[pci] Generalise pci_num_bus() to pci_discover()

Allow pci_find_next() to discover devices beyond the first PCI
segment, by generalising pci_num_bus() (which implicitly assumes that
there is only a single PCI segment) with pci_discover() (which has the
ability to return an arbitrary contiguous chunk of PCI bus:dev.fn
address space).

Signed-off-by: Michael Brown <mcb30@ipxe.org>

4 files changed, 36 insertions, 17 deletions

diff --git a/src/include/ipxe/efi/efi_pci_api.h b/src/include/ipxe/efi/efi_pci_api.h
index 887d5ee14..cf5e1d020 100644
--- a/src/include/ipxe/efi/efi_pci_api.h
+++ b/src/include/ipxe/efi/efi_pci_api.h
@@ -33,14 +33,17 @@ extern int efipci_write ( struct pci_device *pci, unsigned long location,
 			  unsigned long value );
 
 /**
- * Determine number of PCI buses within system
+ * Find next PCI bus:dev.fn address range in system
  *
- * @ret num_bus		Number of buses
+ * @v busdevfn		Starting PCI bus:dev.fn address
+ * @v range		PCI bus:dev.fn address range to fill in
  */
-static inline __always_inline int
-PCIAPI_INLINE ( efi, pci_num_bus ) ( void ) {
+static inline __always_inline void
+PCIAPI_INLINE ( efi, pci_discover ) ( uint32_t busdevfn __unused,
+				      struct pci_range *range ) {
+
 	/* EFI does not want us to scan the PCI bus ourselves */
-	return 0;
+	range->count = 0;
 }
 
 /**
diff --git a/src/include/ipxe/linux/linux_pci.h b/src/include/ipxe/linux/linux_pci.h
index de42f766b..ec6ff8b1c 100644
--- a/src/include/ipxe/linux/linux_pci.h
+++ b/src/include/ipxe/linux/linux_pci.h
@@ -23,14 +23,18 @@ extern int linux_pci_write ( struct pci_device *pci, unsigned long where,
 			     unsigned long value, size_t len );
 
 /**
- * Determine number of PCI buses within system
+ * Find next PCI bus:dev.fn address range in system
  *
- * @ret num_bus		Number of buses
+ * @v busdevfn		Starting PCI bus:dev.fn address
+ * @v range		PCI bus:dev.fn address range to fill in
  */
-static inline __always_inline int
-PCIAPI_INLINE ( linux, pci_num_bus ) ( void ) {
-	/* Assume all buses may exist */
-	return 0x100;
+static inline __always_inline void
+PCIAPI_INLINE ( linux, pci_discover ) ( uint32_t busdevfn __unused,
+					struct pci_range *range ) {
+
+	/* Assume all buses in segment 0 may exist */
+	range->start = PCI_BUSDEVFN ( 0, 0, 0, 0 );
+	range->count = PCI_BUSDEVFN ( 1, 0, 0, 0 );
 }
 
 /**
diff --git a/src/include/ipxe/pci.h b/src/include/ipxe/pci.h
index bd123679a..c91baaddd 100644
--- a/src/include/ipxe/pci.h
+++ b/src/include/ipxe/pci.h
@@ -262,9 +262,6 @@ struct pci_driver {
 #define PCI_BUS( busdevfn )		( ( (busdevfn) >> 8 ) & 0xff )
 #define PCI_SLOT( busdevfn )		( ( (busdevfn) >> 3 ) & 0x1f )
 #define PCI_FUNC( busdevfn )		( ( (busdevfn) >> 0 ) & 0x07 )
-#define PCI_BUSDEVFN( segment, bus, slot, func )			\
-	( ( (segment) << 16 ) | ( (bus) << 8 ) |			\
-	  ( (slot) << 3 ) | ( (func) << 0 ) )
 #define PCI_FIRST_FUNC( busdevfn )	( (busdevfn) & ~0x07 )
 #define PCI_LAST_FUNC( busdevfn )	( (busdevfn) | 0x07 )
 
diff --git a/src/include/ipxe/pci_io.h b/src/include/ipxe/pci_io.h
index 2dcdd9b28..91359cec8 100644
--- a/src/include/ipxe/pci_io.h
+++ b/src/include/ipxe/pci_io.h
@@ -14,6 +14,20 @@ FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
 #include <ipxe/iomap.h>
 #include <config/ioapi.h>
 
+struct pci_device;
+
+/** A PCI bus:dev.fn address range */
+struct pci_range {
+	/** Starting bus:dev.fn address */
+	uint32_t start;
+	/** Number of bus:dev.fn addresses within this range */
+	unsigned int count;
+};
+
+#define PCI_BUSDEVFN( segment, bus, slot, func )			\
+	( ( (segment) << 16 ) | ( (bus) << 8 ) |			\
+	  ( (slot) << 3 ) | ( (func) << 0 ) )
+
 /**
  * Calculate static inline PCI I/O API function name
  *
@@ -51,11 +65,12 @@ FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
 #include <bits/pci_io.h>
 
 /**
- * Determine number of PCI buses within system
+ * Find next PCI bus:dev.fn address range in system
  *
- * @ret num_bus		Number of buses
+ * @v busdevfn		Starting PCI bus:dev.fn address
+ * @v range		PCI bus:dev.fn address range to fill in
  */
-int pci_num_bus ( void );
+void pci_discover ( uint32_t busdevfn, struct pci_range *range );
 
 /**
  * Read byte from PCI configuration space