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<!-- 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>The API</TITLE><meta name="MSSmartTagsPreventParsing" content="TRUE"><METANAME="GENERATOR"CONTENT="Modular DocBook HTML Stylesheet Version 1.76b+"><LINKREL="HOME"TITLE="eCos Reference Manual"HREF="ecos-ref.html"><LINKREL="UP"TITLE="Device Driver Interface to the Kernel"HREF="devapi-device-driver-interface-to-the-kernel.html"><LINKREL="PREVIOUS"TITLE="Synchronization Levels"HREF="devapi-synchronization-levels.html"><LINKREL="NEXT"TITLE="File System Support Infrastructure"HREF="fileio.html"></HEAD><BODYCLASS="SECTION"BGCOLOR="#FFFFFF"TEXT="#000000"LINK="#0000FF"VLINK="#840084"ALINK="#0000FF"><DIVCLASS="NAVHEADER"><TABLESUMMARY="Header navigation table"WIDTH="100%"BORDER="0"CELLPADDING="0"CELLSPACING="0"><TR><THCOLSPAN="3"ALIGN="center">eCos Reference Manual</TH></TR><TR><TDWIDTH="10%"ALIGN="left"VALIGN="bottom"><AHREF="devapi-synchronization-levels.html"ACCESSKEY="P">Prev</A></TD><TDWIDTH="80%"ALIGN="center"VALIGN="bottom">Chapter 18. Device Driver Interface to the Kernel</TD><TDWIDTH="10%"ALIGN="right"VALIGN="bottom"><AHREF="fileio.html"ACCESSKEY="N">Next</A></TD></TR></TABLE><HRALIGN="LEFT"WIDTH="100%"></DIV><DIVCLASS="SECTION"><H1CLASS="SECTION"><ANAME="DEVAPI-API">The API</H1><P>This section details the Driver KernelInterface. Note that most of these functions are identical to Kernel CAPI calls, and will in most configurations be wrappers for them. Innon-kernel configurations they will be supported directly by the HAL,or by code to emulate the required behavior.</P><P>This API is defined in the header file<TTCLASS="FILENAME"><cyg/hal/drv_api.h></TT>.</P><DIVCLASS="SECTION"><H2CLASS="SECTION"><ANAME="AEN11310">cyg_drv_isr_lock</H2><P></P><DIVCLASS="VARIABLELIST"><DL><DT>Function:</DT><DD><TABLEBORDER="5"BGCOLOR="#E0E0F0"WIDTH="70%"><TR><TD><PRECLASS="PROGRAMLISTING">void cyg_drv_isr_lock()</PRE></TD></TR></TABLE></DD><DT>Arguments:</DT><DD><P>None</P></DD><DT>Result:</DT><DD><P>None </P></DD><DT>Level:</DT><DD><P>ISR</P></DD><DT>Description:</DT><DD><P> Disables delivery of interrupts, preventing all ISRs running. This function maintains a counter of the number of times it is called. </P></DD></DL></DIV></DIV><DIVCLASS="SECTION"><H2CLASS="SECTION"><ANAME="AEN11333">cyg_drv_isr_unlock</H2><P></P><DIVCLASS="VARIABLELIST"><DL><DT>Function:</DT><DD><TABLEBORDER="5"BGCOLOR="#E0E0F0"WIDTH="70%"><TR><TD><PRECLASS="PROGRAMLISTING">void cyg_drv_isr_unlock()</PRE></TD></TR></TABLE></DD><DT>Arguments:</DT><DD><P>None</P></DD><DT>Result:</DT><DD><P>None </P></DD><DT>Level:</DT><DD><P>ISR</P></DD><DT>Description:</DT><DD><P>Re-enables delivery of interrupts, allowing ISRs to run. This function decrements the counter maintained by <TTCLASS="FUNCTION">cyg_drv_isr_lock()</TT>, and only re-allows interrupts when it goes to zero. </P></DD></DL></DIV></DIV><DIVCLASS="SECTION"><H2CLASS="SECTION"><ANAME="AEN11357">cyg_drv_spinlock_init</H2><P></P><DIVCLASS="VARIABLELIST"><DL><DT>Function:</DT><DD><TABLEBORDER="5"BGCOLOR="#E0E0F0"WIDTH="70%"><TR><TD><PRECLASS="PROGRAMLISTING">void cyg_drv_spinlock_init(cyg_spinlock_t *lock, cyg_bool_t locked )</PRE></TD></TR></TABLE></DD><DT>Arguments:</DT><DD><P><TTCLASS="PARAMETER"><I>lock</I></TT> - pointer to spinlock to initialize</P><P><TTCLASS="PARAMETER"><I>locked</I></TT> - initial state of lock</P></DD><DT>Result:</DT><DD><P>None</P></DD><DT>Level:</DT><DD><P>Thread</P></DD><DT>Description:</DT><DD><P> Initialize a spinlock. The <TTCLASS="PARAMETER"><I>locked</I></TT> argument indicates how the spinlock should be initialized: <TTCLASS="LITERAL">TRUE</TT> for locked or <TTCLASS="LITERAL">FALSE</TT> for unlocked state. </P></DD></DL></DIV></DIV><DIVCLASS="SECTION"><H2CLASS="SECTION"><ANAME="AEN11386">cyg_drv_spinlock_destroy</H2><P></P><DIVCLASS="VARIABLELIST"><DL><DT>Function:</DT><DD><TABLEBORDER="5"BGCOLOR="#E0E0F0"WIDTH="70%"><TR><TD><PRECLASS="PROGRAMLISTING">void cyg_drv_spinlock_destroy(cyg_spinlock_t *lock )</PRE></TD></TR></TABLE></DD><DT>Arguments:</DT><DD><P><TTCLASS="PARAMETER"><I>lock</I></TT> - pointer to spinlock destroy</P></DD><DT>Result:</DT><DD><P>None</P></DD><DT>Level:</DT><DD><P>Thread</P></DD><DT>Description:</DT><DD><P> Destroy a spinlock that is no longer of use. There should be no CPUs attempting to claim the lock at the time this function is called, otherwise the behavior is undefined. </P></DD></DL></DIV></DIV><DIVCLASS="SECTION"><H2CLASS="SECTION"><ANAME="AEN11410">cyg_drv_spinlock_spin</H2><P></P><DIVCLASS="VARIABLELIST"><DL><DT>Function:</DT><DD><TABLEBORDER="5"BGCOLOR="#E0E0F0"WIDTH="70%"><TR><TD><PRECLASS="PROGRAMLISTING">void cyg_drv_spinlock_spin(cyg_spinlock_t *lock )</PRE></TD></TR></TABLE></DD><DT>Arguments:</DT><DD><P><TTCLASS="PARAMETER"><I>lock</I></TT> - pointer to spinlock to claim</P></DD><DT>Result:</DT><DD><P>None</P></DD><DT>Level:</DT><DD><P>ISR</P></DD><DT>Description:</DT><DD><P> Claim a spinlock, waiting in a busy loop until it is available. Wherever this is called from, this operation effectively pauses the CPU until it succeeds. This operations should therefore be used sparingly, and in situations where deadlocks/livelocks cannot occur. Also see <TTCLASS="FUNCTION">cyg_drv_spinlock_spin_intsave()</TT>. </P></DD></DL></DIV></DIV><DIVCLASS="SECTION"><H2CLASS="SECTION"><ANAME="AEN11435">cyg_drv_spinlock_clear</H2><P></P><DIVCLASS="VARIABLELIST"><DL><DT>Function:</DT><DD><TABLEBORDER="5"BGCOLOR="#E0E0F0"WIDTH="70%"><TR><TD><PRECLASS="PROGRAMLISTING">void cyg_drv_spinlock_clear(cyg_spinlock_t *lock )</PRE></TD></TR></TABLE></DD><DT>Arguments:</DT><DD><P><TTCLASS="PARAMETER"><I>lock</I></TT> - pointer to spinlock to clear </P></DD><DT>Result:</DT><DD><P>None</P></DD><DT>Level:</DT><DD><P>ISR</P></DD><DT>Description:</DT><DD><P> Clear a spinlock. This clears the spinlock and allows another CPU to claim it. If there is more than one CPU waiting in <TTCLASS="FUNCTION">cyg_drv_spinlock_spin()</TT> then just one of them will be allowed to proceed. </P></DD></DL></DIV></DIV><DIVCLASS="SECTION"><H2CLASS="SECTION"><ANAME="AEN11460">cyg_drv_spinlock_try</H2><P></P><DIVCLASS="VARIABLELIST"><DL><DT>Function:</DT><DD><TABLEBORDER="5"BGCOLOR="#E0E0F0"WIDTH="70%"><TR><TD><PRECLASS="PROGRAMLISTING">cyg_bool_t cyg_drv_spinlock_try(cyg_spinlock_t *lock )</PRE></TD></TR></TABLE></DD><DT>Arguments:</DT><DD><P><TTCLASS="PARAMETER"><I>lock</I></TT> - pointer to spinlock to try</P></DD><DT>Result:</DT><DD><P><TTCLASS="LITERAL">TRUE</TT> if the spinlock was claimed, <TTCLASS="LITERAL">FALSE</TT> otherwise.</P></DD><DT>Level:</DT><DD><P>ISR</P></DD><DT>Description:</DT><DD><P> Try to claim the spinlock without waiting. If the spinlock could be claimed immediately then <TTCLASS="LITERAL">TRUE</TT> is returned. If the spinlock is already claimed then the result is <TTCLASS="LITERAL">FALSE</TT>. </P></DD></DL></DIV></DIV><DIVCLASS="SECTION"><H2CLASS="SECTION"><ANAME="AEN11488">cyg_drv_spinlock_test</H2><P></P><DIVCLASS="VARIABLELIST"><DL><DT>Function:</DT><DD><TABLEBORDER="5"BGCOLOR="#E0E0F0"WIDTH="70%"><TR><TD><PRECLASS="PROGRAMLISTING">cyg_bool_t cyg_drv_spinlock_test(cyg_spinlock_t *lock )</PRE></TD></TR></TABLE></DD><DT>Arguments:</DT><DD><P><TTCLASS="PARAMETER"><I>lock</I></TT> - pointer to spinlock to test</P></DD><DT>Result:</DT><DD><P><TTCLASS="LITERAL">TRUE</TT> if the spinlock is available, <TTCLASS="LITERAL">FALSE</TT> otherwise.</P></DD><DT>Level:</DT><DD><P>ISR</P></DD><DT>Description:</DT><DD><P> Inspect the state of the spinlock. If the spinlock is not locked then the result is <TTCLASS="LITERAL">TRUE</TT>. If it is locked then the result will be <TTCLASS="LITERAL">FALSE</TT>. </P></DD></DL></DIV></DIV><DIVCLASS="SECTION"><H2CLASS="SECTION"><ANAME="AEN11516">cyg_drv_spinlock_spin_intsave</H2><P></P><DIVCLASS="VARIABLELIST"><DL><DT>Function:</DT><DD><TABLEBORDER="5"BGCOLOR="#E0E0F0"WIDTH="70%"><TR><TD><PRECLASS="PROGRAMLISTING">void cyg_drv_spinlock_spin_intsave(cyg_spinlock_t *lock, cyg_addrword_t *istate )</PRE></TD></TR></TABLE></DD><DT>Arguments:</DT><DD><P><TTCLASS="PARAMETER"><I>lock</I></TT> - pointer to spinlock to claim</P><P><TTCLASS="PARAMETER"><I>istate</I></TT> - pointer to interrupt state save location</P></DD><DT>Result:</DT><DD><P>None</P></DD><DT>Level:</DT><DD><P>ISR</P></DD><DT>Description:</DT><DD><P> This function behaves exactly like <TTCLASS="FUNCTION">cyg_drv_spinlock_spin()</TT> except that it also disables interrupts before attempting to claim the lock. The current interrupt enable state is saved in <TTCLASS="PARAMETER"><I>*istate</I></TT>. Interrupts remain disabled once the spinlock had been claimed and must be restored by calling <TTCLASS="FUNCTION">cyg_drv_spinlock_clear_intsave()</TT>. </P><P> In general, device drivers should use this function to claim and release spinlocks rather than the non-<TTCLASS="FUNCTION">_intsave()</TT> variants, to ensure proper exclusion with code running on both other CPUs and this CPU. </P></DD></DL></DIV></DIV><DIVCLASS="SECTION"><H2CLASS="SECTION"><ANAME="AEN11547">cyg_drv_spinlock_clear_intsave</H2><P></P><DIVCLASS="VARIABLELIST"><DL><DT>Function:</DT><DD><TABLEBORDER="5"BGCOLOR="#E0E0F0"WIDTH="70%"><TR><TD><PRECLASS="PROGRAMLISTING">void cyg_drv_spinlock_clear_intsave( cyg_spinlock_t *lock, cyg_addrword_t istate )</PRE></TD></TR></TABLE></DD><DT>Arguments:</DT><DD><P><TTCLASS="PARAMETER"><I>lock</I></TT> - pointer to spinlock to clear </P><P><TTCLASS="PARAMETER"><I>istate</I></TT> - interrupt state to restore </P></DD><DT>Result:</DT><DD><P>None</P></DD><DT>Level:</DT><DD><P>ISR</P></DD><DT>Description:</DT><DD><P> This function behaves exactly like <TTCLASS="FUNCTION">cyg_drv_spinlock_clear()</TT> except that it also restores an interrupt state saved by <TTCLASS="FUNCTION">cyg_drv_spinlock_spin_intsave()</TT>. The <TTCLASS="PARAMETER"><I>istate</I></TT> argument must have been initialized by a previous call to <TTCLASS="FUNCTION">cyg_drv_spinlock_spin_intsave()</TT>. </P></DD></DL></DIV></DIV><DIVCLASS="SECTION"><H2CLASS="SECTION"><ANAME="AEN11577">cyg_drv_dsr_lock</H2><P></P><DIVCLASS="VARIABLELIST"><DL><DT>Function:</DT><DD><TABLEBORDER="5"BGCOLOR="#E0E0F0"WIDTH="70%"><TR><TD><PRECLASS="PROGRAMLISTING">void cyg_drv_dsr_lock()</PRE></TD></TR></TABLE></DD><DT>Arguments:</DT><DD><P>None</P></DD><DT>Result:</DT><DD><P>None </P></DD><DT>Level:</DT><DD><P>DSR</P></DD><DT>Description:</DT><DD><P>Disables scheduling of DSRs. This function maintains a counter of the number of times it has been called. </P></DD></DL></DIV></DIV><DIVCLASS="SECTION"><H2CLASS="SECTION"><ANAME="AEN11600">cyg_drv_dsr_unlock</H2><P></P><DIVCLASS="VARIABLELIST"><DL><DT>Function:</DT><DD><TABLEBORDER="5"BGCOLOR="#E0E0F0"WIDTH="70%"><TR><TD><PRECLASS="PROGRAMLISTING">void cyg_drv_dsr_unlock()</PRE></TD></TR></TABLE></DD><DT>Arguments:</DT><DD><P>None</P></DD><DT>Result:</DT><DD><P> </P><P>None </P></DD><DT>Level:</DT><DD><P>DSR</P></DD><DT>Description:</DT><DD><P>Re-enables scheduling of DSRs. This function decrements the counter incremented by <TTCLASS="FUNCTION">cyg_drv_dsr_lock()</TT>. DSRs are only allowed to be delivered when the counter goes to zero. </P></DD></DL></DIV></DIV><DIVCLASS="SECTION"><H2CLASS="SECTION"><ANAME="AEN11625">cyg_drv_mutex_init</H2><P></P><DIVCLASS="VARIABLELIST"><DL><DT>Function:</DT><DD><TABLEBORDER="5"BGCOLOR="#E0E0F0"WIDTH="70%"><TR><TD><PRECLASS="PROGRAMLISTING">void cyg_drv_mutex_init(cyg_drv_mutex *mutex)</PRE></TD></TR></TABLE></DD><DT>Arguments:</DT><DD><P><TTCLASS="PARAMETER"><I>mutex</I></TT> - pointer to mutex to initialize</P></DD><DT>Result:</DT><DD><P>None </P></DD><DT>Level:</DT⌨️ 快捷键说明
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