text: /*
   * OMAP2/3/4 clockdomain framework functions
   *
   * Copyright (C) 2008-2011 Texas Instruments, Inc.
   * Copyright (C) 2008-2011 Nokia Corporation
   *
   * Written by Paul Walmsley and Jouni Högander
   * Added OMAP4 specific support by Abhijit Pagare <abhijitpagare@ti.com>
   *
   * 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.
   */
  #undef DEBUG
  
  #include <linux/kernel.h>
  #include <linux/device.h>
  #include <linux/list.h>
  #include <linux/errno.h>
  #include <linux/string.h>
  #include <linux/delay.h>
  #include <linux/clk.h>
  #include <linux/limits.h>
  #include <linux/err.h>
  #include <linux/clk-provider.h>
  
  #include <linux/io.h>
  
  #include <linux/bitops.h>
  
  #include "soc.h"
  #include "clock.h"
  #include "clockdomain.h"
  
  /* clkdm_list contains all registered struct clockdomains */
  static LIST_HEAD(clkdm_list);
  
  /* array of clockdomain deps to be added/removed when clkdm in hwsup mode */
  static struct clkdm_autodep *autodeps;
  
  static struct clkdm_ops *arch_clkdm;
  
  /* Private functions */
  
  static struct clockdomain *_clkdm_lookup(const char *name)
  {
  	struct clockdomain *clkdm, *temp_clkdm;
  
  	if (!name)
  		return NULL;
  
  	clkdm = NULL;
  
  	list_for_each_entry(temp_clkdm, &clkdm_list, node) {
  		if (!strcmp(name, temp_clkdm->name)) {
  			clkdm = temp_clkdm;
  			break;
  		}
  	}
  
  	return clkdm;
  }
  
  /**
   * _clkdm_register - register a clockdomain
   * @clkdm: struct clockdomain * to register
   *
   * Adds a clockdomain to the internal clockdomain list.
   * Returns -EINVAL if given a null pointer, -EEXIST if a clockdomain is
   * already registered by the provided name, or 0 upon success.
   */
  static int _clkdm_register(struct clockdomain *clkdm)
  {
  	struct powerdomain *pwrdm;
  
  	if (!clkdm || !clkdm->name)
  		return -EINVAL;
  
  	pwrdm = pwrdm_lookup(clkdm->pwrdm.name);
  	if (!pwrdm) {
  		pr_err("clockdomain: %s: powerdomain %s does not exist\n",
  			clkdm->name, clkdm->pwrdm.name);
  		return -EINVAL;
  	}
  	clkdm->pwrdm.ptr = pwrdm;
  
  	/* Verify that the clockdomain is not already registered */
  	if (_clkdm_lookup(clkdm->name))
  		return -EEXIST;
  
  	list_add(&clkdm->node, &clkdm_list);
  
  	pwrdm_add_clkdm(pwrdm, clkdm);
  
  	pr_debug("clockdomain: registered %s\n", clkdm->name);
  
  	return 0;
  }
  
  /* _clkdm_deps_lookup - look up the specified clockdomain in a clkdm list */
  static struct clkdm_dep *_clkdm_deps_lookup(struct clockdomain *clkdm,
  					    struct clkdm_dep *deps)
  {
  	struct clkdm_dep *cd;
  
  	if (!clkdm || !deps)
  		return ERR_PTR(-EINVAL);
  
  	for (cd = deps; cd->clkdm_name; cd++) {
  		if (!cd->clkdm && cd->clkdm_name)
  			cd->clkdm = _clkdm_lookup(cd->clkdm_name);
  
  		if (cd->clkdm == clkdm)
  			break;
  	}
  
  	if (!cd->clkdm_name)
  		return ERR_PTR(-ENOENT);
  
  	return cd;
  }
  
  /**
   * _autodep_lookup - resolve autodep clkdm names to clkdm pointers; store
   * @autodep: struct clkdm_autodep * to resolve
   *
   * Resolve autodep clockdomain names to clockdomain pointers via
   * clkdm_lookup() and store the pointers in the autodep structure.  An
   * "autodep" is a clockdomain sleep/wakeup dependency that is
   * automatically added and removed whenever clocks in the associated
   * clockdomain are enabled or disabled (respectively) when the
   * clockdomain is in hardware-supervised mode.	Meant to be called
   * once at clockdomain layer initialization, since these should remain
   * fixed for a particular architecture.  No return value.
   *
   * XXX autodeps are deprecated and should be removed at the earliest
   * opportunity
   */
  static void _autodep_lookup(struct clkdm_autodep *autodep)
  {
  	struct clockdomain *clkdm;
  
  	if (!autodep)
  		return;
  
  	clkdm = clkdm_lookup(autodep->clkdm.name);
  	if (!clkdm) {
  		pr_err("clockdomain: autodeps: clockdomain %s does not exist\n",
  			 autodep->clkdm.name);
  		clkdm = ERR_PTR(-ENOENT);
  	}
  	autodep->clkdm.ptr = clkdm;
  }
  
  /**
   * _resolve_clkdm_deps() - resolve clkdm_names in @clkdm_deps to clkdms
   * @clkdm: clockdomain that we are resolving dependencies for
   * @clkdm_deps: ptr to array of struct clkdm_deps to resolve
   *
   * Iterates through @clkdm_deps, looking up the struct clockdomain named by
   * clkdm_name and storing the clockdomain pointer in the struct clkdm_dep.
   * No return value.
   */
  static void _resolve_clkdm_deps(struct clockdomain *clkdm,
  				struct clkdm_dep *clkdm_deps)
  {
  	struct clkdm_dep *cd;
  
  	for (cd = clkdm_deps; cd && cd->clkdm_name; cd++) {
  		if (cd->clkdm)
  			continue;
  		cd->clkdm = _clkdm_lookup(cd->clkdm_name);
  
  		WARN(!cd->clkdm, "clockdomain: %s: could not find clkdm %s while resolving dependencies - should never happen",
  		     clkdm->name, cd->clkdm_name);
  	}
  }
  
  /**
   * _clkdm_add_wkdep - add a wakeup dependency from clkdm2 to clkdm1 (lockless)
   * @clkdm1: wake this struct clockdomain * up (dependent)
   * @clkdm2: when this struct clockdomain * wakes up (source)
   *
   * When the clockdomain represented by @clkdm2 wakes up, wake up
   * @clkdm1. Implemented in hardware on the OMAP, this feature is
   * designed to reduce wakeup latency of the dependent clockdomain @clkdm1.
   * Returns -EINVAL if presented with invalid clockdomain pointers,
   * -ENOENT if @clkdm2 cannot wake up clkdm1 in hardware, or 0 upon
   * success.
   */
  static int _clkdm_add_wkdep(struct clockdomain *clkdm1,
  			    struct clockdomain *clkdm2)
  {
  	struct clkdm_dep *cd;
  	int ret = 0;
  
  	if (!clkdm1 || !clkdm2)
  		return -EINVAL;
  
  	cd = _clkdm_deps_lookup(clkdm2, clkdm1->wkdep_srcs);
  	if (IS_ERR(cd))
  		ret = PTR_ERR(cd);
  
  	if (!arch_clkdm || !arch_clkdm->clkdm_add_wkdep)
  		ret = -EINVAL;
  
  	if (ret) {
  		pr_debug("clockdomain: hardware cannot set/clear wake up of %s when %s wakes up\n",
  			 clkdm1->name, clkdm2->name);
  		return ret;
  	}
  
  	cd->wkdep_usecount++;
  	if (cd->wkdep_usecount == 1) {
  		pr_debug("clockdomain: hardware will wake up %s when %s wakes up\n",
  			 clkdm1->name, clkdm2->name);
  
  		ret = arch_clkdm->clkdm_add_wkdep(clkdm1, clkdm2);
  	}
  
  	return ret;
  }
  
  /**
   * _clkdm_del_wkdep - remove a wakeup dep from clkdm2 to clkdm1 (lockless)
   * @clkdm1: wake this struct clockdomain * up (dependent)
   * @clkdm2: when this struct clockdomain * wakes up (source)
   *
   * Remove a wakeup dependency causing @clkdm1 to wake up when @clkdm2
   * wakes up.  Returns -EINVAL if presented with invalid clockdomain
   * pointers, -ENOENT if @clkdm2 cannot wake up clkdm1 in hardware, or
   * 0 upon success.
   */
  static int _clkdm_del_wkdep(struct clockdomain *clkdm1,
  			    struct clockdomain *clkdm2)
  {
  	struct clkdm_dep *cd;
  	int ret = 0;
  
  	if (!clkdm1 || !clkdm2)
  		return -EINVAL;
  
  	cd = _clkdm_deps_lookup(clkdm2, clkdm1->wkdep_srcs);
  	if (IS_ERR(cd))
  		ret = PTR_ERR(cd);
  
  	if (!arch_clkdm || !arch_clkdm->clkdm_del_wkdep)
  		ret = -EINVAL;
  
  	if (ret) {
  		pr_debug("clockdomain: hardware cannot set/clear wake up of %s when %s wakes up\n",
  			 clkdm1->name, clkdm2->name);
  		return ret;
  	}
  
  	cd->wkdep_usecount--;
  	if (cd->wkdep_usecount == 0) {
  		pr_debug("clockdomain: hardware will no longer wake up %s after %s wakes up\n",
  			 clkdm1->name, clkdm2->name);
  
  		ret = arch_clkdm->clkdm_del_wkdep(clkdm1, clkdm2);
  	}
  
  	return ret;
  }
  
  /**
   * _clkdm_add_sleepdep - add a sleep dependency from clkdm2 to clkdm1 (lockless)
   * @clkdm1: prevent this struct clockdomain * from sleeping (dependent)
   * @clkdm2: when this struct clockdomain * is active (source)
   *
   * Prevent @clkdm1 from automatically going inactive (and then to
   * retention or off) if @clkdm2 is active.  Returns -EINVAL if
   * presented with invalid clockdomain pointers or called on a machine
   * that does not support software-configurable hardware sleep
   * dependencies, -ENOENT if the specified dependency cannot be set in
   * hardware, or 0 upon success.
   */
  static int _clkdm_add_sleepdep(struct clockdomain *clkdm1,
  			       struct clockdomain *clkdm2)
  {
  	struct clkdm_dep *cd;
  	int ret = 0;
  
  	if (!clkdm1 || !clkdm2)
  		return -EINVAL;
  
  	cd = _clkdm_deps_lookup(clkdm2, clkdm1->sleepdep_srcs);
  	if (IS_ERR(cd))
  		ret = PTR_ERR(cd);
  
  	if (!arch_clkdm || !arch_clkdm->clkdm_add_sleepdep)
  		ret = -EINVAL;
  
  	if (ret) {
  		pr_debug("clockdomain: hardware cannot set/clear sleep dependency affecting %s from %s\n",
  			 clkdm1->name, clkdm2->name);
  		return ret;
  	}
  
  	cd->sleepdep_usecount++;
  	if (cd->sleepdep_usecount == 1) {
  		pr_debug("clockdomain: will prevent %s from sleeping if %s is active\n",
  			 clkdm1->name, clkdm2->name);
  
  		ret = arch_clkdm->clkdm_add_sleepdep(clkdm1, clkdm2);
  	}
  
  	return ret;
  }
  
  /**
   * _clkdm_del_sleepdep - remove a sleep dep from clkdm2 to clkdm1 (lockless)
   * @clkdm1: prevent this struct clockdomain * from sleeping (dependent)
   * @clkdm2: when this struct clockdomain * is active (source)
   *
   * Allow @clkdm1 to automatically go inactive (and then to retention or
   * off), independent of the activity state of @clkdm2.  Returns -EINVAL
   * if presented with invalid clockdomain pointers or called on a machine
   * that does not support software-configurable hardware sleep dependencies,
   * -ENOENT if the specified dependency cannot be cleared in hardware, or
   * 0 upon success.
   */
  static int _clkdm_del_sleepdep(struct clockdomain *clkdm1,
  			       struct clockdomain *clkdm2)
  {
  	struct clkdm_dep *cd;
  	int ret = 0;
  
  	if (!clkdm1 || !clkdm2)
  		return -EINVAL;
  
  	cd = _clkdm_deps_lookup(clkdm2, clkdm1->sleepdep_srcs);
  	if (IS_ERR(cd))
  		ret = PTR_ERR(cd);
  
  	if (!arch_clkdm || !arch_clkdm->clkdm_del_sleepdep)
  		ret = -EINVAL;
  
  	if (ret) {
  		pr_debug("clockdomain: hardware cannot set/clear sleep dependency affecting %s from %s\n",
  			 clkdm1->name, clkdm2->name);
  		return ret;
  	}
  
  	cd->sleepdep_usecount--;
  	if (cd->sleepdep_usecount == 0) {
  		pr_debug("clockdomain: will no longer prevent %s from sleeping if %s is active\n",
  			 clkdm1->name, clkdm2->name);
  
  		ret = arch_clkdm->clkdm_del_sleepdep(clkdm1, clkdm2);
  	}
  
  	return ret;
  }
  
  /* Public functions */
  
  /**
   * clkdm_register_platform_funcs - register clockdomain implementation fns
   * @co: func pointers for arch specific implementations
   *
   * Register the list of function pointers used to implement the
   * clockdomain functions on different OMAP SoCs.  Should be called
   * before any other clkdm_register*() function.  Returns -EINVAL if
   * @co is null, -EEXIST if platform functions have already been
   * registered, or 0 upon success.
   */
  int clkdm_register_platform_funcs(struct clkdm_ops *co)
  {
  	if (!co)
  		return -EINVAL;
  
  	if (arch_clkdm)
  		return -EEXIST;
  
  	arch_clkdm = co;
  
  	return 0;
  };
  
  /**
   * clkdm_register_clkdms - register SoC clockdomains
   * @cs: pointer to an array of struct clockdomain to register
   *
   * Register the clockdomains available on a particular OMAP SoC.  Must
   * be called after clkdm_register_platform_funcs().  May be called
   * multiple times.  Returns -EACCES if called before
   * clkdm_register_platform_funcs(); -EINVAL if the argument @cs is
   * null; or 0 upon success.
   */
  int clkdm_register_clkdms(struct clockdomain **cs)
  {
  	struct clockdomain **c = NULL;
  
  	if (!arch_clkdm)
  		return -EACCES;
  
  	if (!cs)
  		return -EINVAL;
  
  	for (c = cs; *c; c++)
  		_clkdm_register(*c);
  
  	return 0;
  }
  
  /**
   * clkdm_register_autodeps - register autodeps (if required)
   * @ia: pointer to a static array of struct clkdm_autodep to register
   *
   * Register clockdomain "automatic dependencies."  These are
   * clockdomain wakeup and sleep dependencies that are automatically
   * added whenever the first clock inside a clockdomain is enabled, and
   * removed whenever the last clock inside a clockdomain is disabled.
   * These are currently only used on OMAP3 devices, and are deprecated,
   * since they waste energy.  However, until the OMAP2/3 IP block
   * enable/disable sequence can be converted to match the OMAP4
   * sequence, they are needed.
   *
   * Must be called only after all of the SoC clockdomains are
   * registered, since the function will resolve autodep clockdomain
   * names into clockdomain pointers.
   *
   * The struct clkdm_autodep @ia array must be static, as this function
   * does not copy the array elements.
   *
   * Returns -EACCES if called before any clockdomains have been
   * registered, -EINVAL if called with a null @ia argument, -EEXIST if
   * autodeps have already been registered, or 0 upon success.
   */
  int clkdm_register_autodeps(struct clkdm_autodep *ia)
  {
  	struct clkdm_autodep *a = NULL;
  
  	if (list_empty(&clkdm_list))
  		return -EACCES;
  
  	if (!ia)
  		return -EINVAL;
  
  	if (autodeps)
  		return -EEXIST;
  
  	autodeps = ia;
  	for (a = autodeps; a->clkdm.ptr; a++)
  		_autodep_lookup(a);
  
  	return 0;
  }
  
  /**
   * clkdm_complete_init - set up the clockdomain layer
   *
   * Put all clockdomains into software-supervised mode; PM code should
   * later enable hardware-supervised mode as appropriate.  Must be
   * called after clkdm_register_clkdms().  Returns -EACCES if called
   * before clkdm_register_clkdms(), or 0 upon success.
   */
  int clkdm_complete_init(void)
  {
  	struct clockdomain *clkdm;
  
  	if (list_empty(&clkdm_list))
  		return -EACCES;
  
  	list_for_each_entry(clkdm, &clkdm_list, node) {
  		clkdm_deny_idle(clkdm);
  
  		_resolve_clkdm_deps(clkdm, clkdm->wkdep_srcs);
  		clkdm_clear_all_wkdeps(clkdm);
  
  		_resolve_clkdm_deps(clkdm, clkdm->sleepdep_srcs);
  		clkdm_clear_all_sleepdeps(clkdm);
  	}
  
  	return 0;
  }
  
  /**
   * clkdm_lookup - look up a clockdomain by name, return a pointer
   * @name: name of clockdomain
   *
   * Find a registered clockdomain by its name @name.  Returns a pointer
   * to the struct clockdomain if found, or NULL otherwise.
   */
  struct clockdomain *clkdm_lookup(const char *name)
  {
  	struct clockdomain *clkdm, *temp_clkdm;
  
  	if (!name)
  		return NULL;
  
  	clkdm = NULL;
  
  	list_for_each_entry(temp_clkdm, &clkdm_list, node) {
  		if (!strcmp(name, temp_clkdm->name)) {
  			clkdm = temp_clkdm;
  			break;
  		}
  	}
  
  	return clkdm;
  }
  
  /**
   * clkdm_for_each - call function on each registered clockdomain
   * @fn: callback function *
   *
   * Call the supplied function @fn for each registered clockdomain.
   * The callback function @fn can return anything but 0 to bail
   * out early from the iterator.  The callback function is called with
   * the clkdm_mutex held, so no clockdomain structure manipulation
   * functions should be called from the callback, although hardware
   * clockdomain control functions are fine.  Returns the last return
   * value of the callback function, which should be 0 for success or
   * anything else to indicate failure; or -EINVAL if the function pointer
   * is null.
   */
  int clkdm_for_each(int (*fn)(struct clockdomain *clkdm, void *user),
  			void *user)
  {
  	struct clockdomain *clkdm;
  	int ret = 0;
  
  	if (!fn)
  		return -EINVAL;
  
  	list_for_each_entry(clkdm, &clkdm_list, node) {
  		ret = (*fn)(clkdm, user);
  		if (ret)
  			break;
  	}
  
  	return ret;
  }
  
  
  /**
   * clkdm_get_pwrdm - return a ptr to the pwrdm that this clkdm resides in
   * @clkdm: struct clockdomain *
   *
   * Return a pointer to the struct powerdomain that the specified clockdomain
   * @clkdm exists in, or returns NULL if @clkdm is NULL.
   */
  struct powerdomain *clkdm_get_pwrdm(struct clockdomain *clkdm)
  {
  	if (!clkdm)
  		return NULL;
  
  	return clkdm->pwrdm.ptr;
  }
  
  
  /* Hardware clockdomain control */
  
  /**
   * clkdm_add_wkdep - add a wakeup dependency from clkdm2 to clkdm1
   * @clkdm1: wake this struct clockdomain * up (dependent)
   * @clkdm2: when this struct clockdomain * wakes up (source)
   *
   * When the clockdomain represented by @clkdm2 wakes up, wake up
   * @clkdm1. Implemented in hardware on the OMAP, this feature is
   * designed to reduce wakeup latency of the dependent clockdomain @clkdm1.
   * Returns -EINVAL if presented with invalid clockdomain pointers,
   * -ENOENT if @clkdm2 cannot wake up clkdm1 in hardware, or 0 upon
   * success.
   */
  int clkdm_add_wkdep(struct clockdomain *clkdm1, struct clockdomain *clkdm2)
  {
  	struct clkdm_dep *cd;
  	int ret;
  
  	if (!clkdm1 || !clkdm2)
  		return -EINVAL;
  
  	cd = _clkdm_deps_lookup(clkdm2, clkdm1->wkdep_srcs);
  	if (IS_ERR(cd))
  		return PTR_ERR(cd);
  
  	pwrdm_lock(cd->clkdm->pwrdm.ptr);
  	ret = _clkdm_add_wkdep(clkdm1, clkdm2);
  	pwrdm_unlock(cd->clkdm->pwrdm.ptr);
  
  	return ret;
  }
  
  /**
   * clkdm_del_wkdep - remove a wakeup dependency from clkdm2 to clkdm1
   * @clkdm1: wake this struct clockdomain * up (dependent)
   * @clkdm2: when this struct clockdomain * wakes up (source)
   *
   * Remove a wakeup dependency causing @clkdm1 to wake up when @clkdm2
   * wakes up.  Returns -EINVAL if presented with invalid clockdomain
   * pointers, -ENOENT if @clkdm2 cannot wake up clkdm1 in hardware, or
   * 0 upon success.
   */
  int clkdm_del_wkdep(struct clockdomain *clkdm1, struct clockdomain *clkdm2)
  {
  	struct clkdm_dep *cd;
  	int ret;
  
  	if (!clkdm1 || !clkdm2)
  		return -EINVAL;
  
  	cd = _clkdm_deps_lookup(clkdm2, clkdm1->wkdep_srcs);
  	if (IS_ERR(cd))
  		return PTR_ERR(cd);
  
  	pwrdm_lock(cd->clkdm->pwrdm.ptr);
  	ret = _clkdm_del_wkdep(clkdm1, clkdm2);
  	pwrdm_unlock(cd->clkdm->pwrdm.ptr);
  
  	return ret;
  }
  
  /**
   * clkdm_read_wkdep - read wakeup dependency state from clkdm2 to clkdm1
   * @clkdm1: wake this struct clockdomain * up (dependent)
   * @clkdm2: when this struct clockdomain * wakes up (source)
   *
   * Return 1 if a hardware wakeup dependency exists wherein @clkdm1 will be
   * awoken when @clkdm2 wakes up; 0 if dependency is not set; -EINVAL
   * if either clockdomain pointer is invalid; or -ENOENT if the hardware
   * is incapable.
   *
   * REVISIT: Currently this function only represents software-controllable
   * wakeup dependencies.  Wakeup dependencies fixed in hardware are not
   * yet handled here.
   */
  int clkdm_read_wkdep(struct clockdomain *clkdm1, struct clockdomain *clkdm2)
  {
  	struct clkdm_dep *cd;
  	int ret = 0;
  
  	if (!clkdm1 || !clkdm2)
  		return -EINVAL;
  
  	cd = _clkdm_deps_lookup(clkdm2, clkdm1->wkdep_srcs);
  	if (IS_ERR(cd))
  		ret = PTR_ERR(cd);
  
  	if (!arch_clkdm || !arch_clkdm->clkdm_read_wkdep)
  		ret = -EINVAL;
  
  	if (ret) {
  		pr_debug("clockdomain: hardware cannot set/clear wake up of %s when %s wakes up\n",
  			 clkdm1->name, clkdm2->name);
  		return ret;
  	}
  
  	/* XXX It's faster to return the wkdep_usecount */
  	return arch_clkdm->clkdm_read_wkdep(clkdm1, clkdm2);
  }
  
  /**
   * clkdm_clear_all_wkdeps - remove all wakeup dependencies from target clkdm
   * @clkdm: struct clockdomain * to remove all wakeup dependencies from
   *
   * Remove all inter-clockdomain wakeup dependencies that could cause
   * @clkdm to wake.  Intended to be used during boot to initialize the
   * PRCM to a known state, after all clockdomains are put into swsup idle
   * and woken up.  Returns -EINVAL if @clkdm pointer is invalid, or
   * 0 upon success.
   */
  int clkdm_clear_all_wkdeps(struct clockdomain *clkdm)
  {
  	if (!clkdm)
  		return -EINVAL;
  
  	if (!arch_clkdm || !arch_clkdm->clkdm_clear_all_wkdeps)
  		return -EINVAL;
  
  	return arch_clkdm->clkdm_clear_all_wkdeps(clkdm);
  }
  
  /**
   * clkdm_add_sleepdep - add a sleep dependency from clkdm2 to clkdm1
   * @clkdm1: prevent this struct clockdomain * from sleeping (dependent)
   * @clkdm2: when this struct clockdomain * is active (source)
   *
   * Prevent @clkdm1 from automatically going inactive (and then to
   * retention or off) if @clkdm2 is active.  Returns -EINVAL if
   * presented with invalid clockdomain pointers or called on a machine
   * that does not support software-configurable hardware sleep
   * dependencies, -ENOENT if the specified dependency cannot be set in
   * hardware, or 0 upon success.
   */
  int clkdm_add_sleepdep(struct clockdomain *clkdm1, struct clockdomain *clkdm2)
  {
  	struct clkdm_dep *cd;
  	int ret;
  
  	if (!clkdm1 || !clkdm2)
  		return -EINVAL;
  
  	cd = _clkdm_deps_lookup(clkdm2, clkdm1->wkdep_srcs);
  	if (IS_ERR(cd))
  		return PTR_ERR(cd);
  
  	pwrdm_lock(cd->clkdm->pwrdm.ptr);
  	ret = _clkdm_add_sleepdep(clkdm1, clkdm2);
  	pwrdm_unlock(cd->clkdm->pwrdm.ptr);
  
  	return ret;
  }
  
  /**
   * clkdm_del_sleepdep - remove a sleep dependency from clkdm2 to clkdm1
   * @clkdm1: prevent this struct clockdomain * from sleeping (dependent)
   * @clkdm2: when this struct clockdomain * is active (source)
   *
   * Allow @clkdm1 to automatically go inactive (and then to retention or
   * off), independent of the activity state of @clkdm2.  Returns -EINVAL
   * if presented with invalid clockdomain pointers or called on a machine
   * that does not support software-configurable hardware sleep dependencies,
   * -ENOENT if the specified dependency cannot be cleared in hardware, or
   * 0 upon success.
   */
  int clkdm_del_sleepdep(struct clockdomain *clkdm1, struct clockdomain *clkdm2)
  {
  	struct clkdm_dep *cd;
  	int ret;
  
  	if (!clkdm1 || !clkdm2)
  		return -EINVAL;
  
  	cd = _clkdm_deps_lookup(clkdm2, clkdm1->wkdep_srcs);
  	if (IS_ERR(cd))
  		return PTR_ERR(cd);
  
  	pwrdm_lock(cd->clkdm->pwrdm.ptr);
  	ret = _clkdm_del_sleepdep(clkdm1, clkdm2);
  	pwrdm_unlock(cd->clkdm->pwrdm.ptr);
  
  	return ret;
  }
  
  /**
   * clkdm_read_sleepdep - read sleep dependency state from clkdm2 to clkdm1
   * @clkdm1: prevent this struct clockdomain * from sleeping (dependent)
   * @clkdm2: when this struct clockdomain * is active (source)
   *
   * Return 1 if a hardware sleep dependency exists wherein @clkdm1 will
   * not be allowed to automatically go inactive if @clkdm2 is active;
   * 0 if @clkdm1's automatic power state inactivity transition is independent
   * of @clkdm2's; -EINVAL if either clockdomain pointer is invalid or called
   * on a machine that does not support software-configurable hardware sleep
   * dependencies; or -ENOENT if the hardware is incapable.
   *
   * REVISIT: Currently this function only represents software-controllable
   * sleep dependencies.	Sleep dependencies fixed in hardware are not
   * yet handled here.
   */
  int clkdm_read_sleepdep(struct clockdomain *clkdm1, struct clockdomain *clkdm2)
  {
  	struct clkdm_dep *cd;
  	int ret = 0;
  
  	if (!clkdm1 || !clkdm2)
  		return -EINVAL;
  
  	cd = _clkdm_deps_lookup(clkdm2, clkdm1->sleepdep_srcs);
  	if (IS_ERR(cd))
  		ret = PTR_ERR(cd);
  
  	if (!arch_clkdm || !arch_clkdm->clkdm_read_sleepdep)
  		ret = -EINVAL;
  
  	if (ret) {
  		pr_debug("clockdomain: hardware cannot set/clear sleep dependency affecting %s from %s\n",
  			 clkdm1->name, clkdm2->name);
  		return ret;
  	}
  
  	/* XXX It's faster to return the sleepdep_usecount */
  	return arch_clkdm->clkdm_read_sleepdep(clkdm1, clkdm2);
  }
  
  /**
   * clkdm_clear_all_sleepdeps - remove all sleep dependencies from target clkdm
   * @clkdm: struct clockdomain * to remove all sleep dependencies from
   *
   * Remove all inter-clockdomain sleep dependencies that could prevent
   * @clkdm from idling.  Intended to be used during boot to initialize the
   * PRCM to a known state, after all clockdomains are put into swsup idle
   * and woken up.  Returns -EINVAL if @clkdm pointer is invalid, or
   * 0 upon success.
   */
  int clkdm_clear_all_sleepdeps(struct clockdomain *clkdm)
  {
  	if (!clkdm)
  		return -EINVAL;
  
  	if (!arch_clkdm || !arch_clkdm->clkdm_clear_all_sleepdeps)
  		return -EINVAL;
  
  	return arch_clkdm->clkdm_clear_all_sleepdeps(clkdm);
  }
  
  /**
   * clkdm_sleep_nolock - force clockdomain sleep transition (lockless)
   * @clkdm: struct clockdomain *
   *
   * Instruct the CM to force a sleep transition on the specified
   * clockdomain @clkdm.  Only for use by the powerdomain code.  Returns
   * -EINVAL if @clkdm is NULL or if clockdomain does not support
   * software-initiated sleep; 0 upon success.
   */
  int clkdm_sleep_nolock(struct clockdomain *clkdm)
  {
  	int ret;
  
  	if (!clkdm)
  		return -EINVAL;
  
  	if (!(clkdm->flags & CLKDM_CAN_FORCE_SLEEP)) {
  		pr_debug("clockdomain: %s does not support forcing sleep via software\n",
  			 clkdm->name);
  		return -EINVAL;
  	}
  
  	if (!arch_clkdm || !arch_clkdm->clkdm_sleep)
  		return -EINVAL;
  
  	pr_debug("clockdomain: forcing sleep on %s\n", clkdm->name);
  
  	clkdm->_flags &= ~_CLKDM_FLAG_HWSUP_ENABLED;
  	ret = arch_clkdm->clkdm_sleep(clkdm);
  	ret |= pwrdm_state_switch_nolock(clkdm->pwrdm.ptr);
  
  	return ret;
  }
  
  /**
   * clkdm_sleep - force clockdomain sleep transition
   * @clkdm: struct clockdomain *
   *
   * Instruct the CM to force a sleep transition on the specified
   * clockdomain @clkdm.  Returns -EINVAL if @clkdm is NULL or if
   * clockdomain does not support software-initiated sleep; 0 upon
   * success.
   */
  int clkdm_sleep(struct clockdomain *clkdm)
  {
  	int ret;
  
  	pwrdm_lock(clkdm->pwrdm.ptr);
  	ret = clkdm_sleep_nolock(clkdm);
  	pwrdm_unlock(clkdm->pwrdm.ptr);
  
  	return ret;
  }
  
  /**
   * clkdm_wakeup_nolock - force clockdomain wakeup transition (lockless)
   * @clkdm: struct clockdomain *
   *
   * Instruct the CM to force a wakeup transition on the specified
   * clockdomain @clkdm.  Only for use by the powerdomain code.  Returns
   * -EINVAL if @clkdm is NULL or if the clockdomain does not support
   * software-controlled wakeup; 0 upon success.
   */
  int clkdm_wakeup_nolock(struct clockdomain *clkdm)
  {
  	int ret;
  
  	if (!clkdm)
  		return -EINVAL;
  
  	if (!(clkdm->flags & CLKDM_CAN_FORCE_WAKEUP)) {
  		pr_debug("clockdomain: %s does not support forcing wakeup via software\n",
  			 clkdm->name);
  		return -EINVAL;
  	}
  
  	if (!arch_clkdm || !arch_clkdm->clkdm_wakeup)
  		return -EINVAL;
  
  	pr_debug("clockdomain: forcing wakeup on %s\n", clkdm->name);
  
  	clkdm->_flags &= ~_CLKDM_FLAG_HWSUP_ENABLED;
  	ret = arch_clkdm->clkdm_wakeup(clkdm);
  	ret |= pwrdm_state_switch_nolock(clkdm->pwrdm.ptr);
  
  	return ret;
  }
  
  /**
   * clkdm_wakeup - force clockdomain wakeup transition
   * @clkdm: struct clockdomain *
   *
   * Instruct the CM to force a wakeup transition on the specified
   * clockdomain @clkdm.  Returns -EINVAL if @clkdm is NULL or if the
   * clockdomain does not support software-controlled wakeup; 0 upon
   * success.
   */
  int clkdm_wakeup(struct clockdomain *clkdm)
  {
  	int ret;
  
  	pwrdm_lock(clkdm->pwrdm.ptr);
  	ret = clkdm_wakeup_nolock(clkdm);
  	pwrdm_unlock(clkdm->pwrdm.ptr);
  
  	return ret;
  }
  
  /**
   * clkdm_allow_idle_nolock - enable hwsup idle transitions for clkdm
   * @clkdm: struct clockdomain *
   *
   * Allow the hardware to automatically switch the clockdomain @clkdm
   * into active or idle states, as needed by downstream clocks.  If the
   * clockdomain has any downstream clocks enabled in the clock
   * framework, wkdep/sleepdep autodependencies are added; this is so
   * device drivers can read and write to the device.  Only for use by
   * the powerdomain code.  No return value.
   */
  void clkdm_allow_idle_nolock(struct clockdomain *clkdm)
  {
  	if (!clkdm)
  		return;
  
  	if (!WARN_ON(!clkdm->forcewake_count))
  		clkdm->forcewake_count--;
  
  	if (clkdm->forcewake_count)
  		return;
  
  	if (!clkdm->usecount && (clkdm->flags & CLKDM_CAN_FORCE_SLEEP))
  		clkdm_sleep_nolock(clkdm);
  
  	if (!(clkdm->flags & CLKDM_CAN_ENABLE_AUTO))
  		return;
  
  	if (clkdm->flags & CLKDM_MISSING_IDLE_REPORTING)
  		return;
  
  	if (!arch_clkdm || !arch_clkdm->clkdm_allow_idle)
  		return;
  
  	pr_debug("clockdomain: enabling automatic idle transitions for %s\n",
  		 clkdm->name);
  
  	clkdm->_flags |= _CLKDM_FLAG_HWSUP_ENABLED;
  	arch_clkdm->clkdm_allow_idle(clkdm);
  	pwrdm_state_switch_nolock(clkdm->pwrdm.ptr);
  }
  
  /**
   * clkdm_allow_idle - enable hwsup idle transitions for clkdm
   * @clkdm: struct clockdomain *
   *
   * Allow the hardware to automatically switch the clockdomain @clkdm into
   * active or idle states, as needed by downstream clocks.  If the
   * clockdomain has any downstream clocks enabled in the clock
   * framework, wkdep/sleepdep autodependencies are added; this is so
   * device drivers can read and write to the device.  No return value.
   */
  void clkdm_allow_idle(struct clockdomain *clkdm)
  {
  	pwrdm_lock(clkdm->pwrdm.ptr);
  	clkdm_allow_idle_nolock(clkdm);
  	pwrdm_unlock(clkdm->pwrdm.ptr);
  }
  
  /**
   * clkdm_deny_idle - disable hwsup idle transitions for clkdm
   * @clkdm: struct clockdomain *
   *
   * Prevent the hardware from automatically switching the clockdomain
   * @clkdm into inactive or idle states.  If the clockdomain has
   * downstream clocks enabled in the clock framework, wkdep/sleepdep
   * autodependencies are removed.  Only for use by the powerdomain
   * code.  No return value.
   */
  void clkdm_deny_idle_nolock(struct clockdomain *clkdm)
  {
  	if (!clkdm)
  		return;
  
  	if (clkdm->forcewake_count++)
  		return;
  
  	if (clkdm->flags & CLKDM_CAN_FORCE_WAKEUP)
  		clkdm_wakeup_nolock(clkdm);
  
  	if (!(clkdm->flags & CLKDM_CAN_DISABLE_AUTO))
  		return;
  
  	if (clkdm->flags & CLKDM_MISSING_IDLE_REPORTING)
  		return;
  
  	if (!arch_clkdm || !arch_clkdm->clkdm_deny_idle)
  		return;
  
  	pr_debug("clockdomain: disabling automatic idle transitions for %s\n",
  		 clkdm->name);
  
  	clkdm->_flags &= ~_CLKDM_FLAG_HWSUP_ENABLED;
  	arch_clkdm->clkdm_deny_idle(clkdm);
  	pwrdm_state_switch_nolock(clkdm->pwrdm.ptr);
  }
  
  /**
   * clkdm_deny_idle - disable hwsup idle transitions for clkdm
   * @clkdm: struct clockdomain *
   *
   * Prevent the hardware from automatically switching the clockdomain
   * @clkdm into inactive or idle states.  If the clockdomain has
   * downstream clocks enabled in the clock framework, wkdep/sleepdep
   * autodependencies are removed.  No return value.
   */
  void clkdm_deny_idle(struct clockdomain *clkdm)
  {
  	pwrdm_lock(clkdm->pwrdm.ptr);
  	clkdm_deny_idle_nolock(clkdm);
  	pwrdm_unlock(clkdm->pwrdm.ptr);
  }
  
  /**
   * clkdm_in_hwsup - is clockdomain @clkdm have hardware-supervised idle enabled?
   * @clkdm: struct clockdomain *
   *
   * Returns true if clockdomain @clkdm currently has
   * hardware-supervised idle enabled, or false if it does not or if
   * @clkdm is NULL.  It is only valid to call this function after
   * clkdm_init() has been called.  This function does not actually read
   * bits from the hardware; it instead tests an in-memory flag that is
   * changed whenever the clockdomain code changes the auto-idle mode.
   */
  bool clkdm_in_hwsup(struct clockdomain *clkdm)
  {
  	bool ret;
  
  	if (!clkdm)
  		return false;
  
  	ret = (clkdm->_flags & _CLKDM_FLAG_HWSUP_ENABLED) ? true : false;
  
  	return ret;
  }
  
  /**
   * clkdm_missing_idle_reporting - can @clkdm enter autoidle even if in use?
   * @clkdm: struct clockdomain *
   *
   * Returns true if clockdomain @clkdm has the
   * CLKDM_MISSING_IDLE_REPORTING flag set, or false if not or @clkdm is
   * null.  More information is available in the documentation for the
   * CLKDM_MISSING_IDLE_REPORTING macro.
   */
  bool clkdm_missing_idle_reporting(struct clockdomain *clkdm)
  {
  	if (!clkdm)
  		return false;
  
  	return (clkdm->flags & CLKDM_MISSING_IDLE_REPORTING) ? true : false;
  }
  
  /* Public autodep handling functions (deprecated) */
  
  /**
   * clkdm_add_autodeps - add auto sleepdeps/wkdeps to clkdm upon clock enable
   * @clkdm: struct clockdomain *
   *
   * Add the "autodep" sleep & wakeup dependencies to clockdomain 'clkdm'
   * in hardware-supervised mode.  Meant to be called from clock framework
   * when a clock inside clockdomain 'clkdm' is enabled.	No return value.
   *
   * XXX autodeps are deprecated and should be removed at the earliest
   * opportunity
   */
  void clkdm_add_autodeps(struct clockdomain *clkdm)
  {
  	struct clkdm_autodep *autodep;
  
  	if (!autodeps || clkdm->flags & CLKDM_NO_AUTODEPS)
  		return;
  
  	for (autodep = autodeps; autodep->clkdm.ptr; autodep++) {
  		if (IS_ERR(autodep->clkdm.ptr))
  			continue;
  
  		pr_debug("clockdomain: %s: adding %s sleepdep/wkdep\n",
  			 clkdm->name, autodep->clkdm.ptr->name);
  
  		_clkdm_add_sleepdep(clkdm, autodep->clkdm.ptr);
  		_clkdm_add_wkdep(clkdm, autodep->clkdm.ptr);
  	}
  }
  
  /**
   * clkdm_del_autodeps - remove auto sleepdeps/wkdeps from clkdm
   * @clkdm: struct clockdomain *
   *
   * Remove the "autodep" sleep & wakeup dependencies from clockdomain 'clkdm'
   * in hardware-supervised mode.  Meant to be called from clock framework
   * when a clock inside clockdomain 'clkdm' is disabled.  No return value.
   *
   * XXX autodeps are deprecated and should be removed at the earliest
   * opportunity
   */
  void clkdm_del_autodeps(struct clockdomain *clkdm)
  {
  	struct clkdm_autodep *autodep;
  
  	if (!autodeps || clkdm->flags & CLKDM_NO_AUTODEPS)
  		return;
  
  	for (autodep = autodeps; autodep->clkdm.ptr; autodep++) {
  		if (IS_ERR(autodep->clkdm.ptr))
  			continue;
  
  		pr_debug("clockdomain: %s: removing %s sleepdep/wkdep\n",
  			 clkdm->name, autodep->clkdm.ptr->name);
  
  		_clkdm_del_sleepdep(clkdm, autodep->clkdm.ptr);
  		_clkdm_del_wkdep(clkdm, autodep->clkdm.ptr);
  	}
  }
  
  /* Clockdomain-to-clock/hwmod framework interface code */
  
  static int _clkdm_clk_hwmod_enable(struct clockdomain *clkdm)
  {
  	if (!clkdm || !arch_clkdm || !arch_clkdm->clkdm_clk_enable)
  		return -EINVAL;
  
  	pwrdm_lock(clkdm->pwrdm.ptr);
  
  	/*
  	 * For arch's with no autodeps, clkcm_clk_enable
  	 * should be called for every clock instance or hwmod that is
  	 * enabled, so the clkdm can be force woken up.
  	 */
  	clkdm->usecount++;
  	if (clkdm->usecount > 1 && autodeps) {
  		pwrdm_unlock(clkdm->pwrdm.ptr);
  		return 0;
  	}
  
  	arch_clkdm->clkdm_clk_enable(clkdm);
  	pwrdm_state_switch_nolock(clkdm->pwrdm.ptr);
  	pwrdm_unlock(clkdm->pwrdm.ptr);
  
  	pr_debug("clockdomain: %s: enabled\n", clkdm->name);
  
  	return 0;
  }
  
  /**
   * clkdm_clk_enable - add an enabled downstream clock to this clkdm
   * @clkdm: struct clockdomain *
   * @clk: struct clk * of the enabled downstream clock
   *
   * Increment the usecount of the clockdomain @clkdm and ensure that it
   * is awake before @clk is enabled.  Intended to be called by
   * clk_enable() code.  If the clockdomain is in software-supervised
   * idle mode, force the clockdomain to wake.  If the clockdomain is in
   * hardware-supervised idle mode, add clkdm-pwrdm autodependencies, to
   * ensure that devices in the clockdomain can be read from/written to
   * by on-chip processors.  Returns -EINVAL if passed null pointers;
   * returns 0 upon success or if the clockdomain is in hwsup idle mode.
   */
  int clkdm_clk_enable(struct clockdomain *clkdm, struct clk *clk)
  {
  	/*
  	 * XXX Rewrite this code to maintain a list of enabled
  	 * downstream clocks for debugging purposes?
  	 */
  
  	if (!clk)
  		return -EINVAL;
  
  	return _clkdm_clk_hwmod_enable(clkdm);
  }
  
  /**
   * clkdm_clk_disable - remove an enabled downstream clock from this clkdm
   * @clkdm: struct clockdomain *
   * @clk: struct clk * of the disabled downstream clock
   *
   * Decrement the usecount of this clockdomain @clkdm when @clk is
   * disabled.  Intended to be called by clk_disable() code.  If the
   * clockdomain usecount goes to 0, put the clockdomain to sleep
   * (software-supervised mode) or remove the clkdm autodependencies
   * (hardware-supervised mode).  Returns -EINVAL if passed null
   * pointers; -ERANGE if the @clkdm usecount underflows; or returns 0
   * upon success or if the clockdomain is in hwsup idle mode.
   */
  int clkdm_clk_disable(struct clockdomain *clkdm, struct clk *clk)
  {
  	if (!clkdm || !clk || !arch_clkdm || !arch_clkdm->clkdm_clk_disable)
  		return -EINVAL;
  
  	pwrdm_lock(clkdm->pwrdm.ptr);
  
  	/* corner case: disabling unused clocks */
  	if ((__clk_get_enable_count(clk) == 0) && clkdm->usecount == 0)
  		goto ccd_exit;
  
  	if (clkdm->usecount == 0) {
  		pwrdm_unlock(clkdm->pwrdm.ptr);
  		WARN_ON(1); /* underflow */
  		return -ERANGE;
  	}
  
  	clkdm->usecount--;
  	if (clkdm->usecount > 0) {
  		pwrdm_unlock(clkdm->pwrdm.ptr);
  		return 0;
  	}
  
  	arch_clkdm->clkdm_clk_disable(clkdm);
  	pwrdm_state_switch_nolock(clkdm->pwrdm.ptr);
  
  	pr_debug("clockdomain: %s: disabled\n", clkdm->name);
  
  ccd_exit:
  	pwrdm_unlock(clkdm->pwrdm.ptr);
  
  	return 0;
  }
  
  /**
   * clkdm_hwmod_enable - add an enabled downstream hwmod to this clkdm
   * @clkdm: struct clockdomain *
   * @oh: struct omap_hwmod * of the enabled downstream hwmod
   *
   * Increment the usecount of the clockdomain @clkdm and ensure that it
   * is awake before @oh is enabled. Intended to be called by
   * module_enable() code.
   * If the clockdomain is in software-supervised idle mode, force the
   * clockdomain to wake.  If the clockdomain is in hardware-supervised idle
   * mode, add clkdm-pwrdm autodependencies, to ensure that devices in the
   * clockdomain can be read from/written to by on-chip processors.
   * Returns -EINVAL if passed null pointers;
   * returns 0 upon success or if the clockdomain is in hwsup idle mode.
   */
  int clkdm_hwmod_enable(struct clockdomain *clkdm, struct omap_hwmod *oh)
  {
  	/* The clkdm attribute does not exist yet prior OMAP4 */
  	if (cpu_is_omap24xx() || cpu_is_omap34xx())
  		return 0;
  
  	/*
  	 * XXX Rewrite this code to maintain a list of enabled
  	 * downstream hwmods for debugging purposes?
  	 */
  
  	if (!oh)
  		return -EINVAL;
  
  	return _clkdm_clk_hwmod_enable(clkdm);
  }
  
  /**
   * clkdm_hwmod_disable - remove an enabled downstream hwmod from this clkdm
   * @clkdm: struct clockdomain *
   * @oh: struct omap_hwmod * of the disabled downstream hwmod
   *
   * Decrement the usecount of this clockdomain @clkdm when @oh is
   * disabled. Intended to be called by module_disable() code.
   * If the clockdomain usecount goes to 0, put the clockdomain to sleep
   * (software-supervised mode) or remove the clkdm autodependencies
   * (hardware-supervised mode).
   * Returns -EINVAL if passed null pointers; -ERANGE if the @clkdm usecount
   * underflows; or returns 0 upon success or if the clockdomain is in hwsup
   * idle mode.
   */
  int clkdm_hwmod_disable(struct clockdomain *clkdm, struct omap_hwmod *oh)
  {
  	/* The clkdm attribute does not exist yet prior OMAP4 */
  	if (cpu_is_omap24xx() || cpu_is_omap34xx())
  		return 0;
  
  	/*
  	 * XXX Rewrite this code to maintain a list of enabled
  	 * downstream hwmods for debugging purposes?
  	 */
  
  	if (!clkdm || !oh || !arch_clkdm || !arch_clkdm->clkdm_clk_disable)
  		return -EINVAL;
  
  	pwrdm_lock(clkdm->pwrdm.ptr);
  
  	if (clkdm->usecount == 0) {
  		pwrdm_unlock(clkdm->pwrdm.ptr);
  		WARN_ON(1); /* underflow */
  		return -ERANGE;
  	}
  
  	clkdm->usecount--;
  	if (clkdm->usecount > 0) {
  		pwrdm_unlock(clkdm->pwrdm.ptr);
  		return 0;
  	}
  
  	arch_clkdm->clkdm_clk_disable(clkdm);
  	pwrdm_state_switch_nolock(clkdm->pwrdm.ptr);
  	pwrdm_unlock(clkdm->pwrdm.ptr);
  
  	pr_debug("clockdomain: %s: disabled\n", clkdm->name);
  
  	return 0;
  }
  
  