ipq806x: switch to generic cpufreq driver cpufreq-dt

This fixes ondemand frequency scaling and moves ipq806x onto upstream driver

Also switching to ondemand frequency scaling as it is fixed now

Signed-off-by: Pavel Kubelun <be.dissent@gmail.com>

4 files changed, 378 insertions, 461 deletions

diff --git a/target/linux/ipq806x/patches-4.4/145-cpufreq-Add-a-cpufreq-krait-based-on-cpufre.patch b/target/linux/ipq806x/patches-4.4/145-cpufreq-Add-a-cpufreq-krait-based-on-cpufre.patch
deleted file mode 100644
index 67770e8..0000000
--- a/target/linux/ipq806x/patches-4.4/145-cpufreq-Add-a-cpufreq-krait-based-on-cpufre.patch
+++ /dev/null
@@ -1,461 +0,0 @@
-From dd77db4143290689d3a5e1ec61627233d0711b66 Mon Sep 17 00:00:00 2001
-From: Stephen Boyd <sboyd@codeaurora.org>
-Date: Fri, 30 May 2014 16:36:11 -0700
-Subject: [PATCH] FROMLIST: cpufreq: Add a cpufreq-krait based on cpufreq-cpu0
-
-Krait processors have individual clocks for each CPU that can
-scale independently from one another. cpufreq-cpu0 is fairly
-close to this, but assumes that there is only one clock for all
-CPUs. Add a driver to support the Krait configuration.
-
-TODO: Merge into cpufreq-cpu0? Or make generic?
-
-Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
-
----
- drivers/cpufreq/Kconfig         |  13 +++
- drivers/cpufreq/Makefile        |   1 +
- drivers/cpufreq/cpufreq-krait.c | 190 ++++++++++++++++++++++++++++++++++++++++
- 3 files changed, 204 insertions(+)
- create mode 100644 drivers/cpufreq/cpufreq-krait.c
-
---- a/drivers/cpufreq/Kconfig
-+++ b/drivers/cpufreq/Kconfig
-@@ -198,6 +198,19 @@ config CPUFREQ_DT
- 
- 	  If in doubt, say N.
- 
-+config GENERIC_CPUFREQ_KRAIT
-+	tristate "Krait cpufreq driver"
-+	depends on HAVE_CLK && OF
-+	# if CPU_THERMAL is on and THERMAL=m, CPU0 cannot be =y:
-+	depends on !CPU_THERMAL || THERMAL
-+	select PM_OPP
-+	help
-+	  This adds a generic cpufreq driver for CPU0 frequency management.
-+	  It supports both uniprocessor (UP) and symmetric multiprocessor (SMP)
-+	  systems which share clock and voltage across all CPUs.
-+
-+	  If in doubt, say N.
-+
- if X86
- source "drivers/cpufreq/Kconfig.x86"
- endif
---- a/drivers/cpufreq/Makefile
-+++ b/drivers/cpufreq/Makefile
-@@ -13,6 +13,7 @@ obj-$(CONFIG_CPU_FREQ_GOV_CONSERVATIVE)
- obj-$(CONFIG_CPU_FREQ_GOV_COMMON)		+= cpufreq_governor.o
- 
- obj-$(CONFIG_CPUFREQ_DT)		+= cpufreq-dt.o
-+obj-$(CONFIG_GENERIC_CPUFREQ_KRAIT)    += cpufreq-krait.o
- 
- ##################################################################################
- # x86 drivers.
---- /dev/null
-+++ b/drivers/cpufreq/cpufreq-krait.c
-@@ -0,0 +1,390 @@
-+/*
-+ * Copyright (C) 2012 Freescale Semiconductor, Inc.
-+ * Copyright (c) 2014, The Linux Foundation. All rights reserved.
-+ *
-+ * The OPP code in function krait_set_target() is reused from
-+ * drivers/cpufreq/omap-cpufreq.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/cpu.h>
-+#include <linux/cpu_cooling.h>
-+#include <linux/cpufreq.h>
-+#include <linux/cpumask.h>
-+#include <linux/err.h>
-+#include <linux/module.h>
-+#include <linux/of.h>
-+#include <linux/pm_opp.h>
-+#include <linux/platform_device.h>
-+#include <linux/regulator/consumer.h>
-+#include <linux/slab.h>
-+#include <linux/thermal.h>
-+
-+static unsigned int transition_latency;
-+static unsigned int voltage_tolerance; /* in percentage */
-+
-+static struct device *cpu_dev;
-+static DEFINE_PER_CPU(struct clk *, krait_cpu_clks);
-+static DEFINE_PER_CPU(struct regulator *, krait_supply_core);
-+static struct cpufreq_frequency_table *freq_table;
-+static struct thermal_cooling_device *cdev;
-+
-+struct cache_points {
-+	unsigned long cache_freq;
-+	unsigned int cache_volt;
-+	unsigned long cpu_freq;
-+};
-+
-+static struct regulator *krait_l2_reg;
-+static struct clk *krait_l2_clk;
-+static struct cache_points *krait_l2_points;
-+static int nr_krait_l2_points;
-+
-+static int krait_parse_cache_points(struct device *dev,
-+		struct device_node *of_node)
-+{
-+	const struct property *prop;
-+	const __be32 *val;
-+	int nr, i;
-+
-+	prop = of_find_property(of_node, "cache-points-kHz", NULL);
-+	if (!prop)
-+		return -ENODEV;
-+	if (!prop->value)
-+		return -ENODATA;
-+
-+	/*
-+	 * Each OPP is a set of tuples consisting of frequency and
-+	 * cpu-frequency like <freq-kHz volt-uV freq-kHz>.
-+	 */
-+	nr = prop->length / sizeof(u32);
-+	if (nr % 3) {
-+		dev_err(dev, "%s: Invalid cache points\n", __func__);
-+		return -EINVAL;
-+	}
-+	nr /= 3;
-+
-+	krait_l2_points = devm_kcalloc(dev, nr, sizeof(*krait_l2_points),
-+				       GFP_KERNEL);
-+	if (!krait_l2_points)
-+		return -ENOMEM;
-+	nr_krait_l2_points = nr;
-+
-+	for (i = 0, val = prop->value; i < nr; i++) {
-+		unsigned long cache_freq = be32_to_cpup(val++) * 1000;
-+		unsigned int cache_volt = be32_to_cpup(val++);
-+		unsigned long cpu_freq = be32_to_cpup(val++) * 1000;
-+
-+		krait_l2_points[i].cache_freq = cache_freq;
-+		krait_l2_points[i].cache_volt = cache_volt;
-+		krait_l2_points[i].cpu_freq = cpu_freq;
-+	}
-+
-+	return 0;
-+}
-+
-+static int krait_set_target(struct cpufreq_policy *policy, unsigned int index)
-+{
-+	struct dev_pm_opp *opp;
-+	unsigned long volt = 0, volt_old = 0, tol = 0;
-+	unsigned long freq, max_cpu_freq = 0;
-+	unsigned int old_freq, new_freq;
-+	long freq_Hz, freq_exact;
-+	int ret, i;
-+	struct clk *cpu_clk;
-+	struct regulator *core;
-+	unsigned int cpu;
-+
-+	cpu_clk = per_cpu(krait_cpu_clks, policy->cpu);
-+
-+	freq_Hz = clk_round_rate(cpu_clk, freq_table[index].frequency * 1000);
-+	if (freq_Hz <= 0)
-+		freq_Hz = freq_table[index].frequency * 1000;
-+
-+	freq_exact = freq_Hz;
-+	new_freq = freq_Hz / 1000;
-+	old_freq = clk_get_rate(cpu_clk) / 1000;
-+
-+	core = per_cpu(krait_supply_core, policy->cpu);
-+
-+	rcu_read_lock();
-+	opp = dev_pm_opp_find_freq_ceil(cpu_dev, &freq_Hz);
-+	if (IS_ERR(opp)) {
-+		rcu_read_unlock();
-+		pr_err("failed to find OPP for %ld\n", freq_Hz);
-+		return PTR_ERR(opp);
-+	}
-+	volt = dev_pm_opp_get_voltage(opp);
-+	rcu_read_unlock();
-+	tol = volt * voltage_tolerance / 100;
-+	volt_old = regulator_get_voltage(core);
-+
-+	pr_debug("%u MHz, %ld mV --> %u MHz, %ld mV\n",
-+		 old_freq / 1000, volt_old ? volt_old / 1000 : -1,
-+		 new_freq / 1000, volt ? volt / 1000 : -1);
-+
-+	/* scaling up?  scale voltage before frequency */
-+	if (new_freq > old_freq) {
-+		ret = regulator_set_voltage_tol(core, volt, tol);
-+		if (ret) {
-+			pr_err("failed to scale voltage up: %d\n", ret);
-+			return ret;
-+		}
-+	}
-+
-+	ret = clk_set_rate(cpu_clk, freq_exact);
-+	if (ret) {
-+		pr_err("failed to set clock rate: %d\n", ret);
-+		return ret;
-+	}
-+
-+	/* scaling down?  scale voltage after frequency */
-+	if (new_freq < old_freq) {
-+		ret = regulator_set_voltage_tol(core, volt, tol);
-+		if (ret) {
-+			pr_err("failed to scale voltage down: %d\n", ret);
-+			clk_set_rate(cpu_clk, old_freq * 1000);
-+		}
-+	}
-+
-+	for_each_possible_cpu(cpu) {
-+		freq = clk_get_rate(per_cpu(krait_cpu_clks, cpu));
-+		max_cpu_freq = max(max_cpu_freq, freq);
-+	}
-+
-+	for (i = 0; i < nr_krait_l2_points; i++) {
-+		if (max_cpu_freq >= krait_l2_points[i].cpu_freq) {
-+			if (krait_l2_reg) {
-+				ret = regulator_set_voltage_tol(krait_l2_reg,
-+						krait_l2_points[i].cache_volt,
-+						tol);
-+				if (ret) {
-+					pr_err("failed to scale l2 voltage: %d\n",
-+						ret);
-+				}
-+			}
-+			ret = clk_set_rate(krait_l2_clk,
-+					krait_l2_points[i].cache_freq);
-+			if (ret)
-+				pr_err("failed to scale l2 clk: %d\n", ret);
-+			break;
-+		}
-+
-+	}
-+
-+	return ret;
-+}
-+
-+static int krait_cpufreq_init(struct cpufreq_policy *policy)
-+{
-+	int ret;
-+
-+	policy->clk = per_cpu(krait_cpu_clks, policy->cpu);
-+
-+	ret = cpufreq_table_validate_and_show(policy, freq_table);
-+	if (ret) {
-+		pr_err("%s: invalid frequency table: %d\n", __func__, ret);
-+		return ret;
-+	}
-+
-+	policy->cpuinfo.transition_latency = transition_latency;
-+
-+	return 0;
-+}
-+
-+static struct cpufreq_driver krait_cpufreq_driver = {
-+	.flags = CPUFREQ_STICKY,
-+	.verify = cpufreq_generic_frequency_table_verify,
-+	.target_index = krait_set_target,
-+	.get = cpufreq_generic_get,
-+	.init = krait_cpufreq_init,
-+	.name = "generic_krait",
-+	.attr = cpufreq_generic_attr,
-+};
-+
-+static int krait_cpufreq_probe(struct platform_device *pdev)
-+{
-+	struct device_node *np, *cache;
-+	int ret, i;
-+	unsigned int cpu;
-+	struct device *dev;
-+	struct clk *clk;
-+	struct regulator *core;
-+	unsigned long freq_Hz, freq, max_cpu_freq = 0;
-+	struct dev_pm_opp *opp;
-+	unsigned long volt, tol;
-+
-+	cpu_dev = get_cpu_device(0);
-+	if (!cpu_dev) {
-+		pr_err("failed to get krait device\n");
-+		return -ENODEV;
-+	}
-+
-+	np = of_node_get(cpu_dev->of_node);
-+	if (!np) {
-+		pr_err("failed to find krait node\n");
-+		return -ENOENT;
-+	}
-+
-+	ret = dev_pm_opp_init_cpufreq_table(cpu_dev, &freq_table);
-+	if (ret) {
-+		pr_err("failed to init cpufreq table: %d\n", ret);
-+		goto out_put_node;
-+	}
-+
-+	of_property_read_u32(np, "voltage-tolerance", &voltage_tolerance);
-+
-+	if (of_property_read_u32(np, "clock-latency", &transition_latency))
-+		transition_latency = CPUFREQ_ETERNAL;
-+
-+	cache = of_find_next_cache_node(np);
-+	if (cache) {
-+		struct device_node *vdd;
-+
-+		vdd = of_parse_phandle(cache, "vdd_dig-supply", 0);
-+		if (vdd) {
-+			krait_l2_reg = regulator_get(NULL, vdd->name);
-+			if (IS_ERR(krait_l2_reg)) {
-+				pr_warn("failed to get l2 vdd_dig supply\n");
-+				krait_l2_reg = NULL;
-+			}
-+			of_node_put(vdd);
-+		}
-+
-+		krait_l2_clk = of_clk_get(cache, 0);
-+		if (!IS_ERR(krait_l2_clk)) {
-+			ret = krait_parse_cache_points(&pdev->dev, cache);
-+			if (ret)
-+				clk_put(krait_l2_clk);
-+		}
-+		if (IS_ERR(krait_l2_clk) || ret)
-+			krait_l2_clk = NULL;
-+	}
-+
-+	for_each_possible_cpu(cpu) {
-+		dev = get_cpu_device(cpu);
-+		if (!dev) {
-+			pr_err("failed to get krait device\n");
-+			ret = -ENOENT;
-+			goto out_free_table;
-+		}
-+		per_cpu(krait_cpu_clks, cpu) = clk = devm_clk_get(dev, NULL);
-+		if (IS_ERR(clk)) {
-+			ret = PTR_ERR(clk);
-+			goto out_free_table;
-+		}
-+		core = devm_regulator_get(dev, "core");
-+		if (IS_ERR(core)) {
-+			pr_debug("failed to get core regulator\n");
-+			ret = PTR_ERR(core);
-+			goto out_free_table;
-+		}
-+		per_cpu(krait_supply_core, cpu) = core;
-+
-+		freq = freq_Hz = clk_get_rate(clk);
-+
-+		rcu_read_lock();
-+		opp = dev_pm_opp_find_freq_ceil(cpu_dev, &freq_Hz);
-+		if (IS_ERR(opp)) {
-+			rcu_read_unlock();
-+			pr_err("failed to find OPP for %ld\n", freq_Hz);
-+			ret = PTR_ERR(opp);
-+			goto out_free_table;
-+		}
-+		volt = dev_pm_opp_get_voltage(opp);
-+		rcu_read_unlock();
-+
-+		tol = volt * voltage_tolerance / 100;
-+		ret = regulator_set_voltage_tol(core, volt, tol);
-+		if (ret) {
-+			pr_err("failed to scale voltage up: %d\n", ret);
-+			goto out_free_table;
-+		}
-+		ret = regulator_enable(core);
-+		if (ret) {
-+			pr_err("failed to enable regulator: %d\n", ret);
-+			goto out_free_table;
-+		}
-+		max_cpu_freq = max(max_cpu_freq, freq);
-+	}
-+
-+	for (i = 0; i < nr_krait_l2_points; i++) {
-+		if (max_cpu_freq >= krait_l2_points[i].cpu_freq) {
-+			if (krait_l2_reg) {
-+				ret = regulator_set_voltage_tol(krait_l2_reg,
-+						krait_l2_points[i].cache_volt,
-+						tol);
-+				if (ret)
-+					pr_err("failed to scale l2 voltage: %d\n",
-+							ret);
-+				ret = regulator_enable(krait_l2_reg);
-+				if (ret)
-+					pr_err("failed to enable l2 voltage: %d\n",
-+							ret);
-+			}
-+			break;
-+		}
-+
-+	}
-+
-+	ret = cpufreq_register_driver(&krait_cpufreq_driver);
-+	if (ret) {
-+		pr_err("failed register driver: %d\n", ret);
-+		goto out_free_table;
-+	}
-+	of_node_put(np);
-+
-+	/*
-+	 * For now, just loading the cooling device;
-+	 * thermal DT code takes care of matching them.
-+	 */
-+	for_each_possible_cpu(cpu) {
-+		dev = get_cpu_device(cpu);
-+		np = of_node_get(dev->of_node);
-+		if (of_find_property(np, "#cooling-cells", NULL)) {
-+			cdev = of_cpufreq_cooling_register(np, cpumask_of(cpu));
-+			if (IS_ERR(cdev))
-+				pr_err("running cpufreq without cooling device: %ld\n",
-+				       PTR_ERR(cdev));
-+		}
-+		of_node_put(np);
-+	}
-+
-+	return 0;
-+
-+out_free_table:
-+	regulator_put(krait_l2_reg);
-+	clk_put(krait_l2_clk);
-+	dev_pm_opp_free_cpufreq_table(cpu_dev, &freq_table);
-+out_put_node:
-+	of_node_put(np);
-+	return ret;
-+}
-+
-+static int krait_cpufreq_remove(struct platform_device *pdev)
-+{
-+	cpufreq_cooling_unregister(cdev);
-+	cpufreq_unregister_driver(&krait_cpufreq_driver);
-+	dev_pm_opp_free_cpufreq_table(cpu_dev, &freq_table);
-+	clk_put(krait_l2_clk);
-+	regulator_put(krait_l2_reg);
-+
-+	return 0;
-+}
-+
-+static struct platform_driver krait_cpufreq_platdrv = {
-+	.driver = {
-+		.name	= "cpufreq-krait",
-+		.owner	= THIS_MODULE,
-+	},
-+	.probe		= krait_cpufreq_probe,
-+	.remove		= krait_cpufreq_remove,
-+};
-+module_platform_driver(krait_cpufreq_platdrv);
-+
-+MODULE_DESCRIPTION("Krait CPUfreq driver");
-+MODULE_LICENSE("GPL v2");
---- a/drivers/cpufreq/qcom-cpufreq.c
-+++ b/drivers/cpufreq/qcom-cpufreq.c
-@@ -168,11 +168,8 @@ static int __init qcom_cpufreq_populate_
- 
- static int __init qcom_cpufreq_driver_init(void)
- {
--	struct cpufreq_dt_platform_data pdata = { .independent_clocks = true };
- 	struct platform_device_info devinfo = {
--		.name = "cpufreq-dt",
--		.data = &pdata,
--		.size_data = sizeof(pdata),
-+		.name = "cpufreq-krait",
- 	};
- 	struct device *cpu_dev;
- 	struct device_node *np;
diff --git a/target/linux/ipq806x/patches-4.4/172-cpufreq-dt-Handle-OPP-voltage-adjust-events.patch b/target/linux/ipq806x/patches-4.4/172-cpufreq-dt-Handle-OPP-voltage-adjust-events.patch
new file mode 100644
index 0000000..60ebe13
--- /dev/null
+++ b/target/linux/ipq806x/patches-4.4/172-cpufreq-dt-Handle-OPP-voltage-adjust-events.patch
@@ -0,0 +1,184 @@
+From 175329015c8a0b480240da222822d2f8316f074d Mon Sep 17 00:00:00 2001
+From: Stephen Boyd <sboyd@codeaurora.org>
+Date: Mon, 1 Jun 2015 18:47:58 -0700
+Subject: cpufreq-dt: Handle OPP voltage adjust events
+
+On some SoCs the Adaptive Voltage Scaling (AVS) technique is
+employed to optimize the operating voltage of a device. At a
+given frequency, the hardware monitors dynamic factors and either
+makes a suggestion for how much to adjust a voltage for the
+current frequency, or it automatically adjusts the voltage
+without software intervention.
+
+In the former case, an AVS driver will call
+dev_pm_opp_modify_voltage() and update the voltage for the
+particular OPP the CPUs are using. Add an OPP notifier to
+cpufreq-dt so that we can adjust the voltage of the CPU when AVS
+updates the OPP.
+
+Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
+---
+ drivers/cpufreq/cpufreq-dt.c | 72 ++++++++++++++++++++++++++++++++++++++++----
+ 1 file changed, 66 insertions(+), 6 deletions(-)
+
+--- a/drivers/cpufreq/cpufreq-dt.c
++++ b/drivers/cpufreq/cpufreq-dt.c
+@@ -34,6 +34,9 @@ struct private_data {
+ 	struct regulator *cpu_reg;
+ 	struct thermal_cooling_device *cdev;
+ 	unsigned int voltage_tolerance; /* in percentage */
++	struct notifier_block opp_nb;
++	struct mutex lock;
++	unsigned long opp_freq;
+ };
+ 
+ static struct freq_attr *cpufreq_dt_attr[] = {
+@@ -42,6 +45,42 @@ static struct freq_attr *cpufreq_dt_attr
+ 	NULL,
+ };
+ 
++static int opp_notifier(struct notifier_block *nb, unsigned long event,
++			void *data)
++{
++	struct dev_pm_opp *opp = data;
++	struct private_data *priv = container_of(nb, struct private_data,
++						 opp_nb);
++	struct device *cpu_dev = priv->cpu_dev;
++	struct regulator *cpu_reg = priv->cpu_reg;
++	unsigned long volt, tol, freq;
++	int ret = 0;
++
++	switch (event) {
++		case OPP_EVENT_ADJUST_VOLTAGE:
++			volt = dev_pm_opp_get_voltage(opp);
++			freq = dev_pm_opp_get_freq(opp);
++			tol = volt * priv->voltage_tolerance / 100;
++
++			mutex_lock(&priv->lock);
++			if (freq == priv->opp_freq)
++				ret = regulator_set_voltage_tol(cpu_reg, volt,
++								tol);
++			mutex_unlock(&priv->lock);
++			if (ret) {
++				dev_err(cpu_dev,
++					"failed to scale voltage up: %d\n",
++					ret);
++				return ret;
++			}
++			break;
++		default:
++			break;
++	}
++
++	return 0;
++}
++
+ static int set_target(struct cpufreq_policy *policy, unsigned int index)
+ {
+ 	struct dev_pm_opp *opp;
+@@ -53,6 +92,7 @@ static int set_target(struct cpufreq_pol
+ 	unsigned long volt = 0, volt_old = 0, tol = 0;
+ 	unsigned int old_freq, new_freq;
+ 	long freq_Hz, freq_exact;
++	unsigned long opp_freq = 0;
+ 	int ret;
+ 
+ 	freq_Hz = clk_round_rate(cpu_clk, freq_table[index].frequency * 1000);
+@@ -63,8 +103,8 @@ static int set_target(struct cpufreq_pol
+ 	new_freq = freq_Hz / 1000;
+ 	old_freq = clk_get_rate(cpu_clk) / 1000;
+ 
++	mutex_lock(&priv->lock);
+ 	if (!IS_ERR(cpu_reg)) {
+-		unsigned long opp_freq;
+ 
+ 		rcu_read_lock();
+ 		opp = dev_pm_opp_find_freq_ceil(cpu_dev, &freq_Hz);
+@@ -72,7 +112,8 @@ static int set_target(struct cpufreq_pol
+ 			rcu_read_unlock();
+ 			dev_err(cpu_dev, "failed to find OPP for %ld\n",
+ 				freq_Hz);
+-			return PTR_ERR(opp);
++			ret = PTR_ERR(opp);
++			goto out;
+ 		}
+ 		volt = dev_pm_opp_get_voltage(opp);
+ 		opp_freq = dev_pm_opp_get_freq(opp);
+@@ -93,7 +134,7 @@ static int set_target(struct cpufreq_pol
+ 		if (ret) {
+ 			dev_err(cpu_dev, "failed to scale voltage up: %d\n",
+ 				ret);
+-			return ret;
++			goto out;
+ 		}
+ 	}
+ 
+@@ -102,7 +143,7 @@ static int set_target(struct cpufreq_pol
+ 		dev_err(cpu_dev, "failed to set clock rate: %d\n", ret);
+ 		if (!IS_ERR(cpu_reg) && volt_old > 0)
+ 			regulator_set_voltage_tol(cpu_reg, volt_old, tol);
+-		return ret;
++		goto out;
+ 	}
+ 
+ 	/* scaling down?  scale voltage after frequency */
+@@ -112,9 +153,12 @@ static int set_target(struct cpufreq_pol
+ 			dev_err(cpu_dev, "failed to scale voltage down: %d\n",
+ 				ret);
+ 			clk_set_rate(cpu_clk, old_freq * 1000);
++			goto out;
+ 		}
+ 	}
+-
++	priv->opp_freq = opp_freq;
++out:
++	mutex_unlock(&priv->lock);
+ 	return ret;
+ }
+ 
+@@ -201,6 +245,7 @@ static int cpufreq_init(struct cpufreq_p
+ 	unsigned int transition_latency;
+ 	bool need_update = false;
+ 	int ret;
++	struct srcu_notifier_head *opp_srcu_head;
+ 
+ 	ret = allocate_resources(policy->cpu, &cpu_dev, &cpu_reg, &cpu_clk);
+ 	if (ret) {
+@@ -277,6 +322,19 @@ static int cpufreq_init(struct cpufreq_p
+ 		goto out_free_opp;
+ 	}
+ 
++	mutex_init(&priv->lock);
++
++	opp_srcu_head = dev_pm_opp_get_notifier(cpu_dev);
++	if (IS_ERR(opp_srcu_head)) {
++		ret = PTR_ERR(opp_srcu_head);
++		goto out_free_priv;
++	}
++
++	priv->opp_nb.notifier_call = opp_notifier;
++	ret = srcu_notifier_chain_register(opp_srcu_head, &priv->opp_nb);
++	if (ret)
++		goto out_free_priv;
++
+ 	of_property_read_u32(np, "voltage-tolerance", &priv->voltage_tolerance);
+ 
+ 	if (!transition_latency)
+@@ -326,7 +384,7 @@ static int cpufreq_init(struct cpufreq_p
+ 	ret = dev_pm_opp_init_cpufreq_table(cpu_dev, &freq_table);
+ 	if (ret) {
+ 		pr_err("failed to init cpufreq table: %d\n", ret);
+-		goto out_free_priv;
++		goto out_unregister_nb;
+ 	}
+ 
+ 	priv->cpu_dev = cpu_dev;
+@@ -365,6 +423,8 @@ static int cpufreq_init(struct cpufreq_p
+ 
+ out_free_cpufreq_table:
+ 	dev_pm_opp_free_cpufreq_table(cpu_dev, &freq_table);
++out_unregister_nb:
++	srcu_notifier_chain_unregister(opp_srcu_head, &priv->opp_nb);
+ out_free_priv:
+ 	kfree(priv);
+ out_free_opp:
diff --git a/target/linux/ipq806x/patches-4.4/173-cpufreq-dt-Add-L2-frequency-scaling-support.patch b/target/linux/ipq806x/patches-4.4/173-cpufreq-dt-Add-L2-frequency-scaling-support.patch
new file mode 100644
index 0000000..5693052
--- /dev/null
+++ b/target/linux/ipq806x/patches-4.4/173-cpufreq-dt-Add-L2-frequency-scaling-support.patch
@@ -0,0 +1,161 @@
+From b4629f9e30e865402c643de6d4668be790fc0539 Mon Sep 17 00:00:00 2001
+From: Georgi Djakov <georgi.djakov@linaro.org>
+Date: Tue, 8 Sep 2015 11:24:41 +0300
+Subject: cpufreq-dt: Add L2 frequency scaling support
+
+Signed-off-by: Georgi Djakov <georgi.djakov@linaro.org>
+
+Conflicts:
+	drivers/cpufreq/cpufreq-dt.c
+---
+ drivers/cpufreq/cpufreq-dt.c | 54 ++++++++++++++++++++++++++++++++++++++------
+ include/linux/cpufreq.h      |  2 ++
+ 2 files changed, 49 insertions(+), 7 deletions(-)
+
+--- a/drivers/cpufreq/cpufreq-dt.c
++++ b/drivers/cpufreq/cpufreq-dt.c
+@@ -86,11 +86,13 @@ static int set_target(struct cpufreq_pol
+ 	struct dev_pm_opp *opp;
+ 	struct cpufreq_frequency_table *freq_table = policy->freq_table;
+ 	struct clk *cpu_clk = policy->clk;
++	struct clk *l2_clk = policy->l2_clk;
+ 	struct private_data *priv = policy->driver_data;
+ 	struct device *cpu_dev = priv->cpu_dev;
+ 	struct regulator *cpu_reg = priv->cpu_reg;
+ 	unsigned long volt = 0, volt_old = 0, tol = 0;
+-	unsigned int old_freq, new_freq;
++	unsigned int old_freq, new_freq, l2_freq;
++	unsigned long new_l2_freq = 0;
+ 	long freq_Hz, freq_exact;
+ 	unsigned long opp_freq = 0;
+ 	int ret;
+@@ -146,6 +148,30 @@ static int set_target(struct cpufreq_pol
+ 		goto out;
+ 	}
+ 
++	if (!IS_ERR(l2_clk) && policy->l2_rate[0] && policy->l2_rate[1] &&
++	    policy->l2_rate[2]) {
++		static unsigned long krait_l2[CONFIG_NR_CPUS] = { };
++		int cpu, ret = 0;
++
++		if (freq_exact >= policy->l2_rate[2])
++			new_l2_freq = policy->l2_rate[2];
++		else if (freq_exact >= policy->l2_rate[1])
++			new_l2_freq = policy->l2_rate[1];
++		else
++			new_l2_freq = policy->l2_rate[0];
++
++		krait_l2[policy->cpu] = new_l2_freq;
++		for_each_present_cpu(cpu)
++			new_l2_freq = max(new_l2_freq, krait_l2[cpu]);
++
++		l2_freq = clk_get_rate(l2_clk);
++
++		if (l2_freq != new_l2_freq) {
++			/* scale l2 with the core */
++			ret = clk_set_rate(l2_clk, new_l2_freq);
++		}
++	}
++
+ 	/* scaling down?  scale voltage after frequency */
+ 	if (!IS_ERR(cpu_reg) && new_freq < old_freq) {
+ 		ret = regulator_set_voltage_tol(cpu_reg, volt, tol);
+@@ -156,18 +182,21 @@ static int set_target(struct cpufreq_pol
+ 			goto out;
+ 		}
+ 	}
++
+ 	priv->opp_freq = opp_freq;
++
+ out:
+ 	mutex_unlock(&priv->lock);
+ 	return ret;
+ }
+ 
+ static int allocate_resources(int cpu, struct device **cdev,
+-			      struct regulator **creg, struct clk **cclk)
++			      struct regulator **creg, struct clk **cclk,
++			      struct clk **l2)
+ {
+ 	struct device *cpu_dev;
+ 	struct regulator *cpu_reg;
+-	struct clk *cpu_clk;
++	struct clk *cpu_clk, *l2_clk = NULL;
+ 	int ret = 0;
+ 	char *reg_cpu0 = "cpu0", *reg_cpu = "cpu", *reg;
+ 
+@@ -227,6 +256,10 @@ try_again:
+ 		*cdev = cpu_dev;
+ 		*creg = cpu_reg;
+ 		*cclk = cpu_clk;
++
++		l2_clk = clk_get(cpu_dev, "l2");
++		if (!IS_ERR(l2_clk))
++			*l2 = l2_clk;
+ 	}
+ 
+ 	return ret;
+@@ -236,18 +269,20 @@ static int cpufreq_init(struct cpufreq_p
+ {
+ 	struct cpufreq_frequency_table *freq_table;
+ 	struct device_node *np;
++	struct device_node *l2_np;
+ 	struct private_data *priv;
+ 	struct device *cpu_dev;
+ 	struct regulator *cpu_reg;
+-	struct clk *cpu_clk;
+ 	struct dev_pm_opp *suspend_opp;
++	struct clk *cpu_clk, *l2_clk;
+ 	unsigned long min_uV = ~0, max_uV = 0;
+ 	unsigned int transition_latency;
+ 	bool need_update = false;
+ 	int ret;
+ 	struct srcu_notifier_head *opp_srcu_head;
+ 
+-	ret = allocate_resources(policy->cpu, &cpu_dev, &cpu_reg, &cpu_clk);
++	ret = allocate_resources(policy->cpu, &cpu_dev, &cpu_reg, &cpu_clk,
++				 &l2_clk);
+ 	if (ret) {
+ 		pr_err("%s: Failed to allocate resources: %d\n", __func__, ret);
+ 		return ret;
+@@ -398,6 +433,11 @@ static int cpufreq_init(struct cpufreq_p
+ 	if (suspend_opp)
+ 		policy->suspend_freq = dev_pm_opp_get_freq(suspend_opp) / 1000;
+ 	rcu_read_unlock();
++	policy->l2_clk = l2_clk;
++
++	l2_np = of_find_node_by_name(NULL, "qcom,l2");
++	if (l2_np)
++		of_property_read_u32_array(l2_np, "qcom,l2-rates", policy->l2_rate, 3);
+ 
+ 	ret = cpufreq_table_validate_and_show(policy, freq_table);
+ 	if (ret) {
+@@ -498,7 +538,7 @@ static int dt_cpufreq_probe(struct platf
+ {
+ 	struct device *cpu_dev;
+ 	struct regulator *cpu_reg;
+-	struct clk *cpu_clk;
++	struct clk *cpu_clk, *l2_clk;
+ 	int ret;
+ 
+ 	/*
+@@ -508,7 +548,7 @@ static int dt_cpufreq_probe(struct platf
+ 	 *
+ 	 * FIXME: Is checking this only for CPU0 sufficient ?
+ 	 */
+-	ret = allocate_resources(0, &cpu_dev, &cpu_reg, &cpu_clk);
++	ret = allocate_resources(0, &cpu_dev, &cpu_reg, &cpu_clk, &l2_clk);
+ 	if (ret)
+ 		return ret;
+ 
+--- a/include/linux/cpufreq.h
++++ b/include/linux/cpufreq.h
+@@ -67,6 +67,8 @@ struct cpufreq_policy {
+ 	unsigned int		cpu;    /* cpu managing this policy, must be online */
+ 
+ 	struct clk		*clk;
++	struct clk		*l2_clk; /* L2 clock */
++	unsigned int		l2_rate[3]; /* L2 bus clock rate thresholds */
+ 	struct cpufreq_cpuinfo	cpuinfo;/* see above */
+ 
+ 	unsigned int		min;    /* in kHz */
diff --git a/target/linux/ipq806x/patches-4.4/174-cpufreq-dt-Add-missing-rcu_read_lock-for-find_device_opp.patch b/target/linux/ipq806x/patches-4.4/174-cpufreq-dt-Add-missing-rcu_read_lock-for-find_device_opp.patch
new file mode 100644
index 0000000..1242721
--- /dev/null
+++ b/target/linux/ipq806x/patches-4.4/174-cpufreq-dt-Add-missing-rcu_read_lock-for-find_device_opp.patch
@@ -0,0 +1,33 @@
+From dafae9c5b39e2871bfd8db0b4bad6e850e42ef49 Mon Sep 17 00:00:00 2001
+From: Georgi Djakov <georgi.djakov@linaro.org>
+Date: Wed, 13 Jan 2016 15:10:25 +0200
+Subject: cpufreq-dt: Add missing rcu_read_lock() for find_device_opp()
+
+The function dev_pm_opp_get_notifier() must be called with held
+rcu_read_lock. In order to keep the pointer valid, add rcu_read_lock().
+
+Signed-off-by: Georgi Djakov <georgi.djakov@linaro.org>
+---
+ drivers/cpufreq/cpufreq-dt.c | 3 +++
+ 1 file changed, 3 insertions(+)
+
+--- a/drivers/cpufreq/cpufreq-dt.c
++++ b/drivers/cpufreq/cpufreq-dt.c
+@@ -359,14 +359,17 @@ static int cpufreq_init(struct cpufreq_p
+ 
+ 	mutex_init(&priv->lock);
+ 
++	rcu_read_lock();
+ 	opp_srcu_head = dev_pm_opp_get_notifier(cpu_dev);
+ 	if (IS_ERR(opp_srcu_head)) {
+ 		ret = PTR_ERR(opp_srcu_head);
++		rcu_read_unlock();
+ 		goto out_free_priv;
+ 	}
+ 
+ 	priv->opp_nb.notifier_call = opp_notifier;
+ 	ret = srcu_notifier_chain_register(opp_srcu_head, &priv->opp_nb);
++	rcu_read_unlock();
+ 	if (ret)
+ 		goto out_free_priv;
+