147 lines
3.3 KiB
C
147 lines
3.3 KiB
C
// SPDX-License-Identifier: GPL-2.0+
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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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#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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DECLARE_GLOBAL_DATA_PTR;
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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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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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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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return ret;
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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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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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/* 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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/* 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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if (!waiting)
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waiting = 1;
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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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mdelay(priv->wait_retry_ms);
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} while (get_timer(start) < priv->wait_free_ms);
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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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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(dev);
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int ret;
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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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return 0;
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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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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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dm_gpio_free(dev, &priv->ap_claim);
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dm_gpio_free(dev, &priv->ec_claim);
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return 0;
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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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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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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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