1 /* 2 * drivers/base/power/common.c - Common device power management code. 3 * 4 * Copyright (C) 2011 Rafael J. Wysocki <rjw@sisk.pl>, Renesas Electronics Corp. 5 * 6 * This file is released under the GPLv2. 7 */ 8 9 #include <linux/kernel.h> 10 #include <linux/device.h> 11 #include <linux/export.h> 12 #include <linux/slab.h> 13 #include <linux/pm_clock.h> 14 #include <linux/acpi.h> 15 #include <linux/pm_domain.h> 16 17 #include "power.h" 18 19 /** 20 * dev_pm_get_subsys_data - Create or refcount power.subsys_data for device. 21 * @dev: Device to handle. 22 * 23 * If power.subsys_data is NULL, point it to a new object, otherwise increment 24 * its reference counter. Return 0 if new object has been created or refcount 25 * increased, otherwise negative error code. 26 */ 27 int dev_pm_get_subsys_data(struct device *dev) 28 { 29 struct pm_subsys_data *psd; 30 31 psd = kzalloc(sizeof(*psd), GFP_KERNEL); 32 if (!psd) 33 return -ENOMEM; 34 35 spin_lock_irq(&dev->power.lock); 36 37 if (dev->power.subsys_data) { 38 dev->power.subsys_data->refcount++; 39 } else { 40 spin_lock_init(&psd->lock); 41 psd->refcount = 1; 42 dev->power.subsys_data = psd; 43 pm_clk_init(dev); 44 psd = NULL; 45 } 46 47 spin_unlock_irq(&dev->power.lock); 48 49 /* kfree() verifies that its argument is nonzero. */ 50 kfree(psd); 51 52 return 0; 53 } 54 EXPORT_SYMBOL_GPL(dev_pm_get_subsys_data); 55 56 /** 57 * dev_pm_put_subsys_data - Drop reference to power.subsys_data. 58 * @dev: Device to handle. 59 * 60 * If the reference counter of power.subsys_data is zero after dropping the 61 * reference, power.subsys_data is removed. 62 */ 63 void dev_pm_put_subsys_data(struct device *dev) 64 { 65 struct pm_subsys_data *psd; 66 67 spin_lock_irq(&dev->power.lock); 68 69 psd = dev_to_psd(dev); 70 if (!psd) 71 goto out; 72 73 if (--psd->refcount == 0) 74 dev->power.subsys_data = NULL; 75 else 76 psd = NULL; 77 78 out: 79 spin_unlock_irq(&dev->power.lock); 80 kfree(psd); 81 } 82 EXPORT_SYMBOL_GPL(dev_pm_put_subsys_data); 83 84 /** 85 * dev_pm_domain_attach - Attach a device to its PM domain. 86 * @dev: Device to attach. 87 * @power_on: Used to indicate whether we should power on the device. 88 * 89 * The @dev may only be attached to a single PM domain. By iterating through 90 * the available alternatives we try to find a valid PM domain for the device. 91 * As attachment succeeds, the ->detach() callback in the struct dev_pm_domain 92 * should be assigned by the corresponding attach function. 93 * 94 * This function should typically be invoked from subsystem level code during 95 * the probe phase. Especially for those that holds devices which requires 96 * power management through PM domains. 97 * 98 * Callers must ensure proper synchronization of this function with power 99 * management callbacks. 100 * 101 * Returns 0 on successfully attached PM domain or negative error code. 102 */ 103 int dev_pm_domain_attach(struct device *dev, bool power_on) 104 { 105 int ret; 106 107 ret = acpi_dev_pm_attach(dev, power_on); 108 if (ret) 109 ret = genpd_dev_pm_attach(dev); 110 111 return ret; 112 } 113 EXPORT_SYMBOL_GPL(dev_pm_domain_attach); 114 115 /** 116 * dev_pm_domain_detach - Detach a device from its PM domain. 117 * @dev: Device to detach. 118 * @power_off: Used to indicate whether we should power off the device. 119 * 120 * This functions will reverse the actions from dev_pm_domain_attach() and thus 121 * try to detach the @dev from its PM domain. Typically it should be invoked 122 * from subsystem level code during the remove phase. 123 * 124 * Callers must ensure proper synchronization of this function with power 125 * management callbacks. 126 */ 127 void dev_pm_domain_detach(struct device *dev, bool power_off) 128 { 129 if (dev->pm_domain && dev->pm_domain->detach) 130 dev->pm_domain->detach(dev, power_off); 131 } 132 EXPORT_SYMBOL_GPL(dev_pm_domain_detach); 133 134 /** 135 * dev_pm_domain_set - Set PM domain of a device. 136 * @dev: Device whose PM domain is to be set. 137 * @pd: PM domain to be set, or NULL. 138 * 139 * Sets the PM domain the device belongs to. The PM domain of a device needs 140 * to be set before its probe finishes (it's bound to a driver). 141 * 142 * This function must be called with the device lock held. 143 */ 144 void dev_pm_domain_set(struct device *dev, struct dev_pm_domain *pd) 145 { 146 if (dev->pm_domain == pd) 147 return; 148 149 WARN(pd && device_is_bound(dev), 150 "PM domains can only be changed for unbound devices\n"); 151 dev->pm_domain = pd; 152 device_pm_check_callbacks(dev); 153 } 154 EXPORT_SYMBOL_GPL(dev_pm_domain_set); 155