hosted/remote/protocol_v4: Add JTAG ensure idle command (!JI#)

Author: ALTracer

src/platforms/hosted/remote/protocol_v4.c

@@ -108,6 +108,7 @@ bool remote_v4_adiv5_init(adiv5_debug_port_s *const dp)
 	dp->ap_write = remote_v4_adiv5_ap_write;
 	dp->mem_read = remote_v4_adiv5_mem_read_bytes;
 	dp->mem_write = remote_v4_adiv5_mem_write_bytes;
+	dp->ensure_idle = remote_v4_jtag_ensure_idle;
 	return true;
 }
 
@@ -172,3 +173,18 @@ uint64_t remote_v4_supported_families(void)
 		return remote_decode_response(buffer + 1U, 8U);
 	return 0U;
 }
+
+void remote_v4_jtag_ensure_idle(adiv5_debug_port_s *dp)
+{
+	/* Ask remote_dp !JI# to set IR cache to BYPASS (because a reset happened) */
+	platform_buffer_write(REMOTE_JTAG_ENSURE_IDLE_STR, sizeof(REMOTE_JTAG_ENSURE_IDLE_STR));
+	char buffer[REMOTE_MAX_MSG_SIZE];
+	/* Read back the answer and check for errors */
+	const int length = platform_buffer_read(buffer, REMOTE_MAX_MSG_SIZE);
+	if (length < 1 || buffer[0U] != REMOTE_RESP_OK) {
+		DEBUG_ERROR("%s failed, error %s\n", __func__, length ? buffer + 1 : "with communication");
+		return;
+	}
+	jtag_devs[dp->dev_index].current_ir = 0xffU;
+	jtagtap_return_idle(1);
+}

src/platforms/hosted/remote/protocol_v4.h

@@ -43,6 +43,7 @@ bool remote_v4_init(void);
 bool remote_v4_adiv5_init(adiv5_debug_port_s *dp);
 bool remote_v4_adiv6_init(adiv5_debug_port_s *dp);
 bool remote_v4_riscv_jtag_init(riscv_dmi_s *dmi);
+void remote_v4_jtag_ensure_idle(adiv5_debug_port_s *dp);
 
 uint64_t remote_v4_supported_architectures(void);
 uint64_t remote_v4_supported_families(void);

src/platforms/hosted/remote/protocol_v4_defs.h

@@ -154,6 +154,13 @@
 		REMOTE_SOM, REMOTE_ADIV5_PACKET, REMOTE_DP_TARGETSEL, REMOTE_ADIV5_DATA, REMOTE_EOM, 0 \
 	}
 
+#define REMOTE_JTAG_ENSURE_IDLE 'I'
+#define REMOTE_JTAG_ENSURE_IDLE_STR                                            \
+	(char[])                                                                   \
+	{                                                                          \
+		REMOTE_SOM, REMOTE_JTAG_PACKET, REMOTE_JTAG_ENSURE_IDLE, REMOTE_EOM, 0 \
+	}
+
 /* ADIv6 acceleration protocol elements */
 #define REMOTE_ADIV6_PACKET '6'