thermal/drivers/cpuidle_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-idle-0
 thermal-idle-1
 thermal-idle-2
 thermal-idle-3
 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:

 idle-cpu0
 idle-cpu1
 idle-cpu2
 idle-cpu3
 etc ...
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Reviewed-by: Lukasz Luba <lukasz.luba@arm.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Link: https://lore.kernel.org/r/20210314111333.16551-4-daniel.lezcano@linaro.org

drivers/thermal/cpuidle_cooling.c

@@ -9,9 +9,9 @@
 
 #include <linux/cpu_cooling.h>
 #include <linux/cpuidle.h>
+#include <linux/device.h>
 #include <linux/err.h>
 #include <linux/idle_inject.h>
-#include <linux/idr.h>
 #include <linux/of_device.h>
 #include <linux/slab.h>
 #include <linux/thermal.h>
@@ -26,8 +26,6 @@ struct cpuidle_cooling_device {
 	unsigned long state;
 };
 
-static DEFINE_IDA(cpuidle_ida);
-
 /**
  * cpuidle_cooling_runtime - Running time computation
  * @idle_duration_us: CPU idle time to inject in microseconds
@@ -174,10 +172,11 @@ static int __cpuidle_cooling_register(struct device_node *np,
 	struct idle_inject_device *ii_dev;
 	struct cpuidle_cooling_device *idle_cdev;
 	struct thermal_cooling_device *cdev;
+	struct device *dev;
 	unsigned int idle_duration_us = TICK_USEC;
 	unsigned int latency_us = UINT_MAX;
-	char dev_name[THERMAL_NAME_LENGTH];
-	int id, ret;
+	char *name;
+	int ret;
 
 	idle_cdev = kzalloc(sizeof(*idle_cdev), GFP_KERNEL);
 	if (!idle_cdev) {
@@ -185,16 +184,10 @@ static int __cpuidle_cooling_register(struct device_node *np,
 		goto out;
 	}
 
-	id = ida_simple_get(&cpuidle_ida, 0, 0, GFP_KERNEL);
-	if (id < 0) {
-		ret = id;
-		goto out_kfree;
-	}
-
 	ii_dev = idle_inject_register(drv->cpumask);
 	if (!ii_dev) {
 		ret = -EINVAL;
-		goto out_id;
+		goto out_kfree;
 	}
 
 	of_property_read_u32(np, "duration-us", &idle_duration_us);
@@ -205,24 +198,30 @@ static int __cpuidle_cooling_register(struct device_node *np,
 
 	idle_cdev->ii_dev = ii_dev;
 
-	snprintf(dev_name, sizeof(dev_name), "thermal-idle-%d", id);
+	dev = get_cpu_device(cpumask_first(drv->cpumask));
 
-	cdev = thermal_of_cooling_device_register(np, dev_name, idle_cdev,
+	name = kasprintf(GFP_KERNEL, "idle-%s", dev_name(dev));
+	if (!name) {
+		ret = -ENOMEM;
+		goto out_unregister;
+	}
+
+	cdev = thermal_of_cooling_device_register(np, name, idle_cdev,
 						  &cpuidle_cooling_ops);
+	kfree(name);
+
 	if (IS_ERR(cdev)) {
 		ret = PTR_ERR(cdev);
 		goto out_unregister;
 	}
 
 	pr_debug("%s: Idle injection set with idle duration=%u, latency=%u\n",
-		 dev_name, idle_duration_us, latency_us);
+		 name, idle_duration_us, latency_us);
 
 	return 0;
 
 out_unregister:
 	idle_inject_unregister(ii_dev);
-out_id:
-	ida_simple_remove(&cpuidle_ida, id);
 out_kfree:
 	kfree(idle_cdev);
 out: