[PATCH v3 6/7] PM / devfreq: rockchip: add devfreq driver for rk3399 dmc

[Lin Huang]

base on dfi result, we do ddr frequency scaling, register
dmc driver to devfreq framework, and use simple-ondemand
policy.

Signed-off-by: Lin Huang <hl@xxxxxxxxxxxxxx>
---
Changes in v3:
- operate dram setting through sip call
- imporve set rate flow

Changes in v2:
- None
 
Changes in v1:
- move dfi controller to event
- fix set voltage sequence when set rate fail
- change Kconfig type from tristate to bool
- move unuse EXPORT_SYMBOL_GPL()

 drivers/devfreq/Kconfig                 |   1 +
 drivers/devfreq/Makefile                |   1 +
 drivers/devfreq/rockchip/Kconfig        |  15 +
 drivers/devfreq/rockchip/Makefile       |   2 +
 drivers/devfreq/rockchip/rk3399_dmc.c   | 482 ++++++++++++++++++++++++++++++++
 drivers/devfreq/rockchip/rockchip_dmc.c | 143 ++++++++++
 include/soc/rockchip/rockchip_dmc.h     |  45 +++
 7 files changed, 689 insertions(+)
 create mode 100644 drivers/devfreq/rockchip/Kconfig
 create mode 100644 drivers/devfreq/rockchip/Makefile
 create mode 100644 drivers/devfreq/rockchip/rk3399_dmc.c
 create mode 100644 drivers/devfreq/rockchip/rockchip_dmc.c
 create mode 100644 include/soc/rockchip/rockchip_dmc.h

diff --git a/drivers/devfreq/Kconfig b/drivers/devfreq/Kconfig
index a5be56e..cb67246 100644
--- a/drivers/devfreq/Kconfig
+++ b/drivers/devfreq/Kconfig
@@ -101,5 +101,6 @@ config ARM_TEGRA_DEVFREQ
          operating frequencies and voltages with OPP support.
 
 source "drivers/devfreq/event/Kconfig"
+source "drivers/devfreq/rockchip/Kconfig"
 
 endif # PM_DEVFREQ
diff --git a/drivers/devfreq/Makefile b/drivers/devfreq/Makefile
index 09f11d9..48e2ae6 100644
--- a/drivers/devfreq/Makefile
+++ b/drivers/devfreq/Makefile
@@ -9,6 +9,7 @@ obj-$(CONFIG_DEVFREQ_GOV_PASSIVE)	+= governor_passive.o
 # DEVFREQ Drivers
 obj-$(CONFIG_ARM_EXYNOS_BUS_DEVFREQ)	+= exynos-bus.o
 obj-$(CONFIG_ARM_TEGRA_DEVFREQ)		+= tegra-devfreq.o
+obj-$(CONFIG_ARCH_ROCKCHIP)		+= rockchip/
 
 # DEVFREQ Event Drivers
 obj-$(CONFIG_PM_DEVFREQ_EVENT)		+= event/
diff --git a/drivers/devfreq/rockchip/Kconfig b/drivers/devfreq/rockchip/Kconfig
new file mode 100644
index 0000000..7fb1cff
--- /dev/null
+++ b/drivers/devfreq/rockchip/Kconfig
@@ -0,0 +1,15 @@
+config ARM_ROCKCHIP_DMC_DEVFREQ
+	bool "ARM ROCKCHIP DMC DEVFREQ Driver"
+	depends on ARCH_ROCKCHIP
+	help
+	  This adds the DEVFREQ driver framework for the rockchip dmc.
+
+config ARM_RK3399_DMC_DEVFREQ
+	bool "ARM RK3399 DMC DEVFREQ Driver"
+	depends on ARM_ROCKCHIP_DMC_DEVFREQ
+	select PM_OPP
+	select DEVFREQ_GOV_SIMPLE_ONDEMAND
+	help
+          This adds the DEVFREQ driver for the RK3399 dmc. It sets the frequency
+          for the memory controller and reads the usage counts from hardware.
+
diff --git a/drivers/devfreq/rockchip/Makefile b/drivers/devfreq/rockchip/Makefile
new file mode 100644
index 0000000..caca525
--- /dev/null
+++ b/drivers/devfreq/rockchip/Makefile
@@ -0,0 +1,2 @@
+obj-$(CONFIG_ARM_ROCKCHIP_DMC_DEVFREQ)	+= rockchip_dmc.o
+obj-$(CONFIG_ARM_RK3399_DMC_DEVFREQ)	+= rk3399_dmc.o
diff --git a/drivers/devfreq/rockchip/rk3399_dmc.c b/drivers/devfreq/rockchip/rk3399_dmc.c
new file mode 100644
index 0000000..f1d6120
--- /dev/null
+++ b/drivers/devfreq/rockchip/rk3399_dmc.c
@@ -0,0 +1,482 @@
+/*
+ * Copyright (c) 2016, Fuzhou Rockchip Electronics Co., Ltd
+ * Author: Lin Huang <hl@xxxxxxxxxxxxxx>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+ * more details.
+ */
+
+#include <linux/clk.h>
+#include <linux/completion.h>
+#include <linux/delay.h>
+#include <linux/devfreq.h>
+#include <linux/devfreq-event.h>
+#include <linux/interrupt.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/pm_opp.h>
+#include <linux/regulator/consumer.h>
+#include <linux/rwsem.h>
+#include <linux/suspend.h>
+#include <linux/syscore_ops.h>
+
+#include <soc/rockchip/rockchip_dmc.h>
+#include "../../firmware/rockchip_sip.h"
+
+struct dram_timing {
+	unsigned int ddr3_speed_bin;
+	unsigned int pd_idle;
+	unsigned int sr_idle;
+	unsigned int sr_mc_gate_idle;
+	unsigned int srpd_lite_idle;
+	unsigned int standby_idle;
+	unsigned int dram_dll_dis_freq;
+	unsigned int phy_dll_dis_freq;
+	unsigned int ddr3_odt_dis_freq;
+	unsigned int ddr3_drv;
+	unsigned int ddr3_odt;
+	unsigned int phy_ddr3_ca_drv;
+	unsigned int phy_ddr3_dq_drv;
+	unsigned int phy_ddr3_odt;
+	unsigned int lpddr3_odt_dis_freq;
+	unsigned int lpddr3_drv;
+	unsigned int lpddr3_odt;
+	unsigned int phy_lpddr3_ca_drv;
+	unsigned int phy_lpddr3_dq_drv;
+	unsigned int phy_lpddr3_odt;
+	unsigned int lpddr4_odt_dis_freq;
+	unsigned int lpddr4_drv;
+	unsigned int lpddr4_dq_odt;
+	unsigned int lpddr4_ca_odt;
+	unsigned int phy_lpddr4_ca_drv;
+	unsigned int phy_lpddr4_ck_cs_drv;
+	unsigned int phy_lpddr4_dq_drv;
+	unsigned int phy_lpddr4_odt;
+};
+
+struct rk3399_dmcfreq {
+	struct device *dev;
+	struct devfreq *devfreq;
+	struct devfreq_simple_ondemand_data ondemand_data;
+	struct clk *dmc_clk;
+	struct devfreq_event_dev *edev;
+	struct mutex lock;
+	struct notifier_block dmc_nb;
+	struct dram_timing *timing;
+	wait_queue_head_t	wait_dcf_queue;
+	int irq;
+	int wait_dcf_flag;
+	struct regulator *vdd_center;
+	unsigned long rate, target_rate;
+	unsigned long volt, target_volt;
+};
+
+static int rk3399_dmcfreq_target(struct device *dev, unsigned long *freq,
+				 u32 flags)
+{
+	struct platform_device *pdev = container_of(dev, struct platform_device,
+						    dev);
+	struct rk3399_dmcfreq *dmcfreq = platform_get_drvdata(pdev);
+	struct dev_pm_opp *opp;
+	unsigned long old_clk_rate = dmcfreq->rate;
+	unsigned long target_volt, target_rate;
+	int err;
+
+	rcu_read_lock();
+	opp = devfreq_recommended_opp(dev, freq, flags);
+	if (IS_ERR(opp)) {
+		rcu_read_unlock();
+		return PTR_ERR(opp);
+	}
+	target_rate = dev_pm_opp_get_freq(opp);
+	target_volt = dev_pm_opp_get_voltage(opp);
+	opp = devfreq_recommended_opp(dev, &dmcfreq->rate, flags);
+	if (IS_ERR(opp)) {
+		rcu_read_unlock();
+		return PTR_ERR(opp);
+	}
+	dmcfreq->volt = dev_pm_opp_get_voltage(opp);
+	rcu_read_unlock();
+
+	if (dmcfreq->rate == target_rate)
+		return 0;
+
+	mutex_lock(&dmcfreq->lock);
+	/*
+	 * if frequency scaling from low to high, adjust voltage first;
+	 * if frequency scaling from high to low, adjuset frequency first;
+	 */
+	if (old_clk_rate < target_rate) {
+		err = regulator_set_voltage(dmcfreq->vdd_center, target_volt,
+					    target_volt);
+		if (err) {
+			dev_err(dev, "Unable to set vol %lu\n", target_volt);
+			goto out;
+		}
+	}
+
+	dmc_event(DMCFREQ_ADJUST);
+	dmcfreq->wait_dcf_flag = 1;
+
+	err = clk_set_rate(dmcfreq->dmc_clk, target_rate);
+	if (err) {
+		dev_err(dev,
+			"Unable to set freq %lu. Current freq %lu. Error %d\n",
+			target_rate, old_clk_rate, err);
+		regulator_set_voltage(dmcfreq->vdd_center, dmcfreq->volt,
+				      dmcfreq->volt);
+		dmc_event(DMCFREQ_FINISH);
+		goto out;
+	}
+
+	/*
+	 * wait until bcf irq happen, it means freq scaling finish in bl31,
+	 * use 100ms as timeout time
+	 */
+	wait_event_timeout(dmcfreq->wait_dcf_queue,
+			   !dmcfreq->wait_dcf_flag, HZ / 10);
+
+	dmc_event(DMCFREQ_FINISH);
+
+	/*
+	 * check the dpll rate
+	 * there only two result we will get,
+	 * 1. ddr frequency scaling fail, we still get the old rate
+	 * 2, ddr frequency scaling sucessful, we get the rate we set
+	 */
+	dmcfreq->rate = clk_get_rate(dmcfreq->dmc_clk);
+
+	/* if get the incorrect rate, set voltage to old value */
+	if (dmcfreq->rate != target_rate) {
+		dev_err(dev, "get wrong ddr frequency, Request freq %lu,\
+			Current freq %lu\n", target_rate, dmcfreq->rate);
+		regulator_set_voltage(dmcfreq->vdd_center, dmcfreq->volt,
+				      dmcfreq->volt);
+	} else if (old_clk_rate > target_rate)
+		err = regulator_set_voltage(dmcfreq->vdd_center, target_volt,
+					    target_volt);
+	if (err)
+		dev_err(dev, "Unable to set vol %lu\n", target_volt);
+
+out:
+	mutex_unlock(&dmcfreq->lock);
+	return err;
+}
+
+static int rk3399_dmcfreq_get_dev_status(struct device *dev,
+					 struct devfreq_dev_status *stat)
+{
+	struct platform_device *pdev = container_of(dev, struct platform_device,
+						    dev);
+	struct rk3399_dmcfreq *dmcfreq = platform_get_drvdata(pdev);
+	struct devfreq_event_data edata;
+
+	devfreq_event_get_event(dmcfreq->edev, &edata);
+
+	stat->current_frequency = dmcfreq->rate;
+	stat->busy_time = edata.load_count;
+	stat->total_time = edata.total_count;
+
+	return 0;
+}
+
+static int rk3399_dmcfreq_get_cur_freq(struct device *dev, unsigned long *freq)
+{
+	struct platform_device *pdev = container_of(dev, struct platform_device,
+						    dev);
+	struct rk3399_dmcfreq *dmcfreq = platform_get_drvdata(pdev);
+
+	*freq = dmcfreq->rate;
+
+	return 0;
+}
+
+static void rk3399_dmcfreq_exit(struct device *dev)
+{
+	struct platform_device *pdev = container_of(dev, struct platform_device,
+						    dev);
+	struct rk3399_dmcfreq *dmcfreq = platform_get_drvdata(pdev);
+
+	devfreq_unregister_opp_notifier(dev, dmcfreq->devfreq);
+}
+
+static struct devfreq_dev_profile rk3399_devfreq_dmc_profile = {
+	.polling_ms	= 200,
+	.target		= rk3399_dmcfreq_target,
+	.get_dev_status	= rk3399_dmcfreq_get_dev_status,
+	.get_cur_freq	= rk3399_dmcfreq_get_cur_freq,
+	.exit		= rk3399_dmcfreq_exit,
+};
+
+static __maybe_unused int rk3399_dmcfreq_suspend(struct device *dev)
+{
+	rockchip_dmc_disable();
+	return 0;
+}
+
+static __maybe_unused int rk3399_dmcfreq_resume(struct device *dev)
+{
+	rockchip_dmc_enable();
+	return 0;
+}
+
+static SIMPLE_DEV_PM_OPS(rk3399_dmcfreq_pm, rk3399_dmcfreq_suspend,
+			 rk3399_dmcfreq_resume);
+
+static int rk3399_dmc_enable_notify(struct notifier_block *nb,
+				    unsigned long event, void *data)
+{
+	struct rk3399_dmcfreq *dmcfreq =
+			      container_of(nb, struct rk3399_dmcfreq, dmc_nb);
+	unsigned long freq = ULONG_MAX;
+
+	if (event == DMC_ENABLE) {
+		devfreq_event_enable_edev(dmcfreq->edev);
+		devfreq_resume_device(dmcfreq->devfreq);
+		return NOTIFY_OK;
+	} else if (event == DMC_DISABLE) {
+		devfreq_event_disable_edev(dmcfreq->edev);
+		devfreq_suspend_device(dmcfreq->devfreq);
+
+		/* when disable dmc, set sdram to max frequency */
+		rk3399_dmcfreq_target(dmcfreq->dev, &freq, 0);
+		return NOTIFY_OK;
+	}
+
+	return NOTIFY_DONE;
+}
+
+static irqreturn_t rk3399_dmc_irq(int irq, void *dev_id)
+{
+	struct rk3399_dmcfreq *dmcfreq = dev_id;
+
+	dmcfreq->wait_dcf_flag = 0;
+	wake_up(&dmcfreq->wait_dcf_queue);
+
+	/* clr dcf irq */
+	sip_smc_clr_ddr_irq();
+
+	return IRQ_HANDLED;
+}
+
+static int of_do_get_timing(struct device_node *np,
+		struct dram_timing *timing)
+{
+	int ret;
+
+	ret = of_property_read_u32(np, "ddr3_speed_bin",
+				   &timing->ddr3_speed_bin);
+	ret |= of_property_read_u32(np, "pd_idle", &timing->pd_idle);
+	ret |= of_property_read_u32(np, "sr_idle", &timing->sr_idle);
+	ret |= of_property_read_u32(np, "sr_mc_gate_idle",
+				    &timing->sr_mc_gate_idle);
+	ret |= of_property_read_u32(np, "srpd_lite_idle",
+				    &timing->srpd_lite_idle);
+	ret |= of_property_read_u32(np, "standby_idle", &timing->standby_idle);
+	ret |= of_property_read_u32(np, "dram_dll_dis_freq",
+				    &timing->dram_dll_dis_freq);
+	ret |= of_property_read_u32(np, "phy_dll_dis_freq",
+				    &timing->phy_dll_dis_freq);
+	ret |= of_property_read_u32(np, "ddr3_odt_dis_freq",
+				    &timing->ddr3_odt_dis_freq);
+	ret |= of_property_read_u32(np, "ddr3_drv", &timing->ddr3_drv);
+	ret |= of_property_read_u32(np, "ddr3_odt", &timing->ddr3_odt);
+	ret |= of_property_read_u32(np, "phy_ddr3_ca_drv",
+				    &timing->phy_ddr3_ca_drv);
+	ret |= of_property_read_u32(np, "phy_ddr3_dq_drv",
+				    &timing->phy_ddr3_dq_drv);
+	ret |= of_property_read_u32(np, "phy_ddr3_odt", &timing->phy_ddr3_odt);
+	ret |= of_property_read_u32(np, "lpddr3_odt_dis_freq",
+				    &timing->lpddr3_odt_dis_freq);
+	ret |= of_property_read_u32(np, "lpddr3_drv", &timing->lpddr3_drv);
+	ret |= of_property_read_u32(np, "lpddr3_odt", &timing->lpddr3_odt);
+	ret |= of_property_read_u32(np, "phy_lpddr3_ca_drv",
+				    &timing->phy_lpddr3_ca_drv);
+	ret |= of_property_read_u32(np, "phy_lpddr3_dq_drv",
+				    &timing->phy_lpddr3_dq_drv);
+	ret |= of_property_read_u32(np, "phy_lpddr3_odt",
+				    &timing->phy_lpddr3_odt);
+	ret |= of_property_read_u32(np, "lpddr4_odt_dis_freq",
+				    &timing->lpddr4_odt_dis_freq);
+	ret |= of_property_read_u32(np, "lpddr4_drv",
+				    &timing->lpddr4_drv);
+	ret |= of_property_read_u32(np, "lpddr4_dq_odt",
+				    &timing->lpddr4_dq_odt);
+	ret |= of_property_read_u32(np, "lpddr4_ca_odt",
+				    &timing->lpddr4_ca_odt);
+	ret |= of_property_read_u32(np, "phy_lpddr4_ca_drv",
+				    &timing->phy_lpddr4_ca_drv);
+	ret |= of_property_read_u32(np, "phy_lpddr4_ck_cs_drv",
+				    &timing->phy_lpddr4_ck_cs_drv);
+	ret |= of_property_read_u32(np, "phy_lpddr4_dq_drv",
+				    &timing->phy_lpddr4_dq_drv);
+	ret |= of_property_read_u32(np, "phy_lpddr4_odt",
+				    &timing->phy_lpddr4_odt);
+
+	return ret;
+}
+
+static struct dram_timing *of_get_ddr_timings(struct device *dev,
+					      struct device_node *np)
+{
+	struct dram_timing	*timing = NULL;
+	struct device_node	*np_tim;
+
+	np_tim = of_parse_phandle(np, "ddr_timing", 0);
+	if (np_tim) {
+		timing = devm_kzalloc(dev, sizeof(*timing), GFP_KERNEL);
+		if (!timing)
+			goto err;
+		if (of_do_get_timing(np_tim, timing)) {
+			devm_kfree(dev, timing);
+			goto err;
+		}
+		return timing;
+	}
+
+err:
+	if (timing) {
+		devm_kfree(dev, timing);
+		timing = NULL;
+	}
+
+	return timing;
+}
+
+static int rk3399_dmcfreq_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct rk3399_dmcfreq *data;
+	int ret, irq, index;
+	uint64_t param = 0;
+	uint32_t *timing;
+	struct device_node *np = pdev->dev.of_node;
+
+	irq = platform_get_irq(pdev, 0);
+	if (irq < 0) {
+		dev_err(&pdev->dev, "no dmc irq resource\n");
+		return -EINVAL;
+	}
+
+	data = devm_kzalloc(dev, sizeof(struct rk3399_dmcfreq), GFP_KERNEL);
+	if (!data)
+		return -ENOMEM;
+
+	mutex_init(&data->lock);
+
+	data->vdd_center = devm_regulator_get(dev, "center");
+	if (IS_ERR(data->vdd_center)) {
+		dev_err(dev, "Cannot get the regulator \"center\"\n");
+		return PTR_ERR(data->vdd_center);
+	}
+
+	data->dmc_clk = devm_clk_get(dev, "dmc_clk");
+	if (IS_ERR(data->dmc_clk)) {
+		dev_err(dev, "Cannot get the clk dmc_clk\n");
+		return PTR_ERR(data->dmc_clk);
+	};
+
+	data->edev = devfreq_event_get_edev_by_phandle(dev, 0);
+	if (IS_ERR(data->edev))
+		return -EPROBE_DEFER;
+
+	ret = devfreq_event_enable_edev(data->edev);
+	if (ret < 0) {
+		dev_err(dev, "failed to enable devfreq-event devices\n");
+		return ret;
+	}
+
+	/*
+	 * We add a devfreq driver to our parent since it has a device tree node
+	 * with operating points.
+	 */
+	if (dev_pm_opp_of_add_table(dev)) {
+		dev_err(dev, "Invalid operating-points in device tree.\n");
+		return -EINVAL;
+	}
+
+	of_property_read_u32(np, "upthreshold",
+			     &data->ondemand_data.upthreshold);
+
+	of_property_read_u32(np, "downdifferential",
+			     &data->ondemand_data.downdifferential);
+
+	data->rate = clk_get_rate(data->dmc_clk);
+	rk3399_devfreq_dmc_profile.initial_freq = data->rate;
+	data->devfreq = devfreq_add_device(dev,
+					   &rk3399_devfreq_dmc_profile,
+					   "simple_ondemand",
+					   &data->ondemand_data);
+	if (IS_ERR(data->devfreq))
+		return PTR_ERR(data->devfreq);
+
+	devfreq_register_opp_notifier(dev, data->devfreq);
+
+	data->dmc_nb.notifier_call = rk3399_dmc_enable_notify;
+	dmc_register_notifier(&data->dmc_nb);
+	data->irq = irq;
+	ret = devm_request_irq(dev, irq, rk3399_dmc_irq, 0,
+			       dev_name(dev), data);
+	if (ret) {
+		dev_err(dev, "failed to request dmc irq: %d\n", ret);
+		return ret;
+	}
+
+	/* get dram timing and pass it to bl31 */
+	data->timing = of_get_ddr_timings(dev, np);
+	if (data->timing) {
+		timing = (uint32_t *)data->timing;
+		for (index = 0; index < (sizeof(struct dram_timing) / 4);
+		     index++) {
+			param = index;
+			param = param << 32 | *timing++;
+			sip_smc_set_ddr_param(param);
+			param = 0;
+		}
+	}
+	sip_smc_ddr_init();
+
+	init_waitqueue_head(&data->wait_dcf_queue);
+	data->wait_dcf_flag = 0;
+
+	data->dev = dev;
+	platform_set_drvdata(pdev, data);
+
+	return 0;
+}
+
+static int rk3399_dmcfreq_remove(struct platform_device *pdev)
+{
+	struct rk3399_dmcfreq *dmcfreq = platform_get_drvdata(pdev);
+
+	devfreq_remove_device(dmcfreq->devfreq);
+	regulator_put(dmcfreq->vdd_center);
+
+	return 0;
+}
+
+static const struct of_device_id rk3399dmc_devfreq_of_match[] = {
+	{ .compatible = "rockchip,rk3399-dmc" },
+	{ },
+};
+
+static struct platform_driver rk3399_dmcfreq_driver = {
+	.probe	= rk3399_dmcfreq_probe,
+	.remove	= rk3399_dmcfreq_remove,
+	.driver = {
+		.name	= "rk3399-dmc-freq",
+		.pm	= &rk3399_dmcfreq_pm,
+		.of_match_table = rk3399dmc_devfreq_of_match,
+	},
+};
+module_platform_driver(rk3399_dmcfreq_driver);
+
+MODULE_LICENSE("GPL v2");
+MODULE_DESCRIPTION("RK3399 dmcfreq driver with devfreq framework");
diff --git a/drivers/devfreq/rockchip/rockchip_dmc.c b/drivers/devfreq/rockchip/rockchip_dmc.c
new file mode 100644
index 0000000..78baee5
--- /dev/null
+++ b/drivers/devfreq/rockchip/rockchip_dmc.c
@@ -0,0 +1,143 @@
+/*
+ * Copyright (c) 2016, Fuzhou Rockchip Electronics Co., Ltd
+ * Author: Lin Huang <hl@xxxxxxxxxxxxxx>
+ * Base on: https://chromium-review.googlesource.com/#/c/231477/
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+ * more details.
+ */
+
+#include <linux/mutex.h>
+#include <soc/rockchip/rockchip_dmc.h>
+
+static int num_wait;
+static int num_disable;
+static BLOCKING_NOTIFIER_HEAD(dmc_notifier_list);
+static DEFINE_MUTEX(dmc_en_lock);
+static DEFINE_MUTEX(dmc_sync_lock);
+
+/**
+ * rockchip_dmc_enabled - Returns true if dmc freq is enabled, false otherwise.
+ */
+bool rockchip_dmc_enabled(void)
+{
+	return num_disable <= 0 && num_wait <= 1;
+}
+
+/**
+ * rockchip_dmc_enable - Enable dmc frequency scaling. Will only enable
+ * frequency scaling if there are 1 or fewer notifiers. Call to undo
+ * rockchip_dmc_disable.
+ */
+void rockchip_dmc_enable(void)
+{
+	mutex_lock(&dmc_en_lock);
+	num_disable--;
+	WARN_ON(num_disable < 0);
+	if (rockchip_dmc_enabled())
+		dmc_event(DMC_ENABLE);
+	mutex_unlock(&dmc_en_lock);
+}
+
+/**
+ * rockchip_dmc_disable - Disable dmc frequency scaling. Call when something
+ * cannot coincide with dmc frequency scaling.
+ */
+void rockchip_dmc_disable(void)
+{
+	mutex_lock(&dmc_en_lock);
+	if (rockchip_dmc_enabled())
+		dmc_event(DMC_DISABLE);
+	num_disable++;
+	mutex_unlock(&dmc_en_lock);
+}
+
+void dmc_event(int event)
+{
+	mutex_lock(&dmc_sync_lock);
+	blocking_notifier_call_chain(&dmc_notifier_list, event, NULL);
+	mutex_unlock(&dmc_sync_lock);
+}
+
+/**
+ * dmc_register_notifier - register a driver to dmc chain
+ * @nb: notifier function to register
+ */
+int dmc_register_notifier(struct notifier_block *nb)
+{
+	int ret;
+
+	if (!nb)
+		return -EINVAL;
+
+	ret = blocking_notifier_chain_register(&dmc_notifier_list, nb);
+
+	return ret;
+}
+
+/**
+ * dmc_unregister_notifier - unregister a driver from dmc chain
+ * @nb: remove notifier function
+ */
+int dmc_unregister_notifier(struct notifier_block *nb)
+{
+	int ret;
+
+	if (!nb)
+		return -EINVAL;
+
+	ret = blocking_notifier_chain_unregister(&dmc_notifier_list, nb);
+
+	return ret;
+}
+
+/**
+ * rockchip_dmc_get - Register the notifier block for the dmc chain.
+ * @nb The dmc notifier block to register
+ */
+int rockchip_dmc_get(struct notifier_block *nb)
+{
+	if (!nb)
+		return -EINVAL;
+
+	mutex_lock(&dmc_en_lock);
+
+	/*
+	 * if have two notifier(enable two vop etc),
+	 * need to disable dmc
+	 */
+	if (num_wait == 1 && num_disable <= 0)
+		dmc_event(DMC_DISABLE);
+	num_wait++;
+	dmc_register_notifier(nb);
+	mutex_unlock(&dmc_en_lock);
+
+	return 0;
+}
+
+/**
+ * rockchip_dmc_put - Remove the notifier block from the dmc chain.
+ * @nb The dmc notifier block to unregister
+ */
+int rockchip_dmc_put(struct notifier_block *nb)
+{
+	if (!nb)
+		return -EINVAL;
+
+	mutex_lock(&dmc_en_lock);
+	num_wait--;
+
+	/* if notifier from 2 back to 1, enable dmc again */
+	if (num_wait == 1 && num_disable <= 0)
+		dmc_event(DMC_ENABLE);
+	dmc_unregister_notifier(nb);
+	mutex_unlock(&dmc_en_lock);
+
+	return 0;
+}
diff --git a/include/soc/rockchip/rockchip_dmc.h b/include/soc/rockchip/rockchip_dmc.h
new file mode 100644
index 0000000..3f69cbf
--- /dev/null
+++ b/include/soc/rockchip/rockchip_dmc.h
@@ -0,0 +1,45 @@
+/*
+ * Copyright (c) 2016, Fuzhou Rockchip Electronics Co., Ltd
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+ * more details.
+ */
+
+#ifndef __SOC_ROCKCHIP_DMC_H
+#define __SOC_ROCKCHIP_DMC_H
+
+#include <linux/notifier.h>
+
+#define DMC_ENABLE	0
+#define DMC_DISABLE	1
+#define DMCFREQ_ADJUST	2
+#define DMCFREQ_FINISH	3
+
+#if IS_ENABLED(CONFIG_ARM_ROCKCHIP_DMC_DEVFREQ)
+int rockchip_dmc_get(struct notifier_block *nb);
+int rockchip_dmc_put(struct notifier_block *nb);
+#else
+static inline int rockchip_dmc_get(struct notifier_block *nb)
+{
+	return 0;
+}
+
+static inline int rockchip_dmc_put(struct notifier_block *nb)
+{
+	return 0;
+}
+#endif
+
+void dmc_event(int event);
+int dmc_register_notifier(struct notifier_block *nb);
+int dmc_unregister_notifier(struct notifier_block *nb);
+void rockchip_dmc_enable(void);
+void rockchip_dmc_disable(void);
+bool rockchip_dmc_enabled(void);
+#endif
-- 
2.6.6