[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>

4 files changed, 37 insertions, 0 deletions

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