drivers: introduce Secure Monitor uclass

At the moment, we don't have a common API for working with
SM, only the smc_call() function. This approach is not generic
and difficult to configure and maintain.

This patch adds UCLASS_SM with the generic API:

- sm_call()
- sm_call_write()
- sm_call_read()

These functions operate with struct pt_regs, which describes
Secure Monitor arguments.

Signed-off-by: Alexey Romanov <avromanov@salutedevices.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Link: https://lore.kernel.org/r/20230921081346.22157-2-avromanov@salutedevices.com
Signed-off-by: Neil Armstrong <neil.armstrong@linaro.org>

1 files changed, 67 insertions, 0 deletions

diff --git a/include/sm.h b/include/sm.h
new file mode 100644
index 00000000000..afa9c89055e
--- /dev/null
+++ b/include/sm.h
@@ -0,0 +1,67 @@
+/* SPDX-License-Identifier: GPL-2.0+ */
+/*
+ * Copyright (c) 2023 SberDevices, Inc.
+ *
+ * Author: Alexey Romanov <avromanov@salutedevices.ru>
+ */
+
+#ifndef __SM_H__
+#define __SM_H__
+
+/*
+ * NOTE: UCLASS_SM is designed with the idea that
+ * each driver should convert @cmd to some raw
+ * value, which is known only for driver, and set this
+ * value to the first element of the @args->regs array.
+ * Therefore, it is necessary to pass the remaining
+ * arguments starting at index = 1. Anyway, driver
+ * implementation may vary, so, please, check the specific
+ * implementation of the driver you are using.
+ */
+
+#include <asm/types.h>
+#include <asm/ptrace.h>
+
+struct udevice;
+
+/**
+ * sm_call - generic SMC call to the secure-monitor
+ *
+ * @dev:	Pointer to UCLASS_SM device
+ * @cmd_index:	Index of the SMC function ID
+ * @smc_ret:	Returned value from secure world
+ * @args:	SMC arguments
+ *
+ * @return:	0 on success, a negative value on error
+ */
+int sm_call(struct udevice *dev, u32 cmd, s32 *ret, struct pt_regs *args);
+
+/**
+ * sm_call_read - retrieve data from secure-monitor
+ *
+ * @dev:	Pointer to UCLASS_MESON_SM device
+ * @buffer:	Buffer to store the retrieved data
+ * @size:	Size of the buffer
+ * @cmd:	Index of the SMC function ID
+ * @args:	SMC arguments
+ *
+ * @return:	size of read data on success, a negative value on error
+ */
+int sm_call_read(struct udevice *dev, void *buffer, size_t size,
+		 u32 cmd, struct pt_regs *args);
+
+/**
+ * sm_call_write - send data to secure-monitor
+ *
+ * @dev:	Pointer to UCLASS_SM device
+ * @buffer:	Buffer containing data to send
+ * @size:	Size of the buffer
+ * @cmd:	Index of the SMC function ID
+ * @args:	SMC arguments
+ *
+ * @return:	size of sent data on success, a negative value on error
+ */
+int sm_call_write(struct udevice *dev, void *buffer, size_t size,
+		  u32 cmd, struct pt_regs *args);
+
+#endif /* __SM_H__ */