diff --git a/drivers/firmware/Kconfig b/drivers/firmware/Kconfig
index f754578414f0..7b665c52e6fd 100644
--- a/drivers/firmware/Kconfig
+++ b/drivers/firmware/Kconfig
@@ -267,6 +267,20 @@ config TI_SCI_PROTOCOL
 	  This protocol library is used by client drivers to use the features
 	  provided by the system controller.
 
+config TURRIS_MOX_RWTM
+	tristate "Turris Mox rWTM secure firmware driver"
+	depends on HAS_DMA && OF
+	depends on MAILBOX
+	select HW_RANDOM
+	select ARMADA_37XX_RWTM_MBOX
+	help
+	  This driver communicates with the firmware on the Cortex-M3 secure
+	  processor of the Turris Mox router. Enable if you are building for
+	  Turris Mox, and you will be able to read the serial number and
+	  other manufacturing data, sign messages with the internal ECDSA-521
+	  private key and utilize the Entropy Bit Generator as hardware random
+	  number generator.
+
 config HAVE_ARM_SMCCC
 	bool
 
diff --git a/drivers/firmware/Makefile b/drivers/firmware/Makefile
index 80feb635120f..7300787141f5 100644
--- a/drivers/firmware/Makefile
+++ b/drivers/firmware/Makefile
@@ -23,6 +23,7 @@ obj-$(CONFIG_QCOM_SCM_64)	+= qcom_scm-64.o
 obj-$(CONFIG_QCOM_SCM_32)	+= qcom_scm-32.o
 CFLAGS_qcom_scm-32.o :=$(call as-instr,.arch armv7-a\n.arch_extension sec,-DREQUIRES_SEC=1) -march=armv7-a
 obj-$(CONFIG_TI_SCI_PROTOCOL)	+= ti_sci.o
+obj-$(CONFIG_TURRIS_MOX_RWTM)	+= turris-mox-rwtm.o
 
 obj-$(CONFIG_ARM_SCMI_PROTOCOL)	+= arm_scmi/
 obj-y				+= broadcom/
diff --git a/drivers/firmware/turris-mox-rwtm.c b/drivers/firmware/turris-mox-rwtm.c
new file mode 100644
index 000000000000..e5d66460f85b
--- /dev/null
+++ b/drivers/firmware/turris-mox-rwtm.c
@@ -0,0 +1,508 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Turris Mox rWTM firmware driver
+ *
+ * Copyright (C) 2019 Marek Behun <marek.behun@nic.cz>
+ */
+
+#include <linux/armada-37xx-rwtm-mailbox.h>
+#include <linux/completion.h>
+#include <linux/dma-mapping.h>
+#include <linux/hw_random.h>
+#include <linux/mailbox_client.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/slab.h>
+
+#define DRIVER_NAME		"turris-mox-rwtm"
+
+/*
+ * The macros and constants below come from Turris Mox's rWTM firmware code.
+ * This firmware is open source and it's sources can be found at
+ * https://gitlab.labs.nic.cz/turris/mox-boot-builder/tree/master/wtmi.
+ */
+
+#define MBOX_STS_SUCCESS	(0 << 30)
+#define MBOX_STS_FAIL		(1 << 30)
+#define MBOX_STS_BADCMD		(2 << 30)
+#define MBOX_STS_ERROR(s)	((s) & (3 << 30))
+#define MBOX_STS_VALUE(s)	(((s) >> 10) & 0xfffff)
+#define MBOX_STS_CMD(s)		((s) & 0x3ff)
+
+enum mbox_cmd {
+	MBOX_CMD_GET_RANDOM	= 1,
+	MBOX_CMD_BOARD_INFO	= 2,
+	MBOX_CMD_ECDSA_PUB_KEY	= 3,
+	MBOX_CMD_HASH		= 4,
+	MBOX_CMD_SIGN		= 5,
+	MBOX_CMD_VERIFY		= 6,
+
+	MBOX_CMD_OTP_READ	= 7,
+	MBOX_CMD_OTP_WRITE	= 8,
+};
+
+struct mox_kobject;
+
+struct mox_rwtm {
+	struct device *dev;
+	struct mbox_client mbox_client;
+	struct mbox_chan *mbox;
+	struct mox_kobject *kobj;
+	struct hwrng hwrng;
+
+	struct armada_37xx_rwtm_rx_msg reply;
+
+	void *buf;
+	dma_addr_t buf_phys;
+
+	/*
+	 * If cmd_done_cb is not null, it is called on rWTM reply event.
+	 * Otherwise cmd_done completion is completed.
+	 */
+	struct mutex busy;
+	struct completion cmd_done;
+	void (*cmd_done_cb)(struct mox_rwtm *rwtm);
+
+	/* board information */
+	int has_board_info;
+	u64 serial_number;
+	int board_version, ram_size;
+	u8 mac_address1[6], mac_address2[6];
+
+	/* public key burned in eFuse */
+	int has_pubkey;
+	u8 pubkey[135];
+
+	/* signature process */
+	struct kernfs_node *do_sign_kn;
+	u32 last_sig[34];
+	int last_sig_result;
+};
+
+struct mox_kobject {
+	struct kobject kobj;
+	struct mox_rwtm *rwtm;
+};
+
+static inline struct kobject *rwtm_to_kobj(struct mox_rwtm *rwtm)
+{
+	return &rwtm->kobj->kobj;
+}
+
+static inline struct mox_rwtm *to_rwtm(struct kobject *kobj)
+{
+	return container_of(kobj, struct mox_kobject, kobj)->rwtm;
+}
+
+static void mox_kobj_release(struct kobject *kobj)
+{
+	kfree(to_rwtm(kobj)->kobj);
+}
+
+static struct kobj_type mox_kobj_ktype = {
+	.release	= mox_kobj_release,
+	.sysfs_ops	= &kobj_sysfs_ops,
+};
+
+static int mox_kobj_create(struct mox_rwtm *rwtm)
+{
+	rwtm->kobj = kzalloc(sizeof(*rwtm->kobj), GFP_KERNEL);
+	if (!rwtm->kobj)
+		return -ENOMEM;
+
+	kobject_init(rwtm_to_kobj(rwtm), &mox_kobj_ktype);
+	if (kobject_add(rwtm_to_kobj(rwtm), firmware_kobj, "turris-mox-rwtm")) {
+		kobject_put(rwtm_to_kobj(rwtm));
+		return -ENXIO;
+	}
+
+	rwtm->kobj->rwtm = rwtm;
+
+	return 0;
+}
+
+#define MOX_ATTR_RO(name, format, cat)				\
+static ssize_t							\
+name##_show(struct kobject *kobj, struct kobj_attribute *a,	\
+	    char *buf)						\
+{								\
+	struct mox_rwtm *rwtm = to_rwtm(kobj);	\
+	if (!rwtm->has_##cat)					\
+		return -ENODATA;				\
+	return sprintf(buf, format, rwtm->name);		\
+}								\
+static struct kobj_attribute mox_attr_##name = __ATTR_RO(name)
+
+MOX_ATTR_RO(serial_number, "%016llX\n", board_info);
+MOX_ATTR_RO(board_version, "%i\n", board_info);
+MOX_ATTR_RO(ram_size, "%i\n", board_info);
+MOX_ATTR_RO(mac_address1, "%pM\n", board_info);
+MOX_ATTR_RO(mac_address2, "%pM\n", board_info);
+MOX_ATTR_RO(pubkey, "%s\n", pubkey);
+
+static int mox_get_status(enum mbox_cmd cmd, u32 retval)
+{
+	if (MBOX_STS_CMD(retval) != cmd ||
+	    MBOX_STS_ERROR(retval) != MBOX_STS_SUCCESS)
+		return -EIO;
+	else if (MBOX_STS_ERROR(retval) == MBOX_STS_FAIL)
+		return -(int)MBOX_STS_VALUE(retval);
+	else
+		return MBOX_STS_VALUE(retval);
+}
+
+static ssize_t
+do_sign_show(struct kobject *kobj, struct kobj_attribute *a, char *buf)
+{
+	struct mox_rwtm *rwtm = to_rwtm(kobj);
+	int ret = rwtm->last_sig_result;
+
+	if (!ret)
+		return -ENODATA;
+
+	if (ret == 1) {
+		/* 2 arrays of 17 32-bit words are 136 bytes */
+		memcpy(buf, rwtm->last_sig, 136);
+		ret = 136;
+	}
+
+	rwtm->last_sig_result = 0;
+
+	return ret;
+}
+
+static void
+mox_signing_done(struct mox_rwtm *rwtm)
+{
+	struct armada_37xx_rwtm_rx_msg *reply = &rwtm->reply;
+	int ret;
+
+	ret = mox_get_status(MBOX_CMD_SIGN, reply->retval);
+	if (ret < 0) {
+		rwtm->last_sig_result = ret;
+	} else {
+		/*
+		 * Here we read the R and S values of the ECDSA signature
+		 * computed by the rWTM firmware and convert their words from
+		 * LE to BE.
+		 */
+		memcpy(rwtm->last_sig, rwtm->buf + 68, 136);
+		cpu_to_be32_array(rwtm->last_sig, rwtm->last_sig, 34);
+		rwtm->last_sig_result = 1;
+	}
+
+	rwtm->cmd_done_cb = NULL;
+	mutex_unlock(&rwtm->busy);
+
+	sysfs_notify_dirent(rwtm->do_sign_kn);
+}
+
+static ssize_t
+do_sign_store(struct kobject *kobj, struct kobj_attribute *a, const char *buf,
+	      size_t count)
+{
+	struct mox_rwtm *rwtm = to_rwtm(kobj);
+	struct armada_37xx_rwtm_tx_msg msg;
+	int ret;
+
+	/* the input is a SHA-512 hash, so exactly 64 bytes have to be read */
+	if (count != 64)
+		return -EINVAL;
+
+	/* if last result is not zero user has not read that information yet */
+	if (rwtm->last_sig_result)
+		return -EBUSY;
+
+	if (!mutex_trylock(&rwtm->busy))
+		return -EBUSY;
+
+	rwtm->cmd_done_cb = mox_signing_done;
+
+	/*
+	 * Here we have to send:
+	 *   1. Address of the input to sign.
+	 *      The input is an array of 17 32-bit words, the first (most
+	 *      significat) is 0, the rest 16 words are copied from the SHA-512
+	 *      hash given by the user and converted from BE to LE.
+	 *   2. Address of the buffer where ECDSA signature value R shall be
+	 *      stored by the rWTM firmware.
+	 *   3. Address of the buffer where ECDSA signature value S shall be
+	 *      stored by the rWTM firmware.
+	 */
+	memset(rwtm->buf, 0, 4);
+	memcpy(rwtm->buf + 4, buf, 64);
+	be32_to_cpu_array(rwtm->buf, rwtm->buf, 17);
+
+	msg.command = MBOX_CMD_SIGN;
+	msg.args[0] = 1;
+	msg.args[1] = rwtm->buf_phys;
+	msg.args[2] = rwtm->buf_phys + 68;
+	msg.args[3] = rwtm->buf_phys + 2 * 68;
+	ret = mbox_send_message(rwtm->mbox, &msg);
+	if (ret < 0)
+		goto unlock_mutex;
+
+	return count;
+unlock_mutex:
+	rwtm->cmd_done_cb = NULL;
+	mutex_unlock(&rwtm->busy);
+	return ret;
+}
+
+/* only root should be able to sign */
+static struct kobj_attribute mox_attr_do_sign =
+	__ATTR(do_sign, 0600, do_sign_show, do_sign_store);
+
+static const struct attribute *mox_rwtm_attrs[] = {
+	&mox_attr_serial_number.attr,
+	&mox_attr_board_version.attr,
+	&mox_attr_ram_size.attr,
+	&mox_attr_mac_address1.attr,
+	&mox_attr_mac_address2.attr,
+	&mox_attr_pubkey.attr,
+	&mox_attr_do_sign.attr,
+	NULL
+};
+
+static void mox_rwtm_rx_callback(struct mbox_client *cl, void *data)
+{
+	struct mox_rwtm *rwtm = dev_get_drvdata(cl->dev);
+	struct armada_37xx_rwtm_rx_msg *msg = data;
+
+	rwtm->reply = *msg;
+	if (rwtm->cmd_done_cb)
+		rwtm->cmd_done_cb(rwtm);
+	else
+		complete(&rwtm->cmd_done);
+}
+
+static void reply_to_mac_addr(u8 *mac, u32 t1, u32 t2)
+{
+	mac[0] = t1 >> 8;
+	mac[1] = t1;
+	mac[2] = t2 >> 24;
+	mac[3] = t2 >> 16;
+	mac[4] = t2 >> 8;
+	mac[5] = t2;
+}
+
+static int mox_get_board_info(struct mox_rwtm *rwtm)
+{
+	struct armada_37xx_rwtm_tx_msg msg;
+	struct armada_37xx_rwtm_rx_msg *reply = &rwtm->reply;
+	int ret;
+
+	msg.command = MBOX_CMD_BOARD_INFO;
+	ret = mbox_send_message(rwtm->mbox, &msg);
+	if (ret < 0)
+		return ret;
+
+	ret = wait_for_completion_timeout(&rwtm->cmd_done, HZ / 2);
+	if (ret < 0)
+		return ret;
+
+	ret = mox_get_status(MBOX_CMD_BOARD_INFO, reply->retval);
+	if (ret < 0 && ret != -ENODATA) {
+		return ret;
+	} else if (ret == -ENODATA) {
+		dev_warn(rwtm->dev,
+			 "Board does not have manufacturing information burned!\n");
+	} else {
+		rwtm->serial_number = reply->status[1];
+		rwtm->serial_number <<= 32;
+		rwtm->serial_number |= reply->status[0];
+			rwtm->board_version = reply->status[2];
+		rwtm->ram_size = reply->status[3];
+		reply_to_mac_addr(rwtm->mac_address1, reply->status[4],
+				  reply->status[5]);
+		reply_to_mac_addr(rwtm->mac_address2, reply->status[6],
+				  reply->status[7]);
+		rwtm->has_board_info = 1;
+
+		pr_info("Turris Mox serial number %016llX\n",
+			rwtm->serial_number);
+		pr_info("           board version %i\n", rwtm->board_version);
+		pr_info("           burned RAM size %i MiB\n", rwtm->ram_size);
+	}
+
+	msg.command = MBOX_CMD_ECDSA_PUB_KEY;
+	ret = mbox_send_message(rwtm->mbox, &msg);
+	if (ret < 0)
+		return ret;
+
+	ret = wait_for_completion_timeout(&rwtm->cmd_done, HZ / 2);
+	if (ret < 0)
+		return ret;
+
+	ret = mox_get_status(MBOX_CMD_ECDSA_PUB_KEY, reply->retval);
+	if (ret < 0 && ret != -ENODATA) {
+		return ret;
+	} else if (ret == -ENODATA) {
+		dev_warn(rwtm->dev, "Board has no public key burned!\n");
+	} else {
+		u32 *s = reply->status;
+
+		rwtm->has_pubkey = 1;
+		sprintf(rwtm->pubkey,
+			"%06x%08x%08x%08x%08x%08x%08x%08x%08x%08x%08x%08x%08x%08x%08x%08x%08x",
+			ret, s[0], s[1], s[2], s[3], s[4], s[5], s[6], s[7],
+			s[8], s[9], s[10], s[11], s[12], s[13], s[14], s[15]);
+	}
+
+	return 0;
+}
+
+static int mox_hwrng_read(struct hwrng *rng, void *data, size_t max, bool wait)
+{
+	struct mox_rwtm *rwtm = (struct mox_rwtm *) rng->priv;
+	struct armada_37xx_rwtm_tx_msg msg;
+	int ret;
+
+	if (max > 4096)
+		max = 4096;
+
+	msg.command = MBOX_CMD_GET_RANDOM;
+	msg.args[0] = 1;
+	msg.args[1] = rwtm->buf_phys;
+	msg.args[2] = (max + 3) & ~3;
+
+	if (!wait) {
+		if (!mutex_trylock(&rwtm->busy))
+			return -EBUSY;
+	} else {
+		mutex_lock(&rwtm->busy);
+	}
+
+	ret = mbox_send_message(rwtm->mbox, &msg);
+	if (ret < 0)
+		goto unlock_mutex;
+
+	ret = wait_for_completion_interruptible(&rwtm->cmd_done);
+	if (ret < 0)
+		goto unlock_mutex;
+
+	ret = mox_get_status(MBOX_CMD_GET_RANDOM, rwtm->reply.retval);
+	if (ret < 0)
+		goto unlock_mutex;
+
+	memcpy(data, rwtm->buf, max);
+	ret = max;
+
+unlock_mutex:
+	mutex_unlock(&rwtm->busy);
+	return ret;
+}
+
+static int turris_mox_rwtm_probe(struct platform_device *pdev)
+{
+	struct mox_rwtm *rwtm;
+	struct device *dev = &pdev->dev;
+	int ret;
+
+	rwtm = devm_kzalloc(dev, sizeof(*rwtm), GFP_KERNEL);
+	if (!rwtm)
+		return -ENOMEM;
+
+	rwtm->dev = dev;
+	rwtm->buf = dmam_alloc_coherent(dev, PAGE_SIZE, &rwtm->buf_phys,
+					GFP_KERNEL);
+	if (!rwtm->buf)
+		return -ENOMEM;
+
+	ret = mox_kobj_create(rwtm);
+	if (ret < 0) {
+		dev_err(dev, "Cannot create turris-mox-rwtm kobject!\n");
+		return ret;
+	}
+
+	ret = sysfs_create_files(rwtm_to_kobj(rwtm), mox_rwtm_attrs);
+	if (ret < 0) {
+		dev_err(dev, "Cannot create sysfs files!\n");
+		goto put_kobj;
+	}
+
+	rwtm->do_sign_kn = sysfs_get_dirent(rwtm->kobj->kobj.sd, "do_sign");
+	if (!rwtm->do_sign_kn) {
+		dev_err(dev, "Cannot get do_sign node\n");
+		ret = -ENXIO;
+		goto remove_files;
+	}
+
+	platform_set_drvdata(pdev, rwtm);
+
+	mutex_init(&rwtm->busy);
+
+	rwtm->mbox_client.dev = dev;
+	rwtm->mbox_client.rx_callback = mox_rwtm_rx_callback;
+
+	rwtm->mbox = mbox_request_channel(&rwtm->mbox_client, 0);
+	if (IS_ERR(rwtm->mbox)) {
+		ret = PTR_ERR(rwtm->mbox);
+		if (ret != -EPROBE_DEFER)
+			dev_err(dev, "Cannot request mailbox channel: %i\n",
+				ret);
+		goto remove_files;
+	}
+
+	init_completion(&rwtm->cmd_done);
+
+	ret = mox_get_board_info(rwtm);
+	if (ret < 0)
+		dev_warn(dev, "Cannot read board information: %i\n", ret);
+
+	rwtm->hwrng.name = DRIVER_NAME "_hwrng";
+	rwtm->hwrng.read = mox_hwrng_read;
+	rwtm->hwrng.priv = (unsigned long) rwtm;
+	rwtm->hwrng.quality = 1024;
+
+	ret = devm_hwrng_register(dev, &rwtm->hwrng);
+	if (ret < 0) {
+		dev_err(dev, "Cannot register HWRNG: %i\n", ret);
+		goto free_channel;
+	}
+
+	return 0;
+
+free_channel:
+	mbox_free_channel(rwtm->mbox);
+remove_files:
+	sysfs_remove_files(rwtm_to_kobj(rwtm), mox_rwtm_attrs);
+put_kobj:
+	kobject_put(rwtm_to_kobj(rwtm));
+	return ret;
+}
+
+static int turris_mox_rwtm_remove(struct platform_device *pdev)
+{
+	struct mox_rwtm *rwtm = platform_get_drvdata(pdev);
+
+	sysfs_put(rwtm->do_sign_kn);
+	sysfs_remove_files(rwtm_to_kobj(rwtm), mox_rwtm_attrs);
+	kobject_put(rwtm_to_kobj(rwtm));
+	mbox_free_channel(rwtm->mbox);
+
+	return 0;
+}
+
+static const struct of_device_id turris_mox_rwtm_match[] = {
+	{ .compatible = "cznic,turris-mox-rwtm", },
+	{ },
+};
+
+MODULE_DEVICE_TABLE(of, turris_mox_rwtm_match);
+
+static struct platform_driver turris_mox_rwtm_driver = {
+	.probe	= turris_mox_rwtm_probe,
+	.remove	= turris_mox_rwtm_remove,
+	.driver	= {
+		.name		= DRIVER_NAME,
+		.of_match_table	= turris_mox_rwtm_match,
+	},
+};
+module_platform_driver(turris_mox_rwtm_driver);
+
+MODULE_LICENSE("GPL v2");
+MODULE_DESCRIPTION("Turris Mox rWTM firmware driver");
+MODULE_AUTHOR("Marek Behun <marek.behun@nic.cz>");
