crypto: ccp - Check for CCP before registering crypto algs

If the ccp is built as a built-in module, then ccp-crypto (whether
built as a module or a built-in module) will be able to load and
it will register its crypto algorithms.  If the system does not have
a CCP this will result in -ENODEV being returned whenever a command
is attempted to be queued by the registered crypto algorithms.

Add an API, ccp_present(), that checks for the presence of a CCP
on the system.  The ccp-crypto module can use this to determine if it
should register it's crypto alogorithms.

Cc: stable@vger.kernel.org
Reported-by: Scot Doyle <lkml14@scotdoyle.com>
Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
Tested-by: Scot Doyle <lkml14@scotdoyle.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

1 files changed, 12 insertions, 0 deletions

diff --git a/include/linux/ccp.h b/include/linux/ccp.h
index ebcc9d146219..7f437036baa4 100644
--- a/include/linux/ccp.h
+++ b/include/linux/ccp.h
@@ -27,6 +27,13 @@ struct ccp_cmd;
         defined(CONFIG_CRYPTO_DEV_CCP_DD_MODULE)
 
 /**
+ * ccp_present - check if a CCP device is present
+ *
+ * Returns zero if a CCP device is present, -ENODEV otherwise.
+ */
+int ccp_present(void);
+
+/**
  * ccp_enqueue_cmd - queue an operation for processing by the CCP
  *
  * @cmd: ccp_cmd struct to be processed
@@ -53,6 +60,11 @@ int ccp_enqueue_cmd(struct ccp_cmd *cmd);
 
 #else /* CONFIG_CRYPTO_DEV_CCP_DD is not enabled */
 
+static inline int ccp_present(void)
+{
+        return -ENODEV;
+}
+
 static inline int ccp_enqueue_cmd(struct ccp_cmd *cmd)
 {
         return -ENODEV;