[PATCH 3/9] PM / Domains: Add APIs to attach/detach a power domain for a device

[Rafael J. Wysocki]

On Tuesday, August 26, 2014 02:07:11 PM Ulf Hansson wrote:
> To maintain scalability let's add common methods to attach and detach
> a power domain for a device, dev_pm_domain_attach|detach().
> 
> Typically dev_pm_domain_attach() shall be invoked from subsystem level
> code at the probe phase to try to attach a device to it's power domain.
> The reversed actions may be done a the remove phase and then by invoking
> dev_pm_domain_detach().
> 
> The supported power domains at this point are the ACPI and the generic
> power domains.
> 
> Signed-off-by: Ulf Hansson <ulf.hansson at linaro.org>
> ---
>  drivers/base/power/common.c | 58 +++++++++++++++++++++++++++++++++++++++++++++
>  include/linux/pm.h          | 14 +++++++++++
>  2 files changed, 72 insertions(+)
> 
> diff --git a/drivers/base/power/common.c b/drivers/base/power/common.c
> index df2e5ee..f544128 100644
> --- a/drivers/base/power/common.c
> +++ b/drivers/base/power/common.c
> @@ -11,6 +11,8 @@
>  #include <linux/export.h>
>  #include <linux/slab.h>
>  #include <linux/pm_clock.h>
> +#include <linux/acpi.h>
> +#include <linux/pm_domain.h>
>  
>  /**
>   * dev_pm_get_subsys_data - Create or refcount power.subsys_data for device.
> @@ -82,3 +84,59 @@ int dev_pm_put_subsys_data(struct device *dev)
>  	return ret;
>  }
>  EXPORT_SYMBOL_GPL(dev_pm_put_subsys_data);
> +
> +/**
> + * dev_pm_domain_attach - Attach a device to it's power 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 power domain. By iterating through
> + * the available alternatives we try to find a valid domain for the device.
> + *
> + * This function should typically be invoked from subsystem level code during
> + * the probe phase. Especially for those that's hold devices which requires
> + * power management through power domains.
> + *
> + * Callers must ensure proper synchronization of this function with power
> + * management callbacks.
> + *
> + * Returns 0 on successfully attached power domain or negative error code.
> + */
> +int dev_pm_domain_attach(struct device *dev, bool power_on)
> +{
> +	int ret;
> +
> +	ret = acpi_dev_pm_attach(dev, power_on);
> +	if (ret == -EPROBE_DEFER)

This doesn't seem to be possible today.  At least I'm not sure how it can
happen.

> +		return ret;
> +	else
> +		ret = genpd_dev_pm_attach(dev);
> +
> +	return ret;
> +}
> +EXPORT_SYMBOL_GPL(dev_pm_domain_attach);

On a more general note, are you sure that the place where we call
acpi_dev_pm_attach() will always be suitable for calling genpd_dev_pm_attach()?

> +
> +/**
> + * dev_pm_domain_detach - Detach a device from it's power domain.
> + * @dev: Device to attach.
> + * @power_off: Used to indicate whether we should power off the device.
> + *
> + * The @dev may be attached to a power domain. By iterating through the
> + * available alternatives we detach it from it's power domain.
> + *
> + * This functions will reverse the actions from dev_pm_domain_attach() and
> + * thus detach the @dev from it's power domain. Typically it should be invoked
> + * from subsystem level code during the remove phase.
> + *
> + * Callers must ensure proper synchronization of this function with power
> + * management callbacks.
> + *
> + * Returns 0 on successfully detached power domain or negative error code.
> + */
> +int dev_pm_domain_detach(struct device *dev, bool power_off)
> +{
> +	if (acpi_dev_pm_detach(dev, power_off))
> +		return genpd_dev_pm_detach(dev);
> +	return 0;
> +}
> +EXPORT_SYMBOL_GPL(dev_pm_domain_detach);
> diff --git a/include/linux/pm.h b/include/linux/pm.h
> index 72c0fe0..8176b07 100644
> --- a/include/linux/pm.h
> +++ b/include/linux/pm.h
> @@ -621,6 +621,20 @@ struct dev_pm_domain {
>  	struct dev_pm_ops	ops;
>  };
>  
> +#ifdef CONFIG_PM
> +extern int dev_pm_domain_attach(struct device *dev, bool power_on);
> +extern int dev_pm_domain_detach(struct device *dev, bool power_off);
> +#else
> +static inline int dev_pm_domain_attach(struct device *dev, bool power_on)
> +{
> +	return -ENODEV;
> +}
> +static inline int dev_pm_domain_detach(struct device *dev, bool power_off)
> +{
> +	return -ENODEV;
> +}
> +#endif
> +
>  /*
>   * The PM_EVENT_ messages are also used by drivers implementing the legacy
>   * suspend framework, based on the ->suspend() and ->resume() callbacks common
> 

-- 
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.