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path: root/drivers/devfreq/exynos-bus.c
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Diffstat (limited to 'drivers/devfreq/exynos-bus.c')
-rw-r--r--drivers/devfreq/exynos-bus.c570
1 files changed, 570 insertions, 0 deletions
diff --git a/drivers/devfreq/exynos-bus.c b/drivers/devfreq/exynos-bus.c
new file mode 100644
index 000000000..2363d0a18
--- /dev/null
+++ b/drivers/devfreq/exynos-bus.c
@@ -0,0 +1,570 @@
+/*
+ * Generic Exynos Bus frequency driver with DEVFREQ Framework
+ *
+ * Copyright (c) 2016 Samsung Electronics Co., Ltd.
+ * Author : Chanwoo Choi <cw00.choi@samsung.com>
+ *
+ * This driver support Exynos Bus frequency feature by using
+ * DEVFREQ framework and is based on drivers/devfreq/exynos/exynos4_bus.c.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include <linux/clk.h>
+#include <linux/devfreq.h>
+#include <linux/devfreq-event.h>
+#include <linux/device.h>
+#include <linux/export.h>
+#include <linux/module.h>
+#include <linux/of_device.h>
+#include <linux/pm_opp.h>
+#include <linux/platform_device.h>
+#include <linux/regulator/consumer.h>
+#include <linux/slab.h>
+
+#define DEFAULT_SATURATION_RATIO 40
+#define DEFAULT_VOLTAGE_TOLERANCE 2
+
+struct exynos_bus {
+ struct device *dev;
+
+ struct devfreq *devfreq;
+ struct devfreq_event_dev **edev;
+ unsigned int edev_count;
+ struct mutex lock;
+
+ struct dev_pm_opp *curr_opp;
+
+ struct regulator *regulator;
+ struct clk *clk;
+ unsigned int voltage_tolerance;
+ unsigned int ratio;
+};
+
+/*
+ * Control the devfreq-event device to get the current state of bus
+ */
+#define exynos_bus_ops_edev(ops) \
+static int exynos_bus_##ops(struct exynos_bus *bus) \
+{ \
+ int i, ret; \
+ \
+ for (i = 0; i < bus->edev_count; i++) { \
+ if (!bus->edev[i]) \
+ continue; \
+ ret = devfreq_event_##ops(bus->edev[i]); \
+ if (ret < 0) \
+ return ret; \
+ } \
+ \
+ return 0; \
+}
+exynos_bus_ops_edev(enable_edev);
+exynos_bus_ops_edev(disable_edev);
+exynos_bus_ops_edev(set_event);
+
+static int exynos_bus_get_event(struct exynos_bus *bus,
+ struct devfreq_event_data *edata)
+{
+ struct devfreq_event_data event_data;
+ unsigned long load_count = 0, total_count = 0;
+ int i, ret = 0;
+
+ for (i = 0; i < bus->edev_count; i++) {
+ if (!bus->edev[i])
+ continue;
+
+ ret = devfreq_event_get_event(bus->edev[i], &event_data);
+ if (ret < 0)
+ return ret;
+
+ if (i == 0 || event_data.load_count > load_count) {
+ load_count = event_data.load_count;
+ total_count = event_data.total_count;
+ }
+ }
+
+ edata->load_count = load_count;
+ edata->total_count = total_count;
+
+ return ret;
+}
+
+/*
+ * Must necessary function for devfreq simple-ondemand governor
+ */
+static int exynos_bus_target(struct device *dev, unsigned long *freq, u32 flags)
+{
+ struct exynos_bus *bus = dev_get_drvdata(dev);
+ struct dev_pm_opp *new_opp;
+ unsigned long old_freq, new_freq, old_volt, new_volt, tol;
+ int ret = 0;
+
+ /* Get new opp-bus instance according to new bus clock */
+ rcu_read_lock();
+ new_opp = devfreq_recommended_opp(dev, freq, flags);
+ if (IS_ERR(new_opp)) {
+ dev_err(dev, "failed to get recommended opp instance\n");
+ rcu_read_unlock();
+ return PTR_ERR(new_opp);
+ }
+
+ new_freq = dev_pm_opp_get_freq(new_opp);
+ new_volt = dev_pm_opp_get_voltage(new_opp);
+ old_freq = dev_pm_opp_get_freq(bus->curr_opp);
+ old_volt = dev_pm_opp_get_voltage(bus->curr_opp);
+ rcu_read_unlock();
+
+ if (old_freq == new_freq)
+ return 0;
+ tol = new_volt * bus->voltage_tolerance / 100;
+
+ /* Change voltage and frequency according to new OPP level */
+ mutex_lock(&bus->lock);
+
+ if (old_freq < new_freq) {
+ ret = regulator_set_voltage_tol(bus->regulator, new_volt, tol);
+ if (ret < 0) {
+ dev_err(bus->dev, "failed to set voltage\n");
+ goto out;
+ }
+ }
+
+ ret = clk_set_rate(bus->clk, new_freq);
+ if (ret < 0) {
+ dev_err(dev, "failed to change clock of bus\n");
+ clk_set_rate(bus->clk, old_freq);
+ goto out;
+ }
+
+ if (old_freq > new_freq) {
+ ret = regulator_set_voltage_tol(bus->regulator, new_volt, tol);
+ if (ret < 0) {
+ dev_err(bus->dev, "failed to set voltage\n");
+ goto out;
+ }
+ }
+ bus->curr_opp = new_opp;
+
+ dev_dbg(dev, "Set the frequency of bus (%lukHz -> %lukHz)\n",
+ old_freq/1000, new_freq/1000);
+out:
+ mutex_unlock(&bus->lock);
+
+ return ret;
+}
+
+static int exynos_bus_get_dev_status(struct device *dev,
+ struct devfreq_dev_status *stat)
+{
+ struct exynos_bus *bus = dev_get_drvdata(dev);
+ struct devfreq_event_data edata;
+ int ret;
+
+ rcu_read_lock();
+ stat->current_frequency = dev_pm_opp_get_freq(bus->curr_opp);
+ rcu_read_unlock();
+
+ ret = exynos_bus_get_event(bus, &edata);
+ if (ret < 0) {
+ stat->total_time = stat->busy_time = 0;
+ goto err;
+ }
+
+ stat->busy_time = (edata.load_count * 100) / bus->ratio;
+ stat->total_time = edata.total_count;
+
+ dev_dbg(dev, "Usage of devfreq-event : %lu/%lu\n", stat->busy_time,
+ stat->total_time);
+
+err:
+ ret = exynos_bus_set_event(bus);
+ if (ret < 0) {
+ dev_err(dev, "failed to set event to devfreq-event devices\n");
+ return ret;
+ }
+
+ return ret;
+}
+
+static void exynos_bus_exit(struct device *dev)
+{
+ struct exynos_bus *bus = dev_get_drvdata(dev);
+ int ret;
+
+ ret = exynos_bus_disable_edev(bus);
+ if (ret < 0)
+ dev_warn(dev, "failed to disable the devfreq-event devices\n");
+
+ if (bus->regulator)
+ regulator_disable(bus->regulator);
+
+ dev_pm_opp_of_remove_table(dev);
+ clk_disable_unprepare(bus->clk);
+}
+
+/*
+ * Must necessary function for devfreq passive governor
+ */
+static int exynos_bus_passive_target(struct device *dev, unsigned long *freq,
+ u32 flags)
+{
+ struct exynos_bus *bus = dev_get_drvdata(dev);
+ struct dev_pm_opp *new_opp;
+ unsigned long old_freq, new_freq;
+ int ret = 0;
+
+ /* Get new opp-bus instance according to new bus clock */
+ rcu_read_lock();
+ new_opp = devfreq_recommended_opp(dev, freq, flags);
+ if (IS_ERR(new_opp)) {
+ dev_err(dev, "failed to get recommended opp instance\n");
+ rcu_read_unlock();
+ return PTR_ERR(new_opp);
+ }
+
+ new_freq = dev_pm_opp_get_freq(new_opp);
+ old_freq = dev_pm_opp_get_freq(bus->curr_opp);
+ rcu_read_unlock();
+
+ if (old_freq == new_freq)
+ return 0;
+
+ /* Change the frequency according to new OPP level */
+ mutex_lock(&bus->lock);
+
+ ret = clk_set_rate(bus->clk, new_freq);
+ if (ret < 0) {
+ dev_err(dev, "failed to set the clock of bus\n");
+ goto out;
+ }
+
+ *freq = new_freq;
+ bus->curr_opp = new_opp;
+
+ dev_dbg(dev, "Set the frequency of bus (%lukHz -> %lukHz)\n",
+ old_freq/1000, new_freq/1000);
+out:
+ mutex_unlock(&bus->lock);
+
+ return ret;
+}
+
+static void exynos_bus_passive_exit(struct device *dev)
+{
+ struct exynos_bus *bus = dev_get_drvdata(dev);
+
+ dev_pm_opp_of_remove_table(dev);
+ clk_disable_unprepare(bus->clk);
+}
+
+static int exynos_bus_parent_parse_of(struct device_node *np,
+ struct exynos_bus *bus)
+{
+ struct device *dev = bus->dev;
+ int i, ret, count, size;
+
+ /* Get the regulator to provide each bus with the power */
+ bus->regulator = devm_regulator_get(dev, "vdd");
+ if (IS_ERR(bus->regulator)) {
+ dev_err(dev, "failed to get VDD regulator\n");
+ return PTR_ERR(bus->regulator);
+ }
+
+ ret = regulator_enable(bus->regulator);
+ if (ret < 0) {
+ dev_err(dev, "failed to enable VDD regulator\n");
+ return ret;
+ }
+
+ /*
+ * Get the devfreq-event devices to get the current utilization of
+ * buses. This raw data will be used in devfreq ondemand governor.
+ */
+ count = devfreq_event_get_edev_count(dev);
+ if (count < 0) {
+ dev_err(dev, "failed to get the count of devfreq-event dev\n");
+ ret = count;
+ goto err_regulator;
+ }
+ bus->edev_count = count;
+
+ size = sizeof(*bus->edev) * count;
+ bus->edev = devm_kzalloc(dev, size, GFP_KERNEL);
+ if (!bus->edev) {
+ ret = -ENOMEM;
+ goto err_regulator;
+ }
+
+ for (i = 0; i < count; i++) {
+ bus->edev[i] = devfreq_event_get_edev_by_phandle(dev, i);
+ if (IS_ERR(bus->edev[i])) {
+ ret = -EPROBE_DEFER;
+ goto err_regulator;
+ }
+ }
+
+ /*
+ * Optionally, Get the saturation ratio according to Exynos SoC
+ * When measuring the utilization of each AXI bus with devfreq-event
+ * devices, the measured real cycle might be much lower than the
+ * total cycle of bus during sampling rate. In result, the devfreq
+ * simple-ondemand governor might not decide to change the current
+ * frequency due to too utilization (= real cycle/total cycle).
+ * So, this property is used to adjust the utilization when calculating
+ * the busy_time in exynos_bus_get_dev_status().
+ */
+ if (of_property_read_u32(np, "exynos,saturation-ratio", &bus->ratio))
+ bus->ratio = DEFAULT_SATURATION_RATIO;
+
+ if (of_property_read_u32(np, "exynos,voltage-tolerance",
+ &bus->voltage_tolerance))
+ bus->voltage_tolerance = DEFAULT_VOLTAGE_TOLERANCE;
+
+ return 0;
+
+err_regulator:
+ regulator_disable(bus->regulator);
+
+ return ret;
+}
+
+static int exynos_bus_parse_of(struct device_node *np,
+ struct exynos_bus *bus)
+{
+ struct device *dev = bus->dev;
+ unsigned long rate;
+ int ret;
+
+ /* Get the clock to provide each bus with source clock */
+ bus->clk = devm_clk_get(dev, "bus");
+ if (IS_ERR(bus->clk)) {
+ dev_err(dev, "failed to get bus clock\n");
+ return PTR_ERR(bus->clk);
+ }
+
+ ret = clk_prepare_enable(bus->clk);
+ if (ret < 0) {
+ dev_err(dev, "failed to get enable clock\n");
+ return ret;
+ }
+
+ /* Get the freq and voltage from OPP table to scale the bus freq */
+ rcu_read_lock();
+ ret = dev_pm_opp_of_add_table(dev);
+ if (ret < 0) {
+ dev_err(dev, "failed to get OPP table\n");
+ rcu_read_unlock();
+ goto err_clk;
+ }
+
+ rate = clk_get_rate(bus->clk);
+ bus->curr_opp = devfreq_recommended_opp(dev, &rate, 0);
+ if (IS_ERR(bus->curr_opp)) {
+ dev_err(dev, "failed to find dev_pm_opp\n");
+ rcu_read_unlock();
+ ret = PTR_ERR(bus->curr_opp);
+ goto err_opp;
+ }
+ rcu_read_unlock();
+
+ return 0;
+
+err_opp:
+ dev_pm_opp_of_remove_table(dev);
+err_clk:
+ clk_disable_unprepare(bus->clk);
+
+ return ret;
+}
+
+static int exynos_bus_probe(struct platform_device *pdev)
+{
+ struct device *dev = &pdev->dev;
+ struct device_node *np = dev->of_node;
+ struct devfreq_dev_profile *profile;
+ struct devfreq_simple_ondemand_data *ondemand_data;
+ struct devfreq_passive_data *passive_data;
+ struct devfreq *parent_devfreq;
+ struct exynos_bus *bus;
+ int ret, max_state;
+ unsigned long min_freq, max_freq;
+
+ if (!np) {
+ dev_err(dev, "failed to find devicetree node\n");
+ return -EINVAL;
+ }
+
+ bus = devm_kzalloc(&pdev->dev, sizeof(*bus), GFP_KERNEL);
+ if (!bus)
+ return -ENOMEM;
+ mutex_init(&bus->lock);
+ bus->dev = &pdev->dev;
+ platform_set_drvdata(pdev, bus);
+
+ /* Parse the device-tree to get the resource information */
+ ret = exynos_bus_parse_of(np, bus);
+ if (ret < 0)
+ goto err;
+
+ profile = devm_kzalloc(dev, sizeof(*profile), GFP_KERNEL);
+ if (!profile) {
+ ret = -ENOMEM;
+ goto err;
+ }
+
+ if (of_parse_phandle(dev->of_node, "devfreq", 0))
+ goto passive;
+ else
+ ret = exynos_bus_parent_parse_of(np, bus);
+
+ if (ret < 0)
+ goto err;
+
+ /* Initialize the struct profile and governor data for parent device */
+ profile->polling_ms = 50;
+ profile->target = exynos_bus_target;
+ profile->get_dev_status = exynos_bus_get_dev_status;
+ profile->exit = exynos_bus_exit;
+
+ ondemand_data = devm_kzalloc(dev, sizeof(*ondemand_data), GFP_KERNEL);
+ if (!ondemand_data) {
+ ret = -ENOMEM;
+ goto err;
+ }
+ ondemand_data->upthreshold = 40;
+ ondemand_data->downdifferential = 5;
+
+ /* Add devfreq device to monitor and handle the exynos bus */
+ bus->devfreq = devm_devfreq_add_device(dev, profile, "simple_ondemand",
+ ondemand_data);
+ if (IS_ERR(bus->devfreq)) {
+ dev_err(dev, "failed to add devfreq device\n");
+ ret = PTR_ERR(bus->devfreq);
+ goto err;
+ }
+
+ /* Register opp_notifier to catch the change of OPP */
+ ret = devm_devfreq_register_opp_notifier(dev, bus->devfreq);
+ if (ret < 0) {
+ dev_err(dev, "failed to register opp notifier\n");
+ goto err;
+ }
+
+ /*
+ * Enable devfreq-event to get raw data which is used to determine
+ * current bus load.
+ */
+ ret = exynos_bus_enable_edev(bus);
+ if (ret < 0) {
+ dev_err(dev, "failed to enable devfreq-event devices\n");
+ goto err;
+ }
+
+ ret = exynos_bus_set_event(bus);
+ if (ret < 0) {
+ dev_err(dev, "failed to set event to devfreq-event devices\n");
+ goto err;
+ }
+
+ goto out;
+passive:
+ /* Initialize the struct profile and governor data for passive device */
+ profile->target = exynos_bus_passive_target;
+ profile->exit = exynos_bus_passive_exit;
+
+ /* Get the instance of parent devfreq device */
+ parent_devfreq = devfreq_get_devfreq_by_phandle(dev, 0);
+ if (IS_ERR(parent_devfreq)) {
+ ret = -EPROBE_DEFER;
+ goto err;
+ }
+
+ passive_data = devm_kzalloc(dev, sizeof(*passive_data), GFP_KERNEL);
+ if (!passive_data) {
+ ret = -ENOMEM;
+ goto err;
+ }
+ passive_data->parent = parent_devfreq;
+
+ /* Add devfreq device for exynos bus with passive governor */
+ bus->devfreq = devm_devfreq_add_device(dev, profile, "passive",
+ passive_data);
+ if (IS_ERR(bus->devfreq)) {
+ dev_err(dev,
+ "failed to add devfreq dev with passive governor\n");
+ ret = -EPROBE_DEFER;
+ goto err;
+ }
+
+out:
+ max_state = bus->devfreq->profile->max_state;
+ min_freq = (bus->devfreq->profile->freq_table[0] / 1000);
+ max_freq = (bus->devfreq->profile->freq_table[max_state - 1] / 1000);
+ pr_info("exynos-bus: new bus device registered: %s (%6ld KHz ~ %6ld KHz)\n",
+ dev_name(dev), min_freq, max_freq);
+
+ return 0;
+
+err:
+ dev_pm_opp_of_remove_table(dev);
+ clk_disable_unprepare(bus->clk);
+
+ return ret;
+}
+
+#ifdef CONFIG_PM_SLEEP
+static int exynos_bus_resume(struct device *dev)
+{
+ struct exynos_bus *bus = dev_get_drvdata(dev);
+ int ret;
+
+ ret = exynos_bus_enable_edev(bus);
+ if (ret < 0) {
+ dev_err(dev, "failed to enable the devfreq-event devices\n");
+ return ret;
+ }
+
+ return 0;
+}
+
+static int exynos_bus_suspend(struct device *dev)
+{
+ struct exynos_bus *bus = dev_get_drvdata(dev);
+ int ret;
+
+ ret = exynos_bus_disable_edev(bus);
+ if (ret < 0) {
+ dev_err(dev, "failed to disable the devfreq-event devices\n");
+ return ret;
+ }
+
+ return 0;
+}
+#endif
+
+static const struct dev_pm_ops exynos_bus_pm = {
+ SET_SYSTEM_SLEEP_PM_OPS(exynos_bus_suspend, exynos_bus_resume)
+};
+
+static const struct of_device_id exynos_bus_of_match[] = {
+ { .compatible = "samsung,exynos-bus", },
+ { /* sentinel */ },
+};
+MODULE_DEVICE_TABLE(of, exynos_bus_of_match);
+
+static struct platform_driver exynos_bus_platdrv = {
+ .probe = exynos_bus_probe,
+ .driver = {
+ .name = "exynos-bus",
+ .pm = &exynos_bus_pm,
+ .of_match_table = of_match_ptr(exynos_bus_of_match),
+ },
+};
+module_platform_driver(exynos_bus_platdrv);
+
+MODULE_DESCRIPTION("Generic Exynos Bus frequency driver");
+MODULE_AUTHOR("Chanwoo Choi <cw00.choi@samsung.com>");
+MODULE_LICENSE("GPL v2");