/*
 * Generic OPP OF helpers
 *
 * Copyright (C) 2009-2010 Texas Instruments Incorporated.
 *	Nishanth Menon
 *	Romit Dasgupta
 *	Kevin Hilman
 *
 * 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.
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/cpu.h>
#include <linux/errno.h>
#include <linux/device.h>
#include <linux/of.h>
#include <linux/export.h>

#include "opp.h"

static struct opp_table *_managed_opp(const struct device_node *np)
{
	struct opp_table *opp_table;

	list_for_each_entry_rcu(opp_table, &opp_tables, node) {
		if (opp_table->np == np) {
			/*
			 * Multiple devices can point to the same OPP table and
			 * so will have same node-pointer, np.
			 *
			 * But the OPPs will be considered as shared only if the
			 * OPP table contains a "opp-shared" property.
			 */
			return opp_table->shared_opp ? opp_table : NULL;
		}
	}

	return NULL;
}

void _of_init_opp_table(struct opp_table *opp_table, struct device *dev)
{
	struct device_node *np;

	/*
	 * Only required for backward compatibility with v1 bindings, but isn't
	 * harmful for other cases. And so we do it unconditionally.
	 */
	np = of_node_get(dev->of_node);
	if (np) {
		u32 val;

		if (!of_property_read_u32(np, "clock-latency", &val))
			opp_table->clock_latency_ns_max = val;
		of_property_read_u32(np, "voltage-tolerance",
				     &opp_table->voltage_tolerance_v1);
		of_node_put(np);
	}
}

static bool _opp_is_supported(struct device *dev, struct opp_table *opp_table,
			      struct device_node *np)
{
	unsigned int count = opp_table->supported_hw_count;
	u32 version;
	int ret;

	if (!opp_table->supported_hw)
		return true;

	while (count--) {
		ret = of_property_read_u32_index(np, "opp-supported-hw", count,
						 &version);
		if (ret) {
			dev_warn(dev, "%s: failed to read opp-supported-hw property at index %d: %d\n",
				 __func__, count, ret);
			return false;
		}

		/* Both of these are bitwise masks of the versions */
		if (!(version & opp_table->supported_hw[count]))
			return false;
	}

	return true;
}

/* TODO: Support multiple regulators */
static int opp_parse_supplies(struct dev_pm_opp *opp, struct device *dev,
			      struct opp_table *opp_table)
{
	u32 microvolt[3] = {0};
	u32 val;
	int count, ret;
	struct property *prop = NULL;
	char name[NAME_MAX];

	/* Search for "opp-microvolt-<name>" */
	if (opp_table->prop_name) {
		snprintf(name, sizeof(name), "opp-microvolt-%s",
			 opp_table->prop_name);
		prop = of_find_property(opp->np, name, NULL);
	}

	if (!prop) {
		/* Search for "opp-microvolt" */
		sprintf(name, "opp-microvolt");
		prop = of_find_property(opp->np, name, NULL);

		/* Missing property isn't a problem, but an invalid entry is */
		if (!prop)
			return 0;
	}

	count = of_property_count_u32_elems(opp->np, name);
	if (count < 0) {
		dev_err(dev, "%s: Invalid %s property (%d)\n",
			__func__, name, count);
		return count;
	}

	/* There can be one or three elements here */
	if (count != 1 && count != 3) {
		dev_err(dev, "%s: Invalid number of elements in %s property (%d)\n",
			__func__, name, count);
		return -EINVAL;
	}

	ret = of_property_read_u32_array(opp->np, name, microvolt, count);
	if (ret) {
		dev_err(dev, "%s: error parsing %s: %d\n", __func__, name, ret);
		return -EINVAL;
	}

	opp->u_volt = microvolt[0];

	if (count == 1) {
		opp->u_volt_min = opp->u_volt;
		opp->u_volt_max = opp->u_volt;
	} else {
		opp->u_volt_min = microvolt[1];
		opp->u_volt_max = microvolt[2];
	}

	/* Search for "opp-microamp-<name>" */
	prop = NULL;
	if (opp_table->prop_name) {
		snprintf(name, sizeof(name), "opp-microamp-%s",
			 opp_table->prop_name);
		prop = of_find_property(opp->np, name, NULL);
	}

	if (!prop) {
		/* Search for "opp-microamp" */
		sprintf(name, "opp-microamp");
		prop = of_find_property(opp->np, name, NULL);
	}

	if (prop && !of_property_read_u32(opp->np, name, &val))
		opp->u_amp = val;

	return 0;
}

/**
 * dev_pm_opp_of_remove_table() - Free OPP table entries created from static DT
 *				  entries
 * @dev:	device pointer used to lookup OPP table.
 *
 * Free OPPs created using static entries present in DT.
 *
 * Locking: The internal opp_table and opp structures are RCU protected.
 * Hence this function indirectly uses RCU updater strategy with mutex locks
 * to keep the integrity of the internal data structures. Callers should ensure
 * that this function is *NOT* called under RCU protection or in contexts where
 * mutex cannot be locked.
 */
void dev_pm_opp_of_remove_table(struct device *dev)
{
	_dev_pm_opp_remove_table(dev, false);
}
EXPORT_SYMBOL_GPL(dev_pm_opp_of_remove_table);

/* Returns opp descriptor node for a device, caller must do of_node_put() */
struct device_node *_of_get_opp_desc_node(struct device *dev)
{
	/*
	 * TODO: Support for multiple OPP tables.
	 *
	 * There should be only ONE phandle present in "operating-points-v2"
	 * property.
	 */

	return of_parse_phandle(dev->of_node, "operating-points-v2", 0);
}

/**
 * _opp_add_static_v2() - Allocate static OPPs (As per 'v2' DT bindings)
 * @dev:	device for which we do this operation
 * @np:		device node
 *
 * This function adds an opp definition to the opp table and returns status. The
 * opp can be controlled using dev_pm_opp_enable/disable functions and may be
 * removed by dev_pm_opp_remove.
 *
 * Locking: The internal opp_table and opp structures are RCU protected.
 * Hence this function internally uses RCU updater strategy with mutex locks
 * to keep the integrity of the internal data structures. Callers should ensure
 * that this function is *NOT* called under RCU protection or in contexts where
 * mutex cannot be locked.
 *
 * Return:
 * 0		On success OR
 *		Duplicate OPPs (both freq and volt are same) and opp->available
 * -EEXIST	Freq are same and volt are different OR
 *		Duplicate OPPs (both freq and volt are same) and !opp->available
 * -ENOMEM	Memory allocation failure
 * -EINVAL	Failed parsing the OPP node
 */
static int _opp_add_static_v2(struct device *dev, struct device_node *np)
{
	struct opp_table *opp_table;
	struct dev_pm_opp *new_opp;
	u64 rate;
	u32 val;
	int ret;

	/* Hold our table modification lock here */
	mutex_lock(&opp_table_lock);

	new_opp = _allocate_opp(dev, &opp_table);
	if (!new_opp) {
		ret = -ENOMEM;
		goto unlock;
	}

	ret = of_property_read_u64(np, "opp-hz", &rate);
	if (ret < 0) {
		dev_err(dev, "%s: opp-hz not found\n", __func__);
		goto free_opp;
	}

	/* Check if the OPP supports hardware's hierarchy of versions or not */
	if (!_opp_is_supported(dev, opp_table, np)) {
		dev_dbg(dev, "OPP not supported by hardware: %llu\n", rate);
		goto free_opp;
	}

	/*
	 * Rate is defined as an unsigned long in clk API, and so casting
	 * explicitly to its type. Must be fixed once rate is 64 bit
	 * guaranteed in clk API.
	 */
	new_opp->rate = (unsigned long)rate;
	new_opp->turbo = of_property_read_bool(np, "turbo-mode");

	new_opp->np = np;
	new_opp->dynamic = false;
	new_opp->available = true;

	if (!of_property_read_u32(np, "clock-latency-ns", &val))
		new_opp->clock_latency_ns = val;

	ret = opp_parse_supplies(new_opp, dev, opp_table);
	if (ret)
		goto free_opp;

	ret = _opp_add(dev, new_opp, opp_table);
	if (ret)
		goto free_opp;

	/* OPP to select on device suspend */
	if (of_property_read_bool(np, "opp-suspend")) {
		if (opp_table->suspend_opp) {
			dev_warn(dev, "%s: Multiple suspend OPPs found (%lu %lu)\n",
				 __func__, opp_table->suspend_opp->rate,
				 new_opp->rate);
		} else {
			new_opp->suspend = true;
			opp_table->suspend_opp = new_opp;
		}
	}

	if (new_opp->clock_latency_ns > opp_table->clock_latency_ns_max)
		opp_table->clock_latency_ns_max = new_opp->clock_latency_ns;

	mutex_unlock(&opp_table_lock);

	pr_debug("%s: turbo:%d rate:%lu uv:%lu uvmin:%lu uvmax:%lu latency:%lu\n",
		 __func__, new_opp->turbo, new_opp->rate, new_opp->u_volt,
		 new_opp->u_volt_min, new_opp->u_volt_max,
		 new_opp->clock_latency_ns);

	/*
	 * Notify the changes in the availability of the operable
	 * frequency/voltage list.
	 */
	srcu_notifier_call_chain(&opp_table->srcu_head, OPP_EVENT_ADD, new_opp);
	return 0;

free_opp:
	_opp_remove(opp_table, new_opp, false);
unlock:
	mutex_unlock(&opp_table_lock);
	return ret;
}

/* Initializes OPP tables based on new bindings */
static int _of_add_opp_table_v2(struct device *dev, struct device_node *opp_np)
{
	struct device_node *np;
	struct opp_table *opp_table;
	int ret = 0, count = 0;

	mutex_lock(&opp_table_lock);

	opp_table = _managed_opp(opp_np);
	if (opp_table) {
		/* OPPs are already managed */
		if (!_add_opp_dev(dev, opp_table))
			ret = -ENOMEM;
		mutex_unlock(&opp_table_lock);
		return ret;
	}
	mutex_unlock(&opp_table_lock);

	/* We have opp-table node now, iterate over it and add OPPs */
	for_each_available_child_of_node(opp_np, np) {
		count++;

		ret = _opp_add_static_v2(dev, np);
		if (ret) {
			dev_err(dev, "%s: Failed to add OPP, %d\n", __func__,
				ret);
			goto free_table;
		}
	}

	/* There should be one of more OPP defined */
	if (WARN_ON(!count))
		return -ENOENT;

	mutex_lock(&opp_table_lock);

	opp_table = _find_opp_table(dev);
	if (WARN_ON(IS_ERR(opp_table))) {
		ret = PTR_ERR(opp_table);
		mutex_unlock(&opp_table_lock);
		goto free_table;
	}

	opp_table->np = opp_np;
	opp_table->shared_opp = of_property_read_bool(opp_np, "opp-shared");

	mutex_unlock(&opp_table_lock);

	return 0;

free_table:
	dev_pm_opp_of_remove_table(dev);

	return ret;
}

/* Initializes OPP tables based on old-deprecated bindings */
static int _of_add_opp_table_v1(struct device *dev)
{
	const struct property *prop;
	const __be32 *val;
	int nr;

	prop = of_find_property(dev->of_node, "operating-points", NULL);
	if (!prop)
		return -ENODEV;
	if (!prop->value)
		return -ENODATA;

	/*
	 * Each OPP is a set of tuples consisting of frequency and
	 * voltage like <freq-kHz vol-uV>.
	 */
	nr = prop->length / sizeof(u32);
	if (nr % 2) {
		dev_err(dev, "%s: Invalid OPP table\n", __func__);
		return -EINVAL;
	}

	val = prop->value;
	while (nr) {
		unsigned long freq = be32_to_cpup(val++) * 1000;
		unsigned long volt = be32_to_cpup(val++);

		if (_opp_add_v1(dev, freq, volt, false))
			dev_warn(dev, "%s: Failed to add OPP %ld\n",
				 __func__, freq);
		nr -= 2;
	}

	return 0;
}

/**
 * dev_pm_opp_of_add_table() - Initialize opp table from device tree
 * @dev:	device pointer used to lookup OPP table.
 *
 * Register the initial OPP table with the OPP library for given device.
 *
 * Locking: The internal opp_table and opp structures are RCU protected.
 * Hence this function indirectly uses RCU updater strategy with mutex locks
 * to keep the integrity of the internal data structures. Callers should ensure
 * that this function is *NOT* called under RCU protection or in contexts where
 * mutex cannot be locked.
 *
 * Return:
 * 0		On success OR
 *		Duplicate OPPs (both freq and volt are same) and opp->available
 * -EEXIST	Freq are same and volt are different OR
 *		Duplicate OPPs (both freq and volt are same) and !opp->available
 * -ENOMEM	Memory allocation failure
 * -ENODEV	when 'operating-points' property is not found or is invalid data
 *		in device node.
 * -ENODATA	when empty 'operating-points' property is found
 * -EINVAL	when invalid entries are found in opp-v2 table
 */
int dev_pm_opp_of_add_table(struct device *dev)
{
	struct device_node *opp_np;
	int ret;

	/*
	 * OPPs have two version of bindings now. The older one is deprecated,
	 * try for the new binding first.
	 */
	opp_np = _of_get_opp_desc_node(dev);
	if (!opp_np) {
		/*
		 * Try old-deprecated bindings for backward compatibility with
		 * older dtbs.
		 */
		return _of_add_opp_table_v1(dev);
	}

	ret = _of_add_opp_table_v2(dev, opp_np);
	of_node_put(opp_np);

	return ret;
}
EXPORT_SYMBOL_GPL(dev_pm_opp_of_add_table);

/* CPU device specific helpers */

/**
 * dev_pm_opp_of_cpumask_remove_table() - Removes OPP table for @cpumask
 * @cpumask:	cpumask for which OPP table needs to be removed
 *
 * This removes the OPP tables for CPUs present in the @cpumask.
 * This should be used only to remove static entries created from DT.
 *
 * Locking: The internal opp_table and opp structures are RCU protected.
 * Hence this function internally uses RCU updater strategy with mutex locks
 * to keep the integrity of the internal data structures. Callers should ensure
 * that this function is *NOT* called under RCU protection or in contexts where
 * mutex cannot be locked.
 */
void dev_pm_opp_of_cpumask_remove_table(const struct cpumask *cpumask)
{
	_dev_pm_opp_cpumask_remove_table(cpumask, true);
}
EXPORT_SYMBOL_GPL(dev_pm_opp_of_cpumask_remove_table);

/**
 * dev_pm_opp_of_cpumask_add_table() - Adds OPP table for @cpumask
 * @cpumask:	cpumask for which OPP table needs to be added.
 *
 * This adds the OPP tables for CPUs present in the @cpumask.
 *
 * Locking: The internal opp_table and opp structures are RCU protected.
 * Hence this function internally uses RCU updater strategy with mutex locks
 * to keep the integrity of the internal data structures. Callers should ensure
 * that this function is *NOT* called under RCU protection or in contexts where
 * mutex cannot be locked.
 */
int dev_pm_opp_of_cpumask_add_table(const struct cpumask *cpumask)
{
	struct device *cpu_dev;
	int cpu, ret = 0;

	WARN_ON(cpumask_empty(cpumask));

	for_each_cpu(cpu, cpumask) {
		cpu_dev = get_cpu_device(cpu);
		if (!cpu_dev) {
			pr_err("%s: failed to get cpu%d device\n", __func__,
			       cpu);
			continue;
		}

		ret = dev_pm_opp_of_add_table(cpu_dev);
		if (ret) {
			pr_err("%s: couldn't find opp table for cpu:%d, %d\n",
			       __func__, cpu, ret);

			/* Free all other OPPs */
			dev_pm_opp_of_cpumask_remove_table(cpumask);
			break;
		}
	}

	return ret;
}
EXPORT_SYMBOL_GPL(dev_pm_opp_of_cpumask_add_table);

/*
 * Works only for OPP v2 bindings.
 *
 * Returns -ENOENT if operating-points-v2 bindings aren't supported.
 */
/**
 * dev_pm_opp_of_get_sharing_cpus() - Get cpumask of CPUs sharing OPPs with
 *				      @cpu_dev using operating-points-v2
 *				      bindings.
 *
 * @cpu_dev:	CPU device for which we do this operation
 * @cpumask:	cpumask to update with information of sharing CPUs
 *
 * This updates the @cpumask with CPUs that are sharing OPPs with @cpu_dev.
 *
 * Returns -ENOENT if operating-points-v2 isn't present for @cpu_dev.
 *
 * Locking: The internal opp_table and opp structures are RCU protected.
 * Hence this function internally uses RCU updater strategy with mutex locks
 * to keep the integrity of the internal data structures. Callers should ensure
 * that this function is *NOT* called under RCU protection or in contexts where
 * mutex cannot be locked.
 */
int dev_pm_opp_of_get_sharing_cpus(struct device *cpu_dev,
				   struct cpumask *cpumask)
{
	struct device_node *np, *tmp_np;
	struct device *tcpu_dev;
	int cpu, ret = 0;

	/* Get OPP descriptor node */
	np = _of_get_opp_desc_node(cpu_dev);
	if (!np) {
		dev_dbg(cpu_dev, "%s: Couldn't find cpu_dev node.\n", __func__);
		return -ENOENT;
	}

	cpumask_set_cpu(cpu_dev->id, cpumask);

	/* OPPs are shared ? */
	if (!of_property_read_bool(np, "opp-shared"))
		goto put_cpu_node;

	for_each_possible_cpu(cpu) {
		if (cpu == cpu_dev->id)
			continue;

		tcpu_dev = get_cpu_device(cpu);
		if (!tcpu_dev) {
			dev_err(cpu_dev, "%s: failed to get cpu%d device\n",
				__func__, cpu);
			ret = -ENODEV;
			goto put_cpu_node;
		}

		/* Get OPP descriptor node */
		tmp_np = _of_get_opp_desc_node(tcpu_dev);
		if (!tmp_np) {
			dev_err(tcpu_dev, "%s: Couldn't find tcpu_dev node.\n",
				__func__);
			ret = -ENOENT;
			goto put_cpu_node;
		}

		/* CPUs are sharing opp node */
		if (np == tmp_np)
			cpumask_set_cpu(cpu, cpumask);

		of_node_put(tmp_np);
	}

put_cpu_node:
	of_node_put(np);
	return ret;
}
EXPORT_SYMBOL_GPL(dev_pm_opp_of_get_sharing_cpus);