Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
Message-ID: <15feb92b-7a2a-4109-33df-68e030c33066@quicinc.com>
Date:   Sun, 14 May 2023 21:31:14 -0700
MIME-Version: 1.0
User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:102.0) Gecko/20100101
 Thunderbird/102.9.1
Subject: Re: [PATCH V6 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.1683628357.git.quic_schowdhu@quicinc.com>
 <35863b47c04c2edd7ae49c57d23682aba6111d4f.1683628357.git.quic_schowdhu@quicinc.com>
Content-Language: en-US
From:   Satya Durga Srinivasu Prabhala <quic_satyap@quicinc.com>
In-Reply-To: <35863b47c04c2edd7ae49c57d23682aba6111d4f.1683628357.git.quic_schowdhu@quicinc.com>
Content-Type: text/plain; charset="UTF-8"; format=flowed
Content-Transfer-Encoding: 7bit
Precedence: bulk


On 5/9/2023 3:52 AM, 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/qcom_boot_stats # cat abl_time
> 17898 ms
> /sys/kernel/debug/qcom_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>
> ---
>   .../ABI/testing/debugfs-driver-bootstat       |  17 +++
>   drivers/soc/qcom/Kconfig                      |  10 ++
>   drivers/soc/qcom/Makefile                     |   1 +
>   drivers/soc/qcom/boot_stats.c                 | 100 ++++++++++++++++++
>   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 000000000000..7127d15d9f15
> --- /dev/null
> +++ b/Documentation/ABI/testing/debugfs-driver-bootstat
> @@ -0,0 +1,17 @@
> +What:		/sys/kernel/debug/qcom_boot_stats/pre_abl_time
> +Date:           May 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/qcom_boot_stats/abl_time
> +Date:           May 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 a491718f8064..04141236dcdd 100644
> --- a/drivers/soc/qcom/Kconfig
> +++ b/drivers/soc/qcom/Kconfig
> @@ -16,6 +16,16 @@ 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
> +	depends on DEBUG_FS
> +	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 0f43a88b4894..ae7bda96a539 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 000000000000..ca67b6b5d8eb
> --- /dev/null
> +++ b/drivers/soc/qcom/boot_stats.c
> @@ -0,0 +1,100 @@
> +// 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)
> +
> +/**
> + *  struct boot_stats - timestamp information related to boot stats
> + *  @abl_start: Time for the starting point of the abl
> + *  @abl_end: Time when the kernel starts loading from abl
> + */
> +struct boot_stats {
> +	u32 abl_start;
> +	u32 abl_end;
> +} __packed;
> +
> +struct bs_data {
> +	struct boot_stats __iomem *b_stats;
> +	struct dentry *dbg_dir;
> +};
> +
> +static void populate_boot_stats(char *abl_str, char *pre_abl_str, struct
> bs_data *drvdata)
> +{
> +	 u32 abl_time, pre_abl_time;
> +
> +	 abl_time = TO_MS(drvdata->b_stats->abl_end) -
> TO_MS(drvdata->b_stats->abl_start);
> +	 sprintf(abl_str, "%u ms", abl_time);
> +
> +	 pre_abl_time =  TO_MS(drvdata->b_stats->abl_start);
> +	 sprintf(pre_abl_str, "%u ms", pre_abl_time);
> +}
> +
> +static int boot_stats_probe(struct platform_device *pdev)
> +{
> +	char abl_str[20], pre_abl_str[20], *abl, *pre_abl;
> +	struct device *bootstat_dev = &pdev->dev;
> +	struct bs_data *drvdata;
> +
> +	drvdata = devm_kzalloc(bootstat_dev, sizeof(*drvdata),
> GFP_KERNEL);
> +	if (!drvdata)
> +		return dev_err_probe(bootstat_dev, -ENOMEM, "failed to
> allocate memory");
> +	platform_set_drvdata(pdev, drvdata);
> +
> +	drvdata->b_stats = devm_of_iomap(bootstat_dev,
> bootstat_dev->of_node, 0, NULL);
> +	if (IS_ERR(drvdata->b_stats))
> +		return dev_err_probe(bootstat_dev,
> PTR_ERR(drvdata->b_stats),
> +				     "failed to map imem region");
> +
> +	drvdata->dbg_dir = debugfs_create_dir("qcom_boot_stats", NULL);
> +	if (IS_ERR(drvdata->dbg_dir))
> +		return dev_err_probe(bootstat_dev,
> PTR_ERR(drvdata->dbg_dir),
> +				     "failed to create debugfs
> directory");
> +
> +	populate_boot_stats(abl_str, pre_abl_str, drvdata);
> +	abl = abl_str;
> +	pre_abl = pre_abl_str;
> +
> +	debugfs_create_str("pre_abl_time", 0400, drvdata->dbg_dir, (char
> **)&pre_abl);
> +	debugfs_create_str("abl_time", 0400, drvdata->dbg_dir, (char
> **)&abl);

We would need these stats in Android "user" builds as well and debugfs 
won't be available in Android "user" builds. Please see below article. 
Can we move to sysfs instead of debugfs?

https://source.android.com/docs/core/architecture/kernel/using-debugfs-12

> +
> +	return 0;
> +}
> +
> +void boot_stats_remove(struct platform_device *pdev)
> +{
> +	struct bs_data *drvdata = platform_get_drvdata(pdev);
> +
> +	debugfs_remove_recursive(drvdata->dbg_dir);
> +}
> +
> +static const struct of_device_id boot_stats_dt_match[] = {
> +	{ .compatible = "qcom,imem-bootstats" },
> +	{ }
> +};
> +MODULE_DEVICE_TABLE(of, boot_stats_dt_match);
> +
> +static struct platform_driver boot_stat_driver = {
> +	.probe  = boot_stats_probe,
> +	.remove_new = boot_stats_remove,
> +	.driver = {
> +		.name = "qcom-boot-stats",
> +		.of_match_table = boot_stats_dt_match,
> +	},
> +};
> +module_platform_driver(boot_stat_driver);
> +
> +MODULE_DESCRIPTION("Qualcomm Technologies Inc. Boot Stat driver");
> +MODULE_LICENSE("GPL");