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From:   Baolin Wang <baolin.wang7@gmail.com>
To:     robh+dt@kernel.org, mark.rutland@arm.com, jassisinghbrar@gmail.com
Cc:     orsonzhai@gmail.com, zhang.lyra@gmail.com, baolin.wang7@gmail.com,
        devicetree@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: [PATCH v2 2/2] mailbox: sprd: Add Spreadtrum mailbox driver
Date:   Mon, 23 Mar 2020 14:13:47 +0800
Message-Id: <3387181f33b841851fce4e648cfae95d69882cae.1584943873.git.baolin.wang7@gmail.com>
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From: Baolin Wang <baolin.wang@unisoc.com>

The Spreadtrum mailbox controller supports 8 channels to communicate
with MCUs, and it contains 2 different parts: inbox and outbox, which
are used to send and receive messages by IRQ mode.

Signed-off-by: Baolin Wang <baolin.wang@unisoc.com>
Signed-off-by: Baolin Wang <baolin.wang7@gmail.com>
---
Changes from v1:
 - None
---
 drivers/mailbox/Kconfig        |   8 +
 drivers/mailbox/Makefile       |   2 +
 drivers/mailbox/sprd-mailbox.c | 350 +++++++++++++++++++++++++++++++++++++++++
 3 files changed, 360 insertions(+)
 create mode 100644 drivers/mailbox/sprd-mailbox.c

diff --git a/drivers/mailbox/Kconfig b/drivers/mailbox/Kconfig
index ab4eb75..a33eaab 100644
--- a/drivers/mailbox/Kconfig
+++ b/drivers/mailbox/Kconfig
@@ -227,4 +227,12 @@ config ZYNQMP_IPI_MBOX
 	  message to the IPI buffer and will access the IPI control
 	  registers to kick the other processor or enquire status.
 
+config SPRD_MBOX
+	tristate "Spreadtrum Mailbox"
+	depends on ARCH_SPRD || COMPILE_TEST
+	help
+	  Mailbox driver implementation for the Spreadtrum platform. It is used
+	  to send message between application processors and MCU. Say Y here if
+	  you want to build the Spreatrum mailbox controller driver.
+
 endif
diff --git a/drivers/mailbox/Makefile b/drivers/mailbox/Makefile
index c22fad6..0f47b6b 100644
--- a/drivers/mailbox/Makefile
+++ b/drivers/mailbox/Makefile
@@ -48,3 +48,5 @@ obj-$(CONFIG_STM32_IPCC) 	+= stm32-ipcc.o
 obj-$(CONFIG_MTK_CMDQ_MBOX)	+= mtk-cmdq-mailbox.o
 
 obj-$(CONFIG_ZYNQMP_IPI_MBOX)	+= zynqmp-ipi-mailbox.o
+
+obj-$(CONFIG_SPRD_MBOX)		+= sprd-mailbox.o
diff --git a/drivers/mailbox/sprd-mailbox.c b/drivers/mailbox/sprd-mailbox.c
new file mode 100644
index 0000000..58e5388
--- /dev/null
+++ b/drivers/mailbox/sprd-mailbox.c
@@ -0,0 +1,350 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Spreadtrum mailbox driver
+ *
+ * Copyright (c) 2020 Spreadtrum Communications Inc.
+ */
+
+#include <linux/err.h>
+#include <linux/interrupt.h>
+#include <linux/io.h>
+#include <linux/mailbox_controller.h>
+#include <linux/module.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 definiation 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 definiation for SPRD_MBOX_IRQ_STS register */
+#define SPRD_MBOX_IRQ_CLR			BIT(0)
+
+/* Bit and mask definiation for outbox's SPRD_MBOX_FIFO_STS register */
+#define SPRD_OUTBOX_FIFO_FULL			BIT(0)
+#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 definiation 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 definiation 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_MBOX_CHAN_MAX			8
+
+struct sprd_mbox_chan {
+	u8			id;
+	struct mbox_chan	*chan;
+};
+
+struct sprd_mbox_priv {
+	struct mbox_controller	mbox;
+	struct device		*dev;
+	void __iomem		*inbox_base;
+	void __iomem		*outbox_base;
+	struct clk		*clk;
+	u32			outbox_fifo_depth;
+
+	struct sprd_mbox_chan	mchan[SPRD_MBOX_CHAN_MAX];
+	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 sprd_mbox_outbox_isr(int irq, void *data)
+{
+	struct sprd_mbox_priv *priv = data;
+	struct sprd_mbox_chan *mchan;
+	u32 fifo_sts, fifo_len, msg[2];
+	int i, id;
+
+	fifo_sts = readl(priv->outbox_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(priv->outbox_base + SPRD_MBOX_MSG_LOW);
+		msg[1] = readl(priv->outbox_base + SPRD_MBOX_MSG_HIGH);
+		id = readl(priv->outbox_base + SPRD_MBOX_ID);
+
+		mchan = &priv->mchan[id];
+		mbox_chan_received_data(mchan->chan, (void *)msg);
+
+		/* Trigger to update outbox FIFO pointer */
+		writel(0x1, priv->outbox_base + SPRD_MBOX_TRIGGER);
+	}
+
+	/* Clear irq status after reading all message. */
+	writel(SPRD_MBOX_IRQ_CLR, priv->outbox_base + SPRD_MBOX_IRQ_STS);
+
+	return IRQ_HANDLED;
+}
+
+static irqreturn_t sprd_mbox_inbox_isr(int irq, void *data)
+{
+	struct sprd_mbox_priv *priv = data;
+	struct sprd_mbox_chan *mchan;
+	u32 fifo_sts, send_sts, 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);
+
+		mchan = &priv->mchan[id];
+		mbox_chan_txdone(mchan->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);
+	struct sprd_mbox_chan *mchan = chan->con_priv;
+	u32 *data = msg, busy;
+
+	/*
+	 * Check if current channel is busy or not, and we can not send data
+	 * if current channel is busy.
+	 */
+	busy = readl(priv->inbox_base + SPRD_MBOX_FIFO_STS) &
+		SPRD_INBOX_FIFO_BUSY_MASK;
+	if (busy & BIT(mchan->id)) {
+		dev_err(priv->dev, "Channel %d is busy\n", mchan->id);
+		return -EBUSY;
+	}
+
+	/* 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(mchan->id, priv->inbox_base + SPRD_MBOX_ID);
+
+	/* Trigger remote request */
+	writel(0x1, priv->inbox_base + SPRD_MBOX_TRIGGER);
+
+	return 0;
+}
+
+static int sprd_mbox_startup(struct mbox_chan *chan)
+{
+	struct sprd_mbox_priv *priv = to_sprd_mbox_priv(chan->mbox);
+	u32 val;
+
+	/* 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);
+
+	return 0;
+}
+
+static void sprd_mbox_shutdown(struct mbox_chan *chan)
+{
+	struct sprd_mbox_priv *priv = to_sprd_mbox_priv(chan->mbox);
+
+	/* 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);
+}
+
+static const struct mbox_chan_ops sprd_mbox_ops = {
+	.send_data    = sprd_mbox_send_data,
+	.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 i, ret, inbox_irq, outbox_irq;
+
+	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
+	if (!priv)
+		return -ENOMEM;
+
+	priv->dev = dev;
+
+	/*
+	 * The Spreadtrum mailbox uses an inbox to send messages to the target
+	 * core, and uses an outbox to receive messages from other cores.
+	 *
+	 * Thus the mailbox controller supplies 2 different register addresses
+	 * and IRQ numbers for inbox and outbox.
+	 */
+	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(pdev, 0);
+	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(pdev, 1);
+	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;
+	}
+
+	/* 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 (i = 0; i < SPRD_MBOX_CHAN_MAX; i++) {
+		priv->chan[i].con_priv = &priv->mchan[i];
+
+		priv->mchan[i].chan = &priv->chan[i];
+		priv->mchan[i].id = i;
+	}
+
+	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", },
+	{ },
+};
+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");
-- 
1.9.1