Merge branch 'mailbox-for-linus' of git://git.linaro.org/landing-teams/working/fujitsu/integration

Pull mailbox framework from Jassi Brar:
 "A framework for Mailbox controllers and clients have been cooking for
  more than a year now.

  Everybody in the CC list had been copied on patchset revisions and
  most of them have made sounds of approval, though just one concrete
  Reviewed-by.  The patchset has also been in linux-next for a couple of
  weeks now and no conflict has been reported.  The framework has the
  backing of at least 5 platforms, though I can't say if/when they
  upstream their drivers (some businesses have 'changed')"

(Further acked-by by Arnd Bergmann and Suman Anna in the pull request
thread)

* 'mailbox-for-linus' of git://git.linaro.org/landing-teams/working/fujitsu/integration:
  dt: mailbox: add generic bindings
  doc: add documentation for mailbox framework
  mailbox: Introduce framework for mailbox
  mailbox: rename pl320-ipc specific mailbox.h

Documentation/devicetree/bindings/mailbox/mailbox.txt

+* Generic Mailbox Controller and client driver bindings
+
+Generic binding to provide a way for Mailbox controller drivers to
+assign appropriate mailbox channel to client drivers.
+
+* Mailbox Controller
+
+Required property:
+- #mbox-cells: Must be at least 1. Number of cells in a mailbox
+		specifier.
+
+Example:
+	mailbox: mailbox {
+		...
+		#mbox-cells = <1>;
+	};
+
+
+* Mailbox Client
+
+Required property:
+- mboxes: List of phandle and mailbox channel specifiers.
+
+Optional property:
+- mbox-names: List of identifier strings for each mailbox channel
+		required by the client. The use of this property
+		is discouraged in favor of using index in list of
+		'mboxes' while requesting a mailbox. Instead the
+		platforms may define channel indices, in DT headers,
+		to something legible.
+
+Example:
+	pwr_cntrl: power {
+		...
+		mbox-names = "pwr-ctrl", "rpc";
+		mboxes = <&mailbox 0
+			&mailbox 1>;
+	};

Documentation/mailbox.txt

+		The Common Mailbox Framework
+		Jassi Brar <jaswinder.singh@linaro.org>
+
+ This document aims to help developers write client and controller
+drivers for the API. But before we start, let us note that the
+client (especially) and controller drivers are likely going to be
+very platform specific because the remote firmware is likely to be
+proprietary and implement non-standard protocol. So even if two
+platforms employ, say, PL320 controller, the client drivers can't
+be shared across them. Even the PL320 driver might need to accommodate
+some platform specific quirks. So the API is meant mainly to avoid
+similar copies of code written for each platform. Having said that,
+nothing prevents the remote f/w to also be Linux based and use the
+same api there. However none of that helps us locally because we only
+ever deal at client's protocol level.
+ Some of the choices made during implementation are the result of this
+peculiarity of this "common" framework.
+
+
+
+	Part 1 - Controller Driver (See include/linux/mailbox_controller.h)
+
+ Allocate mbox_controller and the array of mbox_chan.
+Populate mbox_chan_ops, except peek_data() all are mandatory.
+The controller driver might know a message has been consumed
+by the remote by getting an IRQ or polling some hardware flag
+or it can never know (the client knows by way of the protocol).
+The method in order of preference is IRQ -> Poll -> None, which
+the controller driver should set via 'txdone_irq' or 'txdone_poll'
+or neither.
+
+
+	Part 2 - Client Driver (See include/linux/mailbox_client.h)
+
+ The client might want to operate in blocking mode (synchronously
+send a message through before returning) or non-blocking/async mode (submit
+a message and a callback function to the API and return immediately).
+
+
+struct demo_client {
+	struct mbox_client cl;
+	struct mbox_chan *mbox;
+	struct completion c;
+	bool async;
+	/* ... */
+};
+
+/*
+ * This is the handler for data received from remote. The behaviour is purely
+ * dependent upon the protocol. This is just an example.
+ */
+static void message_from_remote(struct mbox_client *cl, void *mssg)
+{
+	struct demo_client *dc = container_of(mbox_client,
+						struct demo_client, cl);
+	if (dc->aysnc) {
+		if (is_an_ack(mssg)) {
+			/* An ACK to our last sample sent */
+			return; /* Or do something else here */
+		} else { /* A new message from remote */
+			queue_req(mssg);
+		}
+	} else {
+		/* Remote f/w sends only ACK packets on this channel */
+		return;
+	}
+}
+
+static void sample_sent(struct mbox_client *cl, void *mssg, int r)
+{
+	struct demo_client *dc = container_of(mbox_client,
+						struct demo_client, cl);
+	complete(&dc->c);
+}
+
+static void client_demo(struct platform_device *pdev)
+{
+	struct demo_client *dc_sync, *dc_async;
+	/* The controller already knows async_pkt and sync_pkt */
+	struct async_pkt ap;
+	struct sync_pkt sp;
+
+	dc_sync = kzalloc(sizeof(*dc_sync), GFP_KERNEL);
+	dc_async = kzalloc(sizeof(*dc_async), GFP_KERNEL);
+
+	/* Populate non-blocking mode client */
+	dc_async->cl.dev = &pdev->dev;
+	dc_async->cl.rx_callback = message_from_remote;
+	dc_async->cl.tx_done = sample_sent;
+	dc_async->cl.tx_block = false;
+	dc_async->cl.tx_tout = 0; /* doesn't matter here */
+	dc_async->cl.knows_txdone = false; /* depending upon protocol */
+	dc_async->async = true;
+	init_completion(&dc_async->c);
+
+	/* Populate blocking mode client */
+	dc_sync->cl.dev = &pdev->dev;
+	dc_sync->cl.rx_callback = message_from_remote;
+	dc_sync->cl.tx_done = NULL; /* operate in blocking mode */
+	dc_sync->cl.tx_block = true;
+	dc_sync->cl.tx_tout = 500; /* by half a second */
+	dc_sync->cl.knows_txdone = false; /* depending upon protocol */
+	dc_sync->async = false;
+
+	/* ASync mailbox is listed second in 'mboxes' property */
+	dc_async->mbox = mbox_request_channel(&dc_async->cl, 1);
+	/* Populate data packet */
+	/* ap.xxx = 123; etc */
+	/* Send async message to remote */
+	mbox_send_message(dc_async->mbox, &ap);
+
+	/* Sync mailbox is listed first in 'mboxes' property */
+	dc_sync->mbox = mbox_request_channel(&dc_sync->cl, 0);
+	/* Populate data packet */
+	/* sp.abc = 123; etc */
+	/* Send message to remote in blocking mode */
+	mbox_send_message(dc_sync->mbox, &sp);
+	/* At this point 'sp' has been sent */
+
+	/* Now wait for async chan to be done */
+	wait_for_completion(&dc_async->c);
+}

MAINTAINERS

@@ -5834,6 +5834,14 @@ S:	Maintained
 F:	drivers/net/macvlan.c
 F:	include/linux/if_macvlan.h
 
+MAILBOX API
+M:	Jassi Brar <jassisinghbrar@gmail.com>
+L:	linux-kernel@vger.kernel.org
+S:	Maintained
+F:	drivers/mailbox/
+F:	include/linux/mailbox_client.h
+F:	include/linux/mailbox_controller.h
+
 MAN-PAGES: MANUAL PAGES FOR LINUX -- Sections 2, 3, 4, 5, and 7
 M:	Michael Kerrisk <mtk.manpages@gmail.com>
 W:	http://www.kernel.org/doc/man-pages

arch/arm/mach-highbank/highbank.c

@@ -20,7 +20,7 @@
 #include <linux/input.h>
 #include <linux/io.h>
 #include <linux/irqchip.h>
-#include <linux/mailbox.h>
+#include <linux/pl320-ipc.h>
 #include <linux/of.h>
 #include <linux/of_irq.h>
 #include <linux/of_platform.h>

drivers/cpufreq/highbank-cpufreq.c

@@ -19,7 +19,7 @@
 #include <linux/cpu.h>
 #include <linux/err.h>
 #include <linux/of.h>
-#include <linux/mailbox.h>
+#include <linux/pl320-ipc.h>
 #include <linux/platform_device.h>
 
 #define HB_CPUFREQ_CHANGE_NOTE	0x80000001

drivers/mailbox/Makefile

+# Generic MAILBOX API
+
+obj-$(CONFIG_MAILBOX)		+= mailbox.o
+
 obj-$(CONFIG_PL320_MBOX)	+= pl320-ipc.o
 
 obj-$(CONFIG_OMAP2PLUS_MBOX)	+= omap-mailbox.o

drivers/mailbox/pl320-ipc.c

@@ -26,7 +26,7 @@
 #include <linux/device.h>
 #include <linux/amba/bus.h>
 
-#include <linux/mailbox.h>
+#include <linux/pl320-ipc.h>
 
 #define IPCMxSOURCE(m)		((m) * 0x40)
 #define IPCMxDSET(m)		(((m) * 0x40) + 0x004)

include/linux/mailbox_client.h

+/*
+ * Copyright (C) 2013-2014 Linaro Ltd.
+ * Author: Jassi Brar <jassisinghbrar@gmail.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#ifndef __MAILBOX_CLIENT_H
+#define __MAILBOX_CLIENT_H
+
+#include <linux/of.h>
+#include <linux/device.h>
+
+struct mbox_chan;
+
+/**
+ * struct mbox_client - User of a mailbox
+ * @dev:		The client device
+ * @tx_block:		If the mbox_send_message should block until data is
+ *			transmitted.
+ * @tx_tout:		Max block period in ms before TX is assumed failure
+ * @knows_txdone:	If the client could run the TX state machine. Usually
+ *			if the client receives some ACK packet for transmission.
+ *			Unused if the controller already has TX_Done/RTR IRQ.
+ * @rx_callback:	Atomic callback to provide client the data received
+ * @tx_done:		Atomic callback to tell client of data transmission
+ */
+struct mbox_client {
+	struct device *dev;
+	bool tx_block;
+	unsigned long tx_tout;
+	bool knows_txdone;
+
+	void (*rx_callback)(struct mbox_client *cl, void *mssg);
+	void (*tx_done)(struct mbox_client *cl, void *mssg, int r);
+};
+
+struct mbox_chan *mbox_request_channel(struct mbox_client *cl, int index);
+int mbox_send_message(struct mbox_chan *chan, void *mssg);
+void mbox_client_txdone(struct mbox_chan *chan, int r); /* atomic */
+bool mbox_client_peek_data(struct mbox_chan *chan); /* atomic */
+void mbox_free_channel(struct mbox_chan *chan); /* may sleep */
+
+#endif /* __MAILBOX_CLIENT_H */

include/linux/mailbox_controller.h

+/*
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#ifndef __MAILBOX_CONTROLLER_H
+#define __MAILBOX_CONTROLLER_H
+
+#include <linux/of.h>
+#include <linux/types.h>
+#include <linux/timer.h>
+#include <linux/device.h>
+#include <linux/completion.h>
+
+struct mbox_chan;
+
+/**
+ * struct mbox_chan_ops - methods to control mailbox channels
+ * @send_data:	The API asks the MBOX controller driver, in atomic
+ *		context try to transmit a message on the bus. Returns 0 if
+ *		data is accepted for transmission, -EBUSY while rejecting
+ *		if the remote hasn't yet read the last data sent. Actual
+ *		transmission of data is reported by the controller via
+ *		mbox_chan_txdone (if it has some TX ACK irq). It must not
+ *		sleep.
+ * @startup:	Called when a client requests the chan. The controller
+ *		could ask clients for additional parameters of communication
+ *		to be provided via client's chan_data. This call may
+ *		block. After this call the Controller must forward any
+ *		data received on the chan by calling mbox_chan_received_data.
+ *		The controller may do stuff that need to sleep.
+ * @shutdown:	Called when a client relinquishes control of a chan.
+ *		This call may block too. The controller must not forward
+ *		any received data anymore.
+ *		The controller may do stuff that need to sleep.
+ * @last_tx_done: If the controller sets 'txdone_poll', the API calls
+ *		  this to poll status of last TX. The controller must
+ *		  give priority to IRQ method over polling and never
+ *		  set both txdone_poll and txdone_irq. Only in polling
+ *		  mode 'send_data' is expected to return -EBUSY.
+ *		  The controller may do stuff that need to sleep/block.
+ *		  Used only if txdone_poll:=true && txdone_irq:=false
+ * @peek_data: Atomic check for any received data. Return true if controller
+ *		  has some data to push to the client. False otherwise.
+ */
+struct mbox_chan_ops {
+	int (*send_data)(struct mbox_chan *chan, void *data);
+	int (*startup)(struct mbox_chan *chan);
+	void (*shutdown)(struct mbox_chan *chan);
+	bool (*last_tx_done)(struct mbox_chan *chan);
+	bool (*peek_data)(struct mbox_chan *chan);
+};
+
+/**
+ * struct mbox_controller - Controller of a class of communication channels
+ * @dev:		Device backing this controller
+ * @ops:		Operators that work on each communication chan
+ * @chans:		Array of channels
+ * @num_chans:		Number of channels in the 'chans' array.
+ * @txdone_irq:		Indicates if the controller can report to API when
+ *			the last transmitted data was read by the remote.
+ *			Eg, if it has some TX ACK irq.
+ * @txdone_poll:	If the controller can read but not report the TX
+ *			done. Ex, some register shows the TX status but
+ *			no interrupt rises. Ignored if 'txdone_irq' is set.
+ * @txpoll_period:	If 'txdone_poll' is in effect, the API polls for
+ *			last TX's status after these many millisecs
+ * @of_xlate:		Controller driver specific mapping of channel via DT
+ * @poll:		API private. Used to poll for TXDONE on all channels.
+ * @node:		API private. To hook into list of controllers.
+ */
+struct mbox_controller {
+	struct device *dev;
+	struct mbox_chan_ops *ops;
+	struct mbox_chan *chans;
+	int num_chans;
+	bool txdone_irq;
+	bool txdone_poll;
+	unsigned txpoll_period;
+	struct mbox_chan *(*of_xlate)(struct mbox_controller *mbox,
+				      const struct of_phandle_args *sp);
+	/* Internal to API */
+	struct timer_list poll;
+	struct list_head node;
+};
+
+/*
+ * The length of circular buffer for queuing messages from a client.
+ * 'msg_count' tracks the number of buffered messages while 'msg_free'
+ * is the index where the next message would be buffered.
+ * We shouldn't need it too big because every transfer is interrupt
+ * triggered and if we have lots of data to transfer, the interrupt
+ * latencies are going to be the bottleneck, not the buffer length.
+ * Besides, mbox_send_message could be called from atomic context and
+ * the client could also queue another message from the notifier 'tx_done'
+ * of the last transfer done.
+ * REVISIT: If too many platforms see the "Try increasing MBOX_TX_QUEUE_LEN"
+ * print, it needs to be taken from config option or somesuch.
+ */
+#define MBOX_TX_QUEUE_LEN	20
+
+/**
+ * struct mbox_chan - s/w representation of a communication chan
+ * @mbox:		Pointer to the parent/provider of this channel
+ * @txdone_method:	Way to detect TXDone chosen by the API
+ * @cl:			Pointer to the current owner of this channel
+ * @tx_complete:	Transmission completion
+ * @active_req:		Currently active request hook
+ * @msg_count:		No. of mssg currently queued
+ * @msg_free:		Index of next available mssg slot
+ * @msg_data:		Hook for data packet
+ * @lock:		Serialise access to the channel
+ * @con_priv:		Hook for controller driver to attach private data
+ */
+struct mbox_chan {
+	struct mbox_controller *mbox;
+	unsigned txdone_method;
+	struct mbox_client *cl;
+	struct completion tx_complete;
+	void *active_req;
+	unsigned msg_count, msg_free;
+	void *msg_data[MBOX_TX_QUEUE_LEN];
+	spinlock_t lock; /* Serialise access to the channel */
+	void *con_priv;
+};
+
+int mbox_controller_register(struct mbox_controller *mbox); /* can sleep */
+void mbox_controller_unregister(struct mbox_controller *mbox); /* can sleep */
+void mbox_chan_received_data(struct mbox_chan *chan, void *data); /* atomic */
+void mbox_chan_txdone(struct mbox_chan *chan, int r); /* atomic */
+
+#endif /* __MAILBOX_CONTROLLER_H */