Merge remote-tracking branch 's5p/for-next'

[linux-2.6/next.git] / arch / arm / plat-omap / omap_device.c

/*
 * 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/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 <plat/omap_device.h>
#include <plat/omap_hwmod.h>
#include <plat/clock.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);

                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;
                                pr_warning("omap_device: %s.%d: new worst case "
                                           "activate latency %d: %llu\n",
                                           od->pdev.name, od->pdev.id,
                                           od->pm_lat_level, act_lat);
                        } else
                                pr_warning("omap_device: %s.%d: activate "
                                           "latency %d higher than exptected. "
                                           "(%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);

                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;
                                pr_warning("omap_device: %s.%d: new worst case "
                                           "deactivate latency %d: %llu\n",
                                           od->pdev.name, od->pdev.id,
                                           od->pm_lat_level, deact_lat);
                        } else
                                pr_warning("omap_device: %s.%d: deactivate "
                                           "latency %d higher than exptected. "
                                           "(%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 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;

        pr_debug("omap_device: %s: Creating %s -> %s\n",
                 dev_name(&od->pdev.dev), clk_alias, clk_name);

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

        r = omap_clk_get_by_name(clk_name);
        if (IS_ERR(r)) {
                pr_err("omap_device: %s: omap_clk_get_by_name for %s failed\n",
                       dev_name(&od->pdev.dev), clk_name);
                return;
        }

        l = clkdev_alloc(r, clk_alias, dev_name(&od->pdev.dev));
        if (!l) {
                pr_err("omap_device: %s: clkdev_alloc for %s failed\n",
                       dev_name(&od->pdev.dev), 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.
 */
static void _add_hwmod_clocks_clkdev(struct omap_device *od,
                                     struct omap_hwmod *oh)
{
        int i;

        _add_clkdev(od, "fck", oh->main_clk);

        for (i = 0; i < oh->opt_clks_cnt; i++)
                _add_clkdev(od, oh->opt_clks[i].role, oh->opt_clks[i].clk);
}


/* Public functions for use by core code */

/**
 * omap_device_get_context_loss_count - get lost context count
 * @od: struct omap_device *
 *
 * Using the primary hwmod, query the context loss count for this
 * device.
 *
 * Callers should consider context for this device lost any time this
 * function returns a value different than the value the caller got
 * the last time it called this function.
 *
 * If any hwmods exist for the omap_device assoiated with @pdev,
 * return the context loss counter for that hwmod, otherwise return
 * zero.
 */
u32 omap_device_get_context_loss_count(struct platform_device *pdev)
{
        struct omap_device *od;
        u32 ret = 0;

        od = to_omap_device(pdev);

        if (od->hwmods_cnt)
                ret = omap_hwmod_get_context_loss_count(od->hwmods[0]);

        return ret;
}

/**
 * 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)
{
        int c = 0;
        int i;

        for (i = 0; i < od->hwmods_cnt; i++)
                c += omap_hwmod_count_resources(od->hwmods[i]);

        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)
{
        int c = 0;
        int i, r;

        for (i = 0; i < od->hwmods_cnt; i++) {
                r = omap_hwmod_fill_resources(od->hwmods[i], 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
 * @is_early_device: should the device be registered as an early device or not
 *
 * 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, int is_early_device)
{
        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,
                                    is_early_device);
}

/**
 * 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
 * @is_early_device: should the device be registered as an early device or not
 *
 * 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 is_early_device)
{
        int ret = -ENOMEM;
        struct omap_device *od;
        char *pdev_name2;
        struct resource *res = NULL;
        int i, 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;

        ret = platform_device_add_data(&od->pdev, pdata, pdata_len);
        if (ret)
                goto odbs_exit4;

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

        if (is_early_device)
                ret = omap_early_device_register(od);
        else
                ret = omap_device_register(od);

        for (i = 0; i < oh_cnt; i++) {
                hwmods[i]->od = od;
                _add_hwmod_clocks_clkdev(od, hwmods[i]);
        }

        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_early_device_register - register an omap_device as an early platform
 * device.
 * @od: struct omap_device * to register
 *
 * Register the omap_device structure.  This currently just calls
 * platform_early_add_device() on the underlying platform_device.
 * Returns 0 by default.
 */
int omap_early_device_register(struct omap_device *od)
{
        struct platform_device *devices[1];

        devices[0] = &(od->pdev);
        early_platform_add_devices(devices, 1);
        return 0;
}

#ifdef CONFIG_PM_RUNTIME
static int _od_runtime_suspend(struct device *dev)
{
        struct platform_device *pdev = to_platform_device(dev);
        int ret;

        ret = pm_generic_runtime_suspend(dev);

        if (!ret)
                omap_device_idle(pdev);

        return ret;
}

static int _od_runtime_idle(struct device *dev)
{
        return pm_generic_runtime_idle(dev);
}

static int _od_runtime_resume(struct device *dev)
{
        struct platform_device *pdev = to_platform_device(dev);

        omap_device_enable(pdev);

        return pm_generic_runtime_resume(dev);
}
#endif

#ifdef CONFIG_SUSPEND
static int _od_suspend_noirq(struct device *dev)
{
        struct platform_device *pdev = to_platform_device(dev);
        struct omap_device *od = to_omap_device(pdev);
        int ret;

        if (od->flags & OMAP_DEVICE_NO_IDLE_ON_SUSPEND)
                return pm_generic_suspend_noirq(dev);

        ret = pm_generic_suspend_noirq(dev);

        if (!ret && !pm_runtime_status_suspended(dev)) {
                if (pm_generic_runtime_suspend(dev) == 0) {
                        omap_device_idle(pdev);
                        od->flags |= OMAP_DEVICE_SUSPENDED;
                }
        }

        return ret;
}

static int _od_resume_noirq(struct device *dev)
{
        struct platform_device *pdev = to_platform_device(dev);
        struct omap_device *od = to_omap_device(pdev);

        if (od->flags & OMAP_DEVICE_NO_IDLE_ON_SUSPEND)
                return pm_generic_resume_noirq(dev);

        if ((od->flags & OMAP_DEVICE_SUSPENDED) &&
            !pm_runtime_status_suspended(dev)) {
                od->flags &= ~OMAP_DEVICE_SUSPENDED;
                omap_device_enable(pdev);
                pm_generic_runtime_resume(dev);
        }

        return pm_generic_resume_noirq(dev);
}
#endif

static struct dev_pm_domain omap_device_pm_domain = {
        .ops = {
                SET_RUNTIME_PM_OPS(_od_runtime_suspend, _od_runtime_resume,
                                   _od_runtime_idle)
                USE_PLATFORM_PM_SLEEP_OPS
                SET_SYSTEM_SLEEP_PM_OPS(_od_suspend_noirq, _od_resume_noirq)
        }
};

/**
 * 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);

        od->pdev.dev.parent = &omap_device_parent;
        od->pdev.dev.pm_domain = &omap_device_pm_domain;
        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 = to_omap_device(pdev);

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

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

        od = to_omap_device(pdev);

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

        ret = _omap_device_deactivate(od, IGNORE_WAKEUP_LAT);

        for (i = 0; i < od->hwmods_cnt; i++)
                omap_hwmod_shutdown(od->hwmods[i]);

        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 = to_omap_device(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]);
}

/**
 * omap_device_get_mpu_rt_va - return the MPU's virtual addr for the hwmod base
 * @od: struct omap_device *
 *
 * Return the MPU's virtual address for the base of the hwmod, from
 * the ioremap() that the hwmod code does.  Only valid if there is one
 * hwmod associated with this device.  Returns NULL if there are zero
 * or more than one hwmods associated with this omap_device;
 * otherwise, passes along the return value from
 * omap_hwmod_get_mpu_rt_va().
 */
void __iomem *omap_device_get_rt_va(struct omap_device *od)
{
        if (od->hwmods_cnt != 1)
                return NULL;

        return omap_hwmod_get_mpu_rt_va(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)
{
        int i;

        for (i = 0; i < od->hwmods_cnt; i++)
                omap_hwmod_enable(od->hwmods[i]);

        /* 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)
{
        int i;

        for (i = 0; i < od->hwmods_cnt; i++)
                omap_hwmod_idle(od->hwmods[i]);

        /* 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)
{
        int i;

        for (i = 0; i < od->hwmods_cnt; i++)
                omap_hwmod_disable_clocks(od->hwmods[i]);

        /* 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)
{
        int i;

        for (i = 0; i < od->hwmods_cnt; i++)
                omap_hwmod_enable_clocks(od->hwmods[i]);

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

struct device omap_device_parent = {
        .init_name      = "omap",
        .parent         = &platform_bus,
};

static int __init omap_device_init(void)
{
        return device_register(&omap_device_parent);
}
core_initcall(omap_device_init);