[RFC,3/3] thermal/drivers/cpuidle_cooling: cpuidle cooling driver for non DT/ARM

diff --git a/drivers/thermal/Kconfig b/drivers/thermal/Kconfig
index 3d669a1774d3..3efe3df75337 100644
--- a/drivers/thermal/Kconfig
+++ b/drivers/thermal/Kconfig
@@ -193,6 +193,18 @@  config CPU_IDLE_THERMAL
 	  idle cycle.
 endif
 
+config CPU_IDLE_THERMAL_GENERIC
+	tristate "CPU idle cooling device"
+	depends on !CPU_THERMAL
+	select CPU_IDLE_THERMAL_CORE
+	help
+	  This implements the CPU cooling mechanism through
+	  idle injection. This will throttle the CPU by injecting
+	  idle cycle.
+
+	  This driver can also be built as a module. If so, the module will
+          be called cpuidle_cooling_generic.
+
 config DEVFREQ_THERMAL
 	bool "Generic device cooling support"
 	depends on PM_DEVFREQ
diff --git a/drivers/thermal/Makefile b/drivers/thermal/Makefile
index 769d025beb11..c6dce523ab2b 100644
--- a/drivers/thermal/Makefile
+++ b/drivers/thermal/Makefile
@@ -26,6 +26,8 @@  thermal_sys-$(CONFIG_CPU_FREQ_THERMAL)	+= cpufreq_cooling.o
 thermal_sys-$(CONFIG_CPU_IDLE_THERMAL_CORE)	+= cpuidle_cooling_core.o
 thermal_sys-$(CONFIG_CPU_IDLE_THERMAL)	+= cpuidle_cooling.o
 
+obj-$(CONFIG_CPU_IDLE_THERMAL_GENERIC) += cpuidle_cooling_generic.o
+
 # devfreq cooling
 thermal_sys-$(CONFIG_DEVFREQ_THERMAL) += devfreq_cooling.o
 
diff --git a/drivers/thermal/cpuidle_cooling_generic.c b/drivers/thermal/cpuidle_cooling_generic.c
new file mode 100644
index 000000000000..adb33dfba2e7
--- /dev/null
+++ b/drivers/thermal/cpuidle_cooling_generic.c
@@ -0,0 +1,155 @@ 
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Generic cpu idle cooling driver
+ * Copyright (c) 2021, Intel Corporation.
+ * All rights reserved.
+ *
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/cpufeature.h>
+#include <linux/cpuhotplug.h>
+#include <linux/idle_inject.h>
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/slab.h>
+#include <linux/thermal.h>
+#include <linux/topology.h>
+
+#include "cpuidle_cooling_core.h"
+
+#define IDLE_DURATION   10000
+#define IDLE_LATENCY    5000
+
+static int idle_duration_us = IDLE_DURATION;
+static int idle_latency_us = IDLE_LATENCY;
+
+module_param(idle_duration_us, int, 0644);
+MODULE_PARM_DESC(idle_duration_us,
+		 "Idle duration in us.");
+
+module_param(idle_latency_us, int, 0644);
+MODULE_PARM_DESC(idle_latency_us,
+		 "Idle latency in us.");
+
+struct cpuidle_cooling {
+	struct thermal_cooling_device *cdev;
+	struct idle_inject_device *ii_dev;
+	struct cpuidle_cooling_device *idle_cdev;
+};
+static DEFINE_PER_CPU(struct cpuidle_cooling, cooling_devs);
+static cpumask_t cpuidle_cpu_mask;
+
+static int cpuidle_cooling_register(int cpu)
+{
+	struct cpuidle_cooling *cooling_dev = &per_cpu(cooling_devs, cpu);
+	struct cpuidle_cooling_device *idle_cdev;
+	struct thermal_cooling_device *cdev;
+	struct idle_inject_device *ii_dev;
+	char *name;
+	int ret;
+
+	if (cpumask_test_cpu(cpu, &cpuidle_cpu_mask))
+		return 0;
+
+	idle_cdev = kzalloc(sizeof(*idle_cdev), GFP_KERNEL);
+	if (!idle_cdev) {
+		ret = -ENOMEM;
+		goto out;
+	}
+
+	ii_dev = idle_inject_register((struct cpumask *)cpumask_of(cpu));
+	if (!ii_dev) {
+		pr_err("idle_inject_register failed for cpu:%d\n", cpu);
+		ret = -EINVAL;
+		goto out_kfree;
+	}
+
+	idle_inject_set_duration(ii_dev, TICK_USEC, idle_duration_us);
+	idle_inject_set_latency(ii_dev, idle_latency_us);
+
+	idle_cdev->ii_dev = ii_dev;
+
+	name = kasprintf(GFP_KERNEL, "idle-%d", cpu);
+	if (!name) {
+		ret = -ENOMEM;
+		goto out_unregister;
+	}
+
+	cdev = thermal_cooling_device_register(name, idle_cdev,
+					       cpuidle_cooling_get_ops());
+	if (IS_ERR(cdev)) {
+		ret = PTR_ERR(cdev);
+		goto out_kfree_name;
+	}
+
+	pr_debug("%s: Idle injection set with idle duration=%u, latency=%u\n",
+		 name, idle_duration_us, idle_latency_us);
+
+	kfree(name);
+
+	cooling_dev->cdev = cdev;
+	cooling_dev->ii_dev = ii_dev;
+	cooling_dev->idle_cdev = idle_cdev;
+	cpumask_set_cpu(cpu, &cpuidle_cpu_mask);
+
+	return 0;
+
+out_kfree_name:
+	kfree(name);
+out_unregister:
+	idle_inject_unregister(ii_dev);
+out_kfree:
+	kfree(idle_cdev);
+out:
+	return ret;
+}
+
+static void cpuidle_cooling_unregister(int cpu)
+{
+	struct cpuidle_cooling *cooling_dev = &per_cpu(cooling_devs, cpu);
+
+	thermal_cooling_device_unregister(cooling_dev->cdev);
+	idle_inject_unregister(cooling_dev->ii_dev);
+	kfree(cooling_dev->idle_cdev);
+}
+
+static int cpuidle_cooling_cpu_online(unsigned int cpu)
+{
+	cpuidle_cooling_register(cpu);
+
+	return 0;
+}
+
+static enum cpuhp_state cpuidle_cooling_hp_state __read_mostly;
+
+static int __init cpuidle_cooling_init(void)
+{
+	int ret;
+
+	ret = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN,
+				"thermal/cpuidle_cooling:online",
+				cpuidle_cooling_cpu_online, NULL);
+	if (ret < 0)
+		return ret;
+
+	cpuidle_cooling_hp_state = ret;
+
+	return 0;
+}
+module_init(cpuidle_cooling_init)
+
+static void __exit cpuidle_cooling_exit(void)
+{
+	int i;
+
+	cpuhp_remove_state(cpuidle_cooling_hp_state);
+
+	for_each_cpu(i,	&cpuidle_cpu_mask) {
+		cpuidle_cooling_unregister(i);
+	}
+}
+module_exit(cpuidle_cooling_exit)
+
+MODULE_LICENSE("GPL v2");