diff options
Diffstat (limited to 'arch/arm26/kernel/fiq.c')
| -rw-r--r-- | arch/arm26/kernel/fiq.c | 202 |
1 files changed, 202 insertions, 0 deletions
diff --git a/arch/arm26/kernel/fiq.c b/arch/arm26/kernel/fiq.c new file mode 100644 index 000000000000..08a97c9498ff --- /dev/null +++ b/arch/arm26/kernel/fiq.c @@ -0,0 +1,202 @@ +/* + * linux/arch/arm26/kernel/fiq.c + * + * Copyright (C) 1998 Russell King + * Copyright (C) 1998, 1999 Phil Blundell + * Copyright (C) 2003 Ian Molton + * + * 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/module.h> +#include <linux/mm.h> +#include <linux/mman.h> +#include <linux/init.h> +#include <linux/seq_file.h> + +#include <asm/fiq.h> +#include <asm/io.h> +#include <asm/irq.h> +#include <asm/pgalloc.h> +#include <asm/system.h> +#include <asm/uaccess.h> + +#define FIQ_VECTOR (vectors_base() + 0x1c) + +static unsigned long no_fiq_insn; + +#define unprotect_page_0() +#define protect_page_0() + +/* Default reacquire function + * - we always relinquish FIQ control + * - we always reacquire FIQ control + */ +static int fiq_def_op(void *ref, int relinquish) +{ + if (!relinquish) { + unprotect_page_0(); + *(unsigned long *)FIQ_VECTOR = no_fiq_insn; + protect_page_0(); + } + + 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) +{ + unprotect_page_0(); + + memcpy((void *)FIQ_VECTOR, start, length); + + protect_page_0(); +} + +/* + * 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 ( + "mov %0, pc + bic %1, %0, #0x3 + orr %1, %1, %3 + teqp %1, #0 @ select FIQ mode + mov r0, r0 + ldmia %2, {r8 - r14} + teqp %0, #0 @ return to SVC mode + mov r0, r0" + : "=&r" (tmp), "=&r" (tmp2) + : "r" (®s->ARM_r8), "I" (PSR_I_BIT | PSR_F_BIT | MODE_FIQ26) + /* 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 ( + "mov %0, pc + bic %1, %0, #0x3 + orr %1, %1, %3 + teqp %1, #0 @ select FIQ mode + mov r0, r0 + stmia %2, {r8 - r14} + teqp %0, #0 @ return to SVC mode + mov r0, r0" + : "=&r" (tmp), "=&r" (tmp2) + : "r" (®s->ARM_r8), "I" (PSR_I_BIT | PSR_F_BIT | MODE_FIQ26) + /* 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 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 *)FIQ_VECTOR; + set_fs(get_fs()); +} |