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

Bryan O'Donoghue
2023-04-21T10:02:37Z

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 ?

---
bod