feat(core): allow SD card hotswap based on production date for Model T

core/.changelog.d/3940.added

@@ -0,0 +1 @@
+[T2T1] Allow SD card hotswap based on production date

core/embed/extmod/modtrezorutils/modtrezorutils.c

@@ -253,6 +253,16 @@ STATIC mp_obj_t mod_trezorutils_unit_btconly(void) {
 STATIC MP_DEFINE_CONST_FUN_OBJ_0(mod_trezorutils_unit_btconly_obj,
                                  mod_trezorutils_unit_btconly);
 
+/// def sd_hotswap_enabled() -> bool:
+///     """
+///     Returns True if SD card hot swapping is enabled
+///     """
+STATIC mp_obj_t mod_trezorutils_sd_hotswap_enabled(void) {
+  return unit_variant_is_sd_hotswap_enabled() ? mp_const_true : mp_const_false;
+}
+STATIC MP_DEFINE_CONST_FUN_OBJ_0(mod_trezorutils_sd_hotswap_enabled_obj,
+                                 mod_trezorutils_sd_hotswap_enabled);
+
 /// def reboot_to_bootloader(
 ///     boot_command : int = 0,
 ///     boot_args : bytes | None = None,
@@ -415,6 +425,8 @@ STATIC const mp_rom_map_elem_t mp_module_trezorutils_globals_table[] = {
      MP_ROM_PTR(&mod_trezorutils_unit_color_obj)},
     {MP_ROM_QSTR(MP_QSTR_unit_btconly),
      MP_ROM_PTR(&mod_trezorutils_unit_btconly_obj)},
+    {MP_ROM_QSTR(MP_QSTR_sd_hotswap_enabled),
+     MP_ROM_PTR(&mod_trezorutils_sd_hotswap_enabled_obj)},
     // various built-in constants
     {MP_ROM_QSTR(MP_QSTR_SCM_REVISION),
      MP_ROM_PTR(&mod_trezorutils_revision_obj)},

core/embed/lib/unit_variant.c

@@ -1,23 +1,61 @@
-#include "unit_variant.h"
+#include <string.h>
+
 #include "flash_otp.h"
 #include "model.h"
+#include "unit_variant.h"
+#include TREZOR_BOARD
 
 static uint8_t unit_variant_color = 0;
 static bool unit_variant_btconly = false;
 static bool unit_variant_ok = false;
 
+static int16_t unit_variant_build_year = -1;
+
 static void unit_variant_0x01(const uint8_t *data) {
   unit_variant_color = data[1];
   unit_variant_btconly = data[2] == 1;
   unit_variant_ok = true;
 }
 
+static int16_t unit_variant_get_build_year(void) {
+  uint8_t data[FLASH_OTP_BLOCK_SIZE] = {0};
+
+  secbool result =
+      flash_otp_read(FLASH_OTP_BLOCK_BATCH, 0, data, FLASH_OTP_BLOCK_SIZE);
+
+  if (sectrue != result || data[0] == 0xFF) {
+    return -1;
+  }
+
+  /**
+   * Expecting format {MODEL_IDENTIFIER}-YYMMDD
+   *
+   * See also
+   * https://docs.trezor.io/trezor-firmware/core/misc/memory.html?highlight=otp#otp
+   */
+
+  size_t len = strnlen((char *)data, FLASH_OTP_BLOCK_SIZE);
+
+  for (int i = 0; i < len; i++) {
+    if (data[i] == '-') {
+      if ((len - (i + 1)) != 6) {
+        return -1;
+      }
+      return ((int16_t)data[i + 1] - (int16_t)'0') * 10 +
+             ((int16_t)data[i + 2] - (int16_t)'0');
+    }
+  }
+  return -1;
+}
+
 void unit_variant_init(void) {
   uint8_t data[FLASH_OTP_BLOCK_SIZE];
 
   secbool result = flash_otp_read(FLASH_OTP_BLOCK_DEVICE_VARIANT, 0, data,
                                   FLASH_OTP_BLOCK_SIZE);
 
+  unit_variant_build_year = unit_variant_get_build_year();
+
   if (sectrue == result) {
     switch (data[0]) {
       case 0x01:
@@ -34,3 +72,20 @@ uint8_t unit_variant_get_color(void) { return unit_variant_color; }
 bool unit_variant_get_btconly(void) { return unit_variant_btconly; }
 
 bool unit_variant_present(void) { return unit_variant_ok; }
+
+bool unit_variant_is_sd_hotswap_enabled(void) {
+#ifndef USE_SD_CARD
+  return false;
+#else
+#ifdef TREZOR_MODEL_T
+  // early produced TTs have a HW bug that prevents hotswapping of the SD card,
+  // lets check the build data and decide based on that
+  if (unit_variant_build_year <= 18) {
+    return false;
+  }
+  return true;
+#else
+  return true;
+#endif
+#endif
+}

core/embed/lib/unit_variant.h

@@ -9,4 +9,6 @@ bool unit_variant_present(void);
 uint8_t unit_variant_get_color(void);
 bool unit_variant_get_btconly(void);
 
+bool unit_variant_is_sd_hotswap_enabled(void);
+
 #endif  //_UNIT_VARIANT_H

core/embed/prodtest/main.c

@@ -619,7 +619,7 @@ int main(void) {
   draw_welcome_screen();
 
   char dom[32];
-  // format: TREZOR2-YYMMDD
+  // format: {MODEL_IDENTIFIER}-YYMMDD
   if (sectrue == flash_otp_read(FLASH_OTP_BLOCK_BATCH, 0, (uint8_t *)dom, 32) &&
       sectrue == startswith(dom, MODEL_IDENTIFIER) && dom[31] == 0) {
     display_qrcode(DISPLAY_RESX / 2, DISPLAY_RESY / 2, dom, 4);

core/mocks/generated/trezorutils.pyi

@@ -74,6 +74,13 @@ def unit_btconly() -> bool | None:
     """
 
 
+# extmod/modtrezorutils/modtrezorutils.c
+def sd_hotswap_enabled() -> bool:
+    """
+    Returns True if SD card hot swapping is enabled
+    """
+
+
 # extmod/modtrezorutils/modtrezorutils.c
 def reboot_to_bootloader(
     boot_command : int = 0,

core/src/apps/common/sdcard.py

@@ -1,6 +1,6 @@
-from storage.sd_salt import SD_CARD_HOT_SWAPPABLE
 from trezor import TR, io, wire
 from trezor.ui.layouts import confirm_action, show_error_and_raise
+from trezor.utils import sd_hotswap_enabled
 
 
 class SdCardUnavailable(wire.ProcessError):
@@ -8,7 +8,7 @@ class SdCardUnavailable(wire.ProcessError):
 
 
 async def _confirm_retry_wrong_card() -> None:
-    if SD_CARD_HOT_SWAPPABLE:
+    if sd_hotswap_enabled():
         await confirm_action(
             "warning_wrong_sd",
             TR.sd_card__title,
@@ -28,7 +28,7 @@ async def _confirm_retry_wrong_card() -> None:
 
 
 async def _confirm_retry_insert_card() -> None:
-    if SD_CARD_HOT_SWAPPABLE:
+    if sd_hotswap_enabled():
         await confirm_action(
             "warning_no_sd",
             TR.sd_card__title,

core/src/storage/sd_salt.py

@@ -13,7 +13,6 @@ if TYPE_CHECKING:
 if utils.USE_SD_CARD:
     fatfs = io.fatfs  # global_import_cache
 
-SD_CARD_HOT_SWAPPABLE = False
 SD_SALT_LEN_BYTES = const(32)
 _SD_SALT_AUTH_TAG_LEN_BYTES = const(16)
 

core/src/trezor/utils.py

@@ -20,6 +20,7 @@ from trezorutils import (  # noqa: F401
     halt,
     memcpy,
     reboot_to_bootloader,
+    sd_hotswap_enabled,
     unit_btconly,
     unit_color,
 )

docs/core/misc/memory.md

@@ -33,7 +33,7 @@
 
 | block    | range                   | size | function
 |----------|-------------------------|------|--------------------------------
-| block  0 | 0x1FFF7800 - 0x1FFF781F | 32 B | device batch (week of manufacture)
+| block  0 | 0x1FFF7800 - 0x1FFF781F | 32 B | device batch: {MODEL_IDENTIFIER}-YYMMDD
 | block  1 | 0x1FFF7820 - 0x1FFF783F | 32 B | bootloader downgrade protection
 | block  2 | 0x1FFF7840 - 0x1FFF785F | 32 B | vendor keys lock
 | block  3 | 0x1FFF7860 - 0x1FFF787F | 32 B | entropy/randomness