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/*
 * I2C multiplexer using pinctrl API
 *
 * Copyright (c) 2012, NVIDIA CORPORATION.  All rights reserved.
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms and conditions of the GNU General Public License,
 * version 2, as published by the Free Software Foundation.
 *
 * This program is distributed in the hope it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
 * more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

#include <linux/i2c.h>
#include <linux/i2c-mux.h>
#include <linux/module.h>
#include <linux/pinctrl/consumer.h>
#include <linux/i2c-mux-pinctrl.h>
#include <linux/platform_device.h>
#include <linux/slab.h>
#include <linux/of.h>
#include "../../pinctrl/core.h"

struct i2c_mux_pinctrl {
	struct i2c_mux_pinctrl_platform_data *pdata;
	struct pinctrl *pinctrl;
	struct pinctrl_state **states;
	struct pinctrl_state *state_idle;
};

static int i2c_mux_pinctrl_select(struct i2c_mux_core *muxc, u32 chan)
{
	struct i2c_mux_pinctrl *mux = i2c_mux_priv(muxc);

	return pinctrl_select_state(mux->pinctrl, mux->states[chan]);
}

static int i2c_mux_pinctrl_deselect(struct i2c_mux_core *muxc, u32 chan)
{
	struct i2c_mux_pinctrl *mux = i2c_mux_priv(muxc);

	return pinctrl_select_state(mux->pinctrl, mux->state_idle);
}

#ifdef CONFIG_OF
static int i2c_mux_pinctrl_parse_dt(struct i2c_mux_pinctrl *mux,
				    struct platform_device *pdev)
{
	struct device_node *np = pdev->dev.of_node;
	int num_names, i, ret;
	struct device_node *adapter_np;
	struct i2c_adapter *adapter;

	if (!np)
		return 0;

	mux->pdata = devm_kzalloc(&pdev->dev, sizeof(*mux->pdata), GFP_KERNEL);
	if (!mux->pdata)
		return -ENOMEM;

	num_names = of_property_count_strings(np, "pinctrl-names");
	if (num_names < 0) {
		dev_err(&pdev->dev, "Cannot parse pinctrl-names: %d\n",
			num_names);
		return num_names;
	}

	mux->pdata->pinctrl_states = devm_kzalloc(&pdev->dev,
		sizeof(*mux->pdata->pinctrl_states) * num_names,
		GFP_KERNEL);
	if (!mux->pdata->pinctrl_states)
		return -ENOMEM;

	for (i = 0; i < num_names; i++) {
		ret = of_property_read_string_index(np, "pinctrl-names", i,
			&mux->pdata->pinctrl_states[mux->pdata->bus_count]);
		if (ret < 0) {
			dev_err(&pdev->dev, "Cannot parse pinctrl-names: %d\n",
				ret);
			return ret;
		}
		if (!strcmp(mux->pdata->pinctrl_states[mux->pdata->bus_count],
			    "idle")) {
			if (i != num_names - 1) {
				dev_err(&pdev->dev,
					"idle state must be last\n");
				return -EINVAL;
			}
			mux->pdata->pinctrl_state_idle = "idle";
		} else {
			mux->pdata->bus_count++;
		}
	}

	adapter_np = of_parse_phandle(np, "i2c-parent", 0);
	if (!adapter_np) {
		dev_err(&pdev->dev, "Cannot parse i2c-parent\n");
		return -ENODEV;
	}
	adapter = of_find_i2c_adapter_by_node(adapter_np);
	of_node_put(adapter_np);
	if (!adapter) {
		dev_err(&pdev->dev, "Cannot find parent bus\n");
		return -EPROBE_DEFER;
	}
	mux->pdata->parent_bus_num = i2c_adapter_id(adapter);
	put_device(&adapter->dev);

	return 0;
}
#else
static inline int i2c_mux_pinctrl_parse_dt(struct i2c_mux_pinctrl *mux,
					   struct platform_device *pdev)
{
	return 0;
}
#endif

static struct i2c_adapter *i2c_mux_pinctrl_root_adapter(
	struct pinctrl_state *state)
{
	struct i2c_adapter *root = NULL;
	struct pinctrl_setting *setting;
	struct i2c_adapter *pin_root;

	list_for_each_entry(setting, &state->settings, node) {
		pin_root = i2c_root_adapter(setting->pctldev->dev);
		if (!pin_root)
			return NULL;
		if (!root)
			root = pin_root;
		else if (root != pin_root)
			return NULL;
	}

	return root;
}

static int i2c_mux_pinctrl_probe(struct platform_device *pdev)
{
	struct i2c_mux_core *muxc;
	struct i2c_mux_pinctrl *mux;
	struct i2c_adapter *root;
	int i, ret;

	mux = devm_kzalloc(&pdev->dev, sizeof(*mux), GFP_KERNEL);
	if (!mux) {
		ret = -ENOMEM;
		goto err;
	}

	mux->pdata = dev_get_platdata(&pdev->dev);
	if (!mux->pdata) {
		ret = i2c_mux_pinctrl_parse_dt(mux, pdev);
		if (ret < 0)
			goto err;
	}
	if (!mux->pdata) {
		dev_err(&pdev->dev, "Missing platform data\n");
		ret = -ENODEV;
		goto err;
	}

	mux->states = devm_kzalloc(&pdev->dev,
				   sizeof(*mux->states) * mux->pdata->bus_count,
				   GFP_KERNEL);
	if (!mux->states) {
		dev_err(&pdev->dev, "Cannot allocate states\n");
		ret = -ENOMEM;
		goto err;
	}

	muxc = i2c_mux_alloc(NULL, &pdev->dev, mux->pdata->bus_count, 0, 0,
			     i2c_mux_pinctrl_select, NULL);
	if (!muxc) {
		ret = -ENOMEM;
		goto err;
	}
	muxc->priv = mux;

	platform_set_drvdata(pdev, muxc);

	mux->pinctrl = devm_pinctrl_get(&pdev->dev);
	if (IS_ERR(mux->pinctrl)) {
		ret = PTR_ERR(mux->pinctrl);
		dev_err(&pdev->dev, "Cannot get pinctrl: %d\n", ret);
		goto err;
	}
	for (i = 0; i < mux->pdata->bus_count; i++) {
		mux->states[i] = pinctrl_lookup_state(mux->pinctrl,
						mux->pdata->pinctrl_states[i]);
		if (IS_ERR(mux->states[i])) {
			ret = PTR_ERR(mux->states[i]);
			dev_err(&pdev->dev,
				"Cannot look up pinctrl state %s: %d\n",
				mux->pdata->pinctrl_states[i], ret);
			goto err;
		}
	}
	if (mux->pdata->pinctrl_state_idle) {
		mux->state_idle = pinctrl_lookup_state(mux->pinctrl,
						mux->pdata->pinctrl_state_idle);
		if (IS_ERR(mux->state_idle)) {
			ret = PTR_ERR(mux->state_idle);
			dev_err(&pdev->dev,
				"Cannot look up pinctrl state %s: %d\n",
				mux->pdata->pinctrl_state_idle, ret);
			goto err;
		}

		muxc->deselect = i2c_mux_pinctrl_deselect;
	}

	muxc->parent = i2c_get_adapter(mux->pdata->parent_bus_num);
	if (!muxc->parent) {
		dev_err(&pdev->dev, "Parent adapter (%d) not found\n",
			mux->pdata->parent_bus_num);
		ret = -EPROBE_DEFER;
		goto err;
	}

	root = i2c_root_adapter(&muxc->parent->dev);

	muxc->mux_locked = true;
	for (i = 0; i < mux->pdata->bus_count; i++) {
		if (root != i2c_mux_pinctrl_root_adapter(mux->states[i])) {
			muxc->mux_locked = false;
			break;
		}
	}
	if (muxc->mux_locked && mux->pdata->pinctrl_state_idle &&
	    root != i2c_mux_pinctrl_root_adapter(mux->state_idle))
		muxc->mux_locked = false;

	if (muxc->mux_locked)
		dev_info(&pdev->dev, "mux-locked i2c mux\n");

	for (i = 0; i < mux->pdata->bus_count; i++) {
		u32 bus = mux->pdata->base_bus_num ?
				(mux->pdata->base_bus_num + i) : 0;

		ret = i2c_mux_add_adapter(muxc, bus, i, 0);
		if (ret)
			goto err_del_adapter;
	}

	return 0;

err_del_adapter:
	i2c_mux_del_adapters(muxc);
	i2c_put_adapter(muxc->parent);
err:
	return ret;
}

static int i2c_mux_pinctrl_remove(struct platform_device *pdev)
{
	struct i2c_mux_core *muxc = platform_get_drvdata(pdev);

	i2c_mux_del_adapters(muxc);
	i2c_put_adapter(muxc->parent);
	return 0;
}

#ifdef CONFIG_OF
static const struct of_device_id i2c_mux_pinctrl_of_match[] = {
	{ .compatible = "i2c-mux-pinctrl", },
	{},
};
MODULE_DEVICE_TABLE(of, i2c_mux_pinctrl_of_match);
#endif

static struct platform_driver i2c_mux_pinctrl_driver = {
	.driver	= {
		.name	= "i2c-mux-pinctrl",
		.of_match_table = of_match_ptr(i2c_mux_pinctrl_of_match),
	},
	.probe	= i2c_mux_pinctrl_probe,
	.remove	= i2c_mux_pinctrl_remove,
};
module_platform_driver(i2c_mux_pinctrl_driver);

MODULE_DESCRIPTION("pinctrl-based I2C multiplexer driver");
MODULE_AUTHOR("Stephen Warren <swarren@nvidia.com>");
MODULE_LICENSE("GPL v2");
MODULE_ALIAS("platform:i2c-mux-pinctrl");