target/espressif: add semihosting support

ARM semihosting + some custom syscalls implemented for
Espressif chips (ESP32, ESP32-S2, ESP32-S3)

Signed-off-by: Erhan Kurubas <erhan.kurubas@espressif.com>
Change-Id: Ic8174cf1cd344fa16d619b7b8405c9650e869443
Reviewed-on: https://review.openocd.org/c/openocd/+/7074
Tested-by: jenkins
Reviewed-by: Antonio Borneo <borneo.antonio@gmail.com>

src/target/espressif/esp_semihosting.c

@@ -0,0 +1,127 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+
+/***************************************************************************
+ *   Semihosting API for Espressif chips                                   *
+ *   Copyright (C) 2022 Espressif Systems Ltd.                             *
+ ***************************************************************************/
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#endif
+
+#include <helper/log.h>
+#include <target/target.h>
+#include <target/semihosting_common.h>
+#include "esp_semihosting.h"
+#include "esp_xtensa.h"
+
+struct esp_semihost_data *target_to_esp_semihost_data(struct target *target)
+{
+	const char *arch = target_get_gdb_arch(target);
+	if (arch) {
+		if (strncmp(arch, "xtensa", 6) == 0)
+			return &target_to_esp_xtensa(target)->semihost;
+		/* TODO: add riscv */
+	}
+	LOG_ERROR("Unknown target arch!");
+	return NULL;
+}
+
+int esp_semihosting_sys_seek(struct target *target, uint64_t fd, uint32_t pos, size_t whence)
+{
+	struct semihosting *semihosting = target->semihosting;
+
+	semihosting->result = lseek(fd, pos, whence);
+	semihosting->sys_errno = errno;
+	LOG_TARGET_DEBUG(target, "lseek(%" PRIx64 ", %" PRIu32 " %" PRId64 ")=%d", fd, pos, semihosting->result, errno);
+	return ERROR_OK;
+}
+
+int esp_semihosting_common(struct target *target)
+{
+	struct semihosting *semihosting = target->semihosting;
+	if (!semihosting)
+		/* Silently ignore if the semihosting field was not set. */
+		return ERROR_OK;
+
+	int retval = ERROR_NOT_IMPLEMENTED;
+
+	/* Enough space to hold 4 long words. */
+	uint8_t fields[4 * 8];
+
+	/*
+	 * By default return an error.
+	 * The actual result must be set by each function
+	 */
+	semihosting->result = -1;
+	semihosting->sys_errno = EIO;
+
+	LOG_TARGET_DEBUG(target, "op=0x%x, param=0x%" PRIx64, semihosting->op, semihosting->param);
+
+	switch (semihosting->op) {
+	case ESP_SEMIHOSTING_SYS_DRV_INFO:
+		/* Return success to make esp-idf application happy */
+		retval = ERROR_OK;
+		semihosting->result = 0;
+		semihosting->sys_errno = 0;
+		break;
+
+	case ESP_SEMIHOSTING_SYS_SEEK:
+		retval = semihosting_read_fields(target, 3, fields);
+		if (retval == ERROR_OK) {
+			uint64_t fd = semihosting_get_field(target, 0, fields);
+			uint32_t pos = semihosting_get_field(target, 1, fields);
+			size_t whence = semihosting_get_field(target, 2, fields);
+			retval = esp_semihosting_sys_seek(target, fd, pos, whence);
+		}
+		break;
+
+	case ESP_SEMIHOSTING_SYS_APPTRACE_INIT:
+	case ESP_SEMIHOSTING_SYS_DEBUG_STUBS_INIT:
+	case ESP_SEMIHOSTING_SYS_BREAKPOINT_SET:
+	case ESP_SEMIHOSTING_SYS_WATCHPOINT_SET:
+		/* For the time being only riscv chips support these commands
+		 * TODO: invoke riscv custom command handler */
+		break;
+	}
+
+	return retval;
+}
+
+int esp_semihosting_basedir_command(struct command_invocation *cmd)
+{
+	struct target *target = get_current_target(CMD_CTX);
+
+	if (!target) {
+		LOG_ERROR("No target selected");
+		return ERROR_FAIL;
+	}
+
+	struct semihosting *semihosting = target->semihosting;
+	if (!semihosting) {
+		command_print(CMD, "semihosting not supported for current target");
+		return ERROR_FAIL;
+	}
+
+	if (!semihosting->is_active) {
+		if (semihosting->setup(target, true) != ERROR_OK) {
+			LOG_ERROR("Failed to Configure semihosting");
+			return ERROR_FAIL;
+		}
+		semihosting->is_active = true;
+	}
+
+	if (CMD_ARGC > 0) {
+		free(semihosting->basedir);
+		semihosting->basedir = strdup(CMD_ARGV[0]);
+		if (!semihosting->basedir) {
+			command_print(CMD, "semihosting failed to allocate memory for basedir!");
+			return ERROR_FAIL;
+		}
+	}
+
+	command_print(CMD, "DEPRECATED! semihosting base dir: %s",
+		semihosting->basedir ? semihosting->basedir : "");
+
+	return ERROR_OK;
+}