sandbox: add sandbox sm uclass driver

This patch adds sandbox secure monitor driver.

Signed-off-by: Alexey Romanov <avromanov@salutedevices.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Link: https://lore.kernel.org/r/20230921081346.22157-3-avromanov@salutedevices.com
Signed-off-by: Neil Armstrong <neil.armstrong@linaro.org>

drivers/sm/Makefile

@@ -1,3 +1,4 @@
 # SPDX-License-Identifier: GPL-2.0-only
 
 obj-y += sm-uclass.o
+obj-$(CONFIG_SANDBOX) += sandbox-sm.o

drivers/sm/sandbox-sm.c

@@ -0,0 +1,76 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright (c) 2023 SberDevices, Inc.
+ *
+ * Author: Alexey Romanov <avromanov@salutedevices.com>
+ */
+
+#include <common.h>
+#include <sm.h>
+#include <sm-uclass.h>
+#include <sandbox-sm.h>
+#include <asm/ptrace.h>
+#include <dm/device.h>
+#include <linux/sizes.h>
+
+static u8 test_buffer[SZ_4K];
+
+static int sandbox_sm_call(struct udevice *dev, u32 cmd_index, s32 *smc_ret,
+			   struct pt_regs *args)
+{
+	if (cmd_index >= SANDBOX_SMC_CMD_COUNT)
+		return -EINVAL;
+
+	if (smc_ret)
+		*smc_ret = 0;
+
+	return 0;
+}
+
+static int sandbox_sm_call_read(struct udevice *dev, void *buffer, size_t size,
+				u32 cmd_index, struct pt_regs *args)
+{
+	if (cmd_index >= SANDBOX_SMC_CMD_COUNT || !buffer)
+		return -EINVAL;
+
+	if (size > sizeof(test_buffer))
+		return -EINVAL;
+
+	memcpy(buffer, test_buffer, size);
+
+	return size;
+}
+
+static int sandbox_sm_call_write(struct udevice *dev, void *buffer, size_t size,
+				 u32 cmd_index, struct pt_regs *args)
+{
+	if (cmd_index >= SANDBOX_SMC_CMD_COUNT || !buffer)
+		return -EINVAL;
+
+	if (size > sizeof(test_buffer))
+		return -EINVAL;
+
+	memcpy(test_buffer, buffer, size);
+
+	return size;
+}
+
+static const struct udevice_id sandbox_sm_ids[] = {
+	{
+		.compatible = "sandbox,sm",
+	},
+	{},
+};
+
+static const struct sm_ops sandbox_sm_ops = {
+	.sm_call = sandbox_sm_call,
+	.sm_call_read = sandbox_sm_call_read,
+	.sm_call_write = sandbox_sm_call_write,
+};
+
+U_BOOT_DRIVER(sm) = {
+	.name = "sm",
+	.id = UCLASS_SM,
+	.of_match = sandbox_sm_ids,
+	.ops = &sandbox_sm_ops,
+};

include/sandbox-sm.h

@@ -0,0 +1,18 @@
+/* SPDX-License-Identifier: GPL-2.0+ */
+/*
+ * Copyright (c) 2023 SberDevices, Inc.
+ *
+ * Author: Alexey Romanov <avromanov@salutedevices.com>
+ */
+
+#ifndef __SANDBOX_SM_H__
+#define __SANDBOX_SM_H__
+
+enum sandbox_smc_cmd {
+	SANDBOX_SMC_CMD_READ_MEM,
+	SANDBOX_SMC_CMD_WRITE_MEM,
+	SANDBOX_SMC_CMD_COMMON,
+	SANDBOX_SMC_CMD_COUNT,
+};
+
+#endif