drivers/misc/optee: Add error conversion from errno to TEE errors

This commit simplifies sending errors back to OP-TEE and avoids
code duplication when handling errno values.

Signed-off-by: Theodore Karatapanis <tkaratapanis@census-labs.com>

drivers/misc/optee.c

@@ -1251,6 +1251,51 @@ int optee_convert_to_errno(uint32_t oterr)
     }
 }
 
+/****************************************************************************
+ * Name: optee_convert_from_errno
+ *
+ * Description:
+ *   Convert errno values to TEE errors.
+ *
+ * Parameters:
+ *   err - errno value (negative).
+ *
+ * Returned Values:
+ *   The converted TEE error code.
+ *
+ ****************************************************************************/
+
+uint32_t optee_convert_from_errno(int err)
+{
+  /* Make sure we handle negative errno values */
+
+  switch (-err)
+    {
+      case 0:
+        return TEE_SUCCESS;
+      case EACCES:
+        return TEE_ERROR_ACCESS_DENIED;
+      case EINVAL:
+        return TEE_ERROR_BAD_PARAMETERS;
+      case ENOTSUP:
+      case EOPNOTSUPP:
+        return TEE_ERROR_NOT_SUPPORTED;
+      case ENOMEM:
+        return TEE_ERROR_OUT_OF_MEMORY;
+      case EBUSY:
+        return TEE_ERROR_BUSY;
+      case ECOMM:
+      case EPROTO:
+        return TEE_ERROR_COMMUNICATION;
+      case ENOBUFS:
+        return TEE_ERROR_SHORT_BUFFER;
+      case ETIMEDOUT:
+        return TEE_ERROR_TIMEOUT;
+      default:
+        return TEE_ERROR_GENERIC;
+    }
+}
+
 /****************************************************************************
  * Name: optee_va_to_pa
  *

drivers/misc/optee.h

@@ -126,6 +126,7 @@ int optee_to_msg_param(FAR struct optee_priv_data *priv,
                        FAR const struct tee_ioctl_param *params);
 
 int optee_convert_to_errno(uint32_t oterr);
+uint32_t optee_convert_from_errno(int err);
 #undef EXTERN
 #if defined(__cplusplus)
 }

drivers/misc/optee_rpc.c

@@ -188,32 +188,16 @@ static void optee_rpc_cmd_shm_alloc(FAR struct optee_priv_data *priv,
         ret = optee_supplicant_alloc(priv, size, &shm);
         break;
 #else
-        arg->ret = TEE_ERROR_NOT_SUPPORTED;
+        ret = -ENOTSUP;
-        return;
 #endif
       case OPTEE_MSG_RPC_SHM_TYPE_KERNEL:
         ret = optee_shm_alloc(priv, NULL, size, TEE_SHM_ALLOC, &shm);
         break;
     }
 
-  if (ret == -ENOMEM)
+  arg->ret = optee_convert_from_errno(ret);
+  if (arg->ret != TEE_SUCCESS)
     {
-      arg->ret = TEE_ERROR_OUT_OF_MEMORY;
-      return;
-    }
-  else if (ret == -ECOMM)
-    {
-      arg->ret = TEE_ERROR_COMMUNICATION;
-      return;
-    }
-  else if (ret == -EINVAL)
-    {
-      arg->ret = TEE_ERROR_BAD_PARAMETERS;
-      return;
-    }
-  else if (ret != OK)
-    {
-      arg->ret = TEE_ERROR_GENERIC;
       return;
     }
 
@@ -233,8 +217,6 @@ static void optee_rpc_cmd_shm_alloc(FAR struct optee_priv_data *priv,
       arg->params[0].u.tmem.size = size;
       arg->params[0].u.tmem.shm_ref = (unsigned long)shm;
     }
-
-  arg->ret = TEE_SUCCESS;
 }
 
 /****************************************************************************

drivers/misc/optee_supplicant.c

@@ -558,34 +558,22 @@ void optee_supplicant_cmd(FAR struct optee_priv_data *priv,
       return;
     }
 
-  if (optee_from_msg_param(params, arg->num_params, arg->params))
+  if ((ret = optee_from_msg_param(params, arg->num_params, arg->params))
+      != 0)
     {
-      arg->ret = TEE_ERROR_BAD_PARAMETERS;
+      arg->ret = optee_convert_from_errno(ret);
       goto out;
     }
 
   arg->ret = optee_supplicant_request(arg->cmd, arg->num_params, params);
-
+  if (arg->ret != TEE_SUCCESS)
-  if ((ret = optee_to_msg_param(priv, arg->params, arg->num_params, params)))
     {
-      if (ret == -ENOMEM)
+      goto out;
-        {
-          arg->ret = TEE_ERROR_OUT_OF_MEMORY;
-        }
-      else if (ret == -EPROTO)
-        {
-          arg->ret = TEE_ERROR_COMMUNICATION;
-        }
-      else if (ret == -EINVAL)
-        {
-          arg->ret = TEE_ERROR_BAD_PARAMETERS;
-        }
-      else
-        {
-          arg->ret = TEE_ERROR_GENERIC;
-        }
     }
 
+  ret = optee_to_msg_param(priv, arg->params, arg->num_params, params);
+  arg->ret = optee_convert_from_errno(ret);
+
 out:
   kmm_free(params);
 }