diff --git a/doc/README.i2c b/doc/README.i2c
new file mode 100644
index 0000000..07cd8df
--- /dev/null
+++ b/doc/README.i2c
@@ -0,0 +1,60 @@
+I2C Bus Arbitration
+===================
+
+While I2C supports multi-master buses this is difficult to get right.
+The implementation on the master side in software is quite complex.
+Clock-stretching and the arbitrary time that an I2C transaction can take
+make it difficult to share the bus fairly in the face of high traffic.
+When one or more masters can be reset independently part-way through a
+transaction it is hard to know the state of the bus.
+
+U-Boot provides a scheme based on two 'claim' GPIOs, one driven by the
+AP (Application Processor, meaning the main CPU) and one driven by the EC
+(Embedded Controller, a small CPU aimed at handling system tasks). With
+these they can communicate and reliably share the bus. This scheme has
+minimal overhead and involves very little code. The scheme can survive
+reboots by either side without difficulty.
+
+Since U-Boot runs on the AP, the terminology used is 'our' claim GPIO,
+meaning the AP's, and 'their' claim GPIO, meaning the EC's. This terminology
+is used by the device tree bindings in Linux also.
+
+The driver is implemented as an I2C mux, as it is in Linux. See
+i2c-arb-gpio-challenge for the implementation.
+
+GPIO lines are shared between the AP and EC to manage the bus. The AP and EC
+each have a 'bus claim' line, which is an output that the other can see.
+
+- AP_CLAIM: output from AP, signalling to the EC that the AP wants the bus
+- EC_CLAIM: output from EC, signalling to the AP that the EC wants the bus
+
+The basic algorithm is to assert your line when you want the bus, then make
+sure that the other side doesn't want it also. A detailed explanation is best
+done with an example.
+
+Let's say the AP wants to claim the bus. It:
+
+1. Asserts AP_CLAIM
+2. Waits a little bit for the other side to notice (slew time)
+3. Checks EC_CLAIM. If this is not asserted, then the AP has the bus, and we
+   are done
+4. Otherwise, wait for a few milliseconds (retry time) and see if EC_CLAIM is
+   released
+5. If not, back off, release the claim and wait for a few more milliseconds
+  (retry time again)
+6. Go back to 1 if things don't look wedged (wait time has expired)
+7. Panic. The other side is hung with the CLAIM line set.
+
+The same algorithm applies on the EC.
+
+To release the bus, just de-assert the claim line.
+
+Typical delays are:
+- slew time 10 us
+- retry time 3 ms
+- wait time - 50ms
+
+In general the traffic is fairly light, and in particular the EC wants access
+to the bus quite rarely (maybe every 10s or 30s to check the battery). This
+scheme works very nicely with very low contention. There is only a 10 us
+wait for access to the bus assuming that the other side isn't using it.
diff --git a/drivers/i2c/muxes/Kconfig b/drivers/i2c/muxes/Kconfig
index a05b32d..bd3e078 100644
--- a/drivers/i2c/muxes/Kconfig
+++ b/drivers/i2c/muxes/Kconfig
@@ -6,3 +6,12 @@ config I2C_MUX
 	  one of several buses using some sort of control mechanism. The
 	  bus select is handled automatically when that bus is accessed,
 	  using a suitable I2C MUX driver.
+
+config I2C_ARB_GPIO_CHALLENGE
+        bool "GPIO-based I2C arbitration"
+        depends on I2C_MUX
+        help
+          If you say yes to this option, support will be included for an
+          I2C multimaster arbitration scheme using GPIOs and a challenge &
+          response mechanism where masters have to claim the bus by asserting
+          a GPIO.
diff --git a/drivers/i2c/muxes/Makefile b/drivers/i2c/muxes/Makefile
index 7583e3a..612cc27 100644
--- a/drivers/i2c/muxes/Makefile
+++ b/drivers/i2c/muxes/Makefile
@@ -3,4 +3,5 @@
 #
 # SPDX-License-Identifier:	GPL-2.0+
 #
+obj-$(CONFIG_I2C_ARB_GPIO_CHALLENGE) += i2c-arb-gpio-challenge.o
 obj-$(CONFIG_I2C_MUX) += i2c-mux-uclass.o
diff --git a/drivers/i2c/muxes/i2c-arb-gpio-challenge.c b/drivers/i2c/muxes/i2c-arb-gpio-challenge.c
new file mode 100644
index 0000000..3f072c7
--- /dev/null
+++ b/drivers/i2c/muxes/i2c-arb-gpio-challenge.c
@@ -0,0 +1,147 @@
+/*
+ * Copyright (c) 2015 Google, Inc
+ * Written by Simon Glass <sjg@chromium.org>
+ *
+ * SPDX-License-Identifier:	GPL-2.0+
+ */
+
+#include <common.h>
+#include <dm.h>
+#include <errno.h>
+#include <i2c.h>
+#include <asm/gpio.h>
+
+DECLARE_GLOBAL_DATA_PTR;
+
+struct i2c_arbitrator_priv {
+	struct gpio_desc ap_claim;
+	struct gpio_desc ec_claim;
+	uint slew_delay_us;
+	uint wait_retry_ms;
+	uint wait_free_ms;
+};
+
+int i2c_arbitrator_deselect(struct udevice *mux, struct udevice *bus,
+			    uint channel)
+{
+	struct i2c_arbitrator_priv *priv = dev_get_priv(mux);
+	int ret;
+
+	debug("%s: %s\n", __func__, mux->name);
+	ret = dm_gpio_set_value(&priv->ap_claim, 0);
+	udelay(priv->slew_delay_us);
+
+	return ret;
+}
+
+int i2c_arbitrator_select(struct udevice *mux, struct udevice *bus,
+			  uint channel)
+{
+	struct i2c_arbitrator_priv *priv = dev_get_priv(mux);
+	unsigned start;
+	int ret;
+
+	debug("%s: %s\n", __func__, mux->name);
+	/* Start a round of trying to claim the bus */
+	start = get_timer(0);
+	do {
+		unsigned start_retry;
+		int waiting = 0;
+
+		/* Indicate that we want to claim the bus */
+		ret = dm_gpio_set_value(&priv->ap_claim, 1);
+		if (ret)
+			goto err;
+		udelay(priv->slew_delay_us);
+
+		/* Wait for the EC to release it */
+		start_retry = get_timer(0);
+		while (get_timer(start_retry) < priv->wait_retry_ms) {
+			ret = dm_gpio_get_value(&priv->ec_claim);
+			if (ret < 0) {
+				goto err;
+			} else if (!ret) {
+				/* We got it, so return */
+				return 0;
+			}
+
+			if (!waiting)
+				waiting = 1;
+		}
+
+		/* It didn't release, so give up, wait, and try again */
+		ret = dm_gpio_set_value(&priv->ap_claim, 0);
+		if (ret)
+			goto err;
+
+		mdelay(priv->wait_retry_ms);
+	} while (get_timer(start) < priv->wait_free_ms);
+
+	/* Give up, release our claim */
+	printf("I2C: Could not claim bus, timeout %lu\n", get_timer(start));
+	ret = -ETIMEDOUT;
+	ret = 0;
+err:
+	return ret;
+}
+
+static int i2c_arbitrator_probe(struct udevice *dev)
+{
+	struct i2c_arbitrator_priv *priv = dev_get_priv(dev);
+	const void *blob = gd->fdt_blob;
+	int node = dev->of_offset;
+	int ret;
+
+	debug("%s: %s\n", __func__, dev->name);
+	priv->slew_delay_us = fdtdec_get_int(blob, node, "slew-delay-us", 0);
+	priv->wait_retry_ms = fdtdec_get_int(blob, node, "wait-retry-us", 0) /
+		1000;
+	priv->wait_free_ms = fdtdec_get_int(blob, node, "wait-free-us", 0) /
+		1000;
+	ret = gpio_request_by_name(dev, "our-claim-gpio", 0, &priv->ap_claim,
+				   GPIOD_IS_OUT);
+	if (ret)
+		goto err;
+	ret = gpio_request_by_name(dev, "their-claim-gpios", 0, &priv->ec_claim,
+				   GPIOD_IS_IN);
+	if (ret)
+		goto err_ec_gpio;
+
+	return 0;
+
+err_ec_gpio:
+	dm_gpio_free(dev, &priv->ap_claim);
+err:
+	debug("%s: ret=%d\n", __func__, ret);
+	return ret;
+}
+
+static int i2c_arbitrator_remove(struct udevice *dev)
+{
+	struct i2c_arbitrator_priv *priv = dev_get_priv(dev);
+
+	dm_gpio_free(dev, &priv->ap_claim);
+	dm_gpio_free(dev, &priv->ec_claim);
+
+	return 0;
+}
+
+static const struct i2c_mux_ops i2c_arbitrator_ops = {
+	.select		= i2c_arbitrator_select,
+	.deselect	= i2c_arbitrator_deselect,
+};
+
+static const struct udevice_id i2c_arbitrator_ids[] = {
+	{ .compatible = "i2c-arb-gpio-challenge" },
+	{ }
+};
+
+U_BOOT_DRIVER(i2c_arbitrator) = {
+	.name = "i2c_arbitrator",
+	.id = UCLASS_I2C_MUX,
+	.of_match = i2c_arbitrator_ids,
+	.probe = i2c_arbitrator_probe,
+	.remove = i2c_arbitrator_remove,
+	.ops = &i2c_arbitrator_ops,
+	.priv_auto_alloc_size = sizeof(struct i2c_arbitrator_priv),
+};