Re: [PATCH v2] PM: runtime: Add support to disable wakeup sources

[Rafael J. Wysocki]

On Thu, Aug 25, 2022 at 7:35 PM Vimal Kumar <vimal.kumar32@xxxxxxxxx> wrote:
>
> User could find many wakeup sources available in the bsp, which
> they won't be using. Currently users can only get the status and
> list of enabled wakeup sources, but users can't disable it runtime.

What about using the wakeup attribute for devices in sysfs?  That
effectively disables/enables a wakeup source.

> It's very difficult to find the driver for each wakeup sources from
> where it's getting enabled and make the changes for disabling it.

Why do you need to enable/disable them individually, though?

> This will help users to disable any wakeup sources at runtime,
> avoiding any code change and re-compilation. A new class attribute
> "disable_ws" will be added in the wakeup calss. If user want to disable
> any wakeup sources, user need to find the wakeup dev node associated
> with the particular wakeup source and write the devnode name to the
> class attribute "disable_ws".
>
> Example:
> Need to disable the wakeup source '1c08000.qcom,pcie'. The dev node
> associated with this wakeup source is:
> cat /sys/class/wakeup3/name ==> "1c08000.qcom,pcie", then for disabling
> this wakeup source :
>         echo wakeup3 > /sys/class/wakeup/disable_ws

Wouldn't it be more straightforward to add a "disable" attribute for
wakeup sources?

> Co-developed-by: Mintu Patel <mintupatel89@xxxxxxxxx>
> Signed-off-by: Mintu Patel <mintupatel89@xxxxxxxxx>
> Co-developed-by: Vishal Badole <badolevishal1116@xxxxxxxxx>
> Signed-off-by: Vishal Badole <badolevishal1116@xxxxxxxxx>
> Signed-off-by: Vimal Kumar <vimal.kumar32@xxxxxxxxx>
> ---
>  Documentation/ABI/testing/sysfs-class-wakeup | 16 +++++
>  drivers/base/power/wakeup_stats.c            | 65 +++++++++++++++++++-
>  2 files changed, 80 insertions(+), 1 deletion(-)
>
> diff --git a/Documentation/ABI/testing/sysfs-class-wakeup b/Documentation/ABI/testing/sysfs-class-wakeup
> index 754aab8b6dcd..75b9a6fe737a 100644
> --- a/Documentation/ABI/testing/sysfs-class-wakeup
> +++ b/Documentation/ABI/testing/sysfs-class-wakeup
> @@ -74,3 +74,19 @@ Contact:     Tri Vo <trong@xxxxxxxxxxx>
>  Description:
>                 The file contains the total amount of time this wakeup source
>                 has been preventing autosleep, in milliseconds.
> +
> +What:          /sys/class/wakeup/disable_ws
> +Date:          Aug 2022
> +Contact:       Vimal Kumar <vimal.kumar@xxxxxxxxx>
> +Description:
> +               This file can be used to disable a wakeup source at runtime.
> +               If user want to disable any wakeup sources, user need to find
> +               the wakeup dev node associated with the particular wakeup source
> +               and write the devnode name to this file "disable_ws".
> +
> +               Example:
> +               If user Need to disable the wakeup source '1c08000.qcom,pcie', and
> +               the wakeup dev node associated with this wakeup source is:
> +                       cat /sys/class/wakeup3/name ==> "1c08000.qcom,pcie"
> +               Then for disabling this wakeup source :
> +                       echo wakeup3 > /sys/class/wakeup/disable_ws
> diff --git a/drivers/base/power/wakeup_stats.c b/drivers/base/power/wakeup_stats.c
> index 924fac493c4f..497402a28028 100644
> --- a/drivers/base/power/wakeup_stats.c
> +++ b/drivers/base/power/wakeup_stats.c
> @@ -15,6 +15,7 @@
>  #include <linux/kobject.h>
>  #include <linux/slab.h>
>  #include <linux/timekeeping.h>
> +#include <linux/uaccess.h>
>
>  #include "power.h"
>
> @@ -208,9 +209,71 @@ void wakeup_source_sysfs_remove(struct wakeup_source *ws)
>         device_unregister(ws->dev);
>  }
>
> +static ssize_t disable_ws_store(struct class *class,
> +                               struct class_attribute *attr,
> +                               const char *buf, size_t len)
> +{
> +       struct device           *dev;
> +       struct wakeup_source    *ws;
> +       char                    *ws_name;
> +       int                     status;
> +
> +       ws_name = kzalloc(len+1, GFP_KERNEL);
> +       if (!ws_name)
> +               return -ENOMEM;
> +
> +       if (sscanf(buf, "%s", ws_name) != 1)
> +               return -EFAULT;
> +
> +       dev = class_find_device_by_name(wakeup_class, ws_name);
> +       if (!dev) {
> +               pr_err("%s : wakeup device not found\n", __func__);
> +               return -EINVAL;
> +       }
> +
> +       ws = dev_get_drvdata(dev);
> +       if (ws->dev->parent != NULL) {
> +
> +               status = device_wakeup_disable(ws->dev->parent);
> +               if (status < 0) {
> +                       /* In case of virtual device, return code will be -EINVAL
> +                        * then unregister the wakeup source associated with it
> +                        */
> +                       wakeup_source_unregister(ws);
> +               }
> +       } else
> +               /* If the parent device is NULL, just unregister the wakeup source */
> +               wakeup_source_unregister(ws);
> +
> +       return len;
> +}
> +
> +static CLASS_ATTR_WO(disable_ws);
> +
> +static struct attribute *wakeup_class_attrs[] = {
> +       &class_attr_disable_ws.attr,
> +       NULL,
> +};
> +ATTRIBUTE_GROUPS(wakeup_class);
> +
>  static int __init wakeup_sources_sysfs_init(void)
>  {
> -       wakeup_class = class_create(THIS_MODULE, "wakeup");
> +       int status;
> +
> +       wakeup_class = kzalloc(sizeof(*wakeup_class), GFP_KERNEL);
> +       if (!wakeup_class)
> +               return -ENOMEM;
> +
> +       wakeup_class->name = "wakeup";
> +       wakeup_class->owner = THIS_MODULE;
> +       wakeup_class->class_groups = wakeup_class_groups;
> +
> +       status = class_register(wakeup_class);
> +
> +       if (status < 0) {
> +               pr_err("%s: class register failed %d\n", __func__, status);
> +               return status;
> +       }
>
>         return PTR_ERR_OR_ZERO(wakeup_class);
>  }
> --
> 2.25.1
>