[PATCH v2 01/19] PM / devfreq: exynos: Add generic exynos bus frequency driver

Chanwoo Choi
2015-12-09T04:08:22Z

This patch adds the generic exynos bus frequency driver for AMBA AXI bus
of sub-blocks in exynos SoC with DEVFREQ framework. The Samsung Exynos SoC
have the common architecture for bus between DRAM and sub-blocks in SoC.
This driver can support the generic bus frequency driver for Exynos SoCs.

In devicetree, Each bus block has a bus clock, regulator, operation-point
and devfreq-event devices which measure the utilization of each bus block.

Signed-off-by: Chanwoo Choi <cw00.choi@samsung.com>
---
drivers/devfreq/Kconfig | 15 ++
drivers/devfreq/Makefile | 1 +
drivers/devfreq/exynos/Makefile | 1 +
drivers/devfreq/exynos/exynos-bus.c | 449 ++++++++++++++++++++++++++++++++++++
4 files changed, 466 insertions(+)
create mode 100644 drivers/devfreq/exynos/exynos-bus.c

diff --git a/drivers/devfreq/Kconfig b/drivers/devfreq/Kconfig
index 64281bb2f650..55ec774f794c 100644
--- a/drivers/devfreq/Kconfig
+++ b/drivers/devfreq/Kconfig
@@ -66,6 +66,21 @@ config DEVFREQ_GOV_USERSPACE

comment "DEVFREQ Drivers"

+config ARM_EXYNOS_BUS_DEVFREQ
+ bool "ARM EXYNOS Generic Memory Bus DEVFREQ Driver"
+ depends on ARCH_EXYNOS
+ select DEVFREQ_GOV_SIMPLE_ONDEMAND
+ select DEVFREQ_EVENT_EXYNOS_PPMU
+ select PM_DEVFREQ_EVENT
+ select PM_OPP
+ help
+ This adds the common DEVFREQ driver for Exynos Memory bus. Exynos
+ Memory bus has one more group of memory bus (e.g, MIF and INT block).
+ Each memory bus group could contain many memoby bus block. It reads
+ PPMU counters of memory controllers by using DEVFREQ-event device
+ and adjusts the operating frequencies and voltages with OPP support.
+ This does not yet operate with optimal voltages.
+
config ARM_EXYNOS4_BUS_DEVFREQ
bool "ARM Exynos4210/4212/4412 Memory Bus DEVFREQ Driver"
depends on (CPU_EXYNOS4210 || SOC_EXYNOS4212 || SOC_EXYNOS4412) && !ARCH_MULTIPLATFORM
diff --git a/drivers/devfreq/Makefile b/drivers/devfreq/Makefile
index 5134f9ee983d..375ebbb4fcfb 100644
--- a/drivers/devfreq/Makefile
+++ b/drivers/devfreq/Makefile
@@ -6,6 +6,7 @@ obj-$(CONFIG_DEVFREQ_GOV_POWERSAVE) += governor_powersave.o
obj-$(CONFIG_DEVFREQ_GOV_USERSPACE) += governor_userspace.o

# DEVFREQ Drivers
+obj-$(CONFIG_ARCH_EXYNOS) += exynos/
obj-$(CONFIG_ARM_EXYNOS4_BUS_DEVFREQ) += exynos/
obj-$(CONFIG_ARM_EXYNOS5_BUS_DEVFREQ) += exynos/
obj-$(CONFIG_ARM_TEGRA_DEVFREQ) += tegra-devfreq.o
diff --git a/drivers/devfreq/exynos/Makefile b/drivers/devfreq/exynos/Makefile
index 49bc9175f923..4ec06d322996 100644
--- a/drivers/devfreq/exynos/Makefile
+++ b/drivers/devfreq/exynos/Makefile
@@ -1,3 +1,4 @@
# Exynos DEVFREQ Drivers
+obj-$(CONFIG_ARM_EXYNOS_BUS_DEVFREQ) += exynos-bus.o
obj-$(CONFIG_ARM_EXYNOS4_BUS_DEVFREQ) += exynos_ppmu.o exynos4_bus.o
obj-$(CONFIG_ARM_EXYNOS5_BUS_DEVFREQ) += exynos_ppmu.o exynos5_bus.o
diff --git a/drivers/devfreq/exynos/exynos-bus.c b/drivers/devfreq/exynos/exynos-bus.c
new file mode 100644
index 000000000000..f1bc20839650
--- /dev/null
+++ b/drivers/devfreq/exynos/exynos-bus.c
@@ -0,0 +1,449 @@
+/*
+ * Generic Exynos Bus frequency driver with DEVFREQ Framework
+ *
+ * Copyright (c) 2015 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
+
+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;
+ 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 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;
+ 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_OR_NULL(new_opp)) {
+ dev_err(dev, "failed to get recommed 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;
+
+ /* Change voltage and frequency according to new OPP level */
+ mutex_lock(&bus->lock);
+
+ if (old_freq < new_freq) {
+ ret = regulator_set_voltage(bus->regulator, new_volt, new_volt);
+ if (ret < 0) {
+ dev_err(bus->dev, "failed to set voltage\n");
+ regulator_set_voltage(bus->regulator, old_volt,
+ old_volt);
+ 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(bus->regulator, new_volt, new_volt);
+ if (ret < 0) {
+ dev_err(bus->dev, "failed to set voltage\n");
+ regulator_set_voltage(bus->regulator, old_volt,
+ old_volt);
+ goto out;
+ }
+ }
+ bus->curr_opp = new_opp;
+
+ dev_dbg(dev, "Set the frequency of bus (%ldkHz -> %ldkHz)\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 : %ld/%ld\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);
+}
+
+static int exynos_bus_parse_of(struct device_node *np,
+ struct exynos_bus *bus)
+{
+ struct device *dev = bus->dev;
+ unsigned long rate;
+ int i, ret, count, size;
+
+ /* 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/voltage OPP table to scale the bus frequency */
+ 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();
+ return ret;
+ }
+
+ rate = clk_get_rate(bus->clk);
+ bus->curr_opp = dev_pm_opp_find_freq_ceil(dev, &rate);
+ 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();
+
+ /* 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");
+ ret = PTR_ERR(bus->regulator);
+ goto err_opp;
+ }
+
+ ret = regulator_enable(bus->regulator);
+ if (ret < 0) {
+ dev_err(dev, "failed to enable VDD regulator\n");
+ goto err_opp;
+ }
+
+ /*
+ * 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;
+
+ return 0;
+
+err_regulator:
+ regulator_disable(bus->regulator);
+err_opp:
+ dev_pm_opp_of_remove_table(dev);
+
+ 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 exynos_bus *bus;
+ int ret;
+
+ 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)
+ return ret;
+
+ /* Initalize the struct profile and governor data */
+ profile = devm_kzalloc(dev, sizeof(*profile), GFP_KERNEL);
+ if (!profile)
+ return -ENOMEM;
+ 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)
+ return -ENOMEM;
+ 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_OR_NULL(bus->devfreq)) {
+ dev_err(dev, "failed to add devfreq device\n");
+ return PTR_ERR(bus->devfreq);
+ }
+
+ /* 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");
+ return ret;
+ }
+
+ /*
+ * 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");
+ return ret;
+ }
+
+ ret = exynos_bus_set_event(bus);
+ if (ret < 0) {
+ dev_err(dev, "failed to set event to devfreq-event devices\n");
+ return ret;
+ }
+
+ return 0;
+}
+
+#ifdef CONFIG_PM_SLEEP
+static int exynos_bus_resume(struct device *dev)
+{
+ struct exynos_bus *bus = dev_get_drvdata(dev);
+ int ret;
+
+ if (bus->regulator) {
+ ret = regulator_enable(bus->regulator);
+ if (ret < 0) {
+ dev_err(dev, "failed to enable VDD regulator\n");
+ return 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;
+ }
+
+ if (bus->regulator)
+ regulator_disable(bus->regulator);
+
+ 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");
--
1.9.1