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Subject[PATCH v5 1/2] PCI: Add pci_pr3_present() helper to check Power Resource for D3hot
Date
Add pci_pr3_present() to check whether the platform supplies _PR3 to
tell us which power resources the device depends on when in D3hot. This
information is useful to let drivers choose different runtime suspend
behavior. A user will be add in next patch.

This is mostly the same as nouveau_pr3_present().

Signed-off-by: Kai-Heng Feng <kai.heng.feng@canonical.com>
---
v5:
- Add wording suggestion from Bjorn.
v4:
- Let caller to find its upstream port device.

drivers/pci/pci.c | 16 ++++++++++++++++
include/linux/pci.h | 2 ++
2 files changed, 18 insertions(+)

diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index e7982af9a5d8..d03f624d8928 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -5856,6 +5856,22 @@ int pci_set_vga_state(struct pci_dev *dev, bool decode,
return 0;
}

+bool pci_pr3_present(struct pci_dev *pdev)
+{
+ struct acpi_device *adev;
+
+ if (acpi_disabled)
+ return false;
+
+ adev = ACPI_COMPANION(&pdev->dev);
+ if (!adev)
+ return false;
+
+ return adev->power.flags.power_resources &&
+ acpi_has_method(adev->handle, "_PR3");
+}
+EXPORT_SYMBOL_GPL(pci_pr3_present);
+
/**
* pci_add_dma_alias - Add a DMA devfn alias for a device
* @dev: the PCI device for which alias is added
diff --git a/include/linux/pci.h b/include/linux/pci.h
index f9088c89a534..1d15c5d49cdd 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -2310,9 +2310,11 @@ struct irq_domain *pci_host_bridge_acpi_msi_domain(struct pci_bus *bus);

void
pci_msi_register_fwnode_provider(struct fwnode_handle *(*fn)(struct device *));
+bool pci_pr3_present(struct pci_dev *pdev);
#else
static inline struct irq_domain *
pci_host_bridge_acpi_msi_domain(struct pci_bus *bus) { return NULL; }
+static bool pci_pr3_present(struct pci_dev *pdev) { return false; }
#endif

#ifdef CONFIG_EEH
--
2.17.1
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