Re: [PATCH] USB and Driver Core patches for 2.6.10

Greg KH
2005-01-08T07:58:18Z

ChangeSet 1.1938.444.27, 2004/12/21 12:12:05-08:00, jbarnes@engr.sgi.com

[PATCH] PCI: export PCI resources in sysfs

This patch exports PCI resources to userspace in the corresponding sysfs
device directory. It depends on the platform HAVE_PCI_MMAP code, and is
#ifdef'd accordingly. I've also added documentation describing the sysfs PCI
device file layout.

Signed-off-by: Jesse Barnes <jbarnes@sgi.com>
Signed-off-by: Greg Kroah-Hartman <greg@kroah.com>

Documentation/filesystems/sysfs-pci.txt | 64 ++++++++++++++++++++++
drivers/pci/pci-sysfs.c | 92 ++++++++++++++++++++++++++++++++
include/linux/pci.h | 1
3 files changed, 157 insertions(+)

diff -Nru a/Documentation/filesystems/sysfs-pci.txt b/Documentation/filesystems/sysfs-pci.txt
--- /dev/null Wed Dec 31 16:00:00 196900
+++ b/Documentation/filesystems/sysfs-pci.txt 2005-01-07 15:40:39 -08:00
@@ -0,0 +1,64 @@
+Accessing PCI device resources through sysfs
+
+sysfs, usually mounted at /sys, provides access to PCI resources on platforms
+that support it. For example, a given bus might look like this:
+
+ pci0000:17
+ |-- 0000:17:00.0
+ | |-- class
+ | |-- config
+ | |-- detach_state
+ | |-- device
+ | |-- irq
+ | |-- local_cpus
+ | |-- resource
+ | |-- resource0
+ | |-- resource1
+ | |-- resource2
+ | |-- rom
+ | |-- subsystem_device
+ | |-- subsystem_vendor
+ | `-- vendor
+ `-- detach_state
+
+The topmost element describes the PCI domain and bus number. In this case,
+the domain number is 0000 and the bus number is 17 (both values are in hex).
+This bus contains a single function device in slot 0. The domain and bus
+numbers are reproduced for convenience. Under the device directory are several
+files, each with their own function.
+
+ file function
+ ---- --------
+ class PCI class (ascii, ro)
+ config PCI config space (binary, rw)
+ detach_state connection status (bool, rw)
+ device PCI device (ascii, ro)
+ irq IRQ number (ascii, ro)
+ local_cpus nearby CPU mask (cpumask, ro)
+ resource PCI resource host addresses (ascii, ro)
+ resource0..N PCI resource N, if present (binary, mmap)
+ rom PCI ROM resource, if present (binary, ro)
+ subsystem_device PCI subsystem device (ascii, ro)
+ subsystem_vendor PCI subsystem vendor (ascii, ro)
+ vendor PCI vendor (ascii, ro)
+
+ ro - read only file
+ rw - file is readable and writable
+ mmap - file is mmapable
+ ascii - file contains ascii text
+ binary - file contains binary data
+ cpumask - file contains a cpumask type
+
+The read only files are informational, writes to them will be ignored.
+Writable files can be used to perform actions on the device (e.g. changing
+config space, detaching a device). mmapable files are available via an
+mmap of the file at offset 0 and can be used to do actual device programming
+from userspace. Note that some platforms don't support mmapping of certain
+resources, so be sure to check the return value from any attempted mmap.
+
+Supporting PCI access on new platforms
+
+In order to support PCI resource mapping as described above, Linux platform
+code must define HAVE_PCI_MMAP and provide a pci_mmap_page_range function.
+Platforms are free to only support subsets of the mmap functionality, but
+useful return codes should be provided.
diff -Nru a/drivers/pci/pci-sysfs.c b/drivers/pci/pci-sysfs.c
--- a/drivers/pci/pci-sysfs.c 2005-01-07 15:40:39 -08:00
+++ b/drivers/pci/pci-sysfs.c 2005-01-07 15:40:39 -08:00
@@ -20,6 +20,7 @@
#include <linux/pci.h>
#include <linux/stat.h>
#include <linux/topology.h>
+#include <linux/mm.h>

#include "pci.h"

@@ -178,6 +179,93 @@
return count;
}

+#ifdef HAVE_PCI_MMAP
+/**
+ * pci_mmap_resource - map a PCI resource into user memory space
+ * @kobj: kobject for mapping
+ * @attr: struct bin_attribute for the file being mapped
+ * @vma: struct vm_area_struct passed into the mmap
+ *
+ * Use the regular PCI mapping routines to map a PCI resource into userspace.
+ * FIXME: write combining? maybe automatic for prefetchable regions?
+ */
+static int
+pci_mmap_resource(struct kobject *kobj, struct bin_attribute *attr,
+ struct vm_area_struct *vma)
+{
+ struct pci_dev *pdev = to_pci_dev(container_of(kobj,
+ struct device, kobj));
+ struct resource *res = (struct resource *)attr->private;
+ enum pci_mmap_state mmap_type;
+
+ vma->vm_pgoff += res->start >> PAGE_SHIFT;
+ mmap_type = res->flags & IORESOURCE_MEM ? pci_mmap_mem : pci_mmap_io;
+
+ return pci_mmap_page_range(pdev, vma, mmap_type, 0);
+}
+
+/**
+ * pci_create_resource_files - create resource files in sysfs for @dev
+ * @dev: dev in question
+ *
+ * Walk the resources in @dev creating files for each resource available.
+ */
+static void
+pci_create_resource_files(struct pci_dev *pdev)
+{
+ int i;
+
+ /* Expose the PCI resources from this device as files */
+ for (i = 0; i < PCI_ROM_RESOURCE; i++) {
+ struct bin_attribute *res_attr;
+
+ /* skip empty resources */
+ if (!pci_resource_len(pdev, i))
+ continue;
+
+ res_attr = kmalloc(sizeof(*res_attr) + 10, GFP_ATOMIC);
+ if (res_attr) {
+ pdev->res_attr[i] = res_attr;
+ /* Allocated above after the res_attr struct */
+ res_attr->attr.name = (char *)(res_attr + 1);
+ sprintf(res_attr->attr.name, "resource%d", i);
+ res_attr->size = pci_resource_len(pdev, i);
+ res_attr->attr.mode = S_IRUSR | S_IWUSR;
+ res_attr->attr.owner = THIS_MODULE;
+ res_attr->mmap = pci_mmap_resource;
+ res_attr->private = &pdev->resource[i];
+ sysfs_create_bin_file(&pdev->dev.kobj, res_attr);
+ }
+ }
+}
+
+/**
+ * pci_remove_resource_files - cleanup resource files
+ * @dev: dev to cleanup
+ *
+ * If we created resource files for @dev, remove them from sysfs and
+ * free their resources.
+ */
+static void
+pci_remove_resource_files(struct pci_dev *pdev)
+{
+ int i;
+
+ for (i = 0; i < PCI_ROM_RESOURCE; i++) {
+ struct bin_attribute *res_attr;
+
+ res_attr = pdev->res_attr[i];
+ if (res_attr) {
+ sysfs_remove_bin_file(&pdev->dev.kobj, res_attr);
+ kfree(res_attr);
+ }
+ }
+}
+#else /* !HAVE_PCI_MMAP */
+static inline void pci_create_resource_files(struct pci_dev *dev) { return; }
+static inline void pci_remove_resource_files(struct pci_dev *dev) { return; }
+#endif /* HAVE_PCI_MMAP */
+
/**
* pci_write_rom - used to enable access to the PCI ROM display
* @kobj: kernel object handle
@@ -269,6 +357,8 @@
else
sysfs_create_bin_file(&pdev->dev.kobj, &pcie_config_attr);

+ pci_create_resource_files(pdev);
+
/* If the device has a ROM, try to expose it in sysfs. */
if (pci_resource_len(pdev, PCI_ROM_RESOURCE)) {
struct bin_attribute *rom_attr;
@@ -303,6 +393,8 @@
sysfs_remove_bin_file(&pdev->dev.kobj, &pci_config_attr);
else
sysfs_remove_bin_file(&pdev->dev.kobj, &pcie_config_attr);
+
+ pci_remove_resource_files(pdev);

if (pci_resource_len(pdev, PCI_ROM_RESOURCE)) {
if (pdev->rom_attr) {
diff -Nru a/include/linux/pci.h b/include/linux/pci.h
--- a/include/linux/pci.h 2005-01-07 15:40:39 -08:00
+++ b/include/linux/pci.h 2005-01-07 15:40:39 -08:00
@@ -539,6 +539,7 @@
u32 saved_config_space[16]; /* config space saved at suspend time */
struct bin_attribute *rom_attr; /* attribute descriptor for sysfs ROM entry */
int rom_attr_enabled; /* has display of the rom attribute been enabled? */
+ struct bin_attribute *res_attr[DEVICE_COUNT_RESOURCE]; /* sysfs file for resources */
#ifdef CONFIG_PCI_NAMES
#define PCI_NAME_SIZE 96
#define PCI_NAME_HALF __stringify(43) /* less than half to handle slop */