URL https://opencores.org/ocsvn/openrisc/openrisc/trunk

Subversion Repositories openrisc

[/] [openrisc/] [trunk/] [rtos/] [ecos-2.0/] [doc/] [html/] [ref/] [devapi-synchronization.html] - Blame information for rev 593

Go to most recent revision | Details | Compare with Previous | View Log


<!-- Copyright (C) 2003 Red Hat, Inc.                                -->
<!-- This material may be distributed only subject to the terms      -->
<!-- and conditions set forth in the Open Publication License, v1.0  -->
<!-- or later (the latest version is presently available at          -->
<!-- http://www.opencontent.org/openpub/).                           -->
<!-- Distribution of the work or derivative of the work in any       -->
<!-- standard (paper) book form is prohibited unless prior           -->
<!-- permission is obtained from the copyright holder.               -->
<HTML
><HEAD
><TITLE
>Synchronization</TITLE
><meta name="MSSmartTagsPreventParsing" content="TRUE">
<META
NAME="GENERATOR"
CONTENT="Modular DocBook HTML Stylesheet Version 1.76b+
"><LINK
REL="HOME"
TITLE="eCos Reference Manual"
HREF="ecos-ref.html"><LINK
REL="UP"
TITLE="Device Driver Interface to the Kernel"
HREF="devapi-device-driver-interface-to-the-kernel.html"><LINK
REL="PREVIOUS"
TITLE="Device Driver Interface to the Kernel"
HREF="devapi-device-driver-interface-to-the-kernel.html"><LINK
REL="NEXT"
TITLE="SMP Support"
HREF="devapi-smp-support.html"></HEAD
><BODY
CLASS="SECTION"
BGCOLOR="#FFFFFF"
TEXT="#000000"
LINK="#0000FF"
VLINK="#840084"
ALINK="#0000FF"
><DIV
CLASS="NAVHEADER"
><TABLE
SUMMARY="Header navigation table"
WIDTH="100%"
BORDER="0"
CELLPADDING="0"
CELLSPACING="0"
><TR
><TH
COLSPAN="3"
ALIGN="center"
>eCos Reference Manual</TH
></TR
><TR
><TD
WIDTH="10%"
ALIGN="left"
VALIGN="bottom"
><A
HREF="devapi-device-driver-interface-to-the-kernel.html"
ACCESSKEY="P"
>Prev</A
></TD
><TD
WIDTH="80%"
ALIGN="center"
VALIGN="bottom"
>Chapter 18. Device Driver Interface to the Kernel</TD
><TD
WIDTH="10%"
ALIGN="right"
VALIGN="bottom"
><A
HREF="devapi-smp-support.html"
ACCESSKEY="N"
>Next</A
></TD
></TR
></TABLE
><HR
ALIGN="LEFT"
WIDTH="100%"></DIV
><DIV
CLASS="SECTION"
><H1
CLASS="SECTION"
><A
NAME="DEVAPI-SYNCHRONIZATION">Synchronization</H1
><P
>There are three levels of synchronization supported:</P
><P
></P
><OL
TYPE="1"
><LI
><P
>    Synchronization with ISRs. This normally means disabling
    interrupts to prevent the ISR running during a critical
    section. In an SMP environment, this will also require the use of
    a spinlock to synchronize with ISRs, DSRs or threads running on
    other CPUs.  This is implemented by the
    <TT
CLASS="FUNCTION"
>cyg_drv_isr_lock()</TT
> and
    <TT
CLASS="FUNCTION"
>cyg_drv_isr_unlock()</TT
> functions. This
    mechanism should be used sparingly and for short periods only.
    For finer grained synchronization, individual spinlocks are also
    supplied.
    </P
></LI
><LI
><P
>    Synchronization with DSRs. This will be implemented in the kernel
    by taking the scheduler lock to prevent DSRs running during
    critical sections. In non-kernel configurations it will be
    implemented by non-kernel code. This is implemented by the
    <TT
CLASS="FUNCTION"
>cyg_drv_dsr_lock()</TT
> and
    <TT
CLASS="FUNCTION"
>cyg_drv_dsr_unlock()</TT
> functions. As with ISR
    synchronization, this mechanism should be used sparingly. Only
    DSRs and threads may use this synchronization mechanism, ISRs are
    not allowed to do this.
    </P
></LI
><LI
><P
>    Synchronization with threads. This is implemented with mutexes
    and condition variables. Only threads may lock the mutexes and
    wait on the condition variables, although DSRs may signal
    condition variables.
    </P
></LI
></OL
><P
>Any data that is accessed from more than one level must be protected
against concurrent access. Data that is accessed by ISRs must be
protected with the ISR lock, or a spinlock at all times,
<SPAN
CLASS="emphasis"
><I
CLASS="EMPHASIS"
>even in ISRs</I
></SPAN
>. Data that is shared between DSRs
and threads should be protected with the DSR lock. Data that is only
accessed by threads must be protected with mutexes.</P
></DIV
><DIV
CLASS="NAVFOOTER"
><HR
ALIGN="LEFT"
WIDTH="100%"><TABLE
SUMMARY="Footer navigation table"
WIDTH="100%"
BORDER="0"
CELLPADDING="0"
CELLSPACING="0"
><TR
><TD
WIDTH="33%"
ALIGN="left"
VALIGN="top"
><A
HREF="devapi-device-driver-interface-to-the-kernel.html"
ACCESSKEY="P"
>Prev</A
></TD
><TD
WIDTH="34%"
ALIGN="center"
VALIGN="top"
><A
HREF="ecos-ref.html"
ACCESSKEY="H"
>Home</A
></TD
><TD
WIDTH="33%"
ALIGN="right"
VALIGN="top"
><A
HREF="devapi-smp-support.html"
ACCESSKEY="N"
>Next</A
></TD
></TR
><TR
><TD
WIDTH="33%"
ALIGN="left"
VALIGN="top"
>Device Driver Interface to the Kernel</TD
><TD
WIDTH="34%"
ALIGN="center"
VALIGN="top"
><A
HREF="devapi-device-driver-interface-to-the-kernel.html"
ACCESSKEY="U"
>Up</A
></TD
><TD
WIDTH="33%"
ALIGN="right"
VALIGN="top"
>SMP Support</TD
></TR
></TABLE
></DIV
></BODY
></HTML
>

Line No.	Rev	Author	Line
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			`>Synchronization</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="Device Driver Interface to the Kernel"`
23			`HREF="devapi-device-driver-interface-to-the-kernel.html"><LINK`
24			`REL="PREVIOUS"`
25			`TITLE="Device Driver Interface to the Kernel"`
26			`HREF="devapi-device-driver-interface-to-the-kernel.html"><LINK`
27			`REL="NEXT"`
28			`TITLE="SMP Support"`
29			`HREF="devapi-smp-support.html"></HEAD`
30			`><BODY`
31			`CLASS="SECTION"`
32			`BGCOLOR="#FFFFFF"`
33			`TEXT="#000000"`
34			`LINK="#0000FF"`
35			`VLINK="#840084"`
36			`ALINK="#0000FF"`
37			`><DIV`
38			`CLASS="NAVHEADER"`
39			`><TABLE`
40			`SUMMARY="Header navigation table"`
41			`WIDTH="100%"`
42			`BORDER="0"`
43			`CELLPADDING="0"`
44			`CELLSPACING="0"`
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"`
56			`><A`
57			`HREF="devapi-device-driver-interface-to-the-kernel.html"`
58			`ACCESSKEY="P"`
59			`>Prev</A`
60			`></TD`
61			`><TD`
62			`WIDTH="80%"`
63			`ALIGN="center"`
64			`VALIGN="bottom"`
65			`>Chapter 18. Device Driver Interface to the Kernel</TD`
66			`><TD`
67			`WIDTH="10%"`
68			`ALIGN="right"`
69			`VALIGN="bottom"`
70			`><A`
71			`HREF="devapi-smp-support.html"`
72			`ACCESSKEY="N"`
73			`>Next</A`
74			`></TD`
75			`></TR`
76			`></TABLE`
77			`><HR`
78			`ALIGN="LEFT"`
79			`WIDTH="100%"></DIV`
80			`><DIV`
81			`CLASS="SECTION"`
82			`><H1`
83			`CLASS="SECTION"`
84			`><A`
85			`NAME="DEVAPI-SYNCHRONIZATION">Synchronization</H1`
86			`><P`
87			`>There are three levels of synchronization supported:</P`
88			`><P`
89			`></P`
90			`><OL`
91			`TYPE="1"`
92			`><LI`
93			`><P`
94			`> Synchronization with ISRs. This normally means disabling`
95			`interrupts to prevent the ISR running during a critical`
96			`section. In an SMP environment, this will also require the use of`
97			`a spinlock to synchronize with ISRs, DSRs or threads running on`
98			`other CPUs. This is implemented by the`
99			`<TT`
100			`CLASS="FUNCTION"`
101			`>cyg_drv_isr_lock()</TT`
102			`> and`
103			`<TT`
104			`CLASS="FUNCTION"`
105			`>cyg_drv_isr_unlock()</TT`
106			`> functions. This`
107			`mechanism should be used sparingly and for short periods only.`
108			`For finer grained synchronization, individual spinlocks are also`
109			`supplied.`
110			`</P`
111			`></LI`
112			`><LI`
113			`><P`
114			`> Synchronization with DSRs. This will be implemented in the kernel`
115			`by taking the scheduler lock to prevent DSRs running during`
116			`critical sections. In non-kernel configurations it will be`
117			`implemented by non-kernel code. This is implemented by the`
118			`<TT`
119			`CLASS="FUNCTION"`
120			`>cyg_drv_dsr_lock()</TT`
121			`> and`
122			`<TT`
123			`CLASS="FUNCTION"`
124			`>cyg_drv_dsr_unlock()</TT`
125			`> functions. As with ISR`
126			`synchronization, this mechanism should be used sparingly. Only`
127			`DSRs and threads may use this synchronization mechanism, ISRs are`
128			`not allowed to do this.`
129			`</P`
130			`></LI`
131			`><LI`
132			`><P`
133			`> Synchronization with threads. This is implemented with mutexes`
134			`and condition variables. Only threads may lock the mutexes and`
135			`wait on the condition variables, although DSRs may signal`
136			`condition variables.`
137			`</P`
138			`></LI`
139			`></OL`
140			`><P`
141			`>Any data that is accessed from more than one level must be protected`
142			`against concurrent access. Data that is accessed by ISRs must be`
143			`protected with the ISR lock, or a spinlock at all times,`
144			`<SPAN`
145			`CLASS="emphasis"`
146			`><I`
147			`CLASS="EMPHASIS"`
148			`>even in ISRs</I`
149			`></SPAN`
150			`>. Data that is shared between DSRs`
151			`and threads should be protected with the DSR lock. Data that is only`
152			`accessed by threads must be protected with mutexes.</P`
153			`></DIV`
154			`><DIV`
155			`CLASS="NAVFOOTER"`
156			`><HR`
157			`ALIGN="LEFT"`
158			`WIDTH="100%"><TABLE`
159			`SUMMARY="Footer navigation table"`
160			`WIDTH="100%"`
161			`BORDER="0"`
162			`CELLPADDING="0"`
163			`CELLSPACING="0"`
164			`><TR`
165			`><TD`
166			`WIDTH="33%"`
167			`ALIGN="left"`
168			`VALIGN="top"`
169			`><A`
170			`HREF="devapi-device-driver-interface-to-the-kernel.html"`
171			`ACCESSKEY="P"`
172			`>Prev</A`
173			`></TD`
174			`><TD`
175			`WIDTH="34%"`
176			`ALIGN="center"`
177			`VALIGN="top"`
178			`><A`
179			`HREF="ecos-ref.html"`
180			`ACCESSKEY="H"`
181			`>Home</A`
182			`></TD`
183			`><TD`
184			`WIDTH="33%"`
185			`ALIGN="right"`
186			`VALIGN="top"`
187			`><A`
188			`HREF="devapi-smp-support.html"`
189			`ACCESSKEY="N"`
190			`>Next</A`
191			`></TD`
192			`></TR`
193			`><TR`
194			`><TD`
195			`WIDTH="33%"`
196			`ALIGN="left"`
197			`VALIGN="top"`
198			`>Device Driver Interface to the Kernel</TD`
199			`><TD`
200			`WIDTH="34%"`
201			`ALIGN="center"`
202			`VALIGN="top"`
203			`><A`
204			`HREF="devapi-device-driver-interface-to-the-kernel.html"`
205			`ACCESSKEY="U"`
206			`>Up</A`
207			`></TD`
208			`><TD`
209			`WIDTH="33%"`
210			`ALIGN="right"`
211			`VALIGN="top"`
212			`>SMP Support</TD`
213			`></TR`
214			`></TABLE`
215			`></DIV`
216			`></BODY`
217			`></HTML`
218			`>`

Browse

Tools

Subversion Repositories openrisc

[/] [openrisc/] [trunk/] [rtos/] [ecos-2.0/] [doc/] [html/] [ref/] [devapi-synchronization.html] - Blame information for rev 593