fcc6ab335b
This interface makes it easy for drivers to register usage of different I/O interruption subclasses without needing to worry about possible other users of the same isc. Signed-off-by: Sebastian Ott <sebott@linux.vnet.ibm.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com> Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
69 lines
1.7 KiB
C
69 lines
1.7 KiB
C
/*
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* Functions for registration of I/O interruption subclasses on s390.
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*
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* Copyright IBM Corp. 2008
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* Authors: Sebastian Ott <sebott@linux.vnet.ibm.com>
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*/
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#include <linux/spinlock.h>
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#include <linux/module.h>
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#include <asm/isc.h>
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static unsigned int isc_refs[MAX_ISC + 1];
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static DEFINE_SPINLOCK(isc_ref_lock);
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/**
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* isc_register - register an I/O interruption subclass.
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* @isc: I/O interruption subclass to register
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*
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* The number of users for @isc is increased. If this is the first user to
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* register @isc, the corresponding I/O interruption subclass mask is enabled.
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*
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* Context:
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* This function must not be called in interrupt context.
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*/
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void isc_register(unsigned int isc)
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{
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if (isc > MAX_ISC) {
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WARN_ON(1);
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return;
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}
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spin_lock(&isc_ref_lock);
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if (isc_refs[isc] == 0)
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ctl_set_bit(6, 31 - isc);
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isc_refs[isc]++;
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spin_unlock(&isc_ref_lock);
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}
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EXPORT_SYMBOL_GPL(isc_register);
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/**
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* isc_unregister - unregister an I/O interruption subclass.
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* @isc: I/O interruption subclass to unregister
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*
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* The number of users for @isc is decreased. If this is the last user to
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* unregister @isc, the corresponding I/O interruption subclass mask is
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* disabled.
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* Note: This function must not be called if isc_register() hasn't been called
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* before by the driver for @isc.
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*
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* Context:
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* This function must not be called in interrupt context.
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*/
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void isc_unregister(unsigned int isc)
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{
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spin_lock(&isc_ref_lock);
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/* check for misuse */
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if (isc > MAX_ISC || isc_refs[isc] == 0) {
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WARN_ON(1);
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goto out_unlock;
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}
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if (isc_refs[isc] == 1)
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ctl_clear_bit(6, 31 - isc);
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isc_refs[isc]--;
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out_unlock:
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spin_unlock(&isc_ref_lock);
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}
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EXPORT_SYMBOL_GPL(isc_unregister);
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