PCI/sysfs: Convert legacy I/O and memory attributes to static definitions

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>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Tested-by: Shivaprasad G Bhat <sbhat@linux.ibm.com>
Link: https://patch.msgid.link/20260508043543.217179-23-kwilczynski@kernel.org

arch/alpha/include/asm/pci.h

@@ -84,8 +84,6 @@ 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);
 extern bool pci_legacy_has_sparse(struct pci_bus *bus,
 				  enum pci_mmap_state type);
 #define HAVE_PCI_LEGACY	1

arch/alpha/kernel/pci-sysfs.c

@@ -191,30 +191,6 @@ 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)
 {
@@ -291,9 +267,9 @@ static inline enum pci_mmap_state pci_bar_mmap_type(struct pci_dev *pdev,
 	return pci_resource_is_mem(pdev, bar) ? pci_mmap_mem : pci_mmap_io;
 }
 
-static inline umode_t __pci_dev_resource_is_visible(struct kobject *kobj,
-						    const struct bin_attribute *a,
-						    int bar)
+static inline umode_t __pci_resource_attr_is_visible(struct kobject *kobj,
+						     const struct bin_attribute *a,
+						     int bar)
 {
 	struct pci_dev *pdev = to_pci_dev(kobj_to_dev(kobj));
 
@@ -313,7 +289,7 @@ static umode_t pci_dev_resource_is_visible(struct kobject *kobj,
 	if (has_sparse(hose, pci_bar_mmap_type(pdev, bar)))
 		return 0;
 
-	return __pci_dev_resource_is_visible(kobj, a, bar);
+	return __pci_resource_attr_is_visible(kobj, a, bar);
 }
 
 static umode_t pci_dev_resource_sparse_is_visible(struct kobject *kobj,
@@ -330,7 +306,7 @@ static umode_t pci_dev_resource_sparse_is_visible(struct kobject *kobj,
 	if (type == pci_mmap_mem && !sparse_mem_mmap_fits(pdev, bar))
 		return 0;
 
-	return __pci_dev_resource_is_visible(kobj, a, bar);
+	return __pci_resource_attr_is_visible(kobj, a, bar);
 }
 
 static umode_t pci_dev_resource_dense_is_visible(struct kobject *kobj,
@@ -346,14 +322,14 @@ static umode_t pci_dev_resource_dense_is_visible(struct kobject *kobj,
 		return 0;
 
 	if (type == pci_mmap_mem && !sparse_mem_mmap_fits(pdev, bar))
-		return __pci_dev_resource_is_visible(kobj, a, bar);
+		return __pci_resource_attr_is_visible(kobj, a, bar);
 
 	dense_base = (type == pci_mmap_mem) ? hose->dense_mem_base :
 					      hose->dense_io_base;
 	if (!dense_base)
 		return 0;
 
-	return __pci_dev_resource_is_visible(kobj, a, bar);
+	return __pci_resource_attr_is_visible(kobj, a, bar);
 }
 
 static inline size_t __pci_dev_resource_bin_size(struct kobject *kobj,

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);

drivers/pci/pci-sysfs.c

@@ -676,11 +676,6 @@ 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)
 {
@@ -879,19 +874,6 @@ static const struct attribute_group pci_dev_config_attr_group = {
 	.bin_size = pci_dev_config_attr_bin_size,
 };
 
-/*
- * llseek operation for mmappable PCI resources.
- * May be left unused if the arch doesn't provide them.
- */
-static __maybe_unused loff_t
-pci_llseek_resource_legacy(struct file *filep,
-			   struct kobject *kobj __always_unused,
-			   const struct bin_attribute *attr,
-			   loff_t offset, int whence)
-{
-	return fixed_size_llseek(filep, offset, whence, attr->size);
-}
-
 #ifdef HAVE_PCI_LEGACY
 /**
  * pci_read_legacy_io - read byte(s) from legacy I/O port space
@@ -989,91 +971,144 @@ 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 = PCI_LEGACY_IO_SIZE;
-	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_legacy;
-	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 = PCI_LEGACY_MEM_SIZE;
-	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_legacy;
-	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 loff_t pci_llseek_resource_legacy(struct file *filep,
+					 struct kobject *kobj __always_unused,
+					 const struct bin_attribute *attr,
+					 loff_t offset, int whence)
+{
+	return fixed_size_llseek(filep, offset, whence, attr->size);
+}
+
+static const struct bin_attribute pci_legacy_io_attr = {
+	.attr = { .name = "legacy_io", .mode = 0600 },
+	.size = PCI_LEGACY_IO_SIZE,
+	.read = pci_read_legacy_io,
+	.write = pci_write_legacy_io,
+	.mmap = pci_mmap_legacy_io,
+	.llseek = pci_llseek_resource_legacy,
+	.f_mapping = iomem_get_mapping,
+};
+
+static const struct bin_attribute pci_legacy_io_sparse_attr = {
+	.attr = { .name = "legacy_io_sparse", .mode = 0600 },
+	.size = PCI_LEGACY_IO_SIZE << 5,
+	.read = pci_read_legacy_io,
+	.write = pci_write_legacy_io,
+	.mmap = pci_mmap_legacy_io,
+	.llseek = pci_llseek_resource_legacy,
+	.f_mapping = iomem_get_mapping,
+};
+
+static const struct bin_attribute pci_legacy_mem_attr = {
+	.attr = { .name = "legacy_mem", .mode = 0600 },
+	.size = PCI_LEGACY_MEM_SIZE,
+	.mmap = pci_mmap_legacy_mem,
+	.llseek = pci_llseek_resource_legacy,
+	.f_mapping = iomem_get_mapping,
+};
+
+static const struct bin_attribute pci_legacy_mem_sparse_attr = {
+	.attr = { .name = "legacy_mem_sparse", .mode = 0600 },
+	.size = PCI_LEGACY_MEM_SIZE << 5,
+	.mmap = pci_mmap_legacy_mem,
+	.llseek = pci_llseek_resource_legacy,
+	.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