mirror of
https://github.com/brain-hackers/u-boot-brain
synced 2024-08-31 22:39:08 +09:00
121 lines
4.9 KiB
C
121 lines
4.9 KiB
C
![]() |
/*
|
||
|
* Copyright (c) 2016, NVIDIA CORPORATION.
|
||
|
*
|
||
|
* SPDX-License-Identifier: GPL-2.0
|
||
|
*/
|
||
|
|
||
|
#ifndef _POWER_DOMAIN_H
|
||
|
#define _POWER_DOMAIN_H
|
||
|
|
||
|
/**
|
||
|
* A power domain is a portion of an SoC or chip that is powered by a
|
||
|
* switchable source of power. In many cases, software has control over the
|
||
|
* power domain, and can turn the power source on or off. This is typically
|
||
|
* done to save power by powering off unused devices, or to enable software
|
||
|
* sequencing of initial powerup at boot. This API provides a means for
|
||
|
* drivers to turn power domains on and off.
|
||
|
*
|
||
|
* A driver that implements UCLASS_POWER_DOMAIN is a power domain controller or
|
||
|
* provider. A controller will often implement multiple separate power domains,
|
||
|
* since the hardware it manages often has this capability.
|
||
|
* power-domain-uclass.h describes the interface which power domain controllers
|
||
|
* must implement.
|
||
|
*
|
||
|
* Depending on the power domain controller hardware, changing the state of a
|
||
|
* power domain may require performing related operations on other resources.
|
||
|
* For example, some power domains may require certain clocks to be enabled
|
||
|
* whenever the power domain is powered on, or during the time when the power
|
||
|
* domain is transitioning state. These details are implementation-specific
|
||
|
* and should ideally be encapsulated entirely within the provider driver, or
|
||
|
* configured through mechanisms (e.g. device tree) that do not require client
|
||
|
* drivers to provide extra configuration information.
|
||
|
*
|
||
|
* Power domain consumers/clients are the drivers for HW modules within the
|
||
|
* power domain. This header file describes the API used by those drivers.
|
||
|
*
|
||
|
* In many cases, a single complex IO controller (e.g. a PCIe controller) will
|
||
|
* be the sole logic contained within a power domain. In such cases, it is
|
||
|
* logical for the relevant device driver to directly control that power
|
||
|
* domain. In other cases, multiple controllers, each with their own driver,
|
||
|
* may be contained in a single power domain. Any logic require to co-ordinate
|
||
|
* between drivers for these multiple controllers is beyond the scope of this
|
||
|
* API at present. Equally, this API does not define or implement any policy
|
||
|
* by which power domains are managed.
|
||
|
*/
|
||
|
|
||
|
struct udevice;
|
||
|
|
||
|
/**
|
||
|
* struct power_domain - A handle to (allowing control of) a single power domain.
|
||
|
*
|
||
|
* Clients provide storage for power domain handles. The content of the
|
||
|
* structure is managed solely by the power domain API and power domain
|
||
|
* drivers. A power domain struct is initialized by "get"ing the power domain
|
||
|
* struct. The power domain struct is passed to all other power domain APIs to
|
||
|
* identify which power domain to operate upon.
|
||
|
*
|
||
|
* @dev: The device which implements the power domain.
|
||
|
* @id: The power domain ID within the provider.
|
||
|
*
|
||
|
* Currently, the power domain API assumes that a single integer ID is enough
|
||
|
* to identify and configure any power domain for any power domain provider. If
|
||
|
* this assumption becomes invalid in the future, the struct could be expanded
|
||
|
* to either (a) add more fields to allow power domain providers to store
|
||
|
* additional information, or (b) replace the id field with an opaque pointer,
|
||
|
* which the provider would dynamically allocate during its .of_xlate op, and
|
||
|
* process during is .request op. This may require the addition of an extra op
|
||
|
* to clean up the allocation.
|
||
|
*/
|
||
|
struct power_domain {
|
||
|
struct udevice *dev;
|
||
|
/*
|
||
|
* Written by of_xlate. We assume a single id is enough for now. In the
|
||
|
* future, we might add more fields here.
|
||
|
*/
|
||
|
unsigned long id;
|
||
|
};
|
||
|
|
||
|
/**
|
||
|
* power_domain_get - Get/request the power domain for a device.
|
||
|
*
|
||
|
* This looks up and requests a power domain. Each device is assumed to have
|
||
|
* a single (or, at least one) power domain associated with it somehow, and
|
||
|
* that domain, or the first/default domain. The mapping of client device to
|
||
|
* provider power domain may be via device-tree properties, board-provided
|
||
|
* mapping tables, or some other mechanism.
|
||
|
*
|
||
|
* @dev: The client device.
|
||
|
* @power_domain A pointer to a power domain struct to initialize.
|
||
|
* @return 0 if OK, or a negative error code.
|
||
|
*/
|
||
|
int power_domain_get(struct udevice *dev, struct power_domain *power_domain);
|
||
|
|
||
|
/**
|
||
|
* power_domain_free - Free a previously requested power domain.
|
||
|
*
|
||
|
* @power_domain: A power domain struct that was previously successfully
|
||
|
* requested by power_domain_get().
|
||
|
* @return 0 if OK, or a negative error code.
|
||
|
*/
|
||
|
int power_domain_free(struct power_domain *power_domain);
|
||
|
|
||
|
/**
|
||
|
* power_domain_on - Enable power to a power domain.
|
||
|
*
|
||
|
* @power_domain: A power domain struct that was previously successfully
|
||
|
* requested by power_domain_get().
|
||
|
* @return 0 if OK, or a negative error code.
|
||
|
*/
|
||
|
int power_domain_on(struct power_domain *power_domain);
|
||
|
|
||
|
/**
|
||
|
* power_domain_off - Disable power ot a power domain.
|
||
|
*
|
||
|
* @power_domain: A power domain struct that was previously successfully
|
||
|
* requested by power_domain_get().
|
||
|
* @return 0 if OK, or a negative error code.
|
||
|
*/
|
||
|
int power_domain_off(struct power_domain *power_domain);
|
||
|
|
||
|
#endif
|