OMAP2/3/4 core: create omap_device layer

The omap_device code provides a mapping of omap_hwmod structures into
the platform_device system, and includes some details on external
(board-level) integration.  This allows drivers to enable, idle, and
shutdown on-chip device resources, including clocks, regulators, etc.
The resources enabled and idled are dependent on the device's maximum
wakeup latency constraint (if present).

At the moment, omap_device functions are intended to be called from
platform_data function pointers.  Ideally in the future these
functions will be called from either subarchitecture-specific
platform_data activate, deactivate functions, or via an custom
bus/device type for OMAP.

Signed-off-by: Paul Walmsley <paul@pwsan.com>
Cc: Benoit Cousson <b-cousson@ti.com>
Cc: Kevin Hilman <khilman@deeprootsystems.com>
Cc: Tony Lindgren <tony@atomide.com>
Cc: Rajendra Nayak <rnayak@ti.com>
Cc: Vikram Pandita <vikram.pandita@ti.com>
Cc: Sakari Poussa <sakari.poussa@nokia.com>
Cc: Anand Sawant <sawant@ti.com>
Cc: Santosh Shilimkar <santosh.shilimkar@ti.com>
Cc: Eric Thomas <ethomas@ti.com>
Cc: Richard Woodruff <r-woodruff2@ti.com>

arch/arm/plat-omap/Makefile

@@ -12,6 +12,10 @@ obj-  :=
 # OCPI interconnect support for 1710, 1610 and 5912
 obj-$(CONFIG_ARCH_OMAP16XX) += ocpi.o
 
+# omap_device support (OMAP2+ only at the moment)
+obj-$(CONFIG_ARCH_OMAP2) += omap_device.o
+obj-$(CONFIG_ARCH_OMAP3) += omap_device.o
+
 obj-$(CONFIG_OMAP_MCBSP) += mcbsp.o
 obj-$(CONFIG_OMAP_IOMMU) += iommu.o iovmm.o
 obj-$(CONFIG_OMAP_IOMMU_DEBUG) += iommu-debug.o

arch/arm/plat-omap/include/mach/omap_device.h

@@ -0,0 +1,141 @@
+/*
+ * omap_device headers
+ *
+ * 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.
+ *
+ * Eventually this type of functionality should either be
+ * a) implemented via arch-specific pointers in platform_device
+ * or
+ * b) implemented as a proper omap_bus/omap_device in Linux, no more
+ *    platform_device
+ *
+ * omap_device differs from omap_hwmod in that it includes external
+ * (e.g., board- and system-level) integration details.  omap_hwmod
+ * stores hardware data that is invariant for a given OMAP chip.
+ *
+ * To do:
+ * - GPIO integration
+ * - regulator integration
+ *
+ */
+#ifndef __ARCH_ARM_PLAT_OMAP_INCLUDE_MACH_OMAP_DEVICE_H
+#define __ARCH_ARM_PLAT_OMAP_INCLUDE_MACH_OMAP_DEVICE_H
+
+#include <linux/kernel.h>
+#include <linux/platform_device.h>
+
+#include <mach/omap_hwmod.h>
+
+/* omap_device._state values */
+#define OMAP_DEVICE_STATE_UNKNOWN	0
+#define OMAP_DEVICE_STATE_ENABLED	1
+#define OMAP_DEVICE_STATE_IDLE		2
+#define OMAP_DEVICE_STATE_SHUTDOWN	3
+
+/**
+ * struct omap_device - omap_device wrapper for platform_devices
+ * @pdev: platform_device
+ * @hwmods: (one .. many per omap_device)
+ * @hwmods_cnt: ARRAY_SIZE() of @hwmods
+ * @pm_lats: ptr to an omap_device_pm_latency table
+ * @pm_lats_cnt: ARRAY_SIZE() of what is passed to @pm_lats
+ * @pm_lat_level: array index of the last odpl entry executed - -1 if never
+ * @dev_wakeup_lat: dev wakeup latency in microseconds
+ * @_dev_wakeup_lat_limit: dev wakeup latency limit in usec - set by OMAP PM
+ * @_state: one of OMAP_DEVICE_STATE_* (see above)
+ * @flags: device flags
+ *
+ * Integrates omap_hwmod data into Linux platform_device.
+ *
+ * Field names beginning with underscores are for the internal use of
+ * the omap_device code.
+ *
+ */
+struct omap_device {
+	struct platform_device		pdev;
+	struct omap_hwmod		**hwmods;
+	struct omap_device_pm_latency	*pm_lats;
+	u32				dev_wakeup_lat;
+	u32				_dev_wakeup_lat_limit;
+	u8				pm_lats_cnt;
+	s8				pm_lat_level;
+	u8				hwmods_cnt;
+	u8				_state;
+};
+
+/* Device driver interface (call via platform_data fn ptrs) */
+
+int omap_device_enable(struct platform_device *pdev);
+int omap_device_idle(struct platform_device *pdev);
+int omap_device_shutdown(struct platform_device *pdev);
+
+/* Core code interface */
+
+int omap_device_count_resources(struct omap_device *od);
+int omap_device_fill_resources(struct omap_device *od, struct resource *res);
+
+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_device *omap_device_build_ss(const char *pdev_name, int pdev_id,
+					 struct omap_hwmod **oh, int oh_cnt,
+					 void *pdata, int pdata_len,
+					 struct omap_device_pm_latency *pm_lats,
+					 int pm_lats_cnt);
+
+int omap_device_register(struct omap_device *od);
+
+/* OMAP PM interface */
+int omap_device_align_pm_lat(struct platform_device *pdev,
+			     u32 new_wakeup_lat_limit);
+struct powerdomain *omap_device_get_pwrdm(struct omap_device *od);
+
+/* Other */
+
+int omap_device_idle_hwmods(struct omap_device *od);
+int omap_device_enable_hwmods(struct omap_device *od);
+
+int omap_device_disable_clocks(struct omap_device *od);
+int omap_device_enable_clocks(struct omap_device *od);
+
+
+/*
+ * Entries should be kept in latency order ascending
+ *
+ * deact_lat is the maximum number of microseconds required to complete
+ * deactivate_func() at the device's slowest OPP.
+ *
+ * act_lat is the maximum number of microseconds required to complete
+ * activate_func() at the device's slowest OPP.
+ *
+ * This will result in some suboptimal power management decisions at fast
+ * OPPs, but avoids having to recompute all device power management decisions
+ * if the system shifts from a fast OPP to a slow OPP (in order to meet
+ * latency requirements).
+ *
+ * XXX should deactivate_func/activate_func() take platform_device pointers
+ * rather than omap_device pointers?
+ */
+struct omap_device_pm_latency {
+	u32 deactivate_lat;
+	int (*deactivate_func)(struct omap_device *od);
+	u32 activate_lat;
+	int (*activate_func)(struct omap_device *od);
+};
+
+
+#endif
+

arch/arm/plat-omap/omap_device.c

@@ -0,0 +1,687 @@
+/*
+ * 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 <mach/omap_device.h>
+#include <mach/omap_hwmod.h>
+
+/* These parameters are passed to _omap_device_{de,}activate() */
+#define USE_WAKEUP_LAT			0
+#define IGNORE_WAKEUP_LAT		1
+
+/* XXX this should be moved into a separate file */
+#if defined(CONFIG_ARCH_OMAP2420)
+# define OMAP_32KSYNCT_BASE		0x48004000
+#elif defined(CONFIG_ARCH_OMAP2430)
+# define OMAP_32KSYNCT_BASE		0x49020000
+#elif defined(CONFIG_ARCH_OMAP3430)
+# define OMAP_32KSYNCT_BASE		0x48320000
+#else
+# error Unknown OMAP device
+#endif
+
+/* Private functions */
+
+/**
+ * _read_32ksynct - read the OMAP 32K sync timer
+ *
+ * Returns the current value of the 32KiHz synchronization counter.
+ * XXX this should be generalized to simply read the system clocksource.
+ * XXX this should be moved to a separate synctimer32k.c file
+ */
+static u32 _read_32ksynct(void)
+{
+	if (!cpu_class_is_omap2())
+		BUG();
+
+	return __raw_readl(OMAP2_IO_ADDRESS(OMAP_32KSYNCT_BASE + 0x010));
+}
+
+/**
+ * _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)
+{
+	u32 a, b;
+
+	pr_debug("omap_device: %s: activating\n", od->pdev.name);
+
+	while (od->pm_lat_level > 0) {
+		struct omap_device_pm_latency *odpl;
+		int 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;
+
+		a = _read_32ksynct();
+
+		/* XXX check return code */
+		odpl->activate_func(od);
+
+		b = _read_32ksynct();
+
+		act_lat = (b - a) >> 15; /* 32KiHz cycles to microseconds */
+
+		pr_debug("omap_device: %s: pm_lat %d: activate: elapsed time "
+			 "%d usec\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 (%d > %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)
+{
+	u32 a, b;
+
+	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;
+		int 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;
+
+		a = _read_32ksynct();
+
+		/* XXX check return code */
+		odpl->deactivate_func(od);
+
+		b = _read_32ksynct();
+
+		deact_lat = (b - a) >> 15; /* 32KiHz cycles to microseconds */
+
+		pr_debug("omap_device: %s: pm_lat %d: deactivate: elapsed time "
+			 "%d usec\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 (%d > %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 = INT_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;
+}