path: root/Documentation
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authorLinus Torvalds <torvalds@linux-foundation.org>2009-02-07 10:46:30 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2009-02-07 10:46:30 -0800
commite83102cab0fd95d4508361b061146c978b3abd60 (patch)
treed1452292bf5d55da6a072d36d507d2e918ee2180 /Documentation
parent7f9a50a5b89b87f8e754f59ae9968da28be618a5 (diff)
parent5294e256717923f4a3297bb8b802f5e0625763f3 (diff)
Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jbarnes/pci-2.6
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jbarnes/pci-2.6: PCI PM: make the PM core more careful with drivers using the new PM framework PCI PM: Read power state from device after trying to change it on resume PCI PM: Do not disable and enable bridges during suspend-resume PCI: PCIe portdrv: Simplify suspend and resume PCI PM: Fix saving of device state in pci_legacy_suspend PCI PM: Check if the state has been saved before trying to restore it PCI PM: Fix handling of devices without drivers PCI: return error on failure to read PCI ROMs PCI: properly clean up ASPM link state on device remove
Diffstat (limited to 'Documentation')
1 files changed, 12 insertions, 1 deletions
diff --git a/Documentation/filesystems/sysfs-pci.txt b/Documentation/filesystems/sysfs-pci.txt
index 68ef48839c0..9f8740ca3f3 100644
--- a/Documentation/filesystems/sysfs-pci.txt
+++ b/Documentation/filesystems/sysfs-pci.txt
@@ -9,6 +9,7 @@ that support it. For example, a given bus might look like this:
| |-- class
| |-- config
| |-- device
+ | |-- enable
| |-- irq
| |-- local_cpus
| |-- resource
@@ -32,6 +33,7 @@ files, each with their own function.
class PCI class (ascii, ro)
config PCI config space (binary, rw)
device PCI device (ascii, ro)
+ enable Whether the device is enabled (ascii, rw)
irq IRQ number (ascii, ro)
local_cpus nearby CPU mask (cpumask, ro)
resource PCI resource host addresses (ascii, ro)
@@ -57,10 +59,19 @@ 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.
+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.
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
should write the string "1" to the file to enable it before attempting a read
-call, and disable it following the access by writing "0" to the file.
+call, and disable it following the access by writing "0" to the file. Note
+that the device must be enabled for a rom read to return data succesfully.
+In the event a driver is not bound to the device, it can be enabled using the
+'enable' file, documented above.
Accessing legacy resources through sysfs