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