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, 72 insertions, 0 deletions

diff --git a/include/sm-uclass.h b/include/sm-uclass.h
new file mode 100644
index 00000000000..c1144840440
--- /dev/null
+++ b/include/sm-uclass.h
@@ -0,0 +1,72 @@
+/* SPDX-License-Identifier: GPL-2.0+ */
+/*
+ * Copyright (c) 2023 SberDevices, Inc.
+ *
+ * Author: Alexey Romanov <avromanov@salutedevices.com>
+ */
+
+#ifndef __SM_UCLASS_H__
+#define __SM_UCLASS_H__
+
+#include <asm/types.h>
+#include <asm/ptrace.h>
+
+struct udevice;
+
+/**
+ * struct sm_ops - The functions that a SM driver must implement.
+ *
+ * @sm_call: Request a secure monitor call with specified command.
+ *
+ * @sm_call_read: Request a secure monitor call and retrieve data
+ * from secure-monitor (depends on specified command).
+ *
+ * @sm_call_write: Request a secure monitor call and send data
+ * to secure-monitor (depends on specified command).
+ *
+ * The individual methods are described more fully below.
+ */
+struct sm_ops {
+	/**
+	 * 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 *smc_ret,
+		       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);
+
+	/**
+	 * sm_call_read - retrieve data from secure-monitor
+	 *
+	 * @dev:	Pointer to UCLASS_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);
+};
+
+#endif /* __SM_UCLASS_H__ */