[PATCH v6] cpufreq: mediatek-hw: Add support for Mediatek cpufreq HW driver

[PATCH v6] cpufreq: mediatek-hw: Add support for Mediatek cpufreq HW driver

[Hector Yuan]

The CPUfreq HW present in some Mediatek chipsets offloads the steps necessary for changing the frequency of CPUs. 
The driver implements the cpufreq driver interface for this hardware engine. 

This patch depends on the MT6779 DTS patch submitted by Hanks Chen
 https://lkml.org/lkml/2020/8/4/1094


Hector.Yuan (2):
  cpufreq: mediatek-hw: Add support for Mediatek cpufreq HW driver
  dt-bindings: cpufreq: add bindings for MediaTek cpufreq HW

 .../bindings/cpufreq/cpufreq-mediatek-hw.yaml      |  141 ++++++++++
 drivers/cpufreq/Kconfig.arm                        |   12 +
 drivers/cpufreq/Makefile                           |    1 +
 drivers/cpufreq/mediatek-cpufreq-hw.c              |  283 ++++++++++++++++++++
 4 files changed, 437 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/cpufreq/cpufreq-mediatek-hw.yaml
 create mode 100644 drivers/cpufreq/mediatek-cpufreq-hw.c

[PATCH v6 1/2] cpufreq: mediatek-hw: Add support for Mediatek cpufreq HW driver

[Hector Yuan]

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

Add MT6779 cpufreq HW support.

Signed-off-by: Hector.Yuan <hector.yuan@mediatek.com>
---
 drivers/cpufreq/Kconfig.arm           |   12 ++
 drivers/cpufreq/Makefile              |    1 +
 drivers/cpufreq/mediatek-cpufreq-hw.c |  283 +++++++++++++++++++++++++++++++++
 3 files changed, 296 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..ce6b592
--- /dev/null
+++ b/drivers/cpufreq/mediatek-cpufreq-hw.c
@@ -0,0 +1,283 @@
+// 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]);
+
+	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 = mtk_freq_domain_map[cpu];
+
+	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;
+
+	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 int mtk_cpufreq_hw_cpu_exit(struct cpufreq_policy *policy)
+{
+	struct cpufreq_mtk *c;
+
+	c = mtk_freq_domain_map[policy->cpu];
+	if (!c) {
+		pr_err("No scaling support for CPU%d\n", policy->cpu);
+		return -ENODEV;
+	}
+
+	/* HW should be in paused state now */
+	writel_relaxed(0x0, c->reg_bases[REG_ENABLE]);
+
+	return 0;
+}
+
+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		= cpufreq_generic_attr,
+};
+
+static int mtk_cpu_create_freq_table(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 cpufreq_mtk *c)
+{
+	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, &c->related_cpus);
+			mtk_freq_domain_map[cpu] = c;
+		}
+	}
+
+	return 0;
+}
+
+static int mtk_cpu_resources_init(struct platform_device *pdev,
+				  unsigned int cpu, int index,
+				  const u16 *offsets)
+{
+	struct cpufreq_mtk *c;
+	struct resource *res;
+	struct device *dev = &pdev->dev;
+	int ret, i;
+	void __iomem *base;
+
+	if (mtk_freq_domain_map[cpu])
+		return 0;
+
+	c = devm_kzalloc(dev, sizeof(*c), GFP_KERNEL);
+	if (!c)
+		return -ENOMEM;
+
+	base = devm_platform_ioremap_resource(pdev, index);
+	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);
+	if (ret) {
+		dev_err(dev, "Domain-%d failed to get related CPUs\n", index);
+		return ret;
+	}
+
+	ret = mtk_cpu_create_freq_table(pdev, c);
+	if (ret) {
+		dev_err(dev, "Domain-%d failed to create freq table\n", index);
+		return ret;
+	}
+
+	return 0;
+}
+
+static int mtk_cpufreq_hw_driver_probe(struct platform_device *pdev)
+{
+	struct device_node *cpu_np;
+	struct of_phandle_args args;
+	const u16 *offsets;
+	unsigned int cpu;
+	int ret;
+
+	offsets = of_device_get_match_data(&pdev->dev);
+	if (!offsets)
+		return -EINVAL;
+
+	for_each_possible_cpu(cpu) {
+		cpu_np = of_cpu_device_node_get(cpu);
+		if (!cpu_np) {
+			dev_err(&pdev->dev, "Failed to get cpu %d device\n",
+				cpu);
+			return -ENODEV;
+		}
+
+		ret = of_parse_phandle_with_args(cpu_np, "mtk-freq-domain",
+						 "#freq-domain-cells", 0,
+						 &args);
+		if (ret < 0)
+			return ret;
+
+		/* Get the bases of cpufreq for domains */
+		ret = mtk_cpu_resources_init(pdev, cpu, args.args[0], offsets);
+		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;
+	}
+
+	return 0;
+}
+
+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", .data = &cpufreq_mtk_offsets },
+	{}
+};
+
+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,
+	},
+};
+
+module_platform_driver(mtk_cpufreq_hw_driver);
+
+MODULE_DESCRIPTION("mtk CPUFREQ HW Driver");
+MODULE_LICENSE("GPL v2");
-- 
1.7.9.5

[PATCH v6 2/2] dt-bindings: cpufreq: add bindings for MediaTek cpufreq HW

[Hector Yuan]

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

Add devicetree bindings for MediaTek HW driver.

Signed-off-by: Hector.Yuan <hector.yuan@mediatek.com>
---
 .../bindings/cpufreq/cpufreq-mediatek-hw.yaml      |  141 ++++++++++++++++++++
 1 file changed, 141 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/cpufreq/cpufreq-mediatek-hw.yaml

diff --git a/Documentation/devicetree/bindings/cpufreq/cpufreq-mediatek-hw.yaml b/Documentation/devicetree/bindings/cpufreq/cpufreq-mediatek-hw.yaml
new file mode 100644
index 0000000..118a163
--- /dev/null
+++ b/Documentation/devicetree/bindings/cpufreq/cpufreq-mediatek-hw.yaml
@@ -0,0 +1,141 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/cpufreq/cpufreq-mediatek-hw.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: MediaTek's CPUFREQ Bindings
+
+maintainers:
+  - Hector Yuan <hector.yuan@mediatek.com>
+
+description:
+  CPUFREQ HW is a hardware engine used by MediaTek
+  SoCs to manage frequency in hardware. It is capable of controlling frequency
+  for multiple clusters.
+
+properties:
+  compatible:
+    const: "mediatek,cpufreq-hw"
+
+  reg:
+    minItems: 1
+    maxItems: 2
+    description: |
+      Addresses and sizes for the memory of the HW bases in each frequency domain.
+
+  reg-names:
+    items:
+      - const: "freq-domain0"
+      - const: "freq-domain1"
+    description: |
+      Frequency domain name. i.e.
+      "freq-domain0", "freq-domain1".
+
+  "#freq-domain-cells":
+    const: 1
+    description: |
+      Number of cells in a freqency domain specifier.
+
+  mtk-freq-domain:
+    maxItems: 1
+    description: |
+      Define this cpu belongs to which frequency domain. i.e.
+      cpu0-3 belong to frequency domain0,
+      cpu4-6 belong to frequency domain1.
+
+required:
+  - compatible
+  - reg
+  - reg-names
+  - "#freq-domain-cells"
+
+examples:
+  - |
+    cpus {
+            #address-cells = <1>;
+            #size-cells = <0>;
+
+            cpu0: cpu@0 {
+                device_type = "cpu";
+                compatible = "arm,cortex-a55";
+                enable-method = "psci";
+                mtk-freq-domain = <&cpufreq_hw 0>;
+                reg = <0x000>;
+            };
+
+            cpu1: cpu@1 {
+                device_type = "cpu";
+                compatible = "arm,cortex-a55";
+                enable-method = "psci";
+                mtk-freq-domain = <&cpufreq_hw 0>;
+                reg = <0x100>;
+            };
+
+            cpu2: cpu@2 {
+                device_type = "cpu";
+                compatible = "arm,cortex-a55";
+                enable-method = "psci";
+                mtk-freq-domain = <&cpufreq_hw 0>;
+                reg = <0x200>;
+            };
+
+            cpu3: cpu@3 {
+                device_type = "cpu";
+                compatible = "arm,cortex-a55";
+                enable-method = "psci";
+                mtk-freq-domain = <&cpufreq_hw 0>;
+                reg = <0x300>;
+            };
+
+            cpu4: cpu@4 {
+                device_type = "cpu";
+                compatible = "arm,cortex-a55";
+                enable-method = "psci";
+                mtk-freq-domain = <&cpufreq_hw 1>;
+                reg = <0x400>;
+            };
+
+            cpu5: cpu@5 {
+                device_type = "cpu";
+                compatible = "arm,cortex-a55";
+                enable-method = "psci";
+                mtk-freq-domain = <&cpufreq_hw 1>;
+                reg = <0x500>;
+            };
+
+            cpu6: cpu@6 {
+                device_type = "cpu";
+                compatible = "arm,cortex-a75";
+                enable-method = "psci";
+                mtk-freq-domain = <&cpufreq_hw 1>;
+                reg = <0x600>;
+            };
+
+            cpu7: cpu@7 {
+                device_type = "cpu";
+                compatible = "arm,cortex-a75";
+                enable-method = "psci";
+                mtk-freq-domain = <&cpufreq_hw 1>;
+                reg = <0x700>;
+            };
+    };
+
+    /* ... */
+
+    soc {
+        #address-cells = <2>;
+        #size-cells = <2>;
+
+        cpufreq_hw: cpufreq@11bc00 {
+            compatible = "mediatek,cpufreq-hw";
+            reg = <0 0x11bc10 0 0x8c>,
+               <0 0x11bca0 0 0x8c>;
+            reg-names = "freq-domain0", "freq-domain1";
+            #freq-domain-cells = <1>;
+        };
+    };
+
+
+
+
-- 
1.7.9.5

Re: [PATCH v6 1/2] cpufreq: mediatek-hw: Add support for Mediatek cpufreq HW driver

[Viresh Kumar]

On 09-09-20, 21:34, Hector Yuan wrote:
> +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;

Why didn't you drop policy as we discussed in previous version ?

> +	c = mtk_freq_domain_map[cpu];
> +
> +	index = readl_relaxed(c->reg_bases[REG_PERF_STATE]);
> +	index = min(index, LUT_MAX_ENTRIES - 1);
> +
> +	return policy->freq_table[index].frequency;

policy->freq_table and c->table are same, isn't it ?

> +}
> +
> +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,
> +	},
> +};
> +

Remove this blank line.

> +module_platform_driver(mtk_cpufreq_hw_driver);
> +
> +MODULE_DESCRIPTION("mtk CPUFREQ HW Driver");

Maybe write this is "Mediatek cpufreq-hw driver" ?

> +MODULE_LICENSE("GPL v2");
> -- 
> 1.7.9.5

-- 
viresh

Re: [PATCH v6 1/2] cpufreq: mediatek-hw: Add support for Mediatek cpufreq HW driver

[Hector Yuan]

On Thu, 2020-09-10 at 09:12 +0530, Viresh Kumar wrote:
> On 09-09-20, 21:34, Hector Yuan wrote:
> > +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;
> 
> Why didn't you drop policy as we discussed in previous version ?
> 
Sorry I missed that. Thank you.
> > +	c = mtk_freq_domain_map[cpu];
> > +
> > +	index = readl_relaxed(c->reg_bases[REG_PERF_STATE]);
> > +	index = min(index, LUT_MAX_ENTRIES - 1);
> > +
> > +	return policy->freq_table[index].frequency;
> 
> policy->freq_table and c->table are same, isn't it ?
> 
Yes, you are right.
> > +}
> > +
> > +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,
> > +	},
> > +};
> > +
> 
> Remove this blank line.
> 
OK
> > +module_platform_driver(mtk_cpufreq_hw_driver);
> > +
> > +MODULE_DESCRIPTION("mtk CPUFREQ HW Driver");
> 
> Maybe write this is "Mediatek cpufreq-hw driver" ?
> 
OK
> > +MODULE_LICENSE("GPL v2");
> > -- 
> > 1.7.9.5
>