mailbox: Add Platform Message-Handling-Unit variant driver

Add Message-Handling-Unit driver for platform variants as mailbox controller.
Actually, only the Amlogic Meson GXBB SoC MHU is supported.

Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
Signed-off-by: Jassi Brar <jaswinder.singh@linaro.org>

drivers/mailbox/Kconfig

@@ -15,6 +15,16 @@ config ARM_MHU
 	  The controller has 3 mailbox channels, the last of which can be
 	  used in Secure mode only.
 
+config PLATFORM_MHU
+	tristate "Platform MHU Mailbox"
+	depends on OF
+	depends on HAS_IOMEM
+	help
+	  Say Y here if you want to build a platform specific variant MHU
+	  controller driver.
+	  The controller has a maximum of 3 mailbox channels, the last of
+	  which can be used in Secure mode only.
+
 config PL320_MBOX
 	bool "ARM PL320 Mailbox"
 	depends on ARM_AMBA

drivers/mailbox/Makefile

@@ -6,6 +6,8 @@ obj-$(CONFIG_MAILBOX_TEST)	+= mailbox-test.o
 
 obj-$(CONFIG_ARM_MHU)	+= arm_mhu.o
 
+obj-$(CONFIG_PLATFORM_MHU)	+= platform_mhu.o
+
 obj-$(CONFIG_PL320_MBOX)	+= pl320-ipc.o
 
 obj-$(CONFIG_OMAP2PLUS_MBOX)	+= omap-mailbox.o

drivers/mailbox/platform_mhu.c

@@ -0,0 +1,205 @@
+/*
+ * Copyright (C) 2016 BayLibre SAS.
+ * Author: Neil Armstrong <narmstrong@baylibre.com>
+ * Synchronised with arm_mhu.c from :
+ * 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/interrupt.h>
+#include <linux/spinlock.h>
+#include <linux/mutex.h>
+#include <linux/delay.h>
+#include <linux/slab.h>
+#include <linux/err.h>
+#include <linux/io.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/mailbox_controller.h>
+
+#define INTR_SET_OFS	0x0
+#define INTR_STAT_OFS	0x4
+#define INTR_CLR_OFS	0x8
+
+#define MHU_SEC_OFFSET	0x0
+#define MHU_LP_OFFSET	0xc
+#define MHU_HP_OFFSET	0x18
+#define TX_REG_OFFSET	0x24
+
+#define MHU_CHANS	3
+
+struct platform_mhu_link {
+	int irq;
+	void __iomem *tx_reg;
+	void __iomem *rx_reg;
+};
+
+struct platform_mhu {
+	void __iomem *base;
+	struct platform_mhu_link mlink[MHU_CHANS];
+	struct mbox_chan chan[MHU_CHANS];
+	struct mbox_controller mbox;
+};
+
+static irqreturn_t platform_mhu_rx_interrupt(int irq, void *p)
+{
+	struct mbox_chan *chan = p;
+	struct platform_mhu_link *mlink = chan->con_priv;
+	u32 val;
+
+	val = readl_relaxed(mlink->rx_reg + INTR_STAT_OFS);
+	if (!val)
+		return IRQ_NONE;
+
+	mbox_chan_received_data(chan, (void *)&val);
+
+	writel_relaxed(val, mlink->rx_reg + INTR_CLR_OFS);
+
+	return IRQ_HANDLED;
+}
+
+static bool platform_mhu_last_tx_done(struct mbox_chan *chan)
+{
+	struct platform_mhu_link *mlink = chan->con_priv;
+	u32 val = readl_relaxed(mlink->tx_reg + INTR_STAT_OFS);
+
+	return (val == 0);
+}
+
+static int platform_mhu_send_data(struct mbox_chan *chan, void *data)
+{
+	struct platform_mhu_link *mlink = chan->con_priv;
+	u32 *arg = data;
+
+	writel_relaxed(*arg, mlink->tx_reg + INTR_SET_OFS);
+
+	return 0;
+}
+
+static int platform_mhu_startup(struct mbox_chan *chan)
+{
+	struct platform_mhu_link *mlink = chan->con_priv;
+	u32 val;
+	int ret;
+
+	val = readl_relaxed(mlink->tx_reg + INTR_STAT_OFS);
+	writel_relaxed(val, mlink->tx_reg + INTR_CLR_OFS);
+
+	ret = request_irq(mlink->irq, platform_mhu_rx_interrupt,
+			  IRQF_SHARED, "platform_mhu_link", chan);
+	if (ret) {
+		dev_err(chan->mbox->dev,
+			"Unable to acquire IRQ %d\n", mlink->irq);
+		return ret;
+	}
+
+	return 0;
+}
+
+static void platform_mhu_shutdown(struct mbox_chan *chan)
+{
+	struct platform_mhu_link *mlink = chan->con_priv;
+
+	free_irq(mlink->irq, chan);
+}
+
+static const struct mbox_chan_ops platform_mhu_ops = {
+	.send_data = platform_mhu_send_data,
+	.startup = platform_mhu_startup,
+	.shutdown = platform_mhu_shutdown,
+	.last_tx_done = platform_mhu_last_tx_done,
+};
+
+static int platform_mhu_probe(struct platform_device *pdev)
+{
+	int i, err;
+	struct platform_mhu *mhu;
+	struct device *dev = &pdev->dev;
+	struct resource *res;
+	int platform_mhu_reg[MHU_CHANS] = {
+		MHU_SEC_OFFSET, MHU_LP_OFFSET, MHU_HP_OFFSET
+	};
+
+	/* Allocate memory for device */
+	mhu = devm_kzalloc(dev, sizeof(*mhu), GFP_KERNEL);
+	if (!mhu)
+		return -ENOMEM;
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	mhu->base = devm_ioremap_resource(dev, res);
+	if (IS_ERR(mhu->base)) {
+		dev_err(dev, "ioremap failed\n");
+		return PTR_ERR(mhu->base);
+	}
+
+	for (i = 0; i < MHU_CHANS; i++) {
+		mhu->chan[i].con_priv = &mhu->mlink[i];
+		mhu->mlink[i].irq = platform_get_irq(pdev, i);
+		if (mhu->mlink[i].irq < 0) {
+			dev_err(dev, "failed to get irq%d\n", i);
+			return mhu->mlink[i].irq;
+		}
+		mhu->mlink[i].rx_reg = mhu->base + platform_mhu_reg[i];
+		mhu->mlink[i].tx_reg = mhu->mlink[i].rx_reg + TX_REG_OFFSET;
+	}
+
+	mhu->mbox.dev = dev;
+	mhu->mbox.chans = &mhu->chan[0];
+	mhu->mbox.num_chans = MHU_CHANS;
+	mhu->mbox.ops = &platform_mhu_ops;
+	mhu->mbox.txdone_irq = false;
+	mhu->mbox.txdone_poll = true;
+	mhu->mbox.txpoll_period = 1;
+
+	platform_set_drvdata(pdev, mhu);
+
+	err = mbox_controller_register(&mhu->mbox);
+	if (err) {
+		dev_err(dev, "Failed to register mailboxes %d\n", err);
+		return err;
+	}
+
+	dev_info(dev, "Platform MHU Mailbox registered\n");
+	return 0;
+}
+
+static int platform_mhu_remove(struct platform_device *pdev)
+{
+	struct platform_mhu *mhu = platform_get_drvdata(pdev);
+
+	mbox_controller_unregister(&mhu->mbox);
+
+	return 0;
+}
+
+static const struct of_device_id platform_mhu_dt_ids[] = {
+	{ .compatible = "amlogic,meson-gxbb-mhu", },
+	{ /* sentinel */ },
+};
+MODULE_DEVICE_TABLE(of, platform_mhu_dt_ids);
+
+static struct platform_driver platform_mhu_driver = {
+	.probe	= platform_mhu_probe,
+	.remove	= platform_mhu_remove,
+	.driver = {
+		.name = "platform-mhu",
+		.of_match_table	= platform_mhu_dt_ids,
+	},
+};
+
+module_platform_driver(platform_mhu_driver);
+
+MODULE_LICENSE("GPL v2");
+MODULE_ALIAS("platform:platform-mhu");
+MODULE_DESCRIPTION("Platform MHU Driver");
+MODULE_AUTHOR("Neil Armstrong <narmstrong@baylibre.com>");