mailbox: arm_mhu: Add ARM MHU doorbell driver

obj-$(CONFIG_MAILBOX_TEST)	+= mailbox-test.o

obj-$(CONFIG_ARM_MHU)	+= arm_mhu.o

obj-$(CONFIG_ARM_MHU)	+= arm_mhu.o arm_mhu_db.o

obj-$(CONFIG_IMX_MBOX)	+= imx-mailbox.o

// SPDX-License-Identifier: GPL-2.0-only

/*

 * Copyright (C) 2013-2015 Fujitsu Semiconductor Ltd.

 * Copyright (C) 2015 Linaro Ltd.

 * Based on ARM MHU driver by Jassi Brar <jaswinder.singh@linaro.org>

 * Copyright (C) 2020 ARM Ltd.

 */

#include <linux/amba/bus.h>

#include <linux/device.h>

#include <linux/err.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/of_device.h>

#define INTR_STAT_OFS	0x0

#define INTR_SET_OFS	0x8

#define INTR_CLR_OFS	0x10

#define MHU_LP_OFFSET	0x0

#define MHU_HP_OFFSET	0x20

#define MHU_SEC_OFFSET	0x200

#define TX_REG_OFFSET	0x100

#define MHU_CHANS	3	/* Secure, Non-Secure High and Low Priority */

#define MHU_CHAN_MAX	20	/* Max channels to save on unused RAM */

#define MHU_NUM_DOORBELLS	32

struct mhu_db_link {

	unsigned int irq;

	void __iomem *tx_reg;

	void __iomem *rx_reg;

};

struct arm_mhu {

	void __iomem *base;

	struct mhu_db_link mlink[MHU_CHANS];

	struct mbox_controller mbox;

	struct device *dev;

};

/**

 * ARM MHU Mailbox allocated channel information

 *

 * @mhu: Pointer to parent mailbox device

 * @pchan: Physical channel within which this doorbell resides in

 * @doorbell: doorbell number pertaining to this channel

 */

struct mhu_db_channel {

	struct arm_mhu *mhu;

	unsigned int pchan;

	unsigned int doorbell;

};

static inline struct mbox_chan *

mhu_db_mbox_to_channel(struct mbox_controller *mbox, unsigned int pchan,

		       unsigned int doorbell)

{

	int i;

	struct mhu_db_channel *chan_info;

	for (i = 0; i < mbox->num_chans; i++) {

		chan_info = mbox->chans[i].con_priv;

		if (chan_info && chan_info->pchan == pchan &&

		    chan_info->doorbell == doorbell)

			return &mbox->chans[i];

	}

	return NULL;

}

static void mhu_db_mbox_clear_irq(struct mbox_chan *chan)

{

	struct mhu_db_channel *chan_info = chan->con_priv;

	void __iomem *base = chan_info->mhu->mlink[chan_info->pchan].rx_reg;

	writel_relaxed(BIT(chan_info->doorbell), base + INTR_CLR_OFS);

}

static unsigned int mhu_db_mbox_irq_to_pchan_num(struct arm_mhu *mhu, int irq)

{

	unsigned int pchan;

	for (pchan = 0; pchan < MHU_CHANS; pchan++)

		if (mhu->mlink[pchan].irq == irq)

			break;

	return pchan;

}

static struct mbox_chan *

mhu_db_mbox_irq_to_channel(struct arm_mhu *mhu, unsigned int pchan)

{

	unsigned long bits;

	unsigned int doorbell;

	struct mbox_chan *chan = NULL;

	struct mbox_controller *mbox = &mhu->mbox;

	void __iomem *base = mhu->mlink[pchan].rx_reg;

	bits = readl_relaxed(base + INTR_STAT_OFS);

	if (!bits)

		/* No IRQs fired in specified physical channel */

		return NULL;

	/* An IRQ has fired, find the associated channel */

	for (doorbell = 0; bits; doorbell++) {

		if (!test_and_clear_bit(doorbell, &bits))

			continue;

		chan = mhu_db_mbox_to_channel(mbox, pchan, doorbell);

		if (chan)

			break;

		dev_err(mbox->dev,

			"Channel not registered: pchan: %d doorbell: %d\n",

			pchan, doorbell);

	}

	return chan;

}

static irqreturn_t mhu_db_mbox_rx_handler(int irq, void *data)

{

	struct mbox_chan *chan;

	struct arm_mhu *mhu = data;

	unsigned int pchan = mhu_db_mbox_irq_to_pchan_num(mhu, irq);

	while (NULL != (chan = mhu_db_mbox_irq_to_channel(mhu, pchan))) {

		mbox_chan_received_data(chan, NULL);

		mhu_db_mbox_clear_irq(chan);

	}

	return IRQ_HANDLED;

}

static bool mhu_db_last_tx_done(struct mbox_chan *chan)

{

	struct mhu_db_channel *chan_info = chan->con_priv;

	void __iomem *base = chan_info->mhu->mlink[chan_info->pchan].tx_reg;

	if (readl_relaxed(base + INTR_STAT_OFS) & BIT(chan_info->doorbell))

		return false;

	return true;

}

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

{

	struct mhu_db_channel *chan_info = chan->con_priv;

	void __iomem *base = chan_info->mhu->mlink[chan_info->pchan].tx_reg;

	/* Send event to co-processor */

	writel_relaxed(BIT(chan_info->doorbell), base + INTR_SET_OFS);

	return 0;

}

static int mhu_db_startup(struct mbox_chan *chan)

{

	mhu_db_mbox_clear_irq(chan);

	return 0;

}

static void mhu_db_shutdown(struct mbox_chan *chan)

{

	struct mhu_db_channel *chan_info = chan->con_priv;

	struct mbox_controller *mbox = &chan_info->mhu->mbox;

	int i;

	for (i = 0; i < mbox->num_chans; i++)

		if (chan == &mbox->chans[i])

			break;

	if (mbox->num_chans == i) {

		dev_warn(mbox->dev, "Request to free non-existent channel\n");

		return;

	}

	/* Reset channel */

	mhu_db_mbox_clear_irq(chan);

	kfree(chan->con_priv);

	chan->con_priv = NULL;

}

static struct mbox_chan *mhu_db_mbox_xlate(struct mbox_controller *mbox,

					   const struct of_phandle_args *spec)

{

	struct arm_mhu *mhu = dev_get_drvdata(mbox->dev);

	struct mhu_db_channel *chan_info;

	struct mbox_chan *chan;

	unsigned int pchan = spec->args[0];

	unsigned int doorbell = spec->args[1];

	int i;

	/* Bounds checking */

	if (pchan >= MHU_CHANS || doorbell >= MHU_NUM_DOORBELLS) {

		dev_err(mbox->dev,

			"Invalid channel requested pchan: %d doorbell: %d\n",

			pchan, doorbell);

		return ERR_PTR(-EINVAL);

	}

	/* Is requested channel free? */

	chan = mhu_db_mbox_to_channel(mbox, pchan, doorbell);

	if (chan) {

		dev_err(mbox->dev, "Channel in use: pchan: %d doorbell: %d\n",

			pchan, doorbell);

		return ERR_PTR(-EBUSY);

	}

	/* Find the first free slot */

	for (i = 0; i < mbox->num_chans; i++)

		if (!mbox->chans[i].con_priv)

			break;

	if (mbox->num_chans == i) {

		dev_err(mbox->dev, "No free channels left\n");

		return ERR_PTR(-EBUSY);

	}

	chan = &mbox->chans[i];

	chan_info = devm_kzalloc(mbox->dev, sizeof(*chan_info), GFP_KERNEL);

	if (!chan_info)

		return ERR_PTR(-ENOMEM);

	chan_info->mhu = mhu;

	chan_info->pchan = pchan;

	chan_info->doorbell = doorbell;

	chan->con_priv = chan_info;

	dev_dbg(mbox->dev, "mbox: created channel phys: %d doorbell: %d\n",

		pchan, doorbell);

	return chan;

}

static const struct mbox_chan_ops mhu_db_ops = {

	.send_data = mhu_db_send_data,

	.startup = mhu_db_startup,

	.shutdown = mhu_db_shutdown,

	.last_tx_done = mhu_db_last_tx_done,

};

static int mhu_db_probe(struct amba_device *adev, const struct amba_id *id)

{

	u32 cell_count;

	int i, err, max_chans;

	struct arm_mhu *mhu;

	struct mbox_chan *chans;

	struct device *dev = &adev->dev;

	struct device_node *np = dev->of_node;

	int mhu_reg[MHU_CHANS] = {

		MHU_LP_OFFSET, MHU_HP_OFFSET, MHU_SEC_OFFSET,

	};

	if (!of_device_is_compatible(np, "arm,mhu-doorbell"))

		return -ENODEV;

	err = of_property_read_u32(np, "#mbox-cells", &cell_count);

	if (err) {

		dev_err(dev, "failed to read #mbox-cells in '%pOF'\n", np);

		return err;

	}

	if (cell_count == 2) {

		max_chans = MHU_CHAN_MAX;

	} else {

		dev_err(dev, "incorrect value of #mbox-cells in '%pOF'\n", np);

		return -EINVAL;

	}

	mhu = devm_kzalloc(dev, sizeof(*mhu), GFP_KERNEL);

	if (!mhu)

		return -ENOMEM;

	mhu->base = devm_ioremap_resource(dev, &adev->res);

	if (IS_ERR(mhu->base)) {

		dev_err(dev, "ioremap failed\n");

		return PTR_ERR(mhu->base);

	}

	chans = devm_kcalloc(dev, max_chans, sizeof(*chans), GFP_KERNEL);

	if (!chans)

		return -ENOMEM;

	mhu->dev = dev;

	mhu->mbox.dev = dev;

	mhu->mbox.chans = chans;

	mhu->mbox.num_chans = max_chans;

	mhu->mbox.txdone_irq = false;

	mhu->mbox.txdone_poll = true;

	mhu->mbox.txpoll_period = 1;

	mhu->mbox.of_xlate = mhu_db_mbox_xlate;

	amba_set_drvdata(adev, mhu);

	mhu->mbox.ops = &mhu_db_ops;

	err = devm_mbox_controller_register(dev, &mhu->mbox);

	if (err) {

		dev_err(dev, "Failed to register mailboxes %d\n", err);

		return err;

	}

	for (i = 0; i < MHU_CHANS; i++) {

		int irq = mhu->mlink[i].irq = adev->irq[i];

		if (irq <= 0) {

			dev_dbg(dev, "No IRQ found for Channel %d\n", i);

			continue;

		}

		mhu->mlink[i].rx_reg = mhu->base + mhu_reg[i];

		mhu->mlink[i].tx_reg = mhu->mlink[i].rx_reg + TX_REG_OFFSET;

		err = devm_request_threaded_irq(dev, irq, NULL,

						mhu_db_mbox_rx_handler,

						IRQF_ONESHOT, "mhu_db_link", mhu);

		if (err) {

			dev_err(dev, "Can't claim IRQ %d\n", irq);

			mbox_controller_unregister(&mhu->mbox);

			return err;

		}

	}

	dev_info(dev, "ARM MHU Doorbell mailbox registered\n");

	return 0;

}

static struct amba_id mhu_ids[] = {

	{

		.id	= 0x1bb098,

		.mask	= 0xffffff,

	},

	{ 0, 0 },

};

MODULE_DEVICE_TABLE(amba, mhu_ids);

static struct amba_driver arm_mhu_db_driver = {

	.drv = {

		.name	= "mhu-doorbell",

	},

	.id_table	= mhu_ids,

	.probe		= mhu_db_probe,

};

module_amba_driver(arm_mhu_db_driver);

MODULE_LICENSE("GPL v2");

MODULE_DESCRIPTION("ARM MHU Doorbell Driver");

MODULE_AUTHOR("Sudeep Holla <sudeep.holla@arm.com>");