Date:   Fri, 27 Oct 2017 14:15:03 +0800
From:   Kaihua Zhong <zhongkaihua@...wei.com>
To:     <robh+dt@...nel.org>, <mark.rutland@....com>,
        <xuwei5@...ilicon.com>, <catalin.marinas@....com>,
        <will.deacon@....com>, <jassisinghbrar@...il.com>
CC:     <devicetree@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>, <guodong.xu@...aro.org>,
        <haojian.zhuang@...aro.org>, <suzhuangluan@...ilicon.com>,
        <xuezhiliang@...ilicon.com>, <kevin.wangtao@...ilicon.com>,
        <zhongkaihua@...wei.com>
Subject: [PATCH v2 2/3] mailbox: Add support for Hi3660 mailbox

Hi3660 mailbox controller is used to send message within multiple
processors, MCU, HIFI, etc.  It supports 32 mailbox channels and every
channel can only be used for single transferring direction.  Once the
channel is enabled, it needs to specify the destination interrupt and
acknowledge interrupt, these two interrupt vectors are used to create
the connection between the mailbox and interrupt controllers.

The application processor (or from point of view of kernel) is not the
only one master which can launch the data transferring, other
processors or MCU/DSP also can kick off the data transferring.  So this
driver implements a locking mechanism to support exclusive accessing.

The data transferring supports two modes, one is named as "automatic
acknowledge" mode so after send message the kernel doesn't need to wait
for acknowledge from remote and directly return; there have another mode
is to rely on handling interrupt for acknowledge.

This commit is for initial version driver, which only supports
"automatic acknowledge" mode to support CPU clock, which is the only
one consumer to use mailbox and has been verified.  Later may enhance
this driver for interrupt mode (e.g. for supporting HIFI).

Cc: John Stultz <john.stultz@...aro.org>
Cc: Guodong Xu <guodong.xu@...aro.org>
Cc: Haojian Zhuang <haojian.zhuang@...aro.org>
Cc: Niranjan Yadla <nyadla@...ence.com>
Cc: Raj Pawate <pawateb@...ence.com>
Signed-off-by: Leo Yan <leo.yan@...aro.org>
Signed-off-by: Ruyi Wang <wangruyi@...wei.com>
Signed-off-by: Kaihua Zhong <zhongkaihua@...wei.com>
Signed-off-by: Kevin Wang <kevin.wangtao@...ilicon.com>
---
 drivers/mailbox/Kconfig          |   8 +
 drivers/mailbox/Makefile         |   2 +
 drivers/mailbox/hi3660-mailbox.c | 331 +++++++++++++++++++++++++++++++++++++++
 3 files changed, 341 insertions(+)
 create mode 100644 drivers/mailbox/hi3660-mailbox.c

diff --git a/drivers/mailbox/Kconfig b/drivers/mailbox/Kconfig
index c5731e5..4b5d6e9 100644
--- a/drivers/mailbox/Kconfig
+++ b/drivers/mailbox/Kconfig
@@ -108,6 +108,14 @@ config TI_MESSAGE_MANAGER
 	  multiple processors within the SoC. Select this driver if your
 	  platform has support for the hardware block.
 
+config HI3660_MBOX
+	tristate "Hi3660 Mailbox"
+	depends on ARCH_HISI && OF
+	help
+	  An implementation of the hi3660 mailbox. It is used to send message
+	  between application processors and other processors/MCU/DSP. Select
+	  Y here if you want to use Hi3660 mailbox controller.
+
 config HI6220_MBOX
 	tristate "Hi6220 Mailbox"
 	depends on ARCH_HISI
diff --git a/drivers/mailbox/Makefile b/drivers/mailbox/Makefile
index d54e412..7d1bd51 100644
--- a/drivers/mailbox/Makefile
+++ b/drivers/mailbox/Makefile
@@ -26,6 +26,8 @@ obj-$(CONFIG_TI_MESSAGE_MANAGER) += ti-msgmgr.o
 
 obj-$(CONFIG_XGENE_SLIMPRO_MBOX) += mailbox-xgene-slimpro.o
 
+obj-$(CONFIG_HI3660_MBOX)	+= hi3660-mailbox.o
+
 obj-$(CONFIG_HI6220_MBOX)	+= hi6220-mailbox.o
 
 obj-$(CONFIG_BCM_PDC_MBOX)	+= bcm-pdc-mailbox.o
diff --git a/drivers/mailbox/hi3660-mailbox.c b/drivers/mailbox/hi3660-mailbox.c
new file mode 100644
index 0000000..67df8f8
--- /dev/null
+++ b/drivers/mailbox/hi3660-mailbox.c
@@ -0,0 +1,331 @@
+/*
+ * Hisilicon's Hi3660 mailbox controller driver
+ *
+ * Copyright (c) 2017 Hisilicon Limited.
+ * Copyright (c) 2017 Linaro Limited.
+ *
+ * Author: Leo Yan <leo.yan@...aro.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/bitops.h>
+#include <linux/delay.h>
+#include <linux/device.h>
+#include <linux/err.h>
+#include <linux/interrupt.h>
+#include <linux/io.h>
+#include <linux/iopoll.h>
+#include <linux/mailbox_controller.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/slab.h>
+
+#include "mailbox.h"
+
+#define MBOX_CHAN_MAX			32
+
+#define MBOX_RX				(0x0)
+#define MBOX_TX				(0x1)
+
+#define MBOX_BASE(mbox, ch)		((mbox)->base + ((ch) * 0x40))
+#define MBOX_SRC_REG			(0x00)
+#define MBOX_DST_REG			(0x04)
+#define MBOX_DCLR_REG			(0x08)
+#define MBOX_DSTAT_REG			(0x0c)
+#define MBOX_MODE_REG			(0x10)
+#define MBOX_IMASK_REG			(0x14)
+#define MBOX_ICLR_REG			(0x18)
+#define MBOX_SEND_REG			(0x1c)
+#define MBOX_DATA_REG			(0x20)
+
+#define MBOX_IPC_LOCK_REG		(0xa00)
+#define MBOX_IPC_UNLOCK			(0x1acce551)
+
+#define MBOX_AUTOMATIC_ACK		(1)
+
+#define MBOX_STATE_IDLE			BIT(4)
+#define MBOX_STATE_ACK			BIT(7)
+
+#define MBOX_MSG_LEN			8
+
+/**
+ * Hi3660 mailbox channel device data
+ *
+ * A channel can be used for TX or RX, it can trigger remote
+ * processor interrupt to notify remote processor and can receive
+ * interrupt if has incoming message.
+ *
+ * @dst_irq:	Interrupt vector for remote processor
+ * @ack_irq:	Interrupt vector for local processor
+ */
+struct hi3660_mbox_dev {
+	unsigned int dst_irq;
+	unsigned int ack_irq;
+};
+
+/**
+ * Hi3660 mailbox controller data
+ *
+ * Mailbox controller includes 32 channels and can allocate
+ * channel for message transferring.
+ *
+ * @dev:	Device to which it is attached
+ * @base:	Base address of the register mapping region
+ * @chan:	Representation of channels in mailbox controller
+ * @mdev:	Representation of channel device data
+ * @controller:	Representation of a communication channel controller
+ */
+struct hi3660_mbox {
+	struct device *dev;
+	void __iomem *base;
+	struct mbox_chan chan[MBOX_CHAN_MAX];
+	struct hi3660_mbox_dev mdev[MBOX_CHAN_MAX];
+	struct mbox_controller controller;
+};
+
+static inline struct hi3660_mbox *to_hi3660_mbox(struct mbox_chan *chan)
+{
+	return container_of(chan->mbox, struct hi3660_mbox, controller);
+}
+
+static int hi3660_mbox_check_state(struct mbox_chan *chan)
+{
+	unsigned long ch = (unsigned long)chan->con_priv;
+	struct hi3660_mbox *mbox = to_hi3660_mbox(chan);
+	struct hi3660_mbox_dev *mdev = &mbox->mdev[ch];
+	void __iomem *base = MBOX_BASE(mbox, ch);
+	unsigned long val;
+	unsigned int state, ret;
+
+	/* Mailbox is idle so directly bail out */
+	state = readl_relaxed(base + MBOX_MODE_REG);
+	if (state & MBOX_STATE_IDLE)
+		return 0;
+
+	/* Wait for acknowledge from remote */
+	ret = readx_poll_timeout_atomic(readl_relaxed, base + MBOX_MODE_REG,
+			val, (val & MBOX_STATE_ACK), 1000, 300000);
+	if (ret) {
+		dev_err(mbox->dev, "%s: timeout for receiving ack\n", __func__);
+		return ret;
+	}
+
+	/* Ensure channel is released */
+	writel_relaxed(0xffffffff, base + MBOX_IMASK_REG);
+	writel_relaxed(BIT(mdev->ack_irq), base + MBOX_SRC_REG);
+	__asm__ volatile ("sev");
+	return 0;
+}
+
+static int hi3660_mbox_unlock(struct mbox_chan *chan)
+{
+	struct hi3660_mbox *mbox = to_hi3660_mbox(chan);
+	unsigned int val, retry = 3;
+
+	do {
+		writel_relaxed(MBOX_IPC_UNLOCK, mbox->base + MBOX_IPC_LOCK_REG);
+
+		val = readl_relaxed(mbox->base + MBOX_IPC_LOCK_REG);
+		if (!val)
+			break;
+
+		udelay(10);
+	} while (retry--);
+
+	return (!val) ? 0 : -ETIMEDOUT;
+}
+
+static int hi3660_mbox_acquire_channel(struct mbox_chan *chan)
+{
+	unsigned long ch = (unsigned long)chan->con_priv;
+	struct hi3660_mbox *mbox = to_hi3660_mbox(chan);
+	struct hi3660_mbox_dev *mdev = &mbox->mdev[ch];
+	void __iomem *base = MBOX_BASE(mbox, ch);
+	unsigned int val = 0, retry = 10;
+
+	/*
+	 * Hardware locking for exclusive accessing within CPUs
+	 * without exclusive monitor mechanism.
+	 */
+	do {
+		val = readl_relaxed(base + MBOX_MODE_REG);
+		if (!(val & MBOX_STATE_IDLE)) {
+			__asm__ volatile ("wfe");
+			continue;
+		}
+
+		/* Check if channel has be acquired */
+		writel_relaxed(BIT(mdev->ack_irq), base + MBOX_SRC_REG);
+		val = readl_relaxed(base + MBOX_SRC_REG) & BIT(mdev->ack_irq);
+		if (val)
+			break;
+
+	} while (retry--);
+
+	return (val) ? 0 : -ETIMEDOUT;
+}
+
+static int hi3660_mbox_send(struct mbox_chan *chan, u32 *msg)
+{
+	unsigned long ch = (unsigned long)chan->con_priv;
+	struct hi3660_mbox *mbox = to_hi3660_mbox(chan);
+	struct hi3660_mbox_dev *mdev = &mbox->mdev[ch];
+	void __iomem *base = MBOX_BASE(mbox, ch);
+	unsigned int i;
+
+	/* Clear mask for destination interrupt */
+	writel_relaxed(~BIT(mdev->dst_irq), base + MBOX_IMASK_REG);
+
+	/* Config destination for interrupt vector */
+	writel_relaxed(BIT(mdev->dst_irq), base + MBOX_DST_REG);
+
+	/* Automatic acknowledge mode */
+	writel_relaxed(MBOX_AUTOMATIC_ACK, base + MBOX_MODE_REG);
+
+	/* Fill message data */
+	for (i = 0; i < MBOX_MSG_LEN; i++)
+		writel_relaxed(msg[i], base + MBOX_DATA_REG + i * 4);
+
+	/* Trigger data transferring */
+	writel_relaxed(BIT(mdev->ack_irq), base + MBOX_SEND_REG);
+	return 0;
+}
+
+static int hi3660_mbox_send_data(struct mbox_chan *chan, void *msg)
+{
+	struct hi3660_mbox *mbox = to_hi3660_mbox(chan);
+	int err;
+
+	err = hi3660_mbox_check_state(chan);
+	if (err) {
+		dev_err(mbox->dev, "checking state failed\n");
+		return err;
+	}
+
+	err = hi3660_mbox_unlock(chan);
+	if (err) {
+		dev_err(mbox->dev, "unlocking mailbox failed\n");
+		return err;
+	}
+
+	err = hi3660_mbox_acquire_channel(chan);
+	if (err) {
+		dev_err(mbox->dev, "acquiring channel failed\n");
+		return err;
+	}
+
+	return hi3660_mbox_send(chan, msg);
+}
+
+static struct mbox_chan_ops hi3660_mbox_ops = {
+	.send_data    = hi3660_mbox_send_data,
+};
+
+static struct mbox_chan *hi3660_mbox_xlate(struct mbox_controller *controller,
+					   const struct of_phandle_args *spec)
+{
+	struct hi3660_mbox *mbox = dev_get_drvdata(controller->dev);
+	struct hi3660_mbox_dev *mdev;
+	unsigned int ch = spec->args[0];
+
+	if (ch >= MBOX_CHAN_MAX) {
+		dev_err(mbox->dev, "Invalid channel idx %d\n", ch);
+		return ERR_PTR(-EINVAL);
+	}
+
+	mdev = &mbox->mdev[ch];
+	mdev->dst_irq = spec->args[1];
+	mdev->ack_irq = spec->args[2];
+
+	return &mbox->chan[ch];
+}
+
+static const struct of_device_id hi3660_mbox_of_match[] = {
+	{ .compatible = "hisilicon,hi3660-mbox", },
+	{},
+};
+
+MODULE_DEVICE_TABLE(of, hi3660_mbox_of_match);
+
+static int hi3660_mbox_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct hi3660_mbox *mbox;
+	struct mbox_chan *chan;
+	struct resource *res;
+	unsigned long ch;
+	int err;
+
+	mbox = devm_kzalloc(dev, sizeof(*mbox), GFP_KERNEL);
+	if (!mbox)
+		return -ENOMEM;
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	mbox->base = devm_ioremap_resource(dev, res);
+	if (IS_ERR(mbox->base))
+		return PTR_ERR(mbox->base);
+
+	mbox->dev = dev;
+	mbox->controller.dev = dev;
+	mbox->controller.chans = mbox->chan;
+	mbox->controller.num_chans = MBOX_CHAN_MAX;
+	mbox->controller.ops = &hi3660_mbox_ops;
+	mbox->controller.of_xlate = hi3660_mbox_xlate;
+
+	/* Initialize mailbox channel data */
+	chan = mbox->chan;
+	for (ch = 0; ch < MBOX_CHAN_MAX; ch++)
+		chan[ch].con_priv = (void *)ch;
+
+	err = mbox_controller_register(&mbox->controller);
+	if (err) {
+		dev_err(dev, "Failed to register mailbox %d\n", err);
+		return err;
+	}
+
+	platform_set_drvdata(pdev, mbox);
+	dev_info(dev, "Mailbox enabled\n");
+	return 0;
+}
+
+static int hi3660_mbox_remove(struct platform_device *pdev)
+{
+	struct hi3660_mbox *mbox = platform_get_drvdata(pdev);
+
+	mbox_controller_unregister(&mbox->controller);
+	return 0;
+}
+
+static struct platform_driver hi3660_mbox_driver = {
+	.probe  = hi3660_mbox_probe,
+	.remove = hi3660_mbox_remove,
+	.driver = {
+		.name = "hi3660-mbox",
+		.of_match_table = hi3660_mbox_of_match,
+	},
+};
+
+static int __init hi3660_mbox_init(void)
+{
+	return platform_driver_register(&hi3660_mbox_driver);
+}
+core_initcall(hi3660_mbox_init);
+
+static void __exit hi3660_mbox_exit(void)
+{
+	platform_driver_unregister(&hi3660_mbox_driver);
+}
+module_exit(hi3660_mbox_exit);
+
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("Hisilicon Hi3660 Mailbox Controller");
+MODULE_AUTHOR("Leo Yan <leo.yan@...aro.org>");
-- 
1.9.1

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