[people/ms/u-boot.git] / drivers / i2c / muxes / i2c-arb-gpio-challenge.c

/*
 * 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(dev);
	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),
};
Commit	Line	Data
b725dc45 SG	1	/*
	2	* Copyright (c) 2015 Google, Inc
	3	* Written by Simon Glass <sjg@chromium.org>
	4	*
	5	* SPDX-License-Identifier: GPL-2.0+
	6	*/
	7
	8	#include <common.h>
	9	#include <dm.h>
	10	#include <errno.h>
	11	#include <i2c.h>
	12	#include <asm/gpio.h>
	13
	14	DECLARE_GLOBAL_DATA_PTR;
	15
	16	struct i2c_arbitrator_priv {
	17	struct gpio_desc ap_claim;
	18	struct gpio_desc ec_claim;
	19	uint slew_delay_us;
	20	uint wait_retry_ms;
	21	uint wait_free_ms;
	22	};
	23
	24	int i2c_arbitrator_deselect(struct udevice mux, struct udevice bus,
	25	uint channel)
	26	{
	27	struct i2c_arbitrator_priv *priv = dev_get_priv(mux);
	28	int ret;
	29
	30	debug("%s: %s\n", __func__, mux->name);
	31	ret = dm_gpio_set_value(&priv->ap_claim, 0);
	32	udelay(priv->slew_delay_us);
	33
	34	return ret;
	35	}
	36
	37	int i2c_arbitrator_select(struct udevice mux, struct udevice bus,
	38	uint channel)
	39	{
	40	struct i2c_arbitrator_priv *priv = dev_get_priv(mux);
	41	unsigned start;
	42	int ret;
	43
	44	debug("%s: %s\n", __func__, mux->name);
	45	/* Start a round of trying to claim the bus */
	46	start = get_timer(0);
	47	do {
	48	unsigned start_retry;
	49	int waiting = 0;
	50
	51	/* Indicate that we want to claim the bus */
	52	ret = dm_gpio_set_value(&priv->ap_claim, 1);
	53	if (ret)
	54	goto err;
	55	udelay(priv->slew_delay_us);
	56
	57	/* Wait for the EC to release it */
	58	start_retry = get_timer(0);
	59	while (get_timer(start_retry) < priv->wait_retry_ms) {
	60	ret = dm_gpio_get_value(&priv->ec_claim);
	61	if (ret < 0) {
	62	goto err;
	63	} else if (!ret) {
	64	/* We got it, so return */
65	return 0;
66	}
67
68	if (!waiting)
69	waiting = 1;
70	}
71
72	/* It didn't release, so give up, wait, and try again */
73	ret = dm_gpio_set_value(&priv->ap_claim, 0);
74	if (ret)
75	goto err;
76
77	mdelay(priv->wait_retry_ms);
78	} while (get_timer(start) < priv->wait_free_ms);
79
80	/* Give up, release our claim */
81	printf("I2C: Could not claim bus, timeout %lu\n", get_timer(start));
82	ret = -ETIMEDOUT;
83	ret = 0;
84	err:
85	return ret;
86	}
87
88	static int i2c_arbitrator_probe(struct udevice *dev)
89	{
90	struct i2c_arbitrator_priv *priv = dev_get_priv(dev);
91	const void *blob = gd->fdt_blob;
e160f7d4	92	int node = dev_of_offset(dev);
b725dc45 SG	93	int ret;
	94
	95	debug("%s: %s\n", __func__, dev->name);
	96	priv->slew_delay_us = fdtdec_get_int(blob, node, "slew-delay-us", 0);
	97	priv->wait_retry_ms = fdtdec_get_int(blob, node, "wait-retry-us", 0) /
	98	1000;
	99	priv->wait_free_ms = fdtdec_get_int(blob, node, "wait-free-us", 0) /
	100	1000;
	101	ret = gpio_request_by_name(dev, "our-claim-gpio", 0, &priv->ap_claim,
	102	GPIOD_IS_OUT);
	103	if (ret)
	104	goto err;
	105	ret = gpio_request_by_name(dev, "their-claim-gpios", 0, &priv->ec_claim,
	106	GPIOD_IS_IN);
	107	if (ret)
	108	goto err_ec_gpio;
	109
	110	return 0;
	111
	112	err_ec_gpio:
	113	dm_gpio_free(dev, &priv->ap_claim);
	114	err:
	115	debug("%s: ret=%d\n", __func__, ret);
	116	return ret;
	117	}
	118
	119	static int i2c_arbitrator_remove(struct udevice *dev)
	120	{
	121	struct i2c_arbitrator_priv *priv = dev_get_priv(dev);
	122
	123	dm_gpio_free(dev, &priv->ap_claim);
	124	dm_gpio_free(dev, &priv->ec_claim);
	125
	126	return 0;
	127	}
	128
	129	static const struct i2c_mux_ops i2c_arbitrator_ops = {
	130	.select = i2c_arbitrator_select,
	131	.deselect = i2c_arbitrator_deselect,
	132	};
	133
	134	static const struct udevice_id i2c_arbitrator_ids[] = {
	135	{ .compatible = "i2c-arb-gpio-challenge" },
	136	{ }
	137	};
	138
	139	U_BOOT_DRIVER(i2c_arbitrator) = {
	140	.name = "i2c_arbitrator",
	141	.id = UCLASS_I2C_MUX,
	142	.of_match = i2c_arbitrator_ids,
	143	.probe = i2c_arbitrator_probe,
	144	.remove = i2c_arbitrator_remove,
	145	.ops = &i2c_arbitrator_ops,
	146	.priv_auto_alloc_size = sizeof(struct i2c_arbitrator_priv),
	147	};