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Message-ID: <155e7420-a231-cc5a-4626-e484c3595e18@linaro.org>
Date:   Fri, 14 Apr 2023 12:34:09 +0100
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Subject: Re: [PATCH V3 2/3] soc: qcom: boot_stat: Add Driver Support for Boot
 Stats
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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.1681375949.git.quic_schowdhu@quicinc.com>
 <65b1db8d7d95bf09f8314ed3bfd9d007d1edbf3b.1681375949.git.quic_schowdhu@quicinc.com>
From:   Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
In-Reply-To: <65b1db8d7d95bf09f8314ed3bfd9d007d1edbf3b.1681375949.git.quic_schowdhu@quicinc.com>
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On 13/04/2023 10:28, 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                     | 109 ++++++++++++++++++++++
>   4 files changed, 136 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..37d8e32
> --- /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 is 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..9b65aa1
> --- /dev/null
> +++ b/drivers/soc/qcom/boot_stats.c
> @@ -0,0 +1,109 @@
> +// 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;
> +
> +static struct boot_stats __iomem *boot_stats;
> +static struct dentry *dbg_dir;
> +
I would avoid global variables where possible, and allocate them 
dynamically.

In this case you could do that in probe and pass it(boot_stats) as 
argument to debugfs_create_file() and also set dbg_dir as 
dev_set_drvdata to be able to use it in remove.


----------------->cut<--------------
> +static ssize_t abl_read(struct file *filp, char __user *userbuf,
> +			size_t count, loff_t *ppos)
> +{
> +	char buf[20];
> +
> +	u32 abl_time = TO_MS(boot_stats->abl_end) - TO_MS(boot_stats->abl_start);
> +
> +	sprintf(buf, "%u ms\n", abl_time);
> +	return simple_read_from_buffer(userbuf, count, ppos, buf, strlen(buf));
> +}
> +
> +static const struct file_operations abl_fops = {
> +	.read = abl_read,
> +	.open = simple_open,
> +	.llseek = generic_file_llseek,
> +};
> +
--------------->cut<----------------
can be replaced with.

static int abl_show(struct seq_file *s_file, void *data)
{
         struct boot_stats *boot_stats = s_file->private;
	...
}

DEFINE_SHOW_ATTRIBUTE(abl);

> +static ssize_t pre_abl_read(struct file *filp, char __user *userbuf,
> +			    size_t count, loff_t *ppos)
> +{
> +	char buf[20];
> +
> +	sprintf(buf, "%u ms\n", TO_MS(boot_stats->abl_start));
> +	return simple_read_from_buffer(userbuf, count, ppos, buf, strlen(buf));
> +}
> +
> +static const struct file_operations pre_abl_fops = {
> +	.read = pre_abl_read,
> +	.open = simple_open,
> +	.llseek = generic_file_llseek,
> +};
> +
same here.

> +static int boot_stats_probe(struct platform_device *pdev)
> +{
> +	struct device *boot_stat = &pdev->dev;
> +
> +	dbg_dir = debugfs_create_dir(dev_name(&pdev->dev), NULL);
> +	if (IS_ERR(dbg_dir))
> +		return dev_err_probe(&pdev->dev, -ENOENT,
> +				     "failed to create debugfs directory");
> +
> +	boot_stats = of_iomap(boot_stat->of_node, 0);

may be devm_of_iomap?

> +	if (!boot_stats)
> +		return dev_err_probe(&pdev->dev, -ENOMEM,
> +				"failed to map imem region\n");
> +
> +	debugfs_create_file("pre_abl_time", 0200, dbg_dir, NULL, &pre_abl_fops);
> +	debugfs_create_file("abl_time", 0200, dbg_dir, NULL, &abl_fops);
> +
> +	return 0;
> +}
> +
> +static int boot_stats_remove(struct platform_device *pdev)
> +{
> +	debugfs_remove_recursive(dbg_dir);
> +	iounmap(boot_stats);
> +
> +	return 0;
> +}
> +
> +static const struct of_device_id boot_stats_dt_match[] = {
> +	{ .compatible = "qcom,sm8450-bootstats" },
> +	{ }
> +};
> +MODULE_DEVICE_TABLE(of, boot_stats_dt_match);
> +
> +static struct platform_driver boot_stat_driver = {
> +	.probe  = boot_stats_probe,
> +	.remove = boot_stats_remove,

consider using remove_new as its suggested that new drivers implement 
.remove_new as it returns void.
more details in  include/linux/platform_device.h


-srini

> +	.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");
> --
> 2.7.4
>