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SubjectRe: [PATCH v3 3/3] thermal: create softlink by name for thermal_zone and cooling_device
On Wed, Dec 04, 2019 at 11:19:53PM -0800, Wei Wang wrote:
> The paths thermal_zone%d and cooling_device%d are not intuitive and the
> numbers are subject to change due to device tree change. This usually
> leads to tree traversal in userspace code.
> The patch creates `tz-by-name' and `cdev-by-name' for thermal zone and
> cooling_device respectively.

This is useful, especially for systems with plenty of thermal zones :)

> Signed-off-by: Wei Wang <wvw@google.com>
> Reviewed-by: Amit Kucheria <amit.kucheria@linaro.org>
> ---
> drivers/thermal/thermal_core.c | 21 ++++++++++++++++++++-
> 1 file changed, 20 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/thermal/thermal_core.c b/drivers/thermal/thermal_core.c
> index 9db7f72e70f8..7872bd527f3f 100644
> --- a/drivers/thermal/thermal_core.c
> +++ b/drivers/thermal/thermal_core.c
> @@ -22,6 +22,7 @@
> #include <net/netlink.h>
> #include <net/genetlink.h>
> #include <linux/suspend.h>
> +#include <linux/kobject.h>
>
> #define CREATE_TRACE_POINTS
> #include <trace/events/thermal.h>
> @@ -46,6 +47,8 @@ static DEFINE_MUTEX(poweroff_lock);
>
> static atomic_t in_suspend;
> static bool power_off_triggered;
> +static struct kobject *cdev_link_kobj;
> +static struct kobject *tz_link_kobj;
>
> static struct thermal_governor *def_governor;
>
> @@ -999,9 +1002,15 @@ __thermal_cooling_device_register(struct device_node *np,
> return ERR_PTR(result);
> }
>
> - /* Add 'this' new cdev to the global cdev list */
> + /* Add 'this' new cdev to the global cdev list and create link*/
> mutex_lock(&thermal_list_lock);
> list_add(&cdev->node, &thermal_cdev_list);
> + if (!cdev_link_kobj)
> + cdev_link_kobj = kobject_create_and_add("cdev-by-name",
> + cdev->device.kobj.parent);
> + if (!cdev_link_kobj || sysfs_create_link(cdev_link_kobj,
> + &cdev->device.kobj, cdev->type))
> + dev_err(&cdev->device, "Failed to create cdev-by-name link\n");
> mutex_unlock(&thermal_list_lock);
>
> /* Update binding information for 'this' new cdev */
> @@ -1167,6 +1176,8 @@ void thermal_cooling_device_unregister(struct thermal_cooling_device *cdev)
> }
> }
> }
> + if (cdev_link_kobj)
> + sysfs_remove_link(cdev_link_kobj, cdev->type);
>
> mutex_unlock(&thermal_list_lock);
>
> @@ -1354,6 +1365,12 @@ thermal_zone_device_register(const char *type, int trips, int mask,
>
> mutex_lock(&thermal_list_lock);
> list_add_tail(&tz->node, &thermal_tz_list);
> + if (!tz_link_kobj)
> + tz_link_kobj = kobject_create_and_add("tz-by-name",
> + tz->device.kobj.parent);
> + if (!tz_link_kobj || sysfs_create_link(tz_link_kobj,
> + &tz->device.kobj, tz->type))
> + dev_err(&tz->device, "Failed to create tz-by-name link\n");
> mutex_unlock(&thermal_list_lock);
>
> /* Bind cooling devices for this zone */
> @@ -1425,6 +1442,8 @@ void thermal_zone_device_unregister(struct thermal_zone_device *tz)
> }
> }
> }
> + if (tz_link_kobj)
> + sysfs_remove_link(tz_link_kobj, tz->type);
>
> mutex_unlock(&thermal_list_lock);
>

Reviewed-by: Matthias Kaehlcke <mka@chromium.org>
Tested-by: Matthias Kaehlcke <mka@chromium.org>

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