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

[Hector Yuan]

On Mon, 2020-08-24 at 15:36 +0530, Viresh Kumar wrote:
> On 13-08-20, 15:07, Hector Yuan wrote:
> > From: "Hector.Yuan" <hector.yuan@xxxxxxxxxxxx>
> > 
> > Add MT6779 cpufreq HW support.
> > 
> > Signed-off-by: Hector.Yuan <hector.yuan@xxxxxxxxxxxx>
> > ---
> >  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
> 
> What about a 'default m' in Kconfig itself ?
> OK, will update in V3.
> >  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;
> 
> Use cpufreq_driver->driver_data for this, it is already used in other
> drivers for similar use.
> OK, I see.will update in V3.
> > +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,
> 
> This routine needs to be named better, it is creating the cpufreq
> table after all.
> OK, will update in V3. rename to xxx_opp_create.
> > +				   struct cpufreq_policy *policy,
> > +				   void __iomem *base)
> 
> Please make sure checkpatch --strict doesn't give any errors.
> 
> > +{
> > +	u32 data;
> > +	u32 freq, volt, prev_freq = 0;
> 
> Merge these two..
> OK
> > +	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);
> 
> Why are you adding OPPs here and rather why using OPP specific stuff
> at all in the driver ?
> yes, the opp information is read from CPU HW engine.Then add it to the CPU dev OPP one by one.  
> > +			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",
> 
> Where are bindings of this node and how does this look ?
> Can refer to the same patch series, I split it to another patch.Each cpu will be group into one frequency domain for the CPU DVFS. 
> > +						 "#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
>