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 when it is found that the 102 * device doesn't need a PM domain, else a negative error code. 103 */ 104 int dev_pm_domain_attach(struct device *dev, bool power_on) 105 { 106 int ret; 107 108 if (dev->pm_domain) 109 return 0; 110 111 ret = acpi_dev_pm_attach(dev, power_on); 112 if (!ret) 113 ret = genpd_dev_pm_attach(dev); 114 115 return ret < 0 ? ret : 0; 116 } 117 EXPORT_SYMBOL_GPL(dev_pm_domain_attach); 118 119 /** 120 * dev_pm_domain_attach_by_id - Associate a device with one of its PM domains. 121 * @dev: The device used to lookup the PM domain. 122 * @index: The index of the PM domain. 123 * 124 * As @dev may only be attached to a single PM domain, the backend PM domain 125 * provider creates a virtual device to attach instead. If attachment succeeds, 126 * the ->detach() callback in the struct dev_pm_domain are assigned by the 127 * corresponding backend attach function, as to deal with detaching of the 128 * created virtual device. 129 * 130 * This function should typically be invoked by a driver during the probe phase, 131 * in case its device requires power management through multiple PM domains. The 132 * driver may benefit from using the received device, to configure device-links 133 * towards its original device. Depending on the use-case and if needed, the 134 * links may be dynamically changed by the driver, which allows it to control 135 * the power to the PM domains independently from each other. 136 * 137 * Callers must ensure proper synchronization of this function with power 138 * management callbacks. 139 * 140 * Returns the virtual created device when successfully attached to its PM 141 * domain, NULL in case @dev don't need a PM domain, else an ERR_PTR(). 142 * Note that, to detach the returned virtual device, the driver shall call 143 * dev_pm_domain_detach() on it, typically during the remove phase. 144 */ 145 struct device *dev_pm_domain_attach_by_id(struct device *dev, 146 unsigned int index) 147 { 148 if (dev->pm_domain) 149 return ERR_PTR(-EEXIST); 150 151 return genpd_dev_pm_attach_by_id(dev, index); 152 } 153 EXPORT_SYMBOL_GPL(dev_pm_domain_attach_by_id); 154 155 /** 156 * dev_pm_domain_detach - Detach a device from its PM domain. 157 * @dev: Device to detach. 158 * @power_off: Used to indicate whether we should power off the device. 159 * 160 * This functions will reverse the actions from dev_pm_domain_attach() and 161 * dev_pm_domain_attach_by_id(), thus it detaches @dev from its PM domain. 162 * Typically it should be invoked during the remove phase, either from 163 * subsystem level code or from drivers. 164 * 165 * Callers must ensure proper synchronization of this function with power 166 * management callbacks. 167 */ 168 void dev_pm_domain_detach(struct device *dev, bool power_off) 169 { 170 if (dev->pm_domain && dev->pm_domain->detach) 171 dev->pm_domain->detach(dev, power_off); 172 } 173 EXPORT_SYMBOL_GPL(dev_pm_domain_detach); 174 175 /** 176 * dev_pm_domain_set - Set PM domain of a device. 177 * @dev: Device whose PM domain is to be set. 178 * @pd: PM domain to be set, or NULL. 179 * 180 * Sets the PM domain the device belongs to. The PM domain of a device needs 181 * to be set before its probe finishes (it's bound to a driver). 182 * 183 * This function must be called with the device lock held. 184 */ 185 void dev_pm_domain_set(struct device *dev, struct dev_pm_domain *pd) 186 { 187 if (dev->pm_domain == pd) 188 return; 189 190 WARN(pd && device_is_bound(dev), 191 "PM domains can only be changed for unbound devices\n"); 192 dev->pm_domain = pd; 193 device_pm_check_callbacks(dev); 194 } 195 EXPORT_SYMBOL_GPL(dev_pm_domain_set); 196