[PATCH v2 1/2] cpufreq: mediatek-hw: Add support for Mediatek cpufreq HW driver

[Hector Yuan <hector.yuan@mediatek.com>]

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

Add MT6779 cpufreq HW support.

Signed-off-by: Hector.Yuan <hector.yuan@mediatek.com>
---
 arch/arm64/configs/defconfig          |    1 +
 drivers/cpufreq/Kconfig.arm           |   11 ++
 drivers/cpufreq/Makefile              |    1 +
 drivers/cpufreq/mediatek-cpufreq-hw.c |  255 +++++++++++++++++++++++++++++++++
 4 files changed, 268 insertions(+)
 create mode 100644 drivers/cpufreq/mediatek-cpufreq-hw.c

diff --git a/arch/arm64/configs/defconfig b/arch/arm64/configs/defconfig
index 883e8ba..866a1bf 100644
--- a/arch/arm64/configs/defconfig
+++ b/arch/arm64/configs/defconfig
@@ -86,6 +86,7 @@ CONFIG_CPUFREQ_DT=y
 CONFIG_ACPI_CPPC_CPUFREQ=m
 CONFIG_ARM_ALLWINNER_SUN50I_CPUFREQ_NVMEM=m
 CONFIG_ARM_ARMADA_37XX_CPUFREQ=y
+CONFIG_ARM_MEDIATEK_CPUFREQ_HW=m
 CONFIG_ARM_SCPI_CPUFREQ=y
 CONFIG_ARM_IMX_CPUFREQ_DT=m
 CONFIG_ARM_QCOM_CPUFREQ_NVMEM=y
diff --git a/drivers/cpufreq/Kconfig.arm b/drivers/cpufreq/Kconfig.arm
index c6cbfc8..81f1cc1 100644
--- a/drivers/cpufreq/Kconfig.arm
+++ b/drivers/cpufreq/Kconfig.arm
@@ -121,6 +121,17 @@ 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
+	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..6752db9
--- /dev/null
+++ b/drivers/cpufreq/mediatek-cpufreq-hw.c
@@ -0,0 +1,255 @@
+// 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/pm_opp.h>
+#include <linux/slab.h>
+
+#define LUT_MAX_ENTRIES			32U
+#define LUT_FREQ			GENMASK(11, 0)
+#define LUT_VOLT			GENMASK(28, 12)
+#define LUT_ROW_SIZE			0x4
+
+/* Register offsets */
+#define REG_ENABLE			0x84
+#define REG_PERF_STATE		0x88
+
+static struct platform_device *global_pdev;
+static int mtk_cpufreq_hw_target_index(struct cpufreq_policy *policy,
+				       unsigned int index)
+{
+	void __iomem *perf_state_reg = policy->driver_data;
+	unsigned long freq = policy->freq_table[index].frequency;
+
+	writel_relaxed(index, perf_state_reg);
+	arch_set_freq_scale(policy->related_cpus, freq,
+			    policy->cpuinfo.max_freq);
+	return 0;
+}
+
+static unsigned int mtk_cpufreq_hw_get(unsigned int cpu)
+{
+	void __iomem *perf_state_reg;
+	struct cpufreq_policy *policy;
+	unsigned int index;
+
+	policy = cpufreq_cpu_get_raw(cpu);
+	if (!policy)
+		return 0;
+
+	perf_state_reg = policy->driver_data;
+
+	index = readl_relaxed(perf_state_reg);
+	index = min(index, LUT_MAX_ENTRIES - 1);
+
+	return policy->freq_table[index].frequency;
+}
+
+static int mtk_cpufreq_hw_read_lut(struct device *cpu_dev,
+				   struct cpufreq_policy *policy,
+				   void __iomem *base)
+{
+	u32 data;
+	u32 freq, volt, prev_freq = 0;
+	int i = 0;
+	struct cpufreq_frequency_table	*table;
+
+	table = kcalloc(LUT_MAX_ENTRIES + 1, sizeof(*table), GFP_KERNEL);
+	if (!table)
+		return -ENOMEM;
+
+	for (i = 0; i < LUT_MAX_ENTRIES; i++) {
+		data = readl_relaxed(base + (i * LUT_ROW_SIZE));
+		freq = FIELD_GET(LUT_FREQ, data) * 1000;
+		volt = FIELD_GET(LUT_VOLT, data);
+		if (freq != prev_freq) {
+			table[i].frequency = freq;
+			dev_pm_opp_add(cpu_dev, freq * 1000, volt);
+			dev_dbg(cpu_dev, "index=%d freq=%d, volt=%d\n", i,
+				freq, volt);
+		} else {
+			break;
+		}
+		prev_freq = freq;
+	}
+	table[i].frequency = CPUFREQ_TABLE_END;
+	policy->freq_table = table;
+	dev_pm_opp_set_sharing_cpus(cpu_dev, policy->cpus);
+
+	return 0;
+}
+
+static void 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);
+	}
+}
+
+static int mtk_cpufreq_hw_cpu_init(struct cpufreq_policy *policy)
+{
+	struct device *dev = &global_pdev->dev;
+	struct of_phandle_args args;
+	struct device_node *cpu_np;
+	struct device *cpu_dev;
+	struct resource *res;
+	void __iomem *base;
+	int ret, index;
+
+	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;
+	}
+
+	cpu_np = of_cpu_device_node_get(policy->cpu);
+	if (!cpu_np)
+		return -EINVAL;
+
+	ret = of_parse_phandle_with_args(cpu_np, "mtk,freq-domain",
+					 "#freq-domain-cells", 0, &args);
+	of_node_put(cpu_np);
+	if (ret)
+		return ret;
+
+	index = args.args[0];
+	res = platform_get_resource(global_pdev, IORESOURCE_MEM, index);
+	if (!res)
+		return -ENODEV;
+	base = devm_ioremap(dev, res->start, resource_size(res));
+	if (!base)
+		return -ENOMEM;
+
+	mtk_get_related_cpus(index, policy->cpus);
+	if (!cpumask_weight(policy->cpus)) {
+		dev_err(dev, "Domain-%d failed to get related CPUs\n", index);
+		ret = -ENOENT;
+		goto error;
+	}
+
+	policy->driver_data = base + REG_PERF_STATE;
+	ret = mtk_cpufreq_hw_read_lut(cpu_dev, policy, base);
+	if (ret) {
+		dev_err(dev, "Domain-%d failed to read LUT\n", index);
+		goto error;
+	}
+
+	ret = dev_pm_opp_get_opp_count(cpu_dev);
+	if (ret <= 0) {
+		dev_err(cpu_dev, "Failed to add OPPs\n");
+		ret = -ENODEV;
+		goto error;
+	}
+
+	dev_pm_opp_of_register_em(policy->cpus);
+
+	/* HW should be in enabled state to proceed now */
+	writel_relaxed(0x1, (base + REG_ENABLE));
+	return 0;
+error:
+	devm_iounmap(dev, base);
+	return ret;
+}
+
+static int mtk_cpufreq_hw_cpu_exit(struct cpufreq_policy *policy)
+{
+	struct device *cpu_dev = get_cpu_device(policy->cpu);
+	void __iomem *base = policy->driver_data - REG_PERF_STATE;
+
+	dev_pm_opp_remove_all_dynamic(cpu_dev);
+	kfree(policy->freq_table);
+	devm_iounmap(&global_pdev->dev, base);
+
+	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,
+	.exit		= mtk_cpufreq_hw_cpu_exit,
+	.name		= "mtk-cpufreq-hw",
+	.attr		= mtk_cpufreq_hw_attr,
+};
+
+static int mtk_cpufreq_hw_driver_probe(struct platform_device *pdev)
+{
+	int ret;
+
+	global_pdev = pdev;
+	ret = cpufreq_register_driver(&cpufreq_mtk_hw_driver);
+	if (ret)
+		dev_err(&pdev->dev, "CPUFreq HW driver failed to register\n");
+	else
+		dev_dbg(&pdev->dev, "mtk CPUFreq HW driver initialized\n");
+
+	return ret;
+}
+
+static int mtk_cpufreq_hw_driver_remove(struct platform_device *pdev)
+{
+	return cpufreq_unregister_driver(&cpufreq_mtk_hw_driver);
+}
+
+static const struct of_device_id mtk_cpufreq_hw_match[] = {
+	{ .compatible = "mediatek,cpufreq-hw" },
+	{}
+};
+MODULE_DEVICE_TABLE(of, mtk_cpufreq_hw_match);
+
+static struct platform_driver mtk_cpufreq_hw_driver = {
+	.probe = mtk_cpufreq_hw_driver_probe,
+	.remove = mtk_cpufreq_hw_driver_remove,
+	.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);
+}
+postcore_initcall(mtk_cpufreq_hw_init);
+
+static void __exit mtk_cpufreq_hw_exit(void)
+{
+	platform_driver_unregister(&mtk_cpufreq_hw_driver);
+}
+module_exit(mtk_cpufreq_hw_exit);
+
+MODULE_DESCRIPTION("mtk CPUFREQ HW Driver");
+MODULE_LICENSE("GPL v2");
-- 
1.7.9.5