6 files changed, 176 insertions, 2 deletions

diff --git a/tmk_core/common/chibios/bootloader.c b/tmk_core/common/chibios/bootloader.c
index f9514ee5f..5cadadeee 100644
--- a/tmk_core/common/chibios/bootloader.c
+++ b/tmk_core/common/chibios/bootloader.c
@@ -95,6 +95,28 @@ void enter_bootloader_mode_if_requested(void) {
     }
 }
 
+#elif defined(GD32VF103)
+
+#    define DBGMCU_KEY_UNLOCK 0x4B5A6978
+#    define DBGMCU_CMD_RESET 0x1
+
+__IO uint32_t *DBGMCU_KEY = (uint32_t *)DBGMCU_BASE + 0x0CU;
+__IO uint32_t *DBGMCU_CMD = (uint32_t *)DBGMCU_BASE + 0x08U;
+
+__attribute__((weak)) void bootloader_jump(void) {
+    /* The MTIMER unit of the GD32VF103 doesn't have the MSFRST
+     * register to generate a software reset request.
+     * BUT instead two undocumented registers in the debug peripheral
+     * that allow issueing a software reset. WHO would need the MSFRST
+     * register anyway? Source:
+     * https://github.com/esmil/gd32vf103inator/blob/master/include/gd32vf103/dbg.h */
+    *DBGMCU_KEY = DBGMCU_KEY_UNLOCK;
+    *DBGMCU_CMD = DBGMCU_CMD_RESET;
+}
+
+void enter_bootloader_mode_if_requested(void) { /* Jumping to bootloader is not possible from user code. */
+}
+
 #elif defined(KL2x) || defined(K20x) || defined(MK66F18) || defined(MIMXRT1062)  // STM32_BOOTLOADER_DUAL_BANK // STM32_BOOTLOADER_ADDRESS
 /* Kinetis */
 
diff --git a/tmk_core/common/chibios/chibios_config.h b/tmk_core/common/chibios/chibios_config.h
index f06594802..ad2f808a9 100644
--- a/tmk_core/common/chibios/chibios_config.h
+++ b/tmk_core/common/chibios/chibios_config.h
@@ -39,6 +39,25 @@
 #    endif
 #endif
 
+// GD32 compatibility
+#if defined(MCU_GD32V)
+#    define CPU_CLOCK GD32_SYSCLK
+
+#    if defined(GD32VF103)
+#        define USE_GPIOV1
+#        define USE_I2CV1
+#        define PAL_MODE_ALTERNATE_OPENDRAIN PAL_MODE_GD32_ALTERNATE_OPENDRAIN
+#        define PAL_MODE_ALTERNATE_PUSHPULL PAL_MODE_GD32_ALTERNATE_PUSHPULL
+#    endif
+#endif
+
+#if defined(GD32VF103)
+/* This chip has the same API as STM32F103, but uses different names for literally the same thing.
+ * As of 4.7.2021 QMK is tailored to use STM32 defines/names, for compatibility sake
+ * we just redefine the GD32 names. */
+#    include "gd32v_compatibility.h"
+#endif
+
 // teensy compatibility
 #if defined(MCU_KINETIS)
 #    define CPU_CLOCK KINETIS_SYSCLK_FREQUENCY
diff --git a/tmk_core/common/chibios/eeprom_stm32_defs.h b/tmk_core/common/chibios/eeprom_stm32_defs.h
index 349979626..66904f247 100644
--- a/tmk_core/common/chibios/eeprom_stm32_defs.h
+++ b/tmk_core/common/chibios/eeprom_stm32_defs.h
@@ -18,7 +18,7 @@
 #include <hal.h>
 
 #if !defined(FEE_PAGE_SIZE) || !defined(FEE_PAGE_COUNT)
-#    if defined(STM32F103xB) || defined(STM32F042x6)
+#    if defined(STM32F103xB) || defined(STM32F042x6) || defined(GD32VF103C8) || defined(GD32VF103CB)
 #        ifndef FEE_PAGE_SIZE
 #            define FEE_PAGE_SIZE 0x400  // Page size = 1KByte
 #        endif
@@ -45,7 +45,9 @@
 #if !defined(FEE_MCU_FLASH_SIZE)
 #    if defined(STM32F042x6)
 #        define FEE_MCU_FLASH_SIZE 32  // Size in Kb
-#    elif defined(STM32F103xB) || defined(STM32F072xB) || defined(STM32F070xB)
+#    elif defined(GD32VF103C8)
+#        define FEE_MCU_FLASH_SIZE 64  // Size in Kb
+#    elif defined(STM32F103xB) || defined(STM32F072xB) || defined(STM32F070xB) || defined(GD32VF103CB)
 #        define FEE_MCU_FLASH_SIZE 128  // Size in Kb
 #    elif defined(STM32F303xC) || defined(STM32F401xC)
 #        define FEE_MCU_FLASH_SIZE 256  // Size in Kb
diff --git a/tmk_core/common/chibios/flash_stm32.c b/tmk_core/common/chibios/flash_stm32.c
index 35fb0eebd..72c41b8b7 100644
--- a/tmk_core/common/chibios/flash_stm32.c
+++ b/tmk_core/common/chibios/flash_stm32.c
@@ -23,6 +23,11 @@
 #    define FLASH_SR_WRPERR FLASH_SR_WRPRTERR
 #endif
 
+#if defined(MCU_GD32V)
+/* GigaDevice GD32VF103 is a STM32F103 clone at heart. */
+#    include "gd32v_compatibility.h"
+#endif
+
 #if defined(STM32F4XX)
 #    define FLASH_SR_PGERR (FLASH_SR_PGSERR | FLASH_SR_PGPERR | FLASH_SR_PGAERR)
 
diff --git a/tmk_core/common/chibios/gd32v_compatibility.h b/tmk_core/common/chibios/gd32v_compatibility.h
new file mode 100644
index 000000000..f4dcfd8c5
--- /dev/null
+++ b/tmk_core/common/chibios/gd32v_compatibility.h
@@ -0,0 +1,120 @@
+/* Copyright 2021 QMK
+ *
+ * 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
+
+/* GD32VF103 has the same API as STM32F103, but uses different names for literally the same thing.
+ * As of 23.7.2021 QMK is tailored to use STM32 defines/names, for compatibility sake
+ * we just redefine the GD32 names. */
+
+/* Close your eyes kids. */
+#define MCU_STM32
+
+/* AFIO redefines */
+#define MAPR PCF0
+#define AFIO_MAPR_USART1_REMAP AFIO_PCF0_USART0_REMAP
+#define AFIO_MAPR_USART2_REMAP AFIO_PCF0_USART1_REMAP
+#define AFIO_MAPR_USART3_REMAP_PARTIALREMAP AFIO_PCF0_USART2_REMAP_PARTIALREMAP
+#define AFIO_MAPR_USART3_REMAP_FULLREMAP AFIO_PCF0_USART2_REMAP_FULLREMAP
+
+/* DMA redefines. */
+#define STM32_DMA_STREAM(stream) GD32_DMA_STREAM(stream)
+#define STM32_DMA_STREAM_ID(peripheral, channel) GD32_DMA_STREAM_ID(peripheral - 1, channel - 1)
+#define STM32_DMA_CR_DIR_M2P GD32_DMA_CTL_DIR_M2P
+#define STM32_DMA_CR_PSIZE_WORD GD32_DMA_CTL_PWIDTH_WORD
+#define STM32_DMA_CR_MSIZE_WORD GD32_DMA_CTL_MWIDTH_WORD
+#define STM32_DMA_CR_MINC GD32_DMA_CTL_MNAGA
+#define STM32_DMA_CR_CIRC GD32_DMA_CTL_CMEN
+#define STM32_DMA_CR_PL GD32_DMA_CTL_PRIO
+#define STM32_DMA_CR_CHSEL GD32_DMA_CTL_CHSEL
+#define cr1 ctl0
+#define cr2 ctl1
+#define cr3 ctl2
+#define dier dmainten
+
+/* ADC redefines */
+#if HAL_USE_ADC
+#    define STM32_ADC_USE_ADC1 GD32_ADC_USE_ADC0
+
+#    define smpr1 sampt0
+#    define smpr2 sampt1
+#    define sqr1 rsq0
+#    define sqr2 rsq1
+#    define sqr3 rsq2
+
+#    define ADC_SMPR2_SMP_AN0 ADC_SAMPT1_SMP_SPT0
+#    define ADC_SMPR2_SMP_AN1 ADC_SAMPT1_SMP_SPT1
+#    define ADC_SMPR2_SMP_AN2 ADC_SAMPT1_SMP_SPT2
+#    define ADC_SMPR2_SMP_AN3 ADC_SAMPT1_SMP_SPT3
+#    define ADC_SMPR2_SMP_AN4 ADC_SAMPT1_SMP_SPT4
+#    define ADC_SMPR2_SMP_AN5 ADC_SAMPT1_SMP_SPT5
+#    define ADC_SMPR2_SMP_AN6 ADC_SAMPT1_SMP_SPT6
+#    define ADC_SMPR2_SMP_AN7 ADC_SAMPT1_SMP_SPT7
+#    define ADC_SMPR2_SMP_AN8 ADC_SAMPT1_SMP_SPT8
+#    define ADC_SMPR2_SMP_AN9 ADC_SAMPT1_SMP_SPT9
+
+#    define ADC_SMPR1_SMP_AN10 ADC_SAMPT0_SMP_SPT10
+#    define ADC_SMPR1_SMP_AN11 ADC_SAMPT0_SMP_SPT11
+#    define ADC_SMPR1_SMP_AN12 ADC_SAMPT0_SMP_SPT12
+#    define ADC_SMPR1_SMP_AN13 ADC_SAMPT0_SMP_SPT13
+#    define ADC_SMPR1_SMP_AN14 ADC_SAMPT0_SMP_SPT14
+#    define ADC_SMPR1_SMP_AN15 ADC_SAMPT0_SMP_SPT15
+
+#    define ADC_SQR3_SQ1_N ADC_RSQ2_RSQ1_N
+#endif
+
+/* FLASH redefines */
+#if defined(EEPROM_ENABLE)
+#    define SR STAT
+#    define FLASH_SR_BSY FLASH_STAT_BUSY
+#    define FLASH_SR_PGERR FLASH_STAT_PGERR
+#    define FLASH_SR_EOP FLASH_STAT_ENDF
+#    define FLASH_SR_WRPRTERR FLASH_STAT_WPERR
+#    define FLASH_SR_WRPERR FLASH_SR_WRPRTERR
+#    define FLASH_OBR_OPTERR FLASH_OBSTAT_OBERR
+#    define AR ADDR
+#    define CR CTL
+#    define FLASH_CR_PER FLASH_CTL_PER
+#    define FLASH_CR_STRT FLASH_CTL_START
+#    define FLASH_CR_LOCK FLASH_CTL_LK
+#    define FLASH_CR_PG FLASH_CTL_PG
+#    define KEYR KEY
+#endif
+
+/* Serial USART redefines. */
+#if HAL_USE_SERIAL
+#    if !defined(SERIAL_USART_CR1)
+#        define SERIAL_USART_CR1 (USART_CTL0_PCEN | USART_CTL0_PM | USART_CTL0_WL)  // parity enable, odd parity, 9 bit length
+#    endif
+#    if !defined(SERIAL_USART_CR2)
+#        define SERIAL_USART_CR2 (USART_CTL1_STB_1)  // 2 stop bits
+#    endif
+#    if !defined(SERIAL_USART_CR3)
+#        define SERIAL_USART_CR3 0x0
+#    endif
+#    define USART_CR3_HDSEL USART_CTL2_HDEN
+#    define CCR CHCV
+#endif
+
+/* SPI redefines. */
+#if HAL_USE_SPI
+#    define SPI_CR1_LSBFIRST SPI_CTL0_LF
+#    define SPI_CR1_CPHA SPI_CTL0_CKPH
+#    define SPI_CR1_CPOL SPI_CTL0_CKPL
+#    define SPI_CR1_BR_0 SPI_CTL0_PSC_0
+#    define SPI_CR1_BR_1 SPI_CTL0_PSC_1
+#    define SPI_CR1_BR_2 SPI_CTL0_PSC_2
+#endif
diff --git a/tmk_core/common/chibios/syscall-fallbacks.c b/tmk_core/common/chibios/syscall-fallbacks.c
index 739017ae1..4569879c7 100644
--- a/tmk_core/common/chibios/syscall-fallbacks.c
+++ b/tmk_core/common/chibios/syscall-fallbacks.c
@@ -18,6 +18,12 @@
 #include <sys/stat.h>
 #include <sys/types.h>
 
+/* To compile the ChibiOS syscall stubs with picolibc
+ * the _reent struct has to be defined. */
+#if defined(USE_PICOLIBC)
+struct _reent;
+#endif
+
 #pragma GCC diagnostic ignored "-Wmissing-prototypes"
 
 __attribute__((weak, used)) int _open_r(struct _reent *r, const char *path, int flag, int m) {