crypto: ccp - fix command queuing to TEE ring buffer

Multiple threads or clients can submit a command to the TEE ring
buffer. This patch helps to synchronize command submission to the
ring.

One thread shall write a command to a TEE ring buffer entry only if:

 - Trusted OS has notified that the TEE command for the given entry
   has been processed and driver has copied the TEE response into
   client buffer.

 - The command entry is empty and can be written into.

After a command has been written to the TEE ring buffer, the global
wptr (mutex protected) shall be incremented for use by next client.

If PSP became unresponsive while processing TEE request from a
client, then further command submission to queue will be disabled.

Fixes: 33960acccfbd (crypto: ccp - add TEE support for Raven Ridge)
Reviewed-by: Devaraj Rangasamy <Devaraj.Rangasamy@amd.com>
Signed-off-by: Rijo Thomas <Rijo-john.Thomas@amd.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

1 files changed, 18 insertions, 2 deletions

diff --git a/drivers/crypto/ccp/tee-dev.h b/drivers/crypto/ccp/tee-dev.h
index f09960112115..49d26158b71e 100644
--- a/drivers/crypto/ccp/tee-dev.h
+++ b/drivers/crypto/ccp/tee-dev.h
@@ -1,6 +1,6 @@
 /* SPDX-License-Identifier: MIT */
 /*
- * Copyright 2019 Advanced Micro Devices, Inc.
+ * Copyright (C) 2019,2021 Advanced Micro Devices, Inc.
  *
  * Author: Rijo Thomas <Rijo-john.Thomas@amd.com>
  * Author: Devaraj Rangasamy <Devaraj.Rangasamy@amd.com>
@@ -18,7 +18,7 @@
 #include <linux/mutex.h>
 
 #define TEE_DEFAULT_TIMEOUT		10
-#define MAX_BUFFER_SIZE			992
+#define MAX_BUFFER_SIZE			988
 
 /**
  * enum tee_ring_cmd_id - TEE interface commands for ring buffer configuration
@@ -82,6 +82,20 @@ enum tee_cmd_state {
 };
 
 /**
+ * enum cmd_resp_state - TEE command's response status maintained by driver
+ * @CMD_RESPONSE_INVALID:      initial state when no command is written to ring
+ * @CMD_WAITING_FOR_RESPONSE:  driver waiting for response from TEE
+ * @CMD_RESPONSE_TIMEDOUT:     failed to get response from TEE
+ * @CMD_RESPONSE_COPIED:       driver has copied response from TEE
+ */
+enum cmd_resp_state {
+	CMD_RESPONSE_INVALID,
+	CMD_WAITING_FOR_RESPONSE,
+	CMD_RESPONSE_TIMEDOUT,
+	CMD_RESPONSE_COPIED,
+};
+
+/**
  * struct tee_ring_cmd - Structure of the command buffer in TEE ring
  * @cmd_id:      refers to &enum tee_cmd_id. Command id for the ring buffer
  *               interface
@@ -91,6 +105,7 @@ enum tee_cmd_state {
  * @pdata:       private data (currently unused)
  * @res1:        reserved region
  * @buf:         TEE command specific buffer
+ * @flag:	 refers to &enum cmd_resp_state
  */
 struct tee_ring_cmd {
 	u32 cmd_id;
@@ -100,6 +115,7 @@ struct tee_ring_cmd {
 	u64 pdata;
 	u32 res1[2];
 	u8 buf[MAX_BUFFER_SIZE];
+	u32 flag;
 
 	/* Total size: 1024 bytes */
 } __packed;