| Kyle Swenson | 8d8f654 | 2021-03-15 11:02:55 -0600 | [diff] [blame^] | 1 | /* |
| 2 | * linux/arch/arm/mach-spear13xx/hotplug.c |
| 3 | * |
| 4 | * Copyright (C) 2012 ST Microelectronics Ltd. |
| 5 | * Deepak Sikri <deepak.sikri@st.com> |
| 6 | * |
| 7 | * based upon linux/arch/arm/mach-realview/hotplug.c |
| 8 | * |
| 9 | * This program is free software; you can redistribute it and/or modify |
| 10 | * it under the terms of the GNU General Public License version 2 as |
| 11 | * published by the Free Software Foundation. |
| 12 | */ |
| 13 | #include <linux/kernel.h> |
| 14 | #include <linux/errno.h> |
| 15 | #include <linux/smp.h> |
| 16 | #include <asm/cp15.h> |
| 17 | #include <asm/smp_plat.h> |
| 18 | |
| 19 | static inline void cpu_enter_lowpower(void) |
| 20 | { |
| 21 | unsigned int v; |
| 22 | |
| 23 | asm volatile( |
| 24 | " mcr p15, 0, %1, c7, c5, 0\n" |
| 25 | " dsb\n" |
| 26 | /* |
| 27 | * Turn off coherency |
| 28 | */ |
| 29 | " mrc p15, 0, %0, c1, c0, 1\n" |
| 30 | " bic %0, %0, #0x20\n" |
| 31 | " mcr p15, 0, %0, c1, c0, 1\n" |
| 32 | " mrc p15, 0, %0, c1, c0, 0\n" |
| 33 | " bic %0, %0, %2\n" |
| 34 | " mcr p15, 0, %0, c1, c0, 0\n" |
| 35 | : "=&r" (v) |
| 36 | : "r" (0), "Ir" (CR_C) |
| 37 | : "cc", "memory"); |
| 38 | } |
| 39 | |
| 40 | static inline void cpu_leave_lowpower(void) |
| 41 | { |
| 42 | unsigned int v; |
| 43 | |
| 44 | asm volatile("mrc p15, 0, %0, c1, c0, 0\n" |
| 45 | " orr %0, %0, %1\n" |
| 46 | " mcr p15, 0, %0, c1, c0, 0\n" |
| 47 | " mrc p15, 0, %0, c1, c0, 1\n" |
| 48 | " orr %0, %0, #0x20\n" |
| 49 | " mcr p15, 0, %0, c1, c0, 1\n" |
| 50 | : "=&r" (v) |
| 51 | : "Ir" (CR_C) |
| 52 | : "cc"); |
| 53 | } |
| 54 | |
| 55 | static inline void spear13xx_do_lowpower(unsigned int cpu, int *spurious) |
| 56 | { |
| 57 | for (;;) { |
| 58 | wfi(); |
| 59 | |
| 60 | if (pen_release == cpu) { |
| 61 | /* |
| 62 | * OK, proper wakeup, we're done |
| 63 | */ |
| 64 | break; |
| 65 | } |
| 66 | |
| 67 | /* |
| 68 | * Getting here, means that we have come out of WFI without |
| 69 | * having been woken up - this shouldn't happen |
| 70 | * |
| 71 | * Just note it happening - when we're woken, we can report |
| 72 | * its occurrence. |
| 73 | */ |
| 74 | (*spurious)++; |
| 75 | } |
| 76 | } |
| 77 | |
| 78 | /* |
| 79 | * platform-specific code to shutdown a CPU |
| 80 | * |
| 81 | * Called with IRQs disabled |
| 82 | */ |
| 83 | void spear13xx_cpu_die(unsigned int cpu) |
| 84 | { |
| 85 | int spurious = 0; |
| 86 | |
| 87 | /* |
| 88 | * we're ready for shutdown now, so do it |
| 89 | */ |
| 90 | cpu_enter_lowpower(); |
| 91 | spear13xx_do_lowpower(cpu, &spurious); |
| 92 | |
| 93 | /* |
| 94 | * bring this CPU back into the world of cache |
| 95 | * coherency, and then restore interrupts |
| 96 | */ |
| 97 | cpu_leave_lowpower(); |
| 98 | |
| 99 | if (spurious) |
| 100 | pr_warn("CPU%u: %u spurious wakeup calls\n", cpu, spurious); |
| 101 | } |