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@@ -0,0 +1,147 @@
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+/*
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+ * Copyright (c) 2015 Google, Inc
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+ * Written by Simon Glass <sjg@chromium.org>
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+ *
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+ * SPDX-License-Identifier: GPL-2.0+
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+ */
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+
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+#include <common.h>
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+#include <dm.h>
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+#include <errno.h>
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+#include <i2c.h>
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+#include <asm/gpio.h>
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+
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+DECLARE_GLOBAL_DATA_PTR;
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+
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+struct i2c_arbitrator_priv {
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+ struct gpio_desc ap_claim;
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+ struct gpio_desc ec_claim;
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+ uint slew_delay_us;
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+ uint wait_retry_ms;
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+ uint wait_free_ms;
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+};
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+
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+int i2c_arbitrator_deselect(struct udevice *mux, struct udevice *bus,
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+ uint channel)
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+{
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+ struct i2c_arbitrator_priv *priv = dev_get_priv(mux);
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+ int ret;
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+
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+ debug("%s: %s\n", __func__, mux->name);
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+ ret = dm_gpio_set_value(&priv->ap_claim, 0);
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+ udelay(priv->slew_delay_us);
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+
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+ return ret;
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+}
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+
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+int i2c_arbitrator_select(struct udevice *mux, struct udevice *bus,
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+ uint channel)
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+{
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+ struct i2c_arbitrator_priv *priv = dev_get_priv(mux);
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+ unsigned start;
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+ int ret;
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+
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+ debug("%s: %s\n", __func__, mux->name);
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+ /* Start a round of trying to claim the bus */
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+ start = get_timer(0);
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+ do {
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+ unsigned start_retry;
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+ int waiting = 0;
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+
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+ /* Indicate that we want to claim the bus */
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+ ret = dm_gpio_set_value(&priv->ap_claim, 1);
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+ if (ret)
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+ goto err;
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+ udelay(priv->slew_delay_us);
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+
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+ /* Wait for the EC to release it */
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+ start_retry = get_timer(0);
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+ while (get_timer(start_retry) < priv->wait_retry_ms) {
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+ ret = dm_gpio_get_value(&priv->ec_claim);
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+ if (ret < 0) {
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+ goto err;
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+ } else if (!ret) {
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+ /* We got it, so return */
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+ return 0;
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+ }
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+
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+ if (!waiting)
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+ waiting = 1;
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+ }
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+
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+ /* It didn't release, so give up, wait, and try again */
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+ ret = dm_gpio_set_value(&priv->ap_claim, 0);
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+ if (ret)
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+ goto err;
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+
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+ mdelay(priv->wait_retry_ms);
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+ } while (get_timer(start) < priv->wait_free_ms);
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+
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+ /* Give up, release our claim */
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+ printf("I2C: Could not claim bus, timeout %lu\n", get_timer(start));
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+ ret = -ETIMEDOUT;
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+ ret = 0;
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+err:
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+ return ret;
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+}
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+
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+static int i2c_arbitrator_probe(struct udevice *dev)
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+{
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+ struct i2c_arbitrator_priv *priv = dev_get_priv(dev);
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+ const void *blob = gd->fdt_blob;
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+ int node = dev->of_offset;
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+ int ret;
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+
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+ debug("%s: %s\n", __func__, dev->name);
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+ priv->slew_delay_us = fdtdec_get_int(blob, node, "slew-delay-us", 0);
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+ priv->wait_retry_ms = fdtdec_get_int(blob, node, "wait-retry-us", 0) /
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+ 1000;
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+ priv->wait_free_ms = fdtdec_get_int(blob, node, "wait-free-us", 0) /
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+ 1000;
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+ ret = gpio_request_by_name(dev, "our-claim-gpio", 0, &priv->ap_claim,
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+ GPIOD_IS_OUT);
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+ if (ret)
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+ goto err;
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+ ret = gpio_request_by_name(dev, "their-claim-gpios", 0, &priv->ec_claim,
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+ GPIOD_IS_IN);
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+ if (ret)
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+ goto err_ec_gpio;
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+
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+ return 0;
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+
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+err_ec_gpio:
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+ dm_gpio_free(dev, &priv->ap_claim);
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+err:
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+ debug("%s: ret=%d\n", __func__, ret);
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+ return ret;
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+}
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+
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+static int i2c_arbitrator_remove(struct udevice *dev)
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+{
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+ struct i2c_arbitrator_priv *priv = dev_get_priv(dev);
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+
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+ dm_gpio_free(dev, &priv->ap_claim);
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+ dm_gpio_free(dev, &priv->ec_claim);
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+
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+ return 0;
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+}
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+
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+static const struct i2c_mux_ops i2c_arbitrator_ops = {
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+ .select = i2c_arbitrator_select,
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+ .deselect = i2c_arbitrator_deselect,
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+};
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+
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+static const struct udevice_id i2c_arbitrator_ids[] = {
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+ { .compatible = "i2c-arb-gpio-challenge" },
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+ { }
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+};
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+
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+U_BOOT_DRIVER(i2c_arbitrator) = {
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+ .name = "i2c_arbitrator",
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+ .id = UCLASS_I2C_MUX,
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+ .of_match = i2c_arbitrator_ids,
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+ .probe = i2c_arbitrator_probe,
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+ .remove = i2c_arbitrator_remove,
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+ .ops = &i2c_arbitrator_ops,
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+ .priv_auto_alloc_size = sizeof(struct i2c_arbitrator_priv),
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+};
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