ARM: 6415/1: ux500: DB5500 mailbox driver

This is a driver for the mailboxes used to communicate with the
DB5500 modem portions.
Signed-off-by: Stefan Nilsson XK <stefan.xk.nilsson@stericsson.com>
Signed-off-by: Linus Walleij <linus.walleij@stericsson.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

arch/arm/mach-ux500/include/mach/mbox.h

+/*
+ * Copyright (C) ST-Ericsson SA 2010
+ * Author: Stefan Nilsson <stefan.xk.nilsson@stericsson.com> for ST-Ericsson.
+ * Author: Martin Persson <martin.persson@stericsson.com> for ST-Ericsson.
+ * License terms: GNU General Public License (GPL), version 2.
+ */
+
+#ifndef __INC_STE_MBOX_H
+#define __INC_STE_MBOX_H
+
+#define MBOX_BUF_SIZE 16
+#define MBOX_NAME_SIZE 8
+
+/**
+  * mbox_recv_cb_t - Definition of the mailbox callback.
+  * @mbox_msg:	The mailbox message.
+  * @priv:	The clients private data as specified in the call to mbox_setup.
+  *
+  * This function will be called upon reception of new mailbox messages.
+  */
+typedef void mbox_recv_cb_t (u32 mbox_msg, void *priv);
+
+/**
+  * struct mbox - Mailbox instance struct
+  * @list:		Linked list head.
+  * @pdev:		Pointer to device struct.
+  * @cb:		Callback function. Will be called
+  *			when new data is received.
+  * @client_data:	Clients private data. Will be sent back
+  *			in the callback function.
+  * @virtbase_peer:	Virtual address for outgoing mailbox.
+  * @virtbase_local:	Virtual address for incoming mailbox.
+  * @buffer:		Then internal queue for outgoing messages.
+  * @name:		Name of this mailbox.
+  * @buffer_available:	Completion variable to achieve "blocking send".
+  *			This variable will be signaled when there is
+  *			internal buffer space available.
+  * @client_blocked:	To keep track if any client is currently
+  *			blocked.
+  * @lock:		Spinlock to protect this mailbox instance.
+  * @write_index:	Index in internal buffer to write to.
+  * @read_index:	Index in internal buffer to read from.
+  * @allocated:		Indicates whether this particular mailbox
+  *			id has been allocated by someone.
+  */
+struct mbox {
+	struct list_head list;
+	struct platform_device *pdev;
+	mbox_recv_cb_t *cb;
+	void *client_data;
+	void __iomem *virtbase_peer;
+	void __iomem *virtbase_local;
+	u32 buffer[MBOX_BUF_SIZE];
+	char name[MBOX_NAME_SIZE];
+	struct completion buffer_available;
+	u8 client_blocked;
+	spinlock_t lock;
+	u8 write_index;
+	u8 read_index;
+	bool allocated;
+};
+
+/**
+  * mbox_setup - Set up a mailbox and return its instance.
+  * @mbox_id:	The ID number of the mailbox. 0 or 1 for modem CPU,
+  *		2 for modem DSP.
+  * @mbox_cb:	Pointer to the callback function to be called when a new message
+  *		is received.
+  * @priv:	Client user data which will be returned in the callback.
+  *
+  * Returns a mailbox instance to be specified in subsequent calls to mbox_send.
+  */
+struct mbox *mbox_setup(u8 mbox_id, mbox_recv_cb_t *mbox_cb, void *priv);
+
+/**
+  * mbox_send - Send a mailbox message.
+  * @mbox:	Mailbox instance (returned by mbox_setup)
+  * @mbox_msg:	The mailbox message to send.
+  * @block:	Specifies whether this call will block until send is possible,
+  *		or return an error if the mailbox buffer is full.
+  *
+  * Returns 0 on success or a negative error code on error. -ENOMEM indicates
+  * that the internal buffer is full and you have to try again later (or
+  * specify "block" in order to block until send is possible).
+  */
+int mbox_send(struct mbox *mbox, u32 mbox_msg, bool block);
+
+#endif /*INC_STE_MBOX_H*/