€•z‡      Œsphinx.addnodes”Œdocument”“”)”}”(Œ	rawsource”Œ ”Œchildren”]”(Œtranslations”ŒLanguagesNode”“”)”}”(hhh]”(h Œpending_xref”“”)”}”(hhh]”Œdocutils.nodes”ŒText”“”ŒChinese (Simplified)”…””}”Œparent”hsbaŒ
attributes”}”(Œids”]”Œclasses”]”Œnames”]”Œdupnames”]”Œbackrefs”]”Œ	refdomain”Œstd”Œreftype”Œdoc”Œ	reftarget”Œ/translations/zh_CN/spi/spidev”Œmodname”NŒ	classname”NŒrefexplicit”ˆuŒtagname”hhhubh)”}”(hhh]”hŒChinese (Traditional)”…””}”hh2sbah}”(h]”h ]”h"]”h$]”h&]”Œ	refdomain”h)Œreftype”h+Œ	reftarget”Œ/translations/zh_TW/spi/spidev”Œmodname”NŒ	classname”NŒrefexplicit”ˆuh1hhhubh)”}”(hhh]”hŒItalian”…””}”hhFsbah}”(h]”h ]”h"]”h$]”h&]”Œ	refdomain”h)Œreftype”h+Œ	reftarget”Œ/translations/it_IT/spi/spidev”Œmodname”NŒ	classname”NŒrefexplicit”ˆuh1hhhubh)”}”(hhh]”hŒJapanese”…””}”hhZsbah}”(h]”h ]”h"]”h$]”h&]”Œ	refdomain”h)Œreftype”h+Œ	reftarget”Œ/translations/ja_JP/spi/spidev”Œmodname”NŒ	classname”NŒrefexplicit”ˆuh1hhhubh)”}”(hhh]”hŒKorean”…””}”hhnsbah}”(h]”h ]”h"]”h$]”h&]”Œ	refdomain”h)Œreftype”h+Œ	reftarget”Œ/translations/ko_KR/spi/spidev”Œmodname”NŒ	classname”NŒrefexplicit”ˆuh1hhhubh)”}”(hhh]”hŒSpanish”…””}”hh‚sbah}”(h]”h ]”h"]”h$]”h&]”Œ	refdomain”h)Œreftype”h+Œ	reftarget”Œ/translations/sp_SP/spi/spidev”Œmodname”NŒ	classname”NŒrefexplicit”ˆuh1hhhubeh}”(h]”h ]”h"]”h$]”h&]”Œcurrent_language”ŒEnglish”uh1h
hhŒ	_document”hŒsource”NŒline”NubhŒsection”“”)”}”(hhh]”(hŒtitle”“”)”}”(hŒSPI userspace API”h]”hŒSPI userspace API”…””}”(hh¨hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h¦hh£hžhhŸŒ8/var/lib/git/docbuild/linux/Documentation/spi/spidev.rst”h KubhŒ	paragraph”“”)”}”(hŒÖSPI devices have a limited userspace API, supporting basic half-duplex
read() and write() access to SPI slave devices.  Using ioctl() requests,
full duplex transfers and device I/O configuration are also available.”h]”hŒÖSPI devices have a limited userspace API, supporting basic half-duplex
read() and write() access to SPI slave devices.  Using ioctl() requests,
full duplex transfers and device I/O configuration are also available.”…””}”(hh¹hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h Khh£hžhubhŒliteral_block”“”)”}”(hŒt#include <fcntl.h>
#include <unistd.h>
#include <sys/ioctl.h>
#include <linux/types.h>
#include <linux/spi/spidev.h>”h]”hŒt#include <fcntl.h>
#include <unistd.h>
#include <sys/ioctl.h>
#include <linux/types.h>
#include <linux/spi/spidev.h>”…””}”hhÉsbah}”(h]”h ]”h"]”h$]”h&]”Œ	xml:space”Œpreserve”uh1hÇhŸh¶h Khh£hžhubh¸)”}”(hŒFSome reasons you might want to use this programming interface include:”h]”hŒFSome reasons you might want to use this programming interface include:”…””}”(hhÙhžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h Khh£hžhubhŒblock_quote”“”)”}”(hX  * Prototyping in an environment that's not crash-prone; stray pointers
  in userspace won't normally bring down any Linux system.

* Developing simple protocols used to talk to microcontrollers acting
  as SPI slaves, which you may need to change quite often.
”h]”hŒbullet_list”“”)”}”(hhh]”(hŒ	list_item”“”)”}”(hŒ~Prototyping in an environment that's not crash-prone; stray pointers
in userspace won't normally bring down any Linux system.
”h]”h¸)”}”(hŒ}Prototyping in an environment that's not crash-prone; stray pointers
in userspace won't normally bring down any Linux system.”h]”hŒPrototyping in an environment thatâ€™s not crash-prone; stray pointers
in userspace wonâ€™t normally bring down any Linux system.”…””}”(hhøhžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h Khhôubah}”(h]”h ]”h"]”h$]”h&]”uh1hòhhïubhó)”}”(hŒ}Developing simple protocols used to talk to microcontrollers acting
as SPI slaves, which you may need to change quite often.
”h]”h¸)”}”(hŒ|Developing simple protocols used to talk to microcontrollers acting
as SPI slaves, which you may need to change quite often.”h]”hŒ|Developing simple protocols used to talk to microcontrollers acting
as SPI slaves, which you may need to change quite often.”…””}”(hj  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h Khj  ubah}”(h]”h ]”h"]”h$]”h&]”uh1hòhhïubeh}”(h]”h ]”h"]”h$]”h&]”Œbullet”Œ*”uh1híhŸh¶h Khhéubah}”(h]”h ]”h"]”h$]”h&]”uh1hçhŸh¶h Khh£hžhubh¸)”}”(hŒÒOf course there are drivers that can never be written in userspace, because
they need to access kernel interfaces (such as IRQ handlers or other layers
of the driver stack) that are not accessible to userspace.”h]”hŒÒOf course there are drivers that can never be written in userspace, because
they need to access kernel interfaces (such as IRQ handlers or other layers
of the driver stack) that are not accessible to userspace.”…””}”(hj2  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h Khh£hžhubh¢)”}”(hhh]”(h§)”}”(hŒDEVICE CREATION, DRIVER BINDING”h]”hŒDEVICE CREATION, DRIVER BINDING”…””}”(hjC  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h¦hj@  hžhhŸh¶h Kubh¸)”}”(hŒwThe spidev driver contains lists of SPI devices that are supported for
the different hardware topology representations.”h]”hŒwThe spidev driver contains lists of SPI devices that are supported for
the different hardware topology representations.”…””}”(hjQ  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h K!hj@  hžhubh¸)”}”(hŒGThe following are the SPI device tables supported by the spidev driver:”h]”hŒGThe following are the SPI device tables supported by the spidev driver:”…””}”(hj_  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h K$hj@  hžhubhè)”}”(hXD  - struct spi_device_id spidev_spi_ids[]: list of devices that can be
  bound when these are defined using a struct spi_board_info with a
  .modalias field matching one of the entries in the table.

- struct of_device_id spidev_dt_ids[]: list of devices that can be
  bound when these are defined using a Device Tree node that has a
  compatible string matching one of the entries in the table.

- struct acpi_device_id spidev_acpi_ids[]: list of devices that can
  be bound when these are defined using a ACPI device object with a
  _HID matching one of the entries in the table.
”h]”hî)”}”(hhh]”(hó)”}”(hŒ¿struct spi_device_id spidev_spi_ids[]: list of devices that can be
bound when these are defined using a struct spi_board_info with a
.modalias field matching one of the entries in the table.
”h]”h¸)”}”(hŒ¾struct spi_device_id spidev_spi_ids[]: list of devices that can be
bound when these are defined using a struct spi_board_info with a
.modalias field matching one of the entries in the table.”h]”hŒ¾struct spi_device_id spidev_spi_ids[]: list of devices that can be
bound when these are defined using a struct spi_board_info with a
.modalias field matching one of the entries in the table.”…””}”(hjx  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h K&hjt  ubah}”(h]”h ]”h"]”h$]”h&]”uh1hòhjq  ubhó)”}”(hŒ¾struct of_device_id spidev_dt_ids[]: list of devices that can be
bound when these are defined using a Device Tree node that has a
compatible string matching one of the entries in the table.
”h]”h¸)”}”(hŒ½struct of_device_id spidev_dt_ids[]: list of devices that can be
bound when these are defined using a Device Tree node that has a
compatible string matching one of the entries in the table.”h]”hŒ½struct of_device_id spidev_dt_ids[]: list of devices that can be
bound when these are defined using a Device Tree node that has a
compatible string matching one of the entries in the table.”…””}”(hj  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h K*hjŒ  ubah}”(h]”h ]”h"]”h$]”h&]”uh1hòhjq  ubhó)”}”(hŒ³struct acpi_device_id spidev_acpi_ids[]: list of devices that can
be bound when these are defined using a ACPI device object with a
_HID matching one of the entries in the table.
”h]”h¸)”}”(hŒ²struct acpi_device_id spidev_acpi_ids[]: list of devices that can
be bound when these are defined using a ACPI device object with a
_HID matching one of the entries in the table.”h]”hŒ²struct acpi_device_id spidev_acpi_ids[]: list of devices that can
be bound when these are defined using a ACPI device object with a
_HID matching one of the entries in the table.”…””}”(hj¨  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h K.hj¤  ubah}”(h]”h ]”h"]”h$]”h&]”uh1hòhjq  ubeh}”(h]”h ]”h"]”h$]”h&]”j*  Œ-”uh1híhŸh¶h K&hjm  ubah}”(h]”h ]”h"]”h$]”h&]”uh1hçhŸh¶h K&hj@  hžhubh¸)”}”(hŒ×You are encouraged to add an entry for your SPI device name to relevant
tables, if these don't already have an entry for the device. To do that,
post a patch for spidev to the linux-spi@vger.kernel.org mailing list.”h]”(hŒ²You are encouraged to add an entry for your SPI device name to relevant
tables, if these donâ€™t already have an entry for the device. To do that,
post a patch for spidev to the ”…””}”(hjÉ  hžhhŸNh NubhŒ	reference”“”)”}”(hŒlinux-spi@vger.kernel.org”h]”hŒlinux-spi@vger.kernel.org”…””}”(hjÓ  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”Œrefuri”Œ mailto:linux-spi@vger.kernel.org”uh1jÑ  hjÉ  ubhŒ mailing list.”…””}”(hjÉ  hžhhŸNh Nubeh}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h K2hj@  hžhubh¸)”}”(hX  It used to be supported to define an SPI device using the "spidev" name.
For example, as .modalias = "spidev" or compatible = "spidev".  But this
is no longer supported by the Linux kernel and instead a real SPI device
name as listed in one of the tables must be used.”h]”hX  It used to be supported to define an SPI device using the â€œspidevâ€ name.
For example, as .modalias = â€œspidevâ€ or compatible = â€œspidevâ€.  But this
is no longer supported by the Linux kernel and instead a real SPI device
name as listed in one of the tables must be used.”…””}”(hjí  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h K6hj@  hžhubh¸)”}”(hŒmNot having a real SPI device name will lead to an error being printed and
the spidev driver failing to probe.”h]”hŒmNot having a real SPI device name will lead to an error being printed and
the spidev driver failing to probe.”…””}”(hjû  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h K;hj@  hžhubh¸)”}”(hŒÏSysfs also supports userspace driven binding/unbinding of drivers to
devices that do not bind automatically using one of the tables above.
To make the spidev driver bind to such a device, use the following::”h]”hŒÎSysfs also supports userspace driven binding/unbinding of drivers to
devices that do not bind automatically using one of the tables above.
To make the spidev driver bind to such a device, use the following:”…””}”(hj	  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h K>hj@  hžhubhÈ)”}”(hŒhecho spidev > /sys/bus/spi/devices/spiB.C/driver_override
echo spiB.C > /sys/bus/spi/drivers/spidev/bind”h]”hŒhecho spidev > /sys/bus/spi/devices/spiB.C/driver_override
echo spiB.C > /sys/bus/spi/drivers/spidev/bind”…””}”hj  sbah}”(h]”h ]”h"]”h$]”h&]”h×hØuh1hÇhŸh¶h KBhj@  hžhubh¸)”}”(hŒ÷When the spidev driver is bound to a SPI device, the sysfs node for the
device will include a child device node with a "dev" attribute that will
be understood by udev or mdev (udev replacement from BusyBox; it's less
featureful, but often enough).”h]”hŒýWhen the spidev driver is bound to a SPI device, the sysfs node for the
device will include a child device node with a â€œdevâ€ attribute that will
be understood by udev or mdev (udev replacement from BusyBox; itâ€™s less
featureful, but often enough).”…””}”(hj%  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h KEhj@  hžhubh¸)”}”(hŒ<For a SPI device with chipselect C on bus B, you should see:”h]”hŒ<For a SPI device with chipselect C on bus B, you should see:”…””}”(hj3  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h KJhj@  hžhubhè)”}”(hX
  /dev/spidevB.C ...
    character special device, major number 153 with
    a dynamically chosen minor device number.  This is the node
    that userspace programs will open, created by "udev" or "mdev".

/sys/devices/.../spiB.C ...
    as usual, the SPI device node will
    be a child of its SPI master controller.

/sys/class/spidev/spidevB.C ...
    created when the "spidev" driver
    binds to that device.  (Directory or symlink, based on whether
    or not you enabled the "deprecated sysfs files" Kconfig option.)
”h]”hŒdefinition_list”“”)”}”(hhh]”(hŒdefinition_list_item”“”)”}”(hŒ¿/dev/spidevB.C ...
character special device, major number 153 with
a dynamically chosen minor device number.  This is the node
that userspace programs will open, created by "udev" or "mdev".
”h]”(hŒterm”“”)”}”(hŒ/dev/spidevB.C ...”h]”hŒ/dev/spidevB.C ...”…””}”(hjR  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1jP  hŸh¶h KOhjL  ubhŒ
definition”“”)”}”(hhh]”h¸)”}”(hŒ«character special device, major number 153 with
a dynamically chosen minor device number.  This is the node
that userspace programs will open, created by "udev" or "mdev".”h]”hŒ³character special device, major number 153 with
a dynamically chosen minor device number.  This is the node
that userspace programs will open, created by â€œudevâ€ or â€œmdevâ€.”…””}”(hje  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h KMhjb  ubah}”(h]”h ]”h"]”h$]”h&]”uh1j`  hjL  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1jJ  hŸh¶h KOhjG  ubjK  )”}”(hŒh/sys/devices/.../spiB.C ...
as usual, the SPI device node will
be a child of its SPI master controller.
”h]”(jQ  )”}”(hŒ/sys/devices/.../spiB.C ...”h]”hŒ/sys/devices/.../spiB.C ...”…””}”(hjƒ  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1jP  hŸh¶h KShj  ubja  )”}”(hhh]”h¸)”}”(hŒKas usual, the SPI device node will
be a child of its SPI master controller.”h]”hŒKas usual, the SPI device node will
be a child of its SPI master controller.”…””}”(hj”  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h KRhj‘  ubah}”(h]”h ]”h"]”h$]”h&]”uh1j`  hj  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1jJ  hŸh¶h KShjG  ubjK  )”}”(hŒÁ/sys/class/spidev/spidevB.C ...
created when the "spidev" driver
binds to that device.  (Directory or symlink, based on whether
or not you enabled the "deprecated sysfs files" Kconfig option.)
”h]”(jQ  )”}”(hŒ/sys/class/spidev/spidevB.C ...”h]”hŒ/sys/class/spidev/spidevB.C ...”…””}”(hj²  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1jP  hŸh¶h KXhj®  ubja  )”}”(hhh]”h¸)”}”(hŒ created when the "spidev" driver
binds to that device.  (Directory or symlink, based on whether
or not you enabled the "deprecated sysfs files" Kconfig option.)”h]”hŒ¨created when the â€œspidevâ€ driver
binds to that device.  (Directory or symlink, based on whether
or not you enabled the â€œdeprecated sysfs filesâ€ Kconfig option.)”…””}”(hjÃ  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h KVhjÀ  ubah}”(h]”h ]”h"]”h$]”h&]”uh1j`  hj®  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1jJ  hŸh¶h KXhjG  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1jE  hjA  ubah}”(h]”h ]”h"]”h$]”h&]”uh1hçhŸh¶h KLhj@  hžhubh¸)”}”(hŒÒDo not try to manage the /dev character device special file nodes by hand.
That's error prone, and you'd need to pay careful attention to system
security issues; udev/mdev should already be configured securely.”h]”hŒÖDo not try to manage the /dev character device special file nodes by hand.
Thatâ€™s error prone, and youâ€™d need to pay careful attention to system
security issues; udev/mdev should already be configured securely.”…””}”(hjé  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h KZhj@  hžhubh¸)”}”(hX²  If you unbind the "spidev" driver from that device, those two "spidev" nodes
(in sysfs and in /dev) should automatically be removed (respectively by the
kernel and by udev/mdev).  You can unbind by removing the "spidev" driver
module, which will affect all devices using this driver.  You can also unbind
by having kernel code remove the SPI device, probably by removing the driver
for its SPI controller (so its spi_master vanishes).”h]”hX¾  If you unbind the â€œspidevâ€ driver from that device, those two â€œspidevâ€ nodes
(in sysfs and in /dev) should automatically be removed (respectively by the
kernel and by udev/mdev).  You can unbind by removing the â€œspidevâ€ driver
module, which will affect all devices using this driver.  You can also unbind
by having kernel code remove the SPI device, probably by removing the driver
for its SPI controller (so its spi_master vanishes).”…””}”(hj÷  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h K^hj@  hžhubh¸)”}”(hX%  Since this is a standard Linux device driver -- even though it just happens
to expose a low level API to userspace -- it can be associated with any number
of devices at a time.  Just provide one spi_board_info record for each such
SPI device, and you'll get a /dev device node for each device.”h]”hX'  Since this is a standard Linux device driver -- even though it just happens
to expose a low level API to userspace -- it can be associated with any number
of devices at a time.  Just provide one spi_board_info record for each such
SPI device, and youâ€™ll get a /dev device node for each device.”…””}”(hj  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h Kehj@  hžhubeh}”(h]”Œdevice-creation-driver-binding”ah ]”h"]”Œdevice creation, driver binding”ah$]”h&]”uh1h¡hh£hžhhŸh¶h Kubh¢)”}”(hhh]”(h§)”}”(hŒBASIC CHARACTER DEVICE API”h]”hŒBASIC CHARACTER DEVICE API”…””}”(hj  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h¦hj  hžhhŸh¶h Klubh¸)”}”(hŒVNormal open() and close() operations on /dev/spidevB.D files work as you
would expect.”h]”hŒVNormal open() and close() operations on /dev/spidevB.D files work as you
would expect.”…””}”(hj,  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h Kmhj  hžhubh¸)”}”(hX  Standard read() and write() operations are obviously only half-duplex, and
the chipselect is deactivated between those operations.  Full-duplex access,
and composite operation without chipselect de-activation, is available using
the SPI_IOC_MESSAGE(N) request.”h]”hX  Standard read() and write() operations are obviously only half-duplex, and
the chipselect is deactivated between those operations.  Full-duplex access,
and composite operation without chipselect de-activation, is available using
the SPI_IOC_MESSAGE(N) request.”…””}”(hj:  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h Kphj  hžhubh¸)”}”(hŒuSeveral ioctl() requests let your driver read or override the device's current
settings for data transfer parameters:”h]”hŒwSeveral ioctl() requests let your driver read or override the deviceâ€™s current
settings for data transfer parameters:”…””}”(hjH  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h Kuhj  hžhubhè)”}”(hXÇ  SPI_IOC_RD_MODE, SPI_IOC_WR_MODE ...
    pass a pointer to a byte which will
    return (RD) or assign (WR) the SPI transfer mode.  Use the constants
    SPI_MODE_0..SPI_MODE_3; or if you prefer you can combine SPI_CPOL
    (clock polarity, idle high iff this is set) or SPI_CPHA (clock phase,
    sample on trailing edge iff this is set) flags.
    Note that this request is limited to SPI mode flags that fit in a
    single byte.

SPI_IOC_RD_MODE32, SPI_IOC_WR_MODE32 ...
    pass a pointer to a uin32_t
    which will return (RD) or assign (WR) the full SPI transfer mode,
    not limited to the bits that fit in one byte.

SPI_IOC_RD_LSB_FIRST, SPI_IOC_WR_LSB_FIRST ...
    pass a pointer to a byte
    which will return (RD) or assign (WR) the bit justification used to
    transfer SPI words.  Zero indicates MSB-first; other values indicate
    the less common LSB-first encoding.  In both cases the specified value
    is right-justified in each word, so that unused (TX) or undefined (RX)
    bits are in the MSBs.

SPI_IOC_RD_BITS_PER_WORD, SPI_IOC_WR_BITS_PER_WORD ...
    pass a pointer to
    a byte which will return (RD) or assign (WR) the number of bits in
    each SPI transfer word.  The value zero signifies eight bits.

SPI_IOC_RD_MAX_SPEED_HZ, SPI_IOC_WR_MAX_SPEED_HZ ...
    pass a pointer to a
    u32 which will return (RD) or assign (WR) the maximum SPI transfer
    speed, in Hz.  The controller can't necessarily assign that specific
    clock speed.
”h]”jF  )”}”(hhh]”(jK  )”}”(hX•  SPI_IOC_RD_MODE, SPI_IOC_WR_MODE ...
pass a pointer to a byte which will
return (RD) or assign (WR) the SPI transfer mode.  Use the constants
SPI_MODE_0..SPI_MODE_3; or if you prefer you can combine SPI_CPOL
(clock polarity, idle high iff this is set) or SPI_CPHA (clock phase,
sample on trailing edge iff this is set) flags.
Note that this request is limited to SPI mode flags that fit in a
single byte.
”h]”(jQ  )”}”(hŒ$SPI_IOC_RD_MODE, SPI_IOC_WR_MODE ...”h]”hŒ$SPI_IOC_RD_MODE, SPI_IOC_WR_MODE ...”…””}”(hja  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1jP  hŸh¶h Khj]  ubja  )”}”(hhh]”h¸)”}”(hXo  pass a pointer to a byte which will
return (RD) or assign (WR) the SPI transfer mode.  Use the constants
SPI_MODE_0..SPI_MODE_3; or if you prefer you can combine SPI_CPOL
(clock polarity, idle high iff this is set) or SPI_CPHA (clock phase,
sample on trailing edge iff this is set) flags.
Note that this request is limited to SPI mode flags that fit in a
single byte.”h]”hXo  pass a pointer to a byte which will
return (RD) or assign (WR) the SPI transfer mode.  Use the constants
SPI_MODE_0..SPI_MODE_3; or if you prefer you can combine SPI_CPOL
(clock polarity, idle high iff this is set) or SPI_CPHA (clock phase,
sample on trailing edge iff this is set) flags.
Note that this request is limited to SPI mode flags that fit in a
single byte.”…””}”(hjr  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h Kyhjo  ubah}”(h]”h ]”h"]”h$]”h&]”uh1j`  hj]  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1jJ  hŸh¶h KhjZ  ubjK  )”}”(hŒµSPI_IOC_RD_MODE32, SPI_IOC_WR_MODE32 ...
pass a pointer to a uin32_t
which will return (RD) or assign (WR) the full SPI transfer mode,
not limited to the bits that fit in one byte.
”h]”(jQ  )”}”(hŒ(SPI_IOC_RD_MODE32, SPI_IOC_WR_MODE32 ...”h]”hŒ(SPI_IOC_RD_MODE32, SPI_IOC_WR_MODE32 ...”…””}”(hj  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1jP  hŸh¶h K„hjŒ  ubja  )”}”(hhh]”h¸)”}”(hŒ‹pass a pointer to a uin32_t
which will return (RD) or assign (WR) the full SPI transfer mode,
not limited to the bits that fit in one byte.”h]”hŒ‹pass a pointer to a uin32_t
which will return (RD) or assign (WR) the full SPI transfer mode,
not limited to the bits that fit in one byte.”…””}”(hj¡  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h K‚hjž  ubah}”(h]”h ]”h"]”h$]”h&]”uh1j`  hjŒ  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1jJ  hŸh¶h K„hjZ  ubjK  )”}”(hXu  SPI_IOC_RD_LSB_FIRST, SPI_IOC_WR_LSB_FIRST ...
pass a pointer to a byte
which will return (RD) or assign (WR) the bit justification used to
transfer SPI words.  Zero indicates MSB-first; other values indicate
the less common LSB-first encoding.  In both cases the specified value
is right-justified in each word, so that unused (TX) or undefined (RX)
bits are in the MSBs.
”h]”(jQ  )”}”(hŒ.SPI_IOC_RD_LSB_FIRST, SPI_IOC_WR_LSB_FIRST ...”h]”hŒ.SPI_IOC_RD_LSB_FIRST, SPI_IOC_WR_LSB_FIRST ...”…””}”(hj¿  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1jP  hŸh¶h KŒhj»  ubja  )”}”(hhh]”h¸)”}”(hXE  pass a pointer to a byte
which will return (RD) or assign (WR) the bit justification used to
transfer SPI words.  Zero indicates MSB-first; other values indicate
the less common LSB-first encoding.  In both cases the specified value
is right-justified in each word, so that unused (TX) or undefined (RX)
bits are in the MSBs.”h]”hXE  pass a pointer to a byte
which will return (RD) or assign (WR) the bit justification used to
transfer SPI words.  Zero indicates MSB-first; other values indicate
the less common LSB-first encoding.  In both cases the specified value
is right-justified in each word, so that unused (TX) or undefined (RX)
bits are in the MSBs.”…””}”(hjÐ  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h K‡hjÍ  ubah}”(h]”h ]”h"]”h$]”h&]”uh1j`  hj»  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1jJ  hŸh¶h KŒhjZ  ubjK  )”}”(hŒÊSPI_IOC_RD_BITS_PER_WORD, SPI_IOC_WR_BITS_PER_WORD ...
pass a pointer to
a byte which will return (RD) or assign (WR) the number of bits in
each SPI transfer word.  The value zero signifies eight bits.
”h]”(jQ  )”}”(hŒ6SPI_IOC_RD_BITS_PER_WORD, SPI_IOC_WR_BITS_PER_WORD ...”h]”hŒ6SPI_IOC_RD_BITS_PER_WORD, SPI_IOC_WR_BITS_PER_WORD ...”…””}”(hjî  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1jP  hŸh¶h K‘hjê  ubja  )”}”(hhh]”h¸)”}”(hŒ’pass a pointer to
a byte which will return (RD) or assign (WR) the number of bits in
each SPI transfer word.  The value zero signifies eight bits.”h]”hŒ’pass a pointer to
a byte which will return (RD) or assign (WR) the number of bits in
each SPI transfer word.  The value zero signifies eight bits.”…””}”(hjÿ  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h Khjü  ubah}”(h]”h ]”h"]”h$]”h&]”uh1j`  hjê  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1jJ  hŸh¶h K‘hjZ  ubjK  )”}”(hŒÞSPI_IOC_RD_MAX_SPEED_HZ, SPI_IOC_WR_MAX_SPEED_HZ ...
pass a pointer to a
u32 which will return (RD) or assign (WR) the maximum SPI transfer
speed, in Hz.  The controller can't necessarily assign that specific
clock speed.
”h]”(jQ  )”}”(hŒ4SPI_IOC_RD_MAX_SPEED_HZ, SPI_IOC_WR_MAX_SPEED_HZ ...”h]”hŒ4SPI_IOC_RD_MAX_SPEED_HZ, SPI_IOC_WR_MAX_SPEED_HZ ...”…””}”(hj  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1jP  hŸh¶h K—hj  ubja  )”}”(hhh]”h¸)”}”(hŒ¨pass a pointer to a
u32 which will return (RD) or assign (WR) the maximum SPI transfer
speed, in Hz.  The controller can't necessarily assign that specific
clock speed.”h]”hŒªpass a pointer to a
u32 which will return (RD) or assign (WR) the maximum SPI transfer
speed, in Hz.  The controller canâ€™t necessarily assign that specific
clock speed.”…””}”(hj.  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h K”hj+  ubah}”(h]”h ]”h"]”h$]”h&]”uh1j`  hj  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1jJ  hŸh¶h K—hjZ  ubeh}”(h]”h ]”h"]”h$]”h&]”uh1jE  hjV  ubah}”(h]”h ]”h"]”h$]”h&]”uh1hçhŸh¶h Kxhj  hžhubh¸)”}”(hŒNOTES:”h]”hŒNOTES:”…””}”(hjT  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h K™hj  hžhubhè)”}”(hXê  - At this time there is no async I/O support; everything is purely
  synchronous.

- There's currently no way to report the actual bit rate used to
  shift data to/from a given device.

- From userspace, you can't currently change the chip select polarity;
  that could corrupt transfers to other devices sharing the SPI bus.
  Each SPI device is deselected when it's not in active use, allowing
  other drivers to talk to other devices.

- There's a limit on the number of bytes each I/O request can transfer
  to the SPI device.  It defaults to one page, but that can be changed
  using a module parameter.

- Because SPI has no low-level transfer acknowledgement, you usually
  won't see any I/O errors when talking to a non-existent device.

”h]”hî)”}”(hhh]”(hó)”}”(hŒNAt this time there is no async I/O support; everything is purely
synchronous.
”h]”h¸)”}”(hŒMAt this time there is no async I/O support; everything is purely
synchronous.”h]”hŒMAt this time there is no async I/O support; everything is purely
synchronous.”…””}”(hjm  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h K›hji  ubah}”(h]”h ]”h"]”h$]”h&]”uh1hòhjf  ubhó)”}”(hŒbThere's currently no way to report the actual bit rate used to
shift data to/from a given device.
”h]”h¸)”}”(hŒaThere's currently no way to report the actual bit rate used to
shift data to/from a given device.”h]”hŒcThereâ€™s currently no way to report the actual bit rate used to
shift data to/from a given device.”…””}”(hj…  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h Kžhj  ubah}”(h]”h ]”h"]”h$]”h&]”uh1hòhjf  ubhó)”}”(hŒôFrom userspace, you can't currently change the chip select polarity;
that could corrupt transfers to other devices sharing the SPI bus.
Each SPI device is deselected when it's not in active use, allowing
other drivers to talk to other devices.
”h]”h¸)”}”(hŒóFrom userspace, you can't currently change the chip select polarity;
that could corrupt transfers to other devices sharing the SPI bus.
Each SPI device is deselected when it's not in active use, allowing
other drivers to talk to other devices.”h]”hŒ÷From userspace, you canâ€™t currently change the chip select polarity;
that could corrupt transfers to other devices sharing the SPI bus.
Each SPI device is deselected when itâ€™s not in active use, allowing
other drivers to talk to other devices.”…””}”(hj  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h K¡hj™  ubah}”(h]”h ]”h"]”h$]”h&]”uh1hòhjf  ubhó)”}”(hŒ¤There's a limit on the number of bytes each I/O request can transfer
to the SPI device.  It defaults to one page, but that can be changed
using a module parameter.
”h]”h¸)”}”(hŒ£There's a limit on the number of bytes each I/O request can transfer
to the SPI device.  It defaults to one page, but that can be changed
using a module parameter.”h]”hŒ¥Thereâ€™s a limit on the number of bytes each I/O request can transfer
to the SPI device.  It defaults to one page, but that can be changed
using a module parameter.”…””}”(hjµ  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h K¦hj±  ubah}”(h]”h ]”h"]”h$]”h&]”uh1hòhjf  ubhó)”}”(hŒ„Because SPI has no low-level transfer acknowledgement, you usually
won't see any I/O errors when talking to a non-existent device.

”h]”h¸)”}”(hŒ‚Because SPI has no low-level transfer acknowledgement, you usually
won't see any I/O errors when talking to a non-existent device.”h]”hŒ„Because SPI has no low-level transfer acknowledgement, you usually
wonâ€™t see any I/O errors when talking to a non-existent device.”…””}”(hjÍ  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h KªhjÉ  ubah}”(h]”h ]”h"]”h$]”h&]”uh1hòhjf  ubeh}”(h]”h ]”h"]”h$]”h&]”j*  jÂ  uh1híhŸh¶h K›hjb  ubah}”(h]”h ]”h"]”h$]”h&]”uh1hçhŸh¶h K›hj  hžhubeh}”(h]”Œbasic-character-device-api”ah ]”h"]”Œbasic character device api”ah$]”h&]”uh1h¡hh£hžhhŸh¶h Klubh¢)”}”(hhh]”(h§)”}”(hŒ FULL DUPLEX CHARACTER DEVICE API”h]”hŒ FULL DUPLEX CHARACTER DEVICE API”…””}”(hjø  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h¦hjõ  hžhhŸh¶h K¯ubh¸)”}”(hXg  See the spidev_fdx.c sample program for one example showing the use of the
full duplex programming interface.  (Although it doesn't perform a full duplex
transfer.)  The model is the same as that used in the kernel spi_sync()
request; the individual transfers offer the same capabilities as are
available to kernel drivers (except that it's not asynchronous).”h]”hXk  See the spidev_fdx.c sample program for one example showing the use of the
full duplex programming interface.  (Although it doesnâ€™t perform a full duplex
transfer.)  The model is the same as that used in the kernel spi_sync()
request; the individual transfers offer the same capabilities as are
available to kernel drivers (except that itâ€™s not asynchronous).”…””}”(hj  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h K±hjõ  hžhubh¸)”}”(hXŽ  The example shows one half-duplex RPC-style request and response message.
These requests commonly require that the chip not be deselected between
the request and response.  Several such requests could be chained into
a single kernel request, even allowing the chip to be deselected after
each response.  (Other protocol options include changing the word size
and bitrate for each transfer segment.)”h]”hXŽ  The example shows one half-duplex RPC-style request and response message.
These requests commonly require that the chip not be deselected between
the request and response.  Several such requests could be chained into
a single kernel request, even allowing the chip to be deselected after
each response.  (Other protocol options include changing the word size
and bitrate for each transfer segment.)”…””}”(hj  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h K·hjõ  hžhubh¸)”}”(hŒ€To make a full duplex request, provide both rx_buf and tx_buf for the
same transfer.  It's even OK if those are the same buffer.”h]”hŒ‚To make a full duplex request, provide both rx_buf and tx_buf for the
same transfer.  Itâ€™s even OK if those are the same buffer.”…””}”(hj"  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h K¾hjõ  hžhubeh}”(h]”Œ full-duplex-character-device-api”ah ]”h"]”Œ full duplex character device api”ah$]”h&]”uh1h¡hh£hžhhŸh¶h K¯ubeh}”(h]”Œspi-userspace-api”ah ]”h"]”Œspi userspace api”ah$]”h&]”uh1h¡hhhžhhŸh¶h Kubeh}”(h]”h ]”h"]”h$]”h&]”Œsource”h¶uh1hŒcurrent_source”NŒcurrent_line”NŒsettings”Œdocutils.frontend”ŒValues”“”)”}”(h¦NŒ	generator”NŒ	datestamp”NŒsource_link”NŒ
source_url”NŒtoc_backlinks”Œentry”Œfootnote_backlinks”KŒsectnum_xform”KŒstrip_comments”NŒstrip_elements_with_classes”NŒstrip_classes”NŒreport_level”KŒ
halt_level”KŒexit_status_level”KŒdebug”NŒwarning_stream”NŒ	traceback”ˆŒinput_encoding”Œ	utf-8-sig”Œinput_encoding_error_handler”Œstrict”Œoutput_encoding”Œutf-8”Œoutput_encoding_error_handler”jc  Œerror_encoding”Œutf-8”Œerror_encoding_error_handler”Œbackslashreplace”Œlanguage_code”Œen”Œrecord_dependencies”NŒconfig”NŒ	id_prefix”hŒauto_id_prefix”Œid”Œdump_settings”NŒdump_internals”NŒdump_transforms”NŒdump_pseudo_xml”NŒexpose_internals”NŒstrict_visitor”NŒ_disable_config”NŒ_source”h¶Œ_destination”NŒ_config_files”]”Œ7/var/lib/git/docbuild/linux/Documentation/docutils.conf”aŒfile_insertion_enabled”ˆŒraw_enabled”KŒline_length_limit”M'Œpep_references”NŒpep_base_url”Œhttps://peps.python.org/”Œpep_file_url_template”Œpep-%04d”Œrfc_references”NŒrfc_base_url”Œ&https://datatracker.ietf.org/doc/html/”Œ	tab_width”KŒtrim_footnote_reference_space”‰Œsyntax_highlight”Œlong”Œsmart_quotes”ˆŒsmartquotes_locales”]”Œcharacter_level_inline_markup”‰Œdoctitle_xform”‰Œdocinfo_xform”KŒsectsubtitle_xform”‰Œimage_loading”Œlink”Œembed_stylesheet”‰Œcloak_email_addresses”ˆŒsection_self_link”‰Œenv”NubŒreporter”NŒindirect_targets”]”Œsubstitution_defs”}”Œsubstitution_names”}”Œrefnames”}”Œrefids”}”Œnameids”}”(j=  j:  j  j  jò  jï  j5  j2  uŒ	nametypes”}”(j=  ‰j  ‰jò  ‰j5  ‰uh}”(j:  h£j  j@  jï  j  j2  jõ  uŒfootnote_refs”}”Œcitation_refs”}”Œautofootnotes”]”Œautofootnote_refs”]”Œsymbol_footnotes”]”Œsymbol_footnote_refs”]”Œ	footnotes”]”Œ	citations”]”Œautofootnote_start”KŒsymbol_footnote_start”K Œ
id_counter”Œcollections”ŒCounter”“”}”…”R”Œparse_messages”]”Œtransform_messages”]”Œtransformer”NŒinclude_log”]”Œ
decoration”Nhžhub.