firmware: Add 64 bit MAC to shell prompt

This demonstrates that the readout of the 64 bit MAC address from the
STM32WL55 microcontroller works and is useful to recognize used devices.

5 files changed, 91 insertions, 1 deletions

diff --git a/firmware/CMakeLists.txt b/firmware/CMakeLists.txt
index 70b99c7..ad51a9d 100644
--- a/firmware/CMakeLists.txt
+++ b/firmware/CMakeLists.txt
@@ -2,4 +2,6 @@ cmake_minimum_required(VERSION 3.20.0)
 find_package(Zephyr REQUIRED HINTS $ENV{ZEPHYR_BASE})
 project(iot-core)
 
-target_sources(app PRIVATE src/main.c)
+target_sources(app PRIVATE
+	src/main.c
+	src/uid64.c)
diff --git a/firmware/boards/nucleo_wl55jc.overlay b/firmware/boards/nucleo_wl55jc.overlay
new file mode 100644
index 0000000..b04f810
--- /dev/null
+++ b/firmware/boards/nucleo_wl55jc.overlay
@@ -0,0 +1,7 @@
+/ {
+	soc {
+			uid64: uid64@1fff7580 {
+				reg = <0x1fff7580 0x8>;
+			};
+	};
+};
diff --git a/firmware/src/main.c b/firmware/src/main.c
index 7a1076c..e1c85c6 100644
--- a/firmware/src/main.c
+++ b/firmware/src/main.c
@@ -1,6 +1,38 @@
+#include <stdio.h>
+
 #include <zephyr/kernel.h>
+#include <zephyr/shell/shell.h>
+#include <zephyr/shell/shell_backend.h>
+
+#include "uid64.h"
+
+static uint64_t uid = 0;
+static char uid_str[UID64_STR_LEN];
+
+#define MAX_PROMPT_SIZE 80
+char prompt[MAX_PROMPT_SIZE];
+
+void init_uid64(void) {
+	uid = uid64_get();
+	uid64_to_string(uid, uid_str);
+}
+
+void init_shell_prompt(void) {
+	if (uid64_available()) {
+		snprintf(prompt, MAX_PROMPT_SIZE, "[iot-core %s] ", uid_str);
+	} else {
+		strncpy(prompt, "[iot-core without MAC] ", MAX_PROMPT_SIZE);
+	}
+	for (int i = 0; i < shell_backend_count_get(); i++) {
+		const struct shell *sh = shell_backend_get(i);
+		(void) shell_prompt_change(sh, (const char *)prompt);
+	}
+}
 
 int main(void)
 {
+	init_uid64();
+	init_shell_prompt();
+
 	return 0;
 }
diff --git a/firmware/src/uid64.c b/firmware/src/uid64.c
new file mode 100644
index 0000000..984b7fe
--- /dev/null
+++ b/firmware/src/uid64.c
@@ -0,0 +1,41 @@
+#include <stdio.h>
+
+#include <zephyr/devicetree.h>
+
+#include "uid64.h"
+
+#define UID64_NODE DT_NODELABEL(uid64)
+
+uint64_t uid64_get(void) {
+#if DT_NODE_EXISTS(UID64_NODE)
+		return *(volatile uint64_t *) DT_REG_ADDR(UID64_NODE);
+#else
+		return 0;
+#endif
+}
+
+void uid64_to_string(uint64_t uid, char *str) {
+	uint8_t *source = (uint8_t *)&uid + 7;
+	char *sink = str;
+
+	for (unsigned int i = 0; i < 8; i++) {
+		/* delimiter */
+		if (i > 0) {
+			*sink = ':';
+			sink++;
+		}
+
+		/* byte values */
+		snprintf(sink, 3, "%02x", *source);
+		source--;
+		sink += 2;
+	}
+}
+
+bool uid64_available(void) {
+#if DT_NODE_EXISTS(UID64_NODE)
+	return true;
+#else
+	return false;
+#endif
+}
diff --git a/firmware/src/uid64.h b/firmware/src/uid64.h
new file mode 100644
index 0000000..cd3fb13
--- /dev/null
+++ b/firmware/src/uid64.h
@@ -0,0 +1,8 @@
+#include <zephyr/devicetree.h>
+
+/* 2 chars per byte (hex), 1 char per ':' delimiter and one char for \0 */
+#define UID64_STR_LEN (8*2 + 7*1 + 1)
+
+uint64_t uid64_get(void);
+void uid64_to_string(uint64_t, char *str);
+bool uid64_available(void);