thermal/drivers/devfreq_cooling: Use device name instead of auto-numbering

Currently the naming of a cooling device is just a cooling technique
followed by a number. When there are multiple cooling devices using
the same technique, it is impossible to clearly identify the related
device as this one is just a number.

For instance:

 thermal-devfreq-0
 thermal-devfreq-1
 etc ...

The 'thermal' prefix is redundant with the subsystem namespace. This
patch removes the 'thermal' prefix and changes the number by the device
name. So the naming above becomes:

 devfreq-5000000.gpu
 devfreq-1d84000.ufshc
 etc ...
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Reviewed-by: Lukasz Luba <lukasz.luba@arm.com>
Link: https://lore.kernel.org/r/20210314111333.16551-3-daniel.lezcano@linaro.org

drivers/thermal/devfreq_cooling.c

@@ -14,7 +14,6 @@
 #include <linux/devfreq_cooling.h>
 #include <linux/energy_model.h>
 #include <linux/export.h>
-#include <linux/idr.h>
 #include <linux/slab.h>
 #include <linux/pm_opp.h>
 #include <linux/pm_qos.h>
@@ -25,11 +24,8 @@
 #define HZ_PER_KHZ		1000
 #define SCALE_ERROR_MITIGATION	100
 
-static DEFINE_IDA(devfreq_ida);
-
 /**
  * struct devfreq_cooling_device - Devfreq cooling device
- * @id:		unique integer value corresponding to each
  *		devfreq_cooling_device registered.
  * @cdev:	Pointer to associated thermal cooling device.
  * @devfreq:	Pointer to associated devfreq device.
@@ -51,7 +47,6 @@ static DEFINE_IDA(devfreq_ida);
  * @em_pd:		Energy Model for the associated Devfreq device
  */
 struct devfreq_cooling_device {
-	int id;
 	struct thermal_cooling_device *cdev;
 	struct devfreq *devfreq;
 	unsigned long cooling_state;
@@ -363,7 +358,7 @@ of_devfreq_cooling_register_power(struct device_node *np, struct devfreq *df,
 	struct thermal_cooling_device *cdev;
 	struct device *dev = df->dev.parent;
 	struct devfreq_cooling_device *dfc;
-	char dev_name[THERMAL_NAME_LENGTH];
+	char *name;
 	int err, num_opps;
 
 	dfc = kzalloc(sizeof(*dfc), GFP_KERNEL);
@@ -407,30 +402,27 @@ of_devfreq_cooling_register_power(struct device_node *np, struct devfreq *df,
 	if (err < 0)
 		goto free_table;
 
-	err = ida_simple_get(&devfreq_ida, 0, 0, GFP_KERNEL);
-	if (err < 0)
+	cdev = ERR_PTR(-ENOMEM);
+	name = kasprintf(GFP_KERNEL, "devfreq-%s", dev_name(dev));
+	if (!name)
 		goto remove_qos_req;
 
-	dfc->id = err;
-
-	snprintf(dev_name, sizeof(dev_name), "thermal-devfreq-%d", dfc->id);
-
-	cdev = thermal_of_cooling_device_register(np, dev_name, dfc,
+	cdev = thermal_of_cooling_device_register(np, name, dfc,
 						  &devfreq_cooling_ops);
+	kfree(name);
+
 	if (IS_ERR(cdev)) {
 		err = PTR_ERR(cdev);
 		dev_err(dev,
 			"Failed to register devfreq cooling device (%d)\n",
 			err);
-		goto release_ida;
+		goto remove_qos_req;
 	}
 
 	dfc->cdev = cdev;
 
 	return cdev;
 
-release_ida:
-	ida_simple_remove(&devfreq_ida, dfc->id);
 remove_qos_req:
 	dev_pm_qos_remove_request(&dfc->req_max_freq);
 free_table:
@@ -527,7 +519,6 @@ void devfreq_cooling_unregister(struct thermal_cooling_device *cdev)
 	dev = dfc->devfreq->dev.parent;
 
 	thermal_cooling_device_unregister(dfc->cdev);
-	ida_simple_remove(&devfreq_ida, dfc->id);
 	dev_pm_qos_remove_request(&dfc->req_max_freq);
 
 	em_dev_unregister_perf_domain(dev);