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