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Subject[PATCH] thermal: create softlink by name for thermal_zone and cooling_device
From
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.

Signed-off-by: Wei Wang <wvw@google.com>
---
drivers/thermal/thermal_core.c | 23 +++++++++++++++++++++--
1 file changed, 21 insertions(+), 2 deletions(-)

diff --git a/drivers/thermal/thermal_core.c b/drivers/thermal/thermal_core.c
index d4481cc8958f..0ff8fb1d7b0a 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;

@@ -954,7 +957,7 @@ __thermal_cooling_device_register(struct device_node *np,
struct thermal_zone_device *pos = NULL;
int result;

- if (type && strlen(type) >= THERMAL_NAME_LENGTH)
+ if (!type || !type[0] || strlen(type) >= THERMAL_NAME_LENGTH)
return ERR_PTR(-EINVAL);

if (!ops || !ops->get_max_state || !ops->get_cur_state ||
@@ -989,9 +992,15 @@ __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 */
@@ -1157,6 +1166,8 @@ 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);

@@ -1340,6 +1351,12 @@ 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 */
@@ -1411,6 +1428,8 @@ 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);

--
2.23.0.700.g56cf767bdb-goog
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