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[S390] cio: introduce isc_(un)register functions. 

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>
This commit is contained in:
Sebastian Ott 2008-07-14 09:59:00 +02:00 committed by Heiko Carstens
parent da7c5af828
commit fcc6ab335b
3 changed files with 76 additions and 2 deletions
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4
drivers/s390/cio/Makefile
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@ -2,8 +2,8 @@
# Makefile for the S/390 common i/o drivers
#
obj-y += airq.o blacklist.o chsc.o cio.o css.o chp.o idset.o scsw.o fcx.o \
itcw.o
obj-y += airq.o blacklist.o chsc.o cio.o css.o chp.o idset.o isc.o scsw.o \
fcx.o itcw.o
ccw_device-objs += device.o device_fsm.o device_ops.o
ccw_device-objs += device_id.o device_pgid.o device_status.o
obj-y += ccw_device.o cmf.o

68
drivers/s390/cio/isc.c Normal file
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@ -0,0 +1,68 @@
/*
* Functions for registration of I/O interruption subclasses on s390.
*
* Copyright IBM Corp. 2008
* Authors: Sebastian Ott <sebott@linux.vnet.ibm.com>
*/
#include <linux/spinlock.h>
#include <linux/module.h>
#include <asm/isc.h>
static unsigned int isc_refs[MAX_ISC + 1];
static DEFINE_SPINLOCK(isc_ref_lock);
/**
* isc_register - register an I/O interruption subclass.
* @isc: I/O interruption subclass to register
*
* The number of users for @isc is increased. If this is the first user to
* register @isc, the corresponding I/O interruption subclass mask is enabled.
*
* Context:
* This function must not be called in interrupt context.
*/
void isc_register(unsigned int isc)
{
if (isc > MAX_ISC) {
WARN_ON(1);
return;
}
spin_lock(&isc_ref_lock);
if (isc_refs[isc] == 0)
ctl_set_bit(6, 31 - isc);
isc_refs[isc]++;
spin_unlock(&isc_ref_lock);
}
EXPORT_SYMBOL_GPL(isc_register);
/**
* isc_unregister - unregister an I/O interruption subclass.
* @isc: I/O interruption subclass to unregister
*
* The number of users for @isc is decreased. If this is the last user to
* unregister @isc, the corresponding I/O interruption subclass mask is
* disabled.
* Note: This function must not be called if isc_register() hasn't been called
* before by the driver for @isc.
*
* Context:
* This function must not be called in interrupt context.
*/
void isc_unregister(unsigned int isc)
{
spin_lock(&isc_ref_lock);
/* check for misuse */
if (isc > MAX_ISC || isc_refs[isc] == 0) {
WARN_ON(1);
goto out_unlock;
}
if (isc_refs[isc] == 1)
ctl_clear_bit(6, 31 - isc);
isc_refs[isc]--;
out_unlock:
spin_unlock(&isc_ref_lock);
}
EXPORT_SYMBOL_GPL(isc_unregister);

6
include/asm-s390/isc.h
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@ -1,6 +1,8 @@
#ifndef _ASM_S390_ISC_H
#define _ASM_S390_ISC_H
#include <linux/types.h>
/*
* I/O interruption subclasses used by drivers.
* Please add all used iscs here so that it is possible to distribute
@ -15,4 +17,8 @@
/* Adapter interrupts. */
#define QDIO_AIRQ_ISC IO_SCH_ISC /* I/O subchannel in qdio mode */
/* Functions for registration of I/O interruption subclasses */
void isc_register(unsigned int isc);
void isc_unregister(unsigned int isc);
#endif /* _ASM_S390_ISC_H */