/* * linux/arch/arm/mach-spear13xx/hotplug.c * * Copyright (C) 2012 ST Microelectronics Ltd. * Deepak Sikri <deepak.sikri@st.com> * * based upon linux/arch/arm/mach-realview/hotplug.c * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License version 2 as * published by the Free Software Foundation. */ #include <linux/kernel.h> #include <linux/errno.h> #include <linux/smp.h> #include <asm/cp15.h> #include <asm/smp_plat.h> static inline void cpu_enter_lowpower(void) { unsigned int v; asm volatile( " mcr p15, 0, %1, c7, c5, 0\n" " dsb\n" /* * Turn off coherency */ " mrc p15, 0, %0, c1, c0, 1\n" " bic %0, %0, #0x20\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) : "cc", "memory"); } static inline void cpu_leave_lowpower(void) { 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, #0x20\n" " mcr p15, 0, %0, c1, c0, 1\n" : "=&r" (v) : "Ir" (CR_C) : "cc"); } static inline void spear13xx_do_lowpower(unsigned int cpu, int *spurious) { for (;;) { wfi(); if (pen_release == 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 * * Called with IRQs disabled */ void spear13xx_cpu_die(unsigned int cpu) { int spurious = 0; /* * we're ready for shutdown now, so do it */ cpu_enter_lowpower(); spear13xx_do_lowpower(cpu, &spurious); /* * bring this CPU back into the world of cache * coherency, and then restore interrupts */ cpu_leave_lowpower(); if (spurious) pr_warn("CPU%u: %u spurious wakeup calls\n", cpu, spurious); }