1/* 2 * arch/arm/common/mcpm_head.S -- kernel entry point for multi-cluster PM 3 * 4 * Created by: Nicolas Pitre, March 2012 5 * Copyright: (C) 2012-2013 Linaro Limited 6 * 7 * This program is free software; you can redistribute it and/or modify 8 * it under the terms of the GNU General Public License version 2 as 9 * published by the Free Software Foundation. 10 * 11 * 12 * Refer to Documentation/arm/cluster-pm-race-avoidance.txt 13 * for details of the synchronisation algorithms used here. 14 */ 15 16#include <linux/linkage.h> 17#include <asm/mcpm.h> 18#include <asm/assembler.h> 19 20#include "vlock.h" 21 22.if MCPM_SYNC_CLUSTER_CPUS 23.error "cpus must be the first member of struct mcpm_sync_struct" 24.endif 25 26 .macro pr_dbg string 27#if defined(CONFIG_DEBUG_LL) && defined(DEBUG) 28 b 1901f 291902: .asciz "CPU" 301903: .asciz " cluster" 311904: .asciz ": \string" 32 .align 331901: adr r0, 1902b 34 bl printascii 35 mov r0, r9 36 bl printhex2 37 adr r0, 1903b 38 bl printascii 39 mov r0, r10 40 bl printhex2 41 adr r0, 1904b 42 bl printascii 43#endif 44 .endm 45 46 .arm 47 .align 48 49ENTRY(mcpm_entry_point) 50 51 ARM_BE8(setend be) 52 THUMB( adr r12, BSYM(1f) ) 53 THUMB( bx r12 ) 54 THUMB( .thumb ) 551: 56 mrc p15, 0, r0, c0, c0, 5 @ MPIDR 57 ubfx r9, r0, #0, #8 @ r9 = cpu 58 ubfx r10, r0, #8, #8 @ r10 = cluster 59 mov r3, #MAX_CPUS_PER_CLUSTER 60 mla r4, r3, r10, r9 @ r4 = canonical CPU index 61 cmp r4, #(MAX_CPUS_PER_CLUSTER * MAX_NR_CLUSTERS) 62 blo 2f 63 64 /* We didn't expect this CPU. Try to cheaply make it quiet. */ 651: wfi 66 wfe 67 b 1b 68 692: pr_dbg "kernel mcpm_entry_point\n" 70 71 /* 72 * MMU is off so we need to get to various variables in a 73 * position independent way. 74 */ 75 adr r5, 3f 76 ldmia r5, {r0, r6, r7, r8, r11} 77 add r0, r5, r0 @ r0 = mcpm_entry_early_pokes 78 add r6, r5, r6 @ r6 = mcpm_entry_vectors 79 ldr r7, [r5, r7] @ r7 = mcpm_power_up_setup_phys 80 add r8, r5, r8 @ r8 = mcpm_sync 81 add r11, r5, r11 @ r11 = first_man_locks 82 83 @ Perform an early poke, if any 84 add r0, r0, r4, lsl #3 85 ldmia r0, {r0, r1} 86 teq r0, #0 87 strne r1, [r0] 88 89 mov r0, #MCPM_SYNC_CLUSTER_SIZE 90 mla r8, r0, r10, r8 @ r8 = sync cluster base 91 92 @ Signal that this CPU is coming UP: 93 mov r0, #CPU_COMING_UP 94 mov r5, #MCPM_SYNC_CPU_SIZE 95 mla r5, r9, r5, r8 @ r5 = sync cpu address 96 strb r0, [r5] 97 98 @ At this point, the cluster cannot unexpectedly enter the GOING_DOWN 99 @ state, because there is at least one active CPU (this CPU). 100 101 mov r0, #VLOCK_SIZE 102 mla r11, r0, r10, r11 @ r11 = cluster first man lock 103 mov r0, r11 104 mov r1, r9 @ cpu 105 bl vlock_trylock @ implies DMB 106 107 cmp r0, #0 @ failed to get the lock? 108 bne mcpm_setup_wait @ wait for cluster setup if so 109 110 ldrb r0, [r8, #MCPM_SYNC_CLUSTER_CLUSTER] 111 cmp r0, #CLUSTER_UP @ cluster already up? 112 bne mcpm_setup @ if not, set up the cluster 113 114 @ Otherwise, release the first man lock and skip setup: 115 mov r0, r11 116 bl vlock_unlock 117 b mcpm_setup_complete 118 119mcpm_setup: 120 @ Control dependency implies strb not observable before previous ldrb. 121 122 @ Signal that the cluster is being brought up: 123 mov r0, #INBOUND_COMING_UP 124 strb r0, [r8, #MCPM_SYNC_CLUSTER_INBOUND] 125 dmb 126 127 @ Any CPU trying to take the cluster into CLUSTER_GOING_DOWN from this 128 @ point onwards will observe INBOUND_COMING_UP and abort. 129 130 @ Wait for any previously-pending cluster teardown operations to abort 131 @ or complete: 132mcpm_teardown_wait: 133 ldrb r0, [r8, #MCPM_SYNC_CLUSTER_CLUSTER] 134 cmp r0, #CLUSTER_GOING_DOWN 135 bne first_man_setup 136 wfe 137 b mcpm_teardown_wait 138 139first_man_setup: 140 dmb 141 142 @ If the outbound gave up before teardown started, skip cluster setup: 143 144 cmp r0, #CLUSTER_UP 145 beq mcpm_setup_leave 146 147 @ power_up_setup is now responsible for setting up the cluster: 148 149 cmp r7, #0 150 mov r0, #1 @ second (cluster) affinity level 151 blxne r7 @ Call power_up_setup if defined 152 dmb 153 154 mov r0, #CLUSTER_UP 155 strb r0, [r8, #MCPM_SYNC_CLUSTER_CLUSTER] 156 dmb 157 158mcpm_setup_leave: 159 @ Leave the cluster setup critical section: 160 161 mov r0, #INBOUND_NOT_COMING_UP 162 strb r0, [r8, #MCPM_SYNC_CLUSTER_INBOUND] 163 dsb st 164 sev 165 166 mov r0, r11 167 bl vlock_unlock @ implies DMB 168 b mcpm_setup_complete 169 170 @ In the contended case, non-first men wait here for cluster setup 171 @ to complete: 172mcpm_setup_wait: 173 ldrb r0, [r8, #MCPM_SYNC_CLUSTER_CLUSTER] 174 cmp r0, #CLUSTER_UP 175 wfene 176 bne mcpm_setup_wait 177 dmb 178 179mcpm_setup_complete: 180 @ If a platform-specific CPU setup hook is needed, it is 181 @ called from here. 182 183 cmp r7, #0 184 mov r0, #0 @ first (CPU) affinity level 185 blxne r7 @ Call power_up_setup if defined 186 dmb 187 188 @ Mark the CPU as up: 189 190 mov r0, #CPU_UP 191 strb r0, [r5] 192 193 @ Observability order of CPU_UP and opening of the gate does not matter. 194 195mcpm_entry_gated: 196 ldr r5, [r6, r4, lsl #2] @ r5 = CPU entry vector 197 cmp r5, #0 198 wfeeq 199 beq mcpm_entry_gated 200 dmb 201 202 pr_dbg "released\n" 203 bx r5 204 205 .align 2 206 2073: .word mcpm_entry_early_pokes - . 208 .word mcpm_entry_vectors - 3b 209 .word mcpm_power_up_setup_phys - 3b 210 .word mcpm_sync - 3b 211 .word first_man_locks - 3b 212 213ENDPROC(mcpm_entry_point) 214 215 .bss 216 217 .align CACHE_WRITEBACK_ORDER 218 .type first_man_locks, #object 219first_man_locks: 220 .space VLOCK_SIZE * MAX_NR_CLUSTERS 221 .align CACHE_WRITEBACK_ORDER 222 223 .type mcpm_entry_vectors, #object 224ENTRY(mcpm_entry_vectors) 225 .space 4 * MAX_NR_CLUSTERS * MAX_CPUS_PER_CLUSTER 226 227 .type mcpm_entry_early_pokes, #object 228ENTRY(mcpm_entry_early_pokes) 229 .space 8 * MAX_NR_CLUSTERS * MAX_CPUS_PER_CLUSTER 230 231 .type mcpm_power_up_setup_phys, #object 232ENTRY(mcpm_power_up_setup_phys) 233 .space 4 @ set by mcpm_sync_init() 234