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+/*
+ * arch/arm/common/mcpm_head.S -- kernel entry point for multi-cluster PM
+ *
+ * Created by: Nicolas Pitre, March 2012
+ * Copyright: (C) 2012-2013 Linaro Limited
+ *
+ * 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.
+ *
+ *
+ * Refer to Documentation/arm/cluster-pm-race-avoidance.txt
+ * for details of the synchronisation algorithms used here.
+ */
+
+#include <linux/linkage.h>
+#include <asm/mcpm.h>
+#include <asm/assembler.h>
+
+#include "vlock.h"
+
+.if MCPM_SYNC_CLUSTER_CPUS
+.error "cpus must be the first member of struct mcpm_sync_struct"
+.endif
+
+ .macro pr_dbg string
+#if defined(CONFIG_DEBUG_LL) && defined(DEBUG)
+ b 1901f
+1902: .asciz "CPU"
+1903: .asciz " cluster"
+1904: .asciz ": \string"
+ .align
+1901: adr r0, 1902b
+ bl printascii
+ mov r0, r9
+ bl printhex2
+ adr r0, 1903b
+ bl printascii
+ mov r0, r10
+ bl printhex2
+ adr r0, 1904b
+ bl printascii
+#endif
+ .endm
+
+ .arm
+ .align
+
+ENTRY(mcpm_entry_point)
+
+ ARM_BE8(setend be)
+ THUMB( adr r12, BSYM(1f) )
+ THUMB( bx r12 )
+ THUMB( .thumb )
+1:
+ mrc p15, 0, r0, c0, c0, 5 @ MPIDR
+ ubfx r9, r0, #0, #8 @ r9 = cpu
+ ubfx r10, r0, #8, #8 @ r10 = cluster
+ mov r3, #MAX_CPUS_PER_CLUSTER
+ mla r4, r3, r10, r9 @ r4 = canonical CPU index
+ cmp r4, #(MAX_CPUS_PER_CLUSTER * MAX_NR_CLUSTERS)
+ blo 2f
+
+ /* We didn't expect this CPU. Try to cheaply make it quiet. */
+1: wfi
+ wfe
+ b 1b
+
+2: pr_dbg "kernel mcpm_entry_point\n"
+
+ /*
+ * MMU is off so we need to get to various variables in a
+ * position independent way.
+ */
+ adr r5, 3f
+ ldmia r5, {r0, r6, r7, r8, r11}
+ add r0, r5, r0 @ r0 = mcpm_entry_early_pokes
+ add r6, r5, r6 @ r6 = mcpm_entry_vectors
+ ldr r7, [r5, r7] @ r7 = mcpm_power_up_setup_phys
+ add r8, r5, r8 @ r8 = mcpm_sync
+ add r11, r5, r11 @ r11 = first_man_locks
+
+ @ Perform an early poke, if any
+ add r0, r0, r4, lsl #3
+ ldmia r0, {r0, r1}
+ teq r0, #0
+ strne r1, [r0]
+
+ mov r0, #MCPM_SYNC_CLUSTER_SIZE
+ mla r8, r0, r10, r8 @ r8 = sync cluster base
+
+ @ Signal that this CPU is coming UP:
+ mov r0, #CPU_COMING_UP
+ mov r5, #MCPM_SYNC_CPU_SIZE
+ mla r5, r9, r5, r8 @ r5 = sync cpu address
+ strb r0, [r5]
+
+ @ At this point, the cluster cannot unexpectedly enter the GOING_DOWN
+ @ state, because there is at least one active CPU (this CPU).
+
+ mov r0, #VLOCK_SIZE
+ mla r11, r0, r10, r11 @ r11 = cluster first man lock
+ mov r0, r11
+ mov r1, r9 @ cpu
+ bl vlock_trylock @ implies DMB
+
+ cmp r0, #0 @ failed to get the lock?
+ bne mcpm_setup_wait @ wait for cluster setup if so
+
+ ldrb r0, [r8, #MCPM_SYNC_CLUSTER_CLUSTER]
+ cmp r0, #CLUSTER_UP @ cluster already up?
+ bne mcpm_setup @ if not, set up the cluster
+
+ @ Otherwise, release the first man lock and skip setup:
+ mov r0, r11
+ bl vlock_unlock
+ b mcpm_setup_complete
+
+mcpm_setup:
+ @ Control dependency implies strb not observable before previous ldrb.
+
+ @ Signal that the cluster is being brought up:
+ mov r0, #INBOUND_COMING_UP
+ strb r0, [r8, #MCPM_SYNC_CLUSTER_INBOUND]
+ dmb
+
+ @ Any CPU trying to take the cluster into CLUSTER_GOING_DOWN from this
+ @ point onwards will observe INBOUND_COMING_UP and abort.
+
+ @ Wait for any previously-pending cluster teardown operations to abort
+ @ or complete:
+mcpm_teardown_wait:
+ ldrb r0, [r8, #MCPM_SYNC_CLUSTER_CLUSTER]
+ cmp r0, #CLUSTER_GOING_DOWN
+ bne first_man_setup
+ wfe
+ b mcpm_teardown_wait
+
+first_man_setup:
+ dmb
+
+ @ If the outbound gave up before teardown started, skip cluster setup:
+
+ cmp r0, #CLUSTER_UP
+ beq mcpm_setup_leave
+
+ @ power_up_setup is now responsible for setting up the cluster:
+
+ cmp r7, #0
+ mov r0, #1 @ second (cluster) affinity level
+ blxne r7 @ Call power_up_setup if defined
+ dmb
+
+ mov r0, #CLUSTER_UP
+ strb r0, [r8, #MCPM_SYNC_CLUSTER_CLUSTER]
+ dmb
+
+mcpm_setup_leave:
+ @ Leave the cluster setup critical section:
+
+ mov r0, #INBOUND_NOT_COMING_UP
+ strb r0, [r8, #MCPM_SYNC_CLUSTER_INBOUND]
+ dsb st
+ sev
+
+ mov r0, r11
+ bl vlock_unlock @ implies DMB
+ b mcpm_setup_complete
+
+ @ In the contended case, non-first men wait here for cluster setup
+ @ to complete:
+mcpm_setup_wait:
+ ldrb r0, [r8, #MCPM_SYNC_CLUSTER_CLUSTER]
+ cmp r0, #CLUSTER_UP
+ wfene
+ bne mcpm_setup_wait
+ dmb
+
+mcpm_setup_complete:
+ @ If a platform-specific CPU setup hook is needed, it is
+ @ called from here.
+
+ cmp r7, #0
+ mov r0, #0 @ first (CPU) affinity level
+ blxne r7 @ Call power_up_setup if defined
+ dmb
+
+ @ Mark the CPU as up:
+
+ mov r0, #CPU_UP
+ strb r0, [r5]
+
+ @ Observability order of CPU_UP and opening of the gate does not matter.
+
+mcpm_entry_gated:
+ ldr r5, [r6, r4, lsl #2] @ r5 = CPU entry vector
+ cmp r5, #0
+ wfeeq
+ beq mcpm_entry_gated
+ dmb
+
+ pr_dbg "released\n"
+ bx r5
+
+ .align 2
+
+3: .word mcpm_entry_early_pokes - .
+ .word mcpm_entry_vectors - 3b
+ .word mcpm_power_up_setup_phys - 3b
+ .word mcpm_sync - 3b
+ .word first_man_locks - 3b
+
+ENDPROC(mcpm_entry_point)
+
+ .bss
+
+ .align CACHE_WRITEBACK_ORDER
+ .type first_man_locks, #object
+first_man_locks:
+ .space VLOCK_SIZE * MAX_NR_CLUSTERS
+ .align CACHE_WRITEBACK_ORDER
+
+ .type mcpm_entry_vectors, #object
+ENTRY(mcpm_entry_vectors)
+ .space 4 * MAX_NR_CLUSTERS * MAX_CPUS_PER_CLUSTER
+
+ .type mcpm_entry_early_pokes, #object
+ENTRY(mcpm_entry_early_pokes)
+ .space 8 * MAX_NR_CLUSTERS * MAX_CPUS_PER_CLUSTER
+
+ .type mcpm_power_up_setup_phys, #object
+ENTRY(mcpm_power_up_setup_phys)
+ .space 4 @ set by mcpm_sync_init()