drivers: hwinfo: native: report reset cause

Support reporting the reset cause for native_sim. The default is to
report POR (Power-On Reset). If CONFIG_NATIVE_SIM_REBOOT was enabled and
the system is rebooted using sys_reboot(), the reset cause is set to
SOFTWARE.

Signed-off-by: Tim Pambor <[email protected]>

Author: tpambor

boards/native/native_sim/reboot_bottom.c

@@ -13,6 +13,7 @@
 #include <nsi_tasks.h>
 #include <nsi_tracing.h>
 #include <nsi_cmdline.h>
+#include <nsi_host_trampolines.h>
 
 static const char module[] = "native_sim_reboot";
 
@@ -63,6 +64,9 @@ void maybe_reboot(void)
 		nsi_exit(1);
 	}
 
+	/* Let's set an environment variable which the native_sim hw_info driver may check */
+	(void)nsi_host_setenv("NATIVE_SIM_RESET_CAUSE", "SOFTWARE", 1);
+
 	nsi_print_warning("%s: Restarting process.\n", module);
 
 	(void)execv("/proc/self/exe", argv);

drivers/hwinfo/hwinfo_native.c

@@ -4,6 +4,7 @@
  */
 
 #include <cmdline.h>
+#include <nsi_host_trampolines.h>
 #include <posix_native_task.h>
 #include <string.h>
 #include <zephyr/drivers/hwinfo.h>
@@ -13,6 +14,7 @@
 
 static uint32_t native_hwinfo_device_id;
 static bool native_hwinfo_device_id_set;
+static uint32_t native_hwinfo_reset_cause;
 
 ssize_t z_impl_hwinfo_get_device_id(uint8_t *buffer, size_t length)
 {
@@ -26,6 +28,27 @@ ssize_t z_impl_hwinfo_get_device_id(uint8_t *buffer, size_t length)
 	return length;
 }
 
+int z_impl_hwinfo_get_reset_cause(uint32_t *cause)
+{
+	*cause = native_hwinfo_reset_cause;
+
+	return 0;
+}
+
+int z_impl_hwinfo_clear_reset_cause(void)
+{
+	native_hwinfo_reset_cause = 0;
+
+	return 0;
+}
+
+int z_impl_hwinfo_get_supported_reset_cause(uint32_t *supported)
+{
+	*supported = RESET_POR | RESET_SOFTWARE;
+
+	return 0;
+}
+
 static void native_hwinfo_gethostid(void)
 {
 	if (!native_hwinfo_device_id_set) {
@@ -59,5 +82,30 @@ static void native_hwinfo_add_options(void)
 	native_add_command_line_opts(native_hwinfo_options);
 }
 
+static void native_hwinfo_get_reset_cause(void)
+{
+	/* If CONFIG_NATIVE_SIM_REBOOT was set, and a reboot was triggered, this
+	 * environment variable would be set. Otherwise it is not expected to
+	 * exist. Note this environment variable is not an stable API of any kind
+	 */
+	const char *cause = nsi_host_getenv("NATIVE_SIM_RESET_CAUSE");
+
+	if (!cause) {
+		/* Default to POR if not set */
+		native_hwinfo_reset_cause = RESET_POR;
+		return;
+	}
+
+	if (strcmp(cause, "SOFTWARE") == 0) {
+		native_hwinfo_reset_cause = RESET_SOFTWARE;
+	} else {
+		posix_print_warning("NATIVE_SIM_RESET_CAUSE (%s) set to an unknown reset cause, "
+				    "defaulting to POR\n",
+				    cause);
+		native_hwinfo_reset_cause = RESET_POR;
+	}
+}
+
 NATIVE_TASK(native_hwinfo_add_options, PRE_BOOT_1, 10);
 NATIVE_TASK(native_hwinfo_gethostid, PRE_BOOT_2, 10);
+NATIVE_TASK(native_hwinfo_get_reset_cause, PRE_BOOT_2, 10);