Re: [PATCH v2 4/4] devfreq: add mediatek cci devfreq

[andrew-sh.cheng <andrew-sh.cheng@mediatek.com>]

On Tue, 2019-04-16 at 18:05 +0900, Chanwoo Choi wrote:
> Hi Andrew-sh.Cheng,
> 
> Please add the dt-binding documentation.
> 
> On 19. 3. 29. 오후 3:46, Andrew-sh.Cheng wrote:
> > This adds a devfreq driver for the Cache Coherent Interconnect (CCI)
> > of the Mediatek MT8183.
> > 
> > On the MT8183 the CCI is supplied by the same regulator as the LITTLE
> > cores. The driver is notified when the regulator voltage changes
> > (driven by cpufreq) and adjusts the CCI frequency to the maximum
> > possible value.
> > 
> > Signed-off-by: Andrew-sh.Cheng <andrew-sh.cheng@mediatek.com>
> > ---
> >  drivers/devfreq/Kconfig              |  10 ++
> >  drivers/devfreq/Makefile             |   1 +
> >  drivers/devfreq/mt8183-cci-devfreq.c | 235 +++++++++++++++++++++++++++++++++++
> >  3 files changed, 246 insertions(+)
> >  create mode 100644 drivers/devfreq/mt8183-cci-devfreq.c
> > 
> > diff --git a/drivers/devfreq/Kconfig b/drivers/devfreq/Kconfig
> > index 6a172d3..da2f8ec 100644
> > --- a/drivers/devfreq/Kconfig
> > +++ b/drivers/devfreq/Kconfig
> > @@ -91,6 +91,16 @@ config ARM_EXYNOS_BUS_DEVFREQ
> >  	  and adjusts the operating frequencies and voltages with OPP support.
> >  	  This does not yet operate with optimal voltages.
> >  
> > +config ARM_MT8183_CCI_DEVFREQ
> > +	tristate "MT8183 CCI DEVFREQ Driver"
> > +	depends on ARM_MEDIATEK_CPUFREQ
> > +	help
> > +		This adds a devfreq driver for Cache Coherent Interconnect
> > +		of Mediatek MT8183, which is shared the same regulator
> > +		with cpu cluster.
> > +		It can track buck voltage and update a proper cci frequency.
> > +		Use notification to get regulator status.
> > +
> >  config ARM_TEGRA_DEVFREQ
> >  	tristate "Tegra DEVFREQ Driver"
> >  	depends on ARCH_TEGRA_124_SOC
> > diff --git a/drivers/devfreq/Makefile b/drivers/devfreq/Makefile
> > index 32b8d4d..817dde7 100644
> > --- a/drivers/devfreq/Makefile
> > +++ b/drivers/devfreq/Makefile
> > @@ -9,6 +9,7 @@ obj-$(CONFIG_DEVFREQ_GOV_PASSIVE)	+= governor_passive.o
> >  
> >  # DEVFREQ Drivers
> >  obj-$(CONFIG_ARM_EXYNOS_BUS_DEVFREQ)	+= exynos-bus.o
> > +obj-$(CONFIG_ARM_MT8183_CCI_DEVFREQ)    += mt8183-cci-devfreq.o
> >  obj-$(CONFIG_ARM_RK3399_DMC_DEVFREQ)	+= rk3399_dmc.o
> >  obj-$(CONFIG_ARM_TEGRA_DEVFREQ)		+= tegra-devfreq.o
> >  
> > diff --git a/drivers/devfreq/mt8183-cci-devfreq.c b/drivers/devfreq/mt8183-cci-devfreq.c
> > new file mode 100644
> > index 0000000..af82d2e
> > --- /dev/null
> > +++ b/drivers/devfreq/mt8183-cci-devfreq.c
> > @@ -0,0 +1,235 @@
> > +// SPDX-License-Identifier: GPL-2.0
> > +/*
> > + * Copyright (c) 2019 MediaTek Inc.
> 
> You can add the author information under copyright information.
ok~
> 
> > + */
> > +
> > +#include <linux/clk.h>
> > +#include <linux/devfreq.h>
> > +#include <linux/module.h>
> > +#include <linux/of.h>
> > +#include <linux/platform_device.h>
> > +#include <linux/regulator/consumer.h>
> > +
> > +#include "governor.h"
> > +
> > +struct cci_devfreq {
> > +	struct devfreq		*devfreq;
> > +	struct regulator	*proc_reg;
> > +	unsigned long           proc_reg_uV;
> > +	struct clk		*cci_clk;
> > +	struct notifier_block	nb;
> 
> Just use the space instead of tab as following:
> 
> 	struct devfreq *devfreq;
> 	struct regulator *proc_reg;
> 	unsigned long proc_reg_uV;
> 	struct clk *cci_clk;
> 	struct notifier_block nb;
> 
OK, I will modify at next patch.
> > +};
> > +
> > +static int cci_devfreq_regulator_notifier(struct notifier_block *nb,
> > +					  unsigned long val, void *data)
> > +{
> > +	struct cci_devfreq *cci_df =
> > +		container_of(nb, struct cci_devfreq, nb);
> > +
> > +	/* deal with reduce frequency */
> > +	if (val & REGULATOR_EVENT_PRE_VOLTAGE_CHANGE) {
> > +		struct pre_voltage_change_data *pvc_data = data;
> > +
> > +		if (pvc_data->min_uV < pvc_data->old_uV) {
> > +			cci_df->proc_reg_uV =
> > +				(unsigned long)(pvc_data->min_uV);
> > +			mutex_lock(&cci_df->devfreq->lock);
> > +			update_devfreq(cci_df->devfreq);
> 
> Please handle the return value of update_devfreq() for exception handling.
OK, I will modify at next patch.
> 
> > +			mutex_unlock(&cci_df->devfreq->lock);
> > +		}
> > +	}
> > +
> > +	if ((val & REGULATOR_EVENT_ABORT_VOLTAGE_CHANGE) &&
> 
> if -> else if
> 
> At the same time, receives only one notification.
> It is not necessary to check the two if statement always, .
OK, I will modify at next patch.
> 
> 
> > +	    ((unsigned long)data > cci_df->proc_reg_uV)) {
> > +		cci_df->proc_reg_uV = (unsigned long)data;
> > +		mutex_lock(&cci_df->devfreq->lock);
> > +		update_devfreq(cci_df->devfreq);
> 
> ditto. Please check the return value of update_devfreq.
OK, I will modify at next patch.
> 
> > +		mutex_unlock(&cci_df->devfreq->lock);
> > +	}
> > +
> > +	/* deal with increase frequency */
> > +	if ((val & REGULATOR_EVENT_VOLTAGE_CHANGE) &&
> 
> ditto.
> if -> else if
> 
> At the same time, receives only one notification.
> It is not necessary to check the two if statement always, .
OK, I will modify at next patch.
> 
> 
> > +	    (cci_df->proc_reg_uV < (unsigned long)data)) {
> > +		cci_df->proc_reg_uV = (unsigned long)data;
> > +		mutex_lock(&cci_df->devfreq->lock);
> > +		update_devfreq(cci_df->devfreq);
> 
> ditto. Please check the return value of update_devfreq.
OK, I will modify at next patch.
> 
> > +		mutex_unlock(&cci_df->devfreq->lock);
> > +	}
> > +
> > +	return 0;
> > +}
> > +
> > +static int mtk_cci_governor_get_target(struct devfreq *devfreq,
> > +				       unsigned long *freq)
> > +{
> > +	struct cci_devfreq *cci_df;
> > +	struct dev_pm_opp *opp;
> > +
> > +	cci_df = dev_get_drvdata(devfreq->dev.parent);
> > +
> > +	/* find available frequency */
> > +	opp = dev_pm_opp_find_max_freq_by_volt(devfreq->dev.parent,
> > +						 cci_df->proc_reg_uV);
> > +	*freq = dev_pm_opp_get_freq(opp);
> > +
> > +	return 0;
> > +}
> > +
> > +static int mtk_cci_governor_event_handler(struct devfreq *devfreq,
> > +					  unsigned int event, void *data)
> > +{
> > +	struct cci_devfreq *cci_df;
> > +	struct notifier_block *nb;
> > +
> > +	cci_df = dev_get_drvdata(devfreq->dev.parent);
> > +	nb = &cci_df->nb;
> > +
> > +	switch (event) {
> > +	case DEVFREQ_GOV_START:
> > +	case DEVFREQ_GOV_RESUME:
> > +		nb->notifier_call = cci_devfreq_regulator_notifier;
> > +		regulator_register_notifier(cci_df->proc_reg,
> > +					    nb);
> 
> Please check the return value of regulator_register_notifier
> in order to handle the exception handling.
OK, I will modify at next patch.
> 
> 
> > +		break;
> > +
> > +	case DEVFREQ_GOV_STOP:
> > +	case DEVFREQ_GOV_SUSPEND:
> > +		regulator_unregister_notifier(cci_df->proc_reg,
> > +					    nb);
> 
> ditto.
> 
> > +
> 
> Remove unneeded blank line.
OK, I will modify at next patch.
> 
> > +		break;
> > +
> > +	default:
> > +		break;
> > +	}
> > +
> > +	return 0;
> > +}
> > +
> > +static struct devfreq_governor mtk_cci_devfreq_governor = {
> > +	.name = "mtk_cci_vmon",
> 
> How about editing the name from mtk_cci_vmon to mediatek_cci_voltage_monitor
> for the readability? Actually, 'mtk' and 'vmon' are not standard expression.
The srting of name is only [16], I'll leave it as mtk_cci_vmon.
> 
> > +	.get_target_freq = mtk_cci_governor_get_target,
> > +	.event_handler = mtk_cci_governor_event_handler,
> 
> Please add following code to make it as the immutable
> because the governor for this driver will not be changed
> through sysfs interface.
> 
> 	.immutable = true
OK, I will modify at next patch.
> 
> > +};
> > +
> > +static int mtk_cci_devfreq_target(struct device *dev, unsigned long *freq,
> > +				  u32 flags)
> > +{
> > +	struct cci_devfreq *cci_df = dev_get_drvdata(dev);
> > +
> > +	if (!cci_df)
> > +		return -EINVAL;
> > +
> > +	clk_set_rate(cci_df->cci_clk, *freq);
> 
> Please check the return value of clk_set_rate().
OK, I will modify at next patch.
> 
> > +
> > +	return 0;
> > +}
> > +
> > +static struct devfreq_dev_profile cci_devfreq_profile = {
> > +	.target		= mtk_cci_devfreq_target,
> 
> Just use the space instead of tab because cci_devfreq_profile
> only has one record.
> 
> 	.target = mtk_cci_devfreq_target,
OK, I will modify at next patch.
> 
> > +};
> > +
> > +static int mtk_cci_devfreq_probe(struct platform_device *pdev)
> > +{
> > +	struct device *cci_dev = &pdev->dev;
> > +	struct cci_devfreq *cci_df;
> > +	int ret;
> > +
> > +	cci_df = devm_kzalloc(cci_dev, sizeof(*cci_df), GFP_KERNEL);
> > +	if (!cci_df)
> > +		return -ENOMEM;
> > +
> > +	cci_df->cci_clk = clk_get(cci_dev, "cci_clock");
> 
> clk_get -> devm_clk_get()
OK, I will modify at next patch.
> 
> > +	ret = PTR_ERR_OR_ZERO(cci_df->cci_clk);
> > +	if (ret) {
> > +		if (ret != -EPROBE_DEFER)
> > +			dev_err(cci_dev, "failed to get clock for CCI: %d\n",
> > +				ret);
> > +
> 
> Remove unneeded blank line.
> 
> > +		return ret;
> > +	}> +
> > +	cci_df->proc_reg = regulator_get_optional(cci_dev, "proc");
> 
> 
> regulator_get_optional -> devm_regulator_get_optional
OK, I will modify at next patch.
> 
> > +	ret = PTR_ERR_OR_ZERO(cci_df->proc_reg);
> > +	if (ret) {
> > +		if (ret != -EPROBE_DEFER)
> > +			dev_err(cci_dev, "failed to get regulator for CCI: %d\n",
> > +				ret);
> > +
> 
> Remove unneeded blank line.
> 
> > +		goto err_put_clk;
> 
> If you use devm_clk_get(), just return instead of goto.
OK, I will rewrite these code.
> 
> > +	}
> > +
> > +	ret = dev_pm_opp_of_add_table(&pdev->dev);
> > +	if (ret) {
> > +		dev_err(cci_dev, "Fail to init CCI OPP table\n");
> > +		goto err_put_reg;
> > +	}
> > +
> > +	platform_set_drvdata(pdev, cci_df);
> > +
> > +	cci_df->devfreq = devm_devfreq_add_device(cci_dev,
> > +						       &cci_devfreq_profile,
> > +						       "mtk_cci_vmon",
> > +						       NULL);
> > +	if (IS_ERR(cci_df->devfreq)) {
> > +		dev_err(cci_dev, "cannot create cci devfreq device\n", ret);
> > +		goto err_put_reg;
> > +	}
> > +
> > +	return 0;
> > +
> > +err_put_reg:
> > +	regulator_put(cci_df->proc_reg);
> > +err_put_clk:
> > +	clk_put(cci_df->cci_clk);
> 
> If you use devm_clk_get()/devm_regulator_get(),
> 'err_put_reg' and 'err_put_clk' are unneeded.
OK, I will rewrite these code.
> 
> > +
> > +	return ret;
> > +}
> > +
> > +static const struct of_device_id mediatek_cci_devfreq_of_match[] = {
> > +	{ .compatible = "mediatek,mt8183-cci" },
> > +	{ },
> > +};
> > +MODULE_DEVICE_TABLE(of, mediatek_cci_devfreq_of_match);
> > +
> > +static struct platform_driver cci_devfreq_driver = {
> > +	.probe	= mtk_cci_devfreq_probe,
> > +	.driver = {
> > +		.name = "mediatek-cci-devfreq",
> > +		.of_match_table = mediatek_cci_devfreq_of_match,
> > +	},
> > +};
> > +
> > +static int __init mtk_cci_devfreq_init(void)
> > +{
> > +	int ret;
> > +
> > +	ret = devfreq_add_governor(&mtk_cci_devfreq_governor);
> > +	if (ret) {
> > +		pr_err("%s: failed to add governor: %d\n", __func__, ret);
> > +		return ret;
> > +	}
> > +
> > +	ret = platform_driver_register(&cci_devfreq_driver);
> > +	if (ret)
> > +		devfreq_remove_governor(&mtk_cci_devfreq_governor);
> > +
> > +	return ret;
> > +}
> > +module_init(mtk_cci_devfreq_init)
> > +
> > +static void __exit mtk_cci_devfreq_exit(void)
> > +{
> > +	int ret;
> > +
> > +	ret = devfreq_remove_governor(&mtk_cci_devfreq_governor);
> > +	if (ret)
> > +		pr_err("%s: failed to remove governor: %d\n", __func__, ret);
> > +
> > +	platform_driver_unregister(&cci_devfreq_driver);
> > +}
> > +module_exit(mtk_cci_devfreq_exit)
> > +
> > +MODULE_DESCRIPTION("Mediatek CCI devfreq driver");
> > +MODULE_AUTHOR("Andrew-sh.Cheng <andrew-sh.cheng@mediatek.com>");
> > +MODULE_LICENSE("GPL v2");
> > 
> 
> 



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