[pci] Separate permission to probe buses from bus:dev.fn range discovery

The UEFI device model requires us to not probe the PCI bus directly,
but instead to wait to be offered the opportunity to drive devices via
our driver service binding handle.

We currently inhibit PCI bus probing by having pci_discover() return
an empty range when using the EFI PCI I/O API.  This has the unwanted
side effect that scanning the bus manually using the "pciscan" command
will also fail to discover any devices.

Separate out the concept of being allowed to probe PCI buses from the
mechanism for discovering PCI bus:dev.fn address ranges, so that this
limitation may be removed.

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

14 files changed, 77 insertions, 0 deletions

diff --git a/src/arch/x86/core/pcidirect.c b/src/arch/x86/core/pcidirect.c
index f4659a1ac..90d4623b3 100644
--- a/src/arch/x86/core/pcidirect.c
+++ b/src/arch/x86/core/pcidirect.c
@@ -45,6 +45,7 @@ void pcidirect_prepare ( struct pci_device *pci, int where ) {
 	       PCIDIRECT_CONFIG_ADDRESS );
 }
 
+PROVIDE_PCIAPI_INLINE ( direct, pci_can_probe );
 PROVIDE_PCIAPI_INLINE ( direct, pci_discover );
 PROVIDE_PCIAPI_INLINE ( direct, pci_read_config_byte );
 PROVIDE_PCIAPI_INLINE ( direct, pci_read_config_word );
diff --git a/src/arch/x86/include/ipxe/pcibios.h b/src/arch/x86/include/ipxe/pcibios.h
index 3caea1cfe..ef9585654 100644
--- a/src/arch/x86/include/ipxe/pcibios.h
+++ b/src/arch/x86/include/ipxe/pcibios.h
@@ -33,6 +33,16 @@ extern int pcibios_write ( struct pci_device *pci, uint32_t command,
 			   uint32_t value );
 
 /**
+ * Check if PCI bus probing is allowed
+ *
+ * @ret ok		Bus probing is allowed
+ */
+static inline __always_inline int
+PCIAPI_INLINE ( pcbios, pci_can_probe ) ( void ) {
+	return 1;
+}
+
+/**
  * Read byte from PCI configuration space via PCI BIOS
  *
  * @v pci	PCI device
diff --git a/src/arch/x86/include/ipxe/pcicloud.h b/src/arch/x86/include/ipxe/pcicloud.h
index 52268908c..1feef56cb 100644
--- a/src/arch/x86/include/ipxe/pcicloud.h
+++ b/src/arch/x86/include/ipxe/pcicloud.h
@@ -15,4 +15,14 @@ FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
 #define PCIAPI_PREFIX_cloud __cloud_
 #endif
 
+/**
+ * Check if PCI bus probing is allowed
+ *
+ * @ret ok		Bus probing is allowed
+ */
+static inline __always_inline int
+PCIAPI_INLINE ( cloud, pci_can_probe ) ( void ) {
+	return 1;
+}
+
 #endif /* _IPXE_PCICLOUD_H */
diff --git a/src/arch/x86/include/ipxe/pcidirect.h b/src/arch/x86/include/ipxe/pcidirect.h
index 98c6a2bbb..999b52763 100644
--- a/src/arch/x86/include/ipxe/pcidirect.h
+++ b/src/arch/x86/include/ipxe/pcidirect.h
@@ -26,6 +26,16 @@ struct pci_device;
 extern void pcidirect_prepare ( struct pci_device *pci, int where );
 
 /**
+ * Check if PCI bus probing is allowed
+ *
+ * @ret ok		Bus probing is allowed
+ */
+static inline __always_inline int
+PCIAPI_INLINE ( direct, pci_can_probe ) ( void ) {
+	return 1;
+}
+
+/**
  * Find next PCI bus:dev.fn address range in system
  *
  * @v busdevfn		Starting PCI bus:dev.fn address
diff --git a/src/arch/x86/interface/pcbios/pcibios.c b/src/arch/x86/interface/pcbios/pcibios.c
index 7b7a769e3..ebe40ba7d 100644
--- a/src/arch/x86/interface/pcbios/pcibios.c
+++ b/src/arch/x86/interface/pcbios/pcibios.c
@@ -120,6 +120,7 @@ int pcibios_write ( struct pci_device *pci, uint32_t command, uint32_t value ){
 	return ( status >> 8 );
 }
 
+PROVIDE_PCIAPI_INLINE ( pcbios, pci_can_probe );
 PROVIDE_PCIAPI ( pcbios, pci_discover, pcibios_discover );
 PROVIDE_PCIAPI_INLINE ( pcbios, pci_read_config_byte );
 PROVIDE_PCIAPI_INLINE ( pcbios, pci_read_config_word );
diff --git a/src/arch/x86/interface/pcbios/pcicloud.c b/src/arch/x86/interface/pcbios/pcicloud.c
index 98ba38b31..f7d4a2da1 100644
--- a/src/arch/x86/interface/pcbios/pcicloud.c
+++ b/src/arch/x86/interface/pcbios/pcicloud.c
@@ -148,6 +148,7 @@ static void * pcicloud_ioremap ( struct pci_device *pci,
 	return pcicloud->pci_ioremap ( pci, bus_addr, len );
 }
 
+PROVIDE_PCIAPI_INLINE ( cloud, pci_can_probe );
 PROVIDE_PCIAPI ( cloud, pci_discover, pcicloud_discover );
 PROVIDE_PCIAPI ( cloud, pci_read_config_byte, pcicloud_read_config_byte );
 PROVIDE_PCIAPI ( cloud, pci_read_config_word, pcicloud_read_config_word );
diff --git a/src/drivers/bus/ecam.c b/src/drivers/bus/ecam.c
index 5e3debddd..cde5952b8 100644
--- a/src/drivers/bus/ecam.c
+++ b/src/drivers/bus/ecam.c
@@ -276,6 +276,7 @@ int ecam_write ( struct pci_device *pci, unsigned int location,
 	return 0;
 }
 
+PROVIDE_PCIAPI_INLINE ( ecam, pci_can_probe );
 PROVIDE_PCIAPI ( ecam, pci_discover, ecam_discover );
 PROVIDE_PCIAPI_INLINE ( ecam, pci_read_config_byte );
 PROVIDE_PCIAPI_INLINE ( ecam, pci_read_config_word );
diff --git a/src/drivers/bus/pci.c b/src/drivers/bus/pci.c
index 92b389641..05c9a5c26 100644
--- a/src/drivers/bus/pci.c
+++ b/src/drivers/bus/pci.c
@@ -361,6 +361,10 @@ static int pcibus_probe ( struct root_device *rootdev ) {
 	uint32_t busdevfn = 0;
 	int rc;
 
+	/* Skip automatic probing if prohibited */
+	if ( ! pci_can_probe() )
+		return 0;
+
 	do {
 		/* Allocate struct pci_device */
 		if ( ! pci )
diff --git a/src/include/ipxe/ecam.h b/src/include/ipxe/ecam.h
index ff08aee5a..f656083f7 100644
--- a/src/include/ipxe/ecam.h
+++ b/src/include/ipxe/ecam.h
@@ -54,6 +54,16 @@ struct ecam_mapping {
 	int rc;
 };
 
+/**
+ * Check if PCI bus probing is allowed
+ *
+ * @ret ok		Bus probing is allowed
+ */
+static inline __always_inline int
+PCIAPI_INLINE ( ecam, pci_can_probe ) ( void ) {
+	return 1;
+}
+
 extern struct pci_api ecam_api;
 
 #endif /* _IPXE_ECAM_H */
diff --git a/src/include/ipxe/efi/efi_pci_api.h b/src/include/ipxe/efi/efi_pci_api.h
index cf5e1d020..0c4c1b72c 100644
--- a/src/include/ipxe/efi/efi_pci_api.h
+++ b/src/include/ipxe/efi/efi_pci_api.h
@@ -33,6 +33,16 @@ extern int efipci_write ( struct pci_device *pci, unsigned long location,
 			  unsigned long value );
 
 /**
+ * Check if PCI bus probing is allowed
+ *
+ * @ret ok		Bus probing is allowed
+ */
+static inline __always_inline int
+PCIAPI_INLINE ( efi, pci_can_probe ) ( void ) {
+	return 0;
+}
+
+/**
  * Find next PCI bus:dev.fn address range in system
  *
  * @v busdevfn		Starting PCI bus:dev.fn address
diff --git a/src/include/ipxe/linux/linux_pci.h b/src/include/ipxe/linux/linux_pci.h
index ec6ff8b1c..2b19e13c3 100644
--- a/src/include/ipxe/linux/linux_pci.h
+++ b/src/include/ipxe/linux/linux_pci.h
@@ -23,6 +23,16 @@ extern int linux_pci_write ( struct pci_device *pci, unsigned long where,
 			     unsigned long value, size_t len );
 
 /**
+ * Check if PCI bus probing is allowed
+ *
+ * @ret ok		Bus probing is allowed
+ */
+static inline __always_inline int
+PCIAPI_INLINE ( linux, pci_can_probe ) ( void ) {
+	return 1;
+}
+
+/**
  * Find next PCI bus:dev.fn address range in system
  *
  * @v busdevfn		Starting PCI bus:dev.fn address
diff --git a/src/include/ipxe/pci_io.h b/src/include/ipxe/pci_io.h
index 4c035b18b..322fdbb24 100644
--- a/src/include/ipxe/pci_io.h
+++ b/src/include/ipxe/pci_io.h
@@ -67,6 +67,13 @@ struct pci_range {
 #include <bits/pci_io.h>
 
 /**
+ * Check if PCI bus probing is allowed
+ *
+ * @ret ok		Bus probing is allowed
+ */
+int pci_can_probe ( void );
+
+/**
  * Find next PCI bus:dev.fn address range in system
  *
  * @v busdevfn		Starting PCI bus:dev.fn address
diff --git a/src/interface/efi/efi_pci.c b/src/interface/efi/efi_pci.c
index e2eeeb344..61071d8a4 100644
--- a/src/interface/efi/efi_pci.c
+++ b/src/interface/efi/efi_pci.c
@@ -362,6 +362,7 @@ void * efipci_ioremap ( struct pci_device *pci, unsigned long bus_addr,
 	return ioremap ( bus_addr, len );
 }
 
+PROVIDE_PCIAPI_INLINE ( efi, pci_can_probe );
 PROVIDE_PCIAPI_INLINE ( efi, pci_discover );
 PROVIDE_PCIAPI_INLINE ( efi, pci_read_config_byte );
 PROVIDE_PCIAPI_INLINE ( efi, pci_read_config_word );
diff --git a/src/interface/linux/linux_pci.c b/src/interface/linux/linux_pci.c
index 300844737..a3a0828c1 100644
--- a/src/interface/linux/linux_pci.c
+++ b/src/interface/linux/linux_pci.c
@@ -188,6 +188,7 @@ int linux_pci_write ( struct pci_device *pci, unsigned long where,
 	return rc;
 }
 
+PROVIDE_PCIAPI_INLINE ( linux, pci_can_probe );
 PROVIDE_PCIAPI_INLINE ( linux, pci_discover );
 PROVIDE_PCIAPI_INLINE ( linux, pci_read_config_byte );
 PROVIDE_PCIAPI_INLINE ( linux, pci_read_config_word );