path: root/drivers/mailbox/arm_mhu.c

/*
 * Copyright (C) 2013-2015 Fujitsu Semiconductor Ltd.
 * Copyright (C) 2015 Linaro Ltd.
 * Author: Jassi Brar <jaswinder.singh@linaro.org>
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, version 2 of the License.
 *
 * This program is distributed in the hope that 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.
 */

#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_NUM_PCHANS	3	/* Secure, Non-Secure High and Low Priority */
#define MHU_CHAN_MAX	20	/* Max channels to save on unused RAM */

struct mhu_link {
	unsigned irq;
	void __iomem *tx_reg;
	void __iomem *rx_reg;
};

struct arm_mhu {
	void __iomem *base;
	struct mhu_link mlink[MHU_NUM_PCHANS];
	struct mbox_controller mbox;
	struct device *dev;
};

/**
 * ARM MHU Mailbox platform specific configuration
 *
 * @num_pchans: Maximum number of physical channels
 * @num_doorbells: Maximum number of doorbells per physical channel
 */
struct mhu_mbox_pdata {
	unsigned int num_pchans;
	unsigned int num_doorbells;
	bool support_doorbells;
};

/**
 * 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_channel {
	struct arm_mhu *mhu;
	unsigned int pchan;
	unsigned int doorbell;
};

static inline struct mbox_chan *
mhu_mbox_to_channel(struct mbox_controller *mbox,
		    unsigned int pchan, unsigned int doorbell)
{
	int i;
	struct mhu_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];
	}

	dev_err(mbox->dev,
		"Channel not registered: physical channel: %d doorbell: %d\n",
		pchan, doorbell);

	return NULL;
}

static void mhu_mbox_clear_irq(struct mbox_chan *chan)
{
	struct mhu_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_mbox_irq_to_pchan_num(struct arm_mhu *mhu, int irq)
{
	unsigned int pchan;
	struct mhu_mbox_pdata *pdata = dev_get_platdata(mhu->dev);

	for (pchan = 0; pchan < pdata->num_pchans; pchan++)
		if (mhu->mlink[pchan].irq == irq)
			break;
	return pchan;
}

static struct mbox_chan *mhu_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_mbox_to_channel(mbox, pchan, doorbell);
		if (chan)
			break;
	}

	return chan;
}

static irqreturn_t mhu_mbox_thread_handler(int irq, void *data)
{
	struct mbox_chan *chan;
	struct arm_mhu *mhu = data;
	unsigned int pchan = mhu_mbox_irq_to_pchan_num(mhu, irq);

	while (NULL != (chan = mhu_mbox_irq_to_channel(mhu, pchan))) {
		mbox_chan_received_data(chan, NULL);
		mhu_mbox_clear_irq(chan);
	}

	return IRQ_HANDLED;
}

static bool mhu_doorbell_last_tx_done(struct mbox_chan *chan)
{
	struct mhu_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_doorbell_send_data(struct mbox_chan *chan, void *data)
{
	struct mhu_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_doorbell_startup(struct mbox_chan *chan)
{
	mhu_mbox_clear_irq(chan);
	return 0;
}

static void mhu_doorbell_shutdown(struct mbox_chan *chan)
{
	struct mhu_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_mbox_clear_irq(chan);
	chan->con_priv = NULL;
}

static struct mbox_chan *mhu_mbox_xlate(struct mbox_controller *mbox,
					const struct of_phandle_args *spec)
{
	struct arm_mhu *mhu = dev_get_drvdata(mbox->dev);
	struct mhu_mbox_pdata *pdata = dev_get_platdata(mhu->dev);
	struct mhu_channel *chan_info;
	struct mbox_chan *chan = NULL;
	unsigned int pchan = spec->args[0];
	unsigned int doorbell = pdata->support_doorbells ? spec->args[1] : 0;
	int i;

	/* Bounds checking */
	if (pchan >= pdata->num_pchans || doorbell >= pdata->num_doorbells) {
		dev_err(mbox->dev,
			"Invalid channel requested pchan: %d doorbell: %d\n",
			pchan, doorbell);
		return ERR_PTR(-EINVAL);
	}

	for (i = 0; i < mbox->num_chans; i++) {
		chan_info = mbox->chans[i].con_priv;

		/* Is requested channel free? */
		if (chan_info &&
		    mbox->dev == chan_info->mhu->dev &&
		    pchan == chan_info->pchan &&
		    doorbell == chan_info->doorbell) {
			dev_err(mbox->dev, "Channel in use\n");
			return ERR_PTR(-EBUSY);
		}

		/*
		 * Find the first free slot, then continue checking
		 * to see if requested channel is in use
		 */
		if (!chan && !chan_info)
			chan = &mbox->chans[i];
	}

	if (!chan) {
		dev_err(mbox->dev, "No free channels left\n");
		return ERR_PTR(-EBUSY);
	}

	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 irqreturn_t mhu_rx_interrupt(int irq, void *p)
{
	struct arm_mhu *mhu = p;
	unsigned int pchan = mhu_mbox_irq_to_pchan_num(mhu, irq);
	struct mbox_chan *chan = mhu_mbox_to_channel(&mhu->mbox, pchan, 0);
	void __iomem *base = mhu->mlink[pchan].rx_reg;
	u32 val;

	val = readl_relaxed(base + INTR_STAT_OFS);
	if (!val)
		return IRQ_NONE;

	mbox_chan_received_data(chan, (void *)&val);

	writel_relaxed(val, base + INTR_CLR_OFS);

	return IRQ_HANDLED;
}

static bool mhu_last_tx_done(struct mbox_chan *chan)
{
	struct mhu_channel *chan_info = chan->con_priv;
	void __iomem *base = chan_info->mhu->mlink[chan_info->pchan].tx_reg;
	u32 val = readl_relaxed(base + INTR_STAT_OFS);

	return (val == 0);
}

static int mhu_send_data(struct mbox_chan *chan, void *data)
{
	struct mhu_channel *chan_info = chan->con_priv;
	void __iomem *base = chan_info->mhu->mlink[chan_info->pchan].tx_reg;
	u32 *arg = data;

	writel_relaxed(*arg, base + INTR_SET_OFS);

	return 0;
}

static int mhu_startup(struct mbox_chan *chan)
{
	struct mhu_channel *chan_info = chan->con_priv;
	void __iomem *base = chan_info->mhu->mlink[chan_info->pchan].tx_reg;
	u32 val;

	val = readl_relaxed(base + INTR_STAT_OFS);
	writel_relaxed(val, base + INTR_CLR_OFS);

	return 0;
}

static const struct mbox_chan_ops mhu_ops = {
	.send_data = mhu_send_data,
	.startup = mhu_startup,
	.last_tx_done = mhu_last_tx_done,
};

static const struct mbox_chan_ops mhu_doorbell_ops = {
	.send_data = mhu_doorbell_send_data,
	.startup = mhu_doorbell_startup,
	.shutdown = mhu_doorbell_shutdown,
	.last_tx_done = mhu_doorbell_last_tx_done,
};

static const struct mhu_mbox_pdata arm_mhu_pdata = {
	.num_pchans = 3,
	.num_doorbells = 1,
	.support_doorbells = false,
};

static const struct mhu_mbox_pdata arm_mhu_doorbell_pdata = {
	.num_pchans = 2,	/* Secure can't be used */
	.num_doorbells = 32,
	.support_doorbells = true,
};

static int mhu_probe(struct amba_device *adev, const struct amba_id *id)
{
	u32 cell_count;
	int i, err, max_chans;
	irq_handler_t handler;
	struct arm_mhu *mhu;
	struct mbox_chan *chans;
	struct mhu_mbox_pdata *pdata;
	struct device *dev = &adev->dev;
	struct device_node *np = dev->of_node;
	int mhu_reg[MHU_NUM_PCHANS] = {
		MHU_LP_OFFSET, MHU_HP_OFFSET, MHU_SEC_OFFSET,
	};

	err = of_property_read_u32(np, "#mbox-cells", &cell_count);
	if (err) {
		dev_err(dev, "failed to read #mbox-cells in %s\n",
			np->full_name);
		return err;
	}

	if (cell_count == 1) {
		max_chans = MHU_NUM_PCHANS;
		pdata = (struct mhu_mbox_pdata *)&arm_mhu_pdata;
	} else if (cell_count == 2) {
		max_chans = MHU_CHAN_MAX;
		pdata = (struct mhu_mbox_pdata *)&arm_mhu_doorbell_pdata;
	} else {
		dev_err(dev, "incorrect value of #mbox-cells in %s\n",
			np->full_name);
		return -EINVAL;
	}

	if (pdata->num_pchans > MHU_NUM_PCHANS) {
		dev_err(dev, "Number of physical channel can't exceed %d\n",
			MHU_NUM_PCHANS);
		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;

	dev->platform_data = pdata;

	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_mbox_xlate;
	amba_set_drvdata(adev, mhu);

	if (pdata->support_doorbells) {
		mhu->mbox.ops = &mhu_doorbell_ops;
		handler = mhu_mbox_thread_handler;
	} else {
		mhu->mbox.ops = &mhu_ops;
		handler = mhu_rx_interrupt;
	}

	err = mbox_controller_register(&mhu->mbox);
	if (err) {
		dev_err(dev, "Failed to register mailboxes %d\n", err);
		return err;
	}

	for (i = 0; i < pdata->num_pchans; 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, handler,
						IRQF_ONESHOT, "mhu_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 Mailbox registered\n");
	return 0;
}

static int mhu_remove(struct amba_device *adev)
{
	struct arm_mhu *mhu = amba_get_drvdata(adev);

	mbox_controller_unregister(&mhu->mbox);

	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_driver = {
	.drv = {
		.name	= "mhu",
	},
	.id_table	= mhu_ids,
	.probe		= mhu_probe,
	.remove		= mhu_remove,
};
module_amba_driver(arm_mhu_driver);

MODULE_LICENSE("GPL v2");
MODULE_DESCRIPTION("ARM MHU Driver");
MODULE_AUTHOR("Jassi Brar <jassisinghbrar@gmail.com>");