From 5353fc464f00b2bf8e69ddbbcb4f1704566bcde2 Mon Sep 17 00:00:00 2001
From: Tuyen Dang <tuyen.dang.xa@renesas.com>
Date: Mon, 27 Oct 2025 17:39:17 +0100
Subject: [PATCH] mailbox: renesas: Add Renesas MFIS Multifunctional Interface
 mailbox driver

Add support for the Renesas MFIS mailbox, which provides an interface
between the different CPU Cores, such as AP System Core domain and the
Realtime Core domain, SCP Core domain and AP System Core domain or
Realtime Core domain and AP System Core domain or Realtime Core domain.

Signed-off-by: Tuyen Dang <tuyen.dang.xa@renesas.com>
Signed-off-by: Marek Vasut <marek.vasut+renesas@mailbox.org> # Update the driver
[Marek: Rename the driver to renesas-mfis, simplify the driver.
        Always use only one TX channel and no RX channel, drop all
	unnecessary code. Perform 1ms delay in send callback which
	is perfectly fine to do in U-Boot which does RX polling]
---
 drivers/mailbox/Kconfig        | 10 ++++++
 drivers/mailbox/Makefile       |  1 +
 drivers/mailbox/renesas-mfis.c | 59 ++++++++++++++++++++++++++++++++++
 3 files changed, 70 insertions(+)
 create mode 100644 drivers/mailbox/renesas-mfis.c

diff --git a/drivers/mailbox/Kconfig b/drivers/mailbox/Kconfig
index f9531c1627c..cfd2a3be3fd 100644
--- a/drivers/mailbox/Kconfig
+++ b/drivers/mailbox/Kconfig
@@ -66,6 +66,16 @@ config K3_SEC_PROXY
 	  Select this driver if your platform has support for this hardware
 	  block.
 
+config RCAR_MFIS_MBOX
+	bool "Renesas MFIS Multifunctional Interface mailbox driver"
+	depends on DM_MAILBOX && ARCH_RENESAS
+	help
+	  This enables support for the Renesas MFIS mailbox module, which
+	  provides an interface between the different CPU Cores, such as AP
+	  System Core domain and the Realtime Core domain, SCP Core domain
+	  and AP System Core domain or Realtime Core domain and AP System
+	  Core domain or Realtime Core domain.
+
 config ZYNQMP_IPI
 	bool "Xilinx ZynqMP IPI controller support"
 	depends on DM_MAILBOX && (ARCH_ZYNQMP || ARCH_VERSAL || ARCH_VERSAL_NET || ARCH_VERSAL2)
diff --git a/drivers/mailbox/Makefile b/drivers/mailbox/Makefile
index b54fbdfff15..b3a36691497 100644
--- a/drivers/mailbox/Makefile
+++ b/drivers/mailbox/Makefile
@@ -12,4 +12,5 @@ obj-$(CONFIG_SANDBOX_MBOX) += sandbox-mbox-test.o
 obj-$(CONFIG_STM32_IPCC) += stm32-ipcc.o
 obj-$(CONFIG_TEGRA_HSP) += tegra-hsp.o
 obj-$(CONFIG_K3_SEC_PROXY) += k3-sec-proxy.o
+obj-$(CONFIG_RCAR_MFIS_MBOX) += renesas-mfis.o
 obj-$(CONFIG_ZYNQMP_IPI) += zynqmp-ipi.o
diff --git a/drivers/mailbox/renesas-mfis.c b/drivers/mailbox/renesas-mfis.c
new file mode 100644
index 00000000000..1e9e8285974
--- /dev/null
+++ b/drivers/mailbox/renesas-mfis.c
@@ -0,0 +1,59 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (c) 2020-2025, Renesas Electronics Corporation.
+ */
+
+#include <asm/io.h>
+#include <dm.h>
+#include <linux/delay.h>
+#include <mailbox-uclass.h>
+
+#define COM		0x0
+#define IIR		BIT(0)
+
+struct mfis_priv {
+	void __iomem	*tx_base;
+};
+
+static int mfis_send(struct mbox_chan *chan, const void *data)
+{
+	struct mfis_priv *mfis = dev_get_priv(chan->dev);
+
+	writel(IIR, mfis->tx_base + COM);
+
+	/* Give the remote side some time. */
+	mdelay(1);
+
+	writel(0, mfis->tx_base + COM);
+
+	return 0;
+}
+
+struct mbox_ops mfis_mbox_ops = {
+	.send		= mfis_send,
+};
+
+static int mfis_mbox_probe(struct udevice *dev)
+{
+	struct mfis_priv *mbox = dev_get_priv(dev);
+
+	mbox->tx_base = dev_read_addr_index_ptr(dev, 0);
+	if (!mbox->tx_base)
+		return -ENODEV;
+
+	return 0;
+}
+
+static const struct udevice_id mfis_mbox_of_match[] = {
+	{ .compatible = "renesas,mfis-mbox", },
+	{},
+};
+
+U_BOOT_DRIVER(renesas_mfis) = {
+	.name		= "renesas-mfis",
+	.id		= UCLASS_MAILBOX,
+	.of_match	= mfis_mbox_of_match,
+	.probe		= mfis_mbox_probe,
+	.priv_auto	= sizeof(struct mfis_priv),
+	.ops		= &mfis_mbox_ops,
+};
-- 
2.47.3