diff options
Diffstat (limited to 'Documentation/filesystems')
| -rw-r--r-- | Documentation/filesystems/index.rst | 1 | ||||
| -rw-r--r-- | Documentation/filesystems/sysfs-pci.rst (renamed from Documentation/filesystems/sysfs-pci.txt) | 23 |
2 files changed, 16 insertions, 8 deletions
diff --git a/Documentation/filesystems/index.rst b/Documentation/filesystems/index.rst index 5fb2b2166204..7afb58dff43b 100644 --- a/Documentation/filesystems/index.rst +++ b/Documentation/filesystems/index.rst @@ -34,6 +34,7 @@ algorithms work. quota seq_file sharedsubtree + sysfs-pci automount-support diff --git a/Documentation/filesystems/sysfs-pci.txt b/Documentation/filesystems/sysfs-pci.rst index 06f1d64c6f70..a265f3e2cc80 100644 --- a/Documentation/filesystems/sysfs-pci.txt +++ b/Documentation/filesystems/sysfs-pci.rst @@ -1,8 +1,11 @@ +.. SPDX-License-Identifier: GPL-2.0 + +============================================ 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: +that support it. For example, a given bus might look like this:: /sys/devices/pci0000:17 |-- 0000:17:00.0 @@ -30,8 +33,9 @@ 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) device PCI device (ascii, ro) @@ -40,13 +44,16 @@ files, each with their own function. local_cpus nearby CPU mask (cpumask, ro) remove remove device from kernel's list (ascii, wo) resource PCI resource host addresses (ascii, ro) - resource0..N PCI resource N, if present (binary, mmap, rw[1]) + resource0..N PCI resource N, if present (binary, mmap, rw\ [1]_) resource0_wc..N_wc PCI WC map resource N, if prefetchable (binary, mmap) revision PCI revision (ascii, ro) 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 @@ -56,7 +63,7 @@ files, each with their own function. binary - file contains binary data cpumask - file contains a cpumask type -[1] rw for RESOURCE_IO (I/O port) regions only +.. [1] rw for RESOURCE_IO (I/O port) regions only The read only files are informational, writes to them will be ignored, with the exception of the 'rom' file. Writable files can be used to perform @@ -67,11 +74,11 @@ don't support mmapping of certain resources, so be sure to check the return value from any attempted mmap. The most notable of these are I/O port resources, which also provide read/write access. -The 'enable' file provides a counter that indicates how many times the device +The 'enable' file provides a counter that indicates how many times the device has been enabled. If the 'enable' file currently returns '4', and a '1' is echoed into it, it will then return '5'. Echoing a '0' into it will decrease the count. Even when it returns to 0, though, some of the initialisation -may not be reversed. +may not be reversed. The 'rom' file is special in that it provides read-only access to the device's ROM file, if available. It's disabled by default, however, so applications @@ -93,7 +100,7 @@ Accessing legacy resources through sysfs Legacy I/O port and ISA memory resources are also provided in sysfs if the underlying platform supports them. They're located in the PCI class hierarchy, -e.g. +e.g.:: /sys/class/pci_bus/0000:17/ |-- bridge -> ../../../devices/pci0000:17 |