From be4224bb263259125d10ac11d8bd5806343de441 Mon Sep 17 00:00:00 2001
From: dragonmux <git@dragonmux.network>
Date: Fri, 10 Nov 2023 14:27:07 +0000
Subject: [PATCH] esp32c3: Split out the target preparation (switching off the
 WDTs) from discovery so we can halt them early enough for discovery to be
 more reliable

---
 src/target/esp32c3.c      | 24 +++++++++++++++++++++---
 src/target/riscv_debug.c  |  6 ++++++
 src/target/target_probe.c |  5 +++++
 src/target/target_probe.h |  1 +
 4 files changed, 33 insertions(+), 3 deletions(-)

diff --git a/src/target/esp32c3.c b/src/target/esp32c3.c
index 98300b5cfd5..43bbff65374 100644
--- a/src/target/esp32c3.c
+++ b/src/target/esp32c3.c
@@ -37,6 +37,7 @@
 #include "riscv_debug.h"
 #include "spi.h"
 #include "sfdp.h"
+#include "jep106.h"
 
 #define ESP32_C3_ARCH_ID 0x80000001U
 #define ESP32_C3_IMPL_ID 0x00000001U
@@ -149,21 +150,38 @@ static bool esp32c3_exit_flash_mode(target_s *target);
 static bool esp32c3_spi_flash_erase(target_flash_s *flash, target_addr_t addr, size_t length);
 static bool esp32c3_spi_flash_write(target_flash_s *flash, target_addr_t dest, const void *src, size_t length);
 
-bool esp32c3_probe(target_s *const target)
+/* Make an ESP32-C3 ready for probe operations having identified one */
+bool esp32c3_target_prepare(target_s *const target)
 {
 	const riscv_hart_s *const hart = riscv_hart_struct(target);
 	/* Seems that the best we can do is check the marchid and mimplid register values */
-	if (hart->archid != ESP32_C3_ARCH_ID || hart->implid != ESP32_C3_IMPL_ID)
+	if (target->designer_code != JEP106_MANUFACTURER_ESPRESSIF || hart->archid != ESP32_C3_ARCH_ID ||
+		hart->implid != ESP32_C3_IMPL_ID)
 		return false;
 
+	/* Allocate the private structure here so we can store the WDT states */
 	esp32c3_priv_s *const priv = calloc(1, sizeof(esp32c3_priv_s));
 	if (!priv) { /* calloc failed: heap exhaustion */
 		DEBUG_ERROR("calloc: failed in %s\n", __func__);
 		return false;
 	}
 	target->target_storage = priv;
-	target->driver = "ESP32-C3";
+	/* Prepare the target for memory IO */
+	target->mem_read = riscv32_mem_read;
+	target->mem_write = riscv32_mem_write;
+	/* Now disable the WDTs so the stop causing problems ready for discovering trigger slots, etc */
 	esp32c3_disable_wdts(target);
+	return true;
+}
+
+bool esp32c3_probe(target_s *const target)
+{
+	const riscv_hart_s *const hart = riscv_hart_struct(target);
+	/* Seems that the best we can do is check the marchid and mimplid register values */
+	if (hart->archid != ESP32_C3_ARCH_ID || hart->implid != ESP32_C3_IMPL_ID)
+		return false;
+
+	target->driver = "ESP32-C3";
 
 	/* We have to provide our own halt/resume functions to take care of the WDTs as they cause Problems */
 	target->halt_request = esp32c3_halt_request;
diff --git a/src/target/riscv_debug.c b/src/target/riscv_debug.c
index 944340195b8..8bca58f9739 100644
--- a/src/target/riscv_debug.c
+++ b/src/target/riscv_debug.c
@@ -385,6 +385,12 @@ static bool riscv_hart_init(riscv_hart_s *const hart)
 	target->designer_code = hart->vendorid ? hart->vendorid : hart->dbg_module->dmi_bus->designer_code;
 	target->cpuid = hart->archid;
 
+	/*
+	 * Now we've identified the target, and before we can do things like trigger discovery
+	 * we need to first run any target-specific setup (eg, halting the WDTs on the ESP32-C3)
+	 * so the next steps won't get screwed up by them.
+	 */
+	esp32c3_target_prepare(target);
 	/* Now we're in a safe environment, leasurely read out the triggers, etc. */
 	riscv_hart_discover_triggers(hart);
 
diff --git a/src/target/target_probe.c b/src/target/target_probe.c
index a5511c18c6a..343a170f17d 100644
--- a/src/target/target_probe.c
+++ b/src/target/target_probe.c
@@ -129,3 +129,8 @@ TARGET_PROBE_WEAK_NOP(zynq7_probe)
 TARGET_PROBE_WEAK_NOP(esp32c3_probe)
 
 LPC55_DP_PREPARE_WEAK_NOP(lpc55_dp_prepare)
+/*
+ * This isn't actually a probe routine, but it shares its signature with them,
+ * so uses the same no-op stub because we can get away with that.
+ */
+TARGET_PROBE_WEAK_NOP(esp32c3_target_prepare)
diff --git a/src/target/target_probe.h b/src/target/target_probe.h
index ba768498bd5..57d95e8d4f8 100644
--- a/src/target/target_probe.h
+++ b/src/target/target_probe.h
@@ -97,5 +97,6 @@ bool zynq7_probe(target_s *target);
 bool esp32c3_probe(target_s *target);
 
 void lpc55_dp_prepare(adiv5_debug_port_s *dp);
+bool esp32c3_target_prepare(target_s *target);
 
 #endif /* TARGET_TARGET_PROBE_H */