MLK Input Devices Driver

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Then it allocates a new input device structure with inputallocatedevice 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 EVKEY type events, and from those only BTN0 event code. Download Soundcraft Multichannel USB Audio Driver V3.20 WINDOWS 10 OPERATING SYSTEM NOTIFICATION Windows 10 enforces driver signatures by default. This can be disabled to install drivers that are not digitally signed. When you plug the device into your USB, Windows will look for the associated driver, if it cannot find this driver then you will be prompted to insert the driver disc that came with your device. Common USB Device errors are ‘ usb port not working ‘, ‘device descriptor request failed error’ or ‘bugcodeusbdriver’ issues. With my device driver I want to set just the GPIO pin 10 as output and read GPIO pin 14 as input. So I have to write a set up command into the “function set 1” register with offset 4. To get a clear situation I first set all GPIO pins 10 to 19 as inputs by the command.

1.1. The simplest example¶

The function driver creates a function device object (FDO) and attaches it to the device stack. In this example, the function driver for the USB joystick is actually a pair of drivers: the HID class driver and the HID miniclass driver. The two drivers work together to serve as the function driver.

Here comes a very simple example of an input device driver. The device hasjust one button and the button is accessible at i/o port BUTTON_PORT. Whenpressed or released a BUTTON_IRQ happens. The driver could look like:

1.2. What the example does¶

First it has to include the <linux/input.h> file, which interfaces to theinput subsystem. This provides all the definitions needed.

In the _init function, which is called either upon module load or whenbooting the kernel, it grabs the required resources (it should also checkfor the presence of the device).

Then it allocates a new input device structure with input_allocate_device()and sets up input bitfields. This way the device driver tells the otherparts of the input systems what it is - what events can be generated oraccepted by this input device. Our example device can only generate EV_KEYtype events, and from those only BTN_0 event code. Thus we only set thesetwo bits. We could have used:

as well, but with more than single bits the first approach tends to beshorter.

Then the example driver registers the input device structure by calling:

This adds the button_dev structure to linked lists of the input driver andcalls device handler modules _connect functions to tell them a new inputdevice has appeared. input_register_device() may sleep and therefore mustnot be called from an interrupt or with a spinlock held.

While in use, the only used function of the driver is:

which upon every interrupt from the button checks its state and reports itvia the:

call to the input system. There is no need to check whether the interruptroutine isn’t reporting two same value events (press, press for example) tothe input system, because the input_report_* functions check thatthemselves.

Then there is the:

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 importantfor for example mouse movement, where you don’t want the X and Y valuesto be interpreted separately, because that’d result in a different movement.

1.3. dev->open() and dev->close()¶

In case the driver has to repeatedly poll the device, because it doesn’thave an interrupt coming from it and the polling is too expensive to be doneall the time, or if the device uses a valuable resource (eg. interrupt), itcan use the open and close callback to know when it can stop polling orrelease the interrupt and when it must resume polling or grab the interruptagain. To do that, we would add this to our example driver:

Note that input core keeps track of number of users for the device andmakes sure that dev->open() is called only when the first user connectsto the device and that dev->close() is called when the very last userdisconnects. Calls to both callbacks are serialized.

The open() callback should return a 0 in case of success or any nonzero valuein case of failure. The close() callback (which is void) must always succeed.

1.4. Inhibiting input devices¶

Inhibiting a device means ignoring input events from it. As such it is aboutmaintaining relationships with input handlers - either already existingrelationships, or relationships to be established while the device is ininhibited state.

If a device is inhibited, no input handler will receive events from it.

The fact that nobody wants events from the device is exploited further, bycalling device’s close() (if there are users) and open() (if there are users) oninhibit and uninhibit operations, respectively. Indeed, the meaning of close()is to stop providing events to the input core and that of open() is to startproviding events to the input core.

Calling the device’s close() method on inhibit (if there are users) allows thedriver to save power. Either by directly powering down the device or byreleasing the runtime-pm reference it got in open() when the driver is usingruntime-pm.

Inhibiting and uninhibiting are orthogonal to opening and closing the device byinput handlers. Userspace might want to inhibit a device in anticipation beforeany handler is positively matched against it.

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 whenthe system is operating. How drivers should program their interaction betweeninhibiting, sleeping and being a wakeup source is driver-specific.

Taking the analogy with the network devices - bringing a network interface downdoesn’t mean that it should be impossible be wake the system up on LAN throughthis interface. So, there may be input drivers which should be considered wakeupsources even when inhibited. Actually, in many I2C input devices their interruptis declared a wakeup interrupt and its handling happens in driver’s core, whichis not aware of input-specific inhibit (nor should it be). Composite devicescontaining 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 awakeup source.

If a device is to be considered a wakeup source while inhibited, special caremust be taken when programming its suspend(), as it might need to call device’sopen(). Depending on what close() means for the device in question, notopening() it before going to sleep might make it impossible to provide anywakeup events. The device is going to sleep anyway.

1.5. Basic event types¶

The most simple event type is EV_KEY, which is used for keys and buttons.It’s reported to the input system via:

See uapi/linux/input-event-codes.h for the allowable values of code (from 0 toKEY_MAX). Value is interpreted as a truth value, ie any nonzero value means keypressed, zero value means key released. The input code generates events onlyin case the value is different from before.

In addition to EV_KEY, there are two more basic event types: EV_REL andEV_ABS. They are used for relative and absolute values supplied by thedevice. 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. Absoluteevents are namely for joysticks and digitizers - devices that do work in anabsolute coordinate systems.

Having the device report EV_REL buttons is as simple as with EV_KEY, simplyset the corresponding bits and call the:

function. Events are generated only for nonzero value.

However EV_ABS requires a little special care. Before callinginput_register_device, you have to fill additional fields in the input_devstruct for each absolute axis your device has. If our button device had alsothe ABS_X axis:

Or, you can just say:

This setting would be appropriate for a joystick X axis, with the minimum of0, maximum of 255 (which the joystick must be able to reach, no problem ifit sometimes reports more, but it must be able to always reach the min andmax values), with noise in the data up to +- 4, and with a center flatposition of size 8.

If you don’t need absfuzz and absflat, you can set them to zero, which meanthat the thing is precise and always returns to exactly the center position(if it has any).

1.6. BITS_TO_LONGS(), BIT_WORD(), BIT_MASK()¶

These three macros from bitops.h help some bitfield computations:

1.7. The id* and name fields¶

The dev->name should be set before registering the input device by the inputdevice driver. It’s a string like ‘Generic button device’ containing auser friendly name of the device.

The id* fields contain the bus ID (PCI, USB, …), vendor ID and device IDof the device. The bus IDs are defined in input.h. The vendor and device idsare defined in pci_ids.h, usb_ids.h and similar include files. These fieldsshould be set by the input device driver before registering it.

The idtype field can be used for specific information for the input devicedriver.

The id and name fields can be passed to userland via the evdev interface.

1.8. The keycode, keycodemax, keycodesize fields¶

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 thesize of each entry in it (in bytes).

Userspace can query and alter current scancode to keycode mappings usingEVIOCGKEYCODE and EVIOCSKEYCODE ioctls on corresponding evdev interface.When a device has all 3 aforementioned fields filled in, the driver mayrely on kernel’s default implementation of setting and querying keycodemappings.

1.9. dev->getkeycode() and dev->setkeycode()¶

getkeycode() and setkeycode() callbacks allow drivers to override defaultkeycode/keycodesize/keycodemax mapping mechanism provided by input coreand implement sparse keycode maps.

1.10. Key autorepeat¶

… is simple. It is handled by the input.c module. Hardware autorepeat isnot used, because it’s not present in many devices and even where it ispresent, it is broken sometimes (at keyboards: Toshiba notebooks). To enableautorepeat for your device, just set EV_REP in dev->evbit. All will behandled by the input system.

1.11. Other event types, handling output events¶

The other event types up to now are:

  • EV_LED - used for the keyboard LEDs.
  • EV_SND - used for keyboard beeps.

They are very similar to for example key events, but they go in the otherdirection - from the system to the input device driver. If your input devicedriver can handle these events, it has to set the respective bits in evbit,and also the callback routine:

This callback routine can be called from an interrupt or a BH (although thatisn’t a rule), and thus must not sleep, and must not take too long to finish.

You can use Android Debug Bridge (ADB) to connect your Fire tablet to your computer for testing and debugging. You connect your computer to your Fire tablet through a micro-USB cable.

Android Debug Bridge (ADB) is a command-line utility for running and managing Android apps on your device or emulator. For more information and instructions on using ADB, see Android Debug Bridge.

If you're looking for instructions on connecting to a Fire TV instead, see Connect to Fire TV Through ADB.

  • Check for Device Connections Using ADB (Optional)
  • Troubleshooting

Step 1: Enable Developer Options

  1. Go to Settings > Device Options and look for a Developer Options menu. If it's not there, do the following:

    a. Go to Settings > Device Options > About Fire Tablet.b. Tap your Serial Number seven times.c. Return to Device Options. A new menu appears called 'Developer Options.'

  2. Tap Developer options. (2013 models might call this option 'Security.')
  3. Set Developer options and USB debugging to ON.
  • If you have a Kindle Fire 1st Generation, ADB is enabled by default.

Step 2: Install the Kindle Fire Driver (Windows Only)

  1. If you're using Windows, download this Kindle Fire driver: kindle_fire_usb_driver.zip.
  2. After downloading the file, extract the contents into a new folder and double-click the Fire_Devices ABD drivers file.
  3. Proceed through the installation wizard screens to install the driver.

Step 3: Install Android Studio

ADB is available on your computer when you install Android Studio. If you don't already have Android Studio, download and install Android Studio. If you're not using Android Studio, you need to download and install Android SDK platform tools.

Step 4: Connect Your Fire Device to Your Computer with a USB Cable

  1. Using a USB cable, connect your Fire tablet to a USB port on your computer.

    Note that Fire tablets can treat the USB with different transfer options. After connecting the USB cable, swipe down from the top of your tablet to see the USB option used. You might see various notifications, including the USB connection type that was used when you connected the cable. The relevant notification is highlighted in the screenshot below.

    If you don't see 'Connected as Media Device', press Tap for other USB options. Then select Media device (MTP). Later Fire OS versions have a different interface here. If you're using Fire OS 7, select File Transfer.

    Note: If your USB is connected as a Camera (PTP), Android Studio won't recognize the tablet as a device in Android Studio.

    If you don't see the USB connection type in the above notifications, go to Settings > Device Options > Developer Options > USB computer connection. Set this to Media device (MTP). For Fire OS 7, select File Transfer.

  2. When the Allow USB debugging? dialog appears on your tablet, tap OK.

  3. Open Android Studio and look for the device to appear in devices drop-down menu:

    The device's name will use the android.os.Build.MODEL property for the device. KFSUWI refers to Fire HD 10 (2017) tablet. You can see a list of build model names in the Identifying Fire Tablet Devices.

    If you have not selected the 'Allow USB Debugging' dialog on your tablet, the name 'Unknown device' will appear in the devices drop-down menu in Android Studio until you allow debugging.

  4. With the tablet connected, you can now run your app on your tablet by clicking the Run App button in Android Studio.

If you run into issues, see the Troubleshooting section below.

Check for Device Connections Using ADB (Optional)

Instead of looking in the devices menu in Android Studio, you can also use some ADB terminal commands to confirm that your device is connected. ADB is useful for performing many other operations as well, such as entering sandbox mode or installing other assets. Follow these two sections:

If you skip adding ADB to your PATH, you can also Check for Connected Devices If ADB Isn't In Your PATH.

Add ADB to Your PATH

MLK Input Devices Driver

First, add ADB to your PATH so you can more easily run ADB commands. (Your PATH is an environment variable used to specify the location of the program's executable. If you don't add ADB to your PATH, running ADB commands will require you to browse to the <Android SDK>/platform-tools directory to run adb.)

MLK Input Devices Driver

Tip: You can check whether ADB is already added to your PATH by typing adb version from a terminal or command prompt. If you get back version information, then ADB is in your PATH. If the response says adb is an unrecognized command, ADB is not in your PATH.
Mlk input devices driver list

To add ADB to your PATH on Mac:

  1. Get the path to your Android SDK platform-tools directory:

    1. Open Android Studio and click the SDK Manager button .The location to your Android SDK appears near the top next to Android SDK Location. For example: /Users/<your username>/Library/Android/sdk

      If this is your first time opening Android Studio, there isn't an SDK Manager button. Instead, at the Welcome to Android Studio prompt, click Configure > SDK Manager and provide the location to the Android SDK.

    2. Copy the path to the SDK and paste it somewhere convenient, such as a text editor.
    3. Add /platform-tools to the end of the path you copied in the previous step. ('platform-tools' is the directory containing the ADB executable.)
    4. Copy the full path to your clipboard.
  2. Use the following command to add ADB to your .bash_profile. Replace <your username> with your actual username. Also, make sure the path points to your Android SDK.

    Your .bash_profile file is usually in your user directory, which you can find by typing cd ~ (change to your user directory). Then type ls -a (list all) to show all files, including hidden ones.

    If the file isn't there, simply create one. You can then type open .bash_profile to see the paths listed.

    After you add this PATH to your bash profile, you should see the following in your .bash_profile file:

    (Only instead of johndoe, you will see your own username.)

  3. Fully restart any terminal sessions, and then type adb. If you successfully added ADB to your path, you will see ADB help info rather than 'command not found.'

To add ADB to your PATH on Windows:

  1. Get the path to your Android SDK platform-tools directory:

    1. Open Android Studio and click the SDK Manager button .

      The location to your Android SDK appears near the top next to Android SDK Location. For example: C:Users<your user name>AppDataLocalAndroidSdk

      If this is your first time opening Android Studio, there isn't an SDK Manager button. Instead, at the Welcome to Android Studio prompt, click Configure > SDK Manager and provide the location to the Android SDK.

    2. Copy the path to the SDK and paste it somewhere convenient, such as a text editor.
    3. Add /platform-tools to the end of the path you copied in the previous step. ('platform-tools' is the directory containing the ADB executable.)
    4. Copy the full path to your clipboard.
  2. Click your computer's search button (next to Start) and type view advanced system settings.
  3. Click View advanced system settings.
  4. When the System Settings dialog opens, click the Environment Variables button.
  5. Under System Variables (the lower pane), select Path and click Edit.
  6. Do one of the following:

    • On Windows 7 or 8, move your cursor to the farthest position on the right, type ; and then press Ctrl+V to insert the path to your SDK that you copied earlier. It may look like this: ;C:Users<your user name>AppDataLocalAndroidSdkplatform-tools. Click OK on each of the three open dialog boxes to close them.
    • On Windows 10, click the New button and add this location.
  7. Restart any terminal sessions, and then type adb. If you successfully added ADB to your path, you will see ADB help info rather than 'command not found.'

Check for Connected Devices

  1. Assuming ADB is added to your PATH, run the following commands:

  2. Confirm that the serial number for your Fire tablet appears in the list of devices. For example:

    On your tablet, your device's serial number is located under Settings > Device Options.

Check for Connected Devices If ADB Isn't In Your PATH

If your terminal doesn't recognize adb as a command (that is, you didn't add ADB to your PATH), you might have to run the commands from the SDK directory that contains ADB.

  1. In Android Studio go to Tools > SDK Manager.
  2. In the SDK Manager dialog box, copy the Android SDK Location.
  3. Browse to this location in your terminal or command prompt. For example:

    Mac

    Windows

    Then go into the platform-tools directory:

    The platform-tools directory contains adb.

  4. Now run the ADB commands as follows:

    Mac:

    Windows:

    The response should list your device's serial number. For example:

    If your Fire tablet is still not detected, you may need to reboot your computer or log out and back in for the changes to take effect.

Troubleshooting

Mlk Input Devices Drivers

Tablet doesn't appear in list of devices in Android Studio

Mlk Input Devices Driver Download

  1. If you don't see your tablet device in the list of devices in Android Studio, click the devices drop-down menu and select Troubleshoot device connections:

  2. Click Rescan devices.

    If rescanning devices doesn't detect your Fire tablet as a device, your micro-USB cable might be bad, you might have the wrong USB connection type (e.g, camera instead of media device), or you might not have enabled USB debugging. You can also try restarting your computer and the tablet.

Uninstall the non-ADB Driver (Windows)

If you previously connected a Fire tablet without first enabling ADB on the Fire tablet, you might need to remove the existing USB device driver and force re-installation of the driver. To remove the non-ADB driver:

  1. Using a micro-USB cable, connect your Fire tablet to a USB port on your computer.
  2. On your computer (Windows 10), click the search button (next to the Start menu) and type Device Manager in the search. Then select it in the results. (Other Windows versions have different options for accessing the Control Panel.)
  3. In the Device Manager window, expand Portable Devices.
  4. Right-click the Fire device and then click Properties.
  5. In the Properties window, on the Driver tab, click Uninstall, and then Confirm.
  6. Unplug your Fire tablet from your computer.

Confirm the Fire Driver Is Installed Correctly

You can confirm that the Fire driver is installed correctly by doing the following:

Mlk Input Devices Driver List

  1. On your computer, click the search button search button (next to the Start menu) and type Device Manager.
  2. In Device Manager, under Fire Devices, verify that that a device appears called Android Composite ADB Interface.

    If your Device Manager shows an Other Devices section with a second Fire device with a yellow alert sign, your computer is listing Amazon's unrecognized ADB module as a separate device. To fix this issue:

    1. Under Other Devices, right-click the Fire device and select Properties.
    2. On the Driver tab of the Properties window, select Update Driver…
    3. Choose to browse for the driver software, then navigate to Let me pick from a list of device drivers on my computer > Show All Devices > Have Disk.
    4. Navigate to the folder where you installed the Amazon driver (typically C:Program Files (x86)Amazon.comFire_DevicesDrivers) and select it.
    5. Ignore the warning regarding installing drivers and proceed.

      You should now correctly see your Fire tablet with the ADB driver installed.

Mlk Input Devices Driver Update

Last updated: Oct 29, 2020