Commit f62092f6 authored by Ley Foon Tan's avatar Ley Foon Tan Committed by Jassi Brar
Browse files

mailbox: Add Altera mailbox driver 



The Altera mailbox allows for interprocessor communication. It supports
only one channel and work as either sender or receiver.

Signed-off-by: default avatarLey Foon Tan <lftan@altera.com>
parent 01340df8

Documentation/devicetree/bindings/mailbox/altera-mailbox.txt

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Altera Mailbox Driver

=====================



Required properties:

- compatible :	"altr,mailbox-1.0".

- reg : 	physical base address of the mailbox and length of

		memory mapped region.

- #mbox-cells:	Common mailbox binding property to identify the number

		of cells required for the mailbox specifier. Should be 1.



Optional properties:

- interrupt-parent :	interrupt source phandle.

- interrupts :		interrupt number. The interrupt specifier format

			depends on the interrupt controller parent.



Example:

	mbox_tx: mailbox@0x100 {

		compatible = "altr,mailbox-1.0";

		reg = <0x100 0x8>;

		interrupt-parent = < &gic_0 >;

		interrupts = <5>;

		#mbox-cells = <1>;

	};



	mbox_rx: mailbox@0x200 {

		compatible = "altr,mailbox-1.0";

		reg = <0x200 0x8>;

		interrupt-parent = < &gic_0 >;

		interrupts = <6>;

		#mbox-cells = <1>;

	};



Mailbox client

===============

"mboxes" and the optional "mbox-names" (please see

Documentation/devicetree/bindings/mailbox/mailbox.txt for details). Each value

of the mboxes property should contain a phandle to the mailbox controller

device node and second argument is the channel index. It must be 0 (hardware

support only one channel).The equivalent "mbox-names" property value can be

used to give a name to the communication channel to be used by the client user.



Example:

	mclient0: mclient0@0x400 {

		compatible = "client-1.0";

		reg = <0x400 0x10>;

		mbox-names = "mbox-tx", "mbox-rx";

		mboxes = <&mbox_tx 0>,

			 <&mbox_rx 0>;

	};

MAINTAINERS

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@@ -563,6 +563,12 @@ S: Odd Fixes 
L:	linux-alpha@vger.kernel.org

F:	arch/alpha/



ALTERA MAILBOX DRIVER

M:	Ley Foon Tan <lftan@altera.com>

L:	nios2-dev@lists.rocketboards.org (moderated for non-subscribers)

S:	Maintained

F:	drivers/mailbox/mailbox-altera.c



ALTERA TRIPLE SPEED ETHERNET DRIVER

M:	Vince Bridgers <vbridger@opensource.altera.com>

L:	netdev@vger.kernel.org

drivers/mailbox/Kconfig

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@@ -45,4 +45,10 @@ config PCC 
	  states). Select this driver if your platform implements the

	  PCC clients mentioned above.



config ALTERA_MBOX

	tristate "Altera Mailbox"

	help

	  An implementation of the Altera Mailbox soft core. It is used

	  to send message between processors. Say Y here if you want to use the

	  Altera mailbox support.

endif

drivers/mailbox/Makefile

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@@ -7,3 +7,5 @@ obj-$(CONFIG_PL320_MBOX) += pl320-ipc.o 
obj-$(CONFIG_OMAP2PLUS_MBOX)	+= omap-mailbox.o



obj-$(CONFIG_PCC)		+= pcc.o



obj-$(CONFIG_ALTERA_MBOX)	+= mailbox-altera.o

drivers/mailbox/mailbox-altera.c

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/*

 * Copyright Altera Corporation (C) 2013-2014. All rights reserved

 *

 * This program is free software; you can redistribute it and/or modify it

 * under the terms and conditions of the GNU General Public License,

 * version 2, as published by the Free Software Foundation.

 *

 * This program is distributed in the hope it will be useful, but WITHOUT

 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for

 * more details.

 *

 * You should have received a copy of the GNU General Public License along with

 * this program.  If not, see <http://www.gnu.org/licenses/>.

 */



#include <linux/device.h>

#include <linux/interrupt.h>

#include <linux/io.h>

#include <linux/kernel.h>

#include <linux/mailbox_controller.h>

#include <linux/module.h>

#include <linux/of.h>

#include <linux/platform_device.h>



#define DRIVER_NAME	"altera-mailbox"



#define MAILBOX_CMD_REG			0x00

#define MAILBOX_PTR_REG			0x04

#define MAILBOX_STS_REG			0x08

#define MAILBOX_INTMASK_REG		0x0C



#define INT_PENDING_MSK			0x1

#define INT_SPACE_MSK			0x2



#define STS_PENDING_MSK			0x1

#define STS_FULL_MSK			0x2

#define STS_FULL_OFT			0x1



#define MBOX_PENDING(status)	(((status) & STS_PENDING_MSK))

#define MBOX_FULL(status)	(((status) & STS_FULL_MSK) >> STS_FULL_OFT)



enum altera_mbox_msg {

	MBOX_CMD = 0,

	MBOX_PTR,

};



#define MBOX_POLLING_MS		5	/* polling interval 5ms */



struct altera_mbox {

	bool is_sender;		/* 1-sender, 0-receiver */

	bool intr_mode;

	int irq;

	void __iomem *mbox_base;

	struct device *dev;

	struct mbox_controller controller;



	/* If the controller supports only RX polling mode */

	struct timer_list rxpoll_timer;

};



static struct altera_mbox *mbox_chan_to_altera_mbox(struct mbox_chan *chan)

{

	if (!chan || !chan->con_priv)

		return NULL;



	return (struct altera_mbox *)chan->con_priv;

}



static inline int altera_mbox_full(struct altera_mbox *mbox)

{

	u32 status;



	status = readl_relaxed(mbox->mbox_base + MAILBOX_STS_REG);

	return MBOX_FULL(status);

}



static inline int altera_mbox_pending(struct altera_mbox *mbox)

{

	u32 status;



	status = readl_relaxed(mbox->mbox_base + MAILBOX_STS_REG);

	return MBOX_PENDING(status);

}



static void altera_mbox_rx_intmask(struct altera_mbox *mbox, bool enable)

{

	u32 mask;



	mask = readl_relaxed(mbox->mbox_base + MAILBOX_INTMASK_REG);

	if (enable)

		mask |= INT_PENDING_MSK;

	else

		mask &= ~INT_PENDING_MSK;

	writel_relaxed(mask, mbox->mbox_base + MAILBOX_INTMASK_REG);

}



static void altera_mbox_tx_intmask(struct altera_mbox *mbox, bool enable)

{

	u32 mask;



	mask = readl_relaxed(mbox->mbox_base + MAILBOX_INTMASK_REG);

	if (enable)

		mask |= INT_SPACE_MSK;

	else

		mask &= ~INT_SPACE_MSK;

	writel_relaxed(mask, mbox->mbox_base + MAILBOX_INTMASK_REG);

}



static bool altera_mbox_is_sender(struct altera_mbox *mbox)

{

	u32 reg;

	/* Write a magic number to PTR register and read back this register.

	 * This register is read-write if it is a sender.

	 */

	#define MBOX_MAGIC	0xA5A5AA55

	writel_relaxed(MBOX_MAGIC, mbox->mbox_base + MAILBOX_PTR_REG);

	reg = readl_relaxed(mbox->mbox_base + MAILBOX_PTR_REG);

	if (reg == MBOX_MAGIC) {

		/* Clear to 0 */

		writel_relaxed(0, mbox->mbox_base + MAILBOX_PTR_REG);

		return true;

	}

	return false;

}



static void altera_mbox_rx_data(struct mbox_chan *chan)

{

	struct altera_mbox *mbox = mbox_chan_to_altera_mbox(chan);

	u32 data[2];



	if (altera_mbox_pending(mbox)) {

		data[MBOX_PTR] =

			readl_relaxed(mbox->mbox_base + MAILBOX_PTR_REG);

		data[MBOX_CMD] =

			readl_relaxed(mbox->mbox_base + MAILBOX_CMD_REG);

		mbox_chan_received_data(chan, (void *)data);

	}

}



static void altera_mbox_poll_rx(unsigned long data)

{

	struct mbox_chan *chan = (struct mbox_chan *)data;

	struct altera_mbox *mbox = mbox_chan_to_altera_mbox(chan);



	altera_mbox_rx_data(chan);



	mod_timer(&mbox->rxpoll_timer,

		  jiffies + msecs_to_jiffies(MBOX_POLLING_MS));

}



static irqreturn_t altera_mbox_tx_interrupt(int irq, void *p)

{

	struct mbox_chan *chan = (struct mbox_chan *)p;

	struct altera_mbox *mbox = mbox_chan_to_altera_mbox(chan);



	altera_mbox_tx_intmask(mbox, false);

	mbox_chan_txdone(chan, 0);



	return IRQ_HANDLED;

}



static irqreturn_t altera_mbox_rx_interrupt(int irq, void *p)

{

	struct mbox_chan *chan = (struct mbox_chan *)p;



	altera_mbox_rx_data(chan);

	return IRQ_HANDLED;

}



static int altera_mbox_startup_sender(struct mbox_chan *chan)

{

	int ret;

	struct altera_mbox *mbox = mbox_chan_to_altera_mbox(chan);



	if (mbox->intr_mode) {

		ret = request_irq(mbox->irq, altera_mbox_tx_interrupt, 0,

				  DRIVER_NAME, chan);

		if (unlikely(ret)) {

			dev_err(mbox->dev,

				"failed to register mailbox interrupt:%d\n",

				ret);

			return ret;

		}

	}



	return 0;

}



static int altera_mbox_startup_receiver(struct mbox_chan *chan)

{

	int ret;

	struct altera_mbox *mbox = mbox_chan_to_altera_mbox(chan);



	if (mbox->intr_mode) {

		ret = request_irq(mbox->irq, altera_mbox_rx_interrupt, 0,

				  DRIVER_NAME, chan);

		if (unlikely(ret)) {

			mbox->intr_mode = false;

			goto polling; /* use polling if failed */

		}



		altera_mbox_rx_intmask(mbox, true);

		return 0;

	}



polling:

	/* Setup polling timer */

	setup_timer(&mbox->rxpoll_timer, altera_mbox_poll_rx,

		    (unsigned long)chan);

	mod_timer(&mbox->rxpoll_timer,

		  jiffies + msecs_to_jiffies(MBOX_POLLING_MS));



	return 0;

}



static int altera_mbox_send_data(struct mbox_chan *chan, void *data)

{

	struct altera_mbox *mbox = mbox_chan_to_altera_mbox(chan);

	u32 *udata = (u32 *)data;



	if (!mbox || !data)

		return -EINVAL;

	if (!mbox->is_sender) {

		dev_warn(mbox->dev,

			 "failed to send. This is receiver mailbox.\n");

		return -EINVAL;

	}



	if (altera_mbox_full(mbox))

		return -EBUSY;



	/* Enable interrupt before send */

	if (mbox->intr_mode)

		altera_mbox_tx_intmask(mbox, true);



	/* Pointer register must write before command register */

	writel_relaxed(udata[MBOX_PTR], mbox->mbox_base + MAILBOX_PTR_REG);

	writel_relaxed(udata[MBOX_CMD], mbox->mbox_base + MAILBOX_CMD_REG);



	return 0;

}



static bool altera_mbox_last_tx_done(struct mbox_chan *chan)

{

	struct altera_mbox *mbox = mbox_chan_to_altera_mbox(chan);



	/* Return false if mailbox is full */

	return altera_mbox_full(mbox) ? false : true;

}



static bool altera_mbox_peek_data(struct mbox_chan *chan)

{

	struct altera_mbox *mbox = mbox_chan_to_altera_mbox(chan);



	return altera_mbox_pending(mbox) ? true : false;

}



static int altera_mbox_startup(struct mbox_chan *chan)

{

	struct altera_mbox *mbox = mbox_chan_to_altera_mbox(chan);

	int ret = 0;



	if (!mbox)

		return -EINVAL;



	if (mbox->is_sender)

		ret = altera_mbox_startup_sender(chan);

	else

		ret = altera_mbox_startup_receiver(chan);



	return ret;

}



static void altera_mbox_shutdown(struct mbox_chan *chan)

{

	struct altera_mbox *mbox = mbox_chan_to_altera_mbox(chan);



	if (mbox->intr_mode) {

		/* Unmask all interrupt masks */

		writel_relaxed(~0, mbox->mbox_base + MAILBOX_INTMASK_REG);

		free_irq(mbox->irq, chan);

	} else if (!mbox->is_sender) {

		del_timer_sync(&mbox->rxpoll_timer);

	}

}



static struct mbox_chan_ops altera_mbox_ops = {

	.send_data = altera_mbox_send_data,

	.startup = altera_mbox_startup,

	.shutdown = altera_mbox_shutdown,

	.last_tx_done = altera_mbox_last_tx_done,

	.peek_data = altera_mbox_peek_data,

};



static int altera_mbox_probe(struct platform_device *pdev)

{

	struct altera_mbox *mbox;

	struct resource	*regs;

	struct mbox_chan *chans;

	int ret;



	mbox = devm_kzalloc(&pdev->dev, sizeof(*mbox),

			    GFP_KERNEL);

	if (!mbox)

		return -ENOMEM;



	/* Allocated one channel */

	chans = devm_kzalloc(&pdev->dev, sizeof(*chans), GFP_KERNEL);

	if (!chans)

		return -ENOMEM;



	regs = platform_get_resource(pdev, IORESOURCE_MEM, 0);



	mbox->mbox_base = devm_ioremap_resource(&pdev->dev, regs);

	if (IS_ERR(mbox->mbox_base))

		return PTR_ERR(mbox->mbox_base);



	/* Check is it a sender or receiver? */

	mbox->is_sender = altera_mbox_is_sender(mbox);



	mbox->irq = platform_get_irq(pdev, 0);

	if (mbox->irq >= 0)

		mbox->intr_mode = true;



	mbox->dev = &pdev->dev;



	/* Hardware supports only one channel. */

	chans[0].con_priv = mbox;

	mbox->controller.dev = mbox->dev;

	mbox->controller.num_chans = 1;

	mbox->controller.chans = chans;

	mbox->controller.ops = &altera_mbox_ops;



	if (mbox->is_sender) {

		if (mbox->intr_mode) {

			mbox->controller.txdone_irq = true;

		} else {

			mbox->controller.txdone_poll = true;

			mbox->controller.txpoll_period = MBOX_POLLING_MS;

		}

	}



	ret = mbox_controller_register(&mbox->controller);

	if (ret) {

		dev_err(&pdev->dev, "Register mailbox failed\n");

		goto err;

	}



	platform_set_drvdata(pdev, mbox);

err:

	return ret;

}



static int altera_mbox_remove(struct platform_device *pdev)

{

	struct altera_mbox *mbox = platform_get_drvdata(pdev);



	if (!mbox)

		return -EINVAL;



	mbox_controller_unregister(&mbox->controller);



	return 0;

}



static const struct of_device_id altera_mbox_match[] = {

	{ .compatible = "altr,mailbox-1.0" },

	{ /* Sentinel */ }

};



MODULE_DEVICE_TABLE(of, altera_mbox_match);



static struct platform_driver altera_mbox_driver = {

	.probe	= altera_mbox_probe,

	.remove	= altera_mbox_remove,

	.driver	= {

		.name	= DRIVER_NAME,

		.of_match_table	= altera_mbox_match,

	},

};



module_platform_driver(altera_mbox_driver);



MODULE_LICENSE("GPL v2");

MODULE_DESCRIPTION("Altera mailbox specific functions");

MODULE_AUTHOR("Ley Foon Tan <lftan@altera.com>");

MODULE_ALIAS("platform:altera-mailbox");

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