powerpc/powernv: Introduce pnv_pci_get_slot_id()

This introduces pnv_pci_get_slot_id() to get the hotpluggable PCI
slot ID from the corresponding device node. It will be used by
hotplug driver.

Requested-by: Andrew Donnellan <[e-mail]>
Signed-off-by: Gavin Shan <[e-mail]>
Signed-off-by: Michael Ellerman <[e-mail]>

arch/powerpc/include/asm/pnv-pci.h

···
 #define PCI_SLOT_ID(phb_id, bdfn)	\
 	(PCI_SLOT_ID_PREFIX | ((uint64_t)(bdfn) << 16) | (phb_id))
 
+extern int pnv_pci_get_slot_id(struct device_node *np, uint64_t *id);
+
 int pnv_phb_to_cxl_mode(struct pci_dev *dev, uint64_t mode);
 int pnv_cxl_ioda_msi_setup(struct pci_dev *dev, unsigned int hwirq,
 			   unsigned int virq);

arch/powerpc/platforms/powernv/pci.c

···
 #include <asm/machdep.h>
 #include <asm/msi_bitmap.h>
 #include <asm/ppc-pci.h>
+#include <asm/pnv-pci.h>
 #include <asm/opal.h>
 #include <asm/iommu.h>
 #include <asm/tce.h>
···
 
 #include "powernv.h"
 #include "pci.h"
+
+int pnv_pci_get_slot_id(struct device_node *np, uint64_t *id)
+{
+	struct device_node *parent = np;
+	u32 bdfn;
+	u64 phbid;
+	int ret;
+
+	ret = of_property_read_u32(np, "reg", &bdfn);
+	if (ret)
+		return -ENXIO;
+
+	bdfn = ((bdfn & 0x00ffff00) >> 8);
+	while ((parent = of_get_parent(parent))) {
+		if (!PCI_DN(parent)) {
+			of_node_put(parent);
+			break;
+		}
+
+		if (!of_device_is_compatible(parent, "ibm,ioda2-phb")) {
+			of_node_put(parent);
+			continue;
+		}
+
+		ret = of_property_read_u64(parent, "ibm,opal-phbid", &phbid);
+		if (ret) {
+			of_node_put(parent);
+			return -ENXIO;
+		}
+
+		*id = PCI_SLOT_ID(phbid, bdfn);
+		return 0;
+	}
+
+	return -ENODEV;
+}
+EXPORT_SYMBOL_GPL(pnv_pci_get_slot_id);
 
 #ifdef CONFIG_PCI_MSI
 int pnv_setup_msi_irqs(struct pci_dev *pdev, int nvec, int type)