| 1 | |
| 2 | |
| 3 | * Copyright (C) 2002 ARM Ltd.
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| 4 | * All Rights Reserved
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| 5 | *
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| 6 | * This hotplug implementation is _specific_ to the situation found on
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| 7 | * ARM development platforms where there is _no_ possibility of actually
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| 8 | * taking a CPU offline, resetting it, or otherwise. Real platforms must
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| 9 | * NOT copy this code.
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| 10 |
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| 11 | #include <linux/kernel.h>
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| 12 | #include <linux/errno.h>
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| 13 | #include <linux/smp.h>
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| 14 |
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| 15 | #include <asm/smp_plat.h>
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| 16 | #include <asm/cp15.h>
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| 17 |
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| 18 | #include "platsmp.h"
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| 19 |
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| 20 | static inline void versatile_immitation_enter_lowpower(unsigned int actrl_mask)
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| 21 | {
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| 22 | unsigned int v;
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| 23 |
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| 24 | asm volatile(
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| 25 | "mcr p15, 0, %1, c7, c5, 0\n"
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| 26 | " mcr p15, 0, %1, c7, c10, 4\n"
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| 27 | |
| 28 | * Turn off coherency
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| 29 |
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| 30 | " mrc p15, 0, %0, c1, c0, 1\n"
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| 31 | " bic %0, %0, %3\n"
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| 32 | " mcr p15, 0, %0, c1, c0, 1\n"
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| 33 | " mrc p15, 0, %0, c1, c0, 0\n"
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| 34 | " bic %0, %0, %2\n"
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| 35 | " mcr p15, 0, %0, c1, c0, 0\n"
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| 36 | : "=&r" (v)
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| 37 | : "r" (0), "Ir" (CR_C), "Ir" (actrl_mask)
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| 38 | : "cc");
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| 39 | }
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| 40 |
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| 41 | static inline void versatile_immitation_leave_lowpower(unsigned int actrl_mask)
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| 42 | {
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| 43 | unsigned int v;
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| 44 |
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| 45 | asm volatile(
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| 46 | "mrc p15, 0, %0, c1, c0, 0\n"
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| 47 | " orr %0, %0, %1\n"
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| 48 | " mcr p15, 0, %0, c1, c0, 0\n"
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| 49 | " mrc p15, 0, %0, c1, c0, 1\n"
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| 50 | " orr %0, %0, %2\n"
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| 51 | " mcr p15, 0, %0, c1, c0, 1\n"
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| 52 | : "=&r" (v)
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| 53 | : "Ir" (CR_C), "Ir" (actrl_mask)
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| 54 | : "cc");
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| 55 | }
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| 56 |
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| 57 | static inline void versatile_immitation_do_lowpower(unsigned int cpu, int *spurious)
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| 58 | {
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| 59 | |
| 60 | * there is no power-control hardware on this platform, so all
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| 61 | * we can do is put the core into WFI; this is safe as the calling
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| 62 | * code will have already disabled interrupts.
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| 63 | *
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| 64 | * This code should not be used outside Versatile platforms.
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| 65 |
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| 66 | for (;;) {
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| 67 | wfi();
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| 68 |
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| 69 | if (versatile_cpu_release == cpu_logical_map(cpu)) {
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| 70 | |
| 71 | * OK, proper wakeup, we're done
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| 72 |
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| 73 | break;
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| 74 | }
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| 75 |
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| 76 | |
| 77 | * Getting here, means that we have come out of WFI without
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| 78 | * having been woken up - this shouldn't happen
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| 79 | *
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| 80 | * Just note it happening - when we're woken, we can report
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| 81 | * its occurrence.
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| 82 |
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| 83 | (*spurious)++;
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| 84 | }
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| 85 | }
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| 86 |
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| 87 | |
| 88 | * platform-specific code to shutdown a CPU.
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| 89 | * This code supports immitation-style CPU hotplug for Versatile/Realview/
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| 90 | * Versatile Express platforms that are unable to do real CPU hotplug.
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| 91 |
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| 92 | void versatile_immitation_cpu_die(unsigned int cpu, unsigned int actrl_mask)
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| 93 | {
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| 94 | int spurious = 0;
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| 95 |
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| 96 | versatile_immitation_enter_lowpower(actrl_mask);
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| 97 | versatile_immitation_do_lowpower(cpu, &spurious);
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| 98 | versatile_immitation_leave_lowpower(actrl_mask);
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| 99 |
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| 100 | if (spurious)
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| 101 | pr_warn("CPU%u: %u spurious wakeup calls\n", cpu, spurious);
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| 102 | }
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