Re: [PATCH V5 2/3] soc: qcom: boot_stat: Add Driver Support for Boot Stats

Souradeep Chowdhury
2023-04-21T10:23:08Z

On 4/21/2023 3:32 PM, Bryan O'Donoghue wrote:
> On 18/04/2023 07:46, Souradeep Chowdhury wrote:
>> All of Qualcomm's proprietary Android boot-loaders capture boot time
>> stats, like the time when the bootloader started execution and at what
>> point the bootloader handed over control to the kernel etc. in the IMEM
>> region. This information is captured in a specific format by this driver
>> by mapping a structure to the IMEM memory region and then accessing the
>> members of the structure to show the information within debugfs file.
>> This information is useful in verifying if the existing boot KPIs have
>> regressed or not. The information is shown in milliseconds, a sample
>> log from sm8450(waipio) device is as follows:-
>>
>> /sys/kernel/debug/146aa6b0.boot_stats # cat abl_time
>> 17898 ms
>> /sys/kernel/debug/146aa6b0.boot_stats # cat pre_abl_time
>> 2879 ms
>>
>> The Module Power Manager(MPM) sleep counter starts ticking at the PBL
>> stage and the timestamp generated by the sleep counter is logged by
>> the Qualcomm proprietary bootloader(ABL) at two points-> First when it
>> starts execution which is logged here as "pre_abl_time" and the second
>> when it is about to load the kernel logged as "abl_time". Documentation
>> details are also added in
>> Documentation/ABI/testing/debugfs-driver-bootstat
>>
>> Signed-off-by: Souradeep Chowdhury <quic_schowdhu@quicinc.com>
>> ---
>>   Documentation/ABI/testing/debugfs-driver-bootstat |  17 ++++
>>   drivers/soc/qcom/Kconfig                          |   9 ++
>>   drivers/soc/qcom/Makefile                         |   1 +
>>   drivers/soc/qcom/boot_stats.c                     | 101
>> ++++++++++++++++++++++
>>   4 files changed, 128 insertions(+)
>>   create mode 100644 Documentation/ABI/testing/debugfs-driver-bootstat
>>   create mode 100644 drivers/soc/qcom/boot_stats.c
>>
>> diff --git a/Documentation/ABI/testing/debugfs-driver-bootstat
>> b/Documentation/ABI/testing/debugfs-driver-bootstat
>> new file mode 100644
>> index 0000000..2543029
>> --- /dev/null
>> +++ b/Documentation/ABI/testing/debugfs-driver-bootstat
>> @@ -0,0 +1,17 @@
>> +What:        /sys/kernel/debug/...stats/pre_abl_time
>> +Date:           April 2023
>> +Contact:        Souradeep Chowdhury <quic_schowdhu@quicinc.com>
>> +Description:
>> +        This file is used to read the KPI value pre abl time.
>> +        It shows the time in milliseconds from the starting
>> +        point of PBL to the point when the control shifted
>> +        to ABL(Qualcomm proprietary bootloader).
>> +
>> +What:           /sys/kernel/debug/...stats/abl_time
>> +Date:           April 2023
>> +Contact:        Souradeep Chowdhury <quic_schowdhu@quicinc.com>
>> +Description:
>> +        This file is used to read the KPI value abl time.
>> +        It show the duration in milliseconds from the
>> +        time control switched to ABL to the point when
>> +        the linux kernel started getting loaded.
>> diff --git a/drivers/soc/qcom/Kconfig b/drivers/soc/qcom/Kconfig
>> index a8f2830..0d2cbd3 100644
>> --- a/drivers/soc/qcom/Kconfig
>> +++ b/drivers/soc/qcom/Kconfig
>> @@ -16,6 +16,15 @@ config QCOM_AOSS_QMP
>>         subsystems as well as controlling the debug clocks exposed by
>> the Always On
>>         Subsystem (AOSS) using Qualcomm Messaging Protocol (QMP).
>> +config QCOM_BOOTSTAT
>> +    tristate "Qualcomm Technologies, Boot Stat driver"
>> +    depends on ARCH_QCOM || COMPILE_TEST
>> +    help
>> +      This option enables driver support for boot stats. Boot stat
>> driver logs
>> +      the kernel bootloader information by accessing the imem region.
>> These
>> +      information are exposed in the form of debugfs files. This is
>> used to
>> +      determine if there is any regression in boot timings.
>> +
>>   config QCOM_COMMAND_DB
>>       tristate "Qualcomm Command DB"
>>       depends on ARCH_QCOM || COMPILE_TEST
>> diff --git a/drivers/soc/qcom/Makefile b/drivers/soc/qcom/Makefile
>> index 6e88da8..bdaa41a 100644
>> --- a/drivers/soc/qcom/Makefile
>> +++ b/drivers/soc/qcom/Makefile
>> @@ -1,6 +1,7 @@
>>   # SPDX-License-Identifier: GPL-2.0
>>   CFLAGS_rpmh-rsc.o := -I$(src)
>>   obj-$(CONFIG_QCOM_AOSS_QMP) +=    qcom_aoss.o
>> +obj-$(CONFIG_QCOM_BOOTSTAT) += boot_stats.o
>>   obj-$(CONFIG_QCOM_GENI_SE) +=    qcom-geni-se.o
>>   obj-$(CONFIG_QCOM_COMMAND_DB) += cmd-db.o
>>   obj-$(CONFIG_QCOM_CPR)        += cpr.o
>> diff --git a/drivers/soc/qcom/boot_stats.c
>> b/drivers/soc/qcom/boot_stats.c
>> new file mode 100644
>> index 0000000..7ae002b
>> --- /dev/null
>> +++ b/drivers/soc/qcom/boot_stats.c
>> @@ -0,0 +1,101 @@
>> +// SPDX-License-Identifier: GPL-2.0-only
>> +/*
>> + * Copyright (c) 2013-2019, 2021 The Linux Foundation. All rights
>> reserved.
>> + * Copyright (c) 2023 Qualcomm Innovation Center, Inc. All rights
>> reserved.
>> + */
>> +
>> +#include <linux/debugfs.h>
>> +#include <linux/err.h>
>> +#include <linux/io.h>
>> +#include <linux/init.h>
>> +#include <linux/kernel.h>
>> +#include <linux/module.h>
>> +#include <linux/of.h>
>> +#include <linux/of_address.h>
>> +#include <linux/platform_device.h>
>> +
>> +#define TO_MS(timestamp) ((timestamp * 1000) / 32768)
>
> Is this related to the sleep_clk, if not, what is the refrence clock ?
>
> Is this value constant across different SoCs i.e. will this run and
> produce meaningful results on an msm8916 ?

This is the sleep counter of MPM(Module Power Manager), yes, it will
produce meaningful results on almost all QCOM SoCs including msm8916.

>
> ---
> bod