PM / devfreq: event: support rockchip dfi controller

on rk3399 platform, there is dfi conroller can monitor
ddr load, base on this result, we can do ddr freqency
scaling.

Signed-off-by: Lin Huang <[e-mail]>
Signed-off-by: MyungJoo Ham <[e-mail]>
Acked-by: Chanwoo Choi <[e-mail]>

drivers/devfreq/event/Kconfig

···
 	  (Platform Performance Monitoring Unit) counters to estimate the
 	  utilization of each module.
 
+config DEVFREQ_EVENT_ROCKCHIP_DFI
+	tristate "ROCKCHIP DFI DEVFREQ event Driver"
+	depends on ARCH_ROCKCHIP
+	help
+	  This add the devfreq-event driver for Rockchip SoC. It provides DFI
+	  (DDR Monitor Module) driver to count ddr load.
+
 endif # PM_DEVFREQ_EVENT

drivers/devfreq/event/Makefile

···
 
 obj-$(CONFIG_DEVFREQ_EVENT_EXYNOS_NOCP) += exynos-nocp.o
 obj-$(CONFIG_DEVFREQ_EVENT_EXYNOS_PPMU) += exynos-ppmu.o
+obj-$(CONFIG_DEVFREQ_EVENT_ROCKCHIP_DFI) += rockchip-dfi.o

drivers/devfreq/event/rockchip-dfi.c

···
+/*
+ * Copyright (c) 2016, Fuzhou Rockchip Electronics Co., Ltd
+ * Author: Lin Huang <[e-mail]>
+ *
+ * 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/devfreq-event.h>
+#include <linux/kernel.h>
+#include <linux/err.h>
+#include <linux/init.h>
+#include <linux/io.h>
+#include <linux/mfd/syscon.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/regmap.h>
+#include <linux/slab.h>
+#include <linux/list.h>
+#include <linux/of.h>
+
+#define RK3399_DMC_NUM_CH	2
+
+/* DDRMON_CTRL */
+#define DDRMON_CTRL	0x04
+#define CLR_DDRMON_CTRL	(0x1f0000 << 0)
+#define LPDDR4_EN	(0x10001 << 4)
+#define HARDWARE_EN	(0x10001 << 3)
+#define LPDDR3_EN	(0x10001 << 2)
+#define SOFTWARE_EN	(0x10001 << 1)
+#define SOFTWARE_DIS	(0x10000 << 1)
+#define TIME_CNT_EN	(0x10001 << 0)
+
+#define DDRMON_CH0_COUNT_NUM		0x28
+#define DDRMON_CH0_DFI_ACCESS_NUM	0x2c
+#define DDRMON_CH1_COUNT_NUM		0x3c
+#define DDRMON_CH1_DFI_ACCESS_NUM	0x40
+
+/* pmu grf */
+#define PMUGRF_OS_REG2	0x308
+#define DDRTYPE_SHIFT	13
+#define DDRTYPE_MASK	7
+
+enum {
+	DDR3 = 3,
+	LPDDR3 = 6,
+	LPDDR4 = 7,
+	UNUSED = 0xFF
+};
+
+struct dmc_usage {
+	u32 access;
+	u32 total;
+};
+
+/*
+ * The dfi controller can monitor DDR load. It has an upper and lower threshold
+ * for the operating points. Whenever the usage leaves these bounds an event is
+ * generated to indicate the DDR frequency should be changed.
+ */
+struct rockchip_dfi {
+	struct devfreq_event_dev *edev;
+	struct devfreq_event_desc *desc;
+	struct dmc_usage ch_usage[RK3399_DMC_NUM_CH];
+	struct device *dev;
+	void __iomem *regs;
+	struct regmap *regmap_pmu;
+	struct clk *clk;
+};
+
+static void rockchip_dfi_start_hardware_counter(struct devfreq_event_dev *edev)
+{
+	struct rockchip_dfi *info = devfreq_event_get_drvdata(edev);
+	void __iomem *dfi_regs = info->regs;
+	u32 val;
+	u32 ddr_type;
+
+	/* get ddr type */
+	regmap_read(info->regmap_pmu, PMUGRF_OS_REG2, &val);
+	ddr_type = (val >> DDRTYPE_SHIFT) & DDRTYPE_MASK;
+
+	/* clear DDRMON_CTRL setting */
+	writel_relaxed(CLR_DDRMON_CTRL, dfi_regs + DDRMON_CTRL);
+
+	/* set ddr type to dfi */
+	if (ddr_type == LPDDR3)
+		writel_relaxed(LPDDR3_EN, dfi_regs + DDRMON_CTRL);
+	else if (ddr_type == LPDDR4)
+		writel_relaxed(LPDDR4_EN, dfi_regs + DDRMON_CTRL);
+
+	/* enable count, use software mode */
+	writel_relaxed(SOFTWARE_EN, dfi_regs + DDRMON_CTRL);
+}
+
+static void rockchip_dfi_stop_hardware_counter(struct devfreq_event_dev *edev)
+{
+	struct rockchip_dfi *info = devfreq_event_get_drvdata(edev);
+	void __iomem *dfi_regs = info->regs;
+
+	writel_relaxed(SOFTWARE_DIS, dfi_regs + DDRMON_CTRL);
+}
+
+static int rockchip_dfi_get_busier_ch(struct devfreq_event_dev *edev)
+{
+	struct rockchip_dfi *info = devfreq_event_get_drvdata(edev);
+	u32 tmp, max = 0;
+	u32 i, busier_ch = 0;
+	void __iomem *dfi_regs = info->regs;
+
+	rockchip_dfi_stop_hardware_counter(edev);
+
+	/* Find out which channel is busier */
+	for (i = 0; i < RK3399_DMC_NUM_CH; i++) {
+		info->ch_usage[i].access = readl_relaxed(dfi_regs +
+				DDRMON_CH0_DFI_ACCESS_NUM + i * 20) * 4;
+		info->ch_usage[i].total = readl_relaxed(dfi_regs +
+				DDRMON_CH0_COUNT_NUM + i * 20);
+		tmp = info->ch_usage[i].access;
+		if (tmp > max) {
+			busier_ch = i;
+			max = tmp;
+		}
+	}
+	rockchip_dfi_start_hardware_counter(edev);
+
+	return busier_ch;
+}
+
+static int rockchip_dfi_disable(struct devfreq_event_dev *edev)
+{
+	struct rockchip_dfi *info = devfreq_event_get_drvdata(edev);
+
+	rockchip_dfi_stop_hardware_counter(edev);
+	clk_disable_unprepare(info->clk);
+
+	return 0;
+}
+
+static int rockchip_dfi_enable(struct devfreq_event_dev *edev)
+{
+	struct rockchip_dfi *info = devfreq_event_get_drvdata(edev);
+	int ret;
+
+	ret = clk_prepare_enable(info->clk);
+	if (ret) {
+		dev_err(&edev->dev, "failed to enable dfi clk: %d\n", ret);
+		return ret;
+	}
+
+	rockchip_dfi_start_hardware_counter(edev);
+	return 0;
+}
+
+static int rockchip_dfi_set_event(struct devfreq_event_dev *edev)
+{
+	return 0;
+}
+
+static int rockchip_dfi_get_event(struct devfreq_event_dev *edev,
+				  struct devfreq_event_data *edata)
+{
+	struct rockchip_dfi *info = devfreq_event_get_drvdata(edev);
+	int busier_ch;
+
+	busier_ch = rockchip_dfi_get_busier_ch(edev);
+
+	edata->load_count = info->ch_usage[busier_ch].access;
+	edata->total_count = info->ch_usage[busier_ch].total;
+
+	return 0;
+}
+
+static const struct devfreq_event_ops rockchip_dfi_ops = {
+	.disable = rockchip_dfi_disable,
+	.enable = rockchip_dfi_enable,
+	.get_event = rockchip_dfi_get_event,
+	.set_event = rockchip_dfi_set_event,
+};
+
+static const struct of_device_id rockchip_dfi_id_match[] = {
+	{ .compatible = "rockchip,rk3399-dfi" },
+	{ },
+};
+
+static int rockchip_dfi_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct rockchip_dfi *data;
+	struct resource *res;
+	struct devfreq_event_desc *desc;
+	struct device_node *np = pdev->dev.of_node, *node;
+
+	data = devm_kzalloc(dev, sizeof(struct rockchip_dfi), GFP_KERNEL);
+	if (!data)
+		return -ENOMEM;
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	data->regs = devm_ioremap_resource(&pdev->dev, res);
+	if (IS_ERR(data->regs))
+		return PTR_ERR(data->regs);
+
+	data->clk = devm_clk_get(dev, "pclk_ddr_mon");
+	if (IS_ERR(data->clk)) {
+		dev_err(dev, "Cannot get the clk dmc_clk\n");
+		return PTR_ERR(data->clk);
+	};
+
+	/* try to find the optional reference to the pmu syscon */
+	node = of_parse_phandle(np, "rockchip,pmu", 0);
+	if (node) {
+		data->regmap_pmu = syscon_node_to_regmap(node);
+		if (IS_ERR(data->regmap_pmu))
+			return PTR_ERR(data->regmap_pmu);
+	}
+	data->dev = dev;
+
+	desc = devm_kzalloc(dev, sizeof(*desc), GFP_KERNEL);
+	if (!desc)
+		return -ENOMEM;
+
+	desc->ops = &rockchip_dfi_ops;
+	desc->driver_data = data;
+	desc->name = np->name;
+	data->desc = desc;
+
+	data->edev = devm_devfreq_event_add_edev(&pdev->dev, desc);
+	if (IS_ERR(data->edev)) {
+		dev_err(&pdev->dev,
+			"failed to add devfreq-event device\n");
+		return PTR_ERR(data->edev);
+	}
+
+	platform_set_drvdata(pdev, data);
+
+	return 0;
+}
+
+static struct platform_driver rockchip_dfi_driver = {
+	.probe	= rockchip_dfi_probe,
+	.driver = {
+		.name	= "rockchip-dfi",
+		.of_match_table = rockchip_dfi_id_match,
+	},
+};
+module_platform_driver(rockchip_dfi_driver);
+
+MODULE_LICENSE("GPL v2");
+MODULE_AUTHOR("Lin Huang <[e-mail]>");
+MODULE_DESCRIPTION("Rockchip DFI driver");