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linux/arch/arm/common/mcpm_head.S

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ARM: multi-cluster PM: secondary kernel entry code CPUs in cluster based systems, such as big.LITTLE, have special needs when entering the kernel due to a hotplug event, or when resuming from a deep sleep mode. This is vectorized so multiple CPUs can enter the kernel in parallel without serialization. The mcpm prefix stands for "multi cluster power management", however this is usable on single cluster systems as well. Only the basic structure is introduced here. This will be extended with later patches. In order not to complexify things more than they currently have to, the planned work to make runtime adjusted MPIDR based indexing and dynamic memory allocation for cluster states is postponed to a later cycle. The MAX_NR_CLUSTERS and MAX_CPUS_PER_CLUSTER static definitions should be sufficient for those systems expected to be available in the near future. Signed-off-by: Nicolas Pitre <nico@linaro.org> Reviewed-by: Santosh Shilimkar <santosh.shilimkar@ti.com> Reviewed-by: Will Deacon <will.deacon@arm.com>
2012-04-12 08:45:22 +02:00
/*
* 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.
ARM: mcpm: introduce helpers for platform coherency exit/setup This provides helper methods to coordinate between CPUs coming down and CPUs going up, as well as documentation on the used algorithms, so that cluster teardown and setup operations are not done for a cluster simultaneously. For use in the power_down() implementation: * __mcpm_cpu_going_down(unsigned int cluster, unsigned int cpu) * __mcpm_outbound_enter_critical(unsigned int cluster) * __mcpm_outbound_leave_critical(unsigned int cluster) * __mcpm_cpu_down(unsigned int cluster, unsigned int cpu) The power_up_setup() helper should do platform-specific setup in preparation for turning the CPU on, such as invalidating local caches or entering coherency. It must be assembler for now, since it must run before the MMU can be switched on. It is passed the affinity level for which initialization should be performed. Because the mcpm_sync_struct content is looked-up and modified with the cache enabled or disabled depending on the code path, it is crucial to always ensure proper cache maintenance to update main memory right away. The sync_cache_*() helpers are used to that end. Also, in order to prevent a cached writer from interfering with an adjacent non-cached writer, we ensure each state variable is located to a separate cache line. Thanks to Nicolas Pitre and Achin Gupta for the help with this patch. Signed-off-by: Dave Martin <dave.martin@linaro.org> Signed-off-by: Nicolas Pitre <nico@linaro.org> Reviewed-by: Will Deacon <will.deacon@arm.com>
2012-07-17 15:25:42 +02:00
*
*
* Refer to Documentation/arm/cluster-pm-race-avoidance.txt
* for details of the synchronisation algorithms used here.
ARM: multi-cluster PM: secondary kernel entry code CPUs in cluster based systems, such as big.LITTLE, have special needs when entering the kernel due to a hotplug event, or when resuming from a deep sleep mode. This is vectorized so multiple CPUs can enter the kernel in parallel without serialization. The mcpm prefix stands for "multi cluster power management", however this is usable on single cluster systems as well. Only the basic structure is introduced here. This will be extended with later patches. In order not to complexify things more than they currently have to, the planned work to make runtime adjusted MPIDR based indexing and dynamic memory allocation for cluster states is postponed to a later cycle. The MAX_NR_CLUSTERS and MAX_CPUS_PER_CLUSTER static definitions should be sufficient for those systems expected to be available in the near future. Signed-off-by: Nicolas Pitre <nico@linaro.org> Reviewed-by: Santosh Shilimkar <santosh.shilimkar@ti.com> Reviewed-by: Will Deacon <will.deacon@arm.com>
2012-04-12 08:45:22 +02:00
*/
#include <linux/linkage.h>
#include <asm/mcpm.h>
ARM: mcpm_head.S: vlock-based first man election Instead of requiring the first man to be elected in advance (which can be suboptimal in some situations), this patch uses a per- cluster mutex to co-ordinate selection of the first man. This should also make it more feasible to reuse this code path for asynchronous cluster resume (as in CPUidle scenarios). We must ensure that the vlock data doesn't share a cacheline with anything else, or dirty cache eviction could corrupt it. Signed-off-by: Dave Martin <dave.martin@linaro.org> Signed-off-by: Nicolas Pitre <nicolas.pitre@linaro.org> Reviewed-by: Santosh Shilimkar <santosh.shilimkar@ti.com> Reviewed-by: Will Deacon <will.deacon@arm.com>
2012-08-17 17:07:02 +02:00
#include "vlock.h"
ARM: mcpm: introduce helpers for platform coherency exit/setup This provides helper methods to coordinate between CPUs coming down and CPUs going up, as well as documentation on the used algorithms, so that cluster teardown and setup operations are not done for a cluster simultaneously. For use in the power_down() implementation: * __mcpm_cpu_going_down(unsigned int cluster, unsigned int cpu) * __mcpm_outbound_enter_critical(unsigned int cluster) * __mcpm_outbound_leave_critical(unsigned int cluster) * __mcpm_cpu_down(unsigned int cluster, unsigned int cpu) The power_up_setup() helper should do platform-specific setup in preparation for turning the CPU on, such as invalidating local caches or entering coherency. It must be assembler for now, since it must run before the MMU can be switched on. It is passed the affinity level for which initialization should be performed. Because the mcpm_sync_struct content is looked-up and modified with the cache enabled or disabled depending on the code path, it is crucial to always ensure proper cache maintenance to update main memory right away. The sync_cache_*() helpers are used to that end. Also, in order to prevent a cached writer from interfering with an adjacent non-cached writer, we ensure each state variable is located to a separate cache line. Thanks to Nicolas Pitre and Achin Gupta for the help with this patch. Signed-off-by: Dave Martin <dave.martin@linaro.org> Signed-off-by: Nicolas Pitre <nico@linaro.org> Reviewed-by: Will Deacon <will.deacon@arm.com>
2012-07-17 15:25:42 +02:00
.if MCPM_SYNC_CLUSTER_CPUS
.error "cpus must be the first member of struct mcpm_sync_struct"
.endif
ARM: multi-cluster PM: secondary kernel entry code CPUs in cluster based systems, such as big.LITTLE, have special needs when entering the kernel due to a hotplug event, or when resuming from a deep sleep mode. This is vectorized so multiple CPUs can enter the kernel in parallel without serialization. The mcpm prefix stands for "multi cluster power management", however this is usable on single cluster systems as well. Only the basic structure is introduced here. This will be extended with later patches. In order not to complexify things more than they currently have to, the planned work to make runtime adjusted MPIDR based indexing and dynamic memory allocation for cluster states is postponed to a later cycle. The MAX_NR_CLUSTERS and MAX_CPUS_PER_CLUSTER static definitions should be sufficient for those systems expected to be available in the near future. Signed-off-by: Nicolas Pitre <nico@linaro.org> Reviewed-by: Santosh Shilimkar <santosh.shilimkar@ti.com> Reviewed-by: Will Deacon <will.deacon@arm.com>
2012-04-12 08:45:22 +02:00
.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
ARM: 7740/1: MCPM: prettify debug output The CPU and cluster numbers (MPIDR affinity levels 0 and 1) may have at most 8 bits each. Signed-off-by: Nicolas Pitre <nico@linaro.org> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2013-05-31 06:17:29 +02:00
bl printhex2
ARM: multi-cluster PM: secondary kernel entry code CPUs in cluster based systems, such as big.LITTLE, have special needs when entering the kernel due to a hotplug event, or when resuming from a deep sleep mode. This is vectorized so multiple CPUs can enter the kernel in parallel without serialization. The mcpm prefix stands for "multi cluster power management", however this is usable on single cluster systems as well. Only the basic structure is introduced here. This will be extended with later patches. In order not to complexify things more than they currently have to, the planned work to make runtime adjusted MPIDR based indexing and dynamic memory allocation for cluster states is postponed to a later cycle. The MAX_NR_CLUSTERS and MAX_CPUS_PER_CLUSTER static definitions should be sufficient for those systems expected to be available in the near future. Signed-off-by: Nicolas Pitre <nico@linaro.org> Reviewed-by: Santosh Shilimkar <santosh.shilimkar@ti.com> Reviewed-by: Will Deacon <will.deacon@arm.com>
2012-04-12 08:45:22 +02:00
adr r0, 1903b
bl printascii
mov r0, r10
ARM: 7740/1: MCPM: prettify debug output The CPU and cluster numbers (MPIDR affinity levels 0 and 1) may have at most 8 bits each. Signed-off-by: Nicolas Pitre <nico@linaro.org> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2013-05-31 06:17:29 +02:00
bl printhex2
ARM: multi-cluster PM: secondary kernel entry code CPUs in cluster based systems, such as big.LITTLE, have special needs when entering the kernel due to a hotplug event, or when resuming from a deep sleep mode. This is vectorized so multiple CPUs can enter the kernel in parallel without serialization. The mcpm prefix stands for "multi cluster power management", however this is usable on single cluster systems as well. Only the basic structure is introduced here. This will be extended with later patches. In order not to complexify things more than they currently have to, the planned work to make runtime adjusted MPIDR based indexing and dynamic memory allocation for cluster states is postponed to a later cycle. The MAX_NR_CLUSTERS and MAX_CPUS_PER_CLUSTER static definitions should be sufficient for those systems expected to be available in the near future. Signed-off-by: Nicolas Pitre <nico@linaro.org> Reviewed-by: Santosh Shilimkar <santosh.shilimkar@ti.com> Reviewed-by: Will Deacon <will.deacon@arm.com>
2012-04-12 08:45:22 +02:00
adr r0, 1904b
bl printascii
#endif
.endm
.arm
.align
ENTRY(mcpm_entry_point)
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"
/*
ARM: mcpm: introduce helpers for platform coherency exit/setup This provides helper methods to coordinate between CPUs coming down and CPUs going up, as well as documentation on the used algorithms, so that cluster teardown and setup operations are not done for a cluster simultaneously. For use in the power_down() implementation: * __mcpm_cpu_going_down(unsigned int cluster, unsigned int cpu) * __mcpm_outbound_enter_critical(unsigned int cluster) * __mcpm_outbound_leave_critical(unsigned int cluster) * __mcpm_cpu_down(unsigned int cluster, unsigned int cpu) The power_up_setup() helper should do platform-specific setup in preparation for turning the CPU on, such as invalidating local caches or entering coherency. It must be assembler for now, since it must run before the MMU can be switched on. It is passed the affinity level for which initialization should be performed. Because the mcpm_sync_struct content is looked-up and modified with the cache enabled or disabled depending on the code path, it is crucial to always ensure proper cache maintenance to update main memory right away. The sync_cache_*() helpers are used to that end. Also, in order to prevent a cached writer from interfering with an adjacent non-cached writer, we ensure each state variable is located to a separate cache line. Thanks to Nicolas Pitre and Achin Gupta for the help with this patch. Signed-off-by: Dave Martin <dave.martin@linaro.org> Signed-off-by: Nicolas Pitre <nico@linaro.org> Reviewed-by: Will Deacon <will.deacon@arm.com>
2012-07-17 15:25:42 +02:00
* MMU is off so we need to get to various variables in a
ARM: multi-cluster PM: secondary kernel entry code CPUs in cluster based systems, such as big.LITTLE, have special needs when entering the kernel due to a hotplug event, or when resuming from a deep sleep mode. This is vectorized so multiple CPUs can enter the kernel in parallel without serialization. The mcpm prefix stands for "multi cluster power management", however this is usable on single cluster systems as well. Only the basic structure is introduced here. This will be extended with later patches. In order not to complexify things more than they currently have to, the planned work to make runtime adjusted MPIDR based indexing and dynamic memory allocation for cluster states is postponed to a later cycle. The MAX_NR_CLUSTERS and MAX_CPUS_PER_CLUSTER static definitions should be sufficient for those systems expected to be available in the near future. Signed-off-by: Nicolas Pitre <nico@linaro.org> Reviewed-by: Santosh Shilimkar <santosh.shilimkar@ti.com> Reviewed-by: Will Deacon <will.deacon@arm.com>
2012-04-12 08:45:22 +02:00
* position independent way.
*/
adr r5, 3f
ARM: mcpm_head.S: vlock-based first man election Instead of requiring the first man to be elected in advance (which can be suboptimal in some situations), this patch uses a per- cluster mutex to co-ordinate selection of the first man. This should also make it more feasible to reuse this code path for asynchronous cluster resume (as in CPUidle scenarios). We must ensure that the vlock data doesn't share a cacheline with anything else, or dirty cache eviction could corrupt it. Signed-off-by: Dave Martin <dave.martin@linaro.org> Signed-off-by: Nicolas Pitre <nicolas.pitre@linaro.org> Reviewed-by: Santosh Shilimkar <santosh.shilimkar@ti.com> Reviewed-by: Will Deacon <will.deacon@arm.com>
2012-08-17 17:07:02 +02:00
ldmia r5, {r6, r7, r8, r11}
ARM: multi-cluster PM: secondary kernel entry code CPUs in cluster based systems, such as big.LITTLE, have special needs when entering the kernel due to a hotplug event, or when resuming from a deep sleep mode. This is vectorized so multiple CPUs can enter the kernel in parallel without serialization. The mcpm prefix stands for "multi cluster power management", however this is usable on single cluster systems as well. Only the basic structure is introduced here. This will be extended with later patches. In order not to complexify things more than they currently have to, the planned work to make runtime adjusted MPIDR based indexing and dynamic memory allocation for cluster states is postponed to a later cycle. The MAX_NR_CLUSTERS and MAX_CPUS_PER_CLUSTER static definitions should be sufficient for those systems expected to be available in the near future. Signed-off-by: Nicolas Pitre <nico@linaro.org> Reviewed-by: Santosh Shilimkar <santosh.shilimkar@ti.com> Reviewed-by: Will Deacon <will.deacon@arm.com>
2012-04-12 08:45:22 +02:00
add r6, r5, r6 @ r6 = mcpm_entry_vectors
ARM: mcpm: introduce helpers for platform coherency exit/setup This provides helper methods to coordinate between CPUs coming down and CPUs going up, as well as documentation on the used algorithms, so that cluster teardown and setup operations are not done for a cluster simultaneously. For use in the power_down() implementation: * __mcpm_cpu_going_down(unsigned int cluster, unsigned int cpu) * __mcpm_outbound_enter_critical(unsigned int cluster) * __mcpm_outbound_leave_critical(unsigned int cluster) * __mcpm_cpu_down(unsigned int cluster, unsigned int cpu) The power_up_setup() helper should do platform-specific setup in preparation for turning the CPU on, such as invalidating local caches or entering coherency. It must be assembler for now, since it must run before the MMU can be switched on. It is passed the affinity level for which initialization should be performed. Because the mcpm_sync_struct content is looked-up and modified with the cache enabled or disabled depending on the code path, it is crucial to always ensure proper cache maintenance to update main memory right away. The sync_cache_*() helpers are used to that end. Also, in order to prevent a cached writer from interfering with an adjacent non-cached writer, we ensure each state variable is located to a separate cache line. Thanks to Nicolas Pitre and Achin Gupta for the help with this patch. Signed-off-by: Dave Martin <dave.martin@linaro.org> Signed-off-by: Nicolas Pitre <nico@linaro.org> Reviewed-by: Will Deacon <will.deacon@arm.com>
2012-07-17 15:25:42 +02:00
ldr r7, [r5, r7] @ r7 = mcpm_power_up_setup_phys
add r8, r5, r8 @ r8 = mcpm_sync
ARM: mcpm_head.S: vlock-based first man election Instead of requiring the first man to be elected in advance (which can be suboptimal in some situations), this patch uses a per- cluster mutex to co-ordinate selection of the first man. This should also make it more feasible to reuse this code path for asynchronous cluster resume (as in CPUidle scenarios). We must ensure that the vlock data doesn't share a cacheline with anything else, or dirty cache eviction could corrupt it. Signed-off-by: Dave Martin <dave.martin@linaro.org> Signed-off-by: Nicolas Pitre <nicolas.pitre@linaro.org> Reviewed-by: Santosh Shilimkar <santosh.shilimkar@ti.com> Reviewed-by: Will Deacon <will.deacon@arm.com>
2012-08-17 17:07:02 +02:00
add r11, r5, r11 @ r11 = first_man_locks
ARM: mcpm: introduce helpers for platform coherency exit/setup This provides helper methods to coordinate between CPUs coming down and CPUs going up, as well as documentation on the used algorithms, so that cluster teardown and setup operations are not done for a cluster simultaneously. For use in the power_down() implementation: * __mcpm_cpu_going_down(unsigned int cluster, unsigned int cpu) * __mcpm_outbound_enter_critical(unsigned int cluster) * __mcpm_outbound_leave_critical(unsigned int cluster) * __mcpm_cpu_down(unsigned int cluster, unsigned int cpu) The power_up_setup() helper should do platform-specific setup in preparation for turning the CPU on, such as invalidating local caches or entering coherency. It must be assembler for now, since it must run before the MMU can be switched on. It is passed the affinity level for which initialization should be performed. Because the mcpm_sync_struct content is looked-up and modified with the cache enabled or disabled depending on the code path, it is crucial to always ensure proper cache maintenance to update main memory right away. The sync_cache_*() helpers are used to that end. Also, in order to prevent a cached writer from interfering with an adjacent non-cached writer, we ensure each state variable is located to a separate cache line. Thanks to Nicolas Pitre and Achin Gupta for the help with this patch. Signed-off-by: Dave Martin <dave.martin@linaro.org> Signed-off-by: Nicolas Pitre <nico@linaro.org> Reviewed-by: Will Deacon <will.deacon@arm.com>
2012-07-17 15:25:42 +02:00
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).
ARM: mcpm_head.S: vlock-based first man election Instead of requiring the first man to be elected in advance (which can be suboptimal in some situations), this patch uses a per- cluster mutex to co-ordinate selection of the first man. This should also make it more feasible to reuse this code path for asynchronous cluster resume (as in CPUidle scenarios). We must ensure that the vlock data doesn't share a cacheline with anything else, or dirty cache eviction could corrupt it. Signed-off-by: Dave Martin <dave.martin@linaro.org> Signed-off-by: Nicolas Pitre <nicolas.pitre@linaro.org> Reviewed-by: Santosh Shilimkar <santosh.shilimkar@ti.com> Reviewed-by: Will Deacon <will.deacon@arm.com>
2012-08-17 17:07:02 +02:00
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
ARM: mcpm: introduce helpers for platform coherency exit/setup This provides helper methods to coordinate between CPUs coming down and CPUs going up, as well as documentation on the used algorithms, so that cluster teardown and setup operations are not done for a cluster simultaneously. For use in the power_down() implementation: * __mcpm_cpu_going_down(unsigned int cluster, unsigned int cpu) * __mcpm_outbound_enter_critical(unsigned int cluster) * __mcpm_outbound_leave_critical(unsigned int cluster) * __mcpm_cpu_down(unsigned int cluster, unsigned int cpu) The power_up_setup() helper should do platform-specific setup in preparation for turning the CPU on, such as invalidating local caches or entering coherency. It must be assembler for now, since it must run before the MMU can be switched on. It is passed the affinity level for which initialization should be performed. Because the mcpm_sync_struct content is looked-up and modified with the cache enabled or disabled depending on the code path, it is crucial to always ensure proper cache maintenance to update main memory right away. The sync_cache_*() helpers are used to that end. Also, in order to prevent a cached writer from interfering with an adjacent non-cached writer, we ensure each state variable is located to a separate cache line. Thanks to Nicolas Pitre and Achin Gupta for the help with this patch. Signed-off-by: Dave Martin <dave.martin@linaro.org> Signed-off-by: Nicolas Pitre <nico@linaro.org> Reviewed-by: Will Deacon <will.deacon@arm.com>
2012-07-17 15:25:42 +02:00
ldrb r0, [r8, #MCPM_SYNC_CLUSTER_CLUSTER]
cmp r0, #CLUSTER_UP @ cluster already up?
bne mcpm_setup @ if not, set up the cluster
ARM: mcpm_head.S: vlock-based first man election Instead of requiring the first man to be elected in advance (which can be suboptimal in some situations), this patch uses a per- cluster mutex to co-ordinate selection of the first man. This should also make it more feasible to reuse this code path for asynchronous cluster resume (as in CPUidle scenarios). We must ensure that the vlock data doesn't share a cacheline with anything else, or dirty cache eviction could corrupt it. Signed-off-by: Dave Martin <dave.martin@linaro.org> Signed-off-by: Nicolas Pitre <nicolas.pitre@linaro.org> Reviewed-by: Santosh Shilimkar <santosh.shilimkar@ti.com> Reviewed-by: Will Deacon <will.deacon@arm.com>
2012-08-17 17:07:02 +02:00
@ Otherwise, release the first man lock and skip setup:
mov r0, r11
bl vlock_unlock
ARM: mcpm: introduce helpers for platform coherency exit/setup This provides helper methods to coordinate between CPUs coming down and CPUs going up, as well as documentation on the used algorithms, so that cluster teardown and setup operations are not done for a cluster simultaneously. For use in the power_down() implementation: * __mcpm_cpu_going_down(unsigned int cluster, unsigned int cpu) * __mcpm_outbound_enter_critical(unsigned int cluster) * __mcpm_outbound_leave_critical(unsigned int cluster) * __mcpm_cpu_down(unsigned int cluster, unsigned int cpu) The power_up_setup() helper should do platform-specific setup in preparation for turning the CPU on, such as invalidating local caches or entering coherency. It must be assembler for now, since it must run before the MMU can be switched on. It is passed the affinity level for which initialization should be performed. Because the mcpm_sync_struct content is looked-up and modified with the cache enabled or disabled depending on the code path, it is crucial to always ensure proper cache maintenance to update main memory right away. The sync_cache_*() helpers are used to that end. Also, in order to prevent a cached writer from interfering with an adjacent non-cached writer, we ensure each state variable is located to a separate cache line. Thanks to Nicolas Pitre and Achin Gupta for the help with this patch. Signed-off-by: Dave Martin <dave.martin@linaro.org> Signed-off-by: Nicolas Pitre <nico@linaro.org> Reviewed-by: Will Deacon <will.deacon@arm.com>
2012-07-17 15:25:42 +02:00
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
sev
ARM: mcpm_head.S: vlock-based first man election Instead of requiring the first man to be elected in advance (which can be suboptimal in some situations), this patch uses a per- cluster mutex to co-ordinate selection of the first man. This should also make it more feasible to reuse this code path for asynchronous cluster resume (as in CPUidle scenarios). We must ensure that the vlock data doesn't share a cacheline with anything else, or dirty cache eviction could corrupt it. Signed-off-by: Dave Martin <dave.martin@linaro.org> Signed-off-by: Nicolas Pitre <nicolas.pitre@linaro.org> Reviewed-by: Santosh Shilimkar <santosh.shilimkar@ti.com> Reviewed-by: Will Deacon <will.deacon@arm.com>
2012-08-17 17:07:02 +02:00
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
ARM: mcpm: introduce helpers for platform coherency exit/setup This provides helper methods to coordinate between CPUs coming down and CPUs going up, as well as documentation on the used algorithms, so that cluster teardown and setup operations are not done for a cluster simultaneously. For use in the power_down() implementation: * __mcpm_cpu_going_down(unsigned int cluster, unsigned int cpu) * __mcpm_outbound_enter_critical(unsigned int cluster) * __mcpm_outbound_leave_critical(unsigned int cluster) * __mcpm_cpu_down(unsigned int cluster, unsigned int cpu) The power_up_setup() helper should do platform-specific setup in preparation for turning the CPU on, such as invalidating local caches or entering coherency. It must be assembler for now, since it must run before the MMU can be switched on. It is passed the affinity level for which initialization should be performed. Because the mcpm_sync_struct content is looked-up and modified with the cache enabled or disabled depending on the code path, it is crucial to always ensure proper cache maintenance to update main memory right away. The sync_cache_*() helpers are used to that end. Also, in order to prevent a cached writer from interfering with an adjacent non-cached writer, we ensure each state variable is located to a separate cache line. Thanks to Nicolas Pitre and Achin Gupta for the help with this patch. Signed-off-by: Dave Martin <dave.martin@linaro.org> Signed-off-by: Nicolas Pitre <nico@linaro.org> Reviewed-by: Will Deacon <will.deacon@arm.com>
2012-07-17 15:25:42 +02:00
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.
ARM: multi-cluster PM: secondary kernel entry code CPUs in cluster based systems, such as big.LITTLE, have special needs when entering the kernel due to a hotplug event, or when resuming from a deep sleep mode. This is vectorized so multiple CPUs can enter the kernel in parallel without serialization. The mcpm prefix stands for "multi cluster power management", however this is usable on single cluster systems as well. Only the basic structure is introduced here. This will be extended with later patches. In order not to complexify things more than they currently have to, the planned work to make runtime adjusted MPIDR based indexing and dynamic memory allocation for cluster states is postponed to a later cycle. The MAX_NR_CLUSTERS and MAX_CPUS_PER_CLUSTER static definitions should be sufficient for those systems expected to be available in the near future. Signed-off-by: Nicolas Pitre <nico@linaro.org> Reviewed-by: Santosh Shilimkar <santosh.shilimkar@ti.com> Reviewed-by: Will Deacon <will.deacon@arm.com>
2012-04-12 08:45:22 +02:00
mcpm_entry_gated:
ldr r5, [r6, r4, lsl #2] @ r5 = CPU entry vector
cmp r5, #0
wfeeq
beq mcpm_entry_gated
ARM: mcpm: introduce helpers for platform coherency exit/setup This provides helper methods to coordinate between CPUs coming down and CPUs going up, as well as documentation on the used algorithms, so that cluster teardown and setup operations are not done for a cluster simultaneously. For use in the power_down() implementation: * __mcpm_cpu_going_down(unsigned int cluster, unsigned int cpu) * __mcpm_outbound_enter_critical(unsigned int cluster) * __mcpm_outbound_leave_critical(unsigned int cluster) * __mcpm_cpu_down(unsigned int cluster, unsigned int cpu) The power_up_setup() helper should do platform-specific setup in preparation for turning the CPU on, such as invalidating local caches or entering coherency. It must be assembler for now, since it must run before the MMU can be switched on. It is passed the affinity level for which initialization should be performed. Because the mcpm_sync_struct content is looked-up and modified with the cache enabled or disabled depending on the code path, it is crucial to always ensure proper cache maintenance to update main memory right away. The sync_cache_*() helpers are used to that end. Also, in order to prevent a cached writer from interfering with an adjacent non-cached writer, we ensure each state variable is located to a separate cache line. Thanks to Nicolas Pitre and Achin Gupta for the help with this patch. Signed-off-by: Dave Martin <dave.martin@linaro.org> Signed-off-by: Nicolas Pitre <nico@linaro.org> Reviewed-by: Will Deacon <will.deacon@arm.com>
2012-07-17 15:25:42 +02:00
dmb
ARM: multi-cluster PM: secondary kernel entry code CPUs in cluster based systems, such as big.LITTLE, have special needs when entering the kernel due to a hotplug event, or when resuming from a deep sleep mode. This is vectorized so multiple CPUs can enter the kernel in parallel without serialization. The mcpm prefix stands for "multi cluster power management", however this is usable on single cluster systems as well. Only the basic structure is introduced here. This will be extended with later patches. In order not to complexify things more than they currently have to, the planned work to make runtime adjusted MPIDR based indexing and dynamic memory allocation for cluster states is postponed to a later cycle. The MAX_NR_CLUSTERS and MAX_CPUS_PER_CLUSTER static definitions should be sufficient for those systems expected to be available in the near future. Signed-off-by: Nicolas Pitre <nico@linaro.org> Reviewed-by: Santosh Shilimkar <santosh.shilimkar@ti.com> Reviewed-by: Will Deacon <will.deacon@arm.com>
2012-04-12 08:45:22 +02:00
pr_dbg "released\n"
bx r5
.align 2
3: .word mcpm_entry_vectors - .
ARM: mcpm: introduce helpers for platform coherency exit/setup This provides helper methods to coordinate between CPUs coming down and CPUs going up, as well as documentation on the used algorithms, so that cluster teardown and setup operations are not done for a cluster simultaneously. For use in the power_down() implementation: * __mcpm_cpu_going_down(unsigned int cluster, unsigned int cpu) * __mcpm_outbound_enter_critical(unsigned int cluster) * __mcpm_outbound_leave_critical(unsigned int cluster) * __mcpm_cpu_down(unsigned int cluster, unsigned int cpu) The power_up_setup() helper should do platform-specific setup in preparation for turning the CPU on, such as invalidating local caches or entering coherency. It must be assembler for now, since it must run before the MMU can be switched on. It is passed the affinity level for which initialization should be performed. Because the mcpm_sync_struct content is looked-up and modified with the cache enabled or disabled depending on the code path, it is crucial to always ensure proper cache maintenance to update main memory right away. The sync_cache_*() helpers are used to that end. Also, in order to prevent a cached writer from interfering with an adjacent non-cached writer, we ensure each state variable is located to a separate cache line. Thanks to Nicolas Pitre and Achin Gupta for the help with this patch. Signed-off-by: Dave Martin <dave.martin@linaro.org> Signed-off-by: Nicolas Pitre <nico@linaro.org> Reviewed-by: Will Deacon <will.deacon@arm.com>
2012-07-17 15:25:42 +02:00
.word mcpm_power_up_setup_phys - 3b
.word mcpm_sync - 3b
ARM: mcpm_head.S: vlock-based first man election Instead of requiring the first man to be elected in advance (which can be suboptimal in some situations), this patch uses a per- cluster mutex to co-ordinate selection of the first man. This should also make it more feasible to reuse this code path for asynchronous cluster resume (as in CPUidle scenarios). We must ensure that the vlock data doesn't share a cacheline with anything else, or dirty cache eviction could corrupt it. Signed-off-by: Dave Martin <dave.martin@linaro.org> Signed-off-by: Nicolas Pitre <nicolas.pitre@linaro.org> Reviewed-by: Santosh Shilimkar <santosh.shilimkar@ti.com> Reviewed-by: Will Deacon <will.deacon@arm.com>
2012-08-17 17:07:02 +02:00
.word first_man_locks - 3b
ARM: multi-cluster PM: secondary kernel entry code CPUs in cluster based systems, such as big.LITTLE, have special needs when entering the kernel due to a hotplug event, or when resuming from a deep sleep mode. This is vectorized so multiple CPUs can enter the kernel in parallel without serialization. The mcpm prefix stands for "multi cluster power management", however this is usable on single cluster systems as well. Only the basic structure is introduced here. This will be extended with later patches. In order not to complexify things more than they currently have to, the planned work to make runtime adjusted MPIDR based indexing and dynamic memory allocation for cluster states is postponed to a later cycle. The MAX_NR_CLUSTERS and MAX_CPUS_PER_CLUSTER static definitions should be sufficient for those systems expected to be available in the near future. Signed-off-by: Nicolas Pitre <nico@linaro.org> Reviewed-by: Santosh Shilimkar <santosh.shilimkar@ti.com> Reviewed-by: Will Deacon <will.deacon@arm.com>
2012-04-12 08:45:22 +02:00
ENDPROC(mcpm_entry_point)
.bss
ARM: mcpm_head.S: vlock-based first man election Instead of requiring the first man to be elected in advance (which can be suboptimal in some situations), this patch uses a per- cluster mutex to co-ordinate selection of the first man. This should also make it more feasible to reuse this code path for asynchronous cluster resume (as in CPUidle scenarios). We must ensure that the vlock data doesn't share a cacheline with anything else, or dirty cache eviction could corrupt it. Signed-off-by: Dave Martin <dave.martin@linaro.org> Signed-off-by: Nicolas Pitre <nicolas.pitre@linaro.org> Reviewed-by: Santosh Shilimkar <santosh.shilimkar@ti.com> Reviewed-by: Will Deacon <will.deacon@arm.com>
2012-08-17 17:07:02 +02:00
.align CACHE_WRITEBACK_ORDER
.type first_man_locks, #object
first_man_locks:
.space VLOCK_SIZE * MAX_NR_CLUSTERS
.align CACHE_WRITEBACK_ORDER
ARM: multi-cluster PM: secondary kernel entry code CPUs in cluster based systems, such as big.LITTLE, have special needs when entering the kernel due to a hotplug event, or when resuming from a deep sleep mode. This is vectorized so multiple CPUs can enter the kernel in parallel without serialization. The mcpm prefix stands for "multi cluster power management", however this is usable on single cluster systems as well. Only the basic structure is introduced here. This will be extended with later patches. In order not to complexify things more than they currently have to, the planned work to make runtime adjusted MPIDR based indexing and dynamic memory allocation for cluster states is postponed to a later cycle. The MAX_NR_CLUSTERS and MAX_CPUS_PER_CLUSTER static definitions should be sufficient for those systems expected to be available in the near future. Signed-off-by: Nicolas Pitre <nico@linaro.org> Reviewed-by: Santosh Shilimkar <santosh.shilimkar@ti.com> Reviewed-by: Will Deacon <will.deacon@arm.com>
2012-04-12 08:45:22 +02:00
.type mcpm_entry_vectors, #object
ENTRY(mcpm_entry_vectors)
.space 4 * MAX_NR_CLUSTERS * MAX_CPUS_PER_CLUSTER
ARM: mcpm: introduce helpers for platform coherency exit/setup This provides helper methods to coordinate between CPUs coming down and CPUs going up, as well as documentation on the used algorithms, so that cluster teardown and setup operations are not done for a cluster simultaneously. For use in the power_down() implementation: * __mcpm_cpu_going_down(unsigned int cluster, unsigned int cpu) * __mcpm_outbound_enter_critical(unsigned int cluster) * __mcpm_outbound_leave_critical(unsigned int cluster) * __mcpm_cpu_down(unsigned int cluster, unsigned int cpu) The power_up_setup() helper should do platform-specific setup in preparation for turning the CPU on, such as invalidating local caches or entering coherency. It must be assembler for now, since it must run before the MMU can be switched on. It is passed the affinity level for which initialization should be performed. Because the mcpm_sync_struct content is looked-up and modified with the cache enabled or disabled depending on the code path, it is crucial to always ensure proper cache maintenance to update main memory right away. The sync_cache_*() helpers are used to that end. Also, in order to prevent a cached writer from interfering with an adjacent non-cached writer, we ensure each state variable is located to a separate cache line. Thanks to Nicolas Pitre and Achin Gupta for the help with this patch. Signed-off-by: Dave Martin <dave.martin@linaro.org> Signed-off-by: Nicolas Pitre <nico@linaro.org> Reviewed-by: Will Deacon <will.deacon@arm.com>
2012-07-17 15:25:42 +02:00
.type mcpm_power_up_setup_phys, #object
ENTRY(mcpm_power_up_setup_phys)
.space 4 @ set by mcpm_sync_init()