[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>

10 files changed, 78 insertions, 43 deletions

diff --git a/src/arch/x86/core/pcidirect.c b/src/arch/x86/core/pcidirect.c
index 9b8226fea..88db90499 100644
--- a/src/arch/x86/core/pcidirect.c
+++ b/src/arch/x86/core/pcidirect.c
@@ -45,7 +45,7 @@ void pcidirect_prepare ( struct pci_device *pci, int where ) {
 	       PCIDIRECT_CONFIG_ADDRESS );
 }
 
-PROVIDE_PCIAPI_INLINE ( direct, pci_num_bus );
+PROVIDE_PCIAPI_INLINE ( direct, pci_discover );
 PROVIDE_PCIAPI_INLINE ( direct, pci_read_config_byte );
 PROVIDE_PCIAPI_INLINE ( direct, pci_read_config_word );
 PROVIDE_PCIAPI_INLINE ( direct, pci_read_config_dword );
diff --git a/src/arch/x86/include/ipxe/pcidirect.h b/src/arch/x86/include/ipxe/pcidirect.h
index decdc8100..394edb2b8 100644
--- a/src/arch/x86/include/ipxe/pcidirect.h
+++ b/src/arch/x86/include/ipxe/pcidirect.h
@@ -26,14 +26,18 @@ struct pci_device;
 extern void pcidirect_prepare ( struct pci_device *pci, int where );
 
 /**
- * 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 ( direct, pci_num_bus ) ( void ) {
+static inline __always_inline void
+PCIAPI_INLINE ( direct, pci_discover ) ( uint32_t busdevfn __unused,
+					 struct pci_range *range ) {
+
 	/* Scan first bus and rely on bridge detection to find higher buses */
-	return 1;
+	range->start = PCI_BUSDEVFN ( 0, 0, 0, 0 );
+	range->count = PCI_BUSDEVFN ( 0, 1, 0, 0 );
 }
 
 /**
diff --git a/src/arch/x86/interface/pcbios/pcibios.c b/src/arch/x86/interface/pcbios/pcibios.c
index bf812f77f..cf818630a 100644
--- a/src/arch/x86/interface/pcbios/pcibios.c
+++ b/src/arch/x86/interface/pcbios/pcibios.c
@@ -34,11 +34,13 @@ FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
  */
 
 /**
- * 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 int pcibios_num_bus ( void ) {
+static void pcibios_discover ( uint32_t busdevfn __unused,
+			       struct pci_range *range ) {
 	int discard_a, discard_D;
 	uint8_t max_bus;
 
@@ -57,7 +59,9 @@ static int pcibios_num_bus ( void ) {
 				 "D" ( 0 )
 			       : "ebx", "edx" );
 
-	return ( max_bus + 1 );
+	/* Populate range */
+	range->start = PCI_BUSDEVFN ( 0, 0, 0, 0 );
+	range->count = PCI_BUSDEVFN ( 0, ( max_bus + 1 ), 0, 0 );
 }
 
 /**
@@ -114,7 +118,7 @@ int pcibios_write ( struct pci_device *pci, uint32_t command, uint32_t value ){
 	return ( status >> 8 );
 }
 
-PROVIDE_PCIAPI ( pcbios, pci_num_bus, pcibios_num_bus );
+PROVIDE_PCIAPI ( pcbios, pci_discover, pcibios_discover );
 PROVIDE_PCIAPI_INLINE ( pcbios, pci_read_config_byte );
 PROVIDE_PCIAPI_INLINE ( pcbios, pci_read_config_word );
 PROVIDE_PCIAPI_INLINE ( pcbios, pci_read_config_dword );
diff --git a/src/drivers/bus/pci.c b/src/drivers/bus/pci.c
index c5deb08f6..7953aaedd 100644
--- a/src/drivers/bus/pci.c
+++ b/src/drivers/bus/pci.c
@@ -233,18 +233,23 @@ int pci_read_config ( struct pci_device *pci ) {
  * @ret rc		Return status code
  */
 int pci_find_next ( struct pci_device *pci, uint32_t *busdevfn ) {
-	static unsigned int end;
-	unsigned int sub_end;
+	static struct pci_range range;
 	uint8_t hdrtype;
 	uint8_t sub;
+	uint32_t end;
+	unsigned int count;
 	int rc;
 
-	/* Determine number of PCI buses */
-	if ( ! end )
-		end = PCI_BUSDEVFN ( 0, pci_num_bus(), 0, 0 );
-
 	/* Find next PCI device, if any */
-	for ( ; *busdevfn < end ; (*busdevfn)++ ) {
+	do {
+		/* Find next PCI bus:dev.fn address range, if necessary */
+		if ( ( *busdevfn - range.start ) >= range.count ) {
+			pci_discover ( *busdevfn, &range );
+			if ( *busdevfn < range.start )
+				*busdevfn = range.start;
+			if ( ( *busdevfn - range.start ) >= range.count )
+				break;
+		}
 
 		/* Check for PCI device existence */
 		memset ( pci, 0, sizeof ( *pci ) );
@@ -252,24 +257,27 @@ int pci_find_next ( struct pci_device *pci, uint32_t *busdevfn ) {
 		if ( ( rc = pci_read_config ( pci ) ) != 0 )
 			continue;
 
-		/* If device is a bridge, expand the number of PCI
-		 * buses as needed.
+		/* If device is a bridge, expand the PCI bus:dev.fn
+		 * address range as needed.
 		 */
 		pci_read_config_byte ( pci, PCI_HEADER_TYPE, &hdrtype );
 		hdrtype &= PCI_HEADER_TYPE_MASK;
 		if ( hdrtype == PCI_HEADER_TYPE_BRIDGE ) {
 			pci_read_config_byte ( pci, PCI_SUBORDINATE, &sub );
-			sub_end = PCI_BUSDEVFN ( 0, ( sub + 1 ), 0, 0 );
-			if ( end < sub_end ) {
+			end = PCI_BUSDEVFN ( PCI_SEG ( *busdevfn ),
+					     ( sub + 1 ), 0, 0 );
+			count = ( end - range.start );
+			if ( count > range.count ) {
 				DBGC ( pci, PCI_FMT " found subordinate bus "
 				       "%#02x\n", PCI_ARGS ( pci ), sub );
-				end = sub_end;
+				range.count = count;
 			}
 		}
 
 		/* Return this device */
 		return 0;
-	}
+
+	} while ( ++(*busdevfn) );
 
 	return -ENODEV;
 }
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
diff --git a/src/interface/efi/efi_pci.c b/src/interface/efi/efi_pci.c
index fda4aba0e..19e341707 100644
--- a/src/interface/efi/efi_pci.c
+++ b/src/interface/efi/efi_pci.c
@@ -362,7 +362,7 @@ void * efipci_ioremap ( struct pci_device *pci, unsigned long bus_addr,
 	return ioremap ( bus_addr, len );
 }
 
-PROVIDE_PCIAPI_INLINE ( efi, pci_num_bus );
+PROVIDE_PCIAPI_INLINE ( efi, pci_discover );
 PROVIDE_PCIAPI_INLINE ( efi, pci_read_config_byte );
 PROVIDE_PCIAPI_INLINE ( efi, pci_read_config_word );
 PROVIDE_PCIAPI_INLINE ( efi, pci_read_config_dword );
diff --git a/src/interface/linux/linux_pci.c b/src/interface/linux/linux_pci.c
index e3c0daa32..300844737 100644
--- a/src/interface/linux/linux_pci.c
+++ b/src/interface/linux/linux_pci.c
@@ -188,7 +188,7 @@ int linux_pci_write ( struct pci_device *pci, unsigned long where,
 	return rc;
 }
 
-PROVIDE_PCIAPI_INLINE ( linux, pci_num_bus );
+PROVIDE_PCIAPI_INLINE ( linux, pci_discover );
 PROVIDE_PCIAPI_INLINE ( linux, pci_read_config_byte );
 PROVIDE_PCIAPI_INLINE ( linux, pci_read_config_word );
 PROVIDE_PCIAPI_INLINE ( linux, pci_read_config_dword );