// SPDX-License-Identifier: GPL-2.0-only/* *  Copyright (C) 2002 ARM Ltd. *  All Rights Reserved * * This hotplug implementation is _specific_ to the situation found on * ARM development platforms where there is _no_ possibility of actually * taking a CPU offline, resetting it, or otherwise.  Real platforms must * NOT copy this code. */#include <linux/kernel.h>#include <linux/errno.h>#include <linux/smp.h> #include <asm/smp_plat.h>#include <asm/cp15.h> #include "platsmp.h" static inline void versatile_immitation_enter_lowpower(unsigned int actrl_mask){	unsigned int v; 	asm volatile(		"mcr	p15, 0, %1, c7, c5, 0\n"	"	mcr	p15, 0, %1, c7, c10, 4\n"	/*	 * Turn off coherency	 */	"	mrc	p15, 0, %0, c1, c0, 1\n"	"	bic	%0, %0, %3\n"	"	mcr	p15, 0, %0, c1, c0, 1\n"	"	mrc	p15, 0, %0, c1, c0, 0\n"	"	bic	%0, %0, %2\n"	"	mcr	p15, 0, %0, c1, c0, 0\n"	  : "=&r" (v)	  : "r" (0), "Ir" (CR_C), "Ir" (actrl_mask)	  : "cc");} static inline void versatile_immitation_leave_lowpower(unsigned int actrl_mask){	unsigned int v; 	asm volatile(		"mrc	p15, 0, %0, c1, c0, 0\n"	"	orr	%0, %0, %1\n"	"	mcr	p15, 0, %0, c1, c0, 0\n"	"	mrc	p15, 0, %0, c1, c0, 1\n"	"	orr	%0, %0, %2\n"	"	mcr	p15, 0, %0, c1, c0, 1\n"	  : "=&r" (v)	  : "Ir" (CR_C), "Ir" (actrl_mask)	  : "cc");} static inline void versatile_immitation_do_lowpower(unsigned int cpu, int *spurious){	/*	 * there is no power-control hardware on this platform, so all	 * we can do is put the core into WFI; this is safe as the calling	 * code will have already disabled interrupts.	 *	 * This code should not be used outside Versatile platforms.	 */	for (;;) {		wfi(); 		if (versatile_cpu_release == cpu_logical_map(cpu)) {			/*			 * OK, proper wakeup, we're done			 */			break;		} 		/*		 * Getting here, means that we have come out of WFI without		 * having been woken up - this shouldn't happen		 *		 * Just note it happening - when we're woken, we can report		 * its occurrence.		 */		(*spurious)++;	}} /* * platform-specific code to shutdown a CPU. * This code supports immitation-style CPU hotplug for Versatile/Realview/ * Versatile Express platforms that are unable to do real CPU hotplug. */void versatile_immitation_cpu_die(unsigned int cpu, unsigned int actrl_mask){	int spurious = 0; 	versatile_immitation_enter_lowpower(actrl_mask);	versatile_immitation_do_lowpower(cpu, &spurious);	versatile_immitation_leave_lowpower(actrl_mask); 	if (spurious)		pr_warn("CPU%u: %u spurious wakeup calls\n", cpu, spurious);}