rpmsg: Introduce __rpmsg{16|32|64} types

Introduce __rpmsg{16|32|64} types along with byte order conversion
functions based on an rpmsg_device operation as a foundation to
make RPMSG modular and transport agnostic.

Tested-by: Guennadi Liakhovetski <guennadi.liakhovetski@linux.intel.com>
Suggested-by: Guennadi Liakhovetski <guennadi.liakhovetski@linux.intel.com>
Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Reviewed-by: Arnaud Pouliquen <arnaud.pouliquen@st.com>
Reviewed-by: Guennadi Liakhovetski <guennadi.liakhovetski@linux.intel.com>
Link: https://lore.kernel.org/r/20201120214245.172963-2-mathieu.poirier@linaro.org
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>

include/linux/rpmsg.h

@@ -17,6 +17,7 @@
 #include <linux/kref.h>
 #include <linux/mutex.h>
 #include <linux/poll.h>
+#include <linux/rpmsg/byteorder.h>
 
 #define RPMSG_ADDR_ANY		0xFFFFFFFF
 
@@ -46,6 +47,7 @@ struct rpmsg_channel_info {
  * @dst: destination address
  * @ept: the rpmsg endpoint of this channel
  * @announce: if set, rpmsg will announce the creation/removal of this channel
+ * @little_endian: True if transport is using little endian byte representation
  */
 struct rpmsg_device {
 	struct device dev;
@@ -55,6 +57,7 @@ struct rpmsg_device {
 	u32 dst;
 	struct rpmsg_endpoint *ept;
 	bool announce;
+	bool little_endian;
 
 	const struct rpmsg_device_ops *ops;
 };
@@ -111,6 +114,54 @@ struct rpmsg_driver {
 	int (*callback)(struct rpmsg_device *, void *, int, void *, u32);
 };
 
+static inline u16 rpmsg16_to_cpu(struct rpmsg_device *rpdev, __rpmsg16 val)
+{
+	if (!rpdev)
+		return __rpmsg16_to_cpu(rpmsg_is_little_endian(), val);
+	else
+		return __rpmsg16_to_cpu(rpdev->little_endian, val);
+}
+
+static inline __rpmsg16 cpu_to_rpmsg16(struct rpmsg_device *rpdev, u16 val)
+{
+	if (!rpdev)
+		return __cpu_to_rpmsg16(rpmsg_is_little_endian(), val);
+	else
+		return __cpu_to_rpmsg16(rpdev->little_endian, val);
+}
+
+static inline u32 rpmsg32_to_cpu(struct rpmsg_device *rpdev, __rpmsg32 val)
+{
+	if (!rpdev)
+		return __rpmsg32_to_cpu(rpmsg_is_little_endian(), val);
+	else
+		return __rpmsg32_to_cpu(rpdev->little_endian, val);
+}
+
+static inline __rpmsg32 cpu_to_rpmsg32(struct rpmsg_device *rpdev, u32 val)
+{
+	if (!rpdev)
+		return __cpu_to_rpmsg32(rpmsg_is_little_endian(), val);
+	else
+		return __cpu_to_rpmsg32(rpdev->little_endian, val);
+}
+
+static inline u64 rpmsg64_to_cpu(struct rpmsg_device *rpdev, __rpmsg64 val)
+{
+	if (!rpdev)
+		return __rpmsg64_to_cpu(rpmsg_is_little_endian(), val);
+	else
+		return __rpmsg64_to_cpu(rpdev->little_endian, val);
+}
+
+static inline __rpmsg64 cpu_to_rpmsg64(struct rpmsg_device *rpdev, u64 val)
+{
+	if (!rpdev)
+		return __cpu_to_rpmsg64(rpmsg_is_little_endian(), val);
+	else
+		return __cpu_to_rpmsg64(rpdev->little_endian, val);
+}
+
 #if IS_ENABLED(CONFIG_RPMSG)
 
 int register_rpmsg_device(struct rpmsg_device *dev);

include/linux/rpmsg/byteorder.h

@@ -0,0 +1,67 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Follows implementation found in linux/virtio_byteorder.h
+ */
+#ifndef _LINUX_RPMSG_BYTEORDER_H
+#define _LINUX_RPMSG_BYTEORDER_H
+#include <linux/types.h>
+#include <uapi/linux/rpmsg_types.h>
+
+static inline bool rpmsg_is_little_endian(void)
+{
+#ifdef __LITTLE_ENDIAN
+	return true;
+#else
+	return false;
+#endif
+}
+
+static inline u16 __rpmsg16_to_cpu(bool little_endian, __rpmsg16 val)
+{
+	if (little_endian)
+		return le16_to_cpu((__force __le16)val);
+	else
+		return be16_to_cpu((__force __be16)val);
+}
+
+static inline __rpmsg16 __cpu_to_rpmsg16(bool little_endian, u16 val)
+{
+	if (little_endian)
+		return (__force __rpmsg16)cpu_to_le16(val);
+	else
+		return (__force __rpmsg16)cpu_to_be16(val);
+}
+
+static inline u32 __rpmsg32_to_cpu(bool little_endian, __rpmsg32 val)
+{
+	if (little_endian)
+		return le32_to_cpu((__force __le32)val);
+	else
+		return be32_to_cpu((__force __be32)val);
+}
+
+static inline __rpmsg32 __cpu_to_rpmsg32(bool little_endian, u32 val)
+{
+	if (little_endian)
+		return (__force __rpmsg32)cpu_to_le32(val);
+	else
+		return (__force __rpmsg32)cpu_to_be32(val);
+}
+
+static inline u64 __rpmsg64_to_cpu(bool little_endian, __rpmsg64 val)
+{
+	if (little_endian)
+		return le64_to_cpu((__force __le64)val);
+	else
+		return be64_to_cpu((__force __be64)val);
+}
+
+static inline __rpmsg64 __cpu_to_rpmsg64(bool little_endian, u64 val)
+{
+	if (little_endian)
+		return (__force __rpmsg64)cpu_to_le64(val);
+	else
+		return (__force __rpmsg64)cpu_to_be64(val);
+}
+
+#endif /* _LINUX_RPMSG_BYTEORDER_H */

include/uapi/linux/rpmsg_types.h

@@ -0,0 +1,11 @@
+/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
+#ifndef _UAPI_LINUX_RPMSG_TYPES_H
+#define _UAPI_LINUX_RPMSG_TYPES_H
+
+#include <linux/types.h>
+
+typedef __u16 __bitwise __rpmsg16;
+typedef __u32 __bitwise __rpmsg32;
+typedef __u64 __bitwise __rpmsg64;
+
+#endif /* _UAPI_LINUX_RPMSG_TYPES_H */