[SRU][F][PATCH 5/12] s390/pci: define kernel parameters for PCI multifunction

[frank.heimes at canonical.com]

From: Pierre Morel <pmorel at linux.ibm.com>

BugLink: https://bugs.launchpad.net/bugs/1874056

Using PCI multifunctions in S390 is a new feature we may want
to ignore to continue provide the same topology as in the past
to userland even if the configuration supports exposing the
topology of a multi-Function device.

A new boolean parameters allows to overwrite the kernel
pci configuration:

- pci=norid when on, disallow the use a new firmware field,
  RID, which provides the PCI <bus>:<device>.<function> part
  of the PCI address.

To be used in the following patches and satisfy the checkpatch.pl
the variable is exposed in pci.h

Signed-off-by: Pierre Morel <pmorel at linux.ibm.com>
Reviewed-by: Niklas Schnelle <schnelle at linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor at linux.ibm.com>
(backported from commit 6cf17f9a67c124aa4739b79709008d942635b975)
Signed-off-by: Frank Heimes <frank.heimes at canonical.com>
---
 arch/s390/include/asm/pci.h | 1 +
 arch/s390/pci/pci.c         | 6 ++++++
 2 files changed, 7 insertions(+)

diff --git a/arch/s390/include/asm/pci.h b/arch/s390/include/asm/pci.h
index 3ee949a83778..5dfcb8db5828 100644
--- a/arch/s390/include/asm/pci.h
+++ b/arch/s390/include/asm/pci.h
@@ -171,6 +171,7 @@ static inline bool zdev_enabled(struct zpci_dev *zdev)
 
 extern const struct attribute_group *zpci_attr_groups[];
 extern unsigned int s390_pci_force_floating __initdata;
+extern unsigned int s390_pci_no_rid;
 
 /* -----------------------------------------------------------------------------
   Prototypes
diff --git a/arch/s390/pci/pci.c b/arch/s390/pci/pci.c
index c0f80e896d7b..1675fef70690 100644
--- a/arch/s390/pci/pci.c
+++ b/arch/s390/pci/pci.c
@@ -47,6 +47,8 @@ static unsigned int zpci_num_domains_allocated;
 	min(((unsigned long) ZPCI_NR_DEVICES * PCI_BAR_COUNT / 2),	\
 	    ZPCI_IOMAP_MAX_ENTRIES)
 
+unsigned int s390_pci_no_rid;
+
 static DEFINE_SPINLOCK(zpci_iomap_lock);
 static unsigned long *zpci_iomap_bitmap;
 struct zpci_iomap_entry *zpci_iomap_start;
@@ -886,6 +888,10 @@ char * __init pcibios_setup(char *str)
 		s390_pci_force_floating = 1;
 		return NULL;
 	}
+	if (!strcmp(str, "norid")) {
+		s390_pci_no_rid = 1;
+		return NULL;
+	}
 	return str;
 }
 
-- 
2.25.1