feat(fdt): introduce wrapper function to read DT UUIDs
TF-A does not have the capability to read UUIDs in string form
from the device tree. This capability is useful for readability,
so add a wrapper function, fdtw_read_uuid() to parse UUIDs from
the DT.
This function should parse a string of the form:
"aabbccdd-eeff-4099-8877-665544332211"
to the byte sequence in memory:
[aa bb cc dd ee ff 40 99 88 77 66 55 44 33 22 11]
Change-Id: I99a92fbeb40f4f4713f3458b36cb3863354d2bdf
Signed-off-by: David Horstmann <david.horstmann@arm.com>
diff --git a/common/fdt_wrappers.c b/common/fdt_wrappers.c
index 5aad14e..dd7a0fa 100644
--- a/common/fdt_wrappers.c
+++ b/common/fdt_wrappers.c
@@ -1,5 +1,5 @@
/*
- * Copyright (c) 2018-2020, ARM Limited and Contributors. All rights reserved.
+ * Copyright (c) 2018-2021, ARM Limited and Contributors. All rights reserved.
*
* SPDX-License-Identifier: BSD-3-Clause
*/
@@ -7,12 +7,14 @@
/* Helper functions to offer easier navigation of Device Tree Blob */
#include <assert.h>
+#include <errno.h>
#include <string.h>
#include <libfdt.h>
#include <common/debug.h>
#include <common/fdt_wrappers.h>
+#include <common/uuid.h>
/*
* Read cells from a given property of the given node. Any number of 32-bit
@@ -152,6 +154,39 @@
}
/*
+ * Read UUID from a given property of the given node. Returns 0 on success,
+ * and a negative value upon error.
+ */
+int fdtw_read_uuid(const void *dtb, int node, const char *prop,
+ unsigned int length, uint8_t *uuid)
+{
+ /* Buffer for UUID string (plus NUL terminator) */
+ char uuid_string[UUID_STRING_LENGTH + 1U];
+ int err;
+
+ assert(dtb != NULL);
+ assert(prop != NULL);
+ assert(uuid != NULL);
+ assert(node >= 0);
+
+ if (length < UUID_BYTES_LENGTH) {
+ return -EINVAL;
+ }
+
+ err = fdtw_read_string(dtb, node, prop, uuid_string,
+ UUID_STRING_LENGTH + 1U);
+ if (err != 0) {
+ return err;
+ }
+
+ if (read_uuid(uuid, uuid_string) != 0) {
+ return -FDT_ERR_BADVALUE;
+ }
+
+ return 0;
+}
+
+/*
* Write cells in place to a given property of the given node. At most 2 cells
* of the property are written. Returns 0 on success, and -1 upon error.
*/
diff --git a/common/uuid.c b/common/uuid.c
new file mode 100644
index 0000000..dd3c7b0
--- /dev/null
+++ b/common/uuid.c
@@ -0,0 +1,133 @@
+/*
+ * Copyright (c) 2021, Arm Limited and Contributors. All rights reserved.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#include <assert.h>
+#include <errno.h>
+#include <stdint.h>
+#include <string.h>
+
+#include <common/debug.h>
+#include <common/uuid.h>
+
+/* Return the hex nibble value of a char */
+static int8_t hex_val(char hex)
+{
+ int8_t val = 0;
+
+ if ((hex >= '0') && (hex <= '9')) {
+ val = (int8_t)(hex - '0');
+ } else if ((hex >= 'a') && (hex <= 'f')) {
+ val = (int8_t)(hex - 'a' + 0xa);
+ } else if ((hex >= 'A') && (hex <= 'F')) {
+ val = (int8_t)(hex - 'A' + 0xa);
+ } else {
+ val = -1;
+ }
+
+ return val;
+}
+
+/*
+ * Read hex_src_len hex characters from hex_src, convert to bytes and
+ * store in buffer pointed to by dest
+ */
+static int read_hex(uint8_t *dest, char *hex_src, unsigned int hex_src_len)
+{
+ int8_t nibble;
+ uint8_t byte;
+
+ /*
+ * The string length must be a multiple of 2 to represent an
+ * exact number of bytes.
+ */
+ assert((hex_src_len % 2U) == 0U);
+
+ for (unsigned int i = 0U; i < (hex_src_len / 2U); i++) {
+ nibble = 0;
+ byte = 0U;
+
+ nibble = hex_val(hex_src[2U * i]);
+ if (nibble < 0) {
+ return -1;
+ }
+ byte = (uint8_t)nibble;
+ byte <<= 4U;
+
+ nibble = hex_val(hex_src[(2U * i) + 1U]);
+ if (nibble < 0) {
+ return -1;
+ }
+ byte |= (uint8_t)nibble;
+
+ *dest = byte;
+ dest++;
+ }
+
+ return 0;
+}
+
+/* Parse UUIDs of the form aabbccdd-eeff-4099-8877-665544332211 */
+int read_uuid(uint8_t *dest, char *uuid)
+{
+ int err;
+
+ /* Check that we have enough characters */
+ if (strnlen(uuid, UUID_STRING_LENGTH) != UUID_STRING_LENGTH) {
+ WARN("UUID string is too short\n");
+ return -EINVAL;
+ }
+
+ /* aabbccdd */
+ err = read_hex(dest, uuid, 8);
+ uuid += 8;
+ dest += 4;
+
+ /* Check for '-' */
+ err |= ((*uuid == '-') ? 0 : -1);
+ uuid++;
+
+ /* eeff */
+ err |= read_hex(dest, uuid, 4);
+ uuid += 4;
+ dest += 2;
+
+ /* Check for '-' */
+ err |= ((*uuid == '-') ? 0 : -1);
+ uuid++;
+
+ /* 4099 */
+ err |= read_hex(dest, uuid, 4);
+ uuid += 4;
+ dest += 2;
+
+ /* Check for '-' */
+ err |= ((*uuid == '-') ? 0 : -1);
+ uuid++;
+
+ /* 8877 */
+ err |= read_hex(dest, uuid, 4);
+ uuid += 4;
+ dest += 2;
+
+ /* Check for '-' */
+ err |= ((*uuid == '-') ? 0 : -1);
+ uuid++;
+
+ /* 665544332211 */
+ err |= read_hex(dest, uuid, 12);
+ uuid += 12;
+ dest += 6;
+
+ if (err < 0) {
+ WARN("Error parsing UUID\n");
+ /* Clear the buffer on error */
+ memset((void *)dest, '\0', UUID_BYTES_LENGTH * sizeof(uint8_t));
+ return -EINVAL;
+ }
+
+ return 0;
+}
+
diff --git a/include/common/fdt_wrappers.h b/include/common/fdt_wrappers.h
index a571092..e8b3933 100644
--- a/include/common/fdt_wrappers.h
+++ b/include/common/fdt_wrappers.h
@@ -1,5 +1,5 @@
/*
- * Copyright (c) 2018-2020, ARM Limited and Contributors. All rights reserved.
+ * Copyright (c) 2018-2021, ARM Limited and Contributors. All rights reserved.
*
* SPDX-License-Identifier: BSD-3-Clause
*/
@@ -24,6 +24,8 @@
unsigned int cells, uint32_t *value);
int fdtw_read_string(const void *dtb, int node, const char *prop,
char *str, size_t size);
+int fdtw_read_uuid(const void *dtb, int node, const char *prop,
+ unsigned int length, uint8_t *uuid);
int fdtw_write_inplace_cells(void *dtb, int node, const char *prop,
unsigned int cells, void *value);
int fdtw_read_bytes(const void *dtb, int node, const char *prop,
diff --git a/include/common/uuid.h b/include/common/uuid.h
new file mode 100644
index 0000000..5651d0d
--- /dev/null
+++ b/include/common/uuid.h
@@ -0,0 +1,15 @@
+/*
+ * Copyright (c) 2021, Arm Limited and Contributors. All rights reserved.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#ifndef UUID_H
+#define UUID_H
+
+#define UUID_BYTES_LENGTH 16
+#define UUID_STRING_LENGTH 36
+
+int read_uuid(uint8_t *dest, char *uuid);
+
+#endif /* UUID_H */