text: /*
   * 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) {
  			dev_err(&pdev->dev, "Failed to add adapter %d\n", i);
  			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");
  