1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * drivers/base/power/common.c - Common device power management code. 4 * 5 * Copyright (C) 2011 Rafael J. Wysocki <rjw@sisk.pl>, Renesas Electronics Corp. 6 */ 7 #include <linux/kernel.h> 8 #include <linux/device.h> 9 #include <linux/export.h> 10 #include <linux/slab.h> 11 #include <linux/pm_clock.h> 12 #include <linux/acpi.h> 13 #include <linux/pm_domain.h> 14 15 #include "power.h" 16 17 /** 18 * dev_pm_get_subsys_data - Create or refcount power.subsys_data for device. 19 * @dev: Device to handle. 20 * 21 * If power.subsys_data is NULL, point it to a new object, otherwise increment 22 * its reference counter. Return 0 if new object has been created or refcount 23 * increased, otherwise negative error code. 24 */ 25 int dev_pm_get_subsys_data(struct device *dev) 26 { 27 struct pm_subsys_data *psd; 28 29 psd = kzalloc(sizeof(*psd), GFP_KERNEL); 30 if (!psd) 31 return -ENOMEM; 32 33 spin_lock_irq(&dev->power.lock); 34 35 if (dev->power.subsys_data) { 36 dev->power.subsys_data->refcount++; 37 } else { 38 spin_lock_init(&psd->lock); 39 psd->refcount = 1; 40 dev->power.subsys_data = psd; 41 pm_clk_init(dev); 42 psd = NULL; 43 } 44 45 spin_unlock_irq(&dev->power.lock); 46 47 /* kfree() verifies that its argument is nonzero. */ 48 kfree(psd); 49 50 return 0; 51 } 52 EXPORT_SYMBOL_GPL(dev_pm_get_subsys_data); 53 54 /** 55 * dev_pm_put_subsys_data - Drop reference to power.subsys_data. 56 * @dev: Device to handle. 57 * 58 * If the reference counter of power.subsys_data is zero after dropping the 59 * reference, power.subsys_data is removed. 60 */ 61 void dev_pm_put_subsys_data(struct device *dev) 62 { 63 struct pm_subsys_data *psd; 64 65 spin_lock_irq(&dev->power.lock); 66 67 psd = dev_to_psd(dev); 68 if (!psd) 69 goto out; 70 71 if (--psd->refcount == 0) 72 dev->power.subsys_data = NULL; 73 else 74 psd = NULL; 75 76 out: 77 spin_unlock_irq(&dev->power.lock); 78 kfree(psd); 79 } 80 EXPORT_SYMBOL_GPL(dev_pm_put_subsys_data); 81 82 /** 83 * dev_pm_domain_attach - Attach a device to its PM domain. 84 * @dev: Device to attach. 85 * @power_on: Used to indicate whether we should power on the device. 86 * 87 * The @dev may only be attached to a single PM domain. By iterating through 88 * the available alternatives we try to find a valid PM domain for the device. 89 * As attachment succeeds, the ->detach() callback in the struct dev_pm_domain 90 * should be assigned by the corresponding attach function. 91 * 92 * This function should typically be invoked from subsystem level code during 93 * the probe phase. Especially for those that holds devices which requires 94 * power management through PM domains. 95 * 96 * Callers must ensure proper synchronization of this function with power 97 * management callbacks. 98 * 99 * Returns 0 on successfully attached PM domain, or when it is found that the 100 * device doesn't need a PM domain, else a negative error code. 101 */ 102 int dev_pm_domain_attach(struct device *dev, bool power_on) 103 { 104 int ret; 105 106 if (dev->pm_domain) 107 return 0; 108 109 ret = acpi_dev_pm_attach(dev, power_on); 110 if (!ret) 111 ret = genpd_dev_pm_attach(dev); 112 113 return ret < 0 ? ret : 0; 114 } 115 EXPORT_SYMBOL_GPL(dev_pm_domain_attach); 116 117 /** 118 * dev_pm_domain_attach_by_id - Associate a device with one of its PM domains. 119 * @dev: The device used to lookup the PM domain. 120 * @index: The index of the PM domain. 121 * 122 * As @dev may only be attached to a single PM domain, the backend PM domain 123 * provider creates a virtual device to attach instead. If attachment succeeds, 124 * the ->detach() callback in the struct dev_pm_domain are assigned by the 125 * corresponding backend attach function, as to deal with detaching of the 126 * created virtual device. 127 * 128 * This function should typically be invoked by a driver during the probe phase, 129 * in case its device requires power management through multiple PM domains. The 130 * driver may benefit from using the received device, to configure device-links 131 * towards its original device. Depending on the use-case and if needed, the 132 * links may be dynamically changed by the driver, which allows it to control 133 * the power to the PM domains independently from each other. 134 * 135 * Callers must ensure proper synchronization of this function with power 136 * management callbacks. 137 * 138 * Returns the virtual created device when successfully attached to its PM 139 * domain, NULL in case @dev don't need a PM domain, else an ERR_PTR(). 140 * Note that, to detach the returned virtual device, the driver shall call 141 * dev_pm_domain_detach() on it, typically during the remove phase. 142 */ 143 struct device *dev_pm_domain_attach_by_id(struct device *dev, 144 unsigned int index) 145 { 146 if (dev->pm_domain) 147 return ERR_PTR(-EEXIST); 148 149 return genpd_dev_pm_attach_by_id(dev, index); 150 } 151 EXPORT_SYMBOL_GPL(dev_pm_domain_attach_by_id); 152 153 /** 154 * dev_pm_domain_attach_by_name - Associate a device with one of its PM domains. 155 * @dev: The device used to lookup the PM domain. 156 * @name: The name of the PM domain. 157 * 158 * For a detailed function description, see dev_pm_domain_attach_by_id(). 159 */ 160 struct device *dev_pm_domain_attach_by_name(struct device *dev, 161 const char *name) 162 { 163 if (dev->pm_domain) 164 return ERR_PTR(-EEXIST); 165 166 return genpd_dev_pm_attach_by_name(dev, name); 167 } 168 EXPORT_SYMBOL_GPL(dev_pm_domain_attach_by_name); 169 170 /** 171 * dev_pm_domain_detach - Detach a device from its PM domain. 172 * @dev: Device to detach. 173 * @power_off: Used to indicate whether we should power off the device. 174 * 175 * This functions will reverse the actions from dev_pm_domain_attach() and 176 * dev_pm_domain_attach_by_id(), thus it detaches @dev from its PM domain. 177 * Typically it should be invoked during the remove phase, either from 178 * subsystem level code or from drivers. 179 * 180 * Callers must ensure proper synchronization of this function with power 181 * management callbacks. 182 */ 183 void dev_pm_domain_detach(struct device *dev, bool power_off) 184 { 185 if (dev->pm_domain && dev->pm_domain->detach) 186 dev->pm_domain->detach(dev, power_off); 187 } 188 EXPORT_SYMBOL_GPL(dev_pm_domain_detach); 189 190 /** 191 * dev_pm_domain_set - Set PM domain of a device. 192 * @dev: Device whose PM domain is to be set. 193 * @pd: PM domain to be set, or NULL. 194 * 195 * Sets the PM domain the device belongs to. The PM domain of a device needs 196 * to be set before its probe finishes (it's bound to a driver). 197 * 198 * This function must be called with the device lock held. 199 */ 200 void dev_pm_domain_set(struct device *dev, struct dev_pm_domain *pd) 201 { 202 if (dev->pm_domain == pd) 203 return; 204 205 WARN(pd && device_is_bound(dev), 206 "PM domains can only be changed for unbound devices\n"); 207 dev->pm_domain = pd; 208 device_pm_check_callbacks(dev); 209 } 210 EXPORT_SYMBOL_GPL(dev_pm_domain_set); 211