Date:   Tue, 8 Sep 2020 15:35:46 +0800
From:   Hector Yuan <hector.yuan@...iatek.com>
To:     <linux-mediatek@...ts.infradead.org>,
        <linux-arm-kernel@...ts.infradead.org>, <linux-pm@...r.kernel.org>,
        <devicetree@...r.kernel.org>,
        "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Viresh Kumar <viresh.kumar@...aro.org>,
        Rob Herring <robh+dt@...nel.org>
CC:     <linux-kernel@...r.kernel.org>, <wsd_upstream@...iatek.com>,
        <hector.yuan@...iatek.com>
Subject: [PATCH v4 1/2] cpufreq: mediatek-hw: Add support for Mediatek cpufreq HW driver

From: "Hector.Yuan" <hector.yuan@...iatek.com>

Add MT6779 cpufreq HW support.

Signed-off-by: Hector.Yuan <hector.yuan@...iatek.com>
---
 drivers/cpufreq/Kconfig.arm           |   12 ++
 drivers/cpufreq/Makefile              |    1 +
 drivers/cpufreq/mediatek-cpufreq-hw.c |  294 +++++++++++++++++++++++++++++++++
 3 files changed, 307 insertions(+)
 create mode 100644 drivers/cpufreq/mediatek-cpufreq-hw.c

diff --git a/drivers/cpufreq/Kconfig.arm b/drivers/cpufreq/Kconfig.arm
index c6cbfc8..8e58c12 100644
--- a/drivers/cpufreq/Kconfig.arm
+++ b/drivers/cpufreq/Kconfig.arm
@@ -121,6 +121,18 @@ config ARM_MEDIATEK_CPUFREQ
 	help
 	  This adds the CPUFreq driver support for MediaTek SoCs.
 
+config ARM_MEDIATEK_CPUFREQ_HW
+	tristate "MediaTek CPUFreq HW driver"
+	depends on ARCH_MEDIATEK || COMPILE_TEST
+	default m
+	help
+	  Support for the CPUFreq HW driver.
+	  Some MediaTek chipsets have a HW engine to offload the steps
+	  necessary for changing the frequency of the CPUs. Firmware loaded
+	  in this engine exposes a programming interface to the OS.
+	  The driver implements the cpufreq interface for this HW engine.
+	  Say Y if you want to support CPUFreq HW.
+
 config ARM_OMAP2PLUS_CPUFREQ
 	bool "TI OMAP2+"
 	depends on ARCH_OMAP2PLUS
diff --git a/drivers/cpufreq/Makefile b/drivers/cpufreq/Makefile
index f6670c4..dc1f371 100644
--- a/drivers/cpufreq/Makefile
+++ b/drivers/cpufreq/Makefile
@@ -57,6 +57,7 @@ obj-$(CONFIG_ARM_IMX6Q_CPUFREQ)		+= imx6q-cpufreq.o
 obj-$(CONFIG_ARM_IMX_CPUFREQ_DT)	+= imx-cpufreq-dt.o
 obj-$(CONFIG_ARM_KIRKWOOD_CPUFREQ)	+= kirkwood-cpufreq.o
 obj-$(CONFIG_ARM_MEDIATEK_CPUFREQ)	+= mediatek-cpufreq.o
+obj-$(CONFIG_ARM_MEDIATEK_CPUFREQ_HW)	+= mediatek-cpufreq-hw.o
 obj-$(CONFIG_MACH_MVEBU_V7)		+= mvebu-cpufreq.o
 obj-$(CONFIG_ARM_OMAP2PLUS_CPUFREQ)	+= omap-cpufreq.o
 obj-$(CONFIG_ARM_PXA2xx_CPUFREQ)	+= pxa2xx-cpufreq.o
diff --git a/drivers/cpufreq/mediatek-cpufreq-hw.c b/drivers/cpufreq/mediatek-cpufreq-hw.c
new file mode 100644
index 0000000..61040b8
--- /dev/null
+++ b/drivers/cpufreq/mediatek-cpufreq-hw.c
@@ -0,0 +1,294 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (c) 2020 MediaTek Inc.
+ */
+
+#include <linux/bitfield.h>
+#include <linux/cpufreq.h>
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/of_address.h>
+#include <linux/of_platform.h>
+#include <linux/slab.h>
+
+#define LUT_MAX_ENTRIES			32U
+#define LUT_FREQ			GENMASK(11, 0)
+#define LUT_ROW_SIZE			0x4
+
+enum {
+	REG_LUT_TABLE,
+	REG_ENABLE,
+	REG_PERF_STATE,
+
+	REG_ARRAY_SIZE,
+};
+
+struct cpufreq_mtk {
+	struct cpufreq_frequency_table *table;
+	void __iomem *reg_bases[REG_ARRAY_SIZE];
+	cpumask_t related_cpus;
+};
+
+static const u16 cpufreq_mtk_offsets[REG_ARRAY_SIZE] = {
+	[REG_LUT_TABLE]		= 0x0,
+	[REG_ENABLE]	= 0x84,
+	[REG_PERF_STATE]	= 0x88,
+};
+
+static struct cpufreq_mtk *mtk_freq_domain_map[NR_CPUS];
+
+static int mtk_cpufreq_hw_target_index(struct cpufreq_policy *policy,
+				       unsigned int index)
+{
+	struct cpufreq_mtk *c = policy->driver_data;
+
+	writel_relaxed(index, c->reg_bases[REG_PERF_STATE]);
+	arch_set_freq_scale(policy->related_cpus,
+			    policy->freq_table[index].frequency,
+			    policy->cpuinfo.max_freq);
+
+	return 0;
+}
+
+static unsigned int mtk_cpufreq_hw_get(unsigned int cpu)
+{
+	struct cpufreq_mtk *c;
+	struct cpufreq_policy *policy;
+	unsigned int index;
+
+	policy = cpufreq_cpu_get_raw(cpu);
+	if (!policy)
+		return 0;
+
+	c = policy->driver_data;
+
+	index = readl_relaxed(c->reg_bases[REG_PERF_STATE]);
+	index = min(index, LUT_MAX_ENTRIES - 1);
+
+	return policy->freq_table[index].frequency;
+}
+
+static int mtk_cpufreq_hw_cpu_init(struct cpufreq_policy *policy)
+{
+	struct cpufreq_mtk *c;
+	struct device *cpu_dev;
+
+	cpu_dev = get_cpu_device(policy->cpu);
+	if (!cpu_dev) {
+		pr_err("%s: failed to get cpu%d device\n", __func__,
+		       policy->cpu);
+		return -ENODEV;
+	}
+
+	c = mtk_freq_domain_map[policy->cpu];
+	if (!c) {
+		pr_err("No scaling support for CPU%d\n", policy->cpu);
+		return -ENODEV;
+	}
+
+	cpumask_copy(policy->cpus, &c->related_cpus);
+
+	policy->freq_table = c->table;
+	policy->driver_data = c;
+
+	/* HW should be in enabled state to proceed now */
+	writel_relaxed(0x1, c->reg_bases[REG_ENABLE]);
+
+	return 0;
+}
+
+static struct freq_attr *mtk_cpufreq_hw_attr[] = {
+	&cpufreq_freq_attr_scaling_available_freqs,
+	NULL
+};
+
+static struct cpufreq_driver cpufreq_mtk_hw_driver = {
+	.flags		= CPUFREQ_STICKY | CPUFREQ_NEED_INITIAL_FREQ_CHECK |
+			  CPUFREQ_HAVE_GOVERNOR_PER_POLICY,
+	.verify		= cpufreq_generic_frequency_table_verify,
+	.target_index	= mtk_cpufreq_hw_target_index,
+	.get		= mtk_cpufreq_hw_get,
+	.init		= mtk_cpufreq_hw_cpu_init,
+	.name		= "mtk-cpufreq-hw",
+	.attr		= mtk_cpufreq_hw_attr,
+};
+
+static int mtk_cpufreq_hw_opp_create(struct platform_device *pdev,
+				     struct cpufreq_mtk *c)
+{
+	struct device *dev = &pdev->dev;
+	void __iomem *base_table;
+	u32 data, i, freq, prev_freq = 0;
+
+	c->table = devm_kcalloc(dev, LUT_MAX_ENTRIES + 1,
+				sizeof(*c->table), GFP_KERNEL);
+	if (!c->table)
+		return -ENOMEM;
+
+	base_table = c->reg_bases[REG_LUT_TABLE];
+
+	for (i = 0; i < LUT_MAX_ENTRIES; i++) {
+		data = readl_relaxed(base_table + (i * LUT_ROW_SIZE));
+		freq = FIELD_GET(LUT_FREQ, data) * 1000;
+
+		if (freq == prev_freq)
+			break;
+
+		c->table[i].frequency = freq;
+
+		dev_dbg(dev, "index=%d freq=%d\n",
+			i, c->table[i].frequency);
+
+		prev_freq = freq;
+	}
+
+	c->table[i].frequency = CPUFREQ_TABLE_END;
+
+	return 0;
+}
+
+static int mtk_get_related_cpus(int index, struct cpumask *m)
+{
+	struct device_node *cpu_np;
+	struct of_phandle_args args;
+	int cpu, ret;
+
+	for_each_possible_cpu(cpu) {
+		cpu_np = of_cpu_device_node_get(cpu);
+		if (!cpu_np)
+			continue;
+
+		ret = of_parse_phandle_with_args(cpu_np, "mtk-freq-domain",
+						 "#freq-domain-cells", 0,
+						 &args);
+		of_node_put(cpu_np);
+		if (ret < 0)
+			continue;
+
+		if (index == args.args[0])
+			cpumask_set_cpu(cpu, m);
+	}
+
+	return 0;
+}
+
+static int mtk_cpu_resources_init(struct platform_device *pdev,
+				  unsigned int cpu, int index)
+{
+	struct cpufreq_mtk *c;
+	struct resource *res;
+	struct device *dev = &pdev->dev;
+	const u16 *offsets;
+	int ret, i, cpu_r;
+	void __iomem *base;
+
+	if (mtk_freq_domain_map[cpu])
+		return 0;
+
+	c = devm_kzalloc(dev, sizeof(*c), GFP_KERNEL);
+	if (!c)
+		return -ENOMEM;
+
+	offsets = of_device_get_match_data(&pdev->dev);
+	if (!offsets)
+		return -EINVAL;
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, index);
+	base = devm_ioremap_resource(dev, res);
+	if (IS_ERR(base))
+		return PTR_ERR(base);
+
+	for (i = REG_LUT_TABLE; i < REG_ARRAY_SIZE; i++)
+		c->reg_bases[i] = base + offsets[i];
+
+	ret = mtk_get_related_cpus(index, &c->related_cpus);
+	if (ret) {
+		dev_err(dev, "Domain-%d failed to get related CPUs\n", index);
+		return ret;
+	}
+
+	ret = mtk_cpufreq_hw_opp_create(pdev, c);
+	if (ret) {
+		dev_err(dev, "Domain-%d failed to create OPP\n", index);
+		return ret;
+	}
+
+	for_each_cpu(cpu_r, &c->related_cpus)
+		mtk_freq_domain_map[cpu_r] = c;
+
+	return 0;
+}
+
+static int mtk_resources_init(struct platform_device *pdev)
+{
+	struct device_node *cpu_np;
+	struct of_phandle_args args;
+	unsigned int cpu;
+	int ret;
+
+	for_each_possible_cpu(cpu) {
+		cpu_np = of_cpu_device_node_get(cpu);
+		if (!cpu_np) {
+			dev_dbg(&pdev->dev, "Failed to get cpu %d device\n",
+				cpu);
+			continue;
+		}
+
+		ret = of_parse_phandle_with_args(cpu_np, "mtk-freq-domain",
+						 "#freq-domain-cells", 0, &args);
+		if (ret < 0)
+			return ret;
+
+		ret = mtk_cpu_resources_init(pdev, cpu, args.args[0]);
+		if (ret)
+			return ret;
+	}
+
+	return 0;
+}
+
+static int mtk_cpufreq_hw_driver_probe(struct platform_device *pdev)
+{
+	int ret;
+
+	/* Get the bases of cpufreq for domains */
+	ret = mtk_resources_init(pdev);
+	if (ret) {
+		dev_err(&pdev->dev, "CPUFreq resource init failed\n");
+		return ret;
+	}
+
+	ret = cpufreq_register_driver(&cpufreq_mtk_hw_driver);
+	if (ret) {
+		dev_err(&pdev->dev, "CPUFreq HW driver failed to register\n");
+		return ret;
+	}
+
+	dev_dbg(&pdev->dev, "Mediatek CPUFreq HW driver initialized\n");
+	of_platform_populate(pdev->dev.of_node, NULL, NULL, &pdev->dev);
+
+	return 0;
+}
+
+static const struct of_device_id mtk_cpufreq_hw_match[] = {
+	{ .compatible = "mediatek,cpufreq-hw", .data = &cpufreq_mtk_offsets },
+	{}
+};
+
+static struct platform_driver mtk_cpufreq_hw_driver = {
+	.probe = mtk_cpufreq_hw_driver_probe,
+	.driver = {
+		.name = "mtk-cpufreq-hw",
+		.of_match_table = mtk_cpufreq_hw_match,
+	},
+};
+
+static int __init mtk_cpufreq_hw_init(void)
+{
+	return platform_driver_register(&mtk_cpufreq_hw_driver);
+}
+subsys_initcall(mtk_cpufreq_hw_init);
+
+MODULE_DESCRIPTION("mtk CPUFREQ HW Driver");
+MODULE_LICENSE("GPL v2");
-- 
1.7.9.5

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