linux/drivers/base/power/common.c
Ulf Hansson 161e16a5e5 PM: domains: Add helper functions to attach/detach multiple PM domains
Attaching/detaching of a device to multiple PM domains has started to
become a common operation for many drivers, typically during ->probe() and
->remove(). In most cases, this has lead to lots of boilerplate code in the
drivers.

To fixup up the situation, let's introduce a pair of helper functions,
dev_pm_domain_attach|detach_list(), that driver can use instead of the
open-coding. Note that, it seems reasonable to limit the support for these
helpers to DT based platforms, at it's the only valid use case for now.

Suggested-by: Daniel Baluta <daniel.baluta@nxp.com>
Tested-by: Bryan O'Donoghue <bryan.odonoghue@linaro.org>
Tested-by: Iuliana Prodan <iuliana.prodan@nxp.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Link: https://lore.kernel.org/r/20240130123951.236243-2-ulf.hansson@linaro.org
2024-02-14 10:26:11 +01:00

386 lines
11 KiB
C

// SPDX-License-Identifier: GPL-2.0
/*
* drivers/base/power/common.c - Common device power management code.
*
* Copyright (C) 2011 Rafael J. Wysocki <rjw@sisk.pl>, Renesas Electronics Corp.
*/
#include <linux/kernel.h>
#include <linux/device.h>
#include <linux/export.h>
#include <linux/slab.h>
#include <linux/pm_clock.h>
#include <linux/acpi.h>
#include <linux/pm_domain.h>
#include "power.h"
/**
* dev_pm_get_subsys_data - Create or refcount power.subsys_data for device.
* @dev: Device to handle.
*
* If power.subsys_data is NULL, point it to a new object, otherwise increment
* its reference counter. Return 0 if new object has been created or refcount
* increased, otherwise negative error code.
*/
int dev_pm_get_subsys_data(struct device *dev)
{
struct pm_subsys_data *psd;
psd = kzalloc(sizeof(*psd), GFP_KERNEL);
if (!psd)
return -ENOMEM;
spin_lock_irq(&dev->power.lock);
if (dev->power.subsys_data) {
dev->power.subsys_data->refcount++;
} else {
spin_lock_init(&psd->lock);
psd->refcount = 1;
dev->power.subsys_data = psd;
pm_clk_init(dev);
psd = NULL;
}
spin_unlock_irq(&dev->power.lock);
/* kfree() verifies that its argument is nonzero. */
kfree(psd);
return 0;
}
EXPORT_SYMBOL_GPL(dev_pm_get_subsys_data);
/**
* dev_pm_put_subsys_data - Drop reference to power.subsys_data.
* @dev: Device to handle.
*
* If the reference counter of power.subsys_data is zero after dropping the
* reference, power.subsys_data is removed.
*/
void dev_pm_put_subsys_data(struct device *dev)
{
struct pm_subsys_data *psd;
spin_lock_irq(&dev->power.lock);
psd = dev_to_psd(dev);
if (!psd)
goto out;
if (--psd->refcount == 0)
dev->power.subsys_data = NULL;
else
psd = NULL;
out:
spin_unlock_irq(&dev->power.lock);
kfree(psd);
}
EXPORT_SYMBOL_GPL(dev_pm_put_subsys_data);
/**
* dev_pm_domain_attach - Attach a device to its PM domain.
* @dev: Device to attach.
* @power_on: Used to indicate whether we should power on the device.
*
* The @dev may only be attached to a single PM domain. By iterating through
* the available alternatives we try to find a valid PM domain for the device.
* As attachment succeeds, the ->detach() callback in the struct dev_pm_domain
* should be assigned by the corresponding attach function.
*
* This function should typically be invoked from subsystem level code during
* the probe phase. Especially for those that holds devices which requires
* power management through PM domains.
*
* Callers must ensure proper synchronization of this function with power
* management callbacks.
*
* Returns 0 on successfully attached PM domain, or when it is found that the
* device doesn't need a PM domain, else a negative error code.
*/
int dev_pm_domain_attach(struct device *dev, bool power_on)
{
int ret;
if (dev->pm_domain)
return 0;
ret = acpi_dev_pm_attach(dev, power_on);
if (!ret)
ret = genpd_dev_pm_attach(dev);
return ret < 0 ? ret : 0;
}
EXPORT_SYMBOL_GPL(dev_pm_domain_attach);
/**
* dev_pm_domain_attach_by_id - Associate a device with one of its PM domains.
* @dev: The device used to lookup the PM domain.
* @index: The index of the PM domain.
*
* As @dev may only be attached to a single PM domain, the backend PM domain
* provider creates a virtual device to attach instead. If attachment succeeds,
* the ->detach() callback in the struct dev_pm_domain are assigned by the
* corresponding backend attach function, as to deal with detaching of the
* created virtual device.
*
* This function should typically be invoked by a driver during the probe phase,
* in case its device requires power management through multiple PM domains. The
* driver may benefit from using the received device, to configure device-links
* towards its original device. Depending on the use-case and if needed, the
* links may be dynamically changed by the driver, which allows it to control
* the power to the PM domains independently from each other.
*
* Callers must ensure proper synchronization of this function with power
* management callbacks.
*
* Returns the virtual created device when successfully attached to its PM
* domain, NULL in case @dev don't need a PM domain, else an ERR_PTR().
* Note that, to detach the returned virtual device, the driver shall call
* dev_pm_domain_detach() on it, typically during the remove phase.
*/
struct device *dev_pm_domain_attach_by_id(struct device *dev,
unsigned int index)
{
if (dev->pm_domain)
return ERR_PTR(-EEXIST);
return genpd_dev_pm_attach_by_id(dev, index);
}
EXPORT_SYMBOL_GPL(dev_pm_domain_attach_by_id);
/**
* dev_pm_domain_attach_by_name - Associate a device with one of its PM domains.
* @dev: The device used to lookup the PM domain.
* @name: The name of the PM domain.
*
* For a detailed function description, see dev_pm_domain_attach_by_id().
*/
struct device *dev_pm_domain_attach_by_name(struct device *dev,
const char *name)
{
if (dev->pm_domain)
return ERR_PTR(-EEXIST);
return genpd_dev_pm_attach_by_name(dev, name);
}
EXPORT_SYMBOL_GPL(dev_pm_domain_attach_by_name);
/**
* dev_pm_domain_attach_list - Associate a device with its PM domains.
* @dev: The device used to lookup the PM domains for.
* @data: The data used for attaching to the PM domains.
* @list: An out-parameter with an allocated list of attached PM domains.
*
* This function helps to attach a device to its multiple PM domains. The
* caller, which is typically a driver's probe function, may provide a list of
* names for the PM domains that we should try to attach the device to, but it
* may also provide an empty list, in case the attach should be done for all of
* the available PM domains.
*
* Callers must ensure proper synchronization of this function with power
* management callbacks.
*
* Returns the number of attached PM domains or a negative error code in case of
* a failure. Note that, to detach the list of PM domains, the driver shall call
* dev_pm_domain_detach_list(), typically during the remove phase.
*/
int dev_pm_domain_attach_list(struct device *dev,
const struct dev_pm_domain_attach_data *data,
struct dev_pm_domain_list **list)
{
struct device_node *np = dev->of_node;
struct dev_pm_domain_list *pds;
struct device *pd_dev = NULL;
int ret, i, num_pds = 0;
bool by_id = true;
u32 pd_flags = data ? data->pd_flags : 0;
u32 link_flags = pd_flags & PD_FLAG_NO_DEV_LINK ? 0 :
DL_FLAG_STATELESS | DL_FLAG_PM_RUNTIME;
if (dev->pm_domain)
return -EEXIST;
/* For now this is limited to OF based platforms. */
if (!np)
return 0;
if (data && data->pd_names) {
num_pds = data->num_pd_names;
by_id = false;
} else {
num_pds = of_count_phandle_with_args(np, "power-domains",
"#power-domain-cells");
}
if (num_pds <= 0)
return 0;
pds = devm_kzalloc(dev, sizeof(*pds), GFP_KERNEL);
if (!pds)
return -ENOMEM;
pds->pd_devs = devm_kcalloc(dev, num_pds, sizeof(*pds->pd_devs),
GFP_KERNEL);
if (!pds->pd_devs)
return -ENOMEM;
pds->pd_links = devm_kcalloc(dev, num_pds, sizeof(*pds->pd_links),
GFP_KERNEL);
if (!pds->pd_links)
return -ENOMEM;
if (link_flags && pd_flags & PD_FLAG_DEV_LINK_ON)
link_flags |= DL_FLAG_RPM_ACTIVE;
for (i = 0; i < num_pds; i++) {
if (by_id)
pd_dev = dev_pm_domain_attach_by_id(dev, i);
else
pd_dev = dev_pm_domain_attach_by_name(dev,
data->pd_names[i]);
if (IS_ERR_OR_NULL(pd_dev)) {
ret = pd_dev ? PTR_ERR(pd_dev) : -ENODEV;
goto err_attach;
}
if (link_flags) {
struct device_link *link;
link = device_link_add(dev, pd_dev, link_flags);
if (!link) {
ret = -ENODEV;
goto err_link;
}
pds->pd_links[i] = link;
}
pds->pd_devs[i] = pd_dev;
}
pds->num_pds = num_pds;
*list = pds;
return num_pds;
err_link:
dev_pm_domain_detach(pd_dev, true);
err_attach:
while (--i >= 0) {
if (pds->pd_links[i])
device_link_del(pds->pd_links[i]);
dev_pm_domain_detach(pds->pd_devs[i], true);
}
return ret;
}
EXPORT_SYMBOL_GPL(dev_pm_domain_attach_list);
/**
* dev_pm_domain_detach - Detach a device from its PM domain.
* @dev: Device to detach.
* @power_off: Used to indicate whether we should power off the device.
*
* This functions will reverse the actions from dev_pm_domain_attach(),
* dev_pm_domain_attach_by_id() and dev_pm_domain_attach_by_name(), thus it
* detaches @dev from its PM domain. Typically it should be invoked during the
* remove phase, either from subsystem level code or from drivers.
*
* Callers must ensure proper synchronization of this function with power
* management callbacks.
*/
void dev_pm_domain_detach(struct device *dev, bool power_off)
{
if (dev->pm_domain && dev->pm_domain->detach)
dev->pm_domain->detach(dev, power_off);
}
EXPORT_SYMBOL_GPL(dev_pm_domain_detach);
/**
* dev_pm_domain_detach_list - Detach a list of PM domains.
* @list: The list of PM domains to detach.
*
* This function reverse the actions from dev_pm_domain_attach_list().
* Typically it should be invoked during the remove phase from drivers.
*
* Callers must ensure proper synchronization of this function with power
* management callbacks.
*/
void dev_pm_domain_detach_list(struct dev_pm_domain_list *list)
{
int i;
if (!list)
return;
for (i = 0; i < list->num_pds; i++) {
if (list->pd_links[i])
device_link_del(list->pd_links[i]);
dev_pm_domain_detach(list->pd_devs[i], true);
}
}
EXPORT_SYMBOL_GPL(dev_pm_domain_detach_list);
/**
* dev_pm_domain_start - Start the device through its PM domain.
* @dev: Device to start.
*
* This function should typically be called during probe by a subsystem/driver,
* when it needs to start its device from the PM domain's perspective. Note
* that, it's assumed that the PM domain is already powered on when this
* function is called.
*
* Returns 0 on success and negative error values on failures.
*/
int dev_pm_domain_start(struct device *dev)
{
if (dev->pm_domain && dev->pm_domain->start)
return dev->pm_domain->start(dev);
return 0;
}
EXPORT_SYMBOL_GPL(dev_pm_domain_start);
/**
* dev_pm_domain_set - Set PM domain of a device.
* @dev: Device whose PM domain is to be set.
* @pd: PM domain to be set, or NULL.
*
* Sets the PM domain the device belongs to. The PM domain of a device needs
* to be set before its probe finishes (it's bound to a driver).
*
* This function must be called with the device lock held.
*/
void dev_pm_domain_set(struct device *dev, struct dev_pm_domain *pd)
{
if (dev->pm_domain == pd)
return;
WARN(pd && device_is_bound(dev),
"PM domains can only be changed for unbound devices\n");
dev->pm_domain = pd;
device_pm_check_callbacks(dev);
}
EXPORT_SYMBOL_GPL(dev_pm_domain_set);
/**
* dev_pm_domain_set_performance_state - Request a new performance state.
* @dev: The device to make the request for.
* @state: Target performance state for the device.
*
* This function should be called when a new performance state needs to be
* requested for a device that is attached to a PM domain. Note that, the
* support for performance scaling for PM domains is optional.
*
* Returns 0 on success and when performance scaling isn't supported, negative
* error code on failure.
*/
int dev_pm_domain_set_performance_state(struct device *dev, unsigned int state)
{
if (dev->pm_domain && dev->pm_domain->set_performance_state)
return dev->pm_domain->set_performance_state(dev, state);
return 0;
}
EXPORT_SYMBOL_GPL(dev_pm_domain_set_performance_state);