/* * 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/fiq.h> #include <asm/irq.h> #include <asm/system.h> 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, void *v) { if (current_fiq != &default_owner) seq_printf(p, "FIQ: %s\n", current_fiq->name); return 0; } void set_fiq_handler(void *start, unsigned int length) { memcpy((void *)0xffff001c, start, length); flush_icache_range(0xffff001c, 0xffff001c + length); if (!vectors_high()) flush_icache_range(0x1c, 0x1c + length); } /* * Taking an interrupt in FIQ mode is death, so both these functions * disable irqs for the duration. Note - these functions are almost * entirely coded in assembly. */ void __attribute__((naked)) set_fiq_regs(struct pt_regs *regs) { register unsigned long tmp; asm volatile ( "mov ip, sp\n\ stmfd sp!, {fp, ip, lr, pc}\n\ sub fp, ip, #4\n\ mrs %0, cpsr\n\ msr cpsr_c, %2 @ select FIQ mode\n\ mov r0, r0\n\ ldmia %1, {r8 - r14}\n\ msr cpsr_c, %0 @ return to SVC mode\n\ mov r0, r0\n\ ldmfd sp, {fp, sp, pc}" : "=&r" (tmp) : "r" (®s->ARM_r8), "I" (PSR_I_BIT | PSR_F_BIT | FIQ_MODE)); } void __attribute__((naked)) get_fiq_regs(struct pt_regs *regs) { register unsigned long tmp; asm volatile ( "mov ip, sp\n\ stmfd sp!, {fp, ip, lr, pc}\n\ sub fp, ip, #4\n\ mrs %0, cpsr\n\ msr cpsr_c, %2 @ select FIQ mode\n\ mov r0, r0\n\ stmia %1, {r8 - r14}\n\ msr cpsr_c, %0 @ return to SVC mode\n\ mov r0, r0\n\ ldmfd sp, {fp, sp, pc}" : "=&r" (tmp) : "r" (®s->ARM_r8), "I" (PSR_I_BIT | PSR_F_BIT | FIQ_MODE)); } 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)); } 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); EXPORT_SYMBOL(get_fiq_regs); EXPORT_SYMBOL(claim_fiq); EXPORT_SYMBOL(release_fiq); EXPORT_SYMBOL(enable_fiq); EXPORT_SYMBOL(disable_fiq); void __init init_FIQ(void) { no_fiq_insn = *(unsigned long *)0xffff001c; }