FM / asm

/usr/src/linux-headers-5.15.0-190/arch/arc/include/asm/

/usr/src/linux-headers-5.15.0-190/arch/arc/include/asm

Name	Size	Mode	Actions
arcregs.h	9477	0644	edit dl rm
asm-offsets.h	165	0644	edit dl rm
asserts.h	958	0644	edit dl rm
atomic-llsc.h	2864	0644	edit dl rm
atomic-spinlock.h	2569	0644	edit dl rm
atomic.h	1153	0644	edit dl rm
atomic64-arcv2.h	6095	0644	edit dl rm
barrier.h	1376	0644	edit dl rm
bitops.h	3885	0644	edit dl rm
bug.h	819	0644	edit dl rm
cache.h	3604	0644	edit dl rm
cacheflush.h	3824	0644	edit dl rm
checksum.h	2371	0644	edit dl rm
cmpxchg.h	3188	0644	edit dl rm
current.h	549	0644	edit dl rm
delay.h	1896	0644	edit dl rm
disasm.h	3813	0644	edit dl rm
dma.h	313	0644	edit dl rm
dsp-impl.h	3860	0644	edit dl rm
dsp.h	796	0644	edit dl rm
dwarf.h	746	0644	edit dl rm
elf.h	1935	0644	edit dl rm
entry-arcv2.h	7419	0644	edit dl rm
entry-compact.h	8810	0644	edit dl rm
entry.h	6687	0644	edit dl rm
exec.h	264	0644	edit dl rm
fb.h	411	0644	edit dl rm
fpu.h	1125	0644	edit dl rm
futex.h	3611	0644	edit dl rm
highmem.h	1422	0644	edit dl rm
hugepage.h	2071	0644	edit dl rm
io.h	6291	0644	edit dl rm
irq.h	679	0644	edit dl rm
irqflags-arcv2.h	3491	0644	edit dl rm
irqflags-compact.h	4293	0644	edit dl rm
irqflags.h	363	0644	edit dl rm
jump_label.h	1976	0644	edit dl rm
Kbuild	153	0644	edit dl rm
kdebug.h	254	0644	edit dl rm
kgdb.h	1239	0644	edit dl rm
kprobes.h	1186	0644	edit dl rm
linkage.h	1484	0644	edit dl rm
mach_desc.h	1943	0644	edit dl rm
mmu-arcv2.h	2494	0644	edit dl rm
mmu.h	387	0644	edit dl rm
mmu_context.h	5568	0644	edit dl rm
module.h	428	0644	edit dl rm
page.h	3313	0644	edit dl rm
pci.h	360	0644	edit dl rm
perf_event.h	6879	0644	edit dl rm
pgalloc.h	2888	0644	edit dl rm
pgtable-bits-arcv2.h	4896	0644	edit dl rm
pgtable-levels.h	5626	0644	edit dl rm
pgtable.h	780	0644	edit dl rm
processor.h	3253	0644	edit dl rm
ptrace.h	3759	0644	edit dl rm
sections.h	261	0644	edit dl rm
segment.h	476	0644	edit dl rm
serial.h	498	0644	edit dl rm
setup.h	1274	0644	edit dl rm
shmparam.h	296	0644	edit dl rm
smp.h	3823	0644	edit dl rm
spinlock.h	8580	0644	edit dl rm
spinlock_types.h	905	0644	edit dl rm
stacktrace.h	1178	0644	edit dl rm
string.h	1036	0644	edit dl rm
switch_to.h	553	0644	edit dl rm
syscall.h	1738	0644	edit dl rm
syscalls.h	547	0644	edit dl rm
thread_info.h	3339	0644	edit dl rm
timex.h	362	0644	edit dl rm
tlb.h	262	0644	edit dl rm
tlbflush.h	1654	0644	edit dl rm
uaccess.h	17019	0644	edit dl rm
unaligned.h	625	0644	edit dl rm
unwind.h	3446	0644	edit dl rm
vermagic.h	157	0644	edit dl rm
vmalloc.h	87	0644	edit dl rm

Edit: /usr/src/linux-headers-5.15.0-190/arch/arc/include/asm/delay.h (1896B)

/* SPDX-License-Identifier: GPL-2.0-only */
/*
 * Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com)
 *
 * Delay routines using pre computed loops_per_jiffy value.
 *
 * vineetg: Feb 2012
 *  -Rewrote in "C" to avoid dealing with availability of H/w MPY
 *  -Also reduced the num of MPY operations from 3 to 2
 *
 * Amit Bhor: Codito Technologies 2004
 */

#ifndef __ASM_ARC_UDELAY_H
#define __ASM_ARC_UDELAY_H

#include <asm-generic/types.h>
#include <asm/param.h>		/* HZ */

extern unsigned long loops_per_jiffy;

static inline void __delay(unsigned long loops)
{
	__asm__ __volatile__(
	"	mov lp_count, %0	\n"
	"	lp  1f			\n"
	"	nop			\n"
	"1:				\n"
	:
        : "r"(loops)
        : "lp_count");
}

extern void __bad_udelay(void);

/*
 * Normal Math for computing loops in "N" usecs
 *  -we have precomputed @loops_per_jiffy
 *  -1 sec has HZ jiffies
 * loops per "N" usecs = ((loops_per_jiffy * HZ / 1000000) * N)
 *
 * Approximate Division by multiplication:
 *  -Mathematically if we multiply and divide a number by same value the
 *   result remains unchanged:  In this case, we use 2^32
 *  -> (loops_per_N_usec * 2^32 ) / 2^32
 *  -> (((loops_per_jiffy * HZ / 1000000) * N) * 2^32) / 2^32
 *  -> (loops_per_jiffy * HZ * N * 4295) / 2^32
 *
 *  -Divide by 2^32 is very simply right shift by 32
 *  -We simply need to ensure that the multiply per above eqn happens in
 *   64-bit precision (if CPU doesn't support it - gcc can emaulate it)
 */

static inline void __udelay(unsigned long usecs)
{
	unsigned long loops;

/* (u64) cast ensures 64 bit MPY - real or emulated
	 * HZ * 4295 is pre-evaluated by gcc - hence only 2 mpy ops
	 */
	loops = ((u64) usecs * 4295 * HZ * loops_per_jiffy) >> 32;

__delay(loops);
}

#define udelay(n) (__builtin_constant_p(n) ? ((n) > 20000 ? __bad_udelay() \
				: __udelay(n)) : __udelay(n))

#endif /* __ASM_ARC_UDELAY_H */

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