<!-- Copyright (C) 2003 Red Hat, Inc. -->
|
<!-- Copyright (C) 2003 Red Hat, Inc. -->
|
<!-- This material may be distributed only subject to the terms -->
|
<!-- This material may be distributed only subject to the terms -->
|
<!-- and conditions set forth in the Open Publication License, v1.0 -->
|
<!-- and conditions set forth in the Open Publication License, v1.0 -->
|
<!-- or later (the latest version is presently available at -->
|
<!-- or later (the latest version is presently available at -->
|
<!-- http://www.opencontent.org/openpub/). -->
|
<!-- http://www.opencontent.org/openpub/). -->
|
<!-- Distribution of the work or derivative of the work in any -->
|
<!-- Distribution of the work or derivative of the work in any -->
|
<!-- standard (paper) book form is prohibited unless prior -->
|
<!-- standard (paper) book form is prohibited unless prior -->
|
<!-- permission is obtained from the copyright holder. -->
|
<!-- permission is obtained from the copyright holder. -->
|
<HTML
|
<HTML
|
><HEAD
|
><HEAD
|
><TITLE
|
><TITLE
|
>Device Driver Interface to the Kernel</TITLE
|
>Device Driver Interface to the Kernel</TITLE
|
><meta name="MSSmartTagsPreventParsing" content="TRUE">
|
><meta name="MSSmartTagsPreventParsing" content="TRUE">
|
<META
|
<META
|
NAME="GENERATOR"
|
NAME="GENERATOR"
|
CONTENT="Modular DocBook HTML Stylesheet Version 1.76b+
|
CONTENT="Modular DocBook HTML Stylesheet Version 1.76b+
|
"><LINK
|
"><LINK
|
REL="HOME"
|
REL="HOME"
|
TITLE="eCos Reference Manual"
|
TITLE="eCos Reference Manual"
|
HREF="ecos-ref.html"><LINK
|
HREF="ecos-ref.html"><LINK
|
REL="UP"
|
REL="UP"
|
TITLE="I/O Package (Device Drivers)"
|
TITLE="I/O Package (Device Drivers)"
|
HREF="io.html"><LINK
|
HREF="io.html"><LINK
|
REL="PREVIOUS"
|
REL="PREVIOUS"
|
TITLE="Serial testing with ser_filter"
|
TITLE="Serial testing with ser_filter"
|
HREF="io-serial-testing-with-serfilter.html"><LINK
|
HREF="io-serial-testing-with-serfilter.html"><LINK
|
REL="NEXT"
|
REL="NEXT"
|
TITLE="Synchronization"
|
TITLE="Synchronization"
|
HREF="devapi-synchronization.html"></HEAD
|
HREF="devapi-synchronization.html"></HEAD
|
><BODY
|
><BODY
|
CLASS="CHAPTER"
|
CLASS="CHAPTER"
|
BGCOLOR="#FFFFFF"
|
BGCOLOR="#FFFFFF"
|
TEXT="#000000"
|
TEXT="#000000"
|
LINK="#0000FF"
|
LINK="#0000FF"
|
VLINK="#840084"
|
VLINK="#840084"
|
ALINK="#0000FF"
|
ALINK="#0000FF"
|
><DIV
|
><DIV
|
CLASS="NAVHEADER"
|
CLASS="NAVHEADER"
|
><TABLE
|
><TABLE
|
SUMMARY="Header navigation table"
|
SUMMARY="Header navigation table"
|
WIDTH="100%"
|
WIDTH="100%"
|
BORDER="0"
|
BORDER="0"
|
CELLPADDING="0"
|
CELLPADDING="0"
|
CELLSPACING="0"
|
CELLSPACING="0"
|
><TR
|
><TR
|
><TH
|
><TH
|
COLSPAN="3"
|
COLSPAN="3"
|
ALIGN="center"
|
ALIGN="center"
|
>eCos Reference Manual</TH
|
>eCos Reference Manual</TH
|
></TR
|
></TR
|
><TR
|
><TR
|
><TD
|
><TD
|
WIDTH="10%"
|
WIDTH="10%"
|
ALIGN="left"
|
ALIGN="left"
|
VALIGN="bottom"
|
VALIGN="bottom"
|
><A
|
><A
|
HREF="io-serial-testing-with-serfilter.html"
|
HREF="io-serial-testing-with-serfilter.html"
|
ACCESSKEY="P"
|
ACCESSKEY="P"
|
>Prev</A
|
>Prev</A
|
></TD
|
></TD
|
><TD
|
><TD
|
WIDTH="80%"
|
WIDTH="80%"
|
ALIGN="center"
|
ALIGN="center"
|
VALIGN="bottom"
|
VALIGN="bottom"
|
></TD
|
></TD
|
><TD
|
><TD
|
WIDTH="10%"
|
WIDTH="10%"
|
ALIGN="right"
|
ALIGN="right"
|
VALIGN="bottom"
|
VALIGN="bottom"
|
><A
|
><A
|
HREF="devapi-synchronization.html"
|
HREF="devapi-synchronization.html"
|
ACCESSKEY="N"
|
ACCESSKEY="N"
|
>Next</A
|
>Next</A
|
></TD
|
></TD
|
></TR
|
></TR
|
></TABLE
|
></TABLE
|
><HR
|
><HR
|
ALIGN="LEFT"
|
ALIGN="LEFT"
|
WIDTH="100%"></DIV
|
WIDTH="100%"></DIV
|
><DIV
|
><DIV
|
CLASS="CHAPTER"
|
CLASS="CHAPTER"
|
><H1
|
><H1
|
><A
|
><A
|
NAME="DEVAPI-DEVICE-DRIVER-INTERFACE-TO-THE-KERNEL">Chapter 18. Device Driver Interface to the Kernel</H1
|
NAME="DEVAPI-DEVICE-DRIVER-INTERFACE-TO-THE-KERNEL">Chapter 18. Device Driver Interface to the Kernel</H1
|
><DIV
|
><DIV
|
CLASS="TOC"
|
CLASS="TOC"
|
><DL
|
><DL
|
><DT
|
><DT
|
><B
|
><B
|
>Table of Contents</B
|
>Table of Contents</B
|
></DT
|
></DT
|
><DT
|
><DT
|
><A
|
><A
|
HREF="devapi-device-driver-interface-to-the-kernel.html#DEVAPI-INTERRUPT-MODEL"
|
HREF="devapi-device-driver-interface-to-the-kernel.html#DEVAPI-INTERRUPT-MODEL"
|
>Interrupt Model</A
|
>Interrupt Model</A
|
></DT
|
></DT
|
><DT
|
><DT
|
><A
|
><A
|
HREF="devapi-synchronization.html"
|
HREF="devapi-synchronization.html"
|
>Synchronization</A
|
>Synchronization</A
|
></DT
|
></DT
|
><DT
|
><DT
|
><A
|
><A
|
HREF="devapi-smp-support.html"
|
HREF="devapi-smp-support.html"
|
>SMP Support</A
|
>SMP Support</A
|
></DT
|
></DT
|
><DT
|
><DT
|
><A
|
><A
|
HREF="devapi-device-driver-models.html"
|
HREF="devapi-device-driver-models.html"
|
>Device Driver Models</A
|
>Device Driver Models</A
|
></DT
|
></DT
|
><DT
|
><DT
|
><A
|
><A
|
HREF="devapi-synchronization-levels.html"
|
HREF="devapi-synchronization-levels.html"
|
>Synchronization Levels</A
|
>Synchronization Levels</A
|
></DT
|
></DT
|
><DT
|
><DT
|
><A
|
><A
|
HREF="devapi-api.html"
|
HREF="devapi-api.html"
|
>The API</A
|
>The API</A
|
></DT
|
></DT
|
></DL
|
></DL
|
></DIV
|
></DIV
|
><P
|
><P
|
>This chapter describes the API that device drivers may use
|
>This chapter describes the API that device drivers may use
|
to interact with the kernel and HAL. It is primarily concerned with
|
to interact with the kernel and HAL. It is primarily concerned with
|
the control and management of interrupts and the synchronization of
|
the control and management of interrupts and the synchronization of
|
ISRs, DSRs and threads.</P
|
ISRs, DSRs and threads.</P
|
><P
|
><P
|
>The same API will be present in configurations where the kernel
|
>The same API will be present in configurations where the kernel
|
is not present. In this case the functions will be supplied by code
|
is not present. In this case the functions will be supplied by code
|
acting directly on the HAL.</P
|
acting directly on the HAL.</P
|
><DIV
|
><DIV
|
CLASS="SECTION"
|
CLASS="SECTION"
|
><H1
|
><H1
|
CLASS="SECTION"
|
CLASS="SECTION"
|
><A
|
><A
|
NAME="DEVAPI-INTERRUPT-MODEL">Interrupt Model</H1
|
NAME="DEVAPI-INTERRUPT-MODEL">Interrupt Model</H1
|
><P
|
><P
|
><SPAN
|
><SPAN
|
CLASS="emphasis"
|
CLASS="emphasis"
|
><I
|
><I
|
CLASS="EMPHASIS"
|
CLASS="EMPHASIS"
|
>eCos</I
|
>eCos</I
|
></SPAN
|
></SPAN
|
> presents a three level interrupt model to
|
> presents a three level interrupt model to
|
device drivers. This consists of Interrupt Service Routines (ISRs) that are invoked
|
device drivers. This consists of Interrupt Service Routines (ISRs) that are invoked
|
in response to a hardware interrupt; Deferred
|
in response to a hardware interrupt; Deferred
|
Service Routines (DSRs) that are invoked in response to a request by
|
Service Routines (DSRs) that are invoked in response to a request by
|
an ISR; and threads that are the clients of the driver. </P
|
an ISR; and threads that are the clients of the driver. </P
|
><P
|
><P
|
>Hardware interrupts are delivered with minimal intervention to an
|
>Hardware interrupts are delivered with minimal intervention to an
|
ISR. The HAL decodes the hardware source of the interrupt and calls
|
ISR. The HAL decodes the hardware source of the interrupt and calls
|
the ISR of the attached interrupt object. This ISR may manipulate the
|
the ISR of the attached interrupt object. This ISR may manipulate the
|
hardware but is only allowed to make a restricted set of calls on the
|
hardware but is only allowed to make a restricted set of calls on the
|
driver API. When it returns, an ISR may request that its DSR should be
|
driver API. When it returns, an ISR may request that its DSR should be
|
scheduled to run.</P
|
scheduled to run.</P
|
><P
|
><P
|
>A DSR will be run when it is safe to do so without interfering with
|
>A DSR will be run when it is safe to do so without interfering with
|
the scheduler. Most of the time the DSR will run immediately after the
|
the scheduler. Most of the time the DSR will run immediately after the
|
ISR, but if the current thread is in the scheduler, it will be delayed
|
ISR, but if the current thread is in the scheduler, it will be delayed
|
until the thread is finished. A DSR is allowed to make a larger set of
|
until the thread is finished. A DSR is allowed to make a larger set of
|
driver API calls, including, in particular, being able to call
|
driver API calls, including, in particular, being able to call
|
<TT
|
<TT
|
CLASS="FUNCTION"
|
CLASS="FUNCTION"
|
>cyg_drv_cond_signal()</TT
|
>cyg_drv_cond_signal()</TT
|
> to wake up waiting
|
> to wake up waiting
|
threads.</P
|
threads.</P
|
><P
|
><P
|
>Finally, threads are able to make all API calls and in particular are
|
>Finally, threads are able to make all API calls and in particular are
|
allowed to wait on mutexes and condition variables. </P
|
allowed to wait on mutexes and condition variables. </P
|
><P
|
><P
|
>For a device driver to receive interrupts it must first define ISR and
|
>For a device driver to receive interrupts it must first define ISR and
|
DSR routines as shown below, and then call
|
DSR routines as shown below, and then call
|
<TT
|
<TT
|
CLASS="FUNCTION"
|
CLASS="FUNCTION"
|
>cyg_drv_interrupt_create()</TT
|
>cyg_drv_interrupt_create()</TT
|
>. Using the handle
|
>. Using the handle
|
returned, the driver must then call
|
returned, the driver must then call
|
<TT
|
<TT
|
CLASS="FUNCTION"
|
CLASS="FUNCTION"
|
>cyg_drv_interrupt_attach()</TT
|
>cyg_drv_interrupt_attach()</TT
|
> to actually attach the
|
> to actually attach the
|
interrupt to the hardware vector.</P
|
interrupt to the hardware vector.</P
|
></DIV
|
></DIV
|
></DIV
|
></DIV
|
><DIV
|
><DIV
|
CLASS="NAVFOOTER"
|
CLASS="NAVFOOTER"
|
><HR
|
><HR
|
ALIGN="LEFT"
|
ALIGN="LEFT"
|
WIDTH="100%"><TABLE
|
WIDTH="100%"><TABLE
|
SUMMARY="Footer navigation table"
|
SUMMARY="Footer navigation table"
|
WIDTH="100%"
|
WIDTH="100%"
|
BORDER="0"
|
BORDER="0"
|
CELLPADDING="0"
|
CELLPADDING="0"
|
CELLSPACING="0"
|
CELLSPACING="0"
|
><TR
|
><TR
|
><TD
|
><TD
|
WIDTH="33%"
|
WIDTH="33%"
|
ALIGN="left"
|
ALIGN="left"
|
VALIGN="top"
|
VALIGN="top"
|
><A
|
><A
|
HREF="io-serial-testing-with-serfilter.html"
|
HREF="io-serial-testing-with-serfilter.html"
|
ACCESSKEY="P"
|
ACCESSKEY="P"
|
>Prev</A
|
>Prev</A
|
></TD
|
></TD
|
><TD
|
><TD
|
WIDTH="34%"
|
WIDTH="34%"
|
ALIGN="center"
|
ALIGN="center"
|
VALIGN="top"
|
VALIGN="top"
|
><A
|
><A
|
HREF="ecos-ref.html"
|
HREF="ecos-ref.html"
|
ACCESSKEY="H"
|
ACCESSKEY="H"
|
>Home</A
|
>Home</A
|
></TD
|
></TD
|
><TD
|
><TD
|
WIDTH="33%"
|
WIDTH="33%"
|
ALIGN="right"
|
ALIGN="right"
|
VALIGN="top"
|
VALIGN="top"
|
><A
|
><A
|
HREF="devapi-synchronization.html"
|
HREF="devapi-synchronization.html"
|
ACCESSKEY="N"
|
ACCESSKEY="N"
|
>Next</A
|
>Next</A
|
></TD
|
></TD
|
></TR
|
></TR
|
><TR
|
><TR
|
><TD
|
><TD
|
WIDTH="33%"
|
WIDTH="33%"
|
ALIGN="left"
|
ALIGN="left"
|
VALIGN="top"
|
VALIGN="top"
|
>Serial testing with ser_filter</TD
|
>Serial testing with ser_filter</TD
|
><TD
|
><TD
|
WIDTH="34%"
|
WIDTH="34%"
|
ALIGN="center"
|
ALIGN="center"
|
VALIGN="top"
|
VALIGN="top"
|
><A
|
><A
|
HREF="io.html"
|
HREF="io.html"
|
ACCESSKEY="U"
|
ACCESSKEY="U"
|
>Up</A
|
>Up</A
|
></TD
|
></TD
|
><TD
|
><TD
|
WIDTH="33%"
|
WIDTH="33%"
|
ALIGN="right"
|
ALIGN="right"
|
VALIGN="top"
|
VALIGN="top"
|
>Synchronization</TD
|
>Synchronization</TD
|
></TR
|
></TR
|
></TABLE
|
></TABLE
|
></DIV
|
></DIV
|
></BODY
|
></BODY
|
></HTML
|
></HTML
|
|
|
