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* drivers/base/power/clock_ops.c - Generic clock manipulation PM callbacks
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* Copyright (c) 2011 Rafael J. Wysocki <rjw@sisk.pl>, Renesas Electronics Corp.
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* This file is released under the GPLv2.
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#include <linux/init.h>
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#include <linux/kernel.h>
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#include <linux/pm_clock.h>
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#include <linux/clk.h>
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#include <linux/slab.h>
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#include <linux/err.h>
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struct pm_clock_entry {
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struct list_head node;
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enum pce_status status;
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* pm_clk_acquire - Acquire a device clock.
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* @dev: Device whose clock is to be acquired.
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* @ce: PM clock entry corresponding to the clock.
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static void pm_clk_acquire(struct device *dev, struct pm_clock_entry *ce)
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ce->clk = clk_get(dev, ce->con_id);
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if (IS_ERR(ce->clk)) {
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ce->status = PCE_STATUS_ERROR;
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ce->status = PCE_STATUS_ACQUIRED;
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dev_dbg(dev, "Clock %s managed by runtime PM.\n", ce->con_id);
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* pm_clk_add - Start using a device clock for power management.
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* @dev: Device whose clock is going to be used for power management.
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* @con_id: Connection ID of the clock.
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* Add the clock represented by @con_id to the list of clocks used for
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* the power management of @dev.
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int pm_clk_add(struct device *dev, const char *con_id)
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struct pm_subsys_data *psd = dev_to_psd(dev);
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struct pm_clock_entry *ce;
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ce = kzalloc(sizeof(*ce), GFP_KERNEL);
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dev_err(dev, "Not enough memory for clock entry.\n");
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ce->con_id = kstrdup(con_id, GFP_KERNEL);
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"Not enough memory for clock connection ID.\n");
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pm_clk_acquire(dev, ce);
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spin_lock_irq(&psd->lock);
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list_add_tail(&ce->node, &psd->clock_list);
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spin_unlock_irq(&psd->lock);
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* __pm_clk_remove - Destroy PM clock entry.
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* @ce: PM clock entry to destroy.
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static void __pm_clk_remove(struct pm_clock_entry *ce)
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if (ce->status < PCE_STATUS_ERROR) {
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if (ce->status == PCE_STATUS_ENABLED)
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clk_disable(ce->clk);
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if (ce->status >= PCE_STATUS_ACQUIRED)
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* pm_clk_remove - Stop using a device clock for power management.
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* @dev: Device whose clock should not be used for PM any more.
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* @con_id: Connection ID of the clock.
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* Remove the clock represented by @con_id from the list of clocks used for
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* the power management of @dev.
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void pm_clk_remove(struct device *dev, const char *con_id)
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struct pm_subsys_data *psd = dev_to_psd(dev);
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struct pm_clock_entry *ce;
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spin_lock_irq(&psd->lock);
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list_for_each_entry(ce, &psd->clock_list, node) {
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if (!con_id && !ce->con_id)
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else if (!con_id || !ce->con_id)
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else if (!strcmp(con_id, ce->con_id))
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spin_unlock_irq(&psd->lock);
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spin_unlock_irq(&psd->lock);
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* pm_clk_init - Initialize a device's list of power management clocks.
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* @dev: Device to initialize the list of PM clocks for.
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* Initialize the lock and clock_list members of the device's pm_subsys_data
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void pm_clk_init(struct device *dev)
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struct pm_subsys_data *psd = dev_to_psd(dev);
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INIT_LIST_HEAD(&psd->clock_list);
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* pm_clk_create - Create and initialize a device's list of PM clocks.
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* @dev: Device to create and initialize the list of PM clocks for.
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* Allocate a struct pm_subsys_data object, initialize its lock and clock_list
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* members and make the @dev's power.subsys_data field point to it.
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int pm_clk_create(struct device *dev)
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int ret = dev_pm_get_subsys_data(dev);
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return ret < 0 ? ret : 0;
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* pm_clk_destroy - Destroy a device's list of power management clocks.
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* @dev: Device to destroy the list of PM clocks for.
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* Clear the @dev's power.subsys_data field, remove the list of clock entries
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* from the struct pm_subsys_data object pointed to by it before and free
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void pm_clk_destroy(struct device *dev)
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struct pm_subsys_data *psd = dev_to_psd(dev);
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struct pm_clock_entry *ce, *c;
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struct list_head list;
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INIT_LIST_HEAD(&list);
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spin_lock_irq(&psd->lock);
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list_for_each_entry_safe_reverse(ce, c, &psd->clock_list, node)
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list_move(&ce->node, &list);
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spin_unlock_irq(&psd->lock);
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dev_pm_put_subsys_data(dev);
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list_for_each_entry_safe_reverse(ce, c, &list, node) {
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#endif /* CONFIG_PM */
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#ifdef CONFIG_PM_RUNTIME
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* pm_clk_suspend - Disable clocks in a device's PM clock list.
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* @dev: Device to disable the clocks for.
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int pm_clk_suspend(struct device *dev)
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struct pm_subsys_data *psd = dev_to_psd(dev);
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struct pm_clock_entry *ce;
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dev_dbg(dev, "%s()\n", __func__);
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spin_lock_irqsave(&psd->lock, flags);
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list_for_each_entry_reverse(ce, &psd->clock_list, node) {
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if (ce->status < PCE_STATUS_ERROR) {
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if (ce->status == PCE_STATUS_ENABLED)
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clk_disable(ce->clk);
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ce->status = PCE_STATUS_ACQUIRED;
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spin_unlock_irqrestore(&psd->lock, flags);
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* pm_clk_resume - Enable clocks in a device's PM clock list.
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* @dev: Device to enable the clocks for.
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int pm_clk_resume(struct device *dev)
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struct pm_subsys_data *psd = dev_to_psd(dev);
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struct pm_clock_entry *ce;
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dev_dbg(dev, "%s()\n", __func__);
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spin_lock_irqsave(&psd->lock, flags);
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list_for_each_entry(ce, &psd->clock_list, node) {
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if (ce->status < PCE_STATUS_ERROR) {
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ce->status = PCE_STATUS_ENABLED;
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spin_unlock_irqrestore(&psd->lock, flags);
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* pm_clk_notify - Notify routine for device addition and removal.
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* @nb: Notifier block object this function is a member of.
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* @action: Operation being carried out by the caller.
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* @data: Device the routine is being run for.
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* For this function to work, @nb must be a member of an object of type
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* struct pm_clk_notifier_block containing all of the requisite data.
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* Specifically, the pm_domain member of that object is copied to the device's
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* pm_domain field and its con_ids member is used to populate the device's list
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* of PM clocks, depending on @action.
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* If the device's pm_domain field is already populated with a value different
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* from the one stored in the struct pm_clk_notifier_block object, the function
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static int pm_clk_notify(struct notifier_block *nb,
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unsigned long action, void *data)
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struct pm_clk_notifier_block *clknb;
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struct device *dev = data;
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dev_dbg(dev, "%s() %ld\n", __func__, action);
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clknb = container_of(nb, struct pm_clk_notifier_block, nb);
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case BUS_NOTIFY_ADD_DEVICE:
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error = pm_clk_create(dev);
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dev->pm_domain = clknb->pm_domain;
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if (clknb->con_ids[0]) {
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for (con_id = clknb->con_ids; *con_id; con_id++)
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pm_clk_add(dev, *con_id);
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pm_clk_add(dev, NULL);
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case BUS_NOTIFY_DEL_DEVICE:
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if (dev->pm_domain != clknb->pm_domain)
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dev->pm_domain = NULL;
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#else /* !CONFIG_PM_RUNTIME */
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* pm_clk_suspend - Disable clocks in a device's PM clock list.
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* @dev: Device to disable the clocks for.
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int pm_clk_suspend(struct device *dev)
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struct pm_subsys_data *psd = dev_to_psd(dev);
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struct pm_clock_entry *ce;
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dev_dbg(dev, "%s()\n", __func__);
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/* If there is no driver, the clocks are already disabled. */
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if (!psd || !dev->driver)
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spin_lock_irqsave(&psd->lock, flags);
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list_for_each_entry_reverse(ce, &psd->clock_list, node)
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clk_disable(ce->clk);
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spin_unlock_irqrestore(&psd->lock, flags);
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* pm_clk_resume - Enable clocks in a device's PM clock list.
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* @dev: Device to enable the clocks for.
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int pm_clk_resume(struct device *dev)
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struct pm_subsys_data *psd = dev_to_psd(dev);
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struct pm_clock_entry *ce;
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dev_dbg(dev, "%s()\n", __func__);
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/* If there is no driver, the clocks should remain disabled. */
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if (!psd || !dev->driver)
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spin_lock_irqsave(&psd->lock, flags);
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list_for_each_entry(ce, &psd->clock_list, node)
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spin_unlock_irqrestore(&psd->lock, flags);
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#endif /* CONFIG_PM */
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* enable_clock - Enable a device clock.
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* @dev: Device whose clock is to be enabled.
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* @con_id: Connection ID of the clock.
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static void enable_clock(struct device *dev, const char *con_id)
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clk = clk_get(dev, con_id);
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dev_info(dev, "Runtime PM disabled, clock forced on.\n");
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* disable_clock - Disable a device clock.
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* @dev: Device whose clock is to be disabled.
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* @con_id: Connection ID of the clock.
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static void disable_clock(struct device *dev, const char *con_id)
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clk = clk_get(dev, con_id);
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dev_info(dev, "Runtime PM disabled, clock forced off.\n");
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* pm_clk_notify - Notify routine for device addition and removal.
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* @nb: Notifier block object this function is a member of.
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* @action: Operation being carried out by the caller.
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* @data: Device the routine is being run for.
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* For this function to work, @nb must be a member of an object of type
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* struct pm_clk_notifier_block containing all of the requisite data.
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* Specifically, the con_ids member of that object is used to enable or disable
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* the device's clocks, depending on @action.
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static int pm_clk_notify(struct notifier_block *nb,
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unsigned long action, void *data)
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struct pm_clk_notifier_block *clknb;
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struct device *dev = data;
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dev_dbg(dev, "%s() %ld\n", __func__, action);
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clknb = container_of(nb, struct pm_clk_notifier_block, nb);
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case BUS_NOTIFY_BIND_DRIVER:
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if (clknb->con_ids[0]) {
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for (con_id = clknb->con_ids; *con_id; con_id++)
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enable_clock(dev, *con_id);
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enable_clock(dev, NULL);
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case BUS_NOTIFY_UNBOUND_DRIVER:
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if (clknb->con_ids[0]) {
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for (con_id = clknb->con_ids; *con_id; con_id++)
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disable_clock(dev, *con_id);
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disable_clock(dev, NULL);
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#endif /* !CONFIG_PM_RUNTIME */
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* pm_clk_add_notifier - Add bus type notifier for power management clocks.
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* @bus: Bus type to add the notifier to.
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* @clknb: Notifier to be added to the given bus type.
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* The nb member of @clknb is not expected to be initialized and its
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* notifier_call member will be replaced with pm_clk_notify(). However,
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* the remaining members of @clknb should be populated prior to calling this
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void pm_clk_add_notifier(struct bus_type *bus,
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struct pm_clk_notifier_block *clknb)
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clknb->nb.notifier_call = pm_clk_notify;
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bus_register_notifier(bus, &clknb->nb);