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Subject[PATCH RFC 5/9] PM / devfreq: Add devfreq driver for interconnect bandwidth voting
Date
From: Saravana Kannan <skannan@codeaurora.org>

This driver registers itself as a devfreq device that allows devfreq
governors to make bandwidth votes for an interconnect path. This allows
applying various policies for different interconnect paths using devfreq
governors.

Example uses:
* Use the devfreq performance governor to set the CPU to DDR
interconnect path for maximum performance.
* Use the devfreq powersave governor to set the GPU to DDR
interconnect path for minimum performance.
* Use the Passive governor to scale the DDR frequency based
on the needs of the CPUs' current frequency

Signed-off-by: Saravana Kannan <skannan@codeaurora.org>
[Sibi: cleanup and added passive governor support]
Signed-off-by: Sibi Sankar <sibis@codeaurora.org>
---
drivers/devfreq/Kconfig | 15 ++++
drivers/devfreq/Makefile | 1 +
drivers/devfreq/devfreq_icbw.c | 132 +++++++++++++++++++++++++++++++++
3 files changed, 148 insertions(+)
create mode 100644 drivers/devfreq/devfreq_icbw.c

diff --git a/drivers/devfreq/Kconfig b/drivers/devfreq/Kconfig
index 9a45f464a56b..0df5b65f157a 100644
--- a/drivers/devfreq/Kconfig
+++ b/drivers/devfreq/Kconfig
@@ -117,6 +117,21 @@ config ARM_RK3399_DMC_DEVFREQ
It sets the frequency for the memory controller and reads the usage counts
from hardware.

+config DEVFREQ_ICBW
+ tristate "Driver for making bandwidth votes on interconnect paths"
+ select DEVFREQ_GOV_PASSIVE
+ select DEVFREQ_GOV_PERFORMANCE
+ select DEVFREQ_GOV_POWERSAVE
+ select DEVFREQ_GOV_USERSPACE
+ depends on INTERCONNECT
+ default n
+ help
+ Different devfreq governors use this devfreq device to make
+ bandwidth votes for interconnect paths between different devices
+ (Eg: CPU to DDR, GPU to DDR, etc). This driver provides a generic
+ interface so that the devfreq governors can be shared across SoCs
+ and architectures.
+
source "drivers/devfreq/event/Kconfig"

endif # PM_DEVFREQ
diff --git a/drivers/devfreq/Makefile b/drivers/devfreq/Makefile
index 32b8d4d3f12c..66591b0e5259 100644
--- a/drivers/devfreq/Makefile
+++ b/drivers/devfreq/Makefile
@@ -11,6 +11,7 @@ obj-$(CONFIG_DEVFREQ_GOV_PASSIVE) += governor_passive.o
obj-$(CONFIG_ARM_EXYNOS_BUS_DEVFREQ) += exynos-bus.o
obj-$(CONFIG_ARM_RK3399_DMC_DEVFREQ) += rk3399_dmc.o
obj-$(CONFIG_ARM_TEGRA_DEVFREQ) += tegra-devfreq.o
+obj-$(CONFIG_DEVFREQ_ICBW) += devfreq_icbw.o

# DEVFREQ Event Drivers
obj-$(CONFIG_PM_DEVFREQ_EVENT) += event/
diff --git a/drivers/devfreq/devfreq_icbw.c b/drivers/devfreq/devfreq_icbw.c
new file mode 100644
index 000000000000..c552cf4218c8
--- /dev/null
+++ b/drivers/devfreq/devfreq_icbw.c
@@ -0,0 +1,132 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (c) 2018, The Linux Foundation. All rights reserved.
+ */
+
+#include <linux/devfreq.h>
+#include <linux/interconnect.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+
+struct icbw_data {
+ struct devfreq *df;
+ struct icc_path *path;
+ u32 cur_ab;
+ u32 cur_pb;
+};
+
+static int icbw_target(struct device *dev, unsigned long *freq, u32 flags)
+{
+ struct dev_pm_opp *opp;
+ struct icbw_data *data = dev_get_drvdata(dev);
+ u32 new_pb, new_ab;
+ int ret;
+
+ opp = devfreq_recommended_opp(dev, freq, flags);
+ if (IS_ERR(opp))
+ return PTR_ERR(opp);
+
+ /* Get avg and peak bandwidth */
+ new_ab = dev_pm_opp_get_avg_bw(opp);
+ new_pb = dev_pm_opp_get_peak_bw(opp);
+ dev_pm_opp_put(opp);
+
+ if (data->cur_pb == new_pb && data->cur_ab == new_ab)
+ return 0;
+
+ dev_dbg(dev, "BW icc: AB: %u PB: %u\n", new_ab, new_pb);
+
+ ret = icc_set_bw(data->path, new_ab, new_pb);
+ if (ret) {
+ dev_err(dev, "bandwidth request failed (%d)\n", ret);
+ } else {
+ data->cur_pb = new_pb;
+ data->cur_ab = new_ab;
+ }
+
+ return ret;
+}
+
+static int devfreq_icbw_probe(struct platform_device *pdev)
+{
+ struct device *dev = &pdev->dev;
+ struct devfreq_dev_profile *profile;
+ struct devfreq_passive_data *passive_data;
+ struct icbw_data *data;
+ int ret;
+
+ data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
+ if (!data)
+ return -ENOMEM;
+ dev_set_drvdata(dev, data);
+
+ passive_data = devm_kzalloc(dev, sizeof(*passive_data), GFP_KERNEL);
+ if (!passive_data)
+ return -ENOMEM;
+
+ passive_data->cpufreq_type = true;
+
+ profile = devm_kzalloc(dev, sizeof(*profile), GFP_KERNEL);
+ if (!profile)
+ return -ENOMEM;
+
+ profile->target = icbw_target;
+
+ data->path = of_icc_get(dev, NULL);
+ if (IS_ERR(data->path)) {
+ dev_err(dev, "Unable to register interconnect path\n");
+ return PTR_ERR(data->path);
+ }
+
+ ret = dev_pm_opp_of_add_table(dev);
+ if (ret) {
+ dev_err(dev, "Couldn't find OPP table\n");
+ goto err_icc;
+ }
+
+ data->df = devfreq_add_device(dev, profile,
+ DEVFREQ_GOV_PASSIVE, passive_data);
+ if (IS_ERR(data->df)) {
+ ret = PTR_ERR(data->df);
+ goto err_opp_table;
+ }
+
+ return 0;
+
+err_opp_table:
+ dev_pm_opp_of_remove_table(dev);
+err_icc:
+ icc_put(data->path);
+ return ret;
+}
+
+static int devfreq_icbw_remove(struct platform_device *pdev)
+{
+ struct device *dev = &pdev->dev;
+ struct icbw_data *data = dev_get_drvdata(dev);
+
+ devfreq_remove_device(data->df);
+ icc_put(data->path);
+ return 0;
+}
+
+static const struct of_device_id icbw_match_table[] = {
+ { .compatible = "devfreq-icbw" },
+ {}
+};
+MODULE_DEVICE_TABLE(of, icbw_match_table);
+
+static struct platform_driver icbw_driver = {
+ .probe = devfreq_icbw_probe,
+ .remove = devfreq_icbw_remove,
+ .driver = {
+ .name = "devfreq-icbw",
+ .of_match_table = icbw_match_table,
+ },
+};
+module_platform_driver(icbw_driver);
+
+MODULE_DESCRIPTION("Interconnect bandwidth voting driver");
+MODULE_LICENSE("GPL v2");
--
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
a Linux Foundation Collaborative Project
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