crypto: ccp - Add support for fetching a nonce for dynamic boost control

Dynamic Boost Control is a feature offered on AMD client platforms that
allows software to request and set power or frequency limits.

Only software that has authenticated with the PSP can retrieve or set
these limits.

Create a character device and ioctl for fetching the nonce. This ioctl
supports optionally passing authentication information which will influence
how many calls the nonce is valid for.

Acked-by: Tom Lendacky <thomas.lendacky@amd.com>
Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

2 files changed, 68 insertions, 0 deletions

diff --git a/include/linux/psp-platform-access.h b/include/linux/psp-platform-access.h
index 75da8f5f7ad8..53b4a1df5180 100644
--- a/include/linux/psp-platform-access.h
+++ b/include/linux/psp-platform-access.h
@@ -8,6 +8,7 @@
 enum psp_platform_access_msg {
 	PSP_CMD_NONE = 0x0,
 	PSP_I2C_REQ_BUS_CMD = 0x64,
+	PSP_DYNAMIC_BOOST_GET_NONCE,
 };
 
 struct psp_req_buffer_hdr {
diff --git a/include/uapi/linux/psp-dbc.h b/include/uapi/linux/psp-dbc.h
new file mode 100644
index 000000000000..d032f78934e2
--- /dev/null
+++ b/include/uapi/linux/psp-dbc.h
@@ -0,0 +1,67 @@
+/* SPDX-License-Identifier: GPL-2.0-only WITH Linux-syscall-note */
+/*
+ * Userspace interface for AMD Dynamic Boost Control (DBC)
+ *
+ * Copyright (C) 2023 Advanced Micro Devices, Inc.
+ *
+ * Author: Mario Limonciello <mario.limonciello@amd.com>
+ */
+
+#ifndef __PSP_DBC_USER_H__
+#define __PSP_DBC_USER_H__
+
+#include <linux/types.h>
+
+/**
+ * DOC: AMD Dynamic Boost Control (DBC) interface
+ */
+
+#define DBC_NONCE_SIZE		16
+#define DBC_SIG_SIZE		32
+
+/**
+ * struct dbc_user_nonce - Nonce exchange structure (input/output).
+ * @auth_needed: Whether the PSP should authenticate this request (input).
+ *               0: no authentication, PSP will return single use nonce.
+ *               1: authentication: PSP will return multi-use nonce.
+ * @nonce:       8 byte value used for future authentication (output).
+ * @signature:   Optional 32 byte signature created by software using a
+ *               previous nonce (input).
+ */
+struct dbc_user_nonce {
+	__u32	auth_needed;
+	__u8	nonce[DBC_NONCE_SIZE];
+	__u8	signature[DBC_SIG_SIZE];
+} __packed;
+
+/**
+ * Dynamic Boost Control (DBC) IOC
+ *
+ * possible return codes for all DBC IOCTLs:
+ *  0:          success
+ *  -EINVAL:    invalid input
+ *  -E2BIG:     excess data passed
+ *  -EFAULT:    failed to copy to/from userspace
+ *  -EBUSY:     mailbox in recovery or in use
+ *  -ENODEV:    driver not bound with PSP device
+ *  -EACCES:    request isn't authorized
+ *  -EINVAL:    invalid parameter
+ *  -ETIMEDOUT: request timed out
+ *  -EAGAIN:    invalid request for state machine
+ *  -ENOENT:    not implemented
+ *  -ENFILE:    overflow
+ *  -EPERM:     invalid signature
+ *  -EIO:       unknown error
+ */
+#define DBC_IOC_TYPE	'D'
+
+/**
+ * DBCIOCNONCE - Fetch a nonce from the PSP for authenticating commands.
+ *               If a nonce is fetched without authentication it can only
+ *               be utilized for one command.
+ *               If a nonce is fetched with authentication it can be used
+ *               for multiple requests.
+ */
+#define DBCIOCNONCE	_IOWR(DBC_IOC_TYPE, 0x1, struct dbc_user_nonce)
+
+#endif /* __PSP_DBC_USER_H__ */