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

[Souradeep Chowdhury]

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@xxxxxxxxxxx>
> > ---
> >   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@xxxxxxxxxxx>
> > +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@xxxxxxxxxxx>
> > +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