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<!-- Copyright (C) 2003 Red Hat, Inc.                                -->
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><TITLE
>Device Driver Interface to the Kernel</TITLE
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><HR
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><DIV
CLASS="CHAPTER"
><H1
><A
NAME="DEVAPI-DEVICE-DRIVER-INTERFACE-TO-THE-KERNEL">Chapter 18. Device Driver Interface to the Kernel</H1
><DIV
CLASS="TOC"
><DL
><DT
><B
>Table of Contents</B
></DT
><DT
><A
HREF="devapi-device-driver-interface-to-the-kernel.html#DEVAPI-INTERRUPT-MODEL"
>Interrupt Model</A
></DT
><DT
><A
HREF="devapi-synchronization.html"
>Synchronization</A
></DT
><DT
><A
HREF="devapi-smp-support.html"
>SMP Support</A
></DT
><DT
><A
HREF="devapi-device-driver-models.html"
>Device Driver Models</A
></DT
><DT
><A
HREF="devapi-synchronization-levels.html"
>Synchronization Levels</A
></DT
><DT
><A
HREF="devapi-api.html"
>The API</A
></DT
></DL
></DIV
><P
>This chapter describes the API that device drivers may use
to interact with the kernel and HAL. It is primarily concerned with
the control and management of interrupts and the synchronization of
ISRs, DSRs and threads.</P
><P
>The same API will be present in configurations where the kernel
is not present. In this case the functions will be supplied by code
acting directly on the HAL.</P
><DIV
CLASS="SECTION"
><H1
CLASS="SECTION"
><A
NAME="DEVAPI-INTERRUPT-MODEL">Interrupt Model</H1
><P
><SPAN
CLASS="emphasis"
><I
CLASS="EMPHASIS"
>eCos</I
></SPAN
> presents a three level interrupt model to
device drivers. This consists of Interrupt Service Routines (ISRs) that are invoked
in response to a hardware interrupt; Deferred
Service Routines (DSRs) that are invoked in response to a request by
an ISR; and threads that are the clients of the driver. </P
><P
>Hardware interrupts are delivered with minimal intervention to an
ISR. The HAL decodes the hardware source of the interrupt and calls
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
driver API. When it returns, an ISR may request that its DSR should be
scheduled to run.</P
><P
>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
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
driver API calls, including, in particular, being able to call
<TT
CLASS="FUNCTION"
>cyg_drv_cond_signal()</TT
> to wake up waiting
threads.</P
><P
>Finally, threads are able to make all API calls and in particular are
allowed to wait on mutexes and condition variables. </P
><P
>For a device driver to receive interrupts it must first define ISR and
DSR routines as shown below, and then call
<TT
CLASS="FUNCTION"
>cyg_drv_interrupt_create()</TT
>.  Using the handle
returned, the driver must then call
<TT
CLASS="FUNCTION"
>cyg_drv_interrupt_attach()</TT
> to actually attach the
interrupt to the hardware vector.</P
></DIV
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>

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1	28	unneback	`<!-- Copyright (C) 2003 Red Hat, Inc. -->`
2			`<!-- This material may be distributed only subject to the terms -->`
3			`<!-- and conditions set forth in the Open Publication License, v1.0 -->`
4			`<!-- or later (the latest version is presently available at -->`
5			`<!-- http://www.opencontent.org/openpub/). -->`
6			`<!-- Distribution of the work or derivative of the work in any -->`
7			`<!-- standard (paper) book form is prohibited unless prior -->`
8			`<!-- permission is obtained from the copyright holder. -->`
9			`<HTML`
10			`><HEAD`
11			`><TITLE`
12			`>Device Driver Interface to the Kernel</TITLE`
13			`><meta name="MSSmartTagsPreventParsing" content="TRUE">`
14			`<META`
15			`NAME="GENERATOR"`
16			`CONTENT="Modular DocBook HTML Stylesheet Version 1.76b+`
17			`"><LINK`
18			`REL="HOME"`
19			`TITLE="eCos Reference Manual"`
20			`HREF="ecos-ref.html"><LINK`
21			`REL="UP"`
22			`TITLE="I/O Package (Device Drivers)"`
23			`HREF="io.html"><LINK`
24			`REL="PREVIOUS"`
25			`TITLE="Serial testing with ser_filter"`
26			`HREF="io-serial-testing-with-serfilter.html"><LINK`
27			`REL="NEXT"`
28			`TITLE="Synchronization"`
29			`HREF="devapi-synchronization.html"></HEAD`
30			`><BODY`
31			`CLASS="CHAPTER"`
32			`BGCOLOR="#FFFFFF"`
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45			`><TR`
46			`><TH`
47			`COLSPAN="3"`
48			`ALIGN="center"`
49			`>eCos Reference Manual</TH`
50			`></TR`
51			`><TR`
52			`><TD`
53			`WIDTH="10%"`
54			`ALIGN="left"`
55			`VALIGN="bottom"`
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58			`ACCESSKEY="P"`
59			`>Prev</A`
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80			`><DIV`
81			`CLASS="CHAPTER"`
82			`><H1`
83			`><A`
84			`NAME="DEVAPI-DEVICE-DRIVER-INTERFACE-TO-THE-KERNEL">Chapter 18. Device Driver Interface to the Kernel</H1`
85			`><DIV`
86			`CLASS="TOC"`
87			`><DL`
88			`><DT`
89			`><B`
90			`>Table of Contents</B`
91			`></DT`
92			`><DT`
93			`><A`
94			`HREF="devapi-device-driver-interface-to-the-kernel.html#DEVAPI-INTERRUPT-MODEL"`
95			`>Interrupt Model</A`
96			`></DT`
97			`><DT`
98			`><A`
99			`HREF="devapi-synchronization.html"`
100			`>Synchronization</A`
101			`></DT`
102			`><DT`
103			`><A`
104			`HREF="devapi-smp-support.html"`
105			`>SMP Support</A`
106			`></DT`
107			`><DT`
108			`><A`
109			`HREF="devapi-device-driver-models.html"`
110			`>Device Driver Models</A`
111			`></DT`
112			`><DT`
113			`><A`
114			`HREF="devapi-synchronization-levels.html"`
115			`>Synchronization Levels</A`
116			`></DT`
117			`><DT`
118			`><A`
119			`HREF="devapi-api.html"`
120			`>The API</A`
121			`></DT`
122			`></DL`
123			`></DIV`
124			`><P`
125			`>This chapter describes the API that device drivers may use`
126			`to interact with the kernel and HAL. It is primarily concerned with`
127			`the control and management of interrupts and the synchronization of`
128			`ISRs, DSRs and threads.</P`
129			`><P`
130			`>The same API will be present in configurations where the kernel`
131			`is not present. In this case the functions will be supplied by code`
132			`acting directly on the HAL.</P`
133			`><DIV`
134			`CLASS="SECTION"`
135			`><H1`
136			`CLASS="SECTION"`
137			`><A`
138			`NAME="DEVAPI-INTERRUPT-MODEL">Interrupt Model</H1`
139			`><P`
140			`><SPAN`
141			`CLASS="emphasis"`
142			`><I`
143			`CLASS="EMPHASIS"`
144			`>eCos</I`
145			`></SPAN`
146			`> presents a three level interrupt model to`
147			`device drivers. This consists of Interrupt Service Routines (ISRs) that are invoked`
148			`in response to a hardware interrupt; Deferred`
149			`Service Routines (DSRs) that are invoked in response to a request by`
150			`an ISR; and threads that are the clients of the driver. </P`
151			`><P`
152			`>Hardware interrupts are delivered with minimal intervention to an`
153			`ISR. The HAL decodes the hardware source of the interrupt and calls`
154			`the ISR of the attached interrupt object. This ISR may manipulate the`
155			`hardware but is only allowed to make a restricted set of calls on the`
156			`driver API. When it returns, an ISR may request that its DSR should be`
157			`scheduled to run.</P`
158			`><P`
159			`>A DSR will be run when it is safe to do so without interfering with`
160			`the scheduler. Most of the time the DSR will run immediately after the`
161			`ISR, but if the current thread is in the scheduler, it will be delayed`
162			`until the thread is finished. A DSR is allowed to make a larger set of`
163			`driver API calls, including, in particular, being able to call`
164			`<TT`
165			`CLASS="FUNCTION"`
166			`>cyg_drv_cond_signal()</TT`
167			`> to wake up waiting`
168			`threads.</P`
169			`><P`
170			`>Finally, threads are able to make all API calls and in particular are`
171			`allowed to wait on mutexes and condition variables. </P`
172			`><P`
173			`>For a device driver to receive interrupts it must first define ISR and`
174			`DSR routines as shown below, and then call`
175			`<TT`
176			`CLASS="FUNCTION"`
177			`>cyg_drv_interrupt_create()</TT`
178			`>. Using the handle`
179			`returned, the driver must then call`
180			`<TT`
181			`CLASS="FUNCTION"`
182			`>cyg_drv_interrupt_attach()</TT`
183			`> to actually attach the`
184			`interrupt to the hardware vector.</P`
185			`></DIV`
186			`></DIV`
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188			`CLASS="NAVFOOTER"`
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231			`>Serial testing with ser_filter</TD`
232			`><TD`
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251			`>`

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[/] [openrisc/] [trunk/] [rtos/] [ecos-2.0/] [doc/] [html/] [ref/] [devapi-device-driver-interface-to-the-kernel.html] - Blame information for rev 174