mailbox: ZynqMP IPI mailbox controller

This patch is to introduce ZynqMP IPI mailbox controller driver
to use the ZynqMP IPI block as mailboxes.

Signed-off-by: Wendy Liang <wendy.liang@xilinx.com>
Signed-off-by: Jassi Brar <jaswinder.singh@linaro.org>

include/linux/mailbox/zynqmp-ipi-message.h

@@ -0,0 +1,20 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+#ifndef _LINUX_ZYNQMP_IPI_MESSAGE_H_
+#define _LINUX_ZYNQMP_IPI_MESSAGE_H_
+
+/**
+ * struct zynqmp_ipi_message - ZynqMP IPI message structure
+ * @len:  Length of message
+ * @data: message payload
+ *
+ * This is the structure for data used in mbox_send_message
+ * the maximum length of data buffer is fixed to 12 bytes.
+ * Client is supposed to be aware of this.
+ */
+struct zynqmp_ipi_message {
+	size_t len;
+	u8 data[0];
+};
+
+#endif /* _LINUX_ZYNQMP_IPI_MESSAGE_H_ */