/*
   * SCI Clock driver for keystone based devices
   *
   * Copyright (C) 2015-2016 Texas Instruments Incorporated - http://www.ti.com/
   *	Tero Kristo <t-kristo@ti.com>
   *
   * This program is free software; you can redistribute it and/or modify
   * it under the terms of the GNU General Public License version 2 as
   * published by the Free Software Foundation.
   *
   * This program is distributed "as is" WITHOUT ANY WARRANTY of any
   * kind, whether express or implied; without even the implied warranty
   * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   * GNU General Public License for more details.
   */
  #include <linux/clk.h>
  #include <linux/clk-provider.h>
  #include <linux/err.h>
  #include <linux/io.h>
  #include <linux/module.h>
  #include <linux/of_address.h>
  #include <linux/of.h>
  #include <linux/platform_device.h>
  #include <linux/slab.h>
  #include <linux/soc/ti/ti_sci_protocol.h>
  
  #define SCI_CLK_SSC_ENABLE		BIT(0)
  #define SCI_CLK_ALLOW_FREQ_CHANGE	BIT(1)
  #define SCI_CLK_INPUT_TERMINATION	BIT(2)
  
  /**
   * struct sci_clk_provider - TI SCI clock provider representation
   * @sci:    Handle to the System Control Interface protocol handler
   * @ops:    Pointer to the SCI ops to be used by the clocks
   * @dev:    Device pointer for the clock provider
   * @clocks: List of all registered clocks
   * @lock:   Mutex for locking access to the @clocks list
   */
  struct sci_clk_provider {
  	const struct ti_sci_handle *sci;
  	const struct ti_sci_clk_ops *ops;
  	struct device *dev;
  	struct list_head clocks;
  	struct mutex lock; /* Protects access to the @clocks list */
  };
  
  /**
   * struct sci_clk - TI SCI clock representation
   * @hw:		 Hardware clock cookie for common clock framework
   * @dev_id:	 Device index
   * @clk_id:	 Clock index
   * @node:	 Clocks list link
   * @provider:	 Master clock provider
   * @flags:	 Flags for the clock
   */
  struct sci_clk {
  	struct clk_hw hw;
  	u16 dev_id;
  	u8 clk_id;
  	struct list_head node;
  	struct sci_clk_provider *provider;
  	u8 flags;
  };
  
  #define to_sci_clk(_hw) container_of(_hw, struct sci_clk, hw)
  
  /**
   * sci_clk_prepare - Prepare (enable) a TI SCI clock
   * @hw: clock to prepare
   *
   * Prepares a clock to be actively used. Returns the SCI protocol status.
   */
  static int sci_clk_prepare(struct clk_hw *hw)
  {
  	struct sci_clk *clk = to_sci_clk(hw);
  	bool enable_ssc = clk->flags & SCI_CLK_SSC_ENABLE;
  	bool allow_freq_change = clk->flags & SCI_CLK_ALLOW_FREQ_CHANGE;
  	bool input_termination = clk->flags & SCI_CLK_INPUT_TERMINATION;
  
  	return clk->provider->ops->get_clock(clk->provider->sci, clk->dev_id,
  					     clk->clk_id, enable_ssc,
  					     allow_freq_change,
  					     input_termination);
  }
  
  /**
   * sci_clk_unprepare - Un-prepares (disables) a TI SCI clock
   * @hw: clock to unprepare
   *
   * Un-prepares a clock from active state.
   */
  static void sci_clk_unprepare(struct clk_hw *hw)
  {
  	struct sci_clk *clk = to_sci_clk(hw);
  	int ret;
  
  	ret = clk->provider->ops->put_clock(clk->provider->sci, clk->dev_id,
  					    clk->clk_id);
  	if (ret)
  		dev_err(clk->provider->dev,
  			"unprepare failed for dev=%d, clk=%d, ret=%d
  ",
  			clk->dev_id, clk->clk_id, ret);
  }
  
  /**
   * sci_clk_is_prepared - Check if a TI SCI clock is prepared or not
   * @hw: clock to check status for
   *
   * Checks if a clock is prepared (enabled) in hardware. Returns non-zero
   * value if clock is enabled, zero otherwise.
   */
  static int sci_clk_is_prepared(struct clk_hw *hw)
  {
  	struct sci_clk *clk = to_sci_clk(hw);
  	bool req_state, current_state;
  	int ret;
  
  	ret = clk->provider->ops->is_on(clk->provider->sci, clk->dev_id,
  					clk->clk_id, &req_state,
  					&current_state);
  	if (ret) {
  		dev_err(clk->provider->dev,
  			"prepare failed for dev=%d, clk=%d, ret=%d
  ",
  			clk->dev_id, clk->clk_id, ret);
  		return 0;
  	}
  
  	return req_state;
  }
  
  /**
   * sci_clk_recalc_rate - Get clock rate for a TI SCI clock
   * @hw: clock to get rate for
   * @parent_rate: parent rate provided by common clock framework, not used
   *
   * Gets the current clock rate of a TI SCI clock. Returns the current
   * clock rate, or zero in failure.
   */
  static unsigned long sci_clk_recalc_rate(struct clk_hw *hw,
  					 unsigned long parent_rate)
  {
  	struct sci_clk *clk = to_sci_clk(hw);
  	u64 freq;
  	int ret;
  
  	ret = clk->provider->ops->get_freq(clk->provider->sci, clk->dev_id,
  					   clk->clk_id, &freq);
  	if (ret) {
  		dev_err(clk->provider->dev,
  			"recalc-rate failed for dev=%d, clk=%d, ret=%d
  ",
  			clk->dev_id, clk->clk_id, ret);
  		return 0;
  	}
  
  	return (u32)freq;
  }
  
  /**
   * sci_clk_determine_rate - Determines a clock rate a clock can be set to
   * @hw: clock to change rate for
   * @req: requested rate configuration for the clock
   *
   * Determines a suitable clock rate and parent for a TI SCI clock.
   * The parent handling is un-used, as generally the parent clock rates
   * are not known by the kernel; instead these are internally handled
   * by the firmware. Returns 0 and sets the new rate in the req->rate field
   * on success, returns < 0 on failure.
   */
  static int sci_clk_determine_rate(struct clk_hw *hw,
  				  struct clk_rate_request *req)
  {
  	struct sci_clk *clk = to_sci_clk(hw);
  	u64 new_rate;
  	int ret;
  
  	ret = clk->provider->ops->get_best_match_freq(clk->provider->sci,
  						      clk->dev_id,
  						      clk->clk_id,
  						      req->min_rate,
  						      req->rate,
  						      req->max_rate,
  						      &new_rate);
  	if (ret) {
  		dev_err(clk->provider->dev,
  			"determine-rate failed for dev=%d, clk=%d, ret=%d
  ",
  			clk->dev_id, clk->clk_id, ret);
  		return ret;
  	}
  
  	req->rate = new_rate;
  
  	return 0;
  }
  
  /**
   * sci_clk_set_rate - Set rate for a TI SCI clock
   * @hw: clock to change rate for
   * @rate: target rate for the clock
   * @parent_rate: rate of the clock parent, not used for TI SCI clocks
   *
   * Sets a clock frequency for a TI SCI clock. Returns the TI SCI
   * protocol status.
   */
  static int sci_clk_set_rate(struct clk_hw *hw, unsigned long rate,
  			    unsigned long parent_rate)
  {
  	struct sci_clk *clk = to_sci_clk(hw);
  	u64 freq = rate;
  
  	return clk->provider->ops->set_freq(clk->provider->sci, clk->dev_id,
  					    clk->clk_id, freq, freq, freq);
  }
  
  /**
   * sci_clk_get_parent - Get the current parent of a TI SCI clock
   * @hw: clock to get parent for
   *
   * Returns the index of the currently selected parent for a TI SCI clock.
   */
  static u8 sci_clk_get_parent(struct clk_hw *hw)
  {
  	struct sci_clk *clk = to_sci_clk(hw);
  	u8 parent_id;
  	int ret;
  
  	ret = clk->provider->ops->get_parent(clk->provider->sci, clk->dev_id,
  					     clk->clk_id, &parent_id);
  	if (ret) {
  		dev_err(clk->provider->dev,
  			"get-parent failed for dev=%d, clk=%d, ret=%d
  ",
  			clk->dev_id, clk->clk_id, ret);
  		return 0;
  	}
  
  	parent_id = parent_id - clk->clk_id - 1;
  
  	return parent_id;
  }
  
  /**
   * sci_clk_set_parent - Set the parent of a TI SCI clock
   * @hw: clock to set parent for
   * @index: new parent index for the clock
   *
   * Sets the parent of a TI SCI clock. Return TI SCI protocol status.
   */
  static int sci_clk_set_parent(struct clk_hw *hw, u8 index)
  {
  	struct sci_clk *clk = to_sci_clk(hw);
  
  	return clk->provider->ops->set_parent(clk->provider->sci, clk->dev_id,
  					      clk->clk_id,
  					      index + 1 + clk->clk_id);
  }
  
  static const struct clk_ops sci_clk_ops = {
  	.prepare = sci_clk_prepare,
  	.unprepare = sci_clk_unprepare,
  	.is_prepared = sci_clk_is_prepared,
  	.recalc_rate = sci_clk_recalc_rate,
  	.determine_rate = sci_clk_determine_rate,
  	.set_rate = sci_clk_set_rate,
  	.get_parent = sci_clk_get_parent,
  	.set_parent = sci_clk_set_parent,
  };
  
  /**
   * _sci_clk_get - Gets a handle for an SCI clock
   * @provider: Handle to SCI clock provider
   * @dev_id: device ID for the clock to register
   * @clk_id: clock ID for the clock to register
   * @parse_parents: indicator whether parents for this clock should be handled
   *
   * Gets a handle to an existing TI SCI clock, or builds a new clock
   * entry and registers it with the common clock framework. Called from
   * the common clock framework, when a corresponding of_clk_get call is
   * executed, or recursively from itself when parsing parent clocks.
   * Returns a pointer to the clock struct, or ERR_PTR value in failure.
   */
  static struct clk *_sci_clk_get(struct sci_clk_provider *provider,
  				u16 dev_id, u8 clk_id, bool parse_parents)
  {
  	struct clk_init_data init = { NULL };
  	struct clk *clk;
  	struct sci_clk *sci_clk = NULL;
  	char name[20];
  	char **parent_names = NULL;
  	int i;
  	int ret;
  
  	list_for_each_entry(sci_clk, &provider->clocks, node)
  		if (sci_clk->dev_id == dev_id && sci_clk->clk_id == clk_id)
  			return sci_clk->hw.clk;
  
  	sci_clk = devm_kzalloc(provider->dev, sizeof(*sci_clk), GFP_KERNEL);
  	if (!sci_clk) {
  		ret = -ENOMEM;
  		goto err;
  	}
  
  	sci_clk->dev_id = dev_id;
  	sci_clk->clk_id = clk_id;
  	sci_clk->provider = provider;
  
  	if (parse_parents) {
  		ret = provider->ops->get_num_parents(provider->sci, dev_id,
  						     clk_id,
  						     &init.num_parents);
  		if (ret)
  			goto err;
  	}
  
  	snprintf(name, 20, "%s:%d:%d", dev_name(provider->dev), sci_clk->dev_id,
  		 sci_clk->clk_id);
  
  	init.name = name;
  
  	if (init.num_parents < 2) {
  		init.num_parents = 0;
  		init.flags = CLK_IS_ROOT;
  	}
  
  	if (init.num_parents) {
  		parent_names = devm_kcalloc(provider->dev, init.num_parents,
  					    sizeof(char *), GFP_KERNEL);
  
  		if (!parent_names) {
  			ret = -ENOMEM;
  			goto err;
  		}
  
  		for (i = 0; i < init.num_parents; i++) {
  			char *parent_name;
  
  			parent_name = devm_kzalloc(provider->dev, 20,
  						   GFP_KERNEL);
  			if (!parent_name) {
  				ret = -ENOMEM;
  				goto err;
  			}
  			snprintf(parent_name, 20, "%s:%d:%d",
  				 dev_name(provider->dev), sci_clk->dev_id,
  				 sci_clk->clk_id + 1 + i);
  			parent_names[i] = parent_name;
  
  			_sci_clk_get(provider, dev_id, clk_id + 1 + i, false);
  		}
  		init.parent_names = (const char * const *)parent_names;
  	}
  
  	init.ops = &sci_clk_ops;
  	sci_clk->hw.init = &init;
  
  	clk = devm_clk_register(provider->dev, &sci_clk->hw);
  
  	if (IS_ERR(clk)) {
  		ret = PTR_ERR(clk);
  		dev_err(provider->dev, "failed clk register with %d
  ", ret);
  		goto err;
  	} else {
  		list_add(&sci_clk->node, &provider->clocks);
  	}
  
  	return clk;
  
  err:
  	if (parent_names) {
  		for (i = 0; i < init.num_parents; i++)
  			devm_kfree(provider->dev, parent_names[i]);
  
  		devm_kfree(provider->dev, parent_names);
  	}
  
  	devm_kfree(provider->dev, sci_clk);
  
  	return ERR_PTR(ret);
  }
  
  /**
   * sci_clk_get - Xlate function for getting clock handles
   * @clkspec: device tree clock specifier
   * @data: pointer to the clock provider
   *
   * Xlate function for retrieving clock TI SCI clock handles based on
   * device tree clock specifier. Called from the common clock framework,
   * when a corresponding of_clk_get call is executed. Returns a pointer
   * to the TI SCI clock struct, or ERR_PTR value in failure.
   */
  static struct clk *sci_clk_get(struct of_phandle_args *clkspec, void *data)
  {
  	struct sci_clk_provider *provider = data;
  	struct clk *clk;
  	u16 dev_id;
  	u8 clk_id;
  
  	if (clkspec->args_count != 2)
  		return ERR_PTR(-EINVAL);
  
  	mutex_lock(&provider->lock);
  
  	dev_id = clkspec->args[0];
  	clk_id = clkspec->args[1];
  
  	clk = _sci_clk_get(provider, dev_id, clk_id, true);
  
  	mutex_unlock(&provider->lock);
  
  	return clk;
  }
  
  static const struct of_device_id ti_sci_clk_of_match[] = {
  	{ .compatible = "ti,sci-clk" },
  	{ /* Sentinel */ },
  };
  MODULE_DEVICE_TABLE(of, ti_sci_clk_of_match);
  
  /**
   * ti_sci_clk_parse_flags - Helper function to parse clock flag arrays
   * @dev: clock provider device
   * @np: device node pointer for the clock provider
   * @list_name: property name containing the clocks list
   * @flag: flag to apply to the list of clocks
   *
   * Parses a DT list based on the provided data, and applies the flag value
   * for each of the clocks identified by the list. Return 0 for success,
   * negative error value for failure.
   */
  static int ti_sci_clk_parse_flags(struct device *dev, struct device_node *np,
  				  const char *list_name, u8 flag)
  {
  	int num_clks;
  	int i;
  
  	num_clks = of_count_phandle_with_args(np, list_name, "#clock-cells");
  
  	for (i = 0; i < num_clks; i++) {
  		struct of_phandle_args clkspec;
  		struct clk_hw *hw;
  		struct sci_clk *sci_clk;
  		struct clk *clk;
  		int ret;
  
  		ret = of_parse_phandle_with_args(np, list_name, "#clock-cells",
  						 i, &clkspec);
  		if (ret) {
  			dev_err(dev, "Failed to parse %s[%d] = %d
  ", list_name,
  				i, ret);
  			return ret;
  		}
  		clk = of_clk_get_from_provider(&clkspec);
  		if (IS_ERR(clk)) {
  			dev_err(dev, "clk_get failed for %s[%d] = %ld
  ",
  				list_name, i, PTR_ERR(clk));
  			return PTR_ERR(clk);
  		}
  		hw = __clk_get_hw(clk);
  		sci_clk = to_sci_clk(hw);
  
  		sci_clk->flags |= flag;
  	}
  
  	return 0;
  }
  
  /**
   * ti_sci_clk_probe - Probe function for the TI SCI clock driver
   * @pdev: platform device pointer to be probed
   *
   * Probes the TI SCI clock device. Allocates a new clock provider
   * and registers this to the common clock framework. Also applies
   * any required flags to the identified clocks via clock lists
   * supplied from DT. Returns 0 for success, negative error value
   * for failure.
   */
  static int ti_sci_clk_probe(struct platform_device *pdev)
  {
  	struct device *dev = &pdev->dev;
  	struct device_node *np = dev->of_node;
  	struct sci_clk_provider *provider;
  	const struct ti_sci_handle *handle;
  
  	if (!np) {
  		dev_err(dev, "OF data missing
  ");
  		return -EINVAL;
  	}
  
  	handle = devm_ti_sci_get_handle(dev);
  	if (IS_ERR(handle))
  		return PTR_ERR(handle);
  
  	provider = devm_kzalloc(dev, sizeof(*provider), GFP_KERNEL);
  	if (!provider)
  		return -ENOMEM;
  
  	INIT_LIST_HEAD(&provider->clocks);
  	mutex_init(&provider->lock);
  
  	provider->sci = handle;
  	provider->ops = &handle->ops.clk_ops;
  	provider->dev = dev;
  
  	of_clk_add_provider(np, sci_clk_get, provider);
  
  	ti_sci_clk_parse_flags(dev, np, "ti,ssc-clocks", SCI_CLK_SSC_ENABLE);
  	ti_sci_clk_parse_flags(dev, np, "ti,allow-freq-change-clocks",
  			       SCI_CLK_ALLOW_FREQ_CHANGE);
  	ti_sci_clk_parse_flags(dev, np, "ti,input-term-clocks",
  			       SCI_CLK_INPUT_TERMINATION);
  
  	dev_info(dev, "initialized.
  ");
  
  	return 0;
  }
  
  /**
   * ti_sci_clk_remove - Remove TI SCI clock device
   * @pdev: platform device pointer for the device to be removed
   *
   * Removes the TI SCI device. Unregisters the clock provider registered
   * via common clock framework. Any memory allocated for the device will
   * be free'd silently via the devm framework. Returns 0 always.
   */
  static int ti_sci_clk_remove(struct platform_device *pdev)
  {
  	of_clk_del_provider(pdev->dev.of_node);
  
  	return 0;
  }
  
  static struct platform_driver ti_sci_clk_driver = {
  	.probe = ti_sci_clk_probe,
  	.remove = ti_sci_clk_remove,
  	.driver = {
  		.name = "ti-sci-clk",
  		.of_match_table = of_match_ptr(ti_sci_clk_of_match),
  	},
  };
  module_platform_driver(ti_sci_clk_driver);
  
  MODULE_LICENSE("GPL v2");
  MODULE_DESCRIPTION("TI System Control Interface(SCI) Clock driver");
  MODULE_AUTHOR("Tero Kristo");
  MODULE_ALIAS("platform:ti-sci-clk");