Re: [PATCH V6 2/3] soc: qcom: boot_stat: Add Driver Support for Boot Stats
From: Souradeep Chowdhury
Date: Fri May 12 2023 - 07:47:19 EST
On 5/11/2023 10:37 PM, Bjorn Andersson wrote:
On Tue, May 09, 2023 at 03:52:22AM -0700, 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
I would have preferred some way to implement this without spending
countless kB of RAM to occasionally read out two u32 values...
But pulling them out of /dev/mem is the only suggestion that comes to
mind... Perhaps dropping the MODULE_DEVICE_TABLE() to rely on an
explicit modprobe/insmod in the few cases where it's needed?
@Arnd, do you have any suggestion about how to handle this kind of debug
drivers?
Signed-off-by: Souradeep Chowdhury <quic_schowdhu@xxxxxxxxxxx>
---
.../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@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/qcom_boot_stats/abl_time
+Date: May 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 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);
You don't use this region past probe, so no need to keep it mapped, or
hang onto the pointer.
This means that you don't need struct bs_data, you can just stuff the
dentry pointer directly in the drvdata.
Ack
+ 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))
Please omit error handling in the debugfs api.
Ack
+ 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);
abl lives on the stack, pre_abl is a pointer to the stack, &pre_abl is a
pointer to this pointer and if I read the code correctly, in
__debugfs_create_file this value is stored in inode->i_private.
So I think this will only work if your stack isn't resused...
Ack
Regards,
Bjorn
+ debugfs_create_str("abl_time", 0400, drvdata->dbg_dir, (char **)&abl);
+
+ 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");
--
2.17.1