[PATCH v5 21/23] PCI/sysfs: Add __weak pci_legacy_has_sparse() helper

Krzysztof Wilczyński
2026-04-16T18:04:01Z

Currently, Alpha's sparse/dense legacy attribute handling is done via
pci_adjust_legacy_attr(), which updates dynamically allocated attributes
at runtime. The upcoming conversion to static attributes needs a way
to determine sparse support at visibility check time.

Add a __weak pci_legacy_has_sparse() that returns false by default.
Alpha overrides it to check has_sparse() on the bus host controller.

Signed-off-by: Krzysztof Wilczyński <kwilczynski@kernel.org>
---
arch/alpha/include/asm/pci.h | 2 ++
arch/alpha/kernel/pci-sysfs.c | 7 +++++++
drivers/pci/pci-sysfs.c | 6 ++++++
drivers/pci/pci.h | 4 ++++
4 files changed, 19 insertions(+)

diff --git a/arch/alpha/include/asm/pci.h b/arch/alpha/include/asm/pci.h
index ef19295f2e33..95de7ffd59e8 100644
--- a/arch/alpha/include/asm/pci.h
+++ b/arch/alpha/include/asm/pci.h
@@ -86,6 +86,8 @@ extern int pci_mmap_legacy_page_range(struct pci_bus *bus,
enum pci_mmap_state mmap_state);
extern void pci_adjust_legacy_attr(struct pci_bus *bus,
enum pci_mmap_state mmap_type);
+extern bool pci_legacy_has_sparse(struct pci_bus *bus,
+ enum pci_mmap_state type);
#define HAVE_PCI_LEGACY 1

extern const struct attribute_group pci_dev_resource_attr_group;
diff --git a/arch/alpha/kernel/pci-sysfs.c b/arch/alpha/kernel/pci-sysfs.c
index b986ff1e7a82..98f81bc73660 100644
--- a/arch/alpha/kernel/pci-sysfs.c
+++ b/arch/alpha/kernel/pci-sysfs.c
@@ -191,6 +191,13 @@ int pci_mmap_legacy_page_range(struct pci_bus *bus, struct vm_area_struct *vma,
return hose_mmap_page_range(hose, vma, mmap_type, sparse);
}

+bool pci_legacy_has_sparse(struct pci_bus *bus, enum pci_mmap_state type)
+{
+ struct pci_controller *hose = bus->sysdata;
+
+ return has_sparse(hose, type);
+}
+
/**
* pci_adjust_legacy_attr - adjustment of legacy file attributes
* @bus: bus to create files under
diff --git a/drivers/pci/pci-sysfs.c b/drivers/pci/pci-sysfs.c
index ad8ee192c94b..8d4ec862c326 100644
--- a/drivers/pci/pci-sysfs.c
+++ b/drivers/pci/pci-sysfs.c
@@ -1019,6 +1019,12 @@ static int pci_mmap_legacy_io(struct file *filp, struct kobject *kobj,
return pci_mmap_legacy_page_range(bus, vma, pci_mmap_io);
}

+bool __weak pci_legacy_has_sparse(struct pci_bus *bus,
+ enum pci_mmap_state type)
+{
+ return false;
+}
+
/**
* pci_adjust_legacy_attr - adjustment of legacy file attributes
* @b: bus to create files under
diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h
index 1bf165595583..f52caf7e4d13 100644
--- a/drivers/pci/pci.h
+++ b/drivers/pci/pci.h
@@ -390,6 +390,10 @@ static inline int pci_no_d1d2(struct pci_dev *dev)

}

+#ifdef HAVE_PCI_LEGACY
+bool pci_legacy_has_sparse(struct pci_bus *bus, enum pci_mmap_state type);
+#endif
+
#ifdef CONFIG_SYSFS
extern const struct attribute_group *pci_dev_groups[];
extern const struct attribute_group *pci_dev_attr_groups[];
--
2.53.0