Add a mailbox driver framework/uclass

A mailbox is a hardware mechanism for transferring small message and/or
notifications between the CPU on which U-Boot runs and some other device
such as an auxilliary CPU running firmware or a hardware module.

This patch defines a standard API that connects mailbox clients to mailbox
providers (drivers). Initially, DT is the only supported method for
connecting the two.

The DT binding specification (mailbox.txt) was taken from Linux kernel
v4.5's Documentation/devicetree/bindings/mailbox/mailbox.txt.

Signed-off-by: Stephen Warren <swarren@nvidia.com>
Acked-by: Simon Glass <sjg@chromium.org>

1 files changed, 83 insertions, 0 deletions

diff --git a/include/mailbox_uclass.h b/include/mailbox_uclass.h
new file mode 100644
index 0000000000..6a2994c34c
--- /dev/null
+++ b/include/mailbox_uclass.h
@@ -0,0 +1,83 @@
+/*
+ * Copyright (c) 2016, NVIDIA CORPORATION.
+ *
+ * SPDX-License-Identifier: GPL-2.0
+ */
+
+#ifndef _MAILBOX_UCLASS_H
+#define _MAILBOX_UCLASS_H
+
+/* See mailbox_client.h for background documentation. */
+
+#include <mailbox_client.h>
+
+struct udevice;
+
+/**
+ * struct mbox_ops - The functions that a mailbox driver must implement.
+ */
+struct mbox_ops {
+	/**
+	 * of_xlate - Translate a client's device-tree (OF) mailbox specifier.
+	 *
+	 * The mailbox core calls this function as the first step in
+	 * implementing a client's mbox_get_by_*() call.
+	 *
+	 * If this function pointer is set to NULL, the mailbox core will use
+	 * a default implementation, which assumes #mbox-cells = <1>, and that
+	 * the DT cell contains a simple integer channel ID.
+	 *
+	 * At present, the mailbox API solely supports device-tree. If this
+	 * changes, other xxx_xlate() functions may be added to support those
+	 * other mechanisms.
+	 *
+	 * @chan:	The channel to hold the translation result.
+	 * @args:	The mailbox specifier values from device tree.
+	 * @return 0 if OK, or a negative error code.
+	 */
+	int (*of_xlate)(struct mbox_chan *chan,
+			struct fdtdec_phandle_args *args);
+	/**
+	 * request - Request a translated channel.
+	 *
+	 * The mailbox core calls this function as the second step in
+	 * implementing a client's mbox_get_by_*() call, following a successful
+	 * xxx_xlate() call.
+	 *
+	 * @chan:	The channel to request; this has been filled in by a
+	 *		previoux xxx_xlate() function call.
+	 * @return 0 if OK, or a negative error code.
+	 */
+	int (*request)(struct mbox_chan *chan);
+	/**
+	 * free - Free a previously requested channel.
+	 *
+	 * This is the implementation of the client mbox_free() API.
+	 *
+	 * @chan:	The channel to free.
+	 * @return 0 if OK, or a negative error code.
+	 */
+	int (*free)(struct mbox_chan *chan);
+	/**
+	* send - Send a message over a mailbox channel
+	*
+	* @chan:	The channel to send to the message to.
+	* @data:	A pointer to the message to send.
+	* @return 0 if OK, or a negative error code.
+	*/
+	int (*send)(struct mbox_chan *chan, const void *data);
+	/**
+	* recv - Receive any available message from the channel.
+	*
+	* This function does not block. If not message is immediately
+	* available, the function should return an error.
+	*
+	* @chan:	The channel to receive to the message from.
+	* @data:	A pointer to the buffer to hold the received message.
+	* @return 0 if OK, -ENODATA if no message was available, or a negative
+	* error code.
+	*/
+	int (*recv)(struct mbox_chan *chan, void *data);
+};
+
+#endif