// SPDX-License-Identifier: GPL-2.0/* *  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/mach/irq.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,				   (unsigned long)base + 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) {		pr_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;}