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ACPI: x86: s2idle: Add a function to get LPS0 constraint for a device

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Other parts of the kernel may use LPS0 constraints information to make
decisions on what power state to put a device into.

Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
[ rjw: Rewrite kerneldoc, rearrange if () statement, edit subject and
  changelog ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
This commit is contained in:
Mario Limonciello 2023-08-18 14:40:07 -05:00 • committed by Rafael J. Wysocki
parent 4123398811
commit 1c2a66d47d
2 changed files with 30 additions and 0 deletions
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24
drivers/acpi/x86/s2idle.c
View file

@ -299,6 +299,30 @@ free_acpi_buffer:
ACPI_FREE(out_obj);
}
/**
* acpi_get_lps0_constraint - Get the LPS0 constraint for a device.
* @adev: Device to get the constraint for.
*
* The LPS0 constraint is the shallowest (minimum) power state in which the
* device can be so as to allow the platform as a whole to achieve additional
* energy conservation by utilizing a system-wide low-power state.
*
* Returns:
* - ACPI power state value of the constraint for @adev on success.
* - Otherwise, ACPI_STATE_UNKNOWN.
*/
int acpi_get_lps0_constraint(struct acpi_device *adev)
{
struct lpi_constraints *entry;
for_each_lpi_constraint(entry) {
if (adev->handle == entry->handle)
return entry->min_dstate;
}
return ACPI_STATE_UNKNOWN;
}
static void lpi_check_constraints(void)
{
struct lpi_constraints *entry;

6
include/linux/acpi.h
View file

@ -1109,6 +1109,12 @@ struct acpi_s2idle_dev_ops {
};
int acpi_register_lps0_dev(struct acpi_s2idle_dev_ops *arg);
void acpi_unregister_lps0_dev(struct acpi_s2idle_dev_ops *arg);
int acpi_get_lps0_constraint(struct acpi_device *adev);
#else /* CONFIG_SUSPEND && CONFIG_X86 */
static inline int acpi_get_lps0_constraint(struct device *dev)
{
return ACPI_STATE_UNKNOWN;
}
#endif /* CONFIG_SUSPEND && CONFIG_X86 */
#ifndef CONFIG_IA64
void arch_reserve_mem_area(acpi_physical_address addr, size_t size);