diff --git a/drivers/firmware/raspberrypi.c b/drivers/firmware/raspberrypi.c
new file mode 100644
index 0000000..a200a21
--- /dev/null
+++ b/drivers/firmware/raspberrypi.c
@@ -0,0 +1,285 @@
+/*
+ * Defines interfaces for interacting wtih the Raspberry Pi firmware's
+ * property channel.
+ *
+ * Copyright © 2015 Broadcom
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include <linux/dma-mapping.h>
+#include <linux/mailbox_client.h>
+#include <linux/module.h>
+#include <linux/of_platform.h>
+#include <linux/platform_device.h>
+#include <soc/bcm2835/raspberrypi-firmware.h>
+
+#define MBOX_MSG(chan, data28)		(((data28) & ~0xf) | ((chan) & 0xf))
+#define MBOX_CHAN(msg)			((msg) & 0xf)
+#define MBOX_DATA28(msg)		((msg) & ~0xf)
+#define MBOX_CHAN_PROPERTY		8
+
+#define MAX_RPI_FW_PROP_BUF_SIZE	32
+
+static struct platform_device *rpi_hwmon;
+
+struct rpi_firmware {
+	struct mbox_client cl;
+	struct mbox_chan *chan; /* The property channel. */
+	struct completion c;
+	u32 enabled;
+};
+
+static DEFINE_MUTEX(transaction_lock);
+
+static void response_callback(struct mbox_client *cl, void *msg)
+{
+	struct rpi_firmware *fw = container_of(cl, struct rpi_firmware, cl);
+	complete(&fw->c);
+}
+
+/*
+ * Sends a request to the firmware through the BCM2835 mailbox driver,
+ * and synchronously waits for the reply.
+ */
+static int
+rpi_firmware_transaction(struct rpi_firmware *fw, u32 chan, u32 data)
+{
+	u32 message = MBOX_MSG(chan, data);
+	int ret;
+
+	WARN_ON(data & 0xf);
+
+	mutex_lock(&transaction_lock);
+	reinit_completion(&fw->c);
+	ret = mbox_send_message(fw->chan, &message);
+	if (ret >= 0) {
+		wait_for_completion(&fw->c);
+		ret = 0;
+	} else {
+		dev_err(fw->cl.dev, "mbox_send_message returned %d\n", ret);
+	}
+	mutex_unlock(&transaction_lock);
+
+	return ret;
+}
+
+/**
+ * rpi_firmware_property_list - Submit firmware property list
+ * @fw:		Pointer to firmware structure from rpi_firmware_get().
+ * @data:	Buffer holding tags.
+ * @tag_size:	Size of tags buffer.
+ *
+ * Submits a set of concatenated tags to the VPU firmware through the
+ * mailbox property interface.
+ *
+ * The buffer header and the ending tag are added by this function and
+ * don't need to be supplied, just the actual tags for your operation.
+ * See struct rpi_firmware_property_tag_header for the per-tag
+ * structure.
+ */
+int rpi_firmware_property_list(struct rpi_firmware *fw,
+			       void *data, size_t tag_size)
+{
+	size_t size = tag_size + 12;
+	u32 *buf;
+	dma_addr_t bus_addr;
+	int ret;
+
+	/* Packets are processed a dword at a time. */
+	if (size & 3)
+		return -EINVAL;
+
+	buf = dma_alloc_coherent(fw->cl.dev, PAGE_ALIGN(size), &bus_addr,
+				 GFP_ATOMIC);
+	if (!buf)
+		return -ENOMEM;
+
+	/* The firmware will error out without parsing in this case. */
+	WARN_ON(size >= 1024 * 1024);
+
+	buf[0] = size;
+	buf[1] = RPI_FIRMWARE_STATUS_REQUEST;
+	memcpy(&buf[2], data, tag_size);
+	buf[size / 4 - 1] = RPI_FIRMWARE_PROPERTY_END;
+	wmb();
+
+	ret = rpi_firmware_transaction(fw, MBOX_CHAN_PROPERTY, bus_addr);
+
+	rmb();
+	memcpy(data, &buf[2], tag_size);
+	if (ret == 0 && buf[1] != RPI_FIRMWARE_STATUS_SUCCESS) {
+		/*
+		 * The tag name here might not be the one causing the
+		 * error, if there were multiple tags in the request.
+		 * But single-tag is the most common, so go with it.
+		 */
+		dev_err(fw->cl.dev, "Request 0x%08x returned status 0x%08x\n",
+			buf[2], buf[1]);
+		ret = -EINVAL;
+	}
+
+	dma_free_coherent(fw->cl.dev, PAGE_ALIGN(size), buf, bus_addr);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(rpi_firmware_property_list);
+
+/**
+ * rpi_firmware_property - Submit single firmware property
+ * @fw:		Pointer to firmware structure from rpi_firmware_get().
+ * @tag:	One of enum_mbox_property_tag.
+ * @tag_data:	Tag data buffer.
+ * @buf_size:	Buffer size.
+ *
+ * Submits a single tag to the VPU firmware through the mailbox
+ * property interface.
+ *
+ * This is a convenience wrapper around
+ * rpi_firmware_property_list() to avoid some of the
+ * boilerplate in property calls.
+ */
+int rpi_firmware_property(struct rpi_firmware *fw,
+			  u32 tag, void *tag_data, size_t buf_size)
+{
+	/* Single tags are very small (generally 8 bytes), so the
+	 * stack should be safe.
+	 */
+	u8 data[sizeof(struct rpi_firmware_property_tag_header) +
+		MAX_RPI_FW_PROP_BUF_SIZE];
+	struct rpi_firmware_property_tag_header *header =
+		(struct rpi_firmware_property_tag_header *)data;
+	int ret;
+
+	if (WARN_ON(buf_size > sizeof(data) - sizeof(*header)))
+		return -EINVAL;
+
+	header->tag = tag;
+	header->buf_size = buf_size;
+	header->req_resp_size = 0;
+	memcpy(data + sizeof(struct rpi_firmware_property_tag_header),
+	       tag_data, buf_size);
+
+	ret = rpi_firmware_property_list(fw, &data, buf_size + sizeof(*header));
+	memcpy(tag_data,
+	       data + sizeof(struct rpi_firmware_property_tag_header),
+	       buf_size);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(rpi_firmware_property);
+
+static void
+rpi_firmware_print_firmware_revision(struct rpi_firmware *fw)
+{
+	u32 packet;
+	int ret = rpi_firmware_property(fw,
+					RPI_FIRMWARE_GET_FIRMWARE_REVISION,
+					&packet, sizeof(packet));
+
+	if (ret == 0) {
+		struct tm tm;
+
+		time64_to_tm(packet, 0, &tm);
+
+		dev_info(fw->cl.dev,
+			 "Attached to firmware from %04ld-%02d-%02d %02d:%02d\n",
+			 tm.tm_year + 1900, tm.tm_mon + 1, tm.tm_mday,
+			 tm.tm_hour, tm.tm_min);
+	}
+}
+
+static void
+rpi_register_hwmon_driver(struct device *dev, struct rpi_firmware *fw)
+{
+	u32 packet;
+	int ret = rpi_firmware_property(fw, RPI_FIRMWARE_GET_THROTTLED,
+					&packet, sizeof(packet));
+
+	if (ret)
+		return;
+
+	rpi_hwmon = platform_device_register_data(dev, "raspberrypi-hwmon",
+						  -1, NULL, 0);
+}
+
+static int rpi_firmware_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct rpi_firmware *fw;
+
+	fw = devm_kzalloc(dev, sizeof(*fw), GFP_KERNEL);
+	if (!fw)
+		return -ENOMEM;
+
+	fw->cl.dev = dev;
+	fw->cl.rx_callback = response_callback;
+	fw->cl.tx_block = true;
+
+	fw->chan = mbox_request_channel(&fw->cl, 0);
+	if (IS_ERR(fw->chan)) {
+		int ret = PTR_ERR(fw->chan);
+		if (ret != -EPROBE_DEFER)
+			dev_err(dev, "Failed to get mbox channel: %d\n", ret);
+		return ret;
+	}
+
+	init_completion(&fw->c);
+
+	platform_set_drvdata(pdev, fw);
+
+	rpi_firmware_print_firmware_revision(fw);
+	rpi_register_hwmon_driver(dev, fw);
+
+	return 0;
+}
+
+static int rpi_firmware_remove(struct platform_device *pdev)
+{
+	struct rpi_firmware *fw = platform_get_drvdata(pdev);
+
+	platform_device_unregister(rpi_hwmon);
+	rpi_hwmon = NULL;
+	mbox_free_channel(fw->chan);
+
+	return 0;
+}
+
+/**
+ * rpi_firmware_get - Get pointer to rpi_firmware structure.
+ * @firmware_node:    Pointer to the firmware Device Tree node.
+ *
+ * Returns NULL is the firmware device is not ready.
+ */
+struct rpi_firmware *rpi_firmware_get(struct device_node *firmware_node)
+{
+	struct platform_device *pdev = of_find_device_by_node(firmware_node);
+
+	if (!pdev)
+		return NULL;
+
+	return platform_get_drvdata(pdev);
+}
+EXPORT_SYMBOL_GPL(rpi_firmware_get);
+
+static const struct of_device_id rpi_firmware_of_match[] = {
+	{ .compatible = "raspberrypi,bcm2835-firmware", },
+	{},
+};
+MODULE_DEVICE_TABLE(of, rpi_firmware_of_match);
+
+static struct platform_driver rpi_firmware_driver = {
+	.driver = {
+		.name = "raspberrypi-firmware",
+		.of_match_table = rpi_firmware_of_match,
+	},
+	.probe		= rpi_firmware_probe,
+	.remove		= rpi_firmware_remove,
+};
+module_platform_driver(rpi_firmware_driver);
+
+MODULE_AUTHOR("Eric Anholt <eric@anholt.net>");
+MODULE_DESCRIPTION("Raspberry Pi firmware driver");
+MODULE_LICENSE("GPL v2");