diff options
Diffstat (limited to 'Documentation')
| -rw-r--r-- | Documentation/ABI/testing/sysfs-dev | 20 | ||||
| -rw-r--r-- | Documentation/DocBook/uio-howto.tmpl | 63 | ||||
| -rw-r--r-- | Documentation/HOWTO | 2 | ||||
| -rw-r--r-- | Documentation/filesystems/sysfs.txt | 6 | ||||
| -rw-r--r-- | Documentation/sysfs-rules.txt | 5 |
5 files changed, 80 insertions, 16 deletions
diff --git a/Documentation/ABI/testing/sysfs-dev b/Documentation/ABI/testing/sysfs-dev new file mode 100644 index 000000000000..a9f2b8b0530f --- /dev/null +++ b/Documentation/ABI/testing/sysfs-dev @@ -0,0 +1,20 @@ +What: /sys/dev +Date: April 2008 +KernelVersion: 2.6.26 +Contact: Dan Williams <dan.j.williams@intel.com> +Description: The /sys/dev tree provides a method to look up the sysfs + path for a device using the information returned from + stat(2). There are two directories, 'block' and 'char', + beneath /sys/dev containing symbolic links with names of + the form "<major>:<minor>". These links point to the + corresponding sysfs path for the given device. + + Example: + $ readlink /sys/dev/block/8:32 + ../../block/sdc + + Entries in /sys/dev/char and /sys/dev/block will be + dynamically created and destroyed as devices enter and + leave the system. + +Users: mdadm <linux-raid@vger.kernel.org> diff --git a/Documentation/DocBook/uio-howto.tmpl b/Documentation/DocBook/uio-howto.tmpl index fdd7f4f887b7..df87d1b93605 100644 --- a/Documentation/DocBook/uio-howto.tmpl +++ b/Documentation/DocBook/uio-howto.tmpl @@ -21,6 +21,18 @@ </affiliation> </author> +<copyright> + <year>2006-2008</year> + <holder>Hans-Jürgen Koch.</holder> +</copyright> + +<legalnotice> +<para> +This documentation is Free Software licensed under the terms of the +GPL version 2. +</para> +</legalnotice> + <pubdate>2006-12-11</pubdate> <abstract> @@ -30,6 +42,12 @@ <revhistory> <revision> + <revnumber>0.5</revnumber> + <date>2008-05-22</date> + <authorinitials>hjk</authorinitials> + <revremark>Added description of write() function.</revremark> + </revision> + <revision> <revnumber>0.4</revnumber> <date>2007-11-26</date> <authorinitials>hjk</authorinitials> @@ -57,20 +75,9 @@ </bookinfo> <chapter id="aboutthisdoc"> -<?dbhtml filename="about.html"?> +<?dbhtml filename="aboutthis.html"?> <title>About this document</title> -<sect1 id="copyright"> -<?dbhtml filename="copyright.html"?> -<title>Copyright and License</title> -<para> - Copyright (c) 2006 by Hans-Jürgen Koch.</para> -<para> -This documentation is Free Software licensed under the terms of the -GPL version 2. -</para> -</sect1> - <sect1 id="translations"> <?dbhtml filename="translations.html"?> <title>Translations</title> @@ -189,6 +196,30 @@ interested in translating it, please email me represents the total interrupt count. You can use this number to figure out if you missed some interrupts. </para> + <para> + For some hardware that has more than one interrupt source internally, + but not separate IRQ mask and status registers, there might be + situations where userspace cannot determine what the interrupt source + was if the kernel handler disables them by writing to the chip's IRQ + register. In such a case, the kernel has to disable the IRQ completely + to leave the chip's register untouched. Now the userspace part can + determine the cause of the interrupt, but it cannot re-enable + interrupts. Another cornercase is chips where re-enabling interrupts + is a read-modify-write operation to a combined IRQ status/acknowledge + register. This would be racy if a new interrupt occurred + simultaneously. + </para> + <para> + To address these problems, UIO also implements a write() function. It + is normally not used and can be ignored for hardware that has only a + single interrupt source or has separate IRQ mask and status registers. + If you need it, however, a write to <filename>/dev/uioX</filename> + will call the <function>irqcontrol()</function> function implemented + by the driver. You have to write a 32-bit value that is usually either + 0 or 1 to disable or enable interrupts. If a driver does not implement + <function>irqcontrol()</function>, <function>write()</function> will + return with <varname>-ENOSYS</varname>. + </para> <para> To handle interrupts properly, your custom kernel module can @@ -362,6 +393,14 @@ device is actually used. <function>open()</function>, you will probably also want a custom <function>release()</function> function. </para></listitem> + +<listitem><para> +<varname>int (*irqcontrol)(struct uio_info *info, s32 irq_on) +</varname>: Optional. If you need to be able to enable or disable +interrupts from userspace by writing to <filename>/dev/uioX</filename>, +you can implement this function. The parameter <varname>irq_on</varname> +will be 0 to disable interrupts and 1 to enable them. +</para></listitem> </itemizedlist> <para> diff --git a/Documentation/HOWTO b/Documentation/HOWTO index 619e8caf30db..c2371c5a98f9 100644 --- a/Documentation/HOWTO +++ b/Documentation/HOWTO @@ -358,7 +358,7 @@ Here is a list of some of the different kernel trees available: - pcmcia, Dominik Brodowski <linux@dominikbrodowski.net> git.kernel.org:/pub/scm/linux/kernel/git/brodo/pcmcia-2.6.git - - SCSI, James Bottomley <James.Bottomley@SteelEye.com> + - SCSI, James Bottomley <James.Bottomley@hansenpartnership.com> git.kernel.org:/pub/scm/linux/kernel/git/jejb/scsi-misc-2.6.git - x86, Ingo Molnar <mingo@elte.hu> diff --git a/Documentation/filesystems/sysfs.txt b/Documentation/filesystems/sysfs.txt index 7f27b8f840d0..9e9c348275a9 100644 --- a/Documentation/filesystems/sysfs.txt +++ b/Documentation/filesystems/sysfs.txt @@ -248,6 +248,7 @@ The top level sysfs directory looks like: block/ bus/ class/ +dev/ devices/ firmware/ net/ @@ -274,6 +275,11 @@ fs/ contains a directory for some filesystems. Currently each filesystem wanting to export attributes must create its own hierarchy below fs/ (see ./fuse.txt for an example). +dev/ contains two directories char/ and block/. Inside these two +directories there are symlinks named <major>:<minor>. These symlinks +point to the sysfs directory for the given device. /sys/dev provides a +quick way to lookup the sysfs interface for a device from the result of +a stat(2) operation. More information can driver-model specific features can be found in Documentation/driver-model/. diff --git a/Documentation/sysfs-rules.txt b/Documentation/sysfs-rules.txt index 80ef562160bb..6049a2a84dda 100644 --- a/Documentation/sysfs-rules.txt +++ b/Documentation/sysfs-rules.txt @@ -3,9 +3,8 @@ Rules on how to access information in the Linux kernel sysfs The kernel-exported sysfs exports internal kernel implementation details and depends on internal kernel structures and layout. It is agreed upon by the kernel developers that the Linux kernel does not provide a stable -internal API. As sysfs is a direct export of kernel internal -structures, the sysfs interface cannot provide a stable interface either; -it may always change along with internal kernel changes. +internal API. Therefore, there are aspects of the sysfs interface that +may not be stable across kernel releases. To minimize the risk of breaking users of sysfs, which are in most cases low-level userspace applications, with a new kernel release, the users |