drivers: introduce Meson Secure Monitor driver

This patch adds an implementation of the Meson Secure Monitor
driver based on UCLASS_SM.

Signed-off-by: Alexey Romanov <avromanov@salutedevices.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Link: https://lore.kernel.org/r/20230921081346.22157-7-avromanov@salutedevices.com
Signed-off-by: Neil Armstrong <neil.armstrong@linaro.org>

include/meson/sm.h

@@ -0,0 +1,19 @@
+/* SPDX-License-Identifier: GPL-2.0+ */
+/*
+ * Copyright (c) 2023 SberDevices, Inc.
+ *
+ * Author: Alexey Romanov <avromanov@salutedevices.com>
+ */
+
+#ifndef __MESON_SM_CMD_H__
+#define __MESON_SM_CMD_H__
+
+enum meson_smc_cmd {
+	MESON_SMC_CMD_EFUSE_READ,  /* read efuse memory */
+	MESON_SMC_CMD_EFUSE_WRITE, /* write efuse memory */
+	MESON_SMC_CMD_CHIP_ID_GET, /* readh chip unique id */
+	MESON_SMC_CMD_PWRDM_SET,   /* do command at specified power domain */
+	MESON_SMC_CMD_COUNT,
+};
+
+#endif