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Message-ID: <20190408172220.GA28972@roeck-us.net>
Date: Mon, 8 Apr 2019 10:22:21 -0700
From: Guenter Roeck <linux@...ck-us.net>
To: Andrew-sh Cheng <andrew-sh.cheng@...iatek.com>
Cc: MyungJoo Ham <myungjoo.ham@...sung.com>,
Kyungmin Park <kyungmin.park@...sung.com>,
Chanwoo Choi <cw00.choi@...sung.com>,
Rob Herring <robh+dt@...nel.org>,
Mark Rutland <mark.rutland@....com>,
Matthias Brugger <matthias.bgg@...il.com>,
"Rafael J. Wysocki" <rjw@...ysocki.net>,
Viresh Kumar <viresh.kumar@...aro.org>,
devicetree@...r.kernel.org, srv_heupstream@...iatek.com,
linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org,
fan.chen@...iatek.com, linux-mediatek@...ts.infradead.org,
linux-arm-kernel@...ts.infradead.org
Subject: Re: [v2,4/4] devfreq: add mediatek cci devfreq
On Fri, Mar 29, 2019 at 02:46:12PM +0800, 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@...iatek.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.
> + */
> +
> +#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;
> +};
> +
> +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);
> + mutex_unlock(&cci_df->devfreq->lock);
> + }
> + }
> +
> + if ((val & REGULATOR_EVENT_ABORT_VOLTAGE_CHANGE) &&
> + ((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);
> + mutex_unlock(&cci_df->devfreq->lock);
> + }
> +
> + /* deal with increase frequency */
> + if ((val & REGULATOR_EVENT_VOLTAGE_CHANGE) &&
> + (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);
> + 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);
> + break;
> +
> + case DEVFREQ_GOV_STOP:
> + case DEVFREQ_GOV_SUSPEND:
> + regulator_unregister_notifier(cci_df->proc_reg,
> + nb);
> +
> + break;
> +
> + default:
> + break;
> + }
> +
> + return 0;
> +}
> +
> +static struct devfreq_governor mtk_cci_devfreq_governor = {
> + .name = "mtk_cci_vmon",
> + .get_target_freq = mtk_cci_governor_get_target,
> + .event_handler = mtk_cci_governor_event_handler,
> +};
> +
> +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);
> +
> + return 0;
> +}
> +
> +static struct devfreq_dev_profile cci_devfreq_profile = {
> + .target = mtk_cci_devfreq_target,
> +};
> +
> +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");
Should use devm_clk_get().
> + 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);
> +
> + return ret;
> + }
> +
> + cci_df->proc_reg = regulator_get_optional(cci_dev, "proc");
Should use devm_regulator_get_optional().
> + 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);
> +
> + goto err_put_clk;
> + }
> +
> + ret = dev_pm_opp_of_add_table(&pdev->dev);
> + if (ret) {
> + dev_err(cci_dev, "Fail to init CCI OPP table\n");
No error code display here ? Not that it really matters, but it is
inconsistent with the other error messages.
> + 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)) {
ret = PTR_ERR(cci_df->devfreq);
> + dev_err(cci_dev, "cannot create cci devfreq device\n", ret);
dev_err(cci_dev, "cannot create cci devfreq device: %d\n", ret);
Something like
dev_pm_opp_of_remove_table(...);
seems to be missing here.
> + goto err_put_reg;
> + }
> +
> + return 0;
> +
> +err_put_reg:
> + regulator_put(cci_df->proc_reg);
> +err_put_clk:
> + clk_put(cci_df->cci_clk);
Can be dropped when using devm_ functions above.
> +
> + 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,
If the driver depends on OF, that should be stated in the Kconfig file.
Otherwise, of_match_ptr() should be used, and mediatek_cci_devfreq_of_match
should be tagged with __maybe_unused (or made conditional with #ifdef).
> + },
> +};
> +
> +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@...iatek.com>");
> +MODULE_LICENSE("GPL v2");
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