€•”ž      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/input/input-programming”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$]”h&]”Œ	refdomain”h)Œreftype”h+Œ	reftarget”Œ+/translations/zh_TW/input/input-programming”Œmodname”NŒ	classname”NŒrefexplicit”ˆuh1hhhubh)”}”(hhh]”hŒItalian”…””}”hhFsbah}”(h]”h ]”h"]”h$]”h&]”Œ	refdomain”h)Œreftype”h+Œ	reftarget”Œ+/translations/it_IT/input/input-programming”Œmodname”NŒ	classname”NŒrefexplicit”ˆuh1hhhubh)”}”(hhh]”hŒJapanese”…””}”hhZsbah}”(h]”h ]”h"]”h$]”h&]”Œ	refdomain”h)Œreftype”h+Œ	reftarget”Œ+/translations/ja_JP/input/input-programming”Œmodname”NŒ	classname”NŒrefexplicit”ˆuh1hhhubh)”}”(hhh]”hŒKorean”…””}”hhnsbah}”(h]”h ]”h"]”h$]”h&]”Œ	refdomain”h)Œreftype”h+Œ	reftarget”Œ+/translations/ko_KR/input/input-programming”Œmodname”NŒ	classname”NŒrefexplicit”ˆuh1hhhubh)”}”(hhh]”hŒPortuguese (Brazilian)”…””}”hh‚sbah}”(h]”h ]”h"]”h$]”h&]”Œ	refdomain”h)Œreftype”h+Œ	reftarget”Œ+/translations/pt_BR/input/input-programming”Œmodname”NŒ	classname”NŒrefexplicit”ˆuh1hhhubh)”}”(hhh]”hŒSpanish”…””}”hh–sbah}”(h]”h ]”h"]”h$]”h&]”Œ	refdomain”h)Œreftype”h+Œ	reftarget”Œ+/translations/sp_SP/input/input-programming”Œmodname”NŒ	classname”NŒrefexplicit”ˆuh1hhhubeh}”(h]”h ]”h"]”h$]”h&]”Œcurrent_language”ŒEnglish”uh1h
hhŒ	_document”hŒsource”NŒline”NubhŒsection”“”)”}”(hhh]”(hŒtitle”“”)”}”(hŒCreating an input device driver”h]”hŒCreating an input device driver”…””}”(hh¼h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hºhh·h²hh³ŒE/var/lib/git/docbuild/linux/Documentation/input/input-programming.rst”h´Kubh¶)”}”(hhh]”(h»)”}”(hŒThe simplest example”h]”hŒThe simplest example”…””}”(hhÎh²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hºhhËh²hh³hÊh´KubhŒ	paragraph”“”)”}”(hŒÜHere comes a very simple example of an input device driver. The device has
just one button and the button is accessible at i/o port BUTTON_PORT. When
pressed or released a BUTTON_IRQ happens. The driver could look like::”h]”hŒÛHere comes a very simple example of an input device driver. The device has
just one button and the button is accessible at i/o port BUTTON_PORT. When
pressed or released a BUTTON_IRQ happens. The driver could look like:”…””}”(hhÞh²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÜh³hÊh´KhhËh²hubhŒliteral_block”“”)”}”(hXÀ  #include <linux/input.h>
#include <linux/module.h>
#include <linux/init.h>

#include <asm/irq.h>
#include <asm/io.h>

static struct input_dev *button_dev;

static irqreturn_t button_interrupt(int irq, void *dummy)
{
        input_report_key(button_dev, BTN_0, inb(BUTTON_PORT) & 1);
        input_sync(button_dev);
        return IRQ_HANDLED;
}

static int __init button_init(void)
{
        int error;

        if (request_irq(BUTTON_IRQ, button_interrupt, 0, "button", NULL)) {
                printk(KERN_ERR "button.c: Can't allocate irq %d\n", button_irq);
                return -EBUSY;
        }

        button_dev = input_allocate_device();
        if (!button_dev) {
                printk(KERN_ERR "button.c: Not enough memory\n");
                error = -ENOMEM;
                goto err_free_irq;
        }

        button_dev->evbit[0] = BIT_MASK(EV_KEY);
        button_dev->keybit[BIT_WORD(BTN_0)] = BIT_MASK(BTN_0);

        error = input_register_device(button_dev);
        if (error) {
                printk(KERN_ERR "button.c: Failed to register device\n");
                goto err_free_dev;
        }

        return 0;

err_free_dev:
        input_free_device(button_dev);
err_free_irq:
        free_irq(BUTTON_IRQ, button_interrupt);
        return error;
}

static void __exit button_exit(void)
{
        input_unregister_device(button_dev);
        free_irq(BUTTON_IRQ, button_interrupt);
}

module_init(button_init);
module_exit(button_exit);”h]”hXÀ  #include <linux/input.h>
#include <linux/module.h>
#include <linux/init.h>

#include <asm/irq.h>
#include <asm/io.h>

static struct input_dev *button_dev;

static irqreturn_t button_interrupt(int irq, void *dummy)
{
        input_report_key(button_dev, BTN_0, inb(BUTTON_PORT) & 1);
        input_sync(button_dev);
        return IRQ_HANDLED;
}

static int __init button_init(void)
{
        int error;

        if (request_irq(BUTTON_IRQ, button_interrupt, 0, "button", NULL)) {
                printk(KERN_ERR "button.c: Can't allocate irq %d\n", button_irq);
                return -EBUSY;
        }

        button_dev = input_allocate_device();
        if (!button_dev) {
                printk(KERN_ERR "button.c: Not enough memory\n");
                error = -ENOMEM;
                goto err_free_irq;
        }

        button_dev->evbit[0] = BIT_MASK(EV_KEY);
        button_dev->keybit[BIT_WORD(BTN_0)] = BIT_MASK(BTN_0);

        error = input_register_device(button_dev);
        if (error) {
                printk(KERN_ERR "button.c: Failed to register device\n");
                goto err_free_dev;
        }

        return 0;

err_free_dev:
        input_free_device(button_dev);
err_free_irq:
        free_irq(BUTTON_IRQ, button_interrupt);
        return error;
}

static void __exit button_exit(void)
{
        input_unregister_device(button_dev);
        free_irq(BUTTON_IRQ, button_interrupt);
}

module_init(button_init);
module_exit(button_exit);”…””}”hhîsbah}”(h]”h ]”h"]”h$]”h&]”Œ	xml:space”Œpreserve”uh1hìh³hÊh´KhhËh²hubeh}”(h]”Œthe-simplest-example”ah ]”h"]”Œthe simplest example”ah$]”h&]”uh1hµhh·h²hh³hÊh´Kubh¶)”}”(hhh]”(h»)”}”(hŒWhat the example does”h]”hŒWhat the example does”…””}”(hj	  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hºhj  h²hh³hÊh´KHubhÝ)”}”(hŒ„First it has to include the <linux/input.h> file, which interfaces to the
input subsystem. This provides all the definitions needed.”h]”hŒ„First it has to include the <linux/input.h> file, which interfaces to the
input subsystem. This provides all the definitions needed.”…””}”(hj  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÜh³hÊh´KJhj  h²hubhÝ)”}”(hŒ±In the _init function, which is called either upon module load or when
booting the kernel, it grabs the required resources (it should also check
for the presence of the device).”h]”hŒ±In the _init function, which is called either upon module load or when
booting the kernel, it grabs the required resources (it should also check
for the presence of the device).”…””}”(hj%  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÜh³hÊh´KMhj  h²hubhÝ)”}”(hX  Then it allocates a new input device structure with input_allocate_device()
and sets up input bitfields. This way the device driver tells the other
parts of the input systems what it is - what events can be generated or
accepted by this input device. Our example device can only generate EV_KEY
type events, and from those only BTN_0 event code. Thus we only set these
two bits. We could have used::”h]”hXŽ  Then it allocates a new input device structure with input_allocate_device()
and sets up input bitfields. This way the device driver tells the other
parts of the input systems what it is - what events can be generated or
accepted by this input device. Our example device can only generate EV_KEY
type events, and from those only BTN_0 event code. Thus we only set these
two bits. We could have used:”…””}”(hj3  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÜh³hÊh´KQhj  h²hubhí)”}”(hŒGset_bit(EV_KEY, button_dev->evbit);
set_bit(BTN_0, button_dev->keybit);”h]”hŒGset_bit(EV_KEY, button_dev->evbit);
set_bit(BTN_0, button_dev->keybit);”…””}”hjA  sbah}”(h]”h ]”h"]”h$]”h&]”hühýuh1hìh³hÊh´KXhj  h²hubhÝ)”}”(hŒOas well, but with more than single bits the first approach tends to be
shorter.”h]”hŒOas well, but with more than single bits the first approach tends to be
shorter.”…””}”(hjO  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÜh³hÊh´K[hj  h²hubhÝ)”}”(hŒIThen the example driver registers the input device structure by calling::”h]”hŒHThen the example driver registers the input device structure by calling:”…””}”(hj]  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÜh³hÊh´K^hj  h²hubhí)”}”(hŒ"input_register_device(button_dev);”h]”hŒ"input_register_device(button_dev);”…””}”hjk  sbah}”(h]”h ]”h"]”h$]”h&]”hühýuh1hìh³hÊh´K`hj  h²hubhÝ)”}”(hX  This adds the button_dev structure to linked lists of the input driver and
calls device handler modules _connect functions to tell them a new input
device has appeared. input_register_device() may sleep and therefore must
not be called from an interrupt or with a spinlock held.”h]”hX  This adds the button_dev structure to linked lists of the input driver and
calls device handler modules _connect functions to tell them a new input
device has appeared. input_register_device() may sleep and therefore must
not be called from an interrupt or with a spinlock held.”…””}”(hjy  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÜh³hÊh´Kbhj  h²hubhÝ)”}”(hŒ7While in use, the only used function of the driver is::”h]”hŒ6While in use, the only used function of the driver is:”…””}”(hj‡  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÜh³hÊh´Kghj  h²hubhí)”}”(hŒbutton_interrupt()”h]”hŒbutton_interrupt()”…””}”hj•  sbah}”(h]”h ]”h"]”h$]”h&]”hühýuh1hìh³hÊh´Kihj  h²hubhÝ)”}”(hŒTwhich upon every interrupt from the button checks its state and reports it
via the::”h]”hŒSwhich upon every interrupt from the button checks its state and reports it
via the:”…””}”(hj£  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÜh³hÊh´Kkhj  h²hubhí)”}”(hŒinput_report_key()”h]”hŒinput_report_key()”…””}”hj±  sbah}”(h]”h ]”h"]”h$]”h&]”hühýuh1hìh³hÊh´Knhj  h²hubhÝ)”}”(hŒãcall to the input system. There is no need to check whether the interrupt
routine isn't reporting two same value events (press, press for example) to
the input system, because the input_report_* functions check that
themselves.”h]”hŒåcall to the input system. There is no need to check whether the interrupt
routine isnâ€™t reporting two same value events (press, press for example) to
the input system, because the input_report_* functions check that
themselves.”…””}”(hj¿  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÜh³hÊh´Kphj  h²hubhÝ)”}”(hŒThen there is the::”h]”hŒThen there is the:”…””}”(hjÍ  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÜh³hÊh´Kuhj  h²hubhí)”}”(hŒinput_sync()”h]”hŒinput_sync()”…””}”hjÛ  sbah}”(h]”h ]”h"]”h$]”h&]”hühýuh1hìh³hÊh´Kwhj  h²hubhÝ)”}”(hX,  call to tell those who receive the events that we've sent a complete report.
This doesn't seem important in the one button case, but is quite important
for example for mouse movement, where you don't want the X and Y values
to be interpreted separately, because that'd result in a different movement.”h]”hX4  call to tell those who receive the events that weâ€™ve sent a complete report.
This doesnâ€™t seem important in the one button case, but is quite important
for example for mouse movement, where you donâ€™t want the X and Y values
to be interpreted separately, because thatâ€™d result in a different movement.”…””}”(hjé  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÜh³hÊh´Kyhj  h²hubeh}”(h]”Œwhat-the-example-does”ah ]”h"]”Œwhat the example does”ah$]”h&]”uh1hµhh·h²hh³hÊh´KHubh¶)”}”(hhh]”(h»)”}”(hŒdev->open() and dev->close()”h]”hŒdev->open() and dev->close()”…””}”(hj  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hºhjÿ  h²hh³hÊh´KubhÝ)”}”(hX³  In case the driver has to repeatedly poll the device, because it doesn't
have an interrupt coming from it and the polling is too expensive to be done
all the time, or if the device uses a valuable resource (e.g. interrupt), it
can use the open and close callback to know when it can stop polling or
release the interrupt and when it must resume polling or grab the interrupt
again. To do that, we would add this to our example driver::”h]”hX´  In case the driver has to repeatedly poll the device, because it doesnâ€™t
have an interrupt coming from it and the polling is too expensive to be done
all the time, or if the device uses a valuable resource (e.g. interrupt), it
can use the open and close callback to know when it can stop polling or
release the interrupt and when it must resume polling or grab the interrupt
again. To do that, we would add this to our example driver:”…””}”(hj  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÜh³hÊh´Khjÿ  h²hubhí)”}”(hX  static int button_open(struct input_dev *dev)
{
        if (request_irq(BUTTON_IRQ, button_interrupt, 0, "button", NULL)) {
                printk(KERN_ERR "button.c: Can't allocate irq %d\n", button_irq);
                return -EBUSY;
        }

        return 0;
}

static void button_close(struct input_dev *dev)
{
        free_irq(IRQ_AMIGA_VERTB, button_interrupt);
}

static int __init button_init(void)
{
        ...
        button_dev->open = button_open;
        button_dev->close = button_close;
        ...
}”h]”hX  static int button_open(struct input_dev *dev)
{
        if (request_irq(BUTTON_IRQ, button_interrupt, 0, "button", NULL)) {
                printk(KERN_ERR "button.c: Can't allocate irq %d\n", button_irq);
                return -EBUSY;
        }

        return 0;
}

static void button_close(struct input_dev *dev)
{
        free_irq(IRQ_AMIGA_VERTB, button_interrupt);
}

static int __init button_init(void)
{
        ...
        button_dev->open = button_open;
        button_dev->close = button_close;
        ...
}”…””}”hj  sbah}”(h]”h ]”h"]”h$]”h&]”hühýuh1hìh³hÊh´Kˆhjÿ  h²hubhÝ)”}”(hX	  Note that input core keeps track of number of users for the device and
makes sure that dev->open() is called only when the first user connects
to the device and that dev->close() is called when the very last user
disconnects. Calls to both callbacks are serialized.”h]”hX	  Note that input core keeps track of number of users for the device and
makes sure that dev->open() is called only when the first user connects
to the device and that dev->close() is called when the very last user
disconnects. Calls to both callbacks are serialized.”…””}”(hj,  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÜh³hÊh´KŸhjÿ  h²hubhÝ)”}”(hŒœThe open() callback should return a 0 in case of success or any non-zero value
in case of failure. The close() callback (which is void) must always succeed.”h]”hŒœThe open() callback should return a 0 in case of success or any non-zero value
in case of failure. The close() callback (which is void) must always succeed.”…””}”(hj:  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÜh³hÊh´K¤hjÿ  h²hubeh}”(h]”Œdev-open-and-dev-close”ah ]”h"]”Œdev->open() and dev->close()”ah$]”h&]”uh1hµhh·h²hh³hÊh´Kubh¶)”}”(hhh]”(h»)”}”(hŒInhibiting input devices”h]”hŒInhibiting input devices”…””}”(hjS  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hºhjP  h²hh³hÊh´K¨ubhÝ)”}”(hŒîInhibiting a device means ignoring input events from it. As such it is about
maintaining relationships with input handlers - either already existing
relationships, or relationships to be established while the device is in
inhibited state.”h]”hŒîInhibiting a device means ignoring input events from it. As such it is about
maintaining relationships with input handlers - either already existing
relationships, or relationships to be established while the device is in
inhibited state.”…””}”(hja  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÜh³hÊh´KªhjP  h²hubhÝ)”}”(hŒGIf a device is inhibited, no input handler will receive events from it.”h]”hŒGIf a device is inhibited, no input handler will receive events from it.”…””}”(hjo  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÜh³hÊh´K¯hjP  h²hubhÝ)”}”(hX[  The fact that nobody wants events from the device is exploited further, by
calling device's close() (if there are users) and open() (if there are users) on
inhibit and uninhibit operations, respectively. Indeed, the meaning of close()
is to stop providing events to the input core and that of open() is to start
providing events to the input core.”h]”hX]  The fact that nobody wants events from the device is exploited further, by
calling deviceâ€™s close() (if there are users) and open() (if there are users) on
inhibit and uninhibit operations, respectively. Indeed, the meaning of close()
is to stop providing events to the input core and that of open() is to start
providing events to the input core.”…””}”(hj}  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÜh³hÊh´K±hjP  h²hubhÝ)”}”(hŒïCalling the device's close() method on inhibit (if there are users) allows the
driver to save power. Either by directly powering down the device or by
releasing the runtime-PM reference it got in open() when the driver is using
runtime-PM.”h]”hŒñCalling the deviceâ€™s close() method on inhibit (if there are users) allows the
driver to save power. Either by directly powering down the device or by
releasing the runtime-PM reference it got in open() when the driver is using
runtime-PM.”…””}”(hj‹  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÜh³hÊh´K·hjP  h²hubhÝ)”}”(hŒÍInhibiting and uninhibiting are orthogonal to opening and closing the device by
input handlers. Userspace might want to inhibit a device in anticipation before
any handler is positively matched against it.”h]”hŒÍInhibiting and uninhibiting are orthogonal to opening and closing the device by
input handlers. Userspace might want to inhibit a device in anticipation before
any handler is positively matched against it.”…””}”(hj™  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÜh³hÊh´K¼hjP  h²hubhÝ)”}”(hX-  Inhibiting and uninhibiting are orthogonal to device's being a wakeup source,
too. Being a wakeup source plays a role when the system is sleeping, not when
the system is operating.  How drivers should program their interaction between
inhibiting, sleeping and being a wakeup source is driver-specific.”h]”hX/  Inhibiting and uninhibiting are orthogonal to deviceâ€™s being a wakeup source,
too. Being a wakeup source plays a role when the system is sleeping, not when
the system is operating.  How drivers should program their interaction between
inhibiting, sleeping and being a wakeup source is driver-specific.”…””}”(hj§  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÜh³hÊh´KÀhjP  h²hubhÝ)”}”(hX‹  Taking the analogy with the network devices - bringing a network interface down
doesn't mean that it should be impossible be wake the system up on LAN through
this interface. So, there may be input drivers which should be considered wakeup
sources even when inhibited. Actually, in many I2C input devices their interrupt
is declared a wakeup interrupt and its handling happens in driver's core, which
is not aware of input-specific inhibit (nor should it be).  Composite devices
containing several interfaces can be inhibited on a per-interface basis and e.g.
inhibiting one interface shouldn't affect the device's capability of being a
wakeup source.”h]”hX“  Taking the analogy with the network devices - bringing a network interface down
doesnâ€™t mean that it should be impossible be wake the system up on LAN through
this interface. So, there may be input drivers which should be considered wakeup
sources even when inhibited. Actually, in many I2C input devices their interrupt
is declared a wakeup interrupt and its handling happens in driverâ€™s core, which
is not aware of input-specific inhibit (nor should it be).  Composite devices
containing several interfaces can be inhibited on a per-interface basis and e.g.
inhibiting one interface shouldnâ€™t affect the deviceâ€™s capability of being a
wakeup source.”…””}”(hjµ  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÜh³hÊh´KÅhjP  h²hubhÝ)”}”(hXd  If a device is to be considered a wakeup source while inhibited, special care
must be taken when programming its suspend(), as it might need to call device's
open(). Depending on what close() means for the device in question, not
opening() it before going to sleep might make it impossible to provide any
wakeup events. The device is going to sleep anyway.”h]”hXf  If a device is to be considered a wakeup source while inhibited, special care
must be taken when programming its suspend(), as it might need to call deviceâ€™s
open(). Depending on what close() means for the device in question, not
opening() it before going to sleep might make it impossible to provide any
wakeup events. The device is going to sleep anyway.”…””}”(hjÃ  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÜh³hÊh´KÏhjP  h²hubeh}”(h]”Œinhibiting-input-devices”ah ]”h"]”Œinhibiting input devices”ah$]”h&]”uh1hµhh·h²hh³hÊh´K¨ubh¶)”}”(hhh]”(h»)”}”(hŒBasic event types”h]”hŒBasic event types”…””}”(hjÜ  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hºhjÙ  h²hh³hÊh´KÖubhÝ)”}”(hŒqThe most simple event type is EV_KEY, which is used for keys and buttons.
It's reported to the input system via::”h]”hŒrThe most simple event type is EV_KEY, which is used for keys and buttons.
Itâ€™s reported to the input system via:”…””}”(hjê  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÜh³hÊh´KØhjÙ  h²hubhí)”}”(hŒ<input_report_key(struct input_dev *dev, int code, int value)”h]”hŒ<input_report_key(struct input_dev *dev, int code, int value)”…””}”hjø  sbah}”(h]”h ]”h"]”h$]”h&]”hühýuh1hìh³hÊh´KÛhjÙ  h²hubhÝ)”}”(hX  See uapi/linux/input-event-codes.h for the allowable values of code (from 0 to
KEY_MAX). Value is interpreted as a truth value, i.e. any non-zero value means
key pressed, zero value means key released. The input code generates events only
in case the value is different from before.”h]”hX  See uapi/linux/input-event-codes.h for the allowable values of code (from 0 to
KEY_MAX). Value is interpreted as a truth value, i.e. any non-zero value means
key pressed, zero value means key released. The input code generates events only
in case the value is different from before.”…””}”(hj  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÜh³hÊh´KÝhjÙ  h²hubhÝ)”}”(hXÕ  In addition to EV_KEY, there are two more basic event types: EV_REL and
EV_ABS. They are used for relative and absolute values supplied by the
device. A relative value may be for example a mouse movement in the X axis.
The mouse reports it as a relative difference from the last position,
because it doesn't have any absolute coordinate system to work in. Absolute
events are namely for joysticks and digitizers - devices that do work in an
absolute coordinate systems.”h]”hX×  In addition to EV_KEY, there are two more basic event types: EV_REL and
EV_ABS. They are used for relative and absolute values supplied by the
device. A relative value may be for example a mouse movement in the X axis.
The mouse reports it as a relative difference from the last position,
because it doesnâ€™t have any absolute coordinate system to work in. Absolute
events are namely for joysticks and digitizers - devices that do work in an
absolute coordinate systems.”…””}”(hj  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÜh³hÊh´KâhjÙ  h²hubhÝ)”}”(hŒuHaving the device report EV_REL buttons is as simple as with EV_KEY; simply
set the corresponding bits and call the::”h]”hŒtHaving the device report EV_REL buttons is as simple as with EV_KEY; simply
set the corresponding bits and call the:”…””}”(hj"  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÜh³hÊh´KêhjÙ  h²hubhí)”}”(hŒ<input_report_rel(struct input_dev *dev, int code, int value)”h]”hŒ<input_report_rel(struct input_dev *dev, int code, int value)”…””}”hj0  sbah}”(h]”h ]”h"]”h$]”h&]”hühýuh1hìh³hÊh´KíhjÙ  h²hubhÝ)”}”(hŒ8function. Events are generated only for non-zero values.”h]”hŒ8function. Events are generated only for non-zero values.”…””}”(hj>  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÜh³hÊh´KïhjÙ  h²hubhÝ)”}”(hŒæHowever EV_ABS requires a little special care. Before calling
input_register_device, you have to fill additional fields in the input_dev
struct for each absolute axis your device has. If our button device had also
the ABS_X axis::”h]”hŒåHowever EV_ABS requires a little special care. Before calling
input_register_device, you have to fill additional fields in the input_dev
struct for each absolute axis your device has. If our button device had also
the ABS_X axis:”…””}”(hjL  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÜh³hÊh´KñhjÙ  h²hubhí)”}”(hŒ{button_dev.absmin[ABS_X] = 0;
button_dev.absmax[ABS_X] = 255;
button_dev.absfuzz[ABS_X] = 4;
button_dev.absflat[ABS_X] = 8;”h]”hŒ{button_dev.absmin[ABS_X] = 0;
button_dev.absmax[ABS_X] = 255;
button_dev.absfuzz[ABS_X] = 4;
button_dev.absflat[ABS_X] = 8;”…””}”hjZ  sbah}”(h]”h ]”h"]”h$]”h&]”hühýuh1hìh³hÊh´KöhjÙ  h²hubhÝ)”}”(hŒOr, you can just say::”h]”hŒOr, you can just say:”…””}”(hjh  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÜh³hÊh´KûhjÙ  h²hubhí)”}”(hŒ6input_set_abs_params(button_dev, ABS_X, 0, 255, 4, 8);”h]”hŒ6input_set_abs_params(button_dev, ABS_X, 0, 255, 4, 8);”…””}”hjv  sbah}”(h]”h ]”h"]”h$]”h&]”hühýuh1hìh³hÊh´KýhjÙ  h²hubhÝ)”}”(hX?  This setting would be appropriate for a joystick X axis, with the minimum of
0, maximum of 255 (which the joystick *must* be able to reach, no problem if
it sometimes reports more, but it must be able to always reach the min and
max values), with noise in the data up to +- 4, and with a center flat
position of size 8.”h]”(hŒsThis setting would be appropriate for a joystick X axis, with the minimum of
0, maximum of 255 (which the joystick ”…””}”(hj„  h²hh³Nh´NubhŒemphasis”“”)”}”(hŒ*must*”h]”hŒmust”…””}”(hjŽ  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1jŒ  hj„  ubhŒÆ be able to reach, no problem if
it sometimes reports more, but it must be able to always reach the min and
max values), with noise in the data up to +- 4, and with a center flat
position of size 8.”…””}”(hj„  h²hh³Nh´Nubeh}”(h]”h ]”h"]”h$]”h&]”uh1hÜh³hÊh´KÿhjÙ  h²hubhÝ)”}”(hŒ¨If you don't need absfuzz and absflat, you can set them to zero, which mean
that the thing is precise and always returns to exactly the center position
(if it has any).”h]”hŒªIf you donâ€™t need absfuzz and absflat, you can set them to zero, which mean
that the thing is precise and always returns to exactly the center position
(if it has any).”…””}”(hj¦  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÜh³hÊh´MhjÙ  h²hubeh}”(h]”Œbasic-event-types”ah ]”h"]”Œbasic event types”ah$]”h&]”uh1hµhh·h²hh³hÊh´KÖubh¶)”}”(hhh]”(h»)”}”(hŒ'BITS_TO_LONGS(), BIT_WORD(), BIT_MASK()”h]”hŒ'BITS_TO_LONGS(), BIT_WORD(), BIT_MASK()”…””}”(hj¿  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hºhj¼  h²hh³hÊh´M
ubhÝ)”}”(hŒBThese three macros from bitops.h help some bitfield computations::”h]”hŒAThese three macros from bitops.h help some bitfield computations:”…””}”(hjÍ  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÜh³hÊh´Mhj¼  h²hubhí)”}”(hŒÞBITS_TO_LONGS(x) - returns the length of a bitfield array in longs for
                   x bits
BIT_WORD(x)      - returns the index in the array in longs for bit x
BIT_MASK(x)      - returns the index in a long for bit x”h]”hŒÞBITS_TO_LONGS(x) - returns the length of a bitfield array in longs for
                   x bits
BIT_WORD(x)      - returns the index in the array in longs for bit x
BIT_MASK(x)      - returns the index in a long for bit x”…””}”hjÛ  sbah}”(h]”h ]”h"]”h$]”h&]”hühýuh1hìh³hÊh´Mhj¼  h²hubeh}”(h]”Œbits-to-longs-bit-word-bit-mask”ah ]”h"]”Œ'bits_to_longs(), bit_word(), bit_mask()”ah$]”h&]”uh1hµhh·h²hh³hÊh´M
ubh¶)”}”(hhh]”(h»)”}”(hŒThe id* and name fields”h]”hŒThe id* and name fields”…””}”(hjô  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hºhjñ  h²hh³hÊh´MubhÝ)”}”(hŒµThe dev->name should be set before registering the input device by the input
device driver. It's a string like 'Generic button device' containing a
user friendly name of the device.”h]”hŒ»The dev->name should be set before registering the input device by the input
device driver. Itâ€™s a string like â€˜Generic button deviceâ€™ containing a
user friendly name of the device.”…””}”(hj  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÜh³hÊh´Mhjñ  h²hubhÝ)”}”(hX#  The id* fields contain the bus ID (PCI, USB, ...), vendor ID and device ID
of the device. The bus IDs are defined in input.h. The vendor and device IDs
are defined in pci_ids.h, usb_ids.h and similar include files. These fields
should be set by the input device driver before registering it.”h]”hX#  The id* fields contain the bus ID (PCI, USB, ...), vendor ID and device ID
of the device. The bus IDs are defined in input.h. The vendor and device IDs
are defined in pci_ids.h, usb_ids.h and similar include files. These fields
should be set by the input device driver before registering it.”…””}”(hj  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÜh³hÊh´Mhjñ  h²hubhÝ)”}”(hŒRThe idtype field can be used for specific information for the input device
driver.”h]”hŒRThe idtype field can be used for specific information for the input device
driver.”…””}”(hj  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÜh³hÊh´Mhjñ  h²hubhÝ)”}”(hŒIThe id and name fields can be passed to userland via the evdev interface.”h]”hŒIThe id and name fields can be passed to userland via the evdev interface.”…””}”(hj,  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÜh³hÊh´M"hjñ  h²hubeh}”(h]”Œthe-id-and-name-fields”ah ]”h"]”Œthe id* and name fields”ah$]”h&]”uh1hµhh·h²hh³hÊh´Mubh¶)”}”(hhh]”(h»)”}”(hŒ+The keycode, keycodemax, keycodesize fields”h]”hŒ+The keycode, keycodemax, keycodesize fields”…””}”(hjE  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hºhjB  h²hh³hÊh´M%ubhÝ)”}”(hX  These three fields should be used by input devices that have dense keymaps.
The keycode is an array used to map from scancodes to input system keycodes.
The keycode max should contain the size of the array and keycodesize the
size of each entry in it (in bytes).”h]”hX  These three fields should be used by input devices that have dense keymaps.
The keycode is an array used to map from scancodes to input system keycodes.
The keycode max should contain the size of the array and keycodesize the
size of each entry in it (in bytes).”…””}”(hjS  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÜh³hÊh´M'hjB  h²hubhÝ)”}”(hX+  Userspace can query and alter current scancode to keycode mappings using
EVIOCGKEYCODE and EVIOCSKEYCODE ioctls on corresponding evdev interface.
When a device has all 3 aforementioned fields filled in, the driver may
rely on kernel's default implementation of setting and querying keycode
mappings.”h]”hX-  Userspace can query and alter current scancode to keycode mappings using
EVIOCGKEYCODE and EVIOCSKEYCODE ioctls on corresponding evdev interface.
When a device has all 3 aforementioned fields filled in, the driver may
rely on kernelâ€™s default implementation of setting and querying keycode
mappings.”…””}”(hja  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÜh³hÊh´M,hjB  h²hubeh}”(h]”Œ)the-keycode-keycodemax-keycodesize-fields”ah ]”h"]”Œ+the keycode, keycodemax, keycodesize fields”ah$]”h&]”uh1hµhh·h²hh³hÊh´M%ubh¶)”}”(hhh]”(h»)”}”(hŒ'dev->getkeycode() and dev->setkeycode()”h]”hŒ'dev->getkeycode() and dev->setkeycode()”…””}”(hjz  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hºhjw  h²hh³hÊh´M3ubhÝ)”}”(hŒ´getkeycode() and setkeycode() callbacks allow drivers to override default
keycode/keycodesize/keycodemax mapping mechanism provided by input core
and implement sparse keycode maps.”h]”hŒ´getkeycode() and setkeycode() callbacks allow drivers to override default
keycode/keycodesize/keycodemax mapping mechanism provided by input core
and implement sparse keycode maps.”…””}”(hjˆ  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÜh³hÊh´M5hjw  h²hubeh}”(h]”Œ!dev-getkeycode-and-dev-setkeycode”ah ]”h"]”Œ'dev->getkeycode() and dev->setkeycode()”ah$]”h&]”uh1hµhh·h²hh³hÊh´M3ubh¶)”}”(hhh]”(h»)”}”(hŒKey autorepeat”h]”hŒKey autorepeat”…””}”(hj¡  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hºhjž  h²hh³hÊh´M:ubhÝ)”}”(hXC  ... is simple. It is handled by the input.c module. Hardware autorepeat is
not used, because it's not present in many devices and even where it is
present, it is broken sometimes (at keyboards: Toshiba notebooks). To enable
autorepeat for your device, just set EV_REP in dev->evbit. All will be
handled by the input system.”h]”hXE  ... is simple. It is handled by the input.c module. Hardware autorepeat is
not used, because itâ€™s not present in many devices and even where it is
present, it is broken sometimes (at keyboards: Toshiba notebooks). To enable
autorepeat for your device, just set EV_REP in dev->evbit. All will be
handled by the input system.”…””}”(hj¯  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÜh³hÊh´M<hjž  h²hubeh}”(h]”Œkey-autorepeat”ah ]”h"]”Œkey autorepeat”ah$]”h&]”uh1hµhh·h²hh³hÊh´M:ubh¶)”}”(hhh]”(h»)”}”(hŒ)Other event types, handling output events”h]”hŒ)Other event types, handling output events”…””}”(hjÈ  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hºhjÅ  h²hh³hÊh´MCubhÝ)”}”(hŒ$The other event types up to now are:”h]”hŒ$The other event types up to now are:”…””}”(hjÖ  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÜh³hÊh´MEhjÅ  h²hubhŒbullet_list”“”)”}”(hhh]”(hŒ	list_item”“”)”}”(hŒ$EV_LED - used for the keyboard LEDs.”h]”hÝ)”}”(hjí  h]”hŒ$EV_LED - used for the keyboard LEDs.”…””}”(hjï  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÜh³hÊh´MGhjë  ubah}”(h]”h ]”h"]”h$]”h&]”uh1jé  hjæ  h²hh³hÊh´Nubjê  )”}”(hŒ"EV_SND - used for keyboard beeps.
”h]”hÝ)”}”(hŒ!EV_SND - used for keyboard beeps.”h]”hŒ!EV_SND - used for keyboard beeps.”…””}”(hj  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÜh³hÊh´MHhj  ubah}”(h]”h ]”h"]”h$]”h&]”uh1jé  hjæ  h²hh³hÊh´Nubeh}”(h]”h ]”h"]”h$]”h&]”Œbullet”Œ-”uh1jä  h³hÊh´MGhjÅ  h²hubhÝ)”}”(hX  They are very similar to for example key events, but they go in the other
direction - from the system to the input device driver. If your input device
driver can handle these events, it has to set the respective bits in evbit,
*and* also the callback routine::”h]”(hŒãThey are very similar to for example key events, but they go in the other
direction - from the system to the input device driver. If your input device
driver can handle these events, it has to set the respective bits in evbit,
”…””}”(hj"  h²hh³Nh´Nubj  )”}”(hŒ*and*”h]”hŒand”…””}”(hj*  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1jŒ  hj"  ubhŒ also the callback routine:”…””}”(hj"  h²hh³Nh´Nubeh}”(h]”h ]”h"]”h$]”h&]”uh1hÜh³hÊh´MJhjÅ  h²hubhí)”}”(hX#  button_dev->event = button_event;

int button_event(struct input_dev *dev, unsigned int type,
                 unsigned int code, int value)
{
        if (type == EV_SND && code == SND_BELL) {
                outb(value, BUTTON_BELL);
                return 0;
        }
        return -1;
}”h]”hX#  button_dev->event = button_event;

int button_event(struct input_dev *dev, unsigned int type,
                 unsigned int code, int value)
{
        if (type == EV_SND && code == SND_BELL) {
                outb(value, BUTTON_BELL);
                return 0;
        }
        return -1;
}”…””}”hjB  sbah}”(h]”h ]”h"]”h$]”h&]”hühýuh1hìh³hÊh´MOhjÅ  h²hubhÝ)”}”(hŒšThis callback routine can be called from an interrupt or a BH (although that
isn't a rule), and thus must not sleep, and must not take too long to finish.”h]”hŒœThis callback routine can be called from an interrupt or a BH (although that
isnâ€™t a rule), and thus must not sleep, and must not take too long to finish.”…””}”(hjP  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÜh³hÊh´M[hjÅ  h²hubeh}”(h]”Œ(other-event-types-handling-output-events”ah ]”h"]”Œ)other event types, handling output events”ah$]”h&]”uh1hµhh·h²hh³hÊh´MCubh¶)”}”(hhh]”(h»)”}”(hŒPolled input devices”h]”hŒPolled input devices”…””}”(hji  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hºhjf  h²hh³hÊh´M_ubhÝ)”}”(hŒZInput polling is set up by passing an input device struct and a callback to
the function::”h]”hŒYInput polling is set up by passing an input device struct and a callback to
the function:”…””}”(hjw  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÜh³hÊh´Mahjf  h²hubhí)”}”(hŒZint input_setup_polling(struct input_dev *dev,
    void (*poll_fn)(struct input_dev *dev))”h]”hŒZint input_setup_polling(struct input_dev *dev,
    void (*poll_fn)(struct input_dev *dev))”…””}”hj…  sbah}”(h]”h ]”h"]”h$]”h&]”hühýuh1hìh³hÊh´Mdhjf  h²hubhÝ)”}”(hŒxWithin the callback, devices should use the regular input_report_* functions
and input_sync as is used by other devices.”h]”hŒxWithin the callback, devices should use the regular input_report_* functions
and input_sync as is used by other devices.”…””}”(hj“  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÜh³hÊh´Mghjf  h²hubhÝ)”}”(hŒThere is also the function::”h]”hŒThere is also the function:”…””}”(hj¡  h²hh³Nh´Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÜh³hÊh´Mjhjf  h²hubhí)”}”(hŒJvoid input_set_poll_interval(struct input_dev *dev, unsigned int interval)”h]”hŒJvoid input_set_poll_interval(struct input_dev *dev, unsigned int interval)”…””}”hj¯  sbah}”(h]”h ]”h"]”h$]”h&]”hühýuh1hìh³hÊh´Mlhjf  h²hubhÝ)”}”(hŒ\which is used to configure the interval, in milliseconds, that the device will
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