/*
 * 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\n",
			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\n",
			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\n",
			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\n",
			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\n",
			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\n", 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\n", 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\n",
				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\n");
		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.\n");

	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");