From 73969ff0eda233f140bcbed1251431387b43f383 Mon Sep 17 00:00:00 2001 From: Daniel Mack Date: Wed, 4 Mar 2009 23:27:14 -0800 Subject: Input: generic driver for rotary encoders on GPIOs This patch adds a generic driver for rotary encoders connected to GPIO pins of a system. It relies on gpiolib and generic hardware irqs. The documentation that also comes with this patch explains the concept and how to use the driver. Signed-off-by: Daniel Mack Tested-by: H Hartley Sweeten Signed-off-by: Dmitry Torokhov --- Documentation/input/rotary-encoder.txt | 101 +++++++++++++++++++++++++++++++++ 1 file changed, 101 insertions(+) create mode 100644 Documentation/input/rotary-encoder.txt (limited to 'Documentation') diff --git a/Documentation/input/rotary-encoder.txt b/Documentation/input/rotary-encoder.txt new file mode 100644 index 0000000..435102a --- /dev/null +++ b/Documentation/input/rotary-encoder.txt @@ -0,0 +1,101 @@ +rotary-encoder - a generic driver for GPIO connected devices +Daniel Mack , Feb 2009 + +0. Function +----------- + +Rotary encoders are devices which are connected to the CPU or other +peripherals with two wires. The outputs are phase-shifted by 90 degrees +and by triggering on falling and rising edges, the turn direction can +be determined. + +The phase diagram of these two outputs look like this: + + _____ _____ _____ + | | | | | | + Channel A ____| |_____| |_____| |____ + + : : : : : : : : : : : : + __ _____ _____ _____ + | | | | | | | + Channel B |_____| |_____| |_____| |__ + + : : : : : : : : : : : : + Event a b c d a b c d a b c d + + |<-------->| + one step + + +For more information, please see + http://en.wikipedia.org/wiki/Rotary_encoder + + +1. Events / state machine +------------------------- + +a) Rising edge on channel A, channel B in low state + This state is used to recognize a clockwise turn + +b) Rising edge on channel B, channel A in high state + When entering this state, the encoder is put into 'armed' state, + meaning that there it has seen half the way of a one-step transition. + +c) Falling edge on channel A, channel B in high state + This state is used to recognize a counter-clockwise turn + +d) Falling edge on channel B, channel A in low state + Parking position. If the encoder enters this state, a full transition + should have happend, unless it flipped back on half the way. The + 'armed' state tells us about that. + +2. Platform requirements +------------------------ + +As there is no hardware dependent call in this driver, the platform it is +used with must support gpiolib. Another requirement is that IRQs must be +able to fire on both edges. + + +3. Board integration +-------------------- + +To use this driver in your system, register a platform_device with the +name 'rotary-encoder' and associate the IRQs and some specific platform +data with it. + +struct rotary_encoder_platform_data is declared in +include/linux/rotary-encoder.h and needs to be filled with the number of +steps the encoder has and can carry information about externally inverted +signals (because of used invertig buffer or other reasons). + +Because GPIO to IRQ mapping is platform specific, this information must +be given in seperately to the driver. See the example below. + +------------------ + +/* board support file example */ + +#include +#include + +#define GPIO_ROTARY_A 1 +#define GPIO_ROTARY_B 2 + +static struct rotary_encoder_platform_data my_rotary_encoder_info = { + .steps = 24, + .axis = ABS_X, + .gpio_a = GPIO_ROTARY_A, + .gpio_b = GPIO_ROTARY_B, + .inverted_a = 0, + .inverted_b = 0, +}; + +static struct platform_device rotary_encoder_device = { + .name = "rotary-encoder", + .id = 0, + .dev = { + .platform_data = &my_rotary_encoder_info, + } +}; + -- cgit v1.1 From 6a3335b43342b42dd6c69b4bbbde15d622cb49ca Mon Sep 17 00:00:00 2001 From: Or Gerlitz Date: Wed, 8 Apr 2009 13:52:01 -0700 Subject: IPoIB: Document newish features Update the documentation to include connected mode, stateless offloads and interrupt moderation, and add a reference to the connected mode RFC. Signed-off-by: Or Gerlitz Signed-off-by: Roland Dreier --- Documentation/infiniband/ipoib.txt | 45 ++++++++++++++++++++++++++++++++++++++ 1 file changed, 45 insertions(+) (limited to 'Documentation') diff --git a/Documentation/infiniband/ipoib.txt b/Documentation/infiniband/ipoib.txt index 864ff32..6d40f00 100644 --- a/Documentation/infiniband/ipoib.txt +++ b/Documentation/infiniband/ipoib.txt @@ -24,6 +24,49 @@ Partitions and P_Keys The P_Key for any interface is given by the "pkey" file, and the main interface for a subinterface is in "parent." +Datagram vs Connected modes + + The IPoIB driver supports two modes of operation: datagram and + connected. The mode is set and read through an interface's + /sys/class/net//mode file. + + In datagram mode, the IB UD (Unreliable Datagram) transport is used + and so the interface MTU has is equal to the IB L2 MTU minus the + IPoIB encapsulation header (4 bytes). For example, in a typical IB + fabric with a 2K MTU, the IPoIB MTU will be 2048 - 4 = 2044 bytes. + + In connected mode, the IB RC (Reliable Connected) transport is used. + Connected mode is to takes advantage of the connected nature of the + IB transport and allows an MTU up to the maximal IP packet size of + 64K, which reduces the number of IP packets needed for handling + large UDP datagrams, TCP segments, etc and increases the performance + for large messages. + + In connected mode, the interface's UD QP is still used for multicast + and communication with peers that don't support connected mode. In + this case, RX emulation of ICMP PMTU packets is used to cause the + networking stack to use the smaller UD MTU for these neighbours. + +Stateless offloads + + If the IB HW supports IPoIB stateless offloads, IPoIB advertises + TCP/IP checksum and/or Large Send (LSO) offloading capability to the + network stack. + + Large Receive (LRO) offloading is also implemented and may be turned + on/off using ethtool calls. Currently LRO is supported only for + checksum offload capable devices. + + Stateless offloads are supported only in datagram mode. + +Interrupt moderation + + If the underlying IB device supports CQ event moderation, one can + use ethtool to set interrupt mitigation parameters and thus reduce + the overhead incurred by handling interrupts. The main code path of + IPoIB doesn't use events for TX completion signaling so only RX + moderation is supported. + Debugging Information By compiling the IPoIB driver with CONFIG_INFINIBAND_IPOIB_DEBUG set @@ -55,3 +98,5 @@ References http://ietf.org/rfc/rfc4391.txt IP over InfiniBand (IPoIB) Architecture (RFC 4392) http://ietf.org/rfc/rfc4392.txt + IP over InfiniBand: Connected Mode (RFC 4755) + http://ietf.org/rfc/rfc4755.txt -- cgit v1.1 From c7bb349e7c25df1ae1bbb72675b9bb02e1d9c464 Mon Sep 17 00:00:00 2001 From: Sam Ravnborg Date: Fri, 10 Apr 2009 08:52:43 +0200 Subject: kbuild: introduce destination-y for exported headers xtensa and arm have asked for a possibility to export headers and locate them in a specific directory when exported. Introduce destiantion-y to support this. This patch in additiona adds some limited documentation for the variables used for exported headers. Signed-off-by: Sam Ravnborg Cc: Oskar Schirmer Cc: Mikael Starvik --- Documentation/kbuild/makefiles.txt | 83 ++++++++++++++++++++++++++++++++++---- 1 file changed, 75 insertions(+), 8 deletions(-) (limited to 'Documentation') diff --git a/Documentation/kbuild/makefiles.txt b/Documentation/kbuild/makefiles.txt index 51104f9..d4b0567 100644 --- a/Documentation/kbuild/makefiles.txt +++ b/Documentation/kbuild/makefiles.txt @@ -40,10 +40,16 @@ This document describes the Linux kernel Makefiles. --- 6.7 Custom kbuild commands --- 6.8 Preprocessing linker scripts - === 7 Kbuild Variables - === 8 Makefile language - === 9 Credits - === 10 TODO + === 7 Kbuild syntax for exported headers + --- 7.1 header-y + --- 7.2 objhdr-y + --- 7.3 destination-y + --- 7.4 unifdef-y (deprecated) + + === 8 Kbuild Variables + === 9 Makefile language + === 10 Credits + === 11 TODO === 1 Overview @@ -1143,8 +1149,69 @@ When kbuild executes, the following steps are followed (roughly): The kbuild infrastructure for *lds file are used in several architecture-specific files. +=== 7 Kbuild syntax for exported headers + +The kernel include a set of headers that is exported to userspace. +Many headers can be exported as-is but other headers requires a +minimal pre-processing before they are ready for user-space. +The pre-processing does: +- drop kernel specific annotations +- drop include of compiler.h +- drop all sections that is kernel internat (guarded by ifdef __KERNEL__) + +Each relevant directory contain a file name "Kbuild" which specify the +headers to be exported. +See subsequent chapter for the syntax of the Kbuild file. + + --- 7.1 header-y + + header-y specify header files to be exported. + + Example: + #include/linux/Kbuild + header-y += usb/ + header-y += aio_abi.h + + The convention is to list one file per line and + preferably in alphabetic order. + + header-y also specify which subdirectories to visit. + A subdirectory is identified by a trailing '/' which + can be seen in the example above for the usb subdirectory. + + Subdirectories are visited before their parent directories. + + --- 7.2 objhdr-y + + objhdr-y specifies generated files to be exported. + Generated files are special as they need to be looked + up in another directory when doing 'make O=...' builds. + + Example: + #include/linux/Kbuild + objhdr-y += version.h + + --- 7.3 destination-y + + When an architecture have a set of exported headers that needs to be + exported to a different directory destination-y is used. + destination-y specify the destination directory for all exported + headers in the file where it is present. + + Example: + #arch/xtensa/platforms/s6105/include/platform/Kbuild + destination-y := include/linux + + In the example above all exported headers in the Kbuild file + will be located in the directory "include/linux" when exported. + + + --- 7.4 unifdef-y (deprecated) + + unifdef-y is deprecated. A direct replacement is header-y. + -=== 7 Kbuild Variables +=== 8 Kbuild Variables The top Makefile exports the following variables: @@ -1206,7 +1273,7 @@ The top Makefile exports the following variables: INSTALL_MOD_STRIP will used as the option(s) to the strip command. -=== 8 Makefile language +=== 9 Makefile language The kernel Makefiles are designed to be run with GNU Make. The Makefiles use only the documented features of GNU Make, but they do use many @@ -1225,14 +1292,14 @@ time the left-hand side is used. There are some cases where "=" is appropriate. Usually, though, ":=" is the right choice. -=== 9 Credits +=== 10 Credits Original version made by Michael Elizabeth Chastain, Updates by Kai Germaschewski Updates by Sam Ravnborg Language QA by Jan Engelhardt -=== 10 TODO +=== 11 TODO - Describe how kbuild supports shipped files with _shipped. - Generating offset header files. -- cgit v1.1 From 20375bf82567b5fecd331048c6cc1fc292b67710 Mon Sep 17 00:00:00 2001 From: Sam Ravnborg Date: Fri, 10 Apr 2009 13:18:08 +0200 Subject: Documentation: explain the difference between __bitwise and __bitwise__ Simply added explanation from Al Viro in the following mail: http://lkml.indiana.edu/hypermail/linux/kernel/0802.2/3164.html Cc: Al Viro Cc: Randy Dunlap Signed-off-by: Sam Ravnborg --- Documentation/sparse.txt | 8 ++++++++ 1 file changed, 8 insertions(+) (limited to 'Documentation') diff --git a/Documentation/sparse.txt b/Documentation/sparse.txt index 42f43fa..34c76a5 100644 --- a/Documentation/sparse.txt +++ b/Documentation/sparse.txt @@ -42,6 +42,14 @@ sure that bitwise types don't get mixed up (little-endian vs big-endian vs cpu-endian vs whatever), and there the constant "0" really _is_ special. +__bitwise__ - to be used for relatively compact stuff (gfp_t, etc.) that +is mostly warning-free and is supposed to stay that way. Warnings will +be generated without __CHECK_ENDIAN__. + +__bitwise - noisy stuff; in particular, __le*/__be* are that. We really +don't want to drown in noise unless we'd explicitly asked for it. + + Getting sparse ~~~~~~~~~~~~~~ -- cgit v1.1 From 2810ae8c73cbfb37891aa99dfbca46ffd40dbc91 Mon Sep 17 00:00:00 2001 From: Randy Dunlap Date: Fri, 10 Apr 2009 14:20:54 -0700 Subject: docbook: make cleandocs Add a 'make cleandocs' target to clean up all generated DocBook files. Signed-off-by: Randy Dunlap Signed-off-by: Sam Ravnborg --- Documentation/DocBook/Makefile | 11 ++++++++--- 1 file changed, 8 insertions(+), 3 deletions(-) (limited to 'Documentation') diff --git a/Documentation/DocBook/Makefile b/Documentation/DocBook/Makefile index a3a83d3..8918a32 100644 --- a/Documentation/DocBook/Makefile +++ b/Documentation/DocBook/Makefile @@ -31,7 +31,7 @@ PS_METHOD = $(prefer-db2x) ### # The targets that may be used. -PHONY += xmldocs sgmldocs psdocs pdfdocs htmldocs mandocs installmandocs +PHONY += xmldocs sgmldocs psdocs pdfdocs htmldocs mandocs installmandocs cleandocs BOOKS := $(addprefix $(obj)/,$(DOCBOOKS)) xmldocs: $(BOOKS) @@ -213,11 +213,12 @@ silent_gen_xml = : dochelp: @echo ' Linux kernel internal documentation in different formats:' @echo ' htmldocs - HTML' - @echo ' installmandocs - install man pages generated by mandocs' - @echo ' mandocs - man pages' @echo ' pdfdocs - PDF' @echo ' psdocs - Postscript' @echo ' xmldocs - XML DocBook' + @echo ' mandocs - man pages' + @echo ' installmandocs - install man pages generated by mandocs' + @echo ' cleandocs - clean all generated DocBook files' ### # Temporary files left by various tools @@ -235,6 +236,10 @@ clean-files := $(DOCBOOKS) \ clean-dirs := $(patsubst %.xml,%,$(DOCBOOKS)) man +cleandocs: + $(Q)rm -f $(call objectify, $(clean-files)) + $(Q)rm -rf $(call objectify, $(clean-dirs)) + # Declare the contents of the .PHONY variable as phony. We keep that # information in a variable se we can use it in if_changed and friends. -- cgit v1.1 From 3f307fb37a6dd65b7eabda9c6208a9bd161dc16e Mon Sep 17 00:00:00 2001 From: Jean Delvare Date: Mon, 13 Apr 2009 17:02:13 +0200 Subject: i2c-voodoo3: Deprecate in favor of tdfxfb Support for I2C/DDC was recently added to the tdfxfb driver, which means that the i2c-voodoo3 driver can be deprecated. Signed-off-by: Jean Delvare Cc: Krzysztof Helt --- Documentation/feature-removal-schedule.txt | 9 +++++++++ 1 file changed, 9 insertions(+) (limited to 'Documentation') diff --git a/Documentation/feature-removal-schedule.txt b/Documentation/feature-removal-schedule.txt index 7e2af10..de491a3 100644 --- a/Documentation/feature-removal-schedule.txt +++ b/Documentation/feature-removal-schedule.txt @@ -428,3 +428,12 @@ Why: In 2.6.27, the semantics of /sys/bus/pci/slots was redefined to After a reasonable transition period, we will remove the legacy fakephp interface. Who: Alex Chiang + +--------------------------- + +What: i2c-voodoo3 driver +When: October 2009 +Why: Superseded by tdfxfb. I2C/DDC support used to live in a separate + driver but this caused driver conflicts. +Who: Jean Delvare + Krzysztof Helt -- cgit v1.1