/*
   * 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>
  
  struct i2c_mux_pinctrl {
  	struct device *dev;
  	struct i2c_mux_pinctrl_platform_data *pdata;
  	struct pinctrl *pinctrl;
  	struct pinctrl_state **states;
  	struct pinctrl_state *state_idle;
  	struct i2c_adapter *parent;
  	struct i2c_adapter **busses;
  };
  
  static int i2c_mux_pinctrl_select(struct i2c_adapter *adap, void *data,
  				  u32 chan)
  {
  	struct i2c_mux_pinctrl *mux = data;
  
  	return pinctrl_select_state(mux->pinctrl, mux->states[chan]);
  }
  
  static int i2c_mux_pinctrl_deselect(struct i2c_adapter *adap, void *data,
  				    u32 chan)
  {
  	struct i2c_mux_pinctrl *mux = data;
  
  	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) {
  		dev_err(mux->dev,
  			"Cannot allocate i2c_mux_pinctrl_platform_data
  ");
  		return -ENOMEM;
  	}
  
  	num_names = of_property_count_strings(np, "pinctrl-names");
  	if (num_names < 0) {
  		dev_err(mux->dev, "Cannot parse pinctrl-names: %d
  ",
  			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) {
  		dev_err(mux->dev, "Cannot allocate 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(mux->dev, "Cannot parse pinctrl-names: %d
  ",
  				ret);
  			return ret;
  		}
  		if (!strcmp(mux->pdata->pinctrl_states[mux->pdata->bus_count],
  			    "idle")) {
  			if (i != num_names - 1) {
  				dev_err(mux->dev, "idle state must be last
  ");
  				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(mux->dev, "Cannot parse i2c-parent
  ");
  		return -ENODEV;
  	}
  	adapter = of_find_i2c_adapter_by_node(adapter_np);
  	if (!adapter) {
  		dev_err(mux->dev, "Cannot find parent bus
  ");
  		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 int i2c_mux_pinctrl_probe(struct platform_device *pdev)
  {
  	struct i2c_mux_pinctrl *mux;
  	int (*deselect)(struct i2c_adapter *, void *, u32);
  	int i, ret;
  
  	mux = devm_kzalloc(&pdev->dev, sizeof(*mux), GFP_KERNEL);
  	if (!mux) {
  		dev_err(&pdev->dev, "Cannot allocate i2c_mux_pinctrl
  ");
  		ret = -ENOMEM;
  		goto err;
  	}
  	platform_set_drvdata(pdev, mux);
  
  	mux->dev = &pdev->dev;
  
  	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
  ");
  		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
  ");
  		ret = -ENOMEM;
  		goto err;
  	}
  
  	mux->busses = devm_kzalloc(&pdev->dev,
  				   sizeof(*mux->busses) * mux->pdata->bus_count,
  				   GFP_KERNEL);
  	if (!mux->busses) {
  		dev_err(&pdev->dev, "Cannot allocate busses
  ");
  		ret = -ENOMEM;
  		goto err;
  	}
  
  	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
  ", 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
  ",
  					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
  ",
  				mux->pdata->pinctrl_state_idle, ret);
  			goto err;
  		}
  
  		deselect = i2c_mux_pinctrl_deselect;
  	} else {
  		deselect = NULL;
  	}
  
  	mux->parent = i2c_get_adapter(mux->pdata->parent_bus_num);
  	if (!mux->parent) {
  		dev_err(&pdev->dev, "Parent adapter (%d) not found
  ",
  			mux->pdata->parent_bus_num);
  		ret = -EPROBE_DEFER;
  		goto err;
  	}
  
  	for (i = 0; i < mux->pdata->bus_count; i++) {
  		u32 bus = mux->pdata->base_bus_num ?
  				(mux->pdata->base_bus_num + i) : 0;
  
  		mux->busses[i] = i2c_add_mux_adapter(mux->parent, &pdev->dev,
  						     mux, bus, i, 0,
  						     i2c_mux_pinctrl_select,
  						     deselect);
  		if (!mux->busses[i]) {
  			ret = -ENODEV;
  			dev_err(&pdev->dev, "Failed to add adapter %d
  ", i);
  			goto err_del_adapter;
  		}
  	}
  
  	return 0;
  
  err_del_adapter:
  	for (; i > 0; i--)
  		i2c_del_mux_adapter(mux->busses[i - 1]);
  	i2c_put_adapter(mux->parent);
  err:
  	return ret;
  }
  
  static int i2c_mux_pinctrl_remove(struct platform_device *pdev)
  {
  	struct i2c_mux_pinctrl *mux = platform_get_drvdata(pdev);
  	int i;
  
  	for (i = 0; i < mux->pdata->bus_count; i++)
  		i2c_del_mux_adapter(mux->busses[i]);
  
  	i2c_put_adapter(mux->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",
  		.owner	= THIS_MODULE,
  		.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");