/*
 * omap_device implementation
 *
 * Copyright (C) 2009-2010 Nokia Corporation
 * Paul Walmsley, Kevin Hilman
 *
 * Developed in collaboration with (alphabetical order): Benoit
 * Cousson, Thara Gopinath, Tony Lindgren, Rajendra Nayak, Vikram
 * Pandita, Sakari Poussa, Anand Sawant, Santosh Shilimkar, Richard
 * Woodruff
 *
 * 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 code provides a consistent interface for OMAP device drivers
 * to control power management and interconnect properties of their
 * devices.
 *
 * In the medium- to long-term, this code should either be
 * a) implemented via arch-specific pointers in platform_data
 * or
 * b) implemented as a proper omap_bus/omap_device in Linux, no more
 *    platform_data func pointers
 *
 *
 * Guidelines for usage by driver authors:
 *
 * 1. These functions are intended to be used by device drivers via
 * function pointers in struct platform_data.  As an example,
 * omap_device_enable() should be passed to the driver as
 *
 * struct foo_driver_platform_data {
 * ...
 *      int (*device_enable)(struct platform_device *pdev);
 * ...
 * }
 *
 * Note that the generic "device_enable" name is used, rather than
 * "omap_device_enable".  This is so other architectures can pass in their
 * own enable/disable functions here.
 *
 * This should be populated during device setup:
 *
 * ...
 * pdata->device_enable = omap_device_enable;
 * ...
 *
 * 2. Drivers should first check to ensure the function pointer is not null
 * before calling it, as in:
 *
 * if (pdata->device_enable)
 *     pdata->device_enable(pdev);
 *
 * This allows other architectures that don't use similar device_enable()/
 * device_shutdown() functions to execute normally.
 *
 * ...
 *
 * Suggested usage by device drivers:
 *
 * During device initialization:
 * device_enable()
 *
 * During device idle:
 * (save remaining device context if necessary)
 * device_idle();
 *
 * During device resume:
 * device_enable();
 * (restore context if necessary)
 *
 * During device shutdown:
 * device_shutdown()
 * (device must be reinitialized at this point to use it again)
 *
 */
#undef DEBUG

#include <linux/kernel.h>
#include <linux/export.h>
#include <linux/platform_device.h>
#include <linux/slab.h>
#include <linux/err.h>
#include <linux/io.h>
#include <linux/clk.h>
#include <linux/clkdev.h>
#include <linux/pm_runtime.h>
#include <linux/of.h>
#include <linux/notifier.h>

#include "omap_device.h"
#include "omap_hwmod.h"

/* These parameters are passed to _omap_device_{de,}activate() */
#define USE_WAKEUP_LAT			0
#define IGNORE_WAKEUP_LAT		1

static int omap_early_device_register(struct platform_device *pdev);

static struct omap_device_pm_latency omap_default_latency[] = {
	{
		.deactivate_func = omap_device_idle_hwmods,
		.activate_func   = omap_device_enable_hwmods,
		.flags = OMAP_DEVICE_LATENCY_AUTO_ADJUST,
	}
};

/* Private functions */

/**
 * _omap_device_activate - increase device readiness
 * @od: struct omap_device *
 * @ignore_lat: increase to latency target (0) or full readiness (1)?
 *
 * Increase readiness of omap_device @od (thus decreasing device
 * wakeup latency, but consuming more power).  If @ignore_lat is
 * IGNORE_WAKEUP_LAT, make the omap_device fully active.  Otherwise,
 * if @ignore_lat is USE_WAKEUP_LAT, and the device's maximum wakeup
 * latency is greater than the requested maximum wakeup latency, step
 * backwards in the omap_device_pm_latency table to ensure the
 * device's maximum wakeup latency is less than or equal to the
 * requested maximum wakeup latency.  Returns 0.
 */
static int _omap_device_activate(struct omap_device *od, u8 ignore_lat)
{
	struct timespec a, b, c;

	dev_dbg(&od->pdev->dev, "omap_device: activating\n");

	while (od->pm_lat_level > 0) {
		struct omap_device_pm_latency *odpl;
		unsigned long long act_lat = 0;

		od->pm_lat_level--;

		odpl = od->pm_lats + od->pm_lat_level;

		if (!ignore_lat &&
		    (od->dev_wakeup_lat <= od->_dev_wakeup_lat_limit))
			break;

		read_persistent_clock(&a);

		/* XXX check return code */
		odpl->activate_func(od);

		read_persistent_clock(&b);

		c = timespec_sub(b, a);
		act_lat = timespec_to_ns(&c);

		dev_dbg(&od->pdev->dev,
			"omap_device: pm_lat %d: activate: elapsed time %llu nsec\n",
			od->pm_lat_level, act_lat);

		if (act_lat > odpl->activate_lat) {
			odpl->activate_lat_worst = act_lat;
			if (odpl->flags & OMAP_DEVICE_LATENCY_AUTO_ADJUST) {
				odpl->activate_lat = act_lat;
				dev_dbg(&od->pdev->dev,
					"new worst case activate latency %d: %llu\n",
					od->pm_lat_level, act_lat);
			} else
				dev_warn(&od->pdev->dev,
					 "activate latency %d higher than expected. (%llu > %d)\n",
					 od->pm_lat_level, act_lat,
					 odpl->activate_lat);
		}

		od->dev_wakeup_lat -= odpl->activate_lat;
	}

	return 0;
}

/**
 * _omap_device_deactivate - decrease device readiness
 * @od: struct omap_device *
 * @ignore_lat: decrease to latency target (0) or full inactivity (1)?
 *
 * Decrease readiness of omap_device @od (thus increasing device
 * wakeup latency, but conserving power).  If @ignore_lat is
 * IGNORE_WAKEUP_LAT, make the omap_device fully inactive.  Otherwise,
 * if @ignore_lat is USE_WAKEUP_LAT, and the device's maximum wakeup
 * latency is less than the requested maximum wakeup latency, step
 * forwards in the omap_device_pm_latency table to ensure the device's
 * maximum wakeup latency is less than or equal to the requested
 * maximum wakeup latency.  Returns 0.
 */
static int _omap_device_deactivate(struct omap_device *od, u8 ignore_lat)
{
	struct timespec a, b, c;

	dev_dbg(&od->pdev->dev, "omap_device: deactivating\n");

	while (od->pm_lat_level < od->pm_lats_cnt) {
		struct omap_device_pm_latency *odpl;
		unsigned long long deact_lat = 0;

		odpl = od->pm_lats + od->pm_lat_level;

		if (!ignore_lat &&
		    ((od->dev_wakeup_lat + odpl->activate_lat) >
		     od->_dev_wakeup_lat_limit))
			break;

		read_persistent_clock(&a);

		/* XXX check return code */
		odpl->deactivate_func(od);

		read_persistent_clock(&b);

		c = timespec_sub(b, a);
		deact_lat = timespec_to_ns(&c);

		dev_dbg(&od->pdev->dev,
			"omap_device: pm_lat %d: deactivate: elapsed time %llu nsec\n",
			od->pm_lat_level, deact_lat);

		if (deact_lat > odpl->deactivate_lat) {
			odpl->deactivate_lat_worst = deact_lat;
			if (odpl->flags & OMAP_DEVICE_LATENCY_AUTO_ADJUST) {
				odpl->deactivate_lat = deact_lat;
				dev_dbg(&od->pdev->dev,
					"new worst case deactivate latency %d: %llu\n",
					od->pm_lat_level, deact_lat);
			} else
				dev_warn(&od->pdev->dev,
					 "deactivate latency %d higher than expected. (%llu > %d)\n",
					 od->pm_lat_level, deact_lat,
					 odpl->deactivate_lat);
		}

		od->dev_wakeup_lat += odpl->activate_lat;

		od->pm_lat_level++;
	}

	return 0;
}

static void _add_clkdev(struct omap_device *od, const char *clk_alias,
		       const char *clk_name)
{
	struct clk *r;
	struct clk_lookup *l;

	if (!clk_alias || !clk_name)
		return;

	dev_dbg(&od->pdev->dev, "Creating %s -> %s\n", clk_alias, clk_name);

	r = clk_get_sys(dev_name(&od->pdev->dev), clk_alias);
	if (!IS_ERR(r)) {
		dev_warn(&od->pdev->dev,
			 "alias %s already exists\n", clk_alias);
		clk_put(r);
		return;
	}

	r = clk_get(NULL, clk_name);
	if (IS_ERR(r)) {
		dev_err(&od->pdev->dev,
			"clk_get for %s failed\n", clk_name);
		return;
	}

	l = clkdev_alloc(r, clk_alias, dev_name(&od->pdev->dev));
	if (!l) {
		dev_err(&od->pdev->dev,
			"clkdev_alloc for %s failed\n", clk_alias);
		return;
	}

	clkdev_add(l);
}

/**
 * _add_hwmod_clocks_clkdev - Add clkdev entry for hwmod optional clocks
 * and main clock
 * @od: struct omap_device *od
 * @oh: struct omap_hwmod *oh
 *
 * For the main clock and every optional clock present per hwmod per
 * omap_device, this function adds an entry in the clkdev table of the
 * form <dev-id=dev_name, con-id=role> if it does not exist already.
 *
 * The function is called from inside omap_device_build_ss(), after
 * omap_device_register.
 *
 * This allows drivers to get a pointer to its optional clocks based on its role
 * by calling clk_get(<dev*>, <role>).
 * In the case of the main clock, a "fck" alias is used.
 *
 * No return value.
 */