ext4: Use tracepoints for mb_history trace file

[safe/jmp/linux-2.6] / Documentation / filesystems / sysfs-pci.txt

diff --git a/Documentation/filesystems/sysfs-pci.txt b/Documentation/filesystems/sysfs-pci.txt
index 68ef488..85354b3 100644 (file)
--- a/Documentation/filesystems/sysfs-pci.txt
+++ b/Documentation/filesystems/sysfs-pci.txt
@@ -9,8 +9,10 @@ that support it.  For example, a given bus might look like this:
      |   |-- class
      |   |-- config
      |   |-- device
+     |   |-- enable
      |   |-- irq
      |   |-- local_cpus
+     |   |-- remove
      |   |-- resource
      |   |-- resource0
      |   |-- resource1
@@ -32,8 +34,10 @@ 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)
+       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)
        resource0_wc..N_wc  PCI WC map resource N, if prefetchable (binary, mmap)
@@ -44,6 +48,7 @@ files, each with their own function.
 
   ro - read only file
   rw - file is readable and writable
+  wo - write only file
   mmap - file is mmapable
   ascii - file contains ascii text
   binary - file contains binary data
@@ -57,10 +62,26 @@ 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 successfully.
+In the event a driver is not bound to the device, it can be enabled using the
+'enable' file, documented above.
+
+The 'remove' file is used to remove the PCI device, by writing a non-zero
+integer to the file.  This does not involve any kind of hot-plug functionality,
+e.g. powering off the device.  The device is removed from the kernel's list of
+PCI devices, the sysfs directory for it is removed, and the device will be
+removed from any drivers attached to it. Removal of PCI root buses is
+disallowed.
 
 Accessing legacy resources through sysfs
 ----------------------------------------