Add connecting MCU to JTAG support for GW1NSR-4C

src/device.hpp

@@ -52,6 +52,8 @@ class Device {
 		virtual int  idCode() = 0;
 		virtual void reset();
 
+		virtual bool connectJtagToMCU() {return false;}
+
 	protected:
 		Jtag *_jtag;
 		std::string _filename;

src/gowin.cpp

@@ -58,6 +58,7 @@ using namespace std;
 #  define STATUS_FLASH_LOCK			(1 << 17)
 #define EF_PROGRAM			0x71
 #define EFLASH_ERASE		0x75
+#define SWITCH_TO_MCU_JTAG		0x7a
 
 /* BSCAN spi (external flash) (see below for details) */
 /* most common pins def */
@@ -576,6 +577,12 @@ bool Gowin::flashFLASH(uint32_t page, uint8_t *data, int length)
 	return true;
 }
 
+bool Gowin::connectJtagToMCU()
+{
+	wr_rd(SWITCH_TO_MCU_JTAG, NULL, 0, NULL, 0);
+	return true;
+}
+
 /* TN653 p. 9 */
 bool Gowin::flashSRAM(uint8_t *data, int length)
 {

src/gowin.hpp

@@ -26,6 +26,7 @@ class Gowin: public Device, SPIInterface {
 		void reset() override;
 		void program(unsigned int offset, bool unprotect_flash) override;
 		void programFlash();
+		bool connectJtagToMCU() override;
 
 		/* spi interface */
 		virtual bool protect_flash(uint32_t len) override {

src/main.cpp

@@ -79,6 +79,7 @@ struct arguments {
 	int port;
 	string interface;
 	string mcufw;
+	bool conmcu;
 };
 
 int run_xvc_server(const struct arguments &args, const cable_t &cable,
@@ -538,6 +539,13 @@ int main(int argc, char **argv)
 		}
 	}
 
+	if (args.conmcu == true) {
+		fpga->connectJtagToMCU();
+		delete(fpga);
+		delete(jtag);
+		return EXIT_SUCCESS;
+	}
+
 	/* unprotect SPI flash */
 	if (args.unprotect_flash && args.bit_file.empty()) {
 		fpga->unprotect_flash();
@@ -716,6 +724,8 @@ int parse_opt(int argc, char **argv, struct arguments *args, jtag_pins_conf_t *p
 				cxxopts::value<int>(args->port))
 			("mcufw", "Microcontroller firmware",
 				cxxopts::value<std::string>(args->mcufw))
+			("conmcu", "Connect JTAG to MCU",
+				cxxopts::value<bool>(args->conmcu))
 			("V,Version", "Print program version");
 
 		options.parse_positional({"bitstream"});
@@ -846,7 +856,8 @@ int parse_opt(int argc, char **argv, struct arguments *args, jtag_pins_conf_t *p
 			!args->protect_flash &&
 			!args->unprotect_flash &&
 			!args->xvc &&
-			!args->reset) {
+			!args->reset &&
+			!args->conmcu) {
 			printError("Error: bitfile not specified");
 			cout << options.help() << endl;
 			throw std::exception();