/*
 * omap_device implementation
 *
 * Copyright (C) 2009 Nokia Corporation
 * Paul Walmsley
 *
 * Developed in collaboration with (alphabetical order): Benoit
 * Cousson, Kevin Hilman, 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/platform_device.h>
#include <linux/err.h>
#include <linux/io.h>

#include <plat/omap_device.h>
#include <plat/omap_hwmod.h>

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


/* 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;

	pr_debug("omap_device: %s: activating\n", od->pdev.name);

	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);

		pr_debug("omap_device: %s: pm_lat %d: activate: elapsed time "
			 "%llu nsec\n", od->pdev.name, od->pm_lat_level,
			 act_lat);

		WARN(act_lat > odpl->activate_lat, "omap_device: %s.%d: "
		     "activate step %d took longer than expected (%llu > %d)\n",
		     od->pdev.name, od->pdev.id, 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;

	pr_debug("omap_device: %s: deactivating\n", od->pdev.name);

	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);

		pr_debug("omap_device: %s: pm_lat %d: deactivate: elapsed time "
			 "%llu nsec\n", od->pdev.name, od->pm_lat_level,
			 deact_lat);

		WARN(deact_lat > odpl->deactivate_lat, "omap_device: %s.%d: "
		     "deactivate step %d took longer than expected "
		     "(%llu > %d)\n", od->pdev.name, od->pdev.id,
		     od->pm_lat_level, deact_lat, odpl->deactivate_lat);

		od->dev_wakeup_lat += odpl->activate_lat;

		od->pm_lat_level++;
	}

	return 0;
}

static inline struct omap_device *_find_by_pdev(struct platform_device *pdev)
{
	return container_of(pdev, struct omap_device, pdev);
}


/* Public functions for use by core code */

/**
 * omap_device_count_resources - count number of struct resource entries needed
 * @od: struct omap_device *
 *
 * Count the number of struct resource entries needed for this
 * omap_device @od.  Used by omap_device_build_ss() to determine how
 * much memory to allocate before calling
 * omap_device_fill_resources().  Returns the count.
 */
int omap_device_count_resources(struct omap_device *od)
{
	struct omap_hwmod *oh;
	int c = 0;
	int i;

	for (i = 0, oh = *od->hwmods; i < od->hwmods_cnt; i++, oh++)
		c += omap_hwmod_count_resources(oh);

	pr_debug("omap_device: %s: counted %d total resources across %d "
		 "hwmods\n", od->pdev.name, c, od->hwmods_cnt);

	return c;
}

/**
 * omap_device_fill_resources - fill in array of struct resource
 * @od: struct omap_device *
 * @res: pointer to an array of struct resource to be filled in
 *
 * Populate one or more empty struct resource pointed to by @res with
 * the resource data for this omap_device @od.  Used by
 * omap_device_build_ss() after calling omap_device_count_resources().
 * Ideally this function would not be needed at all.  If omap_device
 * replaces platform_device, then we can specify our own
 * get_resource()/ get_irq()/etc functions that use the underlying
 * omap_hwmod information.  Or if platform_device is extended to use
 * subarchitecture-specific function pointers, the various
 * platform_device functions can simply call omap_device internal
 * functions to get device resources.  Hacking around the existing
 * platform_device code wastes memory.  Returns 0.
 */
int omap_device_fill_resources(struct omap_device *od, struct resource *res)
{
	struct omap_hwmod *oh;
	int c = 0;
	int i, r;

	for (i = 0, oh = *od->hwmods; i < od->hwmods_cnt; i++, oh++) {
		r = omap_hwmod_fill_resources(oh, res);
		res += r;
		c += r;
	}

	return 0;
}

/**
 * omap_device_build - build and register an omap_device with one omap_hwmod
 * @pdev_name: name of the platform_device driver to use
 * @pdev_id: this platform_device's connection ID
 * @oh: ptr to the single omap_hwmod that backs this omap_device
 * @pdata: platform_data ptr to associate with the platform_device
 * @pdata_len: amount of memory pointed to by @pdata
 * @pm_lats: pointer to a omap_device_pm_latency array for this device
 * @pm_lats_cnt: ARRAY_SIZE() of @pm_lats
 *
 * Convenience function for building and registering a single
 * omap_device record, which in turn builds and registers a
 * platform_device record.  See omap_device_build_ss() for more
 * information.  Returns ERR_PTR(-EINVAL) if @oh is NULL; otherwise,
 * passes along the return value of omap_device_build_ss().
 */
struct omap_device *omap_device_build(const char *pdev_name, int pdev_id,
				      struct omap_hwmod *oh, void *pdata,
				      int pdata_len,
				      struct omap_device_pm_latency *pm_lats,
				      int pm_lats_cnt)
{
	struct omap_hwmod *ohs[] = { oh };

	if (!oh)
		return ERR_PTR(-EINVAL);

	return omap_device_build_ss(pdev_name, pdev_id, ohs, 1, pdata,
				    pdata_len, pm_lats, pm_lats_cnt);
}

/**
 * omap_device_build_ss - build and register an omap_device with multiple hwmods
 * @pdev_name: name of the platform_device driver to use
 * @pdev_id: this platform_device's connection ID
 * @oh: ptr to the single omap_hwmod that backs this omap_device
 * @pdata: platform_data ptr to associate with the platform_device
 * @pdata_len: amount of memory pointed to by @pdata
 * @pm_lats: pointer to a omap_device_pm_latency array for this device
 * @pm_lats_cnt: ARRAY_SIZE() of @pm_lats
 *
 * Convenience function for building and registering an omap_device
 * subsystem record.  Subsystem records consist of multiple
 * omap_hwmods.  This function in turn builds and registers a
 * platform_device record.  Returns an ERR_PTR() on error, or passes
 * along the return value of omap_device_register().
 */
struct omap_device *omap_device_build_ss(const char *pdev_name, int pdev_id,
					 struct omap_hwmod **ohs, int oh_cnt,
					 void *pdata, int pdata_len,
					 struct omap_device_pm_latency *pm_lats,
					 int pm_lats_cnt)
{
	int ret = -ENOMEM;
	struct omap_device *od;
	char *pdev_name2;
	struct resource *res = NULL;
	int res_count;
	struct omap_hwmod **hwmods;

	if (!ohs || oh_cnt == 0 || !pdev_name)
		return ERR_PTR(-EINVAL);

	if (!pdata && pdata_len > 0)
		return ERR_PTR(-EINVAL);

	pr_debug("omap_device: %s: building with %d hwmods\n", pdev_name,
		 oh_cnt);

	od = kzalloc(sizeof(struct omap_device), GFP_KERNEL);
	if (!od)
		return ERR_PTR(-ENOMEM);

	od->hwmods_cnt = oh_cnt;

	hwmods = kzalloc(sizeof(struct omap_hwmod *) * oh_cnt,
			 GFP_KERNEL);
	if (!hwmods)
		goto odbs_exit1;

	memcpy(hwmods, ohs, sizeof(struct omap_hwmod *) * oh_cnt);
	od->hwmods = hwmods;

	pdev_name2 = kzalloc(strlen(pdev_name) + 1, GFP_KERNEL);
	if (!pdev_name2)
		goto odbs_exit2;
	strcpy(pdev_name2, pdev_name);

	od->pdev.name = pdev_name2;
	od->pdev.id = pdev_id;

	res_count = omap_device_count_resources(od);
	if (res_count > 0) {
		res = kzalloc(sizeof(struct resource) * res_count, GFP_KERNEL);
		if (!res)
			goto odbs_exit3;
	}
	omap_device_fill_resources(od, res);

	od->pdev.num_resources = res_count;
	od->pdev.resource = res;

	platform_device_add_data(&od->pdev, pdata, pdata_len);

	od->pm_lats = pm_lats;
	od->pm_lats_cnt = pm_lats_cnt;

	ret = omap_device_register(od);
	if (ret)
		goto odbs_exit4;

	return od;

odbs_exit4:
	kfree(res);
odbs_exit3:
	kfree(pdev_name2);
odbs_exit2:
	kfree(hwmods);
odbs_exit1:
	kfree(od);

	pr_err("omap_device: %s: build failed (%d)\n", pdev_name, ret);

	return ERR_PTR(ret);
}

/**
 * omap_device_register - register an omap_device with one omap_hwmod
 * @od: struct omap_device * to register
 *
 * Register the omap_device structure.  This currently just calls
 * platform_device_register() on the underlying platform_device.
 * Returns the return value of platform_device_register().
 */
int omap_device_register(struct omap_device *od)
{
	pr_debug("omap_device: %s: registering\n", od->pdev.name);

	return platform_device_register(&od->pdev);
}


/* Public functions for use by device drivers through struct platform_data */

/**
 * omap_device_enable - fully activate an omap_device
 * @od: struct omap_device * to activate
 *
 * Do whatever is necessary for the hwmods underlying omap_device @od
 * to be accessible and ready to operate.  This generally involves
 * enabling clocks, setting SYSCONFIG registers; and in the future may
 * involve remuxing pins.  Device drivers should call this function
 * (through platform_data function pointers) where they would normally
 * enable clocks, etc.  Returns -EINVAL if called when the omap_device
 * is already enabled, or passes along the return value of
 * _omap_device_activate().
 */
int omap_device_enable(struct platform_device *pdev)
{
	int ret;
	struct omap_device *od;

	od = _find_by_pdev(pdev);

	if (od->_state == OMAP_DEVICE_STATE_ENABLED) {
		WARN(1, "omap_device: %s.%d: omap_device_enable() called from "
		     "invalid state\n", od->pdev.name, od->pdev.id);
		return -EINVAL;
	}

	/* Enable everything if we're enabling this device from scratch */
	if (od->_state == OMAP_DEVICE_STATE_UNKNOWN)
		od->pm_lat_level = od->pm_lats_cnt;

	ret = _omap_device_activate(od, IGNORE_WAKEUP_LAT);

	od->dev_wakeup_lat = 0;
	od->_dev_wakeup_lat_limit = UINT_MAX;
	od->_state = OMAP_DEVICE_STATE_ENABLED;

	return ret;
}

/**
 * omap_device_idle - idle an omap_device
 * @od: struct omap_device * to idle
 *
 * Idle omap_device @od by calling as many .deactivate_func() entries
 * in the omap_device's pm_lats table as is possible without exceeding
 * the device's maximum wakeup latency limit, pm_lat_limit.  Device
 * drivers should call this function (through platform_data function
 * pointers) where they would normally disable clocks after operations
 * complete, etc..  Returns -EINVAL if the omap_device is not
 * currently enabled, or passes along the return value of
 * _omap_device_deactivate().
 */
int omap_device_idle(struct platform_device *pdev)
{
	int ret;
	struct omap_device *od;

	od = _find_by_pdev(pdev);

	if (od->_state != OMAP_DEVICE_STATE_ENABLED) {
		WARN(1, "omap_device: %s.%d: omap_device_idle() called from "
		     "invalid state\n", od->pdev.name, od->pdev.id);
		return -EINVAL;
	}

	ret = _omap_device_deactivate(od, USE_WAKEUP_LAT);

	od->_state = OMAP_DEVICE_STATE_IDLE;

	return ret;
}

/**
 * omap_device_shutdown - shut down an omap_device
 * @od: struct omap_device * to shut down
 *
 * Shut down omap_device @od by calling all .deactivate_func() entries
 * in the omap_device's pm_lats table and then shutting down all of
 * the underlying omap_hwmods.  Used when a device is being "removed"
 * or a device driver is being unloaded.  Returns -EINVAL if the
 * omap_device is not currently enabled or idle, or passes along the
 * return value of _omap_device_deactivate().
 */
int omap_device_shutdown(struct platform_device *pdev)
{
	int ret, i;
	struct omap_device *od;
	struct omap_hwmod *oh;

	od = _find_by_pdev(pdev);

	if (od->_state != OMAP_DEVICE_STATE_ENABLED &&
	    od->_state != OMAP_DEVICE_STATE_IDLE) {
		WARN(1, "omap_device: %s.%d: omap_device_shutdown() called "
		     "from invalid state\n", od->pdev.name, od->pdev.id);
		return -EINVAL;
	}

	ret = _omap_device_deactivate(od, IGNORE_WAKEUP_LAT);

	for (i = 0, oh = *od->hwmods; i < od->hwmods_cnt; i++, oh++)
		omap_hwmod_shutdown(oh);

	od->_state = OMAP_DEVICE_STATE_SHUTDOWN;

	return ret;
}

/**
 * omap_device_align_pm_lat - activate/deactivate device to match wakeup lat lim
 * @od: struct omap_device *
 *
 * When a device's maximum wakeup latency limit changes, call some of
 * the .activate_func or .deactivate_func function pointers in the
 * omap_device's pm_lats array to ensure that the device's maximum
 * wakeup latency is less than or equal to the new latency limit.
 * Intended to be called by OMAP PM code whenever a device's maximum
 * wakeup latency limit changes (e.g., via
 * omap_pm_set_dev_wakeup_lat()).  Returns 0 if nothing needs to be
 * done (e.g., if the omap_device is not currently idle, or if the
 * wakeup latency is already current with the new limit) or passes
 * along the return value of _omap_device_deactivate() or
 * _omap_device_activate().
 */
int omap_device_align_pm_lat(struct platform_device *pdev,
			     u32 new_wakeup_lat_limit)
{
	int ret = -EINVAL;
	struct omap_device *od;

	od = _find_by_pdev(pdev);

	if (new_wakeup_lat_limit == od->dev_wakeup_lat)
		return 0;

	od->_dev_wakeup_lat_limit = new_wakeup_lat_limit;

	if (od->_state != OMAP_DEVICE_STATE_IDLE)
		return 0;
	else if (new_wakeup_lat_limit > od->dev_wakeup_lat)
		ret = _omap_device_deactivate(od, USE_WAKEUP_LAT);
	else if (new_wakeup_lat_limit < od->dev_wakeup_lat)
		ret = _omap_device_activate(od, USE_WAKEUP_LAT);

	return ret;
}

/**
 * omap_device_get_pwrdm - return the powerdomain * associated with @od
 * @od: struct omap_device *
 *
 * Return the powerdomain associated with the first underlying
 * omap_hwmod for this omap_device.  Intended for use by core OMAP PM
 * code.  Returns NULL on error or a struct powerdomain * upon
 * success.
 */
struct powerdomain *omap_device_get_pwrdm(struct omap_device *od)
{
	/*
	 * XXX Assumes that all omap_hwmod powerdomains are identical.
	 * This may not necessarily be true.  There should be a sanity
	 * check in here to WARN() if any difference appears.
	 */
	if (!od->hwmods_cnt)
		return NULL;

	return omap_hwmod_get_pwrdm(od->hwmods[0]);
}

/*
 * Public functions intended for use in omap_device_pm_latency
 * .activate_func and .deactivate_func function pointers
 */

/**
 * omap_device_enable_hwmods - call omap_hwmod_enable() on all hwmods
 * @od: struct omap_device *od
 *
 * Enable all underlying hwmods.  Returns 0.
 */
int omap_device_enable_hwmods(struct omap_device *od)
{
	struct omap_hwmod *oh;
	int i;

	for (i = 0, oh = *od->hwmods; i < od->hwmods_cnt; i++, oh++)
		omap_hwmod_enable(oh);

	/* XXX pass along return value here? */
	return 0;
}

/**
 * omap_device_idle_hwmods - call omap_hwmod_idle() on all hwmods
 * @od: struct omap_device *od
 *
 * Idle all underlying hwmods.  Returns 0.
 */
int omap_device_idle_hwmods(struct omap_device *od)
{
	struct omap_hwmod *oh;
	int i;

	for (i = 0, oh = *od->hwmods; i < od->hwmods_cnt; i++, oh++)
		omap_hwmod_idle(oh);

	/* XXX pass along return value here? */
	return 0;
}

/**
 * omap_device_disable_clocks - disable all main and interface clocks
 * @od: struct omap_device *od
 *
 * Disable the main functional clock and interface clock for all of the
 * omap_hwmods associated with the omap_device.  Returns 0.
 */
int omap_device_disable_clocks(struct omap_device *od)
{
	struct omap_hwmod *oh;
	int i;

	for (i = 0, oh = *od->hwmods; i < od->hwmods_cnt; i++, oh++)
		omap_hwmod_disable_clocks(oh);

	/* XXX pass along return value here? */
	return 0;
}

/**
 * omap_device_enable_clocks - enable all main and interface clocks
 * @od: struct omap_device *od
 *
 * Enable the main functional clock and interface clock for all of the
 * omap_hwmods associated with the omap_device.  Returns 0.
 */
int omap_device_enable_clocks(struct omap_device *od)
{
	struct omap_hwmod *oh;
	int i;

	for (i = 0, oh = *od->hwmods; i < od->hwmods_cnt; i++, oh++)
		omap_hwmod_enable_clocks(oh);

	/* XXX pass along return value here? */
	return 0;
}