fiq.c
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/*
* linux/arch/arm/kernel/fiq.c
*
* Copyright (C) 1998 Russell King
* Copyright (C) 1998, 1999 Phil Blundell
*
* FIQ support written by Philip Blundell <philb@gnu.org>, 1998.
*
* FIQ support re-written by Russell King to be more generic
*
* We now properly support a method by which the FIQ handlers can
* be stacked onto the vector. We still do not support sharing
* the FIQ vector itself.
*
* Operation is as follows:
* 1. Owner A claims FIQ:
* - default_fiq relinquishes control.
* 2. Owner A:
* - inserts code.
* - sets any registers,
* - enables FIQ.
* 3. Owner B claims FIQ:
* - if owner A has a relinquish function.
* - disable FIQs.
* - saves any registers.
* - returns zero.
* 4. Owner B:
* - inserts code.
* - sets any registers,
* - enables FIQ.
* 5. Owner B releases FIQ:
* - Owner A is asked to reacquire FIQ:
* - inserts code.
* - restores saved registers.
* - enables FIQ.
* 6. Goto 3
*/
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/seq_file.h>
#include <asm/cacheflush.h>
#include <asm/cp15.h>
#include <asm/fiq.h>
#include <asm/irq.h>
#include <asm/traps.h>
#define FIQ_OFFSET ({ \
extern void *vector_fiq_offset; \
(unsigned)&vector_fiq_offset; \
})
static unsigned long no_fiq_insn;
/* Default reacquire function
* - we always relinquish FIQ control
* - we always reacquire FIQ control
*/
static int fiq_def_op(void *ref, int relinquish)
{
if (!relinquish)
set_fiq_handler(&no_fiq_insn, sizeof(no_fiq_insn));
return 0;
}
static struct fiq_handler default_owner = {
.name = "default",
.fiq_op = fiq_def_op,
};
static struct fiq_handler *current_fiq = &default_owner;
int show_fiq_list(struct seq_file *p, int prec)
{
if (current_fiq != &default_owner)
seq_printf(p, "%*s: %s\n", prec, "FIQ",
current_fiq->name);
return 0;
}
void set_fiq_handler(void *start, unsigned int length)
{
void *base = vectors_page;
unsigned offset = FIQ_OFFSET;
memcpy(base + offset, start, length);
if (!cache_is_vipt_nonaliasing())
flush_icache_range((unsigned long)base + offset, offset +
length);
flush_icache_range(0xffff0000 + offset, 0xffff0000 + offset + length);
}
int claim_fiq(struct fiq_handler *f)
{
int ret = 0;
if (current_fiq) {
ret = -EBUSY;
if (current_fiq->fiq_op != NULL)
ret = current_fiq->fiq_op(current_fiq->dev_id, 1);
}
if (!ret) {
f->next = current_fiq;
current_fiq = f;
}
return ret;
}
void release_fiq(struct fiq_handler *f)
{
if (current_fiq != f) {
printk(KERN_ERR "%s FIQ trying to release %s FIQ\n",
f->name, current_fiq->name);
dump_stack();
return;
}
do
current_fiq = current_fiq->next;
while (current_fiq->fiq_op(current_fiq->dev_id, 0));
}
static int fiq_start;
void enable_fiq(int fiq)
{
enable_irq(fiq + fiq_start);
}
void disable_fiq(int fiq)
{
disable_irq(fiq + fiq_start);
}
EXPORT_SYMBOL(set_fiq_handler);
EXPORT_SYMBOL(__set_fiq_regs); /* defined in fiqasm.S */
EXPORT_SYMBOL(__get_fiq_regs); /* defined in fiqasm.S */
EXPORT_SYMBOL(claim_fiq);
EXPORT_SYMBOL(release_fiq);
EXPORT_SYMBOL(enable_fiq);
EXPORT_SYMBOL(disable_fiq);
void __init init_FIQ(int start)
{
unsigned offset = FIQ_OFFSET;
no_fiq_insn = *(unsigned long *)(0xffff0000 + offset);
fiq_start = start;
}