U-Boot

// SPDX-License-Identifier: GPL-2.0+
/*
 * Copyright (c) 2015 Google, Inc
 * Written by Simon Glass <sjg@chromium.org>
 */

#define LOG_CATEGORY UCLASS_I2C_MUX

#include <dm.h>
#include <errno.h>
#include <i2c.h>
#include <log.h>
#include <malloc.h>
#include <dm/lists.h>
#include <dm/root.h>

/**
 * struct i2c_mux: Information the uclass stores about an I2C mux
 *
 * @selected:	Currently selected mux, or -1 for none
 * @i2c_bus: I2C bus to use for communcation
 */
struct i2c_mux {
	int selected;
	struct udevice *i2c_bus;
};

/**
 * struct i2c_mux_bus: Information about each bus the mux controls
 *
 * @channel: Channel number used to select this bus
 */
struct i2c_mux_bus {
	uint channel;
};

/* Find out the mux channel number */
static int i2c_mux_child_post_bind(struct udevice *dev)
{
	struct i2c_mux_bus *plat = dev_get_parent_plat(dev);
	int channel;

	ofnode node = dev_ofnode(dev);

	if (!ofnode_has_property(node, "reg"))
		return 0;

	channel = dev_read_u32_default(dev, "reg", -1);
	if (channel < 0)
		return -EINVAL;
	plat->channel = channel;

	return 0;
}

/* Find the I2C buses selected by this mux */
static int i2c_mux_post_bind(struct udevice *mux)
{
	ofnode node;
	int ret;

	debug("%s: %s\n", __func__, mux->name);
	/*
	 * There is no compatible string in the sub-nodes, so we must manually
	 * bind these
	 */
	dev_for_each_subnode(node, mux) {
		struct udevice *dev;
		const char *name;
		const char *arrow = "->";
		char *full_name;
		int parent_name_len, arrow_len, mux_name_len, name_len;

		name = ofnode_get_name(node);

		/* Calculate lenghts of strings */
		parent_name_len = strlen(mux->parent->name);
		arrow_len = strlen(arrow);
		mux_name_len = strlen(mux->name);
		name_len = strlen(name);

		full_name = calloc(1, parent_name_len + arrow_len +
				   mux_name_len + arrow_len + name_len + 1);
		if (!full_name)
			return -ENOMEM;

		/* Compose bus name */
		strcat(full_name, mux->parent->name);
		strcat(full_name, arrow);
		strcat(full_name, mux->name);
		strcat(full_name, arrow);
		strcat(full_name, name);

		ret = device_bind_driver_to_node(mux, "i2c_mux_bus_drv",
						 full_name, node, &dev);
		debug("   - bind ret=%d, %s, seq %d\n", ret,
		      dev ? dev->name : NULL, dev_seq(dev));
		if (ret)
			return ret;
	}

	return 0;
}

/* Set up the mux ready for use */
static int i2c_mux_post_probe(struct udevice *mux)
{
	struct i2c_mux *priv = dev_get_uclass_priv(mux);
	int ret;

	debug("%s: %s\n", __func__, mux->name);
	priv->selected = -1;

	/* if parent is of i2c uclass already, we'll take that, otherwise
	 * look if we find an i2c-parent phandle
	 */
	if (UCLASS_I2C == device_get_uclass_id(mux->parent)) {
		priv->i2c_bus = dev_get_parent(mux);
		debug("%s: bus=%p/%s\n", __func__, priv->i2c_bus,
		      priv->i2c_bus->name);
		return 0;
	}

	ret = uclass_get_device_by_phandle(UCLASS_I2C, mux, "i2c-parent",
					   &priv->i2c_bus);
	if (ret)
		return ret;
	debug("%s: bus=%p/%s\n", __func__, priv->i2c_bus, priv->i2c_bus->name);

	return 0;
}

static int i2c_mux_select(struct udevice *dev)
{
	struct i2c_mux_bus *plat = dev_get_parent_plat(dev);
	struct udevice *mux = dev->parent;
	struct i2c_mux_ops *ops = i2c_mux_get_ops(mux);

	if (!ops->select)
		return -ENOSYS;

	return ops->select(mux, dev, plat->channel);
}

static int i2c_mux_deselect(struct udevice *dev)
{
	struct i2c_mux_bus *plat = dev_get_parent_plat(dev);
	struct udevice *mux = dev->parent;
	struct i2c_mux_ops *ops = i2c_mux_get_ops(mux);

	if (!ops->deselect)
		return -ENOSYS;

	return ops->deselect(mux, dev, plat->channel);
}

static int i2c_mux_bus_set_bus_speed(struct udevice *dev, unsigned int speed)
{
	struct udevice *mux = dev->parent;
	struct i2c_mux *priv = dev_get_uclass_priv(mux);
	int ret, ret2;

	ret = i2c_mux_select(dev);
	if (ret)
		return ret;
	ret = dm_i2c_set_bus_speed(priv->i2c_bus, speed);
	ret2 = i2c_mux_deselect(dev);

	return ret ? ret : ret2;
}

static int i2c_mux_bus_probe(struct udevice *dev, uint chip_addr,
			     uint chip_flags)
{
	struct udevice *mux = dev->parent;
	struct i2c_mux *priv = dev_get_uclass_priv(mux);
	struct dm_i2c_ops *ops = i2c_get_ops(priv->i2c_bus);
	int ret, ret2;

	debug("%s: %s, bus %s\n", __func__, dev->name, priv->i2c_bus->name);
	if (!ops->probe_chip)
		return -ENOSYS;
	ret = i2c_mux_select(dev);
	if (ret)
		return ret;
	ret = ops->probe_chip(priv->i2c_bus, chip_addr, chip_flags);
	ret2 = i2c_mux_deselect(dev);

	return ret ? ret : ret2;
}

static int i2c_mux_bus_xfer(struct udevice *dev, struct i2c_msg *msg,
			    int nmsgs)
{
	struct udevice *mux = dev->parent;
	struct i2c_mux *priv = dev_get_uclass_priv(mux);
	struct dm_i2c_ops *ops = i2c_get_ops(priv->i2c_bus);
	int ret, ret2;

	debug("%s: %s, bus %s\n", __func__, dev->name, priv->i2c_bus->name);
	if (!ops->xfer)
		return -ENOSYS;
	ret = i2c_mux_select(dev);
	if (ret)
		return ret;
	ret = ops->xfer(priv->i2c_bus, msg, nmsgs);
	ret2 = i2c_mux_deselect(dev);

	return ret ? ret : ret2;
}

static const struct dm_i2c_ops i2c_mux_bus_ops = {
	.xfer		= i2c_mux_bus_xfer,
	.probe_chip	= i2c_mux_bus_probe,
	.set_bus_speed	= i2c_mux_bus_set_bus_speed,
};

U_BOOT_DRIVER(i2c_mux_bus) = {
	.name		= "i2c_mux_bus_drv",
	.id		= UCLASS_I2C,
	.ops	= &i2c_mux_bus_ops,
};

UCLASS_DRIVER(i2c_mux) = {
	.id		= UCLASS_I2C_MUX,
	.name		= "i2c_mux",
	.post_bind	= i2c_mux_post_bind,
	.post_probe	= i2c_mux_post_probe,
	.per_device_auto	= sizeof(struct i2c_mux),
	.per_child_plat_auto	= sizeof(struct i2c_mux_bus),
	.child_post_bind = i2c_mux_child_post_bind,
};