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Message-ID: <b66290c6-5c1b-70a4-84e3-d65b139d1460@nexus-software.ie>
Date:   Fri, 21 Apr 2023 11:02:24 +0100
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Subject: Re: [PATCH V5 2/3] soc: qcom: boot_stat: Add Driver Support for Boot
 Stats
To:     Souradeep Chowdhury <quic_schowdhu@quicinc.com>,
        Andy Gross <agross@kernel.org>,
        Konrad Dybcio <konrad.dybcio@somainline.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
        Bjorn Andersson <andersson@kernel.org>,
        Rob Herring <robh+dt@kernel.org>
Cc:     linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org,
        linux-arm-msm@vger.kernel.org, devicetree@vger.kernel.org,
        Sibi Sankar <quic_sibis@quicinc.com>,
        Rajendra Nayak <quic_rjendra@quicinc.com>
References: <cover.1681799201.git.quic_schowdhu@quicinc.com>
 <142bfd034c12c245cda9f1dee20a05188b63494d.1681799201.git.quic_schowdhu@quicinc.com>
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From:   Bryan O'Donoghue <pure.logic@nexus-software.ie>
In-Reply-To: <142bfd034c12c245cda9f1dee20a05188b63494d.1681799201.git.quic_schowdhu@quicinc.com>
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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