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linux-next/arch/arm/kernel/fiq.c
Daniel Thompson c0e7f7ee71 ARM: 8150/3: fiq: Replace default FIQ handler
This patch introduces a new default FIQ handler that is structured in a
similar way to the existing ARM exception handler and result in the FIQ
being handled by C code running on the SVC stack (despite this code run
in the FIQ handler is subject to severe limitations with respect to
locking making normal interaction with the kernel impossible).

This default handler allows concepts that on x86 would be handled using
NMIs to be realized on ARM.

Credit:

    This patch is a near complete re-write of a patch originally
    provided by Anton Vorontsov. Today only a couple of small fragments
    survive, however without Anton's work to build from this patch would
    not exist. Thanks also to Russell King for spoonfeeding me a variety
    of fixes during the review cycle.

Signed-off-by: Daniel Thompson <daniel.thompson@linaro.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: Nicolas Pitre <nico@linaro.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2014-09-18 00:35:18 +01:00

165 lines
3.6 KiB
C

/*
* 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 dfl_fiq_insn;
static struct pt_regs dfl_fiq_regs;
/* Default reacquire function
* - we always relinquish FIQ control
* - we always reacquire FIQ control
*/
static int fiq_def_op(void *ref, int relinquish)
{
if (!relinquish) {
/* Restore default handler and registers */
local_fiq_disable();
set_fiq_regs(&dfl_fiq_regs);
set_fiq_handler(&dfl_fiq_insn, sizeof(dfl_fiq_insn));
local_fiq_enable();
/* FIXME: notify irq controller to standard enable FIQs */
}
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;
dfl_fiq_insn = *(unsigned long *)(0xffff0000 + offset);
get_fiq_regs(&dfl_fiq_regs);
fiq_start = start;
}