powerpc/powernv/pci: Add helper to find ioda_pe from BDFN

For each PHB we maintain a reverse-map that can be used to find the
PE that a BDFN is currently mapped to. Add a helper for doing this
lookup so we can check if a PE has been configured without looking
at pdn->pe_number.
Signed-off-by: Oliver O'Halloran <oohall@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200417073508.30356-2-oohall@gmail.com

arch/powerpc/platforms/powernv/pci-ioda.c

@@ -660,6 +660,16 @@ static int pnv_ioda_get_pe_state(struct pnv_phb *phb, int pe_no)
 	return state;
 }
 
+struct pnv_ioda_pe *pnv_pci_bdfn_to_pe(struct pnv_phb *phb, u16 bdfn)
+{
+	int pe_number = phb->ioda.pe_rmap[bdfn];
+
+	if (pe_number == IODA_INVALID_PE)
+		return NULL;
+
+	return &phb->ioda.pe_array[pe_number];
+}
+
 struct pnv_ioda_pe *pnv_ioda_get_pe(struct pci_dev *dev)
 {
 	struct pci_controller *hose = pci_bus_to_host(dev->bus);

arch/powerpc/platforms/powernv/pci.h

@@ -208,6 +208,7 @@ extern int pnv_eeh_phb_reset(struct pci_controller *hose, int option);
 
 extern int pnv_setup_msi_irqs(struct pci_dev *pdev, int nvec, int type);
 extern void pnv_teardown_msi_irqs(struct pci_dev *pdev);
+extern struct pnv_ioda_pe *pnv_pci_bdfn_to_pe(struct pnv_phb *phb, u16 bdfn);
 extern struct pnv_ioda_pe *pnv_ioda_get_pe(struct pci_dev *dev);
 extern void pnv_set_msi_irq_chip(struct pnv_phb *phb, unsigned int virq);
 extern unsigned long pnv_pci_ioda2_get_table_size(__u32 page_shift,