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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/config.h>
#include <linux/mm.h>
#include <linux/mman.h>
#include <linux/init.h>
#include <asm/fiq.h>
#include <asm/io.h>
#include <asm/pgtable.h>
#include <asm/system.h>
#include <asm/uaccess.h>
#define FIQ_VECTOR 0x1c
static unsigned long no_fiq_insn;
#ifdef CONFIG_CPU_32
static inline void unprotect_page_0(void)
{
modify_domain(DOMAIN_USER, DOMAIN_MANAGER);
}
static inline void protect_page_0(void)
{
modify_domain(DOMAIN_USER, DOMAIN_CLIENT);
}
#else
#define unprotect_page_0()
#define protect_page_0()
#endif
/* Default reacquire function
* - we always relinquish FIQ control
* - we always reacquire FIQ control
*/
int fiq_def_op(void *ref, int relinquish)
{
if (!relinquish) {
unprotect_page_0();
*(unsigned long *)FIQ_VECTOR = no_fiq_insn;
protect_page_0();
flush_icache_range(FIQ_VECTOR, FIQ_VECTOR + 4);
}
return 0;
}
static struct fiq_handler default_owner =
{ NULL, "default", fiq_def_op, NULL };
static struct fiq_handler *current_fiq = &default_owner;
int get_fiq_list(char *buf)
{
char *p = buf;
if (current_fiq != &default_owner)
p += sprintf(p, "FIQ: %s\n",
current_fiq->name);
return p - buf;
}
void set_fiq_handler(void *start, unsigned int length)
{
unprotect_page_0();
memcpy((void *)FIQ_VECTOR, start, length);
protect_page_0();
flush_icache_range(FIQ_VECTOR, FIQ_VECTOR + length);
}
/*
* Taking an interrupt in FIQ mode is death, so both these functions
* disable irqs for the duration.
*/
void set_fiq_regs(struct pt_regs *regs)
{
register unsigned long tmp, tmp2;
__asm__ volatile (
#ifdef CONFIG_CPU_26
"mov %0, pc
bic %1, %0, #0x3
orr %1, %1, #0x0c000001
teqp %1, #0 @ select FIQ mode
mov r0, r0
ldmia %2, {r8 - r14}
teqp %0, #0 @ return to SVC mode
mov r0, r0"
#endif
#ifdef CONFIG_CPU_32
"mrs %0, cpsr
bic %1, %0, #0xf
orr %1, %1, #0xc1
msr cpsr, %1 @ select FIQ mode
mov r0, r0
ldmia %2, {r8 - r14}
msr cpsr, %0 @ return to SVC mode
mov r0, r0"
#endif
: "=r" (tmp), "=r" (tmp2)
: "r" (®s->ARM_r8)
/* These registers aren't modified by the above code in a way
visible to the compiler, but we mark them as clobbers anyway
so that GCC won't put any of the input or output operands in
them. */
: "r8", "r9", "r10", "r11", "r12", "r13", "r14");
}
void get_fiq_regs(struct pt_regs *regs)
{
register unsigned long tmp, tmp2;
__asm__ volatile (
#ifdef CONFIG_CPU_26
"mov %0, pc
bic %1, %0, #0x3
orr %1, %1, #0x0c000001
teqp %1, #0 @ select FIQ mode
mov r0, r0
stmia %2, {r8 - r14}
teqp %0, #0 @ return to SVC mode
mov r0, r0"
#endif
#ifdef CONFIG_CPU_32
"mrs %0, cpsr
bic %1, %0, #0xf
orr %1, %1, #0xc1
msr cpsr, %1 @ select FIQ mode
mov r0, r0
stmia %2, {r8 - r14}
msr cpsr, %0 @ return to SVC mode
mov r0, r0"
#endif
: "=r" (tmp), "=r" (tmp2)
: "r" (®s->ARM_r8)
/* These registers aren't modified by the above code in a way
visible to the compiler, but we mark them as clobbers anyway
so that GCC won't put any of the input or output operands in
them. */
: "r8", "r9", "r10", "r11", "r12", "r13", "r14");
}
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);
#ifdef CONFIG_DEBUG_ERRORS
__backtrace();
#endif
return;
}
do
current_fiq = current_fiq->next;
while (current_fiq->fiq_op(current_fiq->dev_id, 0));
}
void __init init_FIQ(void)
{
no_fiq_insn = *(unsigned long *)FIQ_VECTOR;
set_fs(get_fs());
}
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