diff options
Diffstat (limited to 'arch/arm/kernel/fiq.c')
| -rw-r--r-- | arch/arm/kernel/fiq.c | 181 |
1 files changed, 181 insertions, 0 deletions
diff --git a/arch/arm/kernel/fiq.c b/arch/arm/kernel/fiq.c new file mode 100644 index 000000000000..9299dfc25698 --- /dev/null +++ b/arch/arm/kernel/fiq.c @@ -0,0 +1,181 @@ +/* + * 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/seq_file.h> + +#include <asm/cacheflush.h> +#include <asm/fiq.h> +#include <asm/irq.h> +#include <asm/system.h> +#include <asm/uaccess.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\ + ldmea fp, {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\ + ldmea fp, {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; +} |