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    10 <!DOCTYPE concept

    11   PUBLIC "-//OASIS//DTD DITA Concept//EN" "concept.dtd">

    12 <concept id="GUID-A849B353-76E5-5AD6-851A-AF18C66AED48" xml:lang="en"><title>Generic

    13 Driver Support Overview</title><shortdesc>Generic driver related concepts in Symbian platform. </shortdesc><prolog><metadata><keywords/></metadata></prolog><conbody>

    14 <section id="GUID-DBF1C87D-7360-54B7-8658-B6659BF77F06-GENID-1-7-1-14-1-1-12-1-4-1-3-1"><title>Architecture</title> <p>The

    15 role of a generic device driver is to give a user-side application access

    16 to peripheral resources without exposing the operation of the underlying hardware.

    17 A device driver is effectively an add-on to the kernel, and implements a polymorphic

    18 interface defined by the kernel. It resides on the kernel side and therefore

    19 has the same access rights, uses the kernel heap and links to the kernel,

    20 so that it can call kernel functions. Typically, hardware indicates completion

    21 of an operation by generating an interrupt. This is handled by an Interrupt

    22 Service Routine (ISR) provided by the driver. An ISR is restricted in what

    23 it can do, and must complete quickly. So it is normal for it to schedule a

    24 Delayed Function Call (DFC) which at some later time runs in the context of

    25 a kernel-side thread. Device driver services are generally asynchronous. A

    26 device driver includes: </p> <ul>

    27 <li id="GUID-DE0F5D5C-B3C2-547D-BE5B-EA80FE290A20"><p>A user-side API </p> </li>

    28 <li id="GUID-33122E07-9C29-5138-8FBD-D8B34195091D"><p>Two kernel-side DLLs,

    29 each of which exports a single factory function at ordinal 1 to create the

    30 necessary kernel-side objects, namely </p> <ul>

    31 <li id="GUID-33F58387-8EB1-559B-9410-F06F76DA436C"><p>Logical device driver

    32 DLL with a file name extension <codeph>.ldd</codeph> </p> </li>

    33 <li id="GUID-ED88F823-7883-5BEC-8E50-728F59901D05"><p>Physical device driver

    34 DLL with a file name extension .pdd </p> </li>

    35 </ul> </li>

    36 </ul> </section>

    37 <section id="GUID-A51AA612-F9DC-4A57-A110-BABB0002B624"><title>Components</title> <p>The

    38 following components make up the generic driver support collection: </p> <ul>

    39 <li id="GUID-10D21882-F873-5A7A-BF95-1099CF2D1105"><p>Generic Board Support

    40 Packages </p> </li>

    41 <li id="GUID-3537A6C7-9DA1-57D8-9C41-BA15A7647979"><p>Media Drivers </p> </li>

    42 <li id="GUID-0DDB7C2E-2231-5C12-9650-5BEA71A21A89"><p>SD Card 3C Driver </p> </li>

    43 <li id="GUID-60CCAEA4-0260-55DB-AD7E-4565C9866A9F"><p>SD Card 4C Driver </p> </li>

    44 <li id="GUID-D196EB31-A9A9-591D-B193-D51A51CBF36C"><p>System On Chip ASSP </p> </li>

    45 </ul> </section>

    46 <section id="GUID-B6DCB613-80AF-416C-A8E2-3321CE02C1C6"><title>Using Generic

    47 Driver Support</title> <ul>

    48 <li id="GUID-F905C135-E1B0-5AB1-A131-5136CC4B45F7"><p>Generic Board Support

    49 Packages - Generic Board Support Packages provides generic code for DMA framework,

    50 power management and digitizer. </p> </li>

    51 <li id="GUID-44105C97-F2CD-597C-8645-2A3556B711AE"><p>Media Drivers - The

    52 Media Drivers collection provides the physical device drivers, called media

    53 drivers, and associated libraries that manage storage media hardware. Some

    54 media drivers have platform specific layers that a base port can implement

    55 for particular types of storage hardware. </p> </li>

    56 <li id="GUID-1A009040-46D7-5BE9-A31E-CECBF3FC0DF4"><p>SD Card 3C Driver -

    57 SD Card 3C Driver provides media drivers and generic (PIL) parts of the stack

    58 for accessing Secure Digital flash memory cards. </p> </li>

    59 <li id="GUID-813297BC-3DC3-519A-9193-EACB6DDFBA2F"><p>SD Card 4C Driver -

    60 SD Card 4C Driver provides media drivers and generic (PIL) parts of the stack

    61 for accessing 4C type Secure Digital flash memory cards. </p> </li>

    62 <li id="GUID-A424393A-EDA6-524A-9117-6AFB8595EF2D"><p>System On Chip ASSP

    63 - System On Chip ASSP contains source for common hardware peripherals that

    64 may be used by multiple BSPs. </p> </li>

    65 </ul><note> 4C and 3C type SD card drivers are split, as they are available

    66 under different licenses.</note> </section>

    67 </conbody><related-links>

    68 <link href="GUID-52371DAB-A231-558C-B3E6-220DAAEE566B.dita#GUID-52371DAB-A231-558C-B3E6-220DAAEE566B/GUID-D25228C5-D51E-54A3-A5D0-0B68A9E8E7C8">

    69 <linktext>Logical Device                 Drivers and Generic Driver Support</linktext>

    70 </link>

    71 </related-links></concept>