29 files changed, 299 insertions, 75 deletions

diff --git a/tmk_core/avr.mk b/tmk_core/avr.mk
index 690154535..d942e7ade 100644
--- a/tmk_core/avr.mk
+++ b/tmk_core/avr.mk
@@ -237,6 +237,15 @@ endef
 bootloadHID: $(BUILD_DIR)/$(TARGET).hex check-size cpfirmware
         $(call EXEC_BOOTLOADHID)
 
+HID_BOOTLOADER_CLI ?= hid_bootloader_cli
+
+define EXEC_HID_LUFA
+        $(HID_BOOTLOADER_CLI) -mmcu=$(MCU) -w -v $(BUILD_DIR)/$(TARGET).hex
+endef
+
+hid_bootloader: $(BUILD_DIR)/$(TARGET).hex check-size cpfirmware
+        $(call EXEC_HID_LUFA)
+
 # Convert hex to bin.
 bin: $(BUILD_DIR)/$(TARGET).hex
         $(OBJCOPY) -Iihex -Obinary $(BUILD_DIR)/$(TARGET).hex $(BUILD_DIR)/$(TARGET).bin
@@ -295,19 +304,26 @@ extcoff: $(BUILD_DIR)/$(TARGET).elf
         @$(SECHO) $(MSG_EXTENDED_COFF) $(BUILD_DIR)/$(TARGET).cof
         $(COFFCONVERT) -O coff-ext-avr $< $(BUILD_DIR)/$(TARGET).cof
 
-bootloader:
-ifneq ($(strip $(BOOTLOADER)), qmk-dfu)
-        $(error Please set BOOTLOADER = qmk-dfu first!)
+ifeq ($(strip $(BOOTLOADER)), qmk-dfu)
+QMK_BOOTLOADER_TYPE = DFU
+else ifeq ($(strip $(BOOTLOADER)), qmk-hid)
+QMK_BOOTLOADER_TYPE = HID
 endif
-        make -C lib/lufa/Bootloaders/DFU/ clean
-        $(QMK_BIN) generate-dfu-header --quiet --keyboard $(KEYBOARD) --output lib/lufa/Bootloaders/DFU/Keyboard.h
-        $(eval MAX_SIZE=$(shell n=`$(CC) -E -mmcu=$(MCU) $(CFLAGS) $(OPT_DEFS) tmk_core/common/avr/bootloader_size.c 2> /dev/null | sed -ne 's/\r//;/^#/n;/^AVR_SIZE:/,$${s/^AVR_SIZE: //;p;}'` && echo $$(($$n)) || echo 0))
+
+bootloader:
+ifeq ($(strip $(QMK_BOOTLOADER_TYPE)),)
+        $(error Please set BOOTLOADER to "qmk-dfu" or "qmk-hid" first!)
+else
+        make -C lib/lufa/Bootloaders/$(QMK_BOOTLOADER_TYPE)/ clean
+        $(QMK_BIN) generate-dfu-header --quiet --keyboard $(KEYBOARD) --output lib/lufa/Bootloaders/$(QMK_BOOTLOADER_TYPE)/Keyboard.h
+        $(eval MAX_SIZE=$(shell n=`$(CC) -E -mmcu=$(MCU) -D__ASSEMBLER__ $(CFLAGS) $(OPT_DEFS) tmk_core/common/avr/bootloader_size.c 2> /dev/null | sed -ne 's/\r//;/^#/n;/^AVR_SIZE:/,$${s/^AVR_SIZE: //;p;}'` && echo $$(($$n)) || echo 0))
         $(eval PROGRAM_SIZE_KB=$(shell n=`expr $(MAX_SIZE) / 1024` && echo $$(($$n)) || echo 0))
         $(eval BOOT_SECTION_SIZE_KB=$(shell n=`expr  $(BOOTLOADER_SIZE) / 1024` && echo $$(($$n)) || echo 0))
         $(eval FLASH_SIZE_KB=$(shell n=`expr $(PROGRAM_SIZE_KB) + $(BOOT_SECTION_SIZE_KB)` && echo $$(($$n)) || echo 0))
-        make -C lib/lufa/Bootloaders/DFU/ MCU=$(MCU) ARCH=$(ARCH) F_CPU=$(F_CPU) FLASH_SIZE_KB=$(FLASH_SIZE_KB) BOOT_SECTION_SIZE_KB=$(BOOT_SECTION_SIZE_KB)
-        printf "BootloaderDFU.hex copied to $(TARGET)_bootloader.hex\n"
-        cp lib/lufa/Bootloaders/DFU/BootloaderDFU.hex $(TARGET)_bootloader.hex
+        make -C lib/lufa/Bootloaders/$(QMK_BOOTLOADER_TYPE)/ MCU=$(MCU) ARCH=$(ARCH) F_CPU=$(F_CPU) FLASH_SIZE_KB=$(FLASH_SIZE_KB) BOOT_SECTION_SIZE_KB=$(BOOT_SECTION_SIZE_KB)
+        printf "Bootloader$(QMK_BOOTLOADER_TYPE).hex copied to $(TARGET)_bootloader.hex\n"
+        cp lib/lufa/Bootloaders/$(QMK_BOOTLOADER_TYPE)/Bootloader$(QMK_BOOTLOADER_TYPE).hex $(TARGET)_bootloader.hex
+endif
 
 production: $(BUILD_DIR)/$(TARGET).hex bootloader cpfirmware
         @cat $(BUILD_DIR)/$(TARGET).hex | awk '/^:00000001FF/ == 0' > $(TARGET)_production.hex
@@ -328,6 +344,8 @@ else ifeq ($(strip $(BOOTLOADER)), USBasp)
         $(call EXEC_USBASP)
 else ifeq ($(strip $(BOOTLOADER)), bootloadHID)
         $(call EXEC_BOOTLOADHID)
+else ifeq ($(strip $(BOOTLOADER)), qmk-hid)
+        $(call EXEC_HID_LUFA)
 else
         $(PRINT_OK); $(SILENT) || printf "$(MSG_FLASH_BOOTLOADER)"
 endif
diff --git a/tmk_core/chibios.mk b/tmk_core/chibios.mk
index 97299b7d3..7eda36046 100644
--- a/tmk_core/chibios.mk
+++ b/tmk_core/chibios.mk
@@ -390,8 +390,10 @@ ifndef TEENSY_LOADER_CLI
     endif
 endif
 
+TEENSY_LOADER_CLI_MCU ?= $(MCU_LDSCRIPT)
+
 define EXEC_TEENSY
-        $(TEENSY_LOADER_CLI) -mmcu=$(MCU_LDSCRIPT) -w -v $(BUILD_DIR)/$(TARGET).hex
+        $(TEENSY_LOADER_CLI) -mmcu=$(TEENSY_LOADER_CLI_MCU) -w -v $(BUILD_DIR)/$(TARGET).hex
 endef
 
 teensy: $(BUILD_DIR)/$(TARGET).hex cpfirmware sizeafter
@@ -408,6 +410,8 @@ else ifeq ($(strip $(BOOTLOADER)),kiibohd)
         $(call EXEC_DFU_UTIL)
 else ifeq ($(strip $(MCU_FAMILY)),KINETIS)
         $(call EXEC_TEENSY)
+else ifeq ($(strip $(MCU_FAMILY)),MIMXRT1062)
+        $(call EXEC_TEENSY)
 else ifeq ($(strip $(MCU_FAMILY)),STM32)
         $(call EXEC_DFU_UTIL)
 else
diff --git a/tmk_core/common/action_layer.c b/tmk_core/common/action_layer.c
index af2d7d964..ed1a4bd20 100644
--- a/tmk_core/common/action_layer.c
+++ b/tmk_core/common/action_layer.c
@@ -131,32 +131,32 @@ bool layer_state_cmp(layer_state_t cmp_layer_state, uint8_t layer) {
     if (!cmp_layer_state) {
         return layer == 0;
     }
-    return (cmp_layer_state & (1UL << layer)) != 0;
+    return (cmp_layer_state & ((layer_state_t)1 << layer)) != 0;
 }
 
 /** \brief Layer move
  *
  * Turns on the given layer and turn off all other layers
  */
-void layer_move(uint8_t layer) { layer_state_set(1UL << layer); }
+void layer_move(uint8_t layer) { layer_state_set((layer_state_t)1 << layer); }
 
 /** \brief Layer on
  *
  * Turns on given layer
  */
-void layer_on(uint8_t layer) { layer_state_set(layer_state | (1UL << layer)); }
+void layer_on(uint8_t layer) { layer_state_set(layer_state | ((layer_state_t)1 << layer)); }
 
 /** \brief Layer off
  *
  * Turns off given layer
  */
-void layer_off(uint8_t layer) { layer_state_set(layer_state & ~(1UL << layer)); }
+void layer_off(uint8_t layer) { layer_state_set(layer_state & ~((layer_state_t)1 << layer)); }
 
 /** \brief Layer invert
  *
  * Toggle the given layer (set it if it's unset, or unset it if it's set)
  */
-void layer_invert(uint8_t layer) { layer_state_set(layer_state ^ (1UL << layer)); }
+void layer_invert(uint8_t layer) { layer_state_set(layer_state ^ ((layer_state_t)1 << layer)); }
 
 /** \brief Layer or
  *
@@ -258,7 +258,7 @@ uint8_t layer_switch_get_layer(keypos_t key) {
     layer_state_t layers = layer_state | default_layer_state;
     /* check top layer first */
     for (int8_t i = MAX_LAYER - 1; i >= 0; i--) {
-        if (layers & (1UL << i)) {
+        if (layers & ((layer_state_t)1 << i)) {
             action = action_for_key(i, key);
             if (action.code != ACTION_TRANSPARENT) {
                 return i;
diff --git a/tmk_core/common/action_layer.h b/tmk_core/common/action_layer.h
index d72cd3e3a..b87d096ee 100644
--- a/tmk_core/common/action_layer.h
+++ b/tmk_core/common/action_layer.h
@@ -21,6 +21,29 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 #include "keyboard.h"
 #include "action.h"
 
+#ifdef DYNAMIC_KEYMAP_ENABLE
+#    ifndef DYNAMIC_KEYMAP_LAYER_COUNT
+#        define DYNAMIC_KEYMAP_LAYER_COUNT 4
+#    endif
+#    if DYNAMIC_KEYMAP_LAYER_COUNT <= 8
+#        ifndef LAYER_STATE_8BIT
+#            define LAYER_STATE_8BIT
+#        endif
+#    elif DYNAMIC_KEYMAP_LAYER_COUNT <= 16
+#        ifndef LAYER_STATE_16BIT
+#            define LAYER_STATE_16BIT
+#        endif
+#    else
+#        ifndef LAYER_STATE_32BIT
+#            define LAYER_STATE_32BIT
+#        endif
+#    endif
+#endif
+
+#if !defined(LAYER_STATE_8BIT) && !defined(LAYER_STATE_16BIT) && !defined(LAYER_STATE_32BIT)
+#    define LAYER_STATE_32BIT
+#endif
+
 #if defined(LAYER_STATE_8BIT)
 typedef uint8_t layer_state_t;
 #    define MAX_LAYER_BITS 3
@@ -35,13 +58,15 @@ typedef uint16_t layer_state_t;
 #        define MAX_LAYER 16
 #    endif
 #    define get_highest_layer(state) biton16(state)
-#else
+#elif defined(LAYER_STATE_32BIT)
 typedef uint32_t layer_state_t;
 #    define MAX_LAYER_BITS 5
 #    ifndef MAX_LAYER
 #        define MAX_LAYER 32
 #    endif
 #    define get_highest_layer(state) biton32(state)
+#else
+#    error Layer Mask size not specified.  HOW?!
 #endif
 
 /*
@@ -92,7 +117,7 @@ layer_state_t layer_state_set_kb(layer_state_t state);
 
 #    define layer_state_set(layer)
 #    define layer_state_is(layer) (layer == 0)
-#    define layer_state_cmp(state, layer) (state == 0 ? layer == 0 : (state & 1UL << layer) != 0)
+#    define layer_state_cmp(state, layer) (state == 0 ? layer == 0 : (state & (layer_state_t)1 << layer) != 0)
 
 #    define layer_debug()
 #    define layer_clear()
diff --git a/tmk_core/common/action_util.c b/tmk_core/common/action_util.c
index a57c8bf66..2b3c00cba 100644
--- a/tmk_core/common/action_util.c
+++ b/tmk_core/common/action_util.c
@@ -27,6 +27,10 @@ extern keymap_config_t keymap_config;
 static uint8_t real_mods  = 0;
 static uint8_t weak_mods  = 0;
 static uint8_t macro_mods = 0;
+#ifdef KEY_OVERRIDE_ENABLE
+static uint8_t weak_override_mods = 0;
+static uint8_t suppressed_mods    = 0;
+#endif
 
 #ifdef USB_6KRO_ENABLE
 #    define RO_ADD(a, b) ((a + b) % KEYBOARD_REPORT_KEYS)
@@ -229,6 +233,7 @@ void send_keyboard_report(void) {
     keyboard_report->mods = real_mods;
     keyboard_report->mods |= weak_mods;
     keyboard_report->mods |= macro_mods;
+
 #ifndef NO_ACTION_ONESHOT
     if (oneshot_mods) {
 #    if (defined(ONESHOT_TIMEOUT) && (ONESHOT_TIMEOUT > 0))
@@ -244,6 +249,13 @@ void send_keyboard_report(void) {
     }
 
 #endif
+
+#ifdef KEY_OVERRIDE_ENABLE
+    // These need to be last to be able to properly control key overrides
+    keyboard_report->mods &= ~suppressed_mods;
+    keyboard_report->mods |= weak_override_mods;
+#endif
+
     host_keyboard_send(keyboard_report);
 }
 
@@ -299,6 +311,22 @@ void set_weak_mods(uint8_t mods) { weak_mods = mods; }
  */
 void clear_weak_mods(void) { weak_mods = 0; }
 
+#ifdef KEY_OVERRIDE_ENABLE
+/** \brief set weak mods used by key overrides. DO not call this manually
+ */
+void set_weak_override_mods(uint8_t mods) { weak_override_mods = mods; }
+/** \brief clear weak mods used by key overrides. DO not call this manually
+ */
+void clear_weak_override_mods(void) { weak_override_mods = 0; }
+
+/** \brief set suppressed mods used by key overrides. DO not call this manually
+ */
+void set_suppressed_override_mods(uint8_t mods) { suppressed_mods = mods; }
+/** \brief clear suppressed mods used by key overrides. DO not call this manually
+ */
+void clear_suppressed_override_mods(void) { suppressed_mods = 0; }
+#endif
+
 /* macro modifier */
 /** \brief get macro mods
  *
diff --git a/tmk_core/common/arm_atsam/_timer.h b/tmk_core/common/arm_atsam/_timer.h
new file mode 100644
index 000000000..77402b612
--- /dev/null
+++ b/tmk_core/common/arm_atsam/_timer.h
@@ -0,0 +1,19 @@
+/* Copyright 2021 Simon Arlott
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+#pragma once
+
+// The platform is 32-bit, so prefer 32-bit timers to avoid overflow
+#define FAST_TIMER_T_SIZE 32
diff --git a/tmk_core/common/avr/_timer.h b/tmk_core/common/avr/_timer.h
new file mode 100644
index 000000000..b81e0f68b
--- /dev/null
+++ b/tmk_core/common/avr/_timer.h
@@ -0,0 +1,19 @@
+/* Copyright 2021 Simon Arlott
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+#pragma once
+
+// The platform is 8-bit, so prefer 16-bit timers to reduce code size
+#define FAST_TIMER_T_SIZE 16
diff --git a/tmk_core/common/avr/gpio.h b/tmk_core/common/avr/gpio.h
index 231556c29..e9be68491 100644
--- a/tmk_core/common/avr/gpio.h
+++ b/tmk_core/common/avr/gpio.h
@@ -20,6 +20,8 @@
 
 typedef uint8_t pin_t;
 
+/* Operation of GPIO by pin. */
+
 #define setPinInput(pin) (DDRx_ADDRESS(pin) &= ~_BV((pin)&0xF), PORTx_ADDRESS(pin) &= ~_BV((pin)&0xF))
 #define setPinInputHigh(pin) (DDRx_ADDRESS(pin) &= ~_BV((pin)&0xF), PORTx_ADDRESS(pin) |= _BV((pin)&0xF))
 #define setPinInputLow(pin) _Static_assert(0, "AVR processors cannot implement an input as pull low")
@@ -32,3 +34,16 @@ typedef uint8_t pin_t;
 #define readPin(pin) ((bool)(PINx_ADDRESS(pin) & _BV((pin)&0xF)))
 
 #define togglePin(pin) (PORTx_ADDRESS(pin) ^= _BV((pin)&0xF))
+
+/* Operation of GPIO by port. */
+
+typedef uint8_t port_data_t;
+
+#define readPort(port) PINx_ADDRESS(port)
+
+#define setPortBitInput(port, bit) (DDRx_ADDRESS(port) &= ~_BV((bit)&0xF), PORTx_ADDRESS(port) &= ~_BV((bit)&0xF))
+#define setPortBitInputHigh(port, bit) (DDRx_ADDRESS(port) &= ~_BV((bit)&0xF), PORTx_ADDRESS(port) |= _BV((bit)&0xF))
+#define setPortBitOutput(port, bit) (DDRx_ADDRESS(port) |= _BV((bit)&0xF))
+
+#define writePortBitLow(port, bit) (PORTx_ADDRESS(port) &= ~_BV((bit)&0xF))
+#define writePortBitHigh(port, bit) (PORTx_ADDRESS(port) |= _BV((bit)&0xF))
diff --git a/tmk_core/common/chibios/_timer.h b/tmk_core/common/chibios/_timer.h
new file mode 100644
index 000000000..77402b612
--- /dev/null
+++ b/tmk_core/common/chibios/_timer.h
@@ -0,0 +1,19 @@
+/* Copyright 2021 Simon Arlott
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+#pragma once
+
+// The platform is 32-bit, so prefer 32-bit timers to avoid overflow
+#define FAST_TIMER_T_SIZE 32
diff --git a/tmk_core/common/chibios/bootloader.c b/tmk_core/common/chibios/bootloader.c
index 11f7abf43..f9514ee5f 100644
--- a/tmk_core/common/chibios/bootloader.c
+++ b/tmk_core/common/chibios/bootloader.c
@@ -95,7 +95,7 @@ void enter_bootloader_mode_if_requested(void) {
     }
 }
 
-#elif defined(KL2x) || defined(K20x) || defined(MK66F18)  // STM32_BOOTLOADER_DUAL_BANK // STM32_BOOTLOADER_ADDRESS
+#elif defined(KL2x) || defined(K20x) || defined(MK66F18) || defined(MIMXRT1062)  // STM32_BOOTLOADER_DUAL_BANK // STM32_BOOTLOADER_ADDRESS
 /* Kinetis */
 
 #    if defined(BOOTLOADER_KIIBOHD)
@@ -103,7 +103,8 @@ void enter_bootloader_mode_if_requested(void) {
 #        define SCB_AIRCR_VECTKEY_WRITEMAGIC 0x05FA0000
 const uint8_t              sys_reset_to_loader_magic[] = "\xff\x00\x7fRESET TO LOADER\x7f\x00\xff";
 __attribute__((weak)) void bootloader_jump(void) {
-    __builtin_memcpy((void *)VBAT, (const void *)sys_reset_to_loader_magic, sizeof(sys_reset_to_loader_magic));
+    void *volatile vbat = (void *)VBAT;
+    __builtin_memcpy(vbat, (const void *)sys_reset_to_loader_magic, sizeof(sys_reset_to_loader_magic));
     // request reset
     SCB->AIRCR = SCB_AIRCR_VECTKEY_WRITEMAGIC | SCB_AIRCR_SYSRESETREQ_Msk;
 }
diff --git a/tmk_core/common/chibios/gpio.h b/tmk_core/common/chibios/gpio.h
index 5d0e142ab..4d057f1ca 100644
--- a/tmk_core/common/chibios/gpio.h
+++ b/tmk_core/common/chibios/gpio.h
@@ -20,6 +20,8 @@
 
 typedef ioline_t pin_t;
 
+/* Operation of GPIO by pin. */
+
 #define setPinInput(pin) palSetLineMode(pin, PAL_MODE_INPUT)
 #define setPinInputHigh(pin) palSetLineMode(pin, PAL_MODE_INPUT_PULLUP)
 #define setPinInputLow(pin) palSetLineMode(pin, PAL_MODE_INPUT_PULLDOWN)
@@ -32,3 +34,17 @@ typedef ioline_t pin_t;
 #define readPin(pin) palReadLine(pin)
 
 #define togglePin(pin) palToggleLine(pin)
+
+/* Operation of GPIO by port. */
+
+typedef uint16_t port_data_t;
+
+#define readPort(pin) palReadPort(PAL_PORT(pin))
+
+#define setPortBitInput(pin, bit) palSetPadMode(PAL_PORT(pin), bit, PAL_MODE_INPUT)
+#define setPortBitInputHigh(pin, bit) palSetPadMode(PAL_PORT(pin), bit, PAL_MODE_INPUT_PULLUP)
+#define setPortBitInputLow(pin, bit) palSetPadMode(PAL_PORT(pin), bit, PAL_MODE_INPUT_PULLDOWN)
+#define setPortBitOutput(pin, bit) palSetPadMode(PAL_PORT(pin), bit, PAL_MODE_OUTPUT_PUSHPULL)
+
+#define writePortBitLow(pin, bit) palClearLine(PAL_LINE(PAL_PORT(pin), bit))
+#define writePortBitHigh(pin, bit) palSetLine(PAL_LINE(PAL_PORT(pin), bit))
diff --git a/tmk_core/common/host.c b/tmk_core/common/host.c
index e7d92cfac..a8b391e89 100644
--- a/tmk_core/common/host.c
+++ b/tmk_core/common/host.c
@@ -17,6 +17,7 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
 #include <stdint.h>
 //#include <avr/interrupt.h>
+#include "keyboard.h"
 #include "keycode.h"
 #include "host.h"
 #include "util.h"
@@ -35,15 +36,20 @@ void host_set_driver(host_driver_t *d) { driver = d; }
 
 host_driver_t *host_get_driver(void) { return driver; }
 
+#ifdef SPLIT_KEYBOARD
+uint8_t split_led_state = 0;
+void    set_split_host_keyboard_leds(uint8_t led_state) { split_led_state = led_state; }
+#endif
+
 uint8_t host_keyboard_leds(void) {
+#ifdef SPLIT_KEYBOARD
+    if (!is_keyboard_master()) return split_led_state;
+#endif
     if (!driver) return 0;
     return (*driver->keyboard_leds)();
 }
 
-led_t host_keyboard_led_state(void) {
-    if (!driver) return (led_t){0};
-    return (led_t)((*driver->keyboard_leds)());
-}
+led_t host_keyboard_led_state(void) { return (led_t)host_keyboard_leds(); }
 
 /* send report */
 void host_keyboard_send(report_keyboard_t *report) {
diff --git a/tmk_core/common/keyboard.c b/tmk_core/common/keyboard.c
index 3d6092e71..28fa97bc8 100644
--- a/tmk_core/common/keyboard.c
+++ b/tmk_core/common/keyboard.c
@@ -85,6 +85,9 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 #ifdef OLED_DRIVER_ENABLE
 #    include "oled_driver.h"
 #endif
+#ifdef ST7565_ENABLE
+#    include "st7565.h"
+#endif
 #ifdef VELOCIKEY_ENABLE
 #    include "velocikey.h"
 #endif
@@ -100,6 +103,9 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 #ifdef EEPROM_DRIVER
 #    include "eeprom_driver.h"
 #endif
+#if defined(CRC_ENABLE)
+#    include "crc.h"
+#endif
 
 static uint32_t last_input_modification_time = 0;
 uint32_t        last_input_activity_time(void) { return last_input_modification_time; }
@@ -297,6 +303,9 @@ void keyboard_init(void) {
     timer_init();
     sync_timer_init();
     matrix_init();
+#if defined(CRC_ENABLE)
+    crc_init();
+#endif
 #ifdef VIA_ENABLE
     via_init();
 #endif
@@ -306,6 +315,9 @@ void keyboard_init(void) {
 #ifdef OLED_DRIVER_ENABLE
     oled_init(OLED_ROTATION_0);
 #endif
+#ifdef ST7565_ENABLE
+    st7565_init(DISPLAY_ROTATION_0);
+#endif
 #ifdef PS2_MOUSE_ENABLE
     ps2_mouse_init();
 #endif
@@ -470,6 +482,18 @@ MATRIX_LOOP_END:
 #    endif
 #endif
 
+#ifdef ST7565_ENABLE
+    st7565_task();
+#    ifndef ST7565_DISABLE_TIMEOUT
+    // Wake up display if user is using those fabulous keys or spinning those encoders!
+#        ifdef ENCODER_ENABLE
+    if (matrix_changed || encoders_changed) st7565_on();
+#        else
+    if (matrix_changed) st7565_on();
+#        endif
+#    endif
+#endif
+
 #ifdef MOUSEKEY_ENABLE
     // mousekey repeat & acceleration
     mousekey_task();
diff --git a/tmk_core/common/progmem.h b/tmk_core/common/progmem.h
index 4e4771e52..3a7a16968 100644
--- a/tmk_core/common/progmem.h
+++ b/tmk_core/common/progmem.h
@@ -3,6 +3,7 @@
 #if defined(__AVR__)
 #    include <avr/pgmspace.h>
 #else
+#    include <string.h>
 #    define PROGMEM
 #    define PSTR(x) x
 #    define PGM_P const char*
diff --git a/tmk_core/common/sync_timer.c b/tmk_core/common/sync_timer.c
index de24b463b..68b92d8b4 100644
--- a/tmk_core/common/sync_timer.c
+++ b/tmk_core/common/sync_timer.c
@@ -26,7 +26,7 @@ SOFTWARE.
 #include "sync_timer.h"
 #include "keyboard.h"
 
-#if defined(SPLIT_KEYBOARD) && !defined(DISABLE_SYNC_TIMER)
+#if (defined(SPLIT_KEYBOARD) || defined(SERIAL_LINK_ENABLE)) && !defined(DISABLE_SYNC_TIMER)
 volatile int32_t sync_timer_ms;
 
 void sync_timer_init(void) { sync_timer_ms = 0; }
diff --git a/tmk_core/common/sync_timer.h b/tmk_core/common/sync_timer.h
index 9ddef45bb..744e2b50d 100644
--- a/tmk_core/common/sync_timer.h
+++ b/tmk_core/common/sync_timer.h
@@ -32,7 +32,7 @@ SOFTWARE.
 extern "C" {
 #endif
 
-#if defined(SPLIT_KEYBOARD) && !defined(DISABLE_SYNC_TIMER)
+#if (defined(SPLIT_KEYBOARD) || defined(SERIAL_LINK_ENABLE)) && !defined(DISABLE_SYNC_TIMER)
 void     sync_timer_init(void);
 void     sync_timer_update(uint32_t time);
 uint16_t sync_timer_read(void);
diff --git a/tmk_core/common/timer.h b/tmk_core/common/timer.h
index abddcea85..02e39e79e 100644
--- a/tmk_core/common/timer.h
+++ b/tmk_core/common/timer.h
@@ -1,5 +1,6 @@
 /*
 Copyright 2011 Jun Wako <wakojun@gmail.com>
+Copyright 2021 Simon Arlott
 
 This program is free software: you can redistribute it and/or modify
 it under the terms of the GNU General Public License as published by
@@ -17,6 +18,10 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
 #pragma once
 
+#if __has_include_next("_timer.h")
+#    include_next "_timer.h" /* Include the platform's _timer.h */
+#endif
+
 #include <stdint.h>
 
 #define TIMER_DIFF(a, b, max) ((max == UINT8_MAX) ? ((uint8_t)((a) - (b))) : ((max == UINT16_MAX) ? ((uint16_t)((a) - (b))) : ((max == UINT32_MAX) ? ((uint32_t)((a) - (b))) : ((a) >= (b) ? (a) - (b) : (max) + 1 - (b) + (a)))))
@@ -42,6 +47,21 @@ uint32_t timer_elapsed32(uint32_t last);
 #define timer_expired(current, future) ((uint16_t)(current - future) < UINT16_MAX / 2)
 #define timer_expired32(current, future) ((uint32_t)(current - future) < UINT32_MAX / 2)
 
+// Use an appropriate timer integer size based on architecture (16-bit will overflow sooner)
+#if FAST_TIMER_T_SIZE < 32
+#    define TIMER_DIFF_FAST(a, b) TIMER_DIFF_16(a, b)
+#    define timer_expired_fast(current, future) timer_expired(current, future)
+typedef uint16_t fast_timer_t;
+fast_timer_t inline timer_read_fast(void) { return timer_read(); }
+fast_timer_t inline timer_elapsed_fast(fast_timer_t last) { return timer_elapsed(last); }
+#else
+#    define TIMER_DIFF_FAST(a, b) TIMER_DIFF_32(a, b)
+#    define timer_expired_fast(current, future) timer_expired32(current, future)
+typedef uint32_t fast_timer_t;
+fast_timer_t inline timer_read_fast(void) { return timer_read32(); }
+fast_timer_t inline timer_elapsed_fast(fast_timer_t last) { return timer_elapsed32(last); }
+#endif
+
 #ifdef __cplusplus
 }
 #endif
diff --git a/tmk_core/common/usb_util.c b/tmk_core/common/usb_util.c
index d4134a044..dd1deeaa1 100644
--- a/tmk_core/common/usb_util.c
+++ b/tmk_core/common/usb_util.c
@@ -16,7 +16,7 @@
 #include "quantum.h"
 #include "usb_util.h"
 
-__attribute__((weak)) void usb_disable(void) {}
+__attribute__((weak)) void usb_disconnect(void) {}
 __attribute__((weak)) bool usb_connected_state(void) { return true; }
 __attribute__((weak)) bool usb_vbus_state(void) {
 #ifdef USB_VBUS_PIN
diff --git a/tmk_core/common/usb_util.h b/tmk_core/common/usb_util.h
index 4ebedb1e7..13db9fbfb 100644
--- a/tmk_core/common/usb_util.h
+++ b/tmk_core/common/usb_util.h
@@ -17,6 +17,6 @@
 
 #include <stdbool.h>
 
-void usb_disable(void);
+void usb_disconnect(void);
 bool usb_connected_state(void);
 bool usb_vbus_state(void);
diff --git a/tmk_core/protocol/arm_atsam/usb/udi_device_conf.h b/tmk_core/protocol/arm_atsam/usb/udi_device_conf.h
index 9c9d94789..1c0983115 100644
--- a/tmk_core/protocol/arm_atsam/usb/udi_device_conf.h
+++ b/tmk_core/protocol/arm_atsam/usb/udi_device_conf.h
@@ -23,6 +23,10 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 #include "compiler.h"
 #include "usb_protocol_hid.h"
 
+#ifndef USB_POLLING_INTERVAL_MS
+#    define USB_POLLING_INTERVAL_MS 10
+#endif
+
 #ifdef VIRTSER_ENABLE
 // because CDC uses IAD (interface association descriptor
 // per USB Interface Association Descriptor Device Class Code and Use Model 7/23/2003 Rev 1.0)
@@ -118,7 +122,7 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 #define UDI_HID_KBD_EP_IN KEYBOARD_IN_EPNUM
 #define NEXT_IN_EPNUM_1 (KEYBOARD_IN_EPNUM + 1)
 #define UDI_HID_KBD_EP_SIZE KEYBOARD_EPSIZE
-#define KBD_POLLING_INTERVAL 10
+#define KBD_POLLING_INTERVAL USB_POLLING_INTERVAL_MS
 #ifndef UDI_HID_KBD_STRING_ID
 #    define UDI_HID_KBD_STRING_ID 0
 #endif
@@ -128,7 +132,7 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 #    define NEXT_IN_EPNUM_2 (MOUSE_IN_EPNUM + 1)
 #    define UDI_HID_MOU_EP_IN MOUSE_IN_EPNUM
 #    define UDI_HID_MOU_EP_SIZE MOUSE_EPSIZE
-#    define MOU_POLLING_INTERVAL 10
+#    define MOU_POLLING_INTERVAL USB_POLLING_INTERVAL_MS
 #    ifndef UDI_HID_MOU_STRING_ID
 #        define UDI_HID_MOU_STRING_ID 0
 #    endif
@@ -141,7 +145,7 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 #    define UDI_HID_EXK_EP_IN EXTRAKEY_IN_EPNUM
 #    define NEXT_IN_EPNUM_3 (EXTRAKEY_IN_EPNUM + 1)
 #    define UDI_HID_EXK_EP_SIZE EXTRAKEY_EPSIZE
-#    define EXTRAKEY_POLLING_INTERVAL 10
+#    define EXTRAKEY_POLLING_INTERVAL USB_POLLING_INTERVAL_MS
 #    ifndef UDI_HID_EXK_STRING_ID
 #        define UDI_HID_EXK_STRING_ID 0
 #    endif
diff --git a/tmk_core/protocol/chibios/usb_main.c b/tmk_core/protocol/chibios/usb_main.c
index d04302aca..407b8ea75 100644
--- a/tmk_core/protocol/chibios/usb_main.c
+++ b/tmk_core/protocol/chibios/usb_main.c
@@ -903,7 +903,8 @@ static void send_extra(uint8_t report_id, uint16_t data) {
         return;
     }
 
-    report_extra_t report = {.report_id = report_id, .usage = data};
+    static report_extra_t report;
+    report = (report_extra_t){.report_id = report_id, .usage = data};
 
     usbStartTransmitI(&USB_DRIVER, SHARED_IN_EPNUM, (uint8_t *)&report, sizeof(report_extra_t));
     osalSysUnlock();
@@ -1051,45 +1052,44 @@ void virtser_task(void) {
 #ifdef JOYSTICK_ENABLE
 
 void send_joystick_packet(joystick_t *joystick) {
-    joystick_report_t rep = {
+    static joystick_report_t rep;
+    rep = (joystick_report_t) {
 #    if JOYSTICK_AXES_COUNT > 0
         .axes =
-            {
-                joystick->axes[0],
+        { joystick->axes[0],
 
 #        if JOYSTICK_AXES_COUNT >= 2
-                joystick->axes[1],
+          joystick->axes[1],
 #        endif
 #        if JOYSTICK_AXES_COUNT >= 3
-                joystick->axes[2],
+          joystick->axes[2],
 #        endif
 #        if JOYSTICK_AXES_COUNT >= 4
-                joystick->axes[3],
+          joystick->axes[3],
 #        endif
 #        if JOYSTICK_AXES_COUNT >= 5
-                joystick->axes[4],
+          joystick->axes[4],
 #        endif
 #        if JOYSTICK_AXES_COUNT >= 6
-                joystick->axes[5],
+          joystick->axes[5],
 #        endif
-            },
+        },
 #    endif  // JOYSTICK_AXES_COUNT>0
 
 #    if JOYSTICK_BUTTON_COUNT > 0
-        .buttons =
-            {
-                joystick->buttons[0],
+        .buttons = {
+            joystick->buttons[0],
 
 #        if JOYSTICK_BUTTON_COUNT > 8
-                joystick->buttons[1],
+            joystick->buttons[1],
 #        endif
 #        if JOYSTICK_BUTTON_COUNT > 16
-                joystick->buttons[2],
+            joystick->buttons[2],
 #        endif
 #        if JOYSTICK_BUTTON_COUNT > 24
-                joystick->buttons[3],
+            joystick->buttons[3],
 #        endif
-            }
+        }
 #    endif  // JOYSTICK_BUTTON_COUNT>0
     };
 
diff --git a/tmk_core/protocol/chibios/usb_util.c b/tmk_core/protocol/chibios/usb_util.c
index 5945e8a8d..e32d6ebfa 100644
--- a/tmk_core/protocol/chibios/usb_util.c
+++ b/tmk_core/protocol/chibios/usb_util.c
@@ -16,6 +16,6 @@
 #include <hal.h>
 #include "usb_util.h"
 
-void usb_disable(void) { usbStop(&USBD1); }
+void usb_disconnect(void) { usbStop(&USBD1); }
 
 bool usb_connected_state(void) { return usbGetDriverStateI(&USBD1) == USB_ACTIVE; }
diff --git a/tmk_core/protocol/lufa/lufa.c b/tmk_core/protocol/lufa/lufa.c
index 63619fdb3..4ac079e16 100644
--- a/tmk_core/protocol/lufa/lufa.c
+++ b/tmk_core/protocol/lufa/lufa.c
@@ -314,45 +314,44 @@ static void Console_Task(void) {
 void send_joystick_packet(joystick_t *joystick) {
     uint8_t timeout = 255;
 
-    joystick_report_t r = {
+    static joystick_report_t;
+    r = (joystick_report_t) {
 #    if JOYSTICK_AXES_COUNT > 0
         .axes =
-            {
-                joystick->axes[0],
+        { joystick->axes[0],
 
 #        if JOYSTICK_AXES_COUNT >= 2
-                joystick->axes[1],
+          joystick->axes[1],
 #        endif
 #        if JOYSTICK_AXES_COUNT >= 3
-                joystick->axes[2],
+          joystick->axes[2],
 #        endif
 #        if JOYSTICK_AXES_COUNT >= 4
-                joystick->axes[3],
+          joystick->axes[3],
 #        endif
 #        if JOYSTICK_AXES_COUNT >= 5
-                joystick->axes[4],
+          joystick->axes[4],
 #        endif
 #        if JOYSTICK_AXES_COUNT >= 6
-                joystick->axes[5],
+          joystick->axes[5],
 #        endif
-            },
+        },
 #    endif  // JOYSTICK_AXES_COUNT>0
 
 #    if JOYSTICK_BUTTON_COUNT > 0
-        .buttons =
-            {
-                joystick->buttons[0],
+        .buttons = {
+            joystick->buttons[0],
 
 #        if JOYSTICK_BUTTON_COUNT > 8
-                joystick->buttons[1],
+            joystick->buttons[1],
 #        endif
 #        if JOYSTICK_BUTTON_COUNT > 16
-                joystick->buttons[2],
+            joystick->buttons[2],
 #        endif
 #        if JOYSTICK_BUTTON_COUNT > 24
-                joystick->buttons[3],
+            joystick->buttons[3],
 #        endif
-            }
+        }
 #    endif  // JOYSTICK_BUTTON_COUNT>0
     };
 
@@ -768,7 +767,8 @@ static void send_extra(uint8_t report_id, uint16_t data) {
 
     if (USB_DeviceState != DEVICE_STATE_Configured) return;
 
-    report_extra_t r = {.report_id = report_id, .usage = data};
+    static report_extra_t r;
+    r = (report_extra_t){.report_id = report_id, .usage = data};
     Endpoint_SelectEndpoint(SHARED_IN_EPNUM);
 
     /* Check if write ready for a polling interval around 10ms */
diff --git a/tmk_core/protocol/lufa/usb_util.c b/tmk_core/protocol/lufa/usb_util.c
index 9e943a21b..9691eff1e 100644
--- a/tmk_core/protocol/lufa/usb_util.c
+++ b/tmk_core/protocol/lufa/usb_util.c
@@ -17,7 +17,7 @@
 #include "usb_util.h"
 #include "wait.h"
 
-void usb_disable(void) {
+void usb_disconnect(void) {
     USB_Disable();
     USB_DeviceState = DEVICE_STATE_Unattached;
 }
diff --git a/tmk_core/protocol/usb_descriptor.c b/tmk_core/protocol/usb_descriptor.c
index ba7760f28..7a4a79031 100644
--- a/tmk_core/protocol/usb_descriptor.c
+++ b/tmk_core/protocol/usb_descriptor.c
@@ -351,7 +351,7 @@ const USB_Descriptor_Device_t PROGMEM DeviceDescriptor = {
         .Size                   = sizeof(USB_Descriptor_Device_t),
         .Type                   = DTYPE_Device
     },
-    .USBSpecification           = VERSION_BCD(1, 1, 0),
+    .USBSpecification           = VERSION_BCD(2, 0, 0),
 
 #if VIRTSER_ENABLE
     .Class                      = USB_CSCP_IADDeviceClass,
@@ -953,10 +953,10 @@ const USB_Descriptor_String_t PROGMEM ProductString = {
 #if defined(SERIAL_NUMBER)
 const USB_Descriptor_String_t PROGMEM SerialNumberString = {
     .Header = {
-        .Size                   = USB_STRING_LEN(sizeof(STR(SERIAL_NUMBER)) - 1), // Subtract 1 for null terminator
+        .Size                   = USB_STRING_LEN(sizeof(SERIAL_NUMBER) - 1), // Subtract 1 for null terminator
         .Type                   = DTYPE_String
     },
-    .UnicodeString              = LSTR(SERIAL_NUMBER)
+    .UnicodeString              = USBSTR(SERIAL_NUMBER)
 };
 #endif
 
diff --git a/tmk_core/protocol/usb_descriptor_common.h b/tmk_core/protocol/usb_descriptor_common.h
index b1f602c82..ce0cf0976 100644
--- a/tmk_core/protocol/usb_descriptor_common.h
+++ b/tmk_core/protocol/usb_descriptor_common.h
@@ -16,6 +16,10 @@
 
 #pragma once
 
+// Prefix string literal with L for descriptors
+#define USBCONCAT(a, b) a##b
+#define USBSTR(s) USBCONCAT(L, s)
+
 /////////////////////
 // RAW Usage page and ID configuration
 
diff --git a/tmk_core/protocol/vusb/usb_util.c b/tmk_core/protocol/vusb/usb_util.c
index 602854dbe..4ee2d3188 100644
--- a/tmk_core/protocol/vusb/usb_util.c
+++ b/tmk_core/protocol/vusb/usb_util.c
@@ -16,7 +16,7 @@
 #include <usbdrv/usbdrv.h>
 #include "usb_util.h"
 
-void usb_disable(void) { usbDeviceDisconnect(); }
+void usb_disconnect(void) { usbDeviceDisconnect(); }
 
 bool usb_connected_state(void) {
     usbPoll();
diff --git a/tmk_core/protocol/vusb/vusb.c b/tmk_core/protocol/vusb/vusb.c
index 9362fbde7..98cebf601 100644
--- a/tmk_core/protocol/vusb/vusb.c
+++ b/tmk_core/protocol/vusb/vusb.c
@@ -272,7 +272,8 @@ static void send_extra(uint8_t report_id, uint16_t data) {
     last_id   = report_id;
     last_data = data;
 
-    report_extra_t report = {.report_id = report_id, .usage = data};
+    static report_extra_t report;
+    report = (report_extra_t){.report_id = report_id, .usage = data};
     if (usbInterruptIsReadyShared()) {
         usbSetInterruptShared((void *)&report, sizeof(report_extra_t));
     }
@@ -598,10 +599,10 @@ const PROGMEM usbStringDescriptor_t usbStringDescriptorProduct = {
 #if defined(SERIAL_NUMBER)
 const PROGMEM usbStringDescriptor_t usbStringDescriptorSerial = {
     .header = {
-        .bLength         = USB_STRING_LEN(sizeof(STR(SERIAL_NUMBER)) - 1),
+        .bLength         = USB_STRING_LEN(sizeof(SERIAL_NUMBER) - 1),
         .bDescriptorType = USBDESCR_STRING
     },
-    .bString             = LSTR(SERIAL_NUMBER)
+    .bString             = USBSTR(SERIAL_NUMBER)
 };
 #endif
 
diff --git a/tmk_core/rules.mk b/tmk_core/rules.mk
index fc2dc68be..597f7aa82 100644
--- a/tmk_core/rules.mk
+++ b/tmk_core/rules.mk
@@ -458,7 +458,7 @@ ifeq ($(findstring avr-gcc,$(CC)),avr-gcc)
 SIZE_MARGIN = 1024
 
 check-size:
-        $(eval MAX_SIZE=$(shell n=`$(CC) -E -mmcu=$(MCU) $(CFLAGS) $(OPT_DEFS) tmk_core/common/avr/bootloader_size.c 2> /dev/null | sed -ne 's/\r//;/^#/n;/^AVR_SIZE:/,$${s/^AVR_SIZE: //;p;}'` && echo $$(($$n)) || echo 0))
+        $(eval MAX_SIZE=$(shell n=`$(CC) -E -mmcu=$(MCU) -D__ASSEMBLER__ $(CFLAGS) $(OPT_DEFS) tmk_core/common/avr/bootloader_size.c 2> /dev/null | sed -ne 's/\r//;/^#/n;/^AVR_SIZE:/,$${s/^AVR_SIZE: //;p;}'` && echo $$(($$n)) || echo 0))
         $(eval CURRENT_SIZE=$(shell if [ -f $(BUILD_DIR)/$(TARGET).hex ]; then $(SIZE) --target=$(FORMAT) $(BUILD_DIR)/$(TARGET).hex | $(AWK) 'NR==2 {print $$4}'; else printf 0; fi))
         $(eval FREE_SIZE=$(shell expr $(MAX_SIZE) - $(CURRENT_SIZE)))
         $(eval OVER_SIZE=$(shell expr $(CURRENT_SIZE) - $(MAX_SIZE)))