€•3F      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)”…””}”(hhŒparent”hubaŒ
attributes”}”(Œids”]”Œclasses”]”Œnames”]”Œdupnames”]”Œbackrefs”]”Œ	refdomain”Œstd”Œreftype”Œdoc”Œ	reftarget”Œ"/translations/zh_CN/driver-api/isa”Œmodname”NŒ	classname”NŒrefexplicit”ˆuŒtagname”hhhubh)”}”(hhh]”hŒChinese (Traditional)”…””}”(hhhh2ubah}”(h]”h ]”h"]”h$]”h&]”Œ	refdomain”h)Œreftype”h+Œ	reftarget”Œ"/translations/zh_TW/driver-api/isa”Œmodname”NŒ	classname”NŒrefexplicit”ˆuh1hhhubh)”}”(hhh]”hŒItalian”…””}”(hhhhFubah}”(h]”h ]”h"]”h$]”h&]”Œ	refdomain”h)Œreftype”h+Œ	reftarget”Œ"/translations/it_IT/driver-api/isa”Œmodname”NŒ	classname”NŒrefexplicit”ˆuh1hhhubh)”}”(hhh]”hŒJapanese”…””}”(hhhhZubah}”(h]”h ]”h"]”h$]”h&]”Œ	refdomain”h)Œreftype”h+Œ	reftarget”Œ"/translations/ja_JP/driver-api/isa”Œmodname”NŒ	classname”NŒrefexplicit”ˆuh1hhhubh)”}”(hhh]”hŒKorean”…””}”(hhhhnubah}”(h]”h ]”h"]”h$]”h&]”Œ	refdomain”h)Œreftype”h+Œ	reftarget”Œ"/translations/ko_KR/driver-api/isa”Œmodname”NŒ	classname”NŒrefexplicit”ˆuh1hhhubh)”}”(hhh]”hŒSpanish”…””}”(hhhh‚ubah}”(h]”h ]”h"]”h$]”h&]”Œ	refdomain”h)Œreftype”h+Œ	reftarget”Œ"/translations/sp_SP/driver-api/isa”Œmodname”NŒ	classname”NŒrefexplicit”ˆuh1hhhubeh}”(h]”h ]”h"]”h$]”h&]”Œcurrent_language”ŒEnglish”uh1h
hhŒ	_document”hŒsource”NŒline”NubhŒsection”“”)”}”(hhh]”(hŒtitle”“”)”}”(hŒISA Drivers”h]”hŒISA Drivers”…””}”(hhªhh¨hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h¦hh£hžhhŸŒ</var/lib/git/docbuild/linux/Documentation/driver-api/isa.rst”h KubhŒ	paragraph”“”)”}”(hŒzThe following text is adapted from the commit message of the initial
commit of the ISA bus driver authored by Rene Herman.”h]”hŒzThe following text is adapted from the commit message of the initial
commit of the ISA bus driver authored by Rene Herman.”…””}”(hh»hh¹hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h Khh£hžhubh¸)”}”(hXß  During the recent "isa drivers using platform devices" discussion it was
pointed out that (ALSA) ISA drivers ran into the problem of not having
the option to fail driver load (device registration rather) upon not
finding their hardware due to a probe() error not being passed up
through the driver model. In the course of that, I suggested a separate
ISA bus might be best; Russell King agreed and suggested this bus could
use the .match() method for the actual device discovery.”h]”hXã  During the recent â€œisa drivers using platform devicesâ€ discussion it was
pointed out that (ALSA) ISA drivers ran into the problem of not having
the option to fail driver load (device registration rather) upon not
finding their hardware due to a probe() error not being passed up
through the driver model. In the course of that, I suggested a separate
ISA bus might be best; Russell King agreed and suggested this bus could
use the .match() method for the actual device discovery.”…””}”(hhÉhhÇhžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h Khh£hžhubh¸)”}”(hŒÚThe attached does this. For this old non (generically) discoverable ISA
hardware only the driver itself can do discovery so as a difference with
the platform_bus, this isa_bus also distributes match() up to the
driver.”h]”hŒÚThe attached does this. For this old non (generically) discoverable ISA
hardware only the driver itself can do discovery so as a difference with
the platform_bus, this isa_bus also distributes match() up to the
driver.”…””}”(hh×hhÕhžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h Khh£hžhubh¸)”}”(hŒÉAs another difference: these devices only exist in the driver model due
to the driver creating them because it might want to drive them, meaning
that all device creation has been made internal as well.”h]”hŒÉAs another difference: these devices only exist in the driver model due
to the driver creating them because it might want to drive them, meaning
that all device creation has been made internal as well.”…””}”(hhåhhãhžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h Khh£hžhubh¸)”}”(hŒ¶The usage model this provides is nice, and has been acked from the ALSA
side by Takashi Iwai and Jaroslav Kysela. The ALSA driver module_init's
now (for oldisa-only drivers) become::”h]”hŒ·The usage model this provides is nice, and has been acked from the ALSA
side by Takashi Iwai and Jaroslav Kysela. The ALSA driver module_initâ€™s
now (for oldisa-only drivers) become:”…””}”(hŒµThe usage model this provides is nice, and has been acked from the ALSA
side by Takashi Iwai and Jaroslav Kysela. The ALSA driver module_init's
now (for oldisa-only drivers) become:”hhñhžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h Khh£hžhubhŒliteral_block”“”)”}”(hŒÙstatic int __init alsa_card_foo_init(void)
{
        return isa_register_driver(&snd_foo_isa_driver, SNDRV_CARDS);
}

static void __exit alsa_card_foo_exit(void)
{
        isa_unregister_driver(&snd_foo_isa_driver);
}”h]”hŒÙstatic int __init alsa_card_foo_init(void)
{
        return isa_register_driver(&snd_foo_isa_driver, SNDRV_CARDS);
}

static void __exit alsa_card_foo_exit(void)
{
        isa_unregister_driver(&snd_foo_isa_driver);
}”…””}”(hhhj  ubah}”(h]”h ]”h"]”h$]”h&]”Œ	xml:space”Œpreserve”uh1j   hŸh¶h Khh£hžhubh¸)”}”(hŒpQuite like the other bus models therefore. This removes a lot of
duplicated init code from the ALSA ISA drivers.”h]”hŒpQuite like the other bus models therefore. This removes a lot of
duplicated init code from the ALSA ISA drivers.”…””}”(hj  hj  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h K'hh£hžhubh¸)”}”(hŒÀThe passed in isa_driver struct is the regular driver struct embedding a
struct device_driver, the normal probe/remove/shutdown/suspend/resume
callbacks, and as indicated that .match callback.”h]”hŒÀThe passed in isa_driver struct is the regular driver struct embedding a
struct device_driver, the normal probe/remove/shutdown/suspend/resume
callbacks, and as indicated that .match callback.”…””}”(hj"  hj   hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h K*hh£hžhubh¸)”}”(hŒŽThe "SNDRV_CARDS" you see being passed in is a "unsigned int ndev"
parameter, indicating how many devices to create and call our methods
with.”h]”hŒ–The â€œSNDRV_CARDSâ€ you see being passed in is a â€œunsigned int ndevâ€
parameter, indicating how many devices to create and call our methods
with.”…””}”(hj0  hj.  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h K.hh£hžhubh¸)”}”(hX­  The platform_driver callbacks are called with a platform_device param;
the isa_driver callbacks are being called with a ``struct device *dev,
unsigned int id`` pair directly -- with the device creation completely
internal to the bus it's much cleaner to not leak isa_dev's by passing
them in at all. The id is the only thing we ever want other then the
struct device anyways, and it makes for nicer code in the callbacks as
well.”h]”(hŒxThe platform_driver callbacks are called with a platform_device param;
the isa_driver callbacks are being called with a ”…””}”(hŒxThe platform_driver callbacks are called with a platform_device param;
the isa_driver callbacks are being called with a ”hj<  hžhhŸNh NubhŒliteral”“”)”}”(hŒ'``struct device *dev,
unsigned int id``”h]”hŒ#struct device *dev,
unsigned int id”…””}”(hhhjG  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1jE  hj<  ubhX   pair directly -- with the device creation completely
internal to the bus itâ€™s much cleaner to not leak isa_devâ€™s by passing
them in at all. The id is the only thing we ever want other then the
struct device anyways, and it makes for nicer code in the callbacks as
well.”…””}”(hX   pair directly -- with the device creation completely
internal to the bus it's much cleaner to not leak isa_dev's by passing
them in at all. The id is the only thing we ever want other then the
struct device anyways, and it makes for nicer code in the callbacks as
well.”hj<  hžhhŸNh Nubeh}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h K2hh£hžhubh¸)”}”(hXÔ  With this additional .match() callback ISA drivers have all options. If
ALSA would want to keep the old non-load behaviour, it could stick all
of the old .probe in .match, which would only keep them registered after
everything was found to be present and accounted for. If it wanted the
behaviour of always loading as it inadvertently did for a bit after the
changeover to platform devices, it could just not provide a .match() and
do everything in .probe() as before.”h]”hXÔ  With this additional .match() callback ISA drivers have all options. If
ALSA would want to keep the old non-load behaviour, it could stick all
of the old .probe in .match, which would only keep them registered after
everything was found to be present and accounted for. If it wanted the
behaviour of always loading as it inadvertently did for a bit after the
changeover to platform devices, it could just not provide a .match() and
do everything in .probe() as before.”…””}”(hjb  hj`  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h K:hh£hžhubh¸)”}”(hXv  If it, as Takashi Iwai already suggested earlier as a way of following
the model from saner buses more closely, wants to load when a later bind
could conceivably succeed, it could use .match() for the prerequisites
(such as checking the user wants the card enabled and that port/irq/dma
values have been passed in) and .probe() for everything else. This is
the nicest model.”h]”hXv  If it, as Takashi Iwai already suggested earlier as a way of following
the model from saner buses more closely, wants to load when a later bind
could conceivably succeed, it could use .match() for the prerequisites
(such as checking the user wants the card enabled and that port/irq/dma
values have been passed in) and .probe() for everything else. This is
the nicest model.”…””}”(hjp  hjn  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h KBhh£hžhubh¸)”}”(hŒTo the code...”h]”hŒTo the code...”…””}”(hj~  hj|  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h KIhh£hžhubh¸)”}”(hŒ<This exports only two functions; isa_{,un}register_driver().”h]”hŒ<This exports only two functions; isa_{,un}register_driver().”…””}”(hjŒ  hjŠ  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h KKhh£hžhubh¸)”}”(hŒËisa_register_driver() register's the struct device_driver, and then
loops over the passed in ndev creating devices and registering them.
This causes the bus match method to be called for them, which is::”h]”hŒÌisa_register_driver() registerâ€™s the struct device_driver, and then
loops over the passed in ndev creating devices and registering them.
This causes the bus match method to be called for them, which is:”…””}”(hŒÊisa_register_driver() register's the struct device_driver, and then
loops over the passed in ndev creating devices and registering them.
This causes the bus match method to be called for them, which is:”hj˜  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h KMhh£hžhubj  )”}”(hX  int isa_bus_match(struct device *dev, struct device_driver *driver)
{
        struct isa_driver *isa_driver = to_isa_driver(driver);

        if (dev->platform_data == isa_driver) {
                if (!isa_driver->match ||
                        isa_driver->match(dev, to_isa_dev(dev)->id))
                        return 1;
                dev->platform_data = NULL;
        }
        return 0;
}”h]”hX  int isa_bus_match(struct device *dev, struct device_driver *driver)
{
        struct isa_driver *isa_driver = to_isa_driver(driver);

        if (dev->platform_data == isa_driver) {
                if (!isa_driver->match ||
                        isa_driver->match(dev, to_isa_dev(dev)->id))
                        return 1;
                dev->platform_data = NULL;
        }
        return 0;
}”…””}”(hhhj§  ubah}”(h]”h ]”h"]”h$]”h&]”j  j  uh1j   hŸh¶h KQhh£hžhubh¸)”}”(hX   The first thing this does is check if this device is in fact one of this
driver's devices by seeing if the device's platform_data pointer is set
to this driver. Platform devices compare strings, but we don't need to
do that with everything being internal, so isa_register_driver() abuses
dev->platform_data as a isa_driver pointer which we can then check here.
I believe platform_data is available for this, but if rather not, moving
the isa_driver pointer to the private struct isa_dev is ofcourse fine as
well.”h]”hX  The first thing this does is check if this device is in fact one of this
driverâ€™s devices by seeing if the deviceâ€™s platform_data pointer is set
to this driver. Platform devices compare strings, but we donâ€™t need to
do that with everything being internal, so isa_register_driver() abuses
dev->platform_data as a isa_driver pointer which we can then check here.
I believe platform_data is available for this, but if rather not, moving
the isa_driver pointer to the private struct isa_dev is ofcourse fine as
well.”…””}”(hj·  hjµ  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h K^hh£hžhubh¸)”}”(hŒ~Then, if the driver did not provide a .match, it matches. If it did,
the driver match() method is called to determine a match.”h]”hŒ~Then, if the driver did not provide a .match, it matches. If it did,
the driver match() method is called to determine a match.”…””}”(hjÅ  hjÃ  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h Kghh£hžhubh¸)”}”(hŒˆIf it did **not** match, dev->platform_data is reset to indicate this to
isa_register_driver which can then unregister the device again.”h]”(hŒ
If it did ”…””}”(hŒ
If it did ”hjÑ  hžhhŸNh NubhŒstrong”“”)”}”(hŒ**not**”h]”hŒnot”…””}”(hhhjÜ  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1jÚ  hjÑ  ubhŒw match, dev->platform_data is reset to indicate this to
isa_register_driver which can then unregister the device again.”…””}”(hŒw match, dev->platform_data is reset to indicate this to
isa_register_driver which can then unregister the device again.”hjÑ  hžhhŸNh Nubeh}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h Kjhh£hžhubh¸)”}”(hŒŠIf during all this, there's any error, or no devices matched at all
everything is backed out again and the error, or -ENODEV, is returned.”h]”hŒŒIf during all this, thereâ€™s any error, or no devices matched at all
everything is backed out again and the error, or -ENODEV, is returned.”…””}”(hj÷  hjõ  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h Kmhh£hžhubh¸)”}”(hŒSisa_unregister_driver() just unregisters the matched devices and the
driver itself.”h]”hŒSisa_unregister_driver() just unregisters the matched devices and the
driver itself.”…””}”(hj  hj  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h Kphh£hžhubh¸)”}”(hŒómodule_isa_driver is a helper macro for ISA drivers which do not do
anything special in module init/exit. This eliminates a lot of
boilerplate code. Each module may only use this macro once, and calling
it replaces module_init and module_exit.”h]”hŒómodule_isa_driver is a helper macro for ISA drivers which do not do
anything special in module init/exit. This eliminates a lot of
boilerplate code. Each module may only use this macro once, and calling
it replaces module_init and module_exit.”…””}”(hj  hj  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h Kshh£hžhubh¸)”}”(hŒµmax_num_isa_dev is a macro to determine the maximum possible number of
ISA devices which may be registered in the I/O port address space given
the address extent of the ISA devices.”h]”hŒµmax_num_isa_dev is a macro to determine the maximum possible number of
ISA devices which may be registered in the I/O port address space given
the address extent of the ISA devices.”…””}”(hj!  hj  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h Kxhh£hžhubeh}”(h]”Œisa-drivers”ah ]”h"]”Œisa drivers”ah$]”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”jX  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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file_insertion_enabled”ˆŒraw_enabled”KŒline_length_limit”M'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”‰Œembed_images”‰Œenv”NubŒreporter”NŒindirect_targets”]”Œsubstitution_defs”}”Œsubstitution_names”}”Œrefnames”}”Œrefids”}”Œnameids”}”j2  j/  sŒ	nametypes”}”j2  Nsh}”j/  h£sŒ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.