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| | |
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Commands in `loading`:
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| *command* | *next state* |
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|--------------------|----------------------------------|
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| NameVersion() | unchanged |
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| GetUDI() | unchanged |
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| LoadApp(size, uss) | `init_loading` |
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| LoadAppData(data) | `loading` or `run` on last chunk |
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| | |
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Behaviour:
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- NameVersion: identifies stick.
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- GetUDI: returns the Unique Device ID with vendor id, product id,
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revision, serial number.
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- LoadApp(size, uss): Start loading an app with this size and user
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supplied secret.
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- LoadAppData(data): Load chunk of data of app. When last data chunk
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is received we compute and return the digest.
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## Using QEMU
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Checkout the `tk1` branch of [our version of the
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@ -60,9 +60,10 @@ static void print_digest(uint8_t *md)
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}
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// CDI = blake2s(uds, blake2s(app), uss)
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static void compute_cdi(uint8_t digest[32], uint8_t uss[32])
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static void compute_cdi(uint8_t digest[32], uint8_t use_uss, uint8_t uss[32])
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{
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uint32_t local_cdi[8];
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int len;
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// To protect UDS we use a special firmware-only RAM for both
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// the in parameter to blake2s and the blake2s context.
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@ -70,11 +71,16 @@ static void compute_cdi(uint8_t digest[32], uint8_t uss[32])
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// Only word aligned access to UDS
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wordcpy((void *)fw_ram, (void *)uds, 8);
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memcpy((void *)fw_ram + 32, digest, 32);
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memcpy((void *)fw_ram + 64, uss, 32);
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if (use_uss != 0) {
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memcpy((void *)fw_ram + 64, uss, 32);
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len = 96;
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} else {
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len = 64;
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}
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blake2s_ctx *secure_ctx = (blake2s_ctx *)(fw_ram + 96);
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blake2s_ctx *secure_ctx = (blake2s_ctx *)(fw_ram + len);
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blake2s((void *)local_cdi, 32, NULL, 0, (const void *)fw_ram, 96,
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blake2s((void *)local_cdi, 32, NULL, 0, (const void *)fw_ram, len,
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secure_ctx);
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// Write over the firmware-only RAM
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@ -84,6 +90,13 @@ static void compute_cdi(uint8_t digest[32], uint8_t uss[32])
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wordcpy((void *)cdi, (void *)local_cdi, 8);
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}
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enum state {
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FW_STATE_INITIAL,
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FW_STATE_INIT_LOADING,
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FW_STATE_LOADING,
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FW_STATE_RUN
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};
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int main()
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{
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uint32_t local_name0 = *name0;
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@ -94,179 +107,34 @@ int main()
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uint8_t rsp[CMDLEN_MAXBYTES];
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uint8_t *loadaddr = (uint8_t *)TK1_APP_ADDR;
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int left = 0; // Bytes left to receive
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uint8_t use_uss = FALSE;
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uint8_t uss[32] = {0};
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uint8_t digest[32] = {0};
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enum state state = FW_STATE_INITIAL;
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print_hw_version(local_name0, local_name1, local_ver);
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for (;;) {
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// blocking; fw flashing white while waiting for cmd
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uint8_t in = readbyte_ledflash(LED_WHITE, 800000);
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if (parseframe(in, &hdr) == -1) {
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puts("Couldn't parse header\n");
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continue;
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}
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memset(cmd, 0, CMDLEN_MAXBYTES);
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// Read firmware command: Blocks!
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read(cmd, hdr.len);
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// Is it for us?
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if (hdr.endpoint != DST_FW) {
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puts("Message not meant for us\n");
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continue;
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}
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// Reset response buffer
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memset(rsp, 0, CMDLEN_MAXBYTES);
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// Min length is 1 byte so this should always be here
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switch (cmd[0]) {
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case FW_CMD_NAME_VERSION:
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puts("cmd: name-version\n");
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if (hdr.len != 1) {
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// Bad length - give them an empty response
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fwreply(hdr, FW_RSP_NAME_VERSION, rsp);
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break;
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}
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memcpy(rsp, (uint8_t *)&local_name0, 4);
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memcpy(rsp + 4, (uint8_t *)&local_name1, 4);
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memcpy(rsp + 8, (uint8_t *)&local_ver, 4);
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fwreply(hdr, FW_RSP_NAME_VERSION, rsp);
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switch (state) {
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case FW_STATE_INITIAL:
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break;
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case FW_CMD_GET_UDI:
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puts("FW_CMD_GET_UDI\n");
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if (hdr.len != 1) {
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// Bad cmd length
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rsp[0] = STATUS_BAD;
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fwreply(hdr, FW_RSP_GET_UDI, rsp);
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break;
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}
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rsp[0] = STATUS_OK;
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uint32_t udi_words[2];
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wordcpy(udi_words, (void *)udi, 2);
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memcpy(rsp + 1, udi_words, 2 * 4);
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fwreply(hdr, FW_RSP_GET_UDI, rsp);
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break;
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case FW_CMD_LOAD_USS:
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puts("cmd: load-uss\n");
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if (hdr.len != 128) {
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// Bad cmd length
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rsp[0] = STATUS_BAD;
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fwreply(hdr, FW_RSP_LOAD_USS, rsp);
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break;
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}
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memcpy(uss, cmd + 1, 32);
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rsp[0] = STATUS_OK;
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fwreply(hdr, FW_RSP_LOAD_USS, rsp);
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break;
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case FW_CMD_LOAD_APP_SIZE:
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puts("cmd: load-app-size\n");
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if (hdr.len != 32) {
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// Bad length
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rsp[0] = STATUS_BAD;
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fwreply(hdr, FW_RSP_LOAD_APP_SIZE, rsp);
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break;
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}
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// cmd[1..4] contains the size.
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uint32_t local_app_size = cmd[1] + (cmd[2] << 8) +
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(cmd[3] << 16) +
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(cmd[4] << 24);
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puts("app size: ");
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putinthex(local_app_size);
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lf();
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if (local_app_size > TK1_APP_MAX_SIZE) {
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rsp[0] = STATUS_BAD;
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fwreply(hdr, FW_RSP_LOAD_APP_SIZE, rsp);
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break;
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}
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*app_size = local_app_size;
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case FW_STATE_INIT_LOADING:
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*app_addr = 0;
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// Clear digest as GET_APP_DIGEST returns it even if it
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// has not been calculated
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memset(digest, 0, 32);
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left = *app_size;
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// Reset where to start loading the program
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loadaddr = (uint8_t *)TK1_APP_ADDR;
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left = *app_size;
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rsp[0] = STATUS_OK;
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fwreply(hdr, FW_RSP_LOAD_APP_SIZE, rsp);
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break;
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case FW_CMD_LOAD_APP_DATA:
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puts("cmd: load-app-data\n");
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if (hdr.len != 128 || *app_size == 0 ||
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*app_addr != 0) {
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// Bad length, or app_size not yet set, or
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// app_addr already set (fully loaded!)
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rsp[0] = STATUS_BAD;
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fwreply(hdr, FW_RSP_LOAD_APP_DATA, rsp);
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break;
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}
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int nbytes;
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if (left > 127) {
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nbytes = 127;
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} else {
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nbytes = left;
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}
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memcpy(loadaddr, cmd + 1, nbytes);
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loadaddr += nbytes;
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left -= nbytes;
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if (left == 0) {
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puts("Fully loaded ");
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putinthex(*app_size);
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lf();
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*app_addr = TK1_APP_ADDR;
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// Get the Blake2S digest of the app - store it
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// for later queries
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blake2s_ctx ctx;
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blake2s(digest, 32, NULL, 0,
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(const void *)*app_addr, *app_size,
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&ctx);
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print_digest(digest);
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// CDI = hash(uds, hash(app), uss)
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compute_cdi(digest, uss);
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}
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rsp[0] = STATUS_OK;
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fwreply(hdr, FW_RSP_LOAD_APP_DATA, rsp);
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case FW_STATE_LOADING:
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break;
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case FW_CMD_RUN_APP:
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puts("cmd: run-app\n");
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case FW_STATE_RUN:
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*app_addr = TK1_APP_ADDR;
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if (hdr.len != 1 || *app_size == 0 || *app_addr == 0) {
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// Bad cmd length, or app_size or app_addr are
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// not yet set
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rsp[0] = STATUS_BAD;
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fwreply(hdr, FW_RSP_RUN_APP, rsp);
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break;
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}
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rsp[0] = STATUS_OK;
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fwreply(hdr, FW_RSP_RUN_APP, rsp);
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// CDI = hash(uds, hash(app), uss)
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compute_cdi(digest, use_uss, uss);
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// Flip over to application mode
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*switch_app = 1;
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@ -293,11 +161,160 @@ int main()
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// clang-format on
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break; // This is never reached!
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case FW_CMD_GET_APP_DIGEST:
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puts("cmd: get-app-digest\n");
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default:
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// Unknown state!?
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puts("Unknown firmware state 0x");
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puthex(state);
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lf();
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memcpy(rsp, &digest, 32);
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fwreply(hdr, FW_RSP_GET_APP_DIGEST, rsp);
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asm volatile("forever:;"
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"j forever;");
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break; // Not reached
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}
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// blocking; fw flashing white while waiting for cmd
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uint8_t in = readbyte_ledflash(LED_WHITE, 800000);
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if (parseframe(in, &hdr) == -1) {
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puts("Couldn't parse header\n");
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continue;
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}
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memset(cmd, 0, CMDLEN_MAXBYTES);
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// Now we know the size of the cmd frame, read it all
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read(cmd, hdr.len);
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// Is it for us?
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if (hdr.endpoint != DST_FW) {
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puts("Message not meant for us\n");
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continue;
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}
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// Reset response buffer
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memset(rsp, 0, CMDLEN_MAXBYTES);
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// Min length is 1 byte so this should always be here
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switch (cmd[0]) {
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case FW_CMD_NAME_VERSION:
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puts("cmd: name-version\n");
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if (hdr.len != 1) {
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// Bad length - give them an empty response
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fwreply(hdr, FW_RSP_NAME_VERSION, rsp);
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break;
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}
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memcpy(rsp, (uint8_t *)&local_name0, 4);
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memcpy(rsp + 4, (uint8_t *)&local_name1, 4);
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memcpy(rsp + 8, (uint8_t *)&local_ver, 4);
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fwreply(hdr, FW_RSP_NAME_VERSION, rsp);
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// state unchanged
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break;
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case FW_CMD_GET_UDI:
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puts("cmd: get-udi\n");
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if (hdr.len != 1) {
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// Bad cmd length
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rsp[0] = STATUS_BAD;
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fwreply(hdr, FW_RSP_GET_UDI, rsp);
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break;
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}
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rsp[0] = STATUS_OK;
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uint32_t udi_words[2];
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wordcpy(udi_words, (void *)udi, 2);
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memcpy(rsp + 1, udi_words, 2 * 4);
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fwreply(hdr, FW_RSP_GET_UDI, rsp);
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// state unchanged
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break;
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case FW_CMD_LOAD_APP:
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puts("cmd: load-app(size, uss)\n");
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if (hdr.len != 128) {
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// Bad length
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rsp[0] = STATUS_BAD;
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fwreply(hdr, FW_RSP_LOAD_APP, rsp);
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break;
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}
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// cmd[1..4] contains the size.
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uint32_t local_app_size = cmd[1] + (cmd[2] << 8) +
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(cmd[3] << 16) +
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(cmd[4] << 24);
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puts("app size: ");
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putinthex(local_app_size);
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lf();
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if (local_app_size > TK1_APP_MAX_SIZE) {
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rsp[0] = STATUS_BAD;
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fwreply(hdr, FW_RSP_LOAD_APP, rsp);
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break;
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}
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*app_size = local_app_size;
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// Do we have a USS at all?
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if (cmd[5] != 0) {
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// Yes
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use_uss = TRUE;
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memcpy(uss, cmd + 6, 32);
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} else {
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use_uss = FALSE;
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}
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rsp[0] = STATUS_OK;
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fwreply(hdr, FW_RSP_LOAD_APP, rsp);
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state = FW_STATE_INIT_LOADING;
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break;
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case FW_CMD_LOAD_APP_DATA:
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puts("cmd: load-app-data\n");
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if (hdr.len != 128 || (state != FW_STATE_INIT_LOADING &&
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state != FW_STATE_LOADING)) {
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// Bad cmd length or state
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rsp[0] = STATUS_BAD;
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fwreply(hdr, FW_RSP_LOAD_APP_DATA, rsp);
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break;
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}
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int nbytes;
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if (left > 127) {
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nbytes = 127;
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} else {
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nbytes = left;
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}
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memcpy(loadaddr, cmd + 1, nbytes);
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loadaddr += nbytes;
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left -= nbytes;
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if (left == 0) {
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puts("Fully loaded ");
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putinthex(*app_size);
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lf();
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// Compute Blake2S digest of the app, storing
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// it for FW_STATE_RUN
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blake2s_ctx ctx;
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blake2s(digest, 32, NULL, 0,
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(const void *)TK1_APP_ADDR, *app_size,
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&ctx);
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print_digest(digest);
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// And return the digest in final response
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rsp[0] = STATUS_OK;
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memcpy(&rsp[1], &digest, 32);
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fwreply(hdr, FW_RSP_LOAD_APP_DATA_READY, rsp);
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state = FW_STATE_RUN;
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break;
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}
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rsp[0] = STATUS_OK;
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fwreply(hdr, FW_RSP_LOAD_APP_DATA, rsp);
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state = FW_STATE_LOADING;
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break;
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default:
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@ -71,12 +71,7 @@ void fwreply(struct frame_header hdr, enum fwcmd rspcode, uint8_t *buf)
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nbytes = 32;
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break;
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case FW_RSP_LOAD_USS:
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len = LEN_4;
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nbytes = 4;
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break;
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case FW_RSP_LOAD_APP_SIZE:
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case FW_RSP_LOAD_APP:
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len = LEN_4;
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nbytes = 4;
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break;
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@ -86,12 +81,7 @@ void fwreply(struct frame_header hdr, enum fwcmd rspcode, uint8_t *buf)
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nbytes = 4;
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break;
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case FW_RSP_RUN_APP:
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len = LEN_4;
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nbytes = 4;
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break;
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case FW_RSP_GET_APP_DIGEST:
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case FW_RSP_LOAD_APP_DATA_READY:
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len = LEN_128;
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nbytes = 128;
|
||||
break;
|
||||
|
||||
@ -26,21 +26,15 @@ enum cmdlen {
|
||||
|
||||
// clang-format off
|
||||
enum fwcmd {
|
||||
FW_CMD_NAME_VERSION = 0x01,
|
||||
FW_RSP_NAME_VERSION = 0x02,
|
||||
FW_CMD_LOAD_APP_SIZE = 0x03,
|
||||
FW_RSP_LOAD_APP_SIZE = 0x04,
|
||||
FW_CMD_LOAD_APP_DATA = 0x05,
|
||||
FW_RSP_LOAD_APP_DATA = 0x06,
|
||||
FW_CMD_RUN_APP = 0x07,
|
||||
FW_RSP_RUN_APP = 0x08,
|
||||
FW_CMD_GET_APP_DIGEST = 0x09,
|
||||
FW_CMD_LOAD_USS = 0x0a,
|
||||
FW_RSP_LOAD_USS = 0x0b,
|
||||
FW_CMD_GET_UDI = 0x0c,
|
||||
FW_RSP_GET_UDI = 0x0d,
|
||||
/* ... */
|
||||
FW_RSP_GET_APP_DIGEST = 0x10, // encoded as 0x10 for backwards compatibility
|
||||
FW_CMD_NAME_VERSION = 0x01,
|
||||
FW_RSP_NAME_VERSION = 0x02,
|
||||
FW_CMD_LOAD_APP = 0x03,
|
||||
FW_RSP_LOAD_APP = 0x04,
|
||||
FW_CMD_LOAD_APP_DATA = 0x05,
|
||||
FW_RSP_LOAD_APP_DATA = 0x06,
|
||||
FW_RSP_LOAD_APP_DATA_READY = 0x07,
|
||||
FW_CMD_GET_UDI = 0x08,
|
||||
FW_RSP_GET_UDI = 0x09,
|
||||
};
|
||||
// clang-format on
|
||||
|
||||
|
||||
@ -16,4 +16,7 @@ typedef unsigned long size_t;
|
||||
|
||||
#define NULL ((char *)0)
|
||||
|
||||
#define FALSE 0
|
||||
#define TRUE !FALSE
|
||||
|
||||
#endif
|
||||
|
||||
Loading…
Reference in New Issue
Block a user