Re: [PATCH v3 2/4] soc: qcom: Add SoC sleep stats driver

Bjorn Andersson
2020-03-07T06:42:37Z

On Thu 05 Mar 23:23 PST 2020, Maulik Shah wrote:

> From: Mahesh Sivasubramanian <msivasub@codeaurora.org>
>
> Let's add a driver to read the the stats from remote processor
> and export to debugfs.
>
> The driver creates "soc_sleep_stats" directory in debugfs and adds
> files for various low power mode available. Below is sample output
> with command
>

Given that this doesn't provide some generic stats for SoCs, how about
naming the whole thing qcom_sleep_stats instead?

> cat /sys/kernel/debug/soc_sleep_stats/ddr
> count = 0
> Last Entered At = 0
> Last Exited At = 0
> Accumulated Duration = 0
>
> Signed-off-by: Mahesh Sivasubramanian <msivasub@codeaurora.org>
> Signed-off-by: Lina Iyer <ilina@codeaurora.org>
> Signed-off-by: Maulik Shah <mkshah@codeaurora.org>
> ---

Please include a changelog here.

> drivers/soc/qcom/Kconfig | 9 ++
> drivers/soc/qcom/Makefile | 1 +
> drivers/soc/qcom/soc_sleep_stats.c | 248 +++++++++++++++++++++++++++++++++++++
> 3 files changed, 258 insertions(+)
> create mode 100644 drivers/soc/qcom/soc_sleep_stats.c
>
> diff --git a/drivers/soc/qcom/Kconfig b/drivers/soc/qcom/Kconfig
> index d0a73e7..08bc0df3 100644
> --- a/drivers/soc/qcom/Kconfig
> +++ b/drivers/soc/qcom/Kconfig
> @@ -185,6 +185,15 @@ config QCOM_SOCINFO
> Say yes here to support the Qualcomm socinfo driver, providing
> information about the SoC to user space.
>
> +config QCOM_SOC_SLEEP_STATS
> + tristate "Qualcomm Technologies, Inc. (QTI) SoC sleep stats driver"
> + depends on ARCH_QCOM && DEBUG_FS || COMPILE_TEST
> + help
> + Qualcomm Technologies, Inc. (QTI) SoC sleep stats driver to read
> + the shared memory exported by the remote processor related to
> + various SoC level low power modes statistics and export to debugfs
> + interface.
> +
> config QCOM_WCNSS_CTRL
> tristate "Qualcomm WCNSS control driver"
> depends on ARCH_QCOM || COMPILE_TEST
> diff --git a/drivers/soc/qcom/Makefile b/drivers/soc/qcom/Makefile
> index 9fb35c8..e6bd052 100644
> --- a/drivers/soc/qcom/Makefile
> +++ b/drivers/soc/qcom/Makefile
> @@ -20,6 +20,7 @@ obj-$(CONFIG_QCOM_SMEM_STATE) += smem_state.o
> obj-$(CONFIG_QCOM_SMP2P) += smp2p.o
> obj-$(CONFIG_QCOM_SMSM) += smsm.o
> obj-$(CONFIG_QCOM_SOCINFO) += socinfo.o
> +obj-$(CONFIG_QCOM_SOC_SLEEP_STATS) += soc_sleep_stats.o
> obj-$(CONFIG_QCOM_WCNSS_CTRL) += wcnss_ctrl.o
> obj-$(CONFIG_QCOM_APR) += apr.o
> obj-$(CONFIG_QCOM_LLCC) += llcc-qcom.o
> diff --git a/drivers/soc/qcom/soc_sleep_stats.c b/drivers/soc/qcom/soc_sleep_stats.c
> new file mode 100644
> index 00000000..79a14d2
> --- /dev/null
> +++ b/drivers/soc/qcom/soc_sleep_stats.c
> @@ -0,0 +1,248 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * Copyright (c) 2011-2020, The Linux Foundation. All rights reserved.
> + */
> +
> +#include <linux/debugfs.h>
> +#include <linux/device.h>
> +#include <linux/io.h>
> +#include <linux/module.h>
> +#include <linux/of.h>
> +#include <linux/platform_device.h>
> +#include <linux/seq_file.h>
> +
> +#include <linux/soc/qcom/smem.h>
> +#include <clocksource/arm_arch_timer.h>
> +
> +#define MODEM_ITEM_ID 605
> +#define ADSP_ITEM_ID 606
> +#define CDSP_ITEM_ID 607
> +#define SLPI_ITEM_ID 608
> +#define GPU_ITEM_ID 609
> +#define DISPLAY_ITEM_ID 610

I don't think these defines adds any value, just plug in the numbers in
the table directly.

> +
> +#define PID_APSS 0
> +#define PID_MODEM 1
> +#define PID_ADSP 2
> +#define PID_SLPI 3
> +#define PID_CDSP 5

Ditto.

> +
> +#define NAME_LENGTH 5

As I suggested below, this isn't 5 - it's sizeof(u32) + 1, and as such
it doesn't add value to carry it as a define that doesn't fit on the
same screen when reading the code below.

> +
> +#define STAT_TYPE_ADDR 0x0
> +#define COUNT_ADDR 0x4
> +#define LAST_ENTERED_AT_ADDR 0x8
> +#define LAST_EXITED_AT_ADDR 0x10
> +#define ACCUMULATED_ADDR 0x18
> +#define CLIENT_VOTES_ADDR 0x1c
> +
> +struct subsystem_data {
> + const char *name;
> + u32 item_id;

"smem_item"

> + u32 pid;
> +};
> +
> +static struct subsystem_data subsystems[] = {
> + { "modem", MODEM_ITEM_ID, PID_MODEM },
> + { "adsp", ADSP_ITEM_ID, PID_ADSP },
> + { "cdsp", CDSP_ITEM_ID, PID_CDSP },
> + { "slpi", SLPI_ITEM_ID, PID_SLPI },
> + { "gpu", GPU_ITEM_ID, PID_APSS },
> + { "display", DISPLAY_ITEM_ID, PID_APSS },
> +};
> +
> +struct stats_config {
> + unsigned int offset_addr;
> + unsigned int num_records;
> + bool appended_stats_avail;
> +};
> +
> +static const struct stats_config *config;

Add this to soc_sleep_stats_data and pass that as s->private instead of
just the reg, to avoid the global variable.

> +
> +struct soc_sleep_stats_data {
> + phys_addr_t stats_base;

This can be a local variable in soc_sleep_stats_probe()

> + resource_size_t stats_size;

Ditto.

> + void __iomem *reg;
> + struct dentry *root;
> +};
> +
> +struct entry {

Can you please give this struct a slightly less generic name?

> + u32 stat_type;
> + u32 count;
> + u64 last_entered_at;
> + u64 last_exited_at;
> + u64 accumulated;
> +};
> +
> +struct appended_entry {
> + u32 client_votes;
> + u32 reserved[3];
> +};
> +
> +static void print_sleep_stats(struct seq_file *s, struct entry *e)
> +{
> + seq_printf(s, "Count = %u\n", e->count);
> + seq_printf(s, "Last Entered At = %llu\n", e->last_entered_at);
> + seq_printf(s, "Last Exited At = %llu\n", e->last_exited_at);
> + seq_printf(s, "Accumulated Duration = %llu\n", e->accumulated);
> +}
> +
> +static int subsystem_sleep_stats_show(struct seq_file *s, void *d)
> +{
> + struct subsystem_data *subsystem = s->private;
> + struct entry *e;
> +
> + e = qcom_smem_get(subsystem->pid, subsystem->item_id, NULL);
> + if (IS_ERR(e))
> + return PTR_ERR(e);
> +
> + /*
> + * If a subsystem is in sleep when reading the sleep stats adjust
> + * the accumulated sleep duration to show actual sleep time.
> + */
> + if (e->last_entered_at > e->last_exited_at)
> + e->accumulated += (arch_timer_read_counter()
> + - e->last_entered_at);

How is this supposed to work? "e" is a pointer to the actual data in
smem, so every time "subsystem_sleep_stats" is shown we'll add the delta
since last_entered_at to a persistent variable?

Won't this make the "accumulated" value depend on the number of times
you have read the data?

I'm guessing that you're actually looking for:

accumulated + now() - last_entered_at

In which case, making a stack-local copy of the data in e and then doing
this addition should provide the result you're looking for.

> +
> + print_sleep_stats(s, e);
> +
> + return 0;
> +}
> +
> +static int soc_sleep_stats_show(struct seq_file *s, void *d)
> +{
> + void __iomem *reg = s->private;
> + struct entry e;
> +
> + e.count = readl_relaxed(reg + COUNT_ADDR);

No need to "_relax" these reads.

> + e.last_entered_at = readq_relaxed(reg + LAST_ENTERED_AT_ADDR);
> + e.last_exited_at = readq_relaxed(reg + LAST_EXITED_AT_ADDR);
> + e.accumulated = readq_relaxed(reg + ACCUMULATED_ADDR);
> +
> + print_sleep_stats(s, &e);
> +
> + if (config->appended_stats_avail) {
> + struct appended_entry ae;
> +
> + ae.client_votes = readl_relaxed(reg + CLIENT_VOTES_ADDR);
> + seq_printf(s, "Client_votes = %#x\n", ae.client_votes);
> + }
> +
> + return 0;
> +}
> +
> +DEFINE_SHOW_ATTRIBUTE(soc_sleep_stats);
> +DEFINE_SHOW_ATTRIBUTE(subsystem_sleep_stats);
> +
> +static void create_debugfs_entries(struct soc_sleep_stats_data *drv)
> +{
> + struct entry *e;
> + char stat_type[NAME_LENGTH] = {0};

NAME_LENGTH is sizeof(u32) + 1 and will never change, so I think the use
of a define only serves to obfuscate things.

> + u32 offset, type;
> + int i;
> +
> + drv->root = debugfs_create_dir("soc_sleep_stats", NULL);
> +
> + for (i = 0; i < config->num_records; i++) {
> + offset = STAT_TYPE_ADDR + (i * sizeof(struct entry));
> +
> + if (config->appended_stats_avail)
> + offset += i * sizeof(struct appended_entry);
> +
> + type = le32_to_cpu(readl_relaxed(drv->reg + offset));

readl_relaxed() is already CPU endian, so this isn't right.

And please drop the "_relaxed".

> + memcpy(stat_type, &type, sizeof(u32));
> + debugfs_create_file(stat_type, 0444, drv->root,
> + drv->reg + offset,
> + &soc_sleep_stats_fops);
> + }
> +
> + for (i = 0; i < ARRAY_SIZE(subsystems); i++) {
> + e = qcom_smem_get(subsystems[i].pid, subsystems[i].item_id,
> + NULL);

Feel free to ignore the 80-char "limit", and drop the empty line before
the check below.

> +
> + if (IS_ERR(e))
> + continue;
> +
> + debugfs_create_file(subsystems[i].name, 0444, drv->root,
> + &subsystems[i],
> + &subsystem_sleep_stats_fops);
> + }
> +}
> +
> +static int soc_sleep_stats_probe(struct platform_device *pdev)
> +{
> + struct soc_sleep_stats_data *drv;
> + struct resource *res;
> + void __iomem *offset_addr;
> +
> + drv = devm_kzalloc(&pdev->dev, sizeof(*drv), GFP_KERNEL);
> + if (!drv)
> + return -ENOMEM;
> +
> + config = device_get_match_data(&pdev->dev);
> + if (!config)
> + return -ENODEV;
> +
> + res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> + if (!res)
> + return PTR_ERR(res);
> +
> + offset_addr = devm_ioremap(&pdev->dev,
> + res->start + config->offset_addr,
> + sizeof(u32));

No need to devm this.

> + if (IS_ERR(offset_addr))
> + return PTR_ERR(offset_addr);
> +
> + drv->stats_base = res->start | readl_relaxed(offset_addr);
> + drv->stats_size = resource_size(res);

As stated above, these can be local variables...

> + devm_iounmap(&pdev->dev, offset_addr);
> +
> + drv->reg = devm_ioremap(&pdev->dev, drv->stats_base, drv->stats_size);
> + if (!drv->reg)
> + return -ENOMEM;
> +
> + create_debugfs_entries(drv);
> + platform_set_drvdata(pdev, drv);
> +
> + return 0;
> +}
> +
> +static int soc_sleep_stats_remove(struct platform_device *pdev)
> +{
> + struct soc_sleep_stats_data *drv = platform_get_drvdata(pdev);
> +
> + debugfs_remove_recursive(drv->root);
> +
> + return 0;
> +}
> +
> +static const struct stats_config rpm_data = {
> + .offset_addr = 0x14,
> + .num_records = 2,
> + .appended_stats_avail = true,
> +};
> +
> +static const struct stats_config rpmh_data = {
> + .offset_addr = 0x4,
> + .num_records = 3,
> + .appended_stats_avail = false,
> +};
> +
> +static const struct of_device_id soc_sleep_stats_table[] = {
> + { .compatible = "qcom,rpm-sleep-stats", .data = &rpm_data},
> + { .compatible = "qcom,rpmh-sleep-stats", .data = &rpmh_data},

Please add an extra space between data and '}' in these two.

Thanks,
Bjorn

> + { }
> +};
> +
> +static struct platform_driver soc_sleep_stats_driver = {
> + .probe = soc_sleep_stats_probe,
> + .remove = soc_sleep_stats_remove,
> + .driver = {
> + .name = "soc_sleep_stats",
> + .of_match_table = soc_sleep_stats_table,
> + },
> +};
> +module_platform_driver(soc_sleep_stats_driver);
> +
> +MODULE_DESCRIPTION("Qualcomm Technologies, Inc. (QTI) SoC Sleep Stats driver");
> +MODULE_LICENSE("GPL v2");
> --
> QUALCOMM INDIA, on behalf of Qualcomm Innovation Center, Inc. is a member
> of Code Aurora Forum, hosted by The Linux Foundation