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

 // SPDX-License-Identifier: GPL-2.0-only
 /*
  * Spreadtrum mailbox driver
  *
  * Copyright (c) 2020 Spreadtrum Communications Inc.
  */

 #include <linux/delay.h>
 #include <linux/err.h>
 #include <linux/interrupt.h>
 #include <linux/io.h>
 #include <linux/mailbox_controller.h>
 #include <linux/module.h>
 #include <linux/of.h>
 #include <linux/platform_device.h>
 #include <linux/clk.h>

 #define SPRD_MBOX_ID		0x0
 #define SPRD_MBOX_MSG_LOW	0x4
 #define SPRD_MBOX_MSG_HIGH	0x8
 #define SPRD_MBOX_TRIGGER	0xc
 #define SPRD_MBOX_FIFO_RST	0x10
 #define SPRD_MBOX_FIFO_STS	0x14
 #define SPRD_MBOX_IRQ_STS	0x18
 #define SPRD_MBOX_IRQ_MSK	0x1c
 #define SPRD_MBOX_LOCK		0x20
 #define SPRD_MBOX_FIFO_DEPTH	0x24

 /* Bit and mask definition for inbox's SPRD_MBOX_FIFO_STS register */
 #define SPRD_INBOX_FIFO_DELIVER_MASK		GENMASK(23, 16)
 #define SPRD_INBOX_FIFO_OVERLOW_MASK		GENMASK(15, 8)
 #define SPRD_INBOX_FIFO_DELIVER_SHIFT		16
 #define SPRD_INBOX_FIFO_BUSY_MASK		GENMASK(7, 0)

 /* Bit and mask definition for SPRD_MBOX_IRQ_STS register */
 #define SPRD_MBOX_IRQ_CLR			BIT(0)

 /* Bit and mask definition for outbox's SPRD_MBOX_FIFO_STS register */
 #define SPRD_OUTBOX_FIFO_FULL			BIT(2)
 #define SPRD_OUTBOX_FIFO_WR_SHIFT		16
 #define SPRD_OUTBOX_FIFO_RD_SHIFT		24
 #define SPRD_OUTBOX_FIFO_POS_MASK		GENMASK(7, 0)

 /* Bit and mask definition for inbox's SPRD_MBOX_IRQ_MSK register */
 #define SPRD_INBOX_FIFO_BLOCK_IRQ		BIT(0)
 #define SPRD_INBOX_FIFO_OVERFLOW_IRQ		BIT(1)
 #define SPRD_INBOX_FIFO_DELIVER_IRQ		BIT(2)
 #define SPRD_INBOX_FIFO_IRQ_MASK		GENMASK(2, 0)

 /* Bit and mask definition for outbox's SPRD_MBOX_IRQ_MSK register */
 #define SPRD_OUTBOX_FIFO_NOT_EMPTY_IRQ		BIT(0)
 #define SPRD_OUTBOX_FIFO_IRQ_MASK		GENMASK(4, 0)

 #define SPRD_OUTBOX_BASE_SPAN			0x1000
 #define SPRD_MBOX_CHAN_MAX			8
 #define SPRD_SUPP_INBOX_ID_SC9863A		7

 struct sprd_mbox_priv {
 	struct mbox_controller	mbox;
 	struct device		*dev;
 	void __iomem		*inbox_base;
 	void __iomem		*outbox_base;
 	/*  Base register address for supplementary outbox */
 	void __iomem		*supp_base;
 	struct clk		*clk;
 	u32			outbox_fifo_depth;

 	struct mutex		lock;
 	u32			refcnt;
 	struct mbox_chan	chan[SPRD_MBOX_CHAN_MAX];
 };

 static struct sprd_mbox_priv *to_sprd_mbox_priv(struct mbox_controller *mbox)
 {
 	return container_of(mbox, struct sprd_mbox_priv, mbox);
 }

 static u32 sprd_mbox_get_fifo_len(struct sprd_mbox_priv *priv, u32 fifo_sts)
 {
 	u32 wr_pos = (fifo_sts >> SPRD_OUTBOX_FIFO_WR_SHIFT) &
 		SPRD_OUTBOX_FIFO_POS_MASK;
 	u32 rd_pos = (fifo_sts >> SPRD_OUTBOX_FIFO_RD_SHIFT) &
 		SPRD_OUTBOX_FIFO_POS_MASK;
 	u32 fifo_len;

 	/*
 	 * If the read pointer is equal with write pointer, which means the fifo
 	 * is full or empty.
 	 */
 	if (wr_pos == rd_pos) {
 		if (fifo_sts & SPRD_OUTBOX_FIFO_FULL)
 			fifo_len = priv->outbox_fifo_depth;
 		else
 			fifo_len = 0;
 	} else if (wr_pos > rd_pos) {
 		fifo_len = wr_pos - rd_pos;
 	} else {
 		fifo_len = priv->outbox_fifo_depth - rd_pos + wr_pos;
 	}

 	return fifo_len;
 }

 static irqreturn_t do_outbox_isr(void __iomem *base, struct sprd_mbox_priv *priv)
 {
 	struct mbox_chan *chan;
 	u32 fifo_sts, fifo_len, msg[2];
 	int i, id;

 	fifo_sts = readl(base + SPRD_MBOX_FIFO_STS);

 	fifo_len = sprd_mbox_get_fifo_len(priv, fifo_sts);
 	if (!fifo_len) {
 		dev_warn_ratelimited(priv->dev, "spurious outbox interrupt\n");
 		return IRQ_NONE;
 	}

 	for (i = 0; i < fifo_len; i++) {
 		msg[0] = readl(base + SPRD_MBOX_MSG_LOW);
 		msg[1] = readl(base + SPRD_MBOX_MSG_HIGH);
 		id = readl(base + SPRD_MBOX_ID);

 		chan = &priv->chan[id];
 		if (chan->cl)
 			mbox_chan_received_data(chan, (void *)msg);
 		else
 			dev_warn_ratelimited(priv->dev,
 				    "message's been dropped at ch[%d]\n", id);

 		/* Trigger to update outbox FIFO pointer */
 		writel(0x1, base + SPRD_MBOX_TRIGGER);
 	}

 	/* Clear irq status after reading all message. */
 	writel(SPRD_MBOX_IRQ_CLR, base + SPRD_MBOX_IRQ_STS);

 	return IRQ_HANDLED;
 }

 static irqreturn_t sprd_mbox_outbox_isr(int irq, void *data)
 {
 	struct sprd_mbox_priv *priv = data;

 	return do_outbox_isr(priv->outbox_base, priv);
 }

 static irqreturn_t sprd_mbox_supp_isr(int irq, void *data)
 {
 	struct sprd_mbox_priv *priv = data;

 	return do_outbox_isr(priv->supp_base, priv);
 }

 static irqreturn_t sprd_mbox_inbox_isr(int irq, void *data)
 {
 	struct sprd_mbox_priv *priv = data;
 	struct mbox_chan *chan;
 	u32 fifo_sts, send_sts, busy, id;

 	fifo_sts = readl(priv->inbox_base + SPRD_MBOX_FIFO_STS);

 	/* Get the inbox data delivery status */
 	send_sts = (fifo_sts & SPRD_INBOX_FIFO_DELIVER_MASK) >>
 		SPRD_INBOX_FIFO_DELIVER_SHIFT;
 	if (!send_sts) {
 		dev_warn_ratelimited(priv->dev, "spurious inbox interrupt\n");
 		return IRQ_NONE;
 	}

 	while (send_sts) {
 		id = __ffs(send_sts);
 		send_sts &= (send_sts - 1);

 		chan = &priv->chan[id];

 		/*
 		 * Check if the message was fetched by remote target, if yes,
 		 * that means the transmission has been completed.
 		 */
 		busy = fifo_sts & SPRD_INBOX_FIFO_BUSY_MASK;
 		if (!(busy & BIT(id)))
 			mbox_chan_txdone(chan, 0);
 	}

 	/* Clear FIFO delivery and overflow status */
 	writel(fifo_sts &
 	       (SPRD_INBOX_FIFO_DELIVER_MASK | SPRD_INBOX_FIFO_OVERLOW_MASK),
 	       priv->inbox_base + SPRD_MBOX_FIFO_RST);

 	/* Clear irq status */
 	writel(SPRD_MBOX_IRQ_CLR, priv->inbox_base + SPRD_MBOX_IRQ_STS);

 	return IRQ_HANDLED;
 }

 static int sprd_mbox_send_data(struct mbox_chan *chan, void *msg)
 {
 	struct sprd_mbox_priv *priv = to_sprd_mbox_priv(chan->mbox);
 	unsigned long id = (unsigned long)chan->con_priv;
 	u32 *data = msg;

 	/* Write data into inbox FIFO, and only support 8 bytes every time */
 	writel(data[0], priv->inbox_base + SPRD_MBOX_MSG_LOW);
 	writel(data[1], priv->inbox_base + SPRD_MBOX_MSG_HIGH);

 	/* Set target core id */
 	writel(id, priv->inbox_base + SPRD_MBOX_ID);

 	/* Trigger remote request */
 	writel(0x1, priv->inbox_base + SPRD_MBOX_TRIGGER);

 	return 0;
 }

 static int sprd_mbox_flush(struct mbox_chan *chan, unsigned long timeout)
 {
 	struct sprd_mbox_priv *priv = to_sprd_mbox_priv(chan->mbox);
 	unsigned long id = (unsigned long)chan->con_priv;
 	u32 busy;

 	timeout = jiffies + msecs_to_jiffies(timeout);

 	while (time_before(jiffies, timeout)) {
 		busy = readl(priv->inbox_base + SPRD_MBOX_FIFO_STS) &
 			SPRD_INBOX_FIFO_BUSY_MASK;
 		if (!(busy & BIT(id))) {
 			mbox_chan_txdone(chan, 0);
 			return 0;
 		}

 		udelay(1);
 	}

 	return -ETIME;
 }

 static int sprd_mbox_startup(struct mbox_chan *chan)
 {
 	struct sprd_mbox_priv *priv = to_sprd_mbox_priv(chan->mbox);
 	u32 val;

 	mutex_lock(&priv->lock);
 	if (priv->refcnt++ == 0) {
 		/* Select outbox FIFO mode and reset the outbox FIFO status */
 		writel(0x0, priv->outbox_base + SPRD_MBOX_FIFO_RST);

 		/* Enable inbox FIFO overflow and delivery interrupt */
 		val = readl(priv->inbox_base + SPRD_MBOX_IRQ_MSK);
 		val &= ~(SPRD_INBOX_FIFO_OVERFLOW_IRQ | SPRD_INBOX_FIFO_DELIVER_IRQ);
 		writel(val, priv->inbox_base + SPRD_MBOX_IRQ_MSK);

 		/* Enable outbox FIFO not empty interrupt */
 		val = readl(priv->outbox_base + SPRD_MBOX_IRQ_MSK);
 		val &= ~SPRD_OUTBOX_FIFO_NOT_EMPTY_IRQ;
 		writel(val, priv->outbox_base + SPRD_MBOX_IRQ_MSK);

 		/* Enable supplementary outbox as the fundamental one */
 		if (priv->supp_base) {
 			writel(0x0, priv->supp_base + SPRD_MBOX_FIFO_RST);
 			val = readl(priv->supp_base + SPRD_MBOX_IRQ_MSK);
 			val &= ~SPRD_OUTBOX_FIFO_NOT_EMPTY_IRQ;
 			writel(val, priv->supp_base + SPRD_MBOX_IRQ_MSK);
 		}
 	}
 	mutex_unlock(&priv->lock);

 	return 0;
 }

 static void sprd_mbox_shutdown(struct mbox_chan *chan)
 {
 	struct sprd_mbox_priv *priv = to_sprd_mbox_priv(chan->mbox);

 	mutex_lock(&priv->lock);
 	if (--priv->refcnt == 0) {
 		/* Disable inbox & outbox interrupt */
 		writel(SPRD_INBOX_FIFO_IRQ_MASK, priv->inbox_base + SPRD_MBOX_IRQ_MSK);
 		writel(SPRD_OUTBOX_FIFO_IRQ_MASK, priv->outbox_base + SPRD_MBOX_IRQ_MSK);

 		if (priv->supp_base)
 			writel(SPRD_OUTBOX_FIFO_IRQ_MASK,
 			       priv->supp_base + SPRD_MBOX_IRQ_MSK);
 	}
 	mutex_unlock(&priv->lock);
 }

 static const struct mbox_chan_ops sprd_mbox_ops = {
 	.send_data	= sprd_mbox_send_data,
 	.flush		= sprd_mbox_flush,
 	.startup	= sprd_mbox_startup,
 	.shutdown	= sprd_mbox_shutdown,
 };

 static void sprd_mbox_disable(void *data)
 {
 	struct sprd_mbox_priv *priv = data;

 	clk_disable_unprepare(priv->clk);
 }

 static int sprd_mbox_probe(struct platform_device *pdev)
 {
 	struct device *dev = &pdev->dev;
 	struct sprd_mbox_priv *priv;
 	int ret, inbox_irq, outbox_irq, supp_irq;
 	unsigned long id, supp;

 	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
 	if (!priv)
 		return -ENOMEM;

 	priv->dev = dev;
 	mutex_init(&priv->lock);

 	/*
 	 * Unisoc mailbox uses an inbox to send messages to the target
 	 * core, and uses (an) outbox(es) to receive messages from other
 	 * cores.
 	 *
 	 * Thus in general the mailbox controller supplies 2 different
 	 * register addresses and IRQ numbers for inbox and outbox.
 	 *
 	 * If necessary, a supplementary inbox could be enabled optionally
 	 * with an independent FIFO and an extra interrupt.
 	 */
 	priv->inbox_base = devm_platform_ioremap_resource(pdev, 0);
 	if (IS_ERR(priv->inbox_base))
 		return PTR_ERR(priv->inbox_base);

 	priv->outbox_base = devm_platform_ioremap_resource(pdev, 1);
 	if (IS_ERR(priv->outbox_base))
 		return PTR_ERR(priv->outbox_base);

 	priv->clk = devm_clk_get(dev, "enable");
 	if (IS_ERR(priv->clk)) {
 		dev_err(dev, "failed to get mailbox clock\n");
 		return PTR_ERR(priv->clk);
 	}

 	ret = clk_prepare_enable(priv->clk);
 	if (ret)
 		return ret;

 	ret = devm_add_action_or_reset(dev, sprd_mbox_disable, priv);
 	if (ret) {
 		dev_err(dev, "failed to add mailbox disable action\n");
 		return ret;
 	}

 	inbox_irq = platform_get_irq_byname(pdev, "inbox");
 	if (inbox_irq < 0)
 		return inbox_irq;

 	ret = devm_request_irq(dev, inbox_irq, sprd_mbox_inbox_isr,
 			       IRQF_NO_SUSPEND, dev_name(dev), priv);
 	if (ret) {
 		dev_err(dev, "failed to request inbox IRQ: %d\n", ret);
 		return ret;
 	}

 	outbox_irq = platform_get_irq_byname(pdev, "outbox");
 	if (outbox_irq < 0)
 		return outbox_irq;

 	ret = devm_request_irq(dev, outbox_irq, sprd_mbox_outbox_isr,
 			       IRQF_NO_SUSPEND, dev_name(dev), priv);
 	if (ret) {
 		dev_err(dev, "failed to request outbox IRQ: %d\n", ret);
 		return ret;
 	}

 	/* Supplementary outbox IRQ is optional */
 	supp_irq = platform_get_irq_byname(pdev, "supp-outbox");
 	if (supp_irq > 0) {
 		ret = devm_request_irq(dev, supp_irq, sprd_mbox_supp_isr,
 				       IRQF_NO_SUSPEND, dev_name(dev), priv);
 		if (ret) {
 			dev_err(dev, "failed to request outbox IRQ: %d\n", ret);
 			return ret;
 		}

 		supp = (unsigned long) of_device_get_match_data(dev);
 		if (!supp) {
 			dev_err(dev, "no supplementary outbox specified\n");
 			return -ENODEV;
 		}
 		priv->supp_base = priv->outbox_base + (SPRD_OUTBOX_BASE_SPAN * supp);
 	}

 	/* Get the default outbox FIFO depth */
 	priv->outbox_fifo_depth =
 		readl(priv->outbox_base + SPRD_MBOX_FIFO_DEPTH) + 1;
 	priv->mbox.dev = dev;
 	priv->mbox.chans = &priv->chan[0];
 	priv->mbox.num_chans = SPRD_MBOX_CHAN_MAX;
 	priv->mbox.ops = &sprd_mbox_ops;
 	priv->mbox.txdone_irq = true;

 	for (id = 0; id < SPRD_MBOX_CHAN_MAX; id++)
 		priv->chan[id].con_priv = (void *)id;

 	ret = devm_mbox_controller_register(dev, &priv->mbox);
 	if (ret) {
 		dev_err(dev, "failed to register mailbox: %d\n", ret);
 		return ret;
 	}

 	return 0;
 }

 static const struct of_device_id sprd_mbox_of_match[] = {
 	{ .compatible = "sprd,sc9860-mailbox" },
 	{ .compatible = "sprd,sc9863a-mailbox",
 	  .data = (void *)SPRD_SUPP_INBOX_ID_SC9863A },
 	{ },
 };
 MODULE_DEVICE_TABLE(of, sprd_mbox_of_match);

 static struct platform_driver sprd_mbox_driver = {
 	.driver = {
 		.name = "sprd-mailbox",
 		.of_match_table = sprd_mbox_of_match,
 	},
 	.probe	= sprd_mbox_probe,
 };
 module_platform_driver(sprd_mbox_driver);

 MODULE_AUTHOR("Baolin Wang <baolin.wang@unisoc.com>");
 MODULE_DESCRIPTION("Spreadtrum mailbox driver");
 MODULE_LICENSE("GPL v2");
	// SPDX-License-Identifier: GPL-2.0-only
	/*
	* Spreadtrum mailbox driver
	*
	* Copyright (c) 2020 Spreadtrum Communications Inc.
	*/

	#include <linux/delay.h>
	#include <linux/err.h>
	#include <linux/interrupt.h>
	#include <linux/io.h>
	#include <linux/mailbox_controller.h>
	#include <linux/module.h>
	#include <linux/of.h>
	#include <linux/platform_device.h>
	#include <linux/clk.h>

	#define SPRD_MBOX_ID 0x0
	#define SPRD_MBOX_MSG_LOW 0x4
	#define SPRD_MBOX_MSG_HIGH 0x8
	#define SPRD_MBOX_TRIGGER 0xc
	#define SPRD_MBOX_FIFO_RST 0x10
	#define SPRD_MBOX_FIFO_STS 0x14
	#define SPRD_MBOX_IRQ_STS 0x18
	#define SPRD_MBOX_IRQ_MSK 0x1c
	#define SPRD_MBOX_LOCK 0x20
	#define SPRD_MBOX_FIFO_DEPTH 0x24

	/* Bit and mask definition for inbox's SPRD_MBOX_FIFO_STS register */
	#define SPRD_INBOX_FIFO_DELIVER_MASK GENMASK(23, 16)
	#define SPRD_INBOX_FIFO_OVERLOW_MASK GENMASK(15, 8)
	#define SPRD_INBOX_FIFO_DELIVER_SHIFT 16
	#define SPRD_INBOX_FIFO_BUSY_MASK GENMASK(7, 0)

	/* Bit and mask definition for SPRD_MBOX_IRQ_STS register */
	#define SPRD_MBOX_IRQ_CLR BIT(0)

	/* Bit and mask definition for outbox's SPRD_MBOX_FIFO_STS register */
	#define SPRD_OUTBOX_FIFO_FULL BIT(2)
	#define SPRD_OUTBOX_FIFO_WR_SHIFT 16
	#define SPRD_OUTBOX_FIFO_RD_SHIFT 24
	#define SPRD_OUTBOX_FIFO_POS_MASK GENMASK(7, 0)

	/* Bit and mask definition for inbox's SPRD_MBOX_IRQ_MSK register */
	#define SPRD_INBOX_FIFO_BLOCK_IRQ BIT(0)
	#define SPRD_INBOX_FIFO_OVERFLOW_IRQ BIT(1)
	#define SPRD_INBOX_FIFO_DELIVER_IRQ BIT(2)
	#define SPRD_INBOX_FIFO_IRQ_MASK GENMASK(2, 0)

	/* Bit and mask definition for outbox's SPRD_MBOX_IRQ_MSK register */
	#define SPRD_OUTBOX_FIFO_NOT_EMPTY_IRQ BIT(0)
	#define SPRD_OUTBOX_FIFO_IRQ_MASK GENMASK(4, 0)

	#define SPRD_OUTBOX_BASE_SPAN 0x1000
	#define SPRD_MBOX_CHAN_MAX 8
	#define SPRD_SUPP_INBOX_ID_SC9863A 7

	struct sprd_mbox_priv {
	struct mbox_controller mbox;
	struct device *dev;
	void __iomem *inbox_base;
	void __iomem *outbox_base;
	/* Base register address for supplementary outbox */
	void __iomem *supp_base;
	struct clk *clk;
	u32 outbox_fifo_depth;

	struct mutex lock;
	u32 refcnt;
	struct mbox_chan chan[SPRD_MBOX_CHAN_MAX];
	};

	static struct sprd_mbox_priv to_sprd_mbox_priv(struct mbox_controller mbox)
	{
	return container_of(mbox, struct sprd_mbox_priv, mbox);
	}

	static u32 sprd_mbox_get_fifo_len(struct sprd_mbox_priv *priv, u32 fifo_sts)
	{
	u32 wr_pos = (fifo_sts >> SPRD_OUTBOX_FIFO_WR_SHIFT) &
	SPRD_OUTBOX_FIFO_POS_MASK;
	u32 rd_pos = (fifo_sts >> SPRD_OUTBOX_FIFO_RD_SHIFT) &
	SPRD_OUTBOX_FIFO_POS_MASK;
	u32 fifo_len;

	/*
	* If the read pointer is equal with write pointer, which means the fifo
	* is full or empty.
	*/
	if (wr_pos == rd_pos) {
	if (fifo_sts & SPRD_OUTBOX_FIFO_FULL)
	fifo_len = priv->outbox_fifo_depth;
	else
	fifo_len = 0;
	} else if (wr_pos > rd_pos) {
	fifo_len = wr_pos - rd_pos;
	} else {
	fifo_len = priv->outbox_fifo_depth - rd_pos + wr_pos;
	}

	return fifo_len;
	}

	static irqreturn_t do_outbox_isr(void __iomem base, struct sprd_mbox_priv priv)
	{
	struct mbox_chan *chan;
	u32 fifo_sts, fifo_len, msg[2];
	int i, id;

	fifo_sts = readl(base + SPRD_MBOX_FIFO_STS);

	fifo_len = sprd_mbox_get_fifo_len(priv, fifo_sts);
	if (!fifo_len) {
	dev_warn_ratelimited(priv->dev, "spurious outbox interrupt\n");
	return IRQ_NONE;
	}

	for (i = 0; i < fifo_len; i++) {
	msg[0] = readl(base + SPRD_MBOX_MSG_LOW);
	msg[1] = readl(base + SPRD_MBOX_MSG_HIGH);
	id = readl(base + SPRD_MBOX_ID);

	chan = &priv->chan[id];
	if (chan->cl)
	mbox_chan_received_data(chan, (void *)msg);
	else
	dev_warn_ratelimited(priv->dev,
	"message's been dropped at ch[%d]\n", id);

	/* Trigger to update outbox FIFO pointer */
	writel(0x1, base + SPRD_MBOX_TRIGGER);
	}

	/* Clear irq status after reading all message. */
	writel(SPRD_MBOX_IRQ_CLR, base + SPRD_MBOX_IRQ_STS);

	return IRQ_HANDLED;
	}

	static irqreturn_t sprd_mbox_outbox_isr(int irq, void *data)
	{
	struct sprd_mbox_priv *priv = data;

	return do_outbox_isr(priv->outbox_base, priv);
	}

	static irqreturn_t sprd_mbox_supp_isr(int irq, void *data)
	{
	struct sprd_mbox_priv *priv = data;

	return do_outbox_isr(priv->supp_base, priv);
	}

	static irqreturn_t sprd_mbox_inbox_isr(int irq, void *data)
	{
	struct sprd_mbox_priv *priv = data;
	struct mbox_chan *chan;
	u32 fifo_sts, send_sts, busy, id;

	fifo_sts = readl(priv->inbox_base + SPRD_MBOX_FIFO_STS);

	/* Get the inbox data delivery status */
	send_sts = (fifo_sts & SPRD_INBOX_FIFO_DELIVER_MASK) >>
	SPRD_INBOX_FIFO_DELIVER_SHIFT;
	if (!send_sts) {
	dev_warn_ratelimited(priv->dev, "spurious inbox interrupt\n");
	return IRQ_NONE;
	}

	while (send_sts) {
	id = __ffs(send_sts);
	send_sts &= (send_sts - 1);

	chan = &priv->chan[id];

	/*
	* Check if the message was fetched by remote target, if yes,
	* that means the transmission has been completed.
	*/
	busy = fifo_sts & SPRD_INBOX_FIFO_BUSY_MASK;
	if (!(busy & BIT(id)))
	mbox_chan_txdone(chan, 0);
	}

	/* Clear FIFO delivery and overflow status */
	writel(fifo_sts &
	(SPRD_INBOX_FIFO_DELIVER_MASK \| SPRD_INBOX_FIFO_OVERLOW_MASK),
	priv->inbox_base + SPRD_MBOX_FIFO_RST);

	/* Clear irq status */
	writel(SPRD_MBOX_IRQ_CLR, priv->inbox_base + SPRD_MBOX_IRQ_STS);

	return IRQ_HANDLED;
	}

	static int sprd_mbox_send_data(struct mbox_chan chan, void msg)
	{
	struct sprd_mbox_priv *priv = to_sprd_mbox_priv(chan->mbox);
	unsigned long id = (unsigned long)chan->con_priv;
	u32 *data = msg;

	/* Write data into inbox FIFO, and only support 8 bytes every time */
	writel(data[0], priv->inbox_base + SPRD_MBOX_MSG_LOW);
	writel(data[1], priv->inbox_base + SPRD_MBOX_MSG_HIGH);

	/* Set target core id */
	writel(id, priv->inbox_base + SPRD_MBOX_ID);

	/* Trigger remote request */
	writel(0x1, priv->inbox_base + SPRD_MBOX_TRIGGER);

	return 0;
	}

	static int sprd_mbox_flush(struct mbox_chan *chan, unsigned long timeout)
	{
	struct sprd_mbox_priv *priv = to_sprd_mbox_priv(chan->mbox);
	unsigned long id = (unsigned long)chan->con_priv;
	u32 busy;

	timeout = jiffies + msecs_to_jiffies(timeout);

	while (time_before(jiffies, timeout)) {
	busy = readl(priv->inbox_base + SPRD_MBOX_FIFO_STS) &
	SPRD_INBOX_FIFO_BUSY_MASK;
	if (!(busy & BIT(id))) {
	mbox_chan_txdone(chan, 0);
	return 0;
	}

	udelay(1);
	}

	return -ETIME;
	}

	static int sprd_mbox_startup(struct mbox_chan *chan)
	{
	struct sprd_mbox_priv *priv = to_sprd_mbox_priv(chan->mbox);
	u32 val;

	mutex_lock(&priv->lock);
	if (priv->refcnt++ == 0) {
	/* Select outbox FIFO mode and reset the outbox FIFO status */
	writel(0x0, priv->outbox_base + SPRD_MBOX_FIFO_RST);

	/* Enable inbox FIFO overflow and delivery interrupt */
	val = readl(priv->inbox_base + SPRD_MBOX_IRQ_MSK);
	val &= ~(SPRD_INBOX_FIFO_OVERFLOW_IRQ \| SPRD_INBOX_FIFO_DELIVER_IRQ);
	writel(val, priv->inbox_base + SPRD_MBOX_IRQ_MSK);

	/* Enable outbox FIFO not empty interrupt */
	val = readl(priv->outbox_base + SPRD_MBOX_IRQ_MSK);
	val &= ~SPRD_OUTBOX_FIFO_NOT_EMPTY_IRQ;
	writel(val, priv->outbox_base + SPRD_MBOX_IRQ_MSK);

	/* Enable supplementary outbox as the fundamental one */
	if (priv->supp_base) {
	writel(0x0, priv->supp_base + SPRD_MBOX_FIFO_RST);
	val = readl(priv->supp_base + SPRD_MBOX_IRQ_MSK);
	val &= ~SPRD_OUTBOX_FIFO_NOT_EMPTY_IRQ;
	writel(val, priv->supp_base + SPRD_MBOX_IRQ_MSK);
	}
	}
	mutex_unlock(&priv->lock);

	return 0;
	}

	static void sprd_mbox_shutdown(struct mbox_chan *chan)
	{
	struct sprd_mbox_priv *priv = to_sprd_mbox_priv(chan->mbox);

	mutex_lock(&priv->lock);
	if (--priv->refcnt == 0) {
	/* Disable inbox & outbox interrupt */
	writel(SPRD_INBOX_FIFO_IRQ_MASK, priv->inbox_base + SPRD_MBOX_IRQ_MSK);
	writel(SPRD_OUTBOX_FIFO_IRQ_MASK, priv->outbox_base + SPRD_MBOX_IRQ_MSK);

	if (priv->supp_base)
	writel(SPRD_OUTBOX_FIFO_IRQ_MASK,
	priv->supp_base + SPRD_MBOX_IRQ_MSK);
	}
	mutex_unlock(&priv->lock);
	}

	static const struct mbox_chan_ops sprd_mbox_ops = {
	.send_data = sprd_mbox_send_data,
	.flush = sprd_mbox_flush,
	.startup = sprd_mbox_startup,
	.shutdown = sprd_mbox_shutdown,
	};

	static void sprd_mbox_disable(void *data)
	{
	struct sprd_mbox_priv *priv = data;

	clk_disable_unprepare(priv->clk);
	}

	static int sprd_mbox_probe(struct platform_device *pdev)
	{
	struct device *dev = &pdev->dev;
	struct sprd_mbox_priv *priv;
	int ret, inbox_irq, outbox_irq, supp_irq;
	unsigned long id, supp;

	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
	if (!priv)
	return -ENOMEM;

	priv->dev = dev;
	mutex_init(&priv->lock);

	/*
	* Unisoc mailbox uses an inbox to send messages to the target
	* core, and uses (an) outbox(es) to receive messages from other
	* cores.
	*
	* Thus in general the mailbox controller supplies 2 different
	* register addresses and IRQ numbers for inbox and outbox.
	*
	* If necessary, a supplementary inbox could be enabled optionally
	* with an independent FIFO and an extra interrupt.
	*/
	priv->inbox_base = devm_platform_ioremap_resource(pdev, 0);
	if (IS_ERR(priv->inbox_base))
	return PTR_ERR(priv->inbox_base);

	priv->outbox_base = devm_platform_ioremap_resource(pdev, 1);
	if (IS_ERR(priv->outbox_base))
	return PTR_ERR(priv->outbox_base);

	priv->clk = devm_clk_get(dev, "enable");
	if (IS_ERR(priv->clk)) {
	dev_err(dev, "failed to get mailbox clock\n");
	return PTR_ERR(priv->clk);
	}

	ret = clk_prepare_enable(priv->clk);
	if (ret)
	return ret;

	ret = devm_add_action_or_reset(dev, sprd_mbox_disable, priv);
	if (ret) {
	dev_err(dev, "failed to add mailbox disable action\n");
	return ret;
	}

	inbox_irq = platform_get_irq_byname(pdev, "inbox");
	if (inbox_irq < 0)
	return inbox_irq;

	ret = devm_request_irq(dev, inbox_irq, sprd_mbox_inbox_isr,
	IRQF_NO_SUSPEND, dev_name(dev), priv);
	if (ret) {
	dev_err(dev, "failed to request inbox IRQ: %d\n", ret);
	return ret;
	}

	outbox_irq = platform_get_irq_byname(pdev, "outbox");
	if (outbox_irq < 0)
	return outbox_irq;

	ret = devm_request_irq(dev, outbox_irq, sprd_mbox_outbox_isr,
	IRQF_NO_SUSPEND, dev_name(dev), priv);
	if (ret) {
	dev_err(dev, "failed to request outbox IRQ: %d\n", ret);
	return ret;
	}

	/* Supplementary outbox IRQ is optional */
	supp_irq = platform_get_irq_byname(pdev, "supp-outbox");
	if (supp_irq > 0) {
	ret = devm_request_irq(dev, supp_irq, sprd_mbox_supp_isr,
	IRQF_NO_SUSPEND, dev_name(dev), priv);
	if (ret) {
	dev_err(dev, "failed to request outbox IRQ: %d\n", ret);
	return ret;
	}

	supp = (unsigned long) of_device_get_match_data(dev);
	if (!supp) {
	dev_err(dev, "no supplementary outbox specified\n");
	return -ENODEV;
	}
	priv->supp_base = priv->outbox_base + (SPRD_OUTBOX_BASE_SPAN * supp);
	}

	/* Get the default outbox FIFO depth */
	priv->outbox_fifo_depth =
	readl(priv->outbox_base + SPRD_MBOX_FIFO_DEPTH) + 1;
	priv->mbox.dev = dev;
	priv->mbox.chans = &priv->chan[0];
	priv->mbox.num_chans = SPRD_MBOX_CHAN_MAX;
	priv->mbox.ops = &sprd_mbox_ops;
	priv->mbox.txdone_irq = true;

	for (id = 0; id < SPRD_MBOX_CHAN_MAX; id++)
	priv->chan[id].con_priv = (void *)id;

	ret = devm_mbox_controller_register(dev, &priv->mbox);
	if (ret) {
	dev_err(dev, "failed to register mailbox: %d\n", ret);
	return ret;
	}

	return 0;
	}

	static const struct of_device_id sprd_mbox_of_match[] = {
	{ .compatible = "sprd,sc9860-mailbox" },
	{ .compatible = "sprd,sc9863a-mailbox",
	.data = (void *)SPRD_SUPP_INBOX_ID_SC9863A },
	{ },
	};
	MODULE_DEVICE_TABLE(of, sprd_mbox_of_match);

	static struct platform_driver sprd_mbox_driver = {
	.driver = {
	.name = "sprd-mailbox",
	.of_match_table = sprd_mbox_of_match,
	},
	.probe = sprd_mbox_probe,
	};
	module_platform_driver(sprd_mbox_driver);

	MODULE_AUTHOR("Baolin Wang <baolin.wang@unisoc.com>");
	MODULE_DESCRIPTION("Spreadtrum mailbox driver");
	MODULE_LICENSE("GPL v2");