vfs: add support for semihosting on ESP32-C3

2021-01-06 00:26:07 +01:00
parent 991874ae43
commit 876f4d6a1c
11 changed files with 464 additions and 260 deletions
@@ -0,0 +1,60 @@
+/*
+ * SPDX-FileCopyrightText: 2022 Espressif Systems (Shanghai) CO LTD
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#pragma once
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/**
+ * @brief Perform semihosting call and retrieve errno
+ *
+ * @param id    semihosting call number
+ * @param data  data block to pass to the host; number of items and their
+ *              meaning depends on the semihosting call. See the spec for
+ *              details.
+ *              On Xtensa, this function assumes that the array contains at
+ *              least 4 elements, but no effort is made to guarantee that.
+ *              Passing a shorter array will still work, as long as it contains
+ *              sufficient values for the corresponding semihosting call.
+ * @param[out] out_errno  output, errno value from the host. Only set if
+ *                        the return value is negative.
+ * @return   return value from the host
+ */
+static inline long semihosting_call(long id, long *data, int *out_errno)    // NOLINT(readability-non-const-parameter)
+{
+    long host_ret;
+    long host_errno;
+    /* The break instruction operands should be (1, 14) according to the ISA manual.
+     * We keep (1, 1) for compatibility, until OpenOCD is updated to support both
+     * conventions.
+     */
+    __asm__ __volatile__ (
+        "mov a2, %[sys_nr]\n" \
+        "mov a3, %[arg1]\n" \
+        "mov a4, %[arg2]\n" \
+        "mov a5, %[arg3]\n" \
+        "mov a6, %[arg4]\n" \
+        "break 1, 1\n" \
+        "mov %[host_ret], a2\n" \
+        "mov %[host_errno], a3\n" \
+        :[host_ret]"=r"(host_ret), [host_errno]"=r"(host_errno)
+        :[sys_nr]"r"(id),
+        [arg1]"r"(data[0]),
+        [arg2]"r"(data[1]),
+        [arg3]"r"(data[2]),
+        [arg4]"r"(data[3])
+        :"a2", "a3", "a4", "a5", "a6");
+    if (host_ret < 0) {
+        *out_errno = host_errno;
+    }
+    return host_ret;
+}
+
+#ifdef __cplusplus
+}
+#endif