--- /dev/null
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2019 Linaro Limited.
+ *
+ * Author: Daniel Lezcano <daniel.lezcano@linaro.org>
+ *
+ */
+#include <linux/cpu_cooling.h>
+#include <linux/cpuidle.h>
+#include <linux/err.h>
+#include <linux/idle_inject.h>
+#include <linux/idr.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: the idle cooling device
+ * @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_of_cooling_register - Idle cooling device initialization function
+ * @drv: a cpuidle driver structure pointer
+ * @np: a node pointer to a device tree cooling device node
+ *
+ * This function is in charge of creating a cooling device per cpuidle
+ * driver and register it to thermal framework.
+ *
+ * Return: zero on success, or negative value corresponding to the
+ * error detected in the underlying subsystems.
+ */
+int cpuidle_of_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;
+ 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;
+ }
+
+ idle_inject_set_duration(ii_dev, TICK_USEC, TICK_USEC);
+
+ 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;
+ }
+
+ 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 thermal framework.
+ *
+ * Return: zero on success, or negative value corresponding to the
+ * error detected in the underlying subsystems.
+ */
+int cpuidle_cooling_register(struct cpuidle_driver *drv)
+{
+ return cpuidle_of_cooling_register(NULL, drv);
+}
projects / linux-2.6-microblaze.git / commitdiff