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Diffstat (limited to 'arch/arm/kernel/fiq.c')
| -rw-r--r-- | arch/arm/kernel/fiq.c | 165 |
1 files changed, 165 insertions, 0 deletions
diff --git a/arch/arm/kernel/fiq.c b/arch/arm/kernel/fiq.c new file mode 100644 index 000000000..98ca3e3fa --- /dev/null +++ b/arch/arm/kernel/fiq.c @@ -0,0 +1,165 @@ +// 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/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; +} |