diff --git a/drivers/mailbox/Kconfig b/drivers/mailbox/Kconfig
index 3eeb12e93e98..939927290ac6 100644
--- a/drivers/mailbox/Kconfig
+++ b/drivers/mailbox/Kconfig
@@ -41,6 +41,16 @@ config PL320_MBOX
 	  Management Engine, primarily for cpufreq. Say Y here if you want
 	  to use the PL320 IPCM support.
 
+config ARMADA_37XX_RWTM_MBOX
+	tristate "Armada 37xx rWTM BIU Mailbox"
+	depends on ARCH_MVEBU || COMPILE_TEST
+	depends on OF
+	help
+	  Mailbox implementation for communication with the the firmware
+	  running on the Cortex-M3 rWTM secure processor of the Armada 37xx
+	  SOC. Say Y here if you are building for such a device (for example
+	  the Turris Mox router).
+
 config OMAP2PLUS_MBOX
 	tristate "OMAP2+ Mailbox framework support"
 	depends on ARCH_OMAP2PLUS
diff --git a/drivers/mailbox/Makefile b/drivers/mailbox/Makefile
index c818b5d011ae..792894db6b43 100644
--- a/drivers/mailbox/Makefile
+++ b/drivers/mailbox/Makefile
@@ -9,6 +9,8 @@ obj-$(CONFIG_ARM_MHU)	+= arm_mhu.o
 
 obj-$(CONFIG_IMX_MBOX)	+= imx-mailbox.o
 
+obj-$(CONFIG_ARMADA_37XX_RWTM_MBOX)	+= armada-37xx-rwtm-mailbox.o
+
 obj-$(CONFIG_PLATFORM_MHU)	+= platform_mhu.o
 
 obj-$(CONFIG_PL320_MBOX)	+= pl320-ipc.o
diff --git a/drivers/mailbox/armada-37xx-rwtm-mailbox.c b/drivers/mailbox/armada-37xx-rwtm-mailbox.c
new file mode 100644
index 000000000000..97f90e97a83c
--- /dev/null
+++ b/drivers/mailbox/armada-37xx-rwtm-mailbox.c
@@ -0,0 +1,225 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * rWTM BIU Mailbox driver for Armada 37xx
+ *
+ * Author: Marek Behun <marek.behun@nic.cz>
+ */
+
+#include <linux/device.h>
+#include <linux/interrupt.h>
+#include <linux/io.h>
+#include <linux/kernel.h>
+#include <linux/mailbox_controller.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/armada-37xx-rwtm-mailbox.h>
+
+#define DRIVER_NAME	"armada-37xx-rwtm-mailbox"
+
+/* relative to rWTM BIU Mailbox Registers */
+#define RWTM_MBOX_PARAM(i)		(0x0 + ((i) << 2))
+#define RWTM_MBOX_COMMAND		0x40
+#define RWTM_MBOX_RETURN_STATUS		0x80
+#define RWTM_MBOX_STATUS(i)		(0x84 + ((i) << 2))
+#define RWTM_MBOX_FIFO_STATUS		0xc4
+#define FIFO_STS_RDY			0x100
+#define FIFO_STS_CNTR_MASK		0x7
+#define FIFO_STS_CNTR_MAX		4
+
+#define RWTM_HOST_INT_RESET		0xc8
+#define RWTM_HOST_INT_MASK		0xcc
+#define SP_CMD_COMPLETE			BIT(0)
+#define SP_CMD_QUEUE_FULL_ACCESS	BIT(17)
+#define SP_CMD_QUEUE_FULL		BIT(18)
+
+struct a37xx_mbox {
+	struct device *dev;
+	struct mbox_controller controller;
+	void __iomem *base;
+	int irq;
+};
+
+static void a37xx_mbox_receive(struct mbox_chan *chan)
+{
+	struct a37xx_mbox *mbox = chan->con_priv;
+	struct armada_37xx_rwtm_rx_msg rx_msg;
+	int i;
+
+	rx_msg.retval = readl(mbox->base + RWTM_MBOX_RETURN_STATUS);
+	for (i = 0; i < 16; ++i)
+		rx_msg.status[i] = readl(mbox->base + RWTM_MBOX_STATUS(i));
+
+	mbox_chan_received_data(chan, &rx_msg);
+}
+
+static irqreturn_t a37xx_mbox_irq_handler(int irq, void *data)
+{
+	struct mbox_chan *chan = data;
+	struct a37xx_mbox *mbox = chan->con_priv;
+	u32 reg;
+
+	reg = readl(mbox->base + RWTM_HOST_INT_RESET);
+
+	if (reg & SP_CMD_COMPLETE)
+		a37xx_mbox_receive(chan);
+
+	if (reg & (SP_CMD_QUEUE_FULL_ACCESS | SP_CMD_QUEUE_FULL))
+		dev_err(mbox->dev, "Secure processor command queue full\n");
+
+	writel(reg, mbox->base + RWTM_HOST_INT_RESET);
+	if (reg)
+		mbox_chan_txdone(chan, 0);
+
+	return reg ? IRQ_HANDLED : IRQ_NONE;
+}
+
+static int a37xx_mbox_send_data(struct mbox_chan *chan, void *data)
+{
+	struct a37xx_mbox *mbox = chan->con_priv;
+	struct armada_37xx_rwtm_tx_msg *msg = data;
+	int i;
+	u32 reg;
+
+	if (!data)
+		return -EINVAL;
+
+	reg = readl(mbox->base + RWTM_MBOX_FIFO_STATUS);
+	if (!(reg & FIFO_STS_RDY))
+		dev_warn(mbox->dev, "Secure processor not ready\n");
+
+	if ((reg & FIFO_STS_CNTR_MASK) >= FIFO_STS_CNTR_MAX) {
+		dev_err(mbox->dev, "Secure processor command queue full\n");
+		return -EBUSY;
+	}
+
+	for (i = 0; i < 16; ++i)
+		writel(msg->args[i], mbox->base + RWTM_MBOX_PARAM(i));
+	writel(msg->command, mbox->base + RWTM_MBOX_COMMAND);
+
+	return 0;
+}
+
+static int a37xx_mbox_startup(struct mbox_chan *chan)
+{
+	struct a37xx_mbox *mbox = chan->con_priv;
+	u32 reg;
+	int ret;
+
+	ret = devm_request_irq(mbox->dev, mbox->irq, a37xx_mbox_irq_handler, 0,
+			       DRIVER_NAME, chan);
+	if (ret < 0) {
+		dev_err(mbox->dev, "Cannot request irq\n");
+		return ret;
+	}
+
+	/* enable IRQ generation */
+	reg = readl(mbox->base + RWTM_HOST_INT_MASK);
+	reg &= ~(SP_CMD_COMPLETE | SP_CMD_QUEUE_FULL_ACCESS | SP_CMD_QUEUE_FULL);
+	writel(reg, mbox->base + RWTM_HOST_INT_MASK);
+
+	return 0;
+}
+
+static void a37xx_mbox_shutdown(struct mbox_chan *chan)
+{
+	u32 reg;
+	struct a37xx_mbox *mbox = chan->con_priv;
+
+	/* disable interrupt generation */
+	reg = readl(mbox->base + RWTM_HOST_INT_MASK);
+	reg |= SP_CMD_COMPLETE | SP_CMD_QUEUE_FULL_ACCESS | SP_CMD_QUEUE_FULL;
+	writel(reg, mbox->base + RWTM_HOST_INT_MASK);
+
+	devm_free_irq(mbox->dev, mbox->irq, chan);
+}
+
+static const struct mbox_chan_ops a37xx_mbox_ops = {
+	.send_data	= a37xx_mbox_send_data,
+	.startup	= a37xx_mbox_startup,
+	.shutdown	= a37xx_mbox_shutdown,
+};
+
+static int armada_37xx_mbox_probe(struct platform_device *pdev)
+{
+	struct a37xx_mbox *mbox;
+	struct resource *regs;
+	struct mbox_chan *chans;
+	int ret;
+
+	mbox = devm_kzalloc(&pdev->dev, sizeof(*mbox), GFP_KERNEL);
+	if (!mbox)
+		return -ENOMEM;
+
+	/* Allocated one channel */
+	chans = devm_kzalloc(&pdev->dev, sizeof(*chans), GFP_KERNEL);
+	if (!chans)
+		return -ENOMEM;
+
+	regs = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+
+	mbox->base = devm_ioremap_resource(&pdev->dev, regs);
+	if (IS_ERR(mbox->base)) {
+		dev_err(&pdev->dev, "ioremap failed\n");
+		return PTR_ERR(mbox->base);
+	}
+
+	mbox->irq = platform_get_irq(pdev, 0);
+	if (mbox->irq < 0) {
+		dev_err(&pdev->dev, "Cannot get irq\n");
+		return mbox->irq;
+	}
+
+	mbox->dev = &pdev->dev;
+
+	/* Hardware supports only one channel. */
+	chans[0].con_priv = mbox;
+	mbox->controller.dev = mbox->dev;
+	mbox->controller.num_chans = 1;
+	mbox->controller.chans = chans;
+	mbox->controller.ops = &a37xx_mbox_ops;
+	mbox->controller.txdone_irq = true;
+
+	ret = mbox_controller_register(&mbox->controller);
+	if (ret) {
+		dev_err(&pdev->dev, "Could not register mailbox controller\n");
+		return ret;
+	}
+
+	platform_set_drvdata(pdev, mbox);
+	return ret;
+}
+
+static int armada_37xx_mbox_remove(struct platform_device *pdev)
+{
+	struct a37xx_mbox *mbox = platform_get_drvdata(pdev);
+
+	if (!mbox)
+		return -EINVAL;
+
+	mbox_controller_unregister(&mbox->controller);
+
+	return 0;
+}
+
+static const struct of_device_id armada_37xx_mbox_match[] = {
+	{ .compatible = "marvell,armada-3700-rwtm-mailbox" },
+	{ },
+};
+
+MODULE_DEVICE_TABLE(of, armada_37xx_mbox_match);
+
+static struct platform_driver armada_37xx_mbox_driver = {
+	.probe	= armada_37xx_mbox_probe,
+	.remove	= armada_37xx_mbox_remove,
+	.driver	= {
+		.name		= DRIVER_NAME,
+		.of_match_table	= armada_37xx_mbox_match,
+	},
+};
+
+module_platform_driver(armada_37xx_mbox_driver);
+
+MODULE_LICENSE("GPL v2");
+MODULE_DESCRIPTION("rWTM BIU Mailbox driver for Armada 37xx");
+MODULE_AUTHOR("Marek Behun <marek.behun@nic.cz>");
diff --git a/include/linux/armada-37xx-rwtm-mailbox.h b/include/linux/armada-37xx-rwtm-mailbox.h
new file mode 100644
index 000000000000..57bb54f6767a
--- /dev/null
+++ b/include/linux/armada-37xx-rwtm-mailbox.h
@@ -0,0 +1,23 @@
+/* SPDX-License-Identifier: GPL-2.0+ */
+/*
+ * rWTM BIU Mailbox driver for Armada 37xx
+ *
+ * Author: Marek Behun <marek.behun@nic.cz>
+ */
+
+#ifndef _LINUX_ARMADA_37XX_RWTM_MAILBOX_H_
+#define _LINUX_ARMADA_37XX_RWTM_MAILBOX_H_
+
+#include <linux/types.h>
+
+struct armada_37xx_rwtm_tx_msg {
+	u16 command;
+	u32 args[16];
+};
+
+struct armada_37xx_rwtm_rx_msg {
+	u32 retval;
+	u32 status[16];
+};
+
+#endif /* _LINUX_ARMADA_37XX_RWTM_MAILBOX_H_ */
