linux/arch/arm/include/asm/fiq.h
Dave Martin 2846d84ffa ARM: 6940/1: fiq: Briefly document driver responsibilities for suspend/resume
Drivers which make use of the FIQ interrupt may require the state
of the FIQ mode registers to be preserved across suspend/resume.

Because the FIQ mode registers are not saved and restored
automatically by the kernel, driver authors will need to do the
appropriate save/restore in their own driver suspend/resume
handlers.

Implementing global automatic save/restore of the FIQ state does
not appear appropriate, since this by itself is not sufficient for
FIQ-based drivers to function correctly across suspend/resume in
any case.

This patch adds a brief explanatory note to fiq.h documenting the
requirement placed on driver authors.

Signed-off-by: Dave Martin <dave.martin@linaro.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2011-05-26 10:31:06 +01:00

57 lines
1.3 KiB
C

/*
* arch/arm/include/asm/fiq.h
*
* Support for FIQ on ARM architectures.
* Written by Philip Blundell <philb@gnu.org>, 1998
* Re-written by Russell King
*
* NOTE: The FIQ mode registers are not magically preserved across
* suspend/resume.
*
* Drivers which require these registers to be preserved across power
* management operations must implement appropriate suspend/resume handlers to
* save and restore them.
*/
#ifndef __ASM_FIQ_H
#define __ASM_FIQ_H
#include <asm/ptrace.h>
struct fiq_handler {
struct fiq_handler *next;
/* Name
*/
const char *name;
/* Called to ask driver to relinquish/
* reacquire FIQ
* return zero to accept, or -<errno>
*/
int (*fiq_op)(void *, int relinquish);
/* data for the relinquish/reacquire functions
*/
void *dev_id;
};
extern int claim_fiq(struct fiq_handler *f);
extern void release_fiq(struct fiq_handler *f);
extern void set_fiq_handler(void *start, unsigned int length);
extern void enable_fiq(int fiq);
extern void disable_fiq(int fiq);
/* helpers defined in fiqasm.S: */
extern void __set_fiq_regs(unsigned long const *regs);
extern void __get_fiq_regs(unsigned long *regs);
static inline void set_fiq_regs(struct pt_regs const *regs)
{
__set_fiq_regs(&regs->ARM_r8);
}
static inline void get_fiq_regs(struct pt_regs *regs)
{
__get_fiq_regs(&regs->ARM_r8);
}
#endif