OpenCloudOS-Kernel/arch/arm64/kernel/sleep.S

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arm64: kernel: cpu_{suspend/resume} implementation Kernel subsystems like CPU idle and suspend to RAM require a generic mechanism to suspend a processor, save its context and put it into a quiescent state. The cpu_{suspend}/{resume} implementation provides such a framework through a kernel interface allowing to save/restore registers, flush the context to DRAM and suspend/resume to/from low-power states where processor context may be lost. The CPU suspend implementation relies on the suspend protocol registered in CPU operations to carry out a suspend request after context is saved and flushed to DRAM. The cpu_suspend interface: int cpu_suspend(unsigned long arg); allows to pass an opaque parameter that is handed over to the suspend CPU operations back-end so that it can take action according to the semantics attached to it. The arg parameter allows suspend to RAM and CPU idle drivers to communicate to suspend protocol back-ends; it requires standardization so that the interface can be reused seamlessly across systems, paving the way for generic drivers. Context memory is allocated on the stack, whose address is stashed in a per-cpu variable to keep track of it and passed to core functions that save/restore the registers required by the architecture. Even though, upon successful execution, the cpu_suspend function shuts down the suspending processor, the warm boot resume mechanism, based on the cpu_resume function, makes the resume path operate as a cpu_suspend function return, so that cpu_suspend can be treated as a C function by the caller, which simplifies coding the PM drivers that rely on the cpu_suspend API. Upon context save, the minimal amount of memory is flushed to DRAM so that it can be retrieved when the MMU is off and caches are not searched. The suspend CPU operation, depending on the required operations (eg CPU vs Cluster shutdown) is in charge of flushing the cache hierarchy either implicitly (by calling firmware implementations like PSCI) or explicitly by executing the required cache maintainance functions. Debug exceptions are disabled during cpu_{suspend}/{resume} operations so that debug registers can be saved and restored properly preventing preemption from debug agents enabled in the kernel. Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
2013-07-22 19:22:13 +08:00
#include <linux/errno.h>
#include <linux/linkage.h>
#include <asm/asm-offsets.h>
#include <asm/assembler.h>
.text
/*
* Implementation of MPIDR_EL1 hash algorithm through shifting
* and OR'ing.
*
* @dst: register containing hash result
* @rs0: register containing affinity level 0 bit shift
* @rs1: register containing affinity level 1 bit shift
* @rs2: register containing affinity level 2 bit shift
* @rs3: register containing affinity level 3 bit shift
* @mpidr: register containing MPIDR_EL1 value
* @mask: register containing MPIDR mask
*
* Pseudo C-code:
*
*u32 dst;
*
*compute_mpidr_hash(u32 rs0, u32 rs1, u32 rs2, u32 rs3, u64 mpidr, u64 mask) {
* u32 aff0, aff1, aff2, aff3;
* u64 mpidr_masked = mpidr & mask;
* aff0 = mpidr_masked & 0xff;
* aff1 = mpidr_masked & 0xff00;
* aff2 = mpidr_masked & 0xff0000;
* aff2 = mpidr_masked & 0xff00000000;
* dst = (aff0 >> rs0 | aff1 >> rs1 | aff2 >> rs2 | aff3 >> rs3);
*}
* Input registers: rs0, rs1, rs2, rs3, mpidr, mask
* Output register: dst
* Note: input and output registers must be disjoint register sets
(eg: a macro instance with mpidr = x1 and dst = x1 is invalid)
*/
.macro compute_mpidr_hash dst, rs0, rs1, rs2, rs3, mpidr, mask
and \mpidr, \mpidr, \mask // mask out MPIDR bits
and \dst, \mpidr, #0xff // mask=aff0
lsr \dst ,\dst, \rs0 // dst=aff0>>rs0
and \mask, \mpidr, #0xff00 // mask = aff1
lsr \mask ,\mask, \rs1
orr \dst, \dst, \mask // dst|=(aff1>>rs1)
and \mask, \mpidr, #0xff0000 // mask = aff2
lsr \mask ,\mask, \rs2
orr \dst, \dst, \mask // dst|=(aff2>>rs2)
and \mask, \mpidr, #0xff00000000 // mask = aff3
lsr \mask ,\mask, \rs3
orr \dst, \dst, \mask // dst|=(aff3>>rs3)
.endm
/*
arm64: kernel: refactor the CPU suspend API for retention states CPU suspend is the standard kernel interface to be used to enter low-power states on ARM64 systems. Current cpu_suspend implementation by default assumes that all low power states are losing the CPU context, so the CPU registers must be saved and cleaned to DRAM upon state entry. Furthermore, the current cpu_suspend() implementation assumes that if the CPU suspend back-end method returns when called, this has to be considered an error regardless of the return code (which can be successful) since the CPU was not expected to return from a code path that is different from cpu_resume code path - eg returning from the reset vector. All in all this means that the current API does not cope well with low-power states that preserve the CPU context when entered (ie retention states), since first of all the context is saved for nothing on state entry for those states and a successful state entry can return as a normal function return, which is considered an error by the current CPU suspend implementation. This patch refactors the cpu_suspend() API so that it can be split in two separate functionalities. The arm64 cpu_suspend API just provides a wrapper around CPU suspend operation hook. A new function is introduced (for architecture code use only) for states that require context saving upon entry: __cpu_suspend(unsigned long arg, int (*fn)(unsigned long)) __cpu_suspend() saves the context on function entry and calls the so called suspend finisher (ie fn) to complete the suspend operation. The finisher is not expected to return, unless it fails in which case the error is propagated back to the __cpu_suspend caller. The API refactoring results in the following pseudo code call sequence for a suspending CPU, when triggered from a kernel subsystem: /* * int cpu_suspend(unsigned long idx) * @idx: idle state index */ { -> cpu_suspend(idx) |---> CPU operations suspend hook called, if present |--> if (retention_state) |--> direct suspend back-end call (eg PSCI suspend) else |--> __cpu_suspend(idx, &back_end_finisher); } By refactoring the cpu_suspend API this way, the CPU operations back-end has a chance to detect whether idle states require state saving or not and can call the required suspend operations accordingly either through simple function call or indirectly through __cpu_suspend() which carries out state saving and suspend finisher dispatching to complete idle state entry. Reviewed-by: Catalin Marinas <catalin.marinas@arm.com> Reviewed-by: Hanjun Guo <hanjun.guo@linaro.org> Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2014-08-07 21:54:50 +08:00
* Save CPU state for a suspend and execute the suspend finisher.
* On success it will return 0 through cpu_resume - ie through a CPU
* soft/hard reboot from the reset vector.
* On failure it returns the suspend finisher return value or force
* -EOPNOTSUPP if the finisher erroneously returns 0 (the suspend finisher
* is not allowed to return, if it does this must be considered failure).
* It saves callee registers, and allocates space on the kernel stack
* to save the CPU specific registers + some other data for resume.
arm64: kernel: cpu_{suspend/resume} implementation Kernel subsystems like CPU idle and suspend to RAM require a generic mechanism to suspend a processor, save its context and put it into a quiescent state. The cpu_{suspend}/{resume} implementation provides such a framework through a kernel interface allowing to save/restore registers, flush the context to DRAM and suspend/resume to/from low-power states where processor context may be lost. The CPU suspend implementation relies on the suspend protocol registered in CPU operations to carry out a suspend request after context is saved and flushed to DRAM. The cpu_suspend interface: int cpu_suspend(unsigned long arg); allows to pass an opaque parameter that is handed over to the suspend CPU operations back-end so that it can take action according to the semantics attached to it. The arg parameter allows suspend to RAM and CPU idle drivers to communicate to suspend protocol back-ends; it requires standardization so that the interface can be reused seamlessly across systems, paving the way for generic drivers. Context memory is allocated on the stack, whose address is stashed in a per-cpu variable to keep track of it and passed to core functions that save/restore the registers required by the architecture. Even though, upon successful execution, the cpu_suspend function shuts down the suspending processor, the warm boot resume mechanism, based on the cpu_resume function, makes the resume path operate as a cpu_suspend function return, so that cpu_suspend can be treated as a C function by the caller, which simplifies coding the PM drivers that rely on the cpu_suspend API. Upon context save, the minimal amount of memory is flushed to DRAM so that it can be retrieved when the MMU is off and caches are not searched. The suspend CPU operation, depending on the required operations (eg CPU vs Cluster shutdown) is in charge of flushing the cache hierarchy either implicitly (by calling firmware implementations like PSCI) or explicitly by executing the required cache maintainance functions. Debug exceptions are disabled during cpu_{suspend}/{resume} operations so that debug registers can be saved and restored properly preventing preemption from debug agents enabled in the kernel. Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
2013-07-22 19:22:13 +08:00
*
* x0 = suspend finisher argument
arm64: kernel: refactor the CPU suspend API for retention states CPU suspend is the standard kernel interface to be used to enter low-power states on ARM64 systems. Current cpu_suspend implementation by default assumes that all low power states are losing the CPU context, so the CPU registers must be saved and cleaned to DRAM upon state entry. Furthermore, the current cpu_suspend() implementation assumes that if the CPU suspend back-end method returns when called, this has to be considered an error regardless of the return code (which can be successful) since the CPU was not expected to return from a code path that is different from cpu_resume code path - eg returning from the reset vector. All in all this means that the current API does not cope well with low-power states that preserve the CPU context when entered (ie retention states), since first of all the context is saved for nothing on state entry for those states and a successful state entry can return as a normal function return, which is considered an error by the current CPU suspend implementation. This patch refactors the cpu_suspend() API so that it can be split in two separate functionalities. The arm64 cpu_suspend API just provides a wrapper around CPU suspend operation hook. A new function is introduced (for architecture code use only) for states that require context saving upon entry: __cpu_suspend(unsigned long arg, int (*fn)(unsigned long)) __cpu_suspend() saves the context on function entry and calls the so called suspend finisher (ie fn) to complete the suspend operation. The finisher is not expected to return, unless it fails in which case the error is propagated back to the __cpu_suspend caller. The API refactoring results in the following pseudo code call sequence for a suspending CPU, when triggered from a kernel subsystem: /* * int cpu_suspend(unsigned long idx) * @idx: idle state index */ { -> cpu_suspend(idx) |---> CPU operations suspend hook called, if present |--> if (retention_state) |--> direct suspend back-end call (eg PSCI suspend) else |--> __cpu_suspend(idx, &back_end_finisher); } By refactoring the cpu_suspend API this way, the CPU operations back-end has a chance to detect whether idle states require state saving or not and can call the required suspend operations accordingly either through simple function call or indirectly through __cpu_suspend() which carries out state saving and suspend finisher dispatching to complete idle state entry. Reviewed-by: Catalin Marinas <catalin.marinas@arm.com> Reviewed-by: Hanjun Guo <hanjun.guo@linaro.org> Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2014-08-07 21:54:50 +08:00
* x1 = suspend finisher function pointer
arm64: kernel: cpu_{suspend/resume} implementation Kernel subsystems like CPU idle and suspend to RAM require a generic mechanism to suspend a processor, save its context and put it into a quiescent state. The cpu_{suspend}/{resume} implementation provides such a framework through a kernel interface allowing to save/restore registers, flush the context to DRAM and suspend/resume to/from low-power states where processor context may be lost. The CPU suspend implementation relies on the suspend protocol registered in CPU operations to carry out a suspend request after context is saved and flushed to DRAM. The cpu_suspend interface: int cpu_suspend(unsigned long arg); allows to pass an opaque parameter that is handed over to the suspend CPU operations back-end so that it can take action according to the semantics attached to it. The arg parameter allows suspend to RAM and CPU idle drivers to communicate to suspend protocol back-ends; it requires standardization so that the interface can be reused seamlessly across systems, paving the way for generic drivers. Context memory is allocated on the stack, whose address is stashed in a per-cpu variable to keep track of it and passed to core functions that save/restore the registers required by the architecture. Even though, upon successful execution, the cpu_suspend function shuts down the suspending processor, the warm boot resume mechanism, based on the cpu_resume function, makes the resume path operate as a cpu_suspend function return, so that cpu_suspend can be treated as a C function by the caller, which simplifies coding the PM drivers that rely on the cpu_suspend API. Upon context save, the minimal amount of memory is flushed to DRAM so that it can be retrieved when the MMU is off and caches are not searched. The suspend CPU operation, depending on the required operations (eg CPU vs Cluster shutdown) is in charge of flushing the cache hierarchy either implicitly (by calling firmware implementations like PSCI) or explicitly by executing the required cache maintainance functions. Debug exceptions are disabled during cpu_{suspend}/{resume} operations so that debug registers can be saved and restored properly preventing preemption from debug agents enabled in the kernel. Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
2013-07-22 19:22:13 +08:00
*/
arm64: kernel: refactor the CPU suspend API for retention states CPU suspend is the standard kernel interface to be used to enter low-power states on ARM64 systems. Current cpu_suspend implementation by default assumes that all low power states are losing the CPU context, so the CPU registers must be saved and cleaned to DRAM upon state entry. Furthermore, the current cpu_suspend() implementation assumes that if the CPU suspend back-end method returns when called, this has to be considered an error regardless of the return code (which can be successful) since the CPU was not expected to return from a code path that is different from cpu_resume code path - eg returning from the reset vector. All in all this means that the current API does not cope well with low-power states that preserve the CPU context when entered (ie retention states), since first of all the context is saved for nothing on state entry for those states and a successful state entry can return as a normal function return, which is considered an error by the current CPU suspend implementation. This patch refactors the cpu_suspend() API so that it can be split in two separate functionalities. The arm64 cpu_suspend API just provides a wrapper around CPU suspend operation hook. A new function is introduced (for architecture code use only) for states that require context saving upon entry: __cpu_suspend(unsigned long arg, int (*fn)(unsigned long)) __cpu_suspend() saves the context on function entry and calls the so called suspend finisher (ie fn) to complete the suspend operation. The finisher is not expected to return, unless it fails in which case the error is propagated back to the __cpu_suspend caller. The API refactoring results in the following pseudo code call sequence for a suspending CPU, when triggered from a kernel subsystem: /* * int cpu_suspend(unsigned long idx) * @idx: idle state index */ { -> cpu_suspend(idx) |---> CPU operations suspend hook called, if present |--> if (retention_state) |--> direct suspend back-end call (eg PSCI suspend) else |--> __cpu_suspend(idx, &back_end_finisher); } By refactoring the cpu_suspend API this way, the CPU operations back-end has a chance to detect whether idle states require state saving or not and can call the required suspend operations accordingly either through simple function call or indirectly through __cpu_suspend() which carries out state saving and suspend finisher dispatching to complete idle state entry. Reviewed-by: Catalin Marinas <catalin.marinas@arm.com> Reviewed-by: Hanjun Guo <hanjun.guo@linaro.org> Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2014-08-07 21:54:50 +08:00
ENTRY(__cpu_suspend_enter)
arm64: kernel: cpu_{suspend/resume} implementation Kernel subsystems like CPU idle and suspend to RAM require a generic mechanism to suspend a processor, save its context and put it into a quiescent state. The cpu_{suspend}/{resume} implementation provides such a framework through a kernel interface allowing to save/restore registers, flush the context to DRAM and suspend/resume to/from low-power states where processor context may be lost. The CPU suspend implementation relies on the suspend protocol registered in CPU operations to carry out a suspend request after context is saved and flushed to DRAM. The cpu_suspend interface: int cpu_suspend(unsigned long arg); allows to pass an opaque parameter that is handed over to the suspend CPU operations back-end so that it can take action according to the semantics attached to it. The arg parameter allows suspend to RAM and CPU idle drivers to communicate to suspend protocol back-ends; it requires standardization so that the interface can be reused seamlessly across systems, paving the way for generic drivers. Context memory is allocated on the stack, whose address is stashed in a per-cpu variable to keep track of it and passed to core functions that save/restore the registers required by the architecture. Even though, upon successful execution, the cpu_suspend function shuts down the suspending processor, the warm boot resume mechanism, based on the cpu_resume function, makes the resume path operate as a cpu_suspend function return, so that cpu_suspend can be treated as a C function by the caller, which simplifies coding the PM drivers that rely on the cpu_suspend API. Upon context save, the minimal amount of memory is flushed to DRAM so that it can be retrieved when the MMU is off and caches are not searched. The suspend CPU operation, depending on the required operations (eg CPU vs Cluster shutdown) is in charge of flushing the cache hierarchy either implicitly (by calling firmware implementations like PSCI) or explicitly by executing the required cache maintainance functions. Debug exceptions are disabled during cpu_{suspend}/{resume} operations so that debug registers can be saved and restored properly preventing preemption from debug agents enabled in the kernel. Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
2013-07-22 19:22:13 +08:00
stp x29, lr, [sp, #-96]!
stp x19, x20, [sp,#16]
stp x21, x22, [sp,#32]
stp x23, x24, [sp,#48]
stp x25, x26, [sp,#64]
stp x27, x28, [sp,#80]
arm64: kernel: refactor the CPU suspend API for retention states CPU suspend is the standard kernel interface to be used to enter low-power states on ARM64 systems. Current cpu_suspend implementation by default assumes that all low power states are losing the CPU context, so the CPU registers must be saved and cleaned to DRAM upon state entry. Furthermore, the current cpu_suspend() implementation assumes that if the CPU suspend back-end method returns when called, this has to be considered an error regardless of the return code (which can be successful) since the CPU was not expected to return from a code path that is different from cpu_resume code path - eg returning from the reset vector. All in all this means that the current API does not cope well with low-power states that preserve the CPU context when entered (ie retention states), since first of all the context is saved for nothing on state entry for those states and a successful state entry can return as a normal function return, which is considered an error by the current CPU suspend implementation. This patch refactors the cpu_suspend() API so that it can be split in two separate functionalities. The arm64 cpu_suspend API just provides a wrapper around CPU suspend operation hook. A new function is introduced (for architecture code use only) for states that require context saving upon entry: __cpu_suspend(unsigned long arg, int (*fn)(unsigned long)) __cpu_suspend() saves the context on function entry and calls the so called suspend finisher (ie fn) to complete the suspend operation. The finisher is not expected to return, unless it fails in which case the error is propagated back to the __cpu_suspend caller. The API refactoring results in the following pseudo code call sequence for a suspending CPU, when triggered from a kernel subsystem: /* * int cpu_suspend(unsigned long idx) * @idx: idle state index */ { -> cpu_suspend(idx) |---> CPU operations suspend hook called, if present |--> if (retention_state) |--> direct suspend back-end call (eg PSCI suspend) else |--> __cpu_suspend(idx, &back_end_finisher); } By refactoring the cpu_suspend API this way, the CPU operations back-end has a chance to detect whether idle states require state saving or not and can call the required suspend operations accordingly either through simple function call or indirectly through __cpu_suspend() which carries out state saving and suspend finisher dispatching to complete idle state entry. Reviewed-by: Catalin Marinas <catalin.marinas@arm.com> Reviewed-by: Hanjun Guo <hanjun.guo@linaro.org> Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2014-08-07 21:54:50 +08:00
/*
* Stash suspend finisher and its argument in x20 and x19
*/
mov x19, x0
mov x20, x1
arm64: kernel: cpu_{suspend/resume} implementation Kernel subsystems like CPU idle and suspend to RAM require a generic mechanism to suspend a processor, save its context and put it into a quiescent state. The cpu_{suspend}/{resume} implementation provides such a framework through a kernel interface allowing to save/restore registers, flush the context to DRAM and suspend/resume to/from low-power states where processor context may be lost. The CPU suspend implementation relies on the suspend protocol registered in CPU operations to carry out a suspend request after context is saved and flushed to DRAM. The cpu_suspend interface: int cpu_suspend(unsigned long arg); allows to pass an opaque parameter that is handed over to the suspend CPU operations back-end so that it can take action according to the semantics attached to it. The arg parameter allows suspend to RAM and CPU idle drivers to communicate to suspend protocol back-ends; it requires standardization so that the interface can be reused seamlessly across systems, paving the way for generic drivers. Context memory is allocated on the stack, whose address is stashed in a per-cpu variable to keep track of it and passed to core functions that save/restore the registers required by the architecture. Even though, upon successful execution, the cpu_suspend function shuts down the suspending processor, the warm boot resume mechanism, based on the cpu_resume function, makes the resume path operate as a cpu_suspend function return, so that cpu_suspend can be treated as a C function by the caller, which simplifies coding the PM drivers that rely on the cpu_suspend API. Upon context save, the minimal amount of memory is flushed to DRAM so that it can be retrieved when the MMU is off and caches are not searched. The suspend CPU operation, depending on the required operations (eg CPU vs Cluster shutdown) is in charge of flushing the cache hierarchy either implicitly (by calling firmware implementations like PSCI) or explicitly by executing the required cache maintainance functions. Debug exceptions are disabled during cpu_{suspend}/{resume} operations so that debug registers can be saved and restored properly preventing preemption from debug agents enabled in the kernel. Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
2013-07-22 19:22:13 +08:00
mov x2, sp
sub sp, sp, #CPU_SUSPEND_SZ // allocate cpu_suspend_ctx
arm64: kernel: refactor the CPU suspend API for retention states CPU suspend is the standard kernel interface to be used to enter low-power states on ARM64 systems. Current cpu_suspend implementation by default assumes that all low power states are losing the CPU context, so the CPU registers must be saved and cleaned to DRAM upon state entry. Furthermore, the current cpu_suspend() implementation assumes that if the CPU suspend back-end method returns when called, this has to be considered an error regardless of the return code (which can be successful) since the CPU was not expected to return from a code path that is different from cpu_resume code path - eg returning from the reset vector. All in all this means that the current API does not cope well with low-power states that preserve the CPU context when entered (ie retention states), since first of all the context is saved for nothing on state entry for those states and a successful state entry can return as a normal function return, which is considered an error by the current CPU suspend implementation. This patch refactors the cpu_suspend() API so that it can be split in two separate functionalities. The arm64 cpu_suspend API just provides a wrapper around CPU suspend operation hook. A new function is introduced (for architecture code use only) for states that require context saving upon entry: __cpu_suspend(unsigned long arg, int (*fn)(unsigned long)) __cpu_suspend() saves the context on function entry and calls the so called suspend finisher (ie fn) to complete the suspend operation. The finisher is not expected to return, unless it fails in which case the error is propagated back to the __cpu_suspend caller. The API refactoring results in the following pseudo code call sequence for a suspending CPU, when triggered from a kernel subsystem: /* * int cpu_suspend(unsigned long idx) * @idx: idle state index */ { -> cpu_suspend(idx) |---> CPU operations suspend hook called, if present |--> if (retention_state) |--> direct suspend back-end call (eg PSCI suspend) else |--> __cpu_suspend(idx, &back_end_finisher); } By refactoring the cpu_suspend API this way, the CPU operations back-end has a chance to detect whether idle states require state saving or not and can call the required suspend operations accordingly either through simple function call or indirectly through __cpu_suspend() which carries out state saving and suspend finisher dispatching to complete idle state entry. Reviewed-by: Catalin Marinas <catalin.marinas@arm.com> Reviewed-by: Hanjun Guo <hanjun.guo@linaro.org> Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2014-08-07 21:54:50 +08:00
mov x0, sp
arm64: kernel: cpu_{suspend/resume} implementation Kernel subsystems like CPU idle and suspend to RAM require a generic mechanism to suspend a processor, save its context and put it into a quiescent state. The cpu_{suspend}/{resume} implementation provides such a framework through a kernel interface allowing to save/restore registers, flush the context to DRAM and suspend/resume to/from low-power states where processor context may be lost. The CPU suspend implementation relies on the suspend protocol registered in CPU operations to carry out a suspend request after context is saved and flushed to DRAM. The cpu_suspend interface: int cpu_suspend(unsigned long arg); allows to pass an opaque parameter that is handed over to the suspend CPU operations back-end so that it can take action according to the semantics attached to it. The arg parameter allows suspend to RAM and CPU idle drivers to communicate to suspend protocol back-ends; it requires standardization so that the interface can be reused seamlessly across systems, paving the way for generic drivers. Context memory is allocated on the stack, whose address is stashed in a per-cpu variable to keep track of it and passed to core functions that save/restore the registers required by the architecture. Even though, upon successful execution, the cpu_suspend function shuts down the suspending processor, the warm boot resume mechanism, based on the cpu_resume function, makes the resume path operate as a cpu_suspend function return, so that cpu_suspend can be treated as a C function by the caller, which simplifies coding the PM drivers that rely on the cpu_suspend API. Upon context save, the minimal amount of memory is flushed to DRAM so that it can be retrieved when the MMU is off and caches are not searched. The suspend CPU operation, depending on the required operations (eg CPU vs Cluster shutdown) is in charge of flushing the cache hierarchy either implicitly (by calling firmware implementations like PSCI) or explicitly by executing the required cache maintainance functions. Debug exceptions are disabled during cpu_{suspend}/{resume} operations so that debug registers can be saved and restored properly preventing preemption from debug agents enabled in the kernel. Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
2013-07-22 19:22:13 +08:00
/*
arm64: kernel: refactor the CPU suspend API for retention states CPU suspend is the standard kernel interface to be used to enter low-power states on ARM64 systems. Current cpu_suspend implementation by default assumes that all low power states are losing the CPU context, so the CPU registers must be saved and cleaned to DRAM upon state entry. Furthermore, the current cpu_suspend() implementation assumes that if the CPU suspend back-end method returns when called, this has to be considered an error regardless of the return code (which can be successful) since the CPU was not expected to return from a code path that is different from cpu_resume code path - eg returning from the reset vector. All in all this means that the current API does not cope well with low-power states that preserve the CPU context when entered (ie retention states), since first of all the context is saved for nothing on state entry for those states and a successful state entry can return as a normal function return, which is considered an error by the current CPU suspend implementation. This patch refactors the cpu_suspend() API so that it can be split in two separate functionalities. The arm64 cpu_suspend API just provides a wrapper around CPU suspend operation hook. A new function is introduced (for architecture code use only) for states that require context saving upon entry: __cpu_suspend(unsigned long arg, int (*fn)(unsigned long)) __cpu_suspend() saves the context on function entry and calls the so called suspend finisher (ie fn) to complete the suspend operation. The finisher is not expected to return, unless it fails in which case the error is propagated back to the __cpu_suspend caller. The API refactoring results in the following pseudo code call sequence for a suspending CPU, when triggered from a kernel subsystem: /* * int cpu_suspend(unsigned long idx) * @idx: idle state index */ { -> cpu_suspend(idx) |---> CPU operations suspend hook called, if present |--> if (retention_state) |--> direct suspend back-end call (eg PSCI suspend) else |--> __cpu_suspend(idx, &back_end_finisher); } By refactoring the cpu_suspend API this way, the CPU operations back-end has a chance to detect whether idle states require state saving or not and can call the required suspend operations accordingly either through simple function call or indirectly through __cpu_suspend() which carries out state saving and suspend finisher dispatching to complete idle state entry. Reviewed-by: Catalin Marinas <catalin.marinas@arm.com> Reviewed-by: Hanjun Guo <hanjun.guo@linaro.org> Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2014-08-07 21:54:50 +08:00
* x0 now points to struct cpu_suspend_ctx allocated on the stack
arm64: kernel: cpu_{suspend/resume} implementation Kernel subsystems like CPU idle and suspend to RAM require a generic mechanism to suspend a processor, save its context and put it into a quiescent state. The cpu_{suspend}/{resume} implementation provides such a framework through a kernel interface allowing to save/restore registers, flush the context to DRAM and suspend/resume to/from low-power states where processor context may be lost. The CPU suspend implementation relies on the suspend protocol registered in CPU operations to carry out a suspend request after context is saved and flushed to DRAM. The cpu_suspend interface: int cpu_suspend(unsigned long arg); allows to pass an opaque parameter that is handed over to the suspend CPU operations back-end so that it can take action according to the semantics attached to it. The arg parameter allows suspend to RAM and CPU idle drivers to communicate to suspend protocol back-ends; it requires standardization so that the interface can be reused seamlessly across systems, paving the way for generic drivers. Context memory is allocated on the stack, whose address is stashed in a per-cpu variable to keep track of it and passed to core functions that save/restore the registers required by the architecture. Even though, upon successful execution, the cpu_suspend function shuts down the suspending processor, the warm boot resume mechanism, based on the cpu_resume function, makes the resume path operate as a cpu_suspend function return, so that cpu_suspend can be treated as a C function by the caller, which simplifies coding the PM drivers that rely on the cpu_suspend API. Upon context save, the minimal amount of memory is flushed to DRAM so that it can be retrieved when the MMU is off and caches are not searched. The suspend CPU operation, depending on the required operations (eg CPU vs Cluster shutdown) is in charge of flushing the cache hierarchy either implicitly (by calling firmware implementations like PSCI) or explicitly by executing the required cache maintainance functions. Debug exceptions are disabled during cpu_{suspend}/{resume} operations so that debug registers can be saved and restored properly preventing preemption from debug agents enabled in the kernel. Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
2013-07-22 19:22:13 +08:00
*/
arm64: kernel: refactor the CPU suspend API for retention states CPU suspend is the standard kernel interface to be used to enter low-power states on ARM64 systems. Current cpu_suspend implementation by default assumes that all low power states are losing the CPU context, so the CPU registers must be saved and cleaned to DRAM upon state entry. Furthermore, the current cpu_suspend() implementation assumes that if the CPU suspend back-end method returns when called, this has to be considered an error regardless of the return code (which can be successful) since the CPU was not expected to return from a code path that is different from cpu_resume code path - eg returning from the reset vector. All in all this means that the current API does not cope well with low-power states that preserve the CPU context when entered (ie retention states), since first of all the context is saved for nothing on state entry for those states and a successful state entry can return as a normal function return, which is considered an error by the current CPU suspend implementation. This patch refactors the cpu_suspend() API so that it can be split in two separate functionalities. The arm64 cpu_suspend API just provides a wrapper around CPU suspend operation hook. A new function is introduced (for architecture code use only) for states that require context saving upon entry: __cpu_suspend(unsigned long arg, int (*fn)(unsigned long)) __cpu_suspend() saves the context on function entry and calls the so called suspend finisher (ie fn) to complete the suspend operation. The finisher is not expected to return, unless it fails in which case the error is propagated back to the __cpu_suspend caller. The API refactoring results in the following pseudo code call sequence for a suspending CPU, when triggered from a kernel subsystem: /* * int cpu_suspend(unsigned long idx) * @idx: idle state index */ { -> cpu_suspend(idx) |---> CPU operations suspend hook called, if present |--> if (retention_state) |--> direct suspend back-end call (eg PSCI suspend) else |--> __cpu_suspend(idx, &back_end_finisher); } By refactoring the cpu_suspend API this way, the CPU operations back-end has a chance to detect whether idle states require state saving or not and can call the required suspend operations accordingly either through simple function call or indirectly through __cpu_suspend() which carries out state saving and suspend finisher dispatching to complete idle state entry. Reviewed-by: Catalin Marinas <catalin.marinas@arm.com> Reviewed-by: Hanjun Guo <hanjun.guo@linaro.org> Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2014-08-07 21:54:50 +08:00
str x2, [x0, #CPU_CTX_SP]
ldr x1, =sleep_save_sp
ldr x1, [x1, #SLEEP_SAVE_SP_VIRT]
arm64: kernel: cpu_{suspend/resume} implementation Kernel subsystems like CPU idle and suspend to RAM require a generic mechanism to suspend a processor, save its context and put it into a quiescent state. The cpu_{suspend}/{resume} implementation provides such a framework through a kernel interface allowing to save/restore registers, flush the context to DRAM and suspend/resume to/from low-power states where processor context may be lost. The CPU suspend implementation relies on the suspend protocol registered in CPU operations to carry out a suspend request after context is saved and flushed to DRAM. The cpu_suspend interface: int cpu_suspend(unsigned long arg); allows to pass an opaque parameter that is handed over to the suspend CPU operations back-end so that it can take action according to the semantics attached to it. The arg parameter allows suspend to RAM and CPU idle drivers to communicate to suspend protocol back-ends; it requires standardization so that the interface can be reused seamlessly across systems, paving the way for generic drivers. Context memory is allocated on the stack, whose address is stashed in a per-cpu variable to keep track of it and passed to core functions that save/restore the registers required by the architecture. Even though, upon successful execution, the cpu_suspend function shuts down the suspending processor, the warm boot resume mechanism, based on the cpu_resume function, makes the resume path operate as a cpu_suspend function return, so that cpu_suspend can be treated as a C function by the caller, which simplifies coding the PM drivers that rely on the cpu_suspend API. Upon context save, the minimal amount of memory is flushed to DRAM so that it can be retrieved when the MMU is off and caches are not searched. The suspend CPU operation, depending on the required operations (eg CPU vs Cluster shutdown) is in charge of flushing the cache hierarchy either implicitly (by calling firmware implementations like PSCI) or explicitly by executing the required cache maintainance functions. Debug exceptions are disabled during cpu_{suspend}/{resume} operations so that debug registers can be saved and restored properly preventing preemption from debug agents enabled in the kernel. Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
2013-07-22 19:22:13 +08:00
mrs x7, mpidr_el1
ldr x9, =mpidr_hash
ldr x10, [x9, #MPIDR_HASH_MASK]
/*
* Following code relies on the struct mpidr_hash
* members size.
*/
ldp w3, w4, [x9, #MPIDR_HASH_SHIFTS]
ldp w5, w6, [x9, #(MPIDR_HASH_SHIFTS + 8)]
compute_mpidr_hash x8, x3, x4, x5, x6, x7, x10
arm64: kernel: refactor the CPU suspend API for retention states CPU suspend is the standard kernel interface to be used to enter low-power states on ARM64 systems. Current cpu_suspend implementation by default assumes that all low power states are losing the CPU context, so the CPU registers must be saved and cleaned to DRAM upon state entry. Furthermore, the current cpu_suspend() implementation assumes that if the CPU suspend back-end method returns when called, this has to be considered an error regardless of the return code (which can be successful) since the CPU was not expected to return from a code path that is different from cpu_resume code path - eg returning from the reset vector. All in all this means that the current API does not cope well with low-power states that preserve the CPU context when entered (ie retention states), since first of all the context is saved for nothing on state entry for those states and a successful state entry can return as a normal function return, which is considered an error by the current CPU suspend implementation. This patch refactors the cpu_suspend() API so that it can be split in two separate functionalities. The arm64 cpu_suspend API just provides a wrapper around CPU suspend operation hook. A new function is introduced (for architecture code use only) for states that require context saving upon entry: __cpu_suspend(unsigned long arg, int (*fn)(unsigned long)) __cpu_suspend() saves the context on function entry and calls the so called suspend finisher (ie fn) to complete the suspend operation. The finisher is not expected to return, unless it fails in which case the error is propagated back to the __cpu_suspend caller. The API refactoring results in the following pseudo code call sequence for a suspending CPU, when triggered from a kernel subsystem: /* * int cpu_suspend(unsigned long idx) * @idx: idle state index */ { -> cpu_suspend(idx) |---> CPU operations suspend hook called, if present |--> if (retention_state) |--> direct suspend back-end call (eg PSCI suspend) else |--> __cpu_suspend(idx, &back_end_finisher); } By refactoring the cpu_suspend API this way, the CPU operations back-end has a chance to detect whether idle states require state saving or not and can call the required suspend operations accordingly either through simple function call or indirectly through __cpu_suspend() which carries out state saving and suspend finisher dispatching to complete idle state entry. Reviewed-by: Catalin Marinas <catalin.marinas@arm.com> Reviewed-by: Hanjun Guo <hanjun.guo@linaro.org> Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2014-08-07 21:54:50 +08:00
add x1, x1, x8, lsl #3
bl __cpu_suspend_save
/*
* Grab suspend finisher in x20 and its argument in x19
*/
mov x0, x19
mov x1, x20
/*
* We are ready for power down, fire off the suspend finisher
* in x1, with argument in x0
*/
blr x1
arm64: kernel: cpu_{suspend/resume} implementation Kernel subsystems like CPU idle and suspend to RAM require a generic mechanism to suspend a processor, save its context and put it into a quiescent state. The cpu_{suspend}/{resume} implementation provides such a framework through a kernel interface allowing to save/restore registers, flush the context to DRAM and suspend/resume to/from low-power states where processor context may be lost. The CPU suspend implementation relies on the suspend protocol registered in CPU operations to carry out a suspend request after context is saved and flushed to DRAM. The cpu_suspend interface: int cpu_suspend(unsigned long arg); allows to pass an opaque parameter that is handed over to the suspend CPU operations back-end so that it can take action according to the semantics attached to it. The arg parameter allows suspend to RAM and CPU idle drivers to communicate to suspend protocol back-ends; it requires standardization so that the interface can be reused seamlessly across systems, paving the way for generic drivers. Context memory is allocated on the stack, whose address is stashed in a per-cpu variable to keep track of it and passed to core functions that save/restore the registers required by the architecture. Even though, upon successful execution, the cpu_suspend function shuts down the suspending processor, the warm boot resume mechanism, based on the cpu_resume function, makes the resume path operate as a cpu_suspend function return, so that cpu_suspend can be treated as a C function by the caller, which simplifies coding the PM drivers that rely on the cpu_suspend API. Upon context save, the minimal amount of memory is flushed to DRAM so that it can be retrieved when the MMU is off and caches are not searched. The suspend CPU operation, depending on the required operations (eg CPU vs Cluster shutdown) is in charge of flushing the cache hierarchy either implicitly (by calling firmware implementations like PSCI) or explicitly by executing the required cache maintainance functions. Debug exceptions are disabled during cpu_{suspend}/{resume} operations so that debug registers can be saved and restored properly preventing preemption from debug agents enabled in the kernel. Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
2013-07-22 19:22:13 +08:00
/*
arm64: kernel: refactor the CPU suspend API for retention states CPU suspend is the standard kernel interface to be used to enter low-power states on ARM64 systems. Current cpu_suspend implementation by default assumes that all low power states are losing the CPU context, so the CPU registers must be saved and cleaned to DRAM upon state entry. Furthermore, the current cpu_suspend() implementation assumes that if the CPU suspend back-end method returns when called, this has to be considered an error regardless of the return code (which can be successful) since the CPU was not expected to return from a code path that is different from cpu_resume code path - eg returning from the reset vector. All in all this means that the current API does not cope well with low-power states that preserve the CPU context when entered (ie retention states), since first of all the context is saved for nothing on state entry for those states and a successful state entry can return as a normal function return, which is considered an error by the current CPU suspend implementation. This patch refactors the cpu_suspend() API so that it can be split in two separate functionalities. The arm64 cpu_suspend API just provides a wrapper around CPU suspend operation hook. A new function is introduced (for architecture code use only) for states that require context saving upon entry: __cpu_suspend(unsigned long arg, int (*fn)(unsigned long)) __cpu_suspend() saves the context on function entry and calls the so called suspend finisher (ie fn) to complete the suspend operation. The finisher is not expected to return, unless it fails in which case the error is propagated back to the __cpu_suspend caller. The API refactoring results in the following pseudo code call sequence for a suspending CPU, when triggered from a kernel subsystem: /* * int cpu_suspend(unsigned long idx) * @idx: idle state index */ { -> cpu_suspend(idx) |---> CPU operations suspend hook called, if present |--> if (retention_state) |--> direct suspend back-end call (eg PSCI suspend) else |--> __cpu_suspend(idx, &back_end_finisher); } By refactoring the cpu_suspend API this way, the CPU operations back-end has a chance to detect whether idle states require state saving or not and can call the required suspend operations accordingly either through simple function call or indirectly through __cpu_suspend() which carries out state saving and suspend finisher dispatching to complete idle state entry. Reviewed-by: Catalin Marinas <catalin.marinas@arm.com> Reviewed-by: Hanjun Guo <hanjun.guo@linaro.org> Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2014-08-07 21:54:50 +08:00
* Never gets here, unless suspend finisher fails.
arm64: kernel: cpu_{suspend/resume} implementation Kernel subsystems like CPU idle and suspend to RAM require a generic mechanism to suspend a processor, save its context and put it into a quiescent state. The cpu_{suspend}/{resume} implementation provides such a framework through a kernel interface allowing to save/restore registers, flush the context to DRAM and suspend/resume to/from low-power states where processor context may be lost. The CPU suspend implementation relies on the suspend protocol registered in CPU operations to carry out a suspend request after context is saved and flushed to DRAM. The cpu_suspend interface: int cpu_suspend(unsigned long arg); allows to pass an opaque parameter that is handed over to the suspend CPU operations back-end so that it can take action according to the semantics attached to it. The arg parameter allows suspend to RAM and CPU idle drivers to communicate to suspend protocol back-ends; it requires standardization so that the interface can be reused seamlessly across systems, paving the way for generic drivers. Context memory is allocated on the stack, whose address is stashed in a per-cpu variable to keep track of it and passed to core functions that save/restore the registers required by the architecture. Even though, upon successful execution, the cpu_suspend function shuts down the suspending processor, the warm boot resume mechanism, based on the cpu_resume function, makes the resume path operate as a cpu_suspend function return, so that cpu_suspend can be treated as a C function by the caller, which simplifies coding the PM drivers that rely on the cpu_suspend API. Upon context save, the minimal amount of memory is flushed to DRAM so that it can be retrieved when the MMU is off and caches are not searched. The suspend CPU operation, depending on the required operations (eg CPU vs Cluster shutdown) is in charge of flushing the cache hierarchy either implicitly (by calling firmware implementations like PSCI) or explicitly by executing the required cache maintainance functions. Debug exceptions are disabled during cpu_{suspend}/{resume} operations so that debug registers can be saved and restored properly preventing preemption from debug agents enabled in the kernel. Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
2013-07-22 19:22:13 +08:00
* Successful cpu_suspend should return from cpu_resume, returning
* through this code path is considered an error
* If the return value is set to 0 force x0 = -EOPNOTSUPP
* to make sure a proper error condition is propagated
*/
cmp x0, #0
mov x3, #-EOPNOTSUPP
csel x0, x3, x0, eq
add sp, sp, #CPU_SUSPEND_SZ // rewind stack pointer
ldp x19, x20, [sp, #16]
ldp x21, x22, [sp, #32]
ldp x23, x24, [sp, #48]
ldp x25, x26, [sp, #64]
ldp x27, x28, [sp, #80]
ldp x29, lr, [sp], #96
ret
arm64: kernel: refactor the CPU suspend API for retention states CPU suspend is the standard kernel interface to be used to enter low-power states on ARM64 systems. Current cpu_suspend implementation by default assumes that all low power states are losing the CPU context, so the CPU registers must be saved and cleaned to DRAM upon state entry. Furthermore, the current cpu_suspend() implementation assumes that if the CPU suspend back-end method returns when called, this has to be considered an error regardless of the return code (which can be successful) since the CPU was not expected to return from a code path that is different from cpu_resume code path - eg returning from the reset vector. All in all this means that the current API does not cope well with low-power states that preserve the CPU context when entered (ie retention states), since first of all the context is saved for nothing on state entry for those states and a successful state entry can return as a normal function return, which is considered an error by the current CPU suspend implementation. This patch refactors the cpu_suspend() API so that it can be split in two separate functionalities. The arm64 cpu_suspend API just provides a wrapper around CPU suspend operation hook. A new function is introduced (for architecture code use only) for states that require context saving upon entry: __cpu_suspend(unsigned long arg, int (*fn)(unsigned long)) __cpu_suspend() saves the context on function entry and calls the so called suspend finisher (ie fn) to complete the suspend operation. The finisher is not expected to return, unless it fails in which case the error is propagated back to the __cpu_suspend caller. The API refactoring results in the following pseudo code call sequence for a suspending CPU, when triggered from a kernel subsystem: /* * int cpu_suspend(unsigned long idx) * @idx: idle state index */ { -> cpu_suspend(idx) |---> CPU operations suspend hook called, if present |--> if (retention_state) |--> direct suspend back-end call (eg PSCI suspend) else |--> __cpu_suspend(idx, &back_end_finisher); } By refactoring the cpu_suspend API this way, the CPU operations back-end has a chance to detect whether idle states require state saving or not and can call the required suspend operations accordingly either through simple function call or indirectly through __cpu_suspend() which carries out state saving and suspend finisher dispatching to complete idle state entry. Reviewed-by: Catalin Marinas <catalin.marinas@arm.com> Reviewed-by: Hanjun Guo <hanjun.guo@linaro.org> Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2014-08-07 21:54:50 +08:00
ENDPROC(__cpu_suspend_enter)
arm64: kernel: cpu_{suspend/resume} implementation Kernel subsystems like CPU idle and suspend to RAM require a generic mechanism to suspend a processor, save its context and put it into a quiescent state. The cpu_{suspend}/{resume} implementation provides such a framework through a kernel interface allowing to save/restore registers, flush the context to DRAM and suspend/resume to/from low-power states where processor context may be lost. The CPU suspend implementation relies on the suspend protocol registered in CPU operations to carry out a suspend request after context is saved and flushed to DRAM. The cpu_suspend interface: int cpu_suspend(unsigned long arg); allows to pass an opaque parameter that is handed over to the suspend CPU operations back-end so that it can take action according to the semantics attached to it. The arg parameter allows suspend to RAM and CPU idle drivers to communicate to suspend protocol back-ends; it requires standardization so that the interface can be reused seamlessly across systems, paving the way for generic drivers. Context memory is allocated on the stack, whose address is stashed in a per-cpu variable to keep track of it and passed to core functions that save/restore the registers required by the architecture. Even though, upon successful execution, the cpu_suspend function shuts down the suspending processor, the warm boot resume mechanism, based on the cpu_resume function, makes the resume path operate as a cpu_suspend function return, so that cpu_suspend can be treated as a C function by the caller, which simplifies coding the PM drivers that rely on the cpu_suspend API. Upon context save, the minimal amount of memory is flushed to DRAM so that it can be retrieved when the MMU is off and caches are not searched. The suspend CPU operation, depending on the required operations (eg CPU vs Cluster shutdown) is in charge of flushing the cache hierarchy either implicitly (by calling firmware implementations like PSCI) or explicitly by executing the required cache maintainance functions. Debug exceptions are disabled during cpu_{suspend}/{resume} operations so that debug registers can be saved and restored properly preventing preemption from debug agents enabled in the kernel. Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
2013-07-22 19:22:13 +08:00
.ltorg
/*
* x0 must contain the sctlr value retrieved from restored context
*/
.pushsection ".idmap.text", "ax"
arm64: kernel: cpu_{suspend/resume} implementation Kernel subsystems like CPU idle and suspend to RAM require a generic mechanism to suspend a processor, save its context and put it into a quiescent state. The cpu_{suspend}/{resume} implementation provides such a framework through a kernel interface allowing to save/restore registers, flush the context to DRAM and suspend/resume to/from low-power states where processor context may be lost. The CPU suspend implementation relies on the suspend protocol registered in CPU operations to carry out a suspend request after context is saved and flushed to DRAM. The cpu_suspend interface: int cpu_suspend(unsigned long arg); allows to pass an opaque parameter that is handed over to the suspend CPU operations back-end so that it can take action according to the semantics attached to it. The arg parameter allows suspend to RAM and CPU idle drivers to communicate to suspend protocol back-ends; it requires standardization so that the interface can be reused seamlessly across systems, paving the way for generic drivers. Context memory is allocated on the stack, whose address is stashed in a per-cpu variable to keep track of it and passed to core functions that save/restore the registers required by the architecture. Even though, upon successful execution, the cpu_suspend function shuts down the suspending processor, the warm boot resume mechanism, based on the cpu_resume function, makes the resume path operate as a cpu_suspend function return, so that cpu_suspend can be treated as a C function by the caller, which simplifies coding the PM drivers that rely on the cpu_suspend API. Upon context save, the minimal amount of memory is flushed to DRAM so that it can be retrieved when the MMU is off and caches are not searched. The suspend CPU operation, depending on the required operations (eg CPU vs Cluster shutdown) is in charge of flushing the cache hierarchy either implicitly (by calling firmware implementations like PSCI) or explicitly by executing the required cache maintainance functions. Debug exceptions are disabled during cpu_{suspend}/{resume} operations so that debug registers can be saved and restored properly preventing preemption from debug agents enabled in the kernel. Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
2013-07-22 19:22:13 +08:00
ENTRY(cpu_resume_mmu)
ldr x3, =cpu_resume_after_mmu
msr sctlr_el1, x0 // restore sctlr_el1
isb
/*
* Invalidate the local I-cache so that any instructions fetched
* speculatively from the PoC are discarded, since they may have
* been dynamically patched at the PoU.
*/
ic iallu
dsb nsh
isb
arm64: kernel: cpu_{suspend/resume} implementation Kernel subsystems like CPU idle and suspend to RAM require a generic mechanism to suspend a processor, save its context and put it into a quiescent state. The cpu_{suspend}/{resume} implementation provides such a framework through a kernel interface allowing to save/restore registers, flush the context to DRAM and suspend/resume to/from low-power states where processor context may be lost. The CPU suspend implementation relies on the suspend protocol registered in CPU operations to carry out a suspend request after context is saved and flushed to DRAM. The cpu_suspend interface: int cpu_suspend(unsigned long arg); allows to pass an opaque parameter that is handed over to the suspend CPU operations back-end so that it can take action according to the semantics attached to it. The arg parameter allows suspend to RAM and CPU idle drivers to communicate to suspend protocol back-ends; it requires standardization so that the interface can be reused seamlessly across systems, paving the way for generic drivers. Context memory is allocated on the stack, whose address is stashed in a per-cpu variable to keep track of it and passed to core functions that save/restore the registers required by the architecture. Even though, upon successful execution, the cpu_suspend function shuts down the suspending processor, the warm boot resume mechanism, based on the cpu_resume function, makes the resume path operate as a cpu_suspend function return, so that cpu_suspend can be treated as a C function by the caller, which simplifies coding the PM drivers that rely on the cpu_suspend API. Upon context save, the minimal amount of memory is flushed to DRAM so that it can be retrieved when the MMU is off and caches are not searched. The suspend CPU operation, depending on the required operations (eg CPU vs Cluster shutdown) is in charge of flushing the cache hierarchy either implicitly (by calling firmware implementations like PSCI) or explicitly by executing the required cache maintainance functions. Debug exceptions are disabled during cpu_{suspend}/{resume} operations so that debug registers can be saved and restored properly preventing preemption from debug agents enabled in the kernel. Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
2013-07-22 19:22:13 +08:00
br x3 // global jump to virtual address
ENDPROC(cpu_resume_mmu)
.popsection
arm64: kernel: cpu_{suspend/resume} implementation Kernel subsystems like CPU idle and suspend to RAM require a generic mechanism to suspend a processor, save its context and put it into a quiescent state. The cpu_{suspend}/{resume} implementation provides such a framework through a kernel interface allowing to save/restore registers, flush the context to DRAM and suspend/resume to/from low-power states where processor context may be lost. The CPU suspend implementation relies on the suspend protocol registered in CPU operations to carry out a suspend request after context is saved and flushed to DRAM. The cpu_suspend interface: int cpu_suspend(unsigned long arg); allows to pass an opaque parameter that is handed over to the suspend CPU operations back-end so that it can take action according to the semantics attached to it. The arg parameter allows suspend to RAM and CPU idle drivers to communicate to suspend protocol back-ends; it requires standardization so that the interface can be reused seamlessly across systems, paving the way for generic drivers. Context memory is allocated on the stack, whose address is stashed in a per-cpu variable to keep track of it and passed to core functions that save/restore the registers required by the architecture. Even though, upon successful execution, the cpu_suspend function shuts down the suspending processor, the warm boot resume mechanism, based on the cpu_resume function, makes the resume path operate as a cpu_suspend function return, so that cpu_suspend can be treated as a C function by the caller, which simplifies coding the PM drivers that rely on the cpu_suspend API. Upon context save, the minimal amount of memory is flushed to DRAM so that it can be retrieved when the MMU is off and caches are not searched. The suspend CPU operation, depending on the required operations (eg CPU vs Cluster shutdown) is in charge of flushing the cache hierarchy either implicitly (by calling firmware implementations like PSCI) or explicitly by executing the required cache maintainance functions. Debug exceptions are disabled during cpu_{suspend}/{resume} operations so that debug registers can be saved and restored properly preventing preemption from debug agents enabled in the kernel. Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
2013-07-22 19:22:13 +08:00
cpu_resume_after_mmu:
mov x0, #0 // return zero on success
ldp x19, x20, [sp, #16]
ldp x21, x22, [sp, #32]
ldp x23, x24, [sp, #48]
ldp x25, x26, [sp, #64]
ldp x27, x28, [sp, #80]
ldp x29, lr, [sp], #96
ret
ENDPROC(cpu_resume_after_mmu)
ENTRY(cpu_resume)
bl el2_setup // if in EL2 drop to EL1 cleanly
mrs x1, mpidr_el1
adrp x8, mpidr_hash
add x8, x8, #:lo12:mpidr_hash // x8 = struct mpidr_hash phys address
arm64: kernel: cpu_{suspend/resume} implementation Kernel subsystems like CPU idle and suspend to RAM require a generic mechanism to suspend a processor, save its context and put it into a quiescent state. The cpu_{suspend}/{resume} implementation provides such a framework through a kernel interface allowing to save/restore registers, flush the context to DRAM and suspend/resume to/from low-power states where processor context may be lost. The CPU suspend implementation relies on the suspend protocol registered in CPU operations to carry out a suspend request after context is saved and flushed to DRAM. The cpu_suspend interface: int cpu_suspend(unsigned long arg); allows to pass an opaque parameter that is handed over to the suspend CPU operations back-end so that it can take action according to the semantics attached to it. The arg parameter allows suspend to RAM and CPU idle drivers to communicate to suspend protocol back-ends; it requires standardization so that the interface can be reused seamlessly across systems, paving the way for generic drivers. Context memory is allocated on the stack, whose address is stashed in a per-cpu variable to keep track of it and passed to core functions that save/restore the registers required by the architecture. Even though, upon successful execution, the cpu_suspend function shuts down the suspending processor, the warm boot resume mechanism, based on the cpu_resume function, makes the resume path operate as a cpu_suspend function return, so that cpu_suspend can be treated as a C function by the caller, which simplifies coding the PM drivers that rely on the cpu_suspend API. Upon context save, the minimal amount of memory is flushed to DRAM so that it can be retrieved when the MMU is off and caches are not searched. The suspend CPU operation, depending on the required operations (eg CPU vs Cluster shutdown) is in charge of flushing the cache hierarchy either implicitly (by calling firmware implementations like PSCI) or explicitly by executing the required cache maintainance functions. Debug exceptions are disabled during cpu_{suspend}/{resume} operations so that debug registers can be saved and restored properly preventing preemption from debug agents enabled in the kernel. Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
2013-07-22 19:22:13 +08:00
/* retrieve mpidr_hash members to compute the hash */
ldr x2, [x8, #MPIDR_HASH_MASK]
ldp w3, w4, [x8, #MPIDR_HASH_SHIFTS]
ldp w5, w6, [x8, #(MPIDR_HASH_SHIFTS + 8)]
compute_mpidr_hash x7, x3, x4, x5, x6, x1, x2
/* x7 contains hash index, let's use it to grab context pointer */
ldr_l x0, sleep_save_sp + SLEEP_SAVE_SP_PHYS
arm64: kernel: cpu_{suspend/resume} implementation Kernel subsystems like CPU idle and suspend to RAM require a generic mechanism to suspend a processor, save its context and put it into a quiescent state. The cpu_{suspend}/{resume} implementation provides such a framework through a kernel interface allowing to save/restore registers, flush the context to DRAM and suspend/resume to/from low-power states where processor context may be lost. The CPU suspend implementation relies on the suspend protocol registered in CPU operations to carry out a suspend request after context is saved and flushed to DRAM. The cpu_suspend interface: int cpu_suspend(unsigned long arg); allows to pass an opaque parameter that is handed over to the suspend CPU operations back-end so that it can take action according to the semantics attached to it. The arg parameter allows suspend to RAM and CPU idle drivers to communicate to suspend protocol back-ends; it requires standardization so that the interface can be reused seamlessly across systems, paving the way for generic drivers. Context memory is allocated on the stack, whose address is stashed in a per-cpu variable to keep track of it and passed to core functions that save/restore the registers required by the architecture. Even though, upon successful execution, the cpu_suspend function shuts down the suspending processor, the warm boot resume mechanism, based on the cpu_resume function, makes the resume path operate as a cpu_suspend function return, so that cpu_suspend can be treated as a C function by the caller, which simplifies coding the PM drivers that rely on the cpu_suspend API. Upon context save, the minimal amount of memory is flushed to DRAM so that it can be retrieved when the MMU is off and caches are not searched. The suspend CPU operation, depending on the required operations (eg CPU vs Cluster shutdown) is in charge of flushing the cache hierarchy either implicitly (by calling firmware implementations like PSCI) or explicitly by executing the required cache maintainance functions. Debug exceptions are disabled during cpu_{suspend}/{resume} operations so that debug registers can be saved and restored properly preventing preemption from debug agents enabled in the kernel. Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
2013-07-22 19:22:13 +08:00
ldr x0, [x0, x7, lsl #3]
/* load sp from context */
ldr x2, [x0, #CPU_CTX_SP]
/* load physical address of identity map page table in x1 */
adrp x1, idmap_pg_dir
arm64: kernel: cpu_{suspend/resume} implementation Kernel subsystems like CPU idle and suspend to RAM require a generic mechanism to suspend a processor, save its context and put it into a quiescent state. The cpu_{suspend}/{resume} implementation provides such a framework through a kernel interface allowing to save/restore registers, flush the context to DRAM and suspend/resume to/from low-power states where processor context may be lost. The CPU suspend implementation relies on the suspend protocol registered in CPU operations to carry out a suspend request after context is saved and flushed to DRAM. The cpu_suspend interface: int cpu_suspend(unsigned long arg); allows to pass an opaque parameter that is handed over to the suspend CPU operations back-end so that it can take action according to the semantics attached to it. The arg parameter allows suspend to RAM and CPU idle drivers to communicate to suspend protocol back-ends; it requires standardization so that the interface can be reused seamlessly across systems, paving the way for generic drivers. Context memory is allocated on the stack, whose address is stashed in a per-cpu variable to keep track of it and passed to core functions that save/restore the registers required by the architecture. Even though, upon successful execution, the cpu_suspend function shuts down the suspending processor, the warm boot resume mechanism, based on the cpu_resume function, makes the resume path operate as a cpu_suspend function return, so that cpu_suspend can be treated as a C function by the caller, which simplifies coding the PM drivers that rely on the cpu_suspend API. Upon context save, the minimal amount of memory is flushed to DRAM so that it can be retrieved when the MMU is off and caches are not searched. The suspend CPU operation, depending on the required operations (eg CPU vs Cluster shutdown) is in charge of flushing the cache hierarchy either implicitly (by calling firmware implementations like PSCI) or explicitly by executing the required cache maintainance functions. Debug exceptions are disabled during cpu_{suspend}/{resume} operations so that debug registers can be saved and restored properly preventing preemption from debug agents enabled in the kernel. Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
2013-07-22 19:22:13 +08:00
mov sp, x2
/*
* cpu_do_resume expects x0 to contain context physical address
* pointer and x1 to contain physical address of 1:1 page tables
*/
bl cpu_do_resume // PC relative jump, MMU off
b cpu_resume_mmu // Resume MMU, never returns
ENDPROC(cpu_resume)