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