[PATCH 19/20] PCI/sysfs: Convert legacy I/O and memory attributes to static definitions

Krzysztof Wilczyński
2026-04-10T07:15:55Z

Currently, legacy_io and legacy_mem are dynamically allocated and
created by pci_create_legacy_files(), with pci_adjust_legacy_attr()
updating the attributes at runtime on Alpha to rename them and shift
the size for sparse addressing.

Convert to four static const attributes (legacy_io, legacy_io_sparse,
legacy_mem, legacy_mem_sparse) with is_bin_visible() callbacks that
use pci_legacy_has_sparse() to select the appropriate variant per bus.
The sizes are compile-time constants and .size is set directly on
each attribute.

Register the groups in pcibus_groups[] under a HAVE_PCI_LEGACY guard
so the driver model handles creation and removal automatically.

Stub out pci_create_legacy_files() and pci_remove_legacy_files() as
the dynamic creation is no longer needed. Remove the __weak
pci_adjust_legacy_attr(), Alpha's override, and its declaration from
both Alpha and PowerPC asm/pci.h headers.

Signed-off-by: Krzysztof Wilczyński <kwilczynski@kernel.org>
---
arch/alpha/include/asm/pci.h | 4 +-
arch/alpha/kernel/pci-sysfs.c | 24 ----
arch/powerpc/include/asm/pci.h | 2 -
drivers/pci/pci-sysfs.c | 200 ++++++++++++++++++++-------------
4 files changed, 122 insertions(+), 108 deletions(-)

diff --git a/arch/alpha/include/asm/pci.h b/arch/alpha/include/asm/pci.h
index ef19295f2e33..ad5d1391e1fa 100644
--- a/arch/alpha/include/asm/pci.h
+++ b/arch/alpha/include/asm/pci.h
@@ -84,8 +84,8 @@ extern int pci_legacy_write(struct pci_bus *bus, loff_t port, u32 val,
extern int pci_mmap_legacy_page_range(struct pci_bus *bus,
struct vm_area_struct *vma,
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 2031a3b6972c..2db91169bf5a 100644
--- a/arch/alpha/kernel/pci-sysfs.c
+++ b/arch/alpha/kernel/pci-sysfs.c
@@ -197,30 +197,6 @@ bool pci_legacy_has_sparse(struct pci_bus *bus, enum pci_mmap_state type)
return has_sparse(hose, type);
}

-/**
- * pci_adjust_legacy_attr - adjustment of legacy file attributes
- * @bus: bus to create files under
- * @mmap_type: I/O port or memory
- *
- * Adjust file name and size for sparse mappings.
- */
-void pci_adjust_legacy_attr(struct pci_bus *bus, enum pci_mmap_state mmap_type)
-{
- struct pci_controller *hose = bus->sysdata;
-
- if (!has_sparse(hose, mmap_type))
- return;
-
- if (mmap_type == pci_mmap_mem) {
- bus->legacy_mem->attr.name = "legacy_mem_sparse";
- bus->legacy_mem->size <<= 5;
- } else {
- bus->legacy_io->attr.name = "legacy_io_sparse";
- bus->legacy_io->size <<= 5;
- }
- return;
-}
-
/* Legacy I/O bus read/write functions */
int pci_legacy_read(struct pci_bus *bus, loff_t port, u32 *val, size_t size)
{
diff --git a/arch/powerpc/include/asm/pci.h b/arch/powerpc/include/asm/pci.h
index 46a9c4491ed0..72f286e74786 100644
--- a/arch/powerpc/include/asm/pci.h
+++ b/arch/powerpc/include/asm/pci.h
@@ -82,8 +82,6 @@ extern int pci_legacy_write(struct pci_bus *bus, loff_t port, u32 val,
extern int pci_mmap_legacy_page_range(struct pci_bus *bus,
struct vm_area_struct *vma,
enum pci_mmap_state mmap_state);
-extern void pci_adjust_legacy_attr(struct pci_bus *bus,
- enum pci_mmap_state mmap_type);
#define HAVE_PCI_LEGACY 1

extern void pcibios_claim_one_bus(struct pci_bus *b);
diff --git a/drivers/pci/pci-sysfs.c b/drivers/pci/pci-sysfs.c
index fe079fb31dce..dc0bb0488317 100644
--- a/drivers/pci/pci-sysfs.c
+++ b/drivers/pci/pci-sysfs.c
@@ -702,11 +702,6 @@ static const struct attribute_group pcibus_group = {
.attrs = pcibus_attrs,
};

-const struct attribute_group *pcibus_groups[] = {
- &pcibus_group,
- NULL,
-};
-
static ssize_t boot_vga_show(struct device *dev, struct device_attribute *attr,
char *buf)
{
@@ -1025,91 +1020,136 @@ bool __weak pci_legacy_has_sparse(struct pci_bus *bus,
return false;
}

-/**
- * pci_adjust_legacy_attr - adjustment of legacy file attributes
- * @b: bus to create files under
- * @mmap_type: I/O port or memory
- *
- * Stub implementation. Can be overridden by arch if necessary.
- */
-void __weak pci_adjust_legacy_attr(struct pci_bus *b,
- enum pci_mmap_state mmap_type)
+static inline umode_t __pci_legacy_is_visible(struct kobject *kobj,
+ const struct bin_attribute *a,
+ enum pci_mmap_state type,
+ bool sparse)
{
+ struct pci_bus *bus = to_pci_bus(kobj_to_dev(kobj));
+
+ if (pci_legacy_has_sparse(bus, type) != sparse)
+ return 0;
+
+ return a->attr.mode;
}

-/**
- * pci_create_legacy_files - create legacy I/O port and memory files
- * @b: bus to create files under
- *
- * Some platforms allow access to legacy I/O port and ISA memory space on
- * a per-bus basis. This routine creates the files and ties them into
- * their associated read, write and mmap files from pci-sysfs.c
- *
- * On error unwind, but don't propagate the error to the caller
- * as it is ok to set up the PCI bus without these files.
- */
-void pci_create_legacy_files(struct pci_bus *b)
+static umode_t pci_legacy_io_is_visible(struct kobject *kobj,
+ const struct bin_attribute *a, int n)
{
- int error;
-
- if (!sysfs_initialized)
- return;
-
- b->legacy_io = kzalloc_objs(struct bin_attribute, 2, GFP_ATOMIC);
- if (!b->legacy_io)
- goto kzalloc_err;
-
- sysfs_bin_attr_init(b->legacy_io);
- b->legacy_io->attr.name = "legacy_io";
- b->legacy_io->size = 0xffff;
- b->legacy_io->attr.mode = 0600;
- b->legacy_io->read = pci_read_legacy_io;
- b->legacy_io->write = pci_write_legacy_io;
- /* See pci_create_attr() for motivation */
- b->legacy_io->llseek = pci_llseek_resource;
- b->legacy_io->mmap = pci_mmap_legacy_io;
- b->legacy_io->f_mapping = iomem_get_mapping;
- pci_adjust_legacy_attr(b, pci_mmap_io);
- error = device_create_bin_file(&b->dev, b->legacy_io);
- if (error)
- goto legacy_io_err;
-
- /* Allocated above after the legacy_io struct */
- b->legacy_mem = b->legacy_io + 1;
- sysfs_bin_attr_init(b->legacy_mem);
- b->legacy_mem->attr.name = "legacy_mem";
- b->legacy_mem->size = 1024*1024;
- b->legacy_mem->attr.mode = 0600;
- b->legacy_mem->mmap = pci_mmap_legacy_mem;
- /* See pci_create_attr() for motivation */
- b->legacy_mem->llseek = pci_llseek_resource;
- b->legacy_mem->f_mapping = iomem_get_mapping;
- pci_adjust_legacy_attr(b, pci_mmap_mem);
- error = device_create_bin_file(&b->dev, b->legacy_mem);
- if (error)
- goto legacy_mem_err;
-
- return;
-
-legacy_mem_err:
- device_remove_bin_file(&b->dev, b->legacy_io);
-legacy_io_err:
- kfree(b->legacy_io);
- b->legacy_io = NULL;
-kzalloc_err:
- dev_warn(&b->dev, "could not create legacy I/O port and ISA memory resources in sysfs\n");
+ return __pci_legacy_is_visible(kobj, a, pci_mmap_io, false);
}

-void pci_remove_legacy_files(struct pci_bus *b)
+static umode_t pci_legacy_io_sparse_is_visible(struct kobject *kobj,
+ const struct bin_attribute *a,
+ int n)
{
- if (b->legacy_io) {
- device_remove_bin_file(&b->dev, b->legacy_io);
- device_remove_bin_file(&b->dev, b->legacy_mem);
- kfree(b->legacy_io); /* both are allocated here */
- }
+ return __pci_legacy_is_visible(kobj, a, pci_mmap_io, true);
}
+
+static umode_t pci_legacy_mem_is_visible(struct kobject *kobj,
+ const struct bin_attribute *a, int n)
+{
+ return __pci_legacy_is_visible(kobj, a, pci_mmap_mem, false);
+}
+
+static umode_t pci_legacy_mem_sparse_is_visible(struct kobject *kobj,
+ const struct bin_attribute *a,
+ int n)
+{
+ return __pci_legacy_is_visible(kobj, a, pci_mmap_mem, true);
+}
+
+static const struct bin_attribute pci_legacy_io_attr = {
+ .attr = { .name = "legacy_io", .mode = 0600 },
+ .size = 0xffff,
+ .read = pci_read_legacy_io,
+ .write = pci_write_legacy_io,
+ .mmap = pci_mmap_legacy_io,
+ .llseek = pci_llseek_resource,
+ .f_mapping = iomem_get_mapping,
+};
+
+static const struct bin_attribute pci_legacy_io_sparse_attr = {
+ .attr = { .name = "legacy_io_sparse", .mode = 0600 },
+ .size = 0xffff << 5,
+ .read = pci_read_legacy_io,
+ .write = pci_write_legacy_io,
+ .mmap = pci_mmap_legacy_io,
+ .llseek = pci_llseek_resource,
+ .f_mapping = iomem_get_mapping,
+};
+
+static const struct bin_attribute pci_legacy_mem_attr = {
+ .attr = { .name = "legacy_mem", .mode = 0600 },
+ .size = 0x100000,
+ .mmap = pci_mmap_legacy_mem,
+ .llseek = pci_llseek_resource,
+ .f_mapping = iomem_get_mapping,
+};
+
+static const struct bin_attribute pci_legacy_mem_sparse_attr = {
+ .attr = { .name = "legacy_mem_sparse", .mode = 0600 },
+ .size = 0x100000 << 5,
+ .mmap = pci_mmap_legacy_mem,
+ .llseek = pci_llseek_resource,
+ .f_mapping = iomem_get_mapping,
+};
+
+static const struct bin_attribute *const pci_legacy_io_attrs[] = {
+ &pci_legacy_io_attr,
+ NULL,
+};
+
+static const struct bin_attribute *const pci_legacy_io_sparse_attrs[] = {
+ &pci_legacy_io_sparse_attr,
+ NULL,
+};
+
+static const struct bin_attribute *const pci_legacy_mem_attrs[] = {
+ &pci_legacy_mem_attr,
+ NULL,
+};
+
+static const struct bin_attribute *const pci_legacy_mem_sparse_attrs[] = {
+ &pci_legacy_mem_sparse_attr,
+ NULL,
+};
+
+static const struct attribute_group pci_legacy_io_group = {
+ .bin_attrs = pci_legacy_io_attrs,
+ .is_bin_visible = pci_legacy_io_is_visible,
+};
+
+static const struct attribute_group pci_legacy_io_sparse_group = {
+ .bin_attrs = pci_legacy_io_sparse_attrs,
+ .is_bin_visible = pci_legacy_io_sparse_is_visible,
+};
+
+static const struct attribute_group pci_legacy_mem_group = {
+ .bin_attrs = pci_legacy_mem_attrs,
+ .is_bin_visible = pci_legacy_mem_is_visible,
+};
+
+static const struct attribute_group pci_legacy_mem_sparse_group = {
+ .bin_attrs = pci_legacy_mem_sparse_attrs,
+ .is_bin_visible = pci_legacy_mem_sparse_is_visible,
+};
+
+void pci_create_legacy_files(struct pci_bus *b) { }
+void pci_remove_legacy_files(struct pci_bus *b) { }
#endif /* HAVE_PCI_LEGACY */

+const struct attribute_group *pcibus_groups[] = {
+ &pcibus_group,
+#ifdef HAVE_PCI_LEGACY
+ &pci_legacy_io_group,
+ &pci_legacy_io_sparse_group,
+ &pci_legacy_mem_group,
+ &pci_legacy_mem_sparse_group,
+#endif
+ NULL,
+};
+
#if defined(HAVE_PCI_MMAP) || defined(ARCH_GENERIC_PCI_MMAP_RESOURCE)
/**
* pci_mmap_resource - map a PCI resource into user memory space
--
2.53.0