1 files changed, 271 insertions, 0 deletions
diff --git a/drivers/thermal/cpuidle_cooling.c b/drivers/thermal/cpuidle_cooling.c
new file mode 100644
index 000000000..7ecab4b16
--- /dev/null
+++ b/drivers/thermal/cpuidle_cooling.c
@@ -0,0 +1,271 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ *  Copyright (C) 2019 Linaro Limited.
+ *
+ *  Author: Daniel Lezcano <daniel.lezcano@linaro.org>
+ *
+ */
+#define pr_fmt(fmt) "cpuidle cooling: " fmt
+
+#include <linux/cpu_cooling.h>
+#include <linux/cpuidle.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>
+
+/**
+ * struct cpuidle_cooling_device - data for the idle cooling device
+ * @ii_dev: an atomic to keep track of the last task exiting the idle cycle
+ * @state: a normalized integer giving the state of the cooling device
+ */
+struct cpuidle_cooling_device {
+	struct idle_inject_device *ii_dev;
+	unsigned long state;
+};
+
+static DEFINE_IDA(cpuidle_ida);
+
+/**
+ * cpuidle_cooling_runtime - Running time computation
+ * @idle_duration_us: CPU idle time to inject in microseconds
+ * @state: a percentile based number
+ *
+ * The running duration is computed from the idle injection duration
+ * which is fixed. If we reach 100% of idle injection ratio, that
+ * means the running duration is zero. If we have a 50% ratio
+ * injection, that means we have equal duration for idle and for
+ * running duration.
+ *
+ * The formula is deduced as follows:
+ *
+ *  running = idle x ((100 / ratio) - 1)
+ *
+ * For precision purpose for integer math, we use the following:
+ *
+ *  running = (idle x 100) / ratio - idle
+ *
+ * For example, if we have an injected duration of 50%, then we end up
+ * with 10ms of idle injection and 10ms of running duration.
+ *
+ * Return: An unsigned int for a usec based runtime duration.
+ */
+static unsigned int cpuidle_cooling_runtime(unsigned int idle_duration_us,
+					    unsigned long state)
+{
+	if (!state)
+		return 0;
+
+	return ((idle_duration_us * 100) / state) - idle_duration_us;
+}
+
+/**
+ * cpuidle_cooling_get_max_state - Get the maximum state
+ * @cdev  : the thermal cooling device
+ * @state : a pointer to the state variable to be filled
+ *
+ * The function always returns 100 as the injection ratio. It is
+ * percentile based for consistency accross different platforms.
+ *
+ * Return: The function can not fail, it is always zero
+ */
+static int cpuidle_cooling_get_max_state(struct thermal_cooling_device *cdev,
+					 unsigned long *state)
+{
+	/*
+	 * Depending on the configuration or the hardware, the running
+	 * cycle and the idle cycle could be different. We want to
+	 * unify that to an 0..100 interval, so the set state
+	 * interface will be the same whatever the platform is.
+	 *
+	 * The state 100% will make the cluster 100% ... idle. A 0%
+	 * injection ratio means no idle injection at all and 50%
+	 * means for 10ms of idle injection, we have 10ms of running
+	 * time.
+	 */
+	*state = 100;
+
+	return 0;
+}
+
+/**
+ * cpuidle_cooling_get_cur_state - Get the current cooling state
+ * @cdev: the thermal cooling device
+ * @state: a pointer to the state
+ *
+ * The function just copies  the state value from the private thermal
+ * cooling device structure, the mapping is 1 <-> 1.
+ *
+ * Return: The function can not fail, it is always zero
+ */
+static int cpuidle_cooling_get_cur_state(struct thermal_cooling_device *cdev,
+					 unsigned long *state)
+{
+	struct cpuidle_cooling_device *idle_cdev = cdev->devdata;
+
+	*state = idle_cdev->state;
+
+	return 0;
+}
+
+/**
+ * cpuidle_cooling_set_cur_state - Set the current cooling state
+ * @cdev: the thermal cooling device
+ * @state: the target state
+ *
+ * The function checks first if we are initiating the mitigation which
+ * in turn wakes up all the idle injection tasks belonging to the idle
+ * cooling device. In any case, it updates the internal state for the
+ * cooling device.
+ *
+ * Return: The function can not fail, it is always zero
+ */
+static int cpuidle_cooling_set_cur_state(struct thermal_cooling_device *cdev,
+					 unsigned long state)
+{
+	struct cpuidle_cooling_device *idle_cdev = cdev->devdata;
+	struct idle_inject_device *ii_dev = idle_cdev->ii_dev;
+	unsigned long current_state = idle_cdev->state;
+	unsigned int runtime_us, idle_duration_us;
+
+	idle_cdev->state = state;
+
+	idle_inject_get_duration(ii_dev, &runtime_us, &idle_duration_us);
+
+	runtime_us = cpuidle_cooling_runtime(idle_duration_us, state);
+
+	idle_inject_set_duration(ii_dev, runtime_us, idle_duration_us);
+
+	if (current_state == 0 && state > 0) {
+		idle_inject_start(ii_dev);
+	} else if (current_state > 0 && !state)  {
+		idle_inject_stop(ii_dev);
+	}
+
+	return 0;
+}
+
+/**
+ * cpuidle_cooling_ops - thermal cooling device ops
+ */
+static struct thermal_cooling_device_ops cpuidle_cooling_ops = {
+	.get_max_state = cpuidle_cooling_get_max_state,
+	.get_cur_state = cpuidle_cooling_get_cur_state,
+	.set_cur_state = cpuidle_cooling_set_cur_state,
+};
+
+/**
+ * __cpuidle_cooling_register: register the cooling device
+ * @drv: a cpuidle driver structure pointer
+ * @np: a device node structure pointer used for the thermal binding
+ *
+ * This function is in charge of allocating the cpuidle cooling device
+ * structure, the idle injection, initialize them and register the
+ * cooling device to the thermal framework.
+ *
+ * Return: zero on success, a negative value returned by one of the
+ * underlying subsystem in case of error
+ */
+static int __cpuidle_cooling_register(struct device_node *np,
+				      struct cpuidle_driver *drv)
+{
+	struct idle_inject_device *ii_dev;
+	struct cpuidle_cooling_device *idle_cdev;
+	struct thermal_cooling_device *cdev;
+	unsigned int idle_duration_us = TICK_USEC;
+	unsigned int latency_us = UINT_MAX;
+	char dev_name[THERMAL_NAME_LENGTH];
+	int id, ret;
+
+	idle_cdev = kzalloc(sizeof(*idle_cdev), GFP_KERNEL);
+	if (!idle_cdev) {
+		ret = -ENOMEM;
+		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;
+	}
+
+	of_property_read_u32(np, "duration-us", &idle_duration_us);
+	of_property_read_u32(np, "exit-latency-us", &latency_us);
+
+	idle_inject_set_duration(ii_dev, TICK_USEC, idle_duration_us);
+	idle_inject_set_latency(ii_dev, latency_us);
+
+	idle_cdev->ii_dev = ii_dev;
+
+	snprintf(dev_name, sizeof(dev_name), "thermal-idle-%d", id);
+
+	cdev = thermal_of_cooling_device_register(np, dev_name, idle_cdev,
+						  &cpuidle_cooling_ops);
+	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);
+
+	return 0;
+
+out_unregister:
+	idle_inject_unregister(ii_dev);
+out_id:
+	ida_simple_remove(&cpuidle_ida, id);
+out_kfree:
+	kfree(idle_cdev);
+out:
+	return ret;
+}
+
+/**
+ * cpuidle_cooling_register - Idle cooling device initialization function
+ * @drv: a cpuidle driver structure pointer
+ *
+ * This function is in charge of creating a cooling device per cpuidle
+ * driver and register it to the thermal framework.
+ *
+ * Return: zero on success, or negative value corresponding to the
+ * error detected in the underlying subsystems.
+ */
+void cpuidle_cooling_register(struct cpuidle_driver *drv)
+{
+	struct device_node *cooling_node;
+	struct device_node *cpu_node;
+	int cpu, ret;
+
+	for_each_cpu(cpu, drv->cpumask) {
+
+		cpu_node = of_cpu_device_node_get(cpu);
+
+		cooling_node = of_get_child_by_name(cpu_node, "thermal-idle");
+
+		of_node_put(cpu_node);
+
+		if (!cooling_node) {
+			pr_debug("'thermal-idle' node not found for cpu%d\n", cpu);
+			continue;
+		}
+
+		ret = __cpuidle_cooling_register(cooling_node, drv);
+
+		of_node_put(cooling_node);
+
+		if (ret) {
+			pr_err("Failed to register the cpuidle cooling device" \
+			       "for cpu%d: %d\n", cpu, ret);
+			break;
+		}
+	}
+}