// SPDX-License-Identifier: GPL-2.0/* *	Precise Delay Loops for parisc * *	based on code by: *	Copyright (C) 1993 Linus Torvalds *	Copyright (C) 1997 Martin Mares <mj@atrey.karlin.mff.cuni.cz> *	Copyright (C) 2008 Jiri Hladky <hladky _dot_ jiri _at_ gmail _dot_ com> * *	parisc implementation: *	Copyright (C) 2013 Helge Deller <deller@gmx.de> */  #include <linux/module.h>#include <linux/preempt.h>#include <linux/init.h> #include <asm/delay.h>#include <asm/special_insns.h>    /* for mfctl() */#include <asm/processor.h> /* for boot_cpu_data */ /* CR16 based delay: */static void __cr16_delay(unsigned long __loops){	/*	 * Note: Due to unsigned math, cr16 rollovers shouldn't be	 * a problem here. However, on 32 bit, we need to make sure	 * we don't pass in too big a value. The current default	 * value of MAX_UDELAY_MS should help prevent this.	 */	u32 bclock, now, loops = __loops;	int cpu; 	preempt_disable();	cpu = smp_processor_id();	bclock = mfctl(16);	for (;;) {		now = mfctl(16);		if ((now - bclock) >= loops)			break; 		/* Allow RT tasks to run */		preempt_enable();		asm volatile("	nop\n");		barrier();		preempt_disable(); 		/*		 * It is possible that we moved to another CPU, and		 * since CR16's are per-cpu we need to calculate		 * that. The delay must guarantee that we wait "at		 * least" the amount of time. Being moved to another		 * CPU could make the wait longer but we just need to		 * make sure we waited long enough. Rebalance the		 * counter for this CPU.		 */		if (unlikely(cpu != smp_processor_id())) {			loops -= (now - bclock);			cpu = smp_processor_id();			bclock = mfctl(16);		}	}	preempt_enable();}  void __udelay(unsigned long usecs){	__cr16_delay(usecs * ((unsigned long)boot_cpu_data.cpu_hz / 1000000UL));}EXPORT_SYMBOL(__udelay);