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SubjectRe: [RFC 07/11] coresight: sink: Add TRBE driver
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On 11/14/20 11:08 AM, Tingwei Zhang wrote:
> Hi Anshuman,
>
> On Tue, Nov 10, 2020 at 08:45:05PM +0800, Anshuman Khandual wrote:
>> Trace Buffer Extension (TRBE) implements a trace buffer per CPU which is
>> accessible via the system registers. The TRBE supports different addressing
>> modes including CPU virtual address and buffer modes including the circular
>> buffer mode. The TRBE buffer is addressed by a base pointer (TRBBASER_EL1),
>> an write pointer (TRBPTR_EL1) and a limit pointer (TRBLIMITR_EL1). But the
>> access to the trace buffer could be prohibited by a higher exception level
>> (EL3 or EL2), indicated by TRBIDR_EL1.P. The TRBE can also generate a CPU
>> private interrupt (PPI) on address translation errors and when the buffer
>> is full. Overall implementation here is inspired from the Arm SPE driver.
>>
>> Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
>> ---
>> Documentation/trace/coresight/coresight-trbe.rst | 36 ++
>> arch/arm64/include/asm/sysreg.h | 2 +
>> drivers/hwtracing/coresight/Kconfig | 11 +
>> drivers/hwtracing/coresight/Makefile | 1 +
>> drivers/hwtracing/coresight/coresight-trbe.c | 766
>> +++++++++++++++++++++++
>> drivers/hwtracing/coresight/coresight-trbe.h | 525 ++++++++++++++++
>> 6 files changed, 1341 insertions(+)
>> create mode 100644 Documentation/trace/coresight/coresight-trbe.rst
>> create mode 100644 drivers/hwtracing/coresight/coresight-trbe.c
>> create mode 100644 drivers/hwtracing/coresight/coresight-trbe.h
>>
>> diff --git a/Documentation/trace/coresight/coresight-trbe.rst
>> b/Documentation/trace/coresight/coresight-trbe.rst
>> new file mode 100644
>> index 0000000..4320a8b
>> --- /dev/null
>> +++ b/Documentation/trace/coresight/coresight-trbe.rst
>> @@ -0,0 +1,36 @@
>> +.. SPDX-License-Identifier: GPL-2.0
>> +
>> +==============================
>> +Trace Buffer Extension (TRBE).
>> +==============================
>> +
>> + :Author: Anshuman Khandual <anshuman.khandual@arm.com>
>> + :Date: November 2020
>> +
>> +Hardware Description
>> +--------------------
>> +
>> +Trace Buffer Extension (TRBE) is a percpu hardware which captures in system
>> +memory, CPU traces generated from a corresponding percpu tracing unit. This
>> +gets plugged in as a coresight sink device because the corresponding trace
>> +genarators (ETE), are plugged in as source device.
>> +
>> +Sysfs files and directories
>> +---------------------------
>> +
>> +The TRBE devices appear on the existing coresight bus alongside the other
>> +coresight devices::
>> +
>> + >$ ls /sys/bus/coresight/devices
>> + trbe0 trbe1 trbe2 trbe3
>> +
>> +The ``trbe<N>`` named TRBEs are associated with a CPU.::
>> +
>> + >$ ls /sys/bus/coresight/devices/trbe0/
>> + irq align dbm
>> +
>> +*Key file items are:-*
>> + * ``irq``: TRBE maintenance interrupt number
>> + * ``align``: TRBE write pointer alignment
>> + * ``dbm``: TRBE updates memory with access and dirty flags
>> +
>> diff --git a/arch/arm64/include/asm/sysreg.h
>> b/arch/arm64/include/asm/sysreg.h
>> index 14cb156..61136f6 100644
>> --- a/arch/arm64/include/asm/sysreg.h
>> +++ b/arch/arm64/include/asm/sysreg.h
>> @@ -97,6 +97,7 @@
>> #define SET_PSTATE_UAO(x) __emit_inst(0xd500401f | PSTATE_UAO | ((!!x) <<
>> PSTATE_Imm_shift))
>> #define SET_PSTATE_SSBS(x) __emit_inst(0xd500401f | PSTATE_SSBS | ((!!x)
>> << PSTATE_Imm_shift))
>> #define SET_PSTATE_TCO(x) __emit_inst(0xd500401f | PSTATE_TCO | ((!!x) <<
>> PSTATE_Imm_shift))
>> +#define TSB_CSYNC __emit_inst(0xd503225f)
>>
>> #define __SYS_BARRIER_INSN(CRm, op2, Rt) \
>> __emit_inst(0xd5000000 | sys_insn(0, 3, 3, (CRm), (op2)) | ((Rt) & 0x1f))
>> @@ -865,6 +866,7 @@
>> #define ID_AA64MMFR2_CNP_SHIFT 0
>>
>> /* id_aa64dfr0 */
>> +#define ID_AA64DFR0_TRBE_SHIFT 44
>> #define ID_AA64DFR0_TRACE_FILT_SHIFT 40
>> #define ID_AA64DFR0_DOUBLELOCK_SHIFT 36
>> #define ID_AA64DFR0_PMSVER_SHIFT 32
>> diff --git a/drivers/hwtracing/coresight/Kconfig
>> b/drivers/hwtracing/coresight/Kconfig
>> index c119824..0f5e101 100644
>> --- a/drivers/hwtracing/coresight/Kconfig
>> +++ b/drivers/hwtracing/coresight/Kconfig
>> @@ -156,6 +156,17 @@ config CORESIGHT_CTI
>> To compile this driver as a module, choose M here: the
>> module will be called coresight-cti.
>>
>> +config CORESIGHT_TRBE
>> + bool "Trace Buffer Extension (TRBE) driver"
>
> Can you consider to support TRBE as loadable module since all coresight
> drivers support loadable module now.

Reworking the TRBE driver and making it a loadable module is part of it.

- Anshuman

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