drivers/mailbox/arm_mhu_db.c - linux - Git at Google

 // 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>

 #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;
 };

 /**
  * struct mhu_db_channel - 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);
 	devm_kfree(mbox->dev, 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))
 		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>");
	// 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>

	#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;
	};

	/**
	* struct mhu_db_channel - 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);
	devm_kfree(mbox->dev, 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))
	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>");