Re: [PATCH v3 2/2] soc: qcom: Introduce RPM master stats driver

[Konrad Dybcio]

On 17.04.2023 10:20, Manivannan Sadhasivam wrote:
> On Mon, Apr 17, 2023 at 09:14:39AM +0200, Konrad Dybcio wrote:
>>
>>
>> On 16.04.2023 16:20, Manivannan Sadhasivam wrote:
>>> On Fri, Apr 14, 2023 at 01:37:18PM +0200, Konrad Dybcio wrote:
>>>> Introduce a driver to query and expose detailed, per-subsystem (as opposed
>>>> to the existing qcom_stats driver which exposes SoC-wide data) about low
>>>> power mode states of a given RPM master. That includes the APSS (ARM),
>>>> MPSS (modem) and other remote cores, depending on the platform
>>>> configuration.
>>>>
>>>> This is a vastly cleaned up and restructured version of a similar
>>>> driver found in msm-5.4.
>>>>
>>>> Signed-off-by: Konrad Dybcio <konrad.dybcio@xxxxxxxxxx>
>>>> ---
>>>>  drivers/soc/qcom/Kconfig            |  11 +++
>>>>  drivers/soc/qcom/Makefile           |   1 +
>>>>  drivers/soc/qcom/rpm_master_stats.c | 160 ++++++++++++++++++++++++++++++++++++
>>>>  3 files changed, 172 insertions(+)
>>>>
>>>> diff --git a/drivers/soc/qcom/Kconfig b/drivers/soc/qcom/Kconfig
>>>> index a491718f8064..e597799e8121 100644
>>>> --- a/drivers/soc/qcom/Kconfig
>>>> +++ b/drivers/soc/qcom/Kconfig
>>>> @@ -135,6 +135,17 @@ config QCOM_RMTFS_MEM
>>>>  
>>>>  	  Say y here if you intend to boot the modem remoteproc.
>>>>  
>>>> +config QCOM_RPM_MASTER_STATS
>>>> +	tristate "Qualcomm RPM Master stats"
>>>> +	depends on ARCH_QCOM || COMPILE_TEST
>>>> +	help
>>>> +	  The RPM Master sleep stats driver provides detailed per-subsystem
>>>> +	  sleep/wake data, read from the RPM message RAM. It can be used to
>>>> +	  assess whether all the low-power modes available are entered as
>>>> +	  expected or to check which part of the SoC prevents it from sleeping.
>>>> +
>>>> +	  Say y here if you intend to debug or monitor platform sleep.
>>>> +
>>>>  config QCOM_RPMH
>>>>  	tristate "Qualcomm RPM-Hardened (RPMH) Communication"
>>>>  	depends on ARCH_QCOM || COMPILE_TEST
>>>> diff --git a/drivers/soc/qcom/Makefile b/drivers/soc/qcom/Makefile
>>>> index 0f43a88b4894..7349371fdea1 100644
>>>> --- a/drivers/soc/qcom/Makefile
>>>> +++ b/drivers/soc/qcom/Makefile
>>>> @@ -14,6 +14,7 @@ obj-$(CONFIG_QCOM_QMI_HELPERS)	+= qmi_helpers.o
>>>>  qmi_helpers-y	+= qmi_encdec.o qmi_interface.o
>>>>  obj-$(CONFIG_QCOM_RAMP_CTRL)	+= ramp_controller.o
>>>>  obj-$(CONFIG_QCOM_RMTFS_MEM)	+= rmtfs_mem.o
>>>> +obj-$(CONFIG_QCOM_RPM_MASTER_STATS)	+= rpm_master_stats.o
>>>>  obj-$(CONFIG_QCOM_RPMH)		+= qcom_rpmh.o
>>>>  qcom_rpmh-y			+= rpmh-rsc.o
>>>>  qcom_rpmh-y			+= rpmh.o
>>>> diff --git a/drivers/soc/qcom/rpm_master_stats.c b/drivers/soc/qcom/rpm_master_stats.c
>>>> new file mode 100644
>>>> index 000000000000..73080c92bf89
>>>> --- /dev/null
>>>> +++ b/drivers/soc/qcom/rpm_master_stats.c
>>>> @@ -0,0 +1,160 @@
>>>> +// SPDX-License-Identifier: GPL-2.0-only
>>>> +/*
>>>> + * Copyright (c) 2012-2020, The Linux Foundation. All rights reserved.
>>>> + * Copyright (c) 2023, Linaro Limited
>>>> + *
>>>> + * This driver supports what is known as "Master Stats v2", which seems to be
>>>> + * the only version which has ever shipped, all the way from 2013 to 2023.
>>>
>>> It'd better to mention "Qualcomm downstream" in the somewhere above comment to
>>> make it clear for users.
>> Ack
>>
>>>
>>>> + */
>>>> +
>>>> +#include <linux/debugfs.h>
>>>> +#include <linux/io.h>
>>>> +#include <linux/module.h>
>>>> +#include <linux/of.h>
>>>> +#include <linux/of_address.h>
>>>> +#include <linux/platform_device.h>
>>>> +
>>>> +struct master_stats_data {
>>>> +	void __iomem *base;
>>>> +	const char *label;
>>>> +};
>>>> +
>>>> +struct rpm_master_stats {
>>>> +	uint32_t active_cores;
>>>> +	uint32_t num_shutdowns;
>>>> +	uint64_t shutdown_req;
>>>> +	uint64_t wakeup_idx;
>>>> +	uint64_t bringup_req;
>>>> +	uint64_t bringup_ack;
>>>> +	uint32_t wakeup_reason; /* 0 = "rude wakeup", 1 = scheduled wakeup */
>>>> +	uint32_t last_sleep_trans_dur;
>>>> +	uint32_t last_wake_trans_dur;
>>>> +
>>>> +	/* Per-subsystem (*not necessarily* SoC-wide) XO shutdown stats */
>>>> +	uint32_t xo_count;
>>>> +	uint64_t xo_last_enter;
>>>> +	uint64_t last_exit;
>>>> +	uint64_t xo_total_dur;
>>>
>>> Why can't you use u64, u32?
>> Brain derp!
>>
>>>
>>> Also, sort these members as below:
>>>
>>> u64
>>> u32
>> No, it's the way this data is structured in the
>> memory and we copy it as a whole.
>>
> 
> Ok, in that case you'd need __packed.
> 
>>>
>>>> +};
>>>> +
> 
> [...]
> 
>>>> +		/*
>>>> +		 * Generally it's not advised to fail on debugfs errors, but this
>>>> +		 * driver's only job is exposing data therein.
>>>> +		 */
>>>> +		dent = debugfs_create_file(d[i].label, 0444, root,
>>>> +					   &d[i], &master_stats_fops);
>>>> +		if (!dent) {
>>>
>>> Don't check for NULL, instead use IS_ERR() if you really care about error
>>> checking here.
>> "This function will return a pointer to a dentry if
>> it succeeds. This pointer must be passed to the
>> debugfs_remove function when the file is to be removed
>> (no automatic cleanup happens if your module is unloaded,
>> you are responsible here.) If an error occurs, NULL will
>> be returned."
> 
> This seems to be the old comment. Take a look at the updated one in mainline:
> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/fs/debugfs/inode.c#n468
> 
> Greg changed the semantics of the debugfs APIs a while back but the kernel doc
> was updated recently:
> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/fs/debugfs/inode.c?id=d3002468cb5d5da11e22145c9af32facd5c34352
Okay, ack to both. I'll fix all that and resend!

Konrad
> 
> - Mani
> 
>>
>>>
>>>> +			debugfs_remove_recursive(root);
>>>> +			return -EINVAL;
>>>> +		}
>>>> +	}
>>>> +
>>>> +	device_set_pm_not_required(dev);
>>>> +
>>>> +	return 0;
>>>> +}
>>>> +
>>>> +static void master_stats_remove(struct platform_device *pdev)
>>>> +{
>>>> +	struct dentry *root = platform_get_drvdata(pdev);
>>>> +
>>>> +	debugfs_remove_recursive(root);
>>>> +}
>>>> +
>>>> +static const struct of_device_id rpm_master_table[] = {
>>>> +	{ .compatible = "qcom,rpm-master-stats" },
>>>> +	{ },
>>>> +};
>>>> +
>>>> +static struct platform_driver master_stats_driver = {
>>>> +	.probe = master_stats_probe,
>>>> +	.remove_new = master_stats_remove,
>>>> +	.driver = {
>>>> +		.name = "rpm_master_stats",
>>>> +		.of_match_table = rpm_master_table,
>>>> +	},
>>>> +};
>>>> +module_platform_driver(master_stats_driver);
>>>> +
>>>> +MODULE_DESCRIPTION("RPM Master Statistics driver");
>>>
>>> Qualcomm RPM Master Statistics driver
>> Ack
>>
>> Konrad
>>>
>>> - Mani
>>>
>>>> +MODULE_LICENSE("GPL");
>>>>
>>>> -- 
>>>> 2.40.0
>>>>
>>>
>