diff options
Diffstat (limited to 'include/power-domain.h')
| -rw-r--r-- | include/power-domain.h | 120 |
1 files changed, 120 insertions, 0 deletions
diff --git a/include/power-domain.h b/include/power-domain.h new file mode 100644 index 00000000000..10999790b56 --- /dev/null +++ b/include/power-domain.h @@ -0,0 +1,120 @@ +/* + * 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 |