The PCI firmware specification includes support for a _DSM function to negotiate aux power to be provided to the device while it is in D3cold. "The Request D3cold Aux Power Limit function describes how a device driver conveys its auxiliary power requirements to the host platform when the device is in D3cold. The system firmware responds with a value indicating whether the request can be supported. The power request is specific to the Auxiliary power supply; main power may be removed while in D3cold. A device must not draw any more power than what has been negotiated via this mechanism after entering D3cold" Add API for callers to utilize this _DSM. Link: https://members.pcisig.com/wg/PCI-SIG/document/15350 PCI Firmware specification 3.3, section 4.6.10 Signed-off-by: Mario Limonciello <mario.limonciello@xxxxxxx> --- drivers/pci/pci-acpi.c | 54 ++++++++++++++++++++++++++++++++++++++++ include/linux/pci-acpi.h | 7 ++++++ 2 files changed, 61 insertions(+) diff --git a/drivers/pci/pci-acpi.c b/drivers/pci/pci-acpi.c index bea72e807817..257858a6719e 100644 --- a/drivers/pci/pci-acpi.c +++ b/drivers/pci/pci-acpi.c @@ -1348,6 +1348,60 @@ static struct acpi_device *acpi_pci_find_companion(struct device *dev) return adev; } +/** + * pci_acpi_request_aux_power_for_d3cold - Request auxiliary power for D3cold + * @pdev: PCI device to request power for + * @arg: mW requested + * + * This function requests auxiliary power for a PCI device in D3cold state + * when main power is removed above the value guaranteed by PCI specification. + * + * Return: + * 0 on success + * -ENODEV when the device does not support the _DSM + * -EIO on ACPI call failure + * -EACCESS when the request was denied + * Positive value corresponding to platform requested retry interval in seconds + */ +int pci_acpi_request_aux_power_for_d3cold(struct pci_dev *pdev, int arg) +{ + struct acpi_device *adev = ACPI_COMPANION(&pdev->dev); + union acpi_object *obj; + union acpi_object argv4 = { + .integer.type = ACPI_TYPE_INTEGER, + .integer.value = arg, + }; + int val; + + if (!acpi_check_dsm(adev->handle, &pci_acpi_dsm_guid, + pci_acpi_dsm_rev, + 1 << DSM_PCI_REQUEST_D3COLD_AUX_POWER)) + return -ENODEV; + + obj = acpi_evaluate_dsm_typed(adev->handle, &pci_acpi_dsm_guid, + pci_acpi_dsm_rev, + DSM_PCI_REQUEST_D3COLD_AUX_POWER, + &argv4, ACPI_TYPE_INTEGER); + if (!obj) + return -EIO; + + val = obj->integer.value; + ACPI_FREE(obj); + + switch (val) { + case PCI_D3COLD_AUX_DENIED: + return -EACCES; + case PCI_D3COLD_AUX_GRANTED: + case PCI_D3COLD_AUX_NO_MAIN_POWER_REMOVAL: + return 0; + default: + break; + } + + return val; +} +EXPORT_SYMBOL_GPL(pci_acpi_request_aux_power_for_d3cold); + /** * pci_acpi_optimize_delay - optimize PCI D3 and D3cold delay from ACPI * @pdev: the PCI device whose delay is to be updated diff --git a/include/linux/pci-acpi.h b/include/linux/pci-acpi.h index 7966ef8f14b3..bc6372bcb7d6 100644 --- a/include/linux/pci-acpi.h +++ b/include/linux/pci-acpi.h @@ -122,6 +122,13 @@ extern const int pci_acpi_dsm_rev; #define DSM_PCI_DEVICE_NAME 0x07 #define DSM_PCI_POWER_ON_RESET_DELAY 0x08 #define DSM_PCI_DEVICE_READINESS_DURATIONS 0x09 +#define DSM_PCI_REQUEST_D3COLD_AUX_POWER 0x0A + +#define PCI_D3COLD_AUX_DENIED 0 +#define PCI_D3COLD_AUX_GRANTED 1 +#define PCI_D3COLD_AUX_NO_MAIN_POWER_REMOVAL 2 + +int pci_acpi_request_aux_power_for_d3cold(struct pci_dev *pdev, int arg); #ifdef CONFIG_PCIE_EDR void pci_acpi_add_edr_notifier(struct pci_dev *pdev); -- 2.34.1
