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| <li class="toctree-l2"><a class="reference internal" href="../binfmt.html">Binary Loader</a></li> |
| <li class="toctree-l2 current"><a class="current reference internal" href="#">Device Drivers</a><ul> |
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| <li class="toctree-l3"><a class="reference internal" href="block/index.html">Block Device Drivers</a></li> |
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| <li class="toctree-l3"><a class="reference internal" href="#subdirectories-of-nuttx-drivers">Subdirectories of <code class="docutils literal notranslate"><span class="pre">nuttx/drivers</span></code></a></li> |
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| |
| <section id="device-drivers"> |
| <h1>Device Drivers<a class="headerlink" href="#device-drivers" title="Permalink to this heading"></a></h1> |
| <p>NuttX supports a variety of device drivers, which can be broadly |
| divided in three classes:</p> |
| <div class="toctree-wrapper compound"> |
| <ul> |
| <li class="toctree-l1"><a class="reference internal" href="character/index.html">Character Device Drivers</a></li> |
| <li class="toctree-l1"><a class="reference internal" href="block/index.html">Block Device Drivers</a></li> |
| <li class="toctree-l1"><a class="reference internal" href="special/index.html">Specialized Device Drivers</a></li> |
| <li class="toctree-l1"><a class="reference internal" href="thermal/index.html">Thermal Framework</a></li> |
| </ul> |
| </div> |
| <div class="admonition note"> |
| <p class="admonition-title">Note</p> |
| <p>Device driver support depends on the <em>in-memory</em>, <em>pseudo</em> |
| file system that is enabled by default.</p> |
| </div> |
| <section id="lower-half-and-upper-half"> |
| <h2>Lower-half and upper-half<a class="headerlink" href="#lower-half-and-upper-half" title="Permalink to this heading"></a></h2> |
| <p>Drivers in NuttX generally work in two distinct layers:</p> |
| <blockquote> |
| <div><ul class="simple"> |
| <li><p>An <em>upper half</em> which registers itself to NuttX using |
| a call such as <code class="xref c c-func docutils literal notranslate"><span class="pre">register_driver()</span></code> or |
| <code class="xref c c-func docutils literal notranslate"><span class="pre">register_blockdriver()</span></code> and implements the corresponding |
| high-level interface (<cite>read</cite>, <cite>write</cite>, <cite>close</cite>, etc.). |
| implements the interface. This <em>upper half</em> calls into |
| the <em>lower half</em> via callbacks.</p></li> |
| <li><p>A “lower half” which is typically hardware-specific. This is |
| usually implemented at the architecture or board level.</p></li> |
| </ul> |
| </div></blockquote> |
| </section> |
| <section id="subdirectories-of-nuttx-drivers"> |
| <h2>Subdirectories of <code class="docutils literal notranslate"><span class="pre">nuttx/drivers</span></code><a class="headerlink" href="#subdirectories-of-nuttx-drivers" title="Permalink to this heading"></a></h2> |
| <ul> |
| <li><p><code class="docutils literal notranslate"><span class="pre">1wire/</span></code> <a class="reference internal" href="character/1wire.html"><span class="doc">One Wire Drivers</span></a></p> |
| <p>1wire device drivers.</p> |
| </li> |
| <li><p><code class="docutils literal notranslate"><span class="pre">analog/</span></code> <a class="reference internal" href="character/analog/index.html"><span class="doc">Analog (ADC/DAC) Drivers</span></a></p> |
| <p>This directory holds implementations of analog device drivers. |
| This includes drivers for Analog to Digital Conversion (ADC) as |
| well as drivers for Digital to Analog Conversion (DAC).</p> |
| </li> |
| <li><p><code class="docutils literal notranslate"><span class="pre">audio/</span></code> <a class="reference internal" href="special/audio.html"><span class="doc">Audio Device Drivers</span></a></p> |
| <p>Audio device drivers.</p> |
| </li> |
| <li><p><code class="docutils literal notranslate"><span class="pre">bch/</span></code> <a class="reference internal" href="character/bch.html"><span class="doc">Block Driver to Character Driver</span></a></p> |
| <p>Contains logic that may be used to convert a block driver into |
| a character driver. This is the complementary conversion as that |
| performed by loop.c.</p> |
| </li> |
| <li><p><code class="docutils literal notranslate"><span class="pre">can/</span></code> <a class="reference internal" href="character/can.html"><span class="doc">CAN Drivers</span></a></p> |
| <p>This is the CAN drivers and logic support.</p> |
| </li> |
| <li><p><code class="docutils literal notranslate"><span class="pre">clk/</span></code><a class="reference internal" href="special/clk.html"><span class="doc">Clock management (CLK)</span></a></p> |
| <p>Clock management (CLK) device drivers.</p> |
| </li> |
| <li><p><code class="docutils literal notranslate"><span class="pre">contactless/</span></code> <a class="reference internal" href="character/contactless.html"><span class="doc">Constactless Devices</span></a></p> |
| <p>Contactless devices are related to wireless devices. They are not |
| communication devices with other similar peers, but couplers/interfaces |
| to contactless cards and tags.</p> |
| </li> |
| <li><p><code class="docutils literal notranslate"><span class="pre">crypto/</span></code> <a class="reference internal" href="character/crypto/index.html"><span class="doc">Crypto Drivers</span></a></p> |
| <p>Contains crypto drivers and support logic, including the |
| <code class="docutils literal notranslate"><span class="pre">/dev/urandom</span></code> device.</p> |
| </li> |
| <li><p><code class="docutils literal notranslate"><span class="pre">devicetree/</span></code> <a class="reference internal" href="special/devicetree.html"><span class="doc">Device Tree support</span></a></p> |
| <p>Device Tree support.</p> |
| </li> |
| <li><p><code class="docutils literal notranslate"><span class="pre">dma/</span></code> <a class="reference internal" href="special/dma.html"><span class="doc">DMA Drivers</span></a></p> |
| <p>DMA drivers support.</p> |
| </li> |
| <li><p><code class="docutils literal notranslate"><span class="pre">eeprom/</span></code> <a class="reference internal" href="block/eeprom.html"><span class="doc">EEPROM</span></a></p> |
| <p>An EEPROM is a form of Memory Technology Device (see <code class="docutils literal notranslate"><span class="pre">drivers/mtd</span></code>). |
| EEPROMs are non-volatile memory like FLASH, but differ in underlying |
| memory technology and differ in usage in many respects: They may not |
| be organized into blocks (at least from the standpoint of the user) |
| and it is not necessary to erase the EEPROM memory before re-writing |
| it. In addition, EEPROMs tend to be much smaller than FLASH parts, |
| usually only a few kilobytes vs megabytes for FLASH. EEPROM tends to |
| be used to retain a small amount of device configuration information; |
| FLASH tends to be used for program or massive data storage. For these |
| reasons, it may not be convenient to use the more complex MTD |
| interface but instead use the simple character interface provided by |
| the EEPROM drivers.</p> |
| </li> |
| <li><p><code class="docutils literal notranslate"><span class="pre">efuse/</span></code> <a class="reference internal" href="character/efuse.html"><span class="doc">EFUSE Drivers</span></a></p> |
| <p>EFUSE drivers support.</p> |
| </li> |
| <li><p><code class="docutils literal notranslate"><span class="pre">i2c/</span></code> <a class="reference internal" href="special/i2c.html"><span class="doc">I2C Device Drivers</span></a></p> |
| <p>I2C drivers and support logic.</p> |
| </li> |
| <li><p><code class="docutils literal notranslate"><span class="pre">i2s/</span></code> <a class="reference internal" href="character/i2s.html"><span class="doc">I2S Drivers</span></a></p> |
| <p>I2S drivers and support logic.</p> |
| </li> |
| <li><p><code class="docutils literal notranslate"><span class="pre">input/</span></code> <a class="reference internal" href="character/input/index.html"><span class="doc">Input Devices</span></a></p> |
| <p>This directory holds implementations of human input device (HID) drivers. |
| This includes such things as mouse, touchscreen, joystick, |
| keyboard and keypad drivers.</p> |
| <p>Note that USB HID devices are treated differently. These can be found under |
| <code class="docutils literal notranslate"><span class="pre">usbdev/</span></code> or <code class="docutils literal notranslate"><span class="pre">usbhost/</span></code>.</p> |
| </li> |
| <li><p><code class="docutils literal notranslate"><span class="pre">ioexpander/</span></code> <a class="reference internal" href="special/ioexpander.html"><span class="doc">IO Expander Device Drivers</span></a></p> |
| <p>IO Expander drivers.</p> |
| </li> |
| <li><p><code class="docutils literal notranslate"><span class="pre">ipcc/</span></code> <a class="reference internal" href="character/ipcc.html"><span class="doc">IPCC (Inter Processor Communication Controller) Driver</span></a></p> |
| <p>IPCC (Inter Processor Communication Controller) driver.</p> |
| </li> |
| <li><p><code class="docutils literal notranslate"><span class="pre">lcd/</span></code> <a class="reference internal" href="special/lcd.html"><span class="doc">LCD Character Drivers</span></a></p> |
| <p>Drivers for parallel and serial LCD and OLED type devices.</p> |
| </li> |
| <li><p><code class="docutils literal notranslate"><span class="pre">leds/</span></code> <a class="reference internal" href="character/leds/index.html"><span class="doc">LEDS</span></a></p> |
| <p>Various LED-related drivers including discrete as well as PWM- driven LEDs.</p> |
| </li> |
| <li><p><code class="docutils literal notranslate"><span class="pre">loop/</span></code> <a class="reference internal" href="character/loop.html"><span class="doc">Loop Device</span></a></p> |
| <p>Supports the standard loop device that can be used to export a |
| file (or character device) as a block device.</p> |
| <p>See <code class="docutils literal notranslate"><span class="pre">losetup()</span></code> and <code class="docutils literal notranslate"><span class="pre">loteardown()</span></code> in <code class="docutils literal notranslate"><span class="pre">include/nuttx/fs/fs.h</span></code>.</p> |
| </li> |
| <li><p><code class="docutils literal notranslate"><span class="pre">math/</span></code> <a class="reference internal" href="character/math.html"><span class="doc">Math Acceleration Drivers</span></a></p> |
| <p>MATH Acceleration drivers.</p> |
| </li> |
| <li><p><code class="docutils literal notranslate"><span class="pre">misc/</span></code> <a class="reference internal" href="character/nullzero.html"><span class="doc">dev_null.c and dev_zero.c</span></a> <a class="reference internal" href="special/rwbuffer.html"><span class="doc">rwbuffer.c</span></a> <a class="reference internal" href="block/ramdisk.html"><span class="doc">ramdisk.c</span></a></p> |
| <p>Various drivers that don’t fit elsewhere.</p> |
| </li> |
| <li><p><code class="docutils literal notranslate"><span class="pre">mmcsd/</span></code> <a class="reference internal" href="special/sdio.html"><span class="doc">SDIO Device Drivers</span></a> <a class="reference internal" href="special/mmcsd.html"><span class="doc">MMCSD Device Drivers</span></a></p> |
| <p>Support for MMC/SD block drivers. MMC/SD block drivers based on |
| SPI and SDIO/MCI interfaces are supported.</p> |
| </li> |
| <li><p><code class="docutils literal notranslate"><span class="pre">modem/</span></code> <a class="reference internal" href="character/modem.html"><span class="doc">Modem Device</span></a></p> |
| <p>Modem Support.</p> |
| </li> |
| <li><p><code class="docutils literal notranslate"><span class="pre">motor/</span></code> <a class="reference internal" href="character/motor/index.html"><span class="doc">Motor Drivers</span></a></p> |
| <p>Motor control drivers.</p> |
| </li> |
| <li><p><code class="docutils literal notranslate"><span class="pre">mtd/</span></code> <a class="reference internal" href="special/mtd.html"><span class="doc">Memory Technology Device Drivers</span></a></p> |
| <p>Memory Technology Device (MTD) drivers. Some simple drivers for |
| memory technologies like FLASH, EEPROM, NVRAM, etc.</p> |
| <p>(Note: This is a simple memory interface and should not be |
| confused with the “real” MTD developed at infradead.org. This |
| logic is unrelated; I just used the name MTD because I am not |
| aware of any other common way to refer to this class of devices).</p> |
| </li> |
| <li><p><code class="docutils literal notranslate"><span class="pre">net/</span></code> <a class="reference internal" href="special/net/index.html"><span class="doc">Network interface drivers</span></a></p> |
| <p>Network interface drivers.</p> |
| </li> |
| <li><p><code class="docutils literal notranslate"><span class="pre">notes/</span></code> <a class="reference internal" href="character/note.html"><span class="doc">Note Driver Interface</span></a></p> |
| <p>Note Driver Support.</p> |
| </li> |
| <li><p><code class="docutils literal notranslate"><span class="pre">pinctrl/</span></code> <a class="reference internal" href="special/pinctrl.html"><span class="doc">Pinctrl Device Drivers</span></a></p> |
| <p>Configure and manage pin.</p> |
| </li> |
| <li><p><code class="docutils literal notranslate"><span class="pre">pipes/</span></code> <a class="reference internal" href="special/pipes.html"><span class="doc">FIFO and named pipe drivers</span></a></p> |
| <p>FIFO and named pipe drivers. |
| Standard interfaces are declared in <code class="docutils literal notranslate"><span class="pre">include/unistd.h</span></code></p> |
| </li> |
| <li><p><code class="docutils literal notranslate"><span class="pre">power/</span></code> <a class="reference internal" href="special/power/index.html"><span class="doc">Power-related Drivers</span></a></p> |
| <p>Various drivers related to power management.</p> |
| </li> |
| <li><p><code class="docutils literal notranslate"><span class="pre">rc/</span></code> <a class="reference internal" href="character/rc.html"><span class="doc">Remote Control Devices</span></a></p> |
| <p>Remote Control Device Support.</p> |
| </li> |
| <li><p><code class="docutils literal notranslate"><span class="pre">regmap/</span></code> <a class="reference internal" href="special/regmap.html"><span class="doc">drivers/regmap</span></a></p> |
| <p>Regmap Subsystems Support.</p> |
| </li> |
| <li><p><code class="docutils literal notranslate"><span class="pre">reset/</span></code> <a class="reference internal" href="special/reset.html"><span class="doc">Reset Driver</span></a></p> |
| <p>Reset Driver Support.</p> |
| </li> |
| <li><p><code class="docutils literal notranslate"><span class="pre">rf/</span></code> <a class="reference internal" href="character/rf.html"><span class="doc">RF Devices</span></a></p> |
| <p>RF Device Support.</p> |
| </li> |
| <li><p><code class="docutils literal notranslate"><span class="pre">rptun/</span></code> <a class="reference internal" href="special/rptun.html"><span class="doc">Remote Proc Tunnel Drivers</span></a></p> |
| <p>Remote Proc Tunnel Driver Support.</p> |
| </li> |
| <li><p><code class="docutils literal notranslate"><span class="pre">segger/</span></code> <a class="reference internal" href="special/segger.html"><span class="doc">Segger RTT drivers</span></a></p> |
| <p>Segger RTT drivers.</p> |
| </li> |
| <li><p><code class="docutils literal notranslate"><span class="pre">sensors/</span></code> <a class="reference internal" href="special/sensors.html"><span class="doc">Sensor Drivers</span></a></p> |
| <p>Drivers for various sensors. A sensor driver differs little from |
| other types of drivers other than they are use to provide measurements |
| of things in environment like temperature, orientation, acceleration, |
| altitude, direction, position, etc.</p> |
| <p>DACs might fit this definition of a sensor driver as well since they |
| measure and convert voltage levels. DACs, however, are retained in |
| the <code class="docutils literal notranslate"><span class="pre">analog/</span></code> sub-directory.</p> |
| </li> |
| <li><p><code class="docutils literal notranslate"><span class="pre">serial/</span></code><a class="reference internal" href="character/serial.html"><span class="doc">Serial Device Drivers</span></a></p> |
| <p>Front-end character drivers for chip-specific UARTs. |
| This provide some TTY-like functionality and are commonly used (but |
| not required for) the NuttX system console.</p> |
| </li> |
| <li><p><code class="docutils literal notranslate"><span class="pre">spi/</span></code> <a class="reference internal" href="special/spi.html"><span class="doc">SPI Device Drivers</span></a></p> |
| <p>SPI drivers and support logic.</p> |
| </li> |
| <li><p><code class="docutils literal notranslate"><span class="pre">syslog/</span></code> <a class="reference internal" href="special/syslog.html"><span class="doc">SYSLOG</span></a></p> |
| <p>System logging devices.</p> |
| </li> |
| <li><p><code class="docutils literal notranslate"><span class="pre">timers/</span></code> <a class="reference internal" href="character/timers/index.html"><span class="doc">Timers Drivers</span></a></p> |
| <p>Includes support for various timer devices.</p> |
| </li> |
| <li><p><code class="docutils literal notranslate"><span class="pre">usbdev/</span></code> <a class="reference internal" href="special/usbdev.html"><span class="doc">USB Device-Side Drivers</span></a></p> |
| <p>USB device drivers.</p> |
| </li> |
| <li><p><code class="docutils literal notranslate"><span class="pre">usbhost/</span></code> <a class="reference internal" href="special/usbhost.html"><span class="doc">USB Host-Side Drivers</span></a></p> |
| <p>USB host drivers.</p> |
| </li> |
| <li><p><code class="docutils literal notranslate"><span class="pre">usbmisc/</span></code> <a class="reference internal" href="special/usbmisc.html"><span class="doc">USB Miscellaneous Drivers</span></a></p> |
| <p>USB Miscellaneous drivers.</p> |
| </li> |
| <li><p><code class="docutils literal notranslate"><span class="pre">usbmonitor/</span></code> <a class="reference internal" href="special/usbmonitor.html"><span class="doc">USB Monitor support</span></a></p> |
| <p>USB Monitor support.</p> |
| </li> |
| <li><p><code class="docutils literal notranslate"><span class="pre">usrsock/</span></code> <a class="reference internal" href="special/usrsock.html"><span class="doc">Usrsock Driver</span></a></p> |
| <p>Usrsock Driver Support.</p> |
| </li> |
| <li><p><code class="docutils literal notranslate"><span class="pre">video/</span></code> <a class="reference internal" href="special/video.html"><span class="doc">Video Device Drivers</span></a></p> |
| <p>Video-related drivers.</p> |
| </li> |
| <li><p><code class="docutils literal notranslate"><span class="pre">virtio/</span></code> <a class="reference internal" href="special/virtio.html"><span class="doc">Virtio Device Drivers</span></a></p> |
| <p>Virtio Device Support.</p> |
| </li> |
| <li><p><code class="docutils literal notranslate"><span class="pre">wireless/</span></code> <a class="reference internal" href="special/wireless.html"><span class="doc">Wireless Drivers</span></a></p> |
| <p>Drivers for various wireless devices.</p> |
| </li> |
| </ul> |
| </section> |
| <section id="skeleton-files"> |
| <h2>Skeleton Files<a class="headerlink" href="#skeleton-files" title="Permalink to this heading"></a></h2> |
| <p>Skeleton files are “empty” frameworks for NuttX drivers. They are provided to |
| give you a good starting point if you want to create a new NuttX driver. |
| The following skeleton files are available:</p> |
| <ul class="simple"> |
| <li><p><code class="docutils literal notranslate"><span class="pre">drivers/lcd/skeleton.c</span></code> Skeleton LCD driver</p></li> |
| <li><p><code class="docutils literal notranslate"><span class="pre">drivers/mtd/skeleton.c</span></code> Skeleton memory technology device drivers</p></li> |
| <li><p><code class="docutils literal notranslate"><span class="pre">drivers/net/skeleton.c</span></code> Skeleton network/Ethernet drivers</p></li> |
| <li><p><code class="docutils literal notranslate"><span class="pre">drivers/usbhost/usbhost_skeleton.c</span></code> Skeleton USB host class driver</p></li> |
| </ul> |
| </section> |
| <section id="drivers-early-initialization"> |
| <h2>Drivers Early Initialization<a class="headerlink" href="#drivers-early-initialization" title="Permalink to this heading"></a></h2> |
| <p>To initialize drivers early in the boot process, the <code class="xref c c-func docutils literal notranslate"><span class="pre">drivers_early_initialize()</span></code> |
| function is introduced. This is particularly beneficial for certain drivers, |
| such as SEGGER SystemView, or others that require initialization before the |
| system is fully operational.</p> |
| <p>It is important to note that during this early initialization phase, |
| system resources are not yet available for use. This includes memory allocation, |
| file systems, and any other system resources.</p> |
| </section> |
| </section> |
| |
| |
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