riscv_debug: Transform JTAG ID Code designer into JEP-106 internal format and store it as a DMI designer code

Author: perigoso

src/target/adiv5.h

@@ -167,6 +167,11 @@
 #define JTAG_IDCODE_PARTNO_MASK     (0xffffU << JTAG_IDCODE_PARTNO_OFFSET)
 #define JTAG_IDCODE_DESIGNER_OFFSET 1U
 #define JTAG_IDCODE_DESIGNER_MASK   (0x7ffU << JTAG_IDCODE_DESIGNER_OFFSET)
+/* Bits 10:7 - JEP-106 Continuation code */
+/* Bits 6:0 - JEP-106 Identity code */
+#define JTAG_IDCODE_DESIGNER_JEP106_CONT_OFFSET 7U
+#define JTAG_IDCODE_DESIGNER_JEP106_CONT_MASK   (0xfU << ADIV5_DP_DESIGNER_JEP106_CONT_OFFSET)
+#define JTAG_IDCODE_DESIGNER_JEP106_CODE_MASK   (0x7fU)
 
 #define JTAG_IDCODE_ARM_DPv0 UINT32_C(0x4ba00477)
 

src/target/riscv_debug.c

@@ -352,10 +352,8 @@ static bool riscv_hart_init(riscv_hart_s *const hart)
 		return true;
 	}
 
-	/* If the hart implements mvendorid, this gives us the JEP-106, otherwise use the JTAG IDCode */
-	target->designer_code = hart->vendorid ?
-		hart->vendorid :
-		((hart->dbg_module->dmi_bus->idcode & JTAG_IDCODE_DESIGNER_MASK) >> JTAG_IDCODE_DESIGNER_OFFSET);
+	/* If the hart implements mvendorid, this gives us the JEP-106, otherwise use the DTM designer code */
+	target->designer_code = hart->vendorid ? hart->vendorid : hart->dbg_module->dmi_bus->designer_code;
 	target->cpuid = hart->archid;
 
 	riscv_hart_discover_triggers(hart);

src/target/riscv_debug.h

@@ -90,7 +90,7 @@ typedef struct riscv_dmi riscv_dmi_s;
 struct riscv_dmi {
 	uint32_t ref_count;
 
-	uint32_t idcode;
+	uint16_t designer_code;
 	riscv_debug_version_e version;
 
 	uint8_t dev_index;

src/target/riscv_jtag_dtm.c

@@ -35,6 +35,7 @@
 #include "jtag_scan.h"
 #include "jtagtap.h"
 #include "riscv_debug.h"
+#include "adiv5.h"
 
 #define IR_DTMCS  0x10U
 #define IR_DMI    0x11U
@@ -75,12 +76,23 @@ void riscv_jtag_dtm_handler(const uint8_t dev_index)
 	}
 
 	/* Setup and try to discover the DMI bus */
-	dmi->idcode = jtag_devs[dev_index].jd_idcode;
 	dmi->dev_index = dev_index;
+	/*
+	 * The code in JTAG_IDCODE_DESIGNER is in the form
+	 * Bits 10:7 - JEP-106 Continuation code
+	 * Bits 6:0 - JEP-106 Identity code
+	 * here we convert it to our internal representation, See JEP-106 code list
+	 */
+	const uint16_t designer =
+		(jtag_devs[dev_index].jd_idcode & JTAG_IDCODE_DESIGNER_MASK) >> JTAG_IDCODE_DESIGNER_OFFSET;
+	dmi->designer_code =
+		(designer & JTAG_IDCODE_DESIGNER_JEP106_CONT_MASK) << 1U | (designer & JTAG_IDCODE_DESIGNER_JEP106_CODE_MASK);
+
 	riscv_jtag_dtm_init(dmi);
 	/* If we failed to find any DMs or Harts, free the structure */
 	if (!dmi->ref_count)
 		free(dmi);
+
 	/* Reset the JTAG machinary back to bypass to scan the next device in the chain */
 	jtag_dev_write_ir(dev_index, IR_BYPASS);
 }