183 lines
4.0 KiB
C
183 lines
4.0 KiB
C
/*
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* linux/arch/arm/kernel/fiq.c
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*
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* Copyright (C) 1998 Russell King
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* Copyright (C) 1998, 1999 Phil Blundell
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*
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* FIQ support written by Philip Blundell <philb@gnu.org>, 1998.
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*
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* FIQ support re-written by Russell King to be more generic
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*
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* We now properly support a method by which the FIQ handlers can
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* be stacked onto the vector. We still do not support sharing
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* the FIQ vector itself.
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*
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* Operation is as follows:
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* 1. Owner A claims FIQ:
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* - default_fiq relinquishes control.
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* 2. Owner A:
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* - inserts code.
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* - sets any registers,
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* - enables FIQ.
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* 3. Owner B claims FIQ:
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* - if owner A has a relinquish function.
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* - disable FIQs.
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* - saves any registers.
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* - returns zero.
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* 4. Owner B:
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* - inserts code.
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* - sets any registers,
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* - enables FIQ.
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* 5. Owner B releases FIQ:
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* - Owner A is asked to reacquire FIQ:
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* - inserts code.
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* - restores saved registers.
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* - enables FIQ.
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* 6. Goto 3
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*/
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#include <linux/module.h>
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#include <linux/kernel.h>
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#include <linux/init.h>
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#include <linux/interrupt.h>
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#include <linux/seq_file.h>
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#include <asm/cacheflush.h>
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#include <asm/fiq.h>
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#include <asm/irq.h>
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#include <asm/system.h>
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#include <asm/uaccess.h>
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static unsigned long no_fiq_insn;
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/* Default reacquire function
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* - we always relinquish FIQ control
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* - we always reacquire FIQ control
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*/
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static int fiq_def_op(void *ref, int relinquish)
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{
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if (!relinquish)
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set_fiq_handler(&no_fiq_insn, sizeof(no_fiq_insn));
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return 0;
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}
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static struct fiq_handler default_owner = {
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.name = "default",
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.fiq_op = fiq_def_op,
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};
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static struct fiq_handler *current_fiq = &default_owner;
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int show_fiq_list(struct seq_file *p, void *v)
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{
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if (current_fiq != &default_owner)
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seq_printf(p, "FIQ: %s\n", current_fiq->name);
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return 0;
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}
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void set_fiq_handler(void *start, unsigned int length)
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{
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memcpy((void *)0xffff001c, start, length);
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flush_icache_range(0xffff001c, 0xffff001c + length);
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if (!vectors_high())
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flush_icache_range(0x1c, 0x1c + length);
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}
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/*
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* Taking an interrupt in FIQ mode is death, so both these functions
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* disable irqs for the duration. Note - these functions are almost
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* entirely coded in assembly.
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*/
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void __attribute__((naked)) set_fiq_regs(struct pt_regs *regs)
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{
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register unsigned long tmp;
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asm volatile (
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"mov ip, sp\n\
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stmfd sp!, {fp, ip, lr, pc}\n\
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sub fp, ip, #4\n\
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mrs %0, cpsr\n\
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msr cpsr_c, %2 @ select FIQ mode\n\
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mov r0, r0\n\
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ldmia %1, {r8 - r14}\n\
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msr cpsr_c, %0 @ return to SVC mode\n\
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mov r0, r0\n\
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ldmfd sp, {fp, sp, pc}"
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: "=&r" (tmp)
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: "r" (®s->ARM_r8), "I" (PSR_I_BIT | PSR_F_BIT | FIQ_MODE));
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}
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void __attribute__((naked)) get_fiq_regs(struct pt_regs *regs)
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{
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register unsigned long tmp;
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asm volatile (
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"mov ip, sp\n\
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stmfd sp!, {fp, ip, lr, pc}\n\
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sub fp, ip, #4\n\
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mrs %0, cpsr\n\
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msr cpsr_c, %2 @ select FIQ mode\n\
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mov r0, r0\n\
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stmia %1, {r8 - r14}\n\
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msr cpsr_c, %0 @ return to SVC mode\n\
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mov r0, r0\n\
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ldmfd sp, {fp, sp, pc}"
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: "=&r" (tmp)
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: "r" (®s->ARM_r8), "I" (PSR_I_BIT | PSR_F_BIT | FIQ_MODE));
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}
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int claim_fiq(struct fiq_handler *f)
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{
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int ret = 0;
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if (current_fiq) {
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ret = -EBUSY;
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if (current_fiq->fiq_op != NULL)
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ret = current_fiq->fiq_op(current_fiq->dev_id, 1);
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}
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if (!ret) {
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f->next = current_fiq;
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current_fiq = f;
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}
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return ret;
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}
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void release_fiq(struct fiq_handler *f)
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{
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if (current_fiq != f) {
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printk(KERN_ERR "%s FIQ trying to release %s FIQ\n",
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f->name, current_fiq->name);
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dump_stack();
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return;
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}
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do
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current_fiq = current_fiq->next;
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while (current_fiq->fiq_op(current_fiq->dev_id, 0));
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}
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void enable_fiq(int fiq)
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{
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enable_irq(fiq + FIQ_START);
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}
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void disable_fiq(int fiq)
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{
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disable_irq(fiq + FIQ_START);
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}
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EXPORT_SYMBOL(set_fiq_handler);
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EXPORT_SYMBOL(set_fiq_regs);
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EXPORT_SYMBOL(get_fiq_regs);
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EXPORT_SYMBOL(claim_fiq);
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EXPORT_SYMBOL(release_fiq);
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EXPORT_SYMBOL(enable_fiq);
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EXPORT_SYMBOL(disable_fiq);
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void __init init_FIQ(void)
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{
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no_fiq_insn = *(unsigned long *)0xffff001c;
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}
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