Re: [PATCH 2/3] devfreq: mediatek: add mt8183 cci devfreq driver

Jia-Wei Chang
2022-04-07T11:48:49Z

On Thu, 2022-04-07 at 12:20 +0900, Chanwoo Choi wrote:
> Hi,
>
> It seems that this patch depends on patches[1] of devfreq-testing
> branch.
> [1]
> https://urldefense.com/v3/__https://git.kernel.org/pub/scm/linux/kernel/git/chanwoo/linux.git/log/?h=devfreq-testing__;!!CTRNKA9wMg0ARbw!zpzMoFhloy2fpTawf8kkY5nwKerht5CKCnKTwwmSHYBN2vN5WfVMOcGn5TDb8SPTQTSaHA$
>
>
> I'll send the updated patches[1]. And I add the my comment below.
>

Yes, I will add your patches as my dependency.

>
> On 3/7/22 9:25 PM, Tim Chang wrote:
> > This adds a devfreq driver for the Cache Coherent Interconnect
> > (CCI) of
> > the Mediatek MT8183.
> >
> > On 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.
> >
> > Add need_voltage_tracking variable to platforma data. if true, it
> > indicates soc is required to realize the voltage tracking between
> > voltage of sram and voltage of cci by software approach. otherwise,
> > the
> > voltage tracking is realized by hardware appraoch.
> >
> > Add the notifier to cci so that it could react after svs driver
> > changes
> > opp table of cci.
> >
> > Signed-off-by: Jia-Wei Chang <
> > jia-wei.chang@mediatek.corp-partner.google.com>
> > ---
> > drivers/devfreq/Kconfig | 11 +-
> > drivers/devfreq/Makefile | 2 +-
> > drivers/devfreq/mtk-cci-devfreq.c | 471
> > ++++++++++++++++++++++++++++++
> > 3 files changed, 482 insertions(+), 2 deletions(-)
> > create mode 100644 drivers/devfreq/mtk-cci-devfreq.c
> >
> > diff --git a/drivers/devfreq/Kconfig b/drivers/devfreq/Kconfig
> > index 1ec36ae93f31..a6be3c6b5691 100644
> > --- a/drivers/devfreq/Kconfig
> > +++ b/drivers/devfreq/Kconfig
> > @@ -110,7 +110,7 @@ config ARM_IMX8M_DDRC_DEVFREQ
> >
> > config ARM_MT8183_CCI_DEVFREQ
> > tristate "MT8183 CCI DEVFREQ Driver"
> > - depends on ARM_MEDIATEK_CPUFREQ
> > + depends on OF && ARM_MEDIATEK_CPUFREQ
> > help
>
> ARM_MT8183_CCI_DEVFREQ is not existed on mainline kernel.
> You need to rework this patch on the latest kernel (either devfreq-
> next
> or linux-next.git).

Sure, I will rebase my patch onto linux-next.

>
> > This adds a devfreq driver for Cache Coherent
> > Interconnect
> > of Mediatek MT8183, which is shared the same regulator
> > @@ -130,6 +130,15 @@ config ARM_TEGRA_DEVFREQ
> > It reads ACTMON counters of memory controllers and adjusts
> > the
> > operating frequencies and voltages with OPP support.
> >
> > +config ARM_MEDIATEK_CCI_DEVFREQ
> > + tristate "MEDIATEK CCI DEVFREQ Driver"
> > + depends on OF && ARM_MEDIATEK_CPUFREQ
> > + help
> > + This adds a devfreq driver for Mediatek Cache Coherent
> > Interconnect
> > + 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_RK3399_DMC_DEVFREQ
> > tristate "ARM RK3399 DMC DEVFREQ Driver"
> > depends on (ARCH_ROCKCHIP && HAVE_ARM_SMCCC) || \
> > diff --git a/drivers/devfreq/Makefile b/drivers/devfreq/Makefile
> > index 991ef7740759..0493516a16f2 100644
> > --- a/drivers/devfreq/Makefile
> > +++ b/drivers/devfreq/Makefile
> > @@ -11,7 +11,7 @@ obj-$(CONFIG_DEVFREQ_GOV_PASSIVE) +=
> > governor_passive.o
> > obj-$(CONFIG_ARM_EXYNOS_BUS_DEVFREQ) += exynos-bus.o
> > obj-$(CONFIG_ARM_IMX_BUS_DEVFREQ) += imx-bus.o
> > obj-$(CONFIG_ARM_IMX8M_DDRC_DEVFREQ) += imx8m-ddrc.o
> > -obj-$(CONFIG_ARM_MT8183_CCI_DEVFREQ) += mt8183-cci-devfreq.o
> > +obj-$(CONFIG_ARM_MEDIATEK_CCI_DEVFREQ) += mtk-cci-devfreq.o
>
> As I commented, mt8183-cci-devfreq.c is not existed on latest kernel.

Yes, it will be fixed after rebasing onto linux-next.

>
> > obj-$(CONFIG_ARM_RK3399_DMC_DEVFREQ) += rk3399_dmc.o
> > obj-$(CONFIG_ARM_TEGRA_DEVFREQ) += tegra30-devfreq.o
> >
> > diff --git a/drivers/devfreq/mtk-cci-devfreq.c
> > b/drivers/devfreq/mtk-cci-devfreq.c
> > new file mode 100644
> > index 000000000000..986f34689f5c
> > --- /dev/null
> > +++ b/drivers/devfreq/mtk-cci-devfreq.c
> > @@ -0,0 +1,471 @@
> > +// SPDX-License-Identifier: GPL-2.0-only
> > +/*
> > + * Copyright (C) 2022 MediaTek Inc.
> > + */
> > +
> > +#include <linux/clk.h>
> > +#include <linux/devfreq.h>
> > +#include <linux/minmax.h>
> > +#include <linux/module.h>
> > +#include <linux/of.h>
> > +#include <linux/of_device.h>
> > +#include <linux/platform_device.h>
> > +#include <linux/pm_opp.h>
> > +#include <linux/regulator/consumer.h>
> > +
> > +struct mtk_ccifreq_platform_data;
>
> Instead of unneeded declaration,
> just define 'strcut mmk_ccifreq_platform_data' at here.

Yes, I will remove this forward declaration.

>
> > +
> > +struct mtk_ccifreq_drv {
> > + struct device *cci_dev;
> > + struct devfreq *devfreq;
> > + struct regulator *proc_reg;
> > + struct regulator *sram_reg;
> > + struct clk *cci_clk;
> > + struct clk *inter_clk;
> > + int inter_voltage;
> > + int old_voltage;
> > + unsigned long old_freq;
> > + struct mutex lock; /* avoid notify and policy race condition
> > */
> > + struct notifier_block opp_nb;
> > + const struct mtk_ccifreq_platform_data *soc_data;
> > +};
> > +
> > +struct mtk_ccifreq_platform_data {
> > + int min_volt_shift;
> > + int max_volt_shift;
> > + int proc_max_volt;
> > + int sram_min_volt;
> > + int sram_max_volt;
> > + bool need_voltage_tracking;
> > +};
>
> As I commented, move it before struct mtk_ccifreq_drv.

Yes, I will update it in the next version.

>
> > +
> > +static int mtk_ccifreq_voltage_tracking(struct mtk_ccifreq_drv
> > *drv, int new_voltage)
> > +{
> > + const struct mtk_ccifreq_platform_data *soc_data = drv-
> > >soc_data;
> > + struct regulator *proc_reg = drv->proc_reg;
> > + struct regulator *sram_reg = drv->sram_reg;
> > + int old_voltage, old_vsram, new_vsram, vsram, voltage, ret;
> > +
> > + old_voltage = regulator_get_voltage(proc_reg);
> > + if (old_voltage < 0) {
> > + pr_err("%s: invalid vproc value: %d\n", __func__,
> > old_voltage);
>
> Use dev_err instead of pr_err and don't use '__func__'.

Yes, I will fix it in the next version.

>
> > + return old_voltage;
> > + }
> > +
> > + old_vsram = regulator_get_voltage(sram_reg);
> > + if (old_vsram < 0) {
> > + pr_err("%s: invalid vsram value: %d\n", __func__,
> > old_vsram);
>
> ditto.

Yes, I will fix it in the next version.

>
> > + return old_vsram;
> > + }
> > +
> > + new_vsram = clamp(new_voltage + soc_data->min_volt_shift,
> > + soc_data->sram_min_volt, soc_data-
> > >sram_max_volt);
> > +
> > + do {
> > + if (old_voltage <= new_voltage) {
> > + vsram = clamp(old_voltage + soc_data-
> > >max_volt_shift,
> > + soc_data->sram_min_volt,
> > new_vsram);
> > + ret = regulator_set_voltage(sram_reg, vsram,
> > + soc_data-
> > >sram_max_volt);
> > + if (ret)
> > + return ret;
> > +
> > + if (vsram == soc_data->sram_max_volt ||
> > + new_vsram == soc_data->sram_min_volt)
> > + voltage = new_voltage;
> > + else
> > + voltage = vsram - soc_data-
> > >min_volt_shift;
> > +
> > + ret = regulator_set_voltage(proc_reg, voltage,
> > + soc_data-
> > >proc_max_volt);
> > + if (ret) {
> > + regulator_set_voltage(sram_reg,
> > old_vsram,
> > + soc_data-
> > >sram_max_volt);
> > + return ret;
> > + }
> > + } else if (old_voltage > new_voltage) {
> > + voltage = max(new_voltage,
> > + old_vsram - soc_data-
> > >max_volt_shift);
> > + ret = regulator_set_voltage(proc_reg, voltage,
> > + soc_data-
> > >proc_max_volt);
> > + if (ret)
> > + return ret;
> > +
> > + if (voltage == new_voltage)
> > + vsram = new_vsram;
> > + else
> > + vsram = max(new_vsram,
> > + voltage + soc_data-
> > >min_volt_shift);
> > +
> > + ret = regulator_set_voltage(sram_reg, vsram,
> > + soc_data-
> > >sram_max_volt);
> > + if (ret) {
> > + regulator_set_voltage(proc_reg,
> > old_voltage,
> > + soc_data-
> > >proc_max_volt);
> > + return ret;
> > + }
> > + }
> > +
> > + old_voltage = voltage;
> > + old_vsram = vsram;
> > + } while (voltage != new_voltage || vsram != new_vsram);
> > +
> > + return 0;
> > +}
> > +
> > +static int mtk_ccifreq_set_voltage(struct mtk_ccifreq_drv *drv,
> > int voltage)
> > +{
> > + int ret;
> > +
> > + if (drv->soc_data->need_voltage_tracking)
> > + ret = mtk_ccifreq_voltage_tracking(drv, voltage);
> > + else
> > + ret = regulator_set_voltage(drv->proc_reg, voltage,
> > + drv->soc_data-
> > >proc_max_volt);
> > +
> > + if (!ret)
> > + drv->old_voltage = voltage;
> > +
> > + return ret;
> > +}
> > +
> > +static int mtk_ccifreq_target(struct device *dev, unsigned long
> > *freq,
> > + u32 flags)
> > +{
>
> I recommend that you handle the error case by using 'goto' statement
> instead of handling them in each error case. You can refer the
> other devfreq device driver for handling error case with goto.

Sure, I will refactor it with 'goto' statement in the next version.

>
> > + struct mtk_ccifreq_drv *drv = dev_get_drvdata(dev);
> > + struct clk *cci_pll = clk_get_parent(drv->cci_clk);
> > + struct dev_pm_opp *opp;
> > + unsigned long opp_rate;
> > + int voltage, old_voltage, inter_voltage, target_voltage, ret;
> > +
> > + if (!drv)
> > + return -EINVAL;
> > +
> > + if (drv->old_freq == *freq)
> > + return 0;
> > +
> > + inter_voltage = drv->inter_voltage;
> > +
> > + opp_rate = *freq;
> > + opp = devfreq_recommended_opp(dev, &opp_rate, 1);
> > + if (IS_ERR(opp)) {
> > + pr_err("cci: failed to find opp for freq: %ld\n",
> > opp_rate);
>
> ditto.

Ok, I will use 'goto' to handle error.

>
> > + return PTR_ERR(opp);
> > + }
> > + voltage = dev_pm_opp_get_voltage(opp);
> > + dev_pm_opp_put(opp);
> > +
> > + old_voltage = drv->old_voltage;
> > + if (old_voltage == 0)
> > + old_voltage = regulator_get_voltage(drv->proc_reg);
> > + if (old_voltage < 0) {
> > + pr_err("cci: invalid vproc value: %d\n", old_voltage);
>
> ditto. Use dev_err instead of pr_err.

Ok, I will use dev_err instread.

>
> > + return old_voltage;
> > + }
> > +
> > + mutex_lock(&drv->lock);
> > +
> > + /* scale up: set voltage first then freq. */
> > + target_voltage = max(inter_voltage, voltage);
> > + if (old_voltage <= target_voltage) {
> > + ret = mtk_ccifreq_set_voltage(drv, target_voltage);
> > + if (ret) {
> > + pr_err("cci: failed to scale up voltage\n");
>
> ditto.

Ok, I will use dev_err instread.

>
> > + mtk_ccifreq_set_voltage(drv, old_voltage);
> > + mutex_unlock(&drv->lock);
> > + return ret;
> > + }
> > + }
> > +
> > + /* switch the cci clock to intermediate clock source. */
> > + ret = clk_set_parent(drv->cci_clk, drv->inter_clk);
> > + if (ret) {
> > + pr_err("cci: failed to re-parent cci clock\n");
>
> ditto.

Ok, I will use dev_err instread.

>
> > + mtk_ccifreq_set_voltage(drv, old_voltage);
> > + WARN_ON(1);
>
> I think that it is not necessary. Please remove it.

Yes, I will remove it.

>
> > + mutex_unlock(&drv->lock);
> > + return ret;
> > + }
> > +
> > + /* set the original clock to target rate. */
> > + ret = clk_set_rate(cci_pll, *freq);
> > + if (ret) {
> > + pr_err("cci: failed to set cci pll rate: %d\n", ret);
>
> ditto.

Ok, I will use dev_err instread.

>
> > + clk_set_parent(drv->cci_clk, cci_pll);
> > + mtk_ccifreq_set_voltage(drv, old_voltage);
> > + mutex_unlock(&drv->lock);
> > + return ret;
> > + }
> > +
> > + /* switch the cci clock back to the original clock source. */
> > + ret = clk_set_parent(drv->cci_clk, cci_pll);
> > + if (ret) {
> > + pr_err("cci: failed to re-parent cci clock\n");
>
> ditto.

Ok, I will use dev_err instread.

>
> > + mtk_ccifreq_set_voltage(drv, inter_voltage);
> > + WARN_ON(1);
>
> ditto.

Ok, I will remove it.

>
> > + mutex_unlock(&drv->lock);
> > + return ret;
> > + }
> > +
> > + /*
> > + * If the new voltage is lower than the intermediate voltage or
> > the
> > + * original voltage, scale down to the new voltage.
> > + */
> > + if (voltage < inter_voltage || voltage < old_voltage) {
> > + ret = mtk_ccifreq_set_voltage(drv, voltage);
> > + if (ret) {
> > + pr_err("cci: failed to scale down voltage\n");
>
> ditto.

Ok, I will use dev_err instread.

>
> > + WARN_ON(1);
>
> ditto.

Ok, I will remove it.

>
> > + mutex_unlock(&drv->lock);
> > + return ret;
> > + }
> > + }
> > +
> > + drv->old_freq = *freq;
> > + mutex_unlock(&drv->lock);
> > +
> > + return 0;
> > +}
> > +
> > +static int mtk_ccifreq_opp_notifier(struct notifier_block *nb,
> > + unsigned long event, void *data)
> > +{
> > + struct dev_pm_opp *opp = data;
> > + struct mtk_ccifreq_drv *drv;
> > + unsigned long freq, volt;
> > +
> > + drv = container_of(nb, struct mtk_ccifreq_drv, opp_nb);
> > +
> > + if (event == OPP_EVENT_ADJUST_VOLTAGE) {
> > + freq = dev_pm_opp_get_freq(opp);
> > +
> > + mutex_lock(&drv->lock);
> > + /* current opp item is changed */
> > + if (freq == drv->old_freq) {
> > + volt = dev_pm_opp_get_voltage(opp);
> > + mtk_ccifreq_set_voltage(drv, volt);
> > + }
> > + mutex_unlock(&drv->lock);
> > + }
> > +
> > + return 0;
> > +}
> > +
> > +static struct devfreq_dev_profile mtk_ccifreq_profile = {
> > + .target = mtk_ccifreq_target,
> > +};
> > +
> > +static int mtk_ccifreq_probe(struct platform_device *pdev)
> > +{
> > + struct device *cci_dev = &pdev->dev;
> > + struct mtk_ccifreq_drv *drv;
> > + struct devfreq_passive_data *passive_data;
> > + struct dev_pm_opp *opp;
> > + unsigned long rate, opp_volt;
> > + int ret;
> > +
> > + drv = devm_kzalloc(cci_dev, sizeof(*drv), GFP_KERNEL);
> > + if (!drv)
> > + return -ENOMEM;
> > +
> > + drv->cci_dev = cci_dev;
> > + drv->soc_data = (const struct mtk_ccifreq_platform_data *)
> > + of_device_get_match_data(&pdev->dev);
> > + mutex_init(&drv->lock);
> > + platform_set_drvdata(pdev, drv);
> > +
> > + drv->cci_clk = devm_clk_get(cci_dev, "cci");
> > + if (IS_ERR(drv->cci_clk)) {
> > + ret = PTR_ERR(drv->cci_clk);
> > + return dev_err_probe(cci_dev, ret,
> > + "cci: failed to get cci clk:
> > %d\n",
> > + ret);
> > + }
> > +
> > + drv->inter_clk = devm_clk_get(cci_dev, "intermediate");
> > + if (IS_ERR(drv->inter_clk)) {
> > + ret = PTR_ERR(drv->inter_clk);
> > + return dev_err_probe(cci_dev, ret,
> > + "cci: failed to get intermediate
> > clk: %d\n",
> > + ret);
> > + }
> > +
> > + if (drv->soc_data->need_voltage_tracking) {
> > + drv->sram_reg = regulator_get_optional(cci_dev,
> > "sram");
> > + if (IS_ERR_OR_NULL(drv->sram_reg)) {
> > + ret = PTR_ERR(drv->sram_reg);
> > + return dev_err_probe(cci_dev, ret,
> > + "cci: failed to get sram
> > regulator: %d\n",
> > + ret);
> > + }
> > +
> > + ret = regulator_enable(drv->sram_reg);
> > + if (ret) {
> > + dev_warn(cci_dev,
> > + "cci: failed to enable sram
> > regulator\n");
>
> If you want to break the probe sequence, better to use 'dev_err'
> instead of 'dev_warn' if there is no any reason to use dev_warn.
>

Ok, I will use dev_err.

>
> > + return ret;
> > + }
> > + }
> > +
> > + drv->proc_reg = devm_regulator_get_optional(cci_dev, "proc");
> > + if (IS_ERR(drv->proc_reg)) {
> > + ret = PTR_ERR(drv->proc_reg);
> > + dev_err_probe(cci_dev, ret,
> > + "cci: failed to get proc regulator:
> > %d\n",
> > + ret);
> > + goto out_disable_sram_reg;
> > + }
> > +
> > + ret = regulator_enable(drv->proc_reg);
> > + if (ret) {
> > + dev_warn(cci_dev, "cci: failed to enable proc
> > regulator\n");
>
> ditto. Use dev_err.

Ok, I will replace all dev_warn with dev_err in the patch.

>
> > + goto out_disable_sram_reg;
> > + }
> > +
> > + ret = clk_prepare_enable(drv->cci_clk);
> > + if (ret)
> > + goto out_disable_proc_reg;
> > +
> > + ret = clk_prepare_enable(drv->inter_clk);
> > + if (ret)
> > + goto out_disable_cci_clk;
> > +
> > + ret = dev_pm_opp_of_add_table(cci_dev);
> > + if (ret) {
> > + dev_warn(cci_dev, "cci: failed to add opp table: %d\n",
> > ret);
> > + goto out_disable_inter_clk;
> > + }
> > +
> > + rate = clk_get_rate(drv->inter_clk);
> > + opp = dev_pm_opp_find_freq_ceil(cci_dev, &rate);
> > + if (IS_ERR(opp)) {
> > + ret = PTR_ERR(opp);
> > + dev_err(cci_dev, "cci: failed to get intermediate opp:
> > %d\n",
> > + ret);
> > + goto out_remove_opp_table;
> > + }
> > + drv->inter_voltage = dev_pm_opp_get_voltage(opp);
> > + dev_pm_opp_put(opp);
> > +
> > + rate = U32_MAX;
> > + opp = dev_pm_opp_find_freq_floor(drv->cci_dev, &rate);
> > + if (IS_ERR(opp)) {
> > + pr_err("failed to get opp\n");
> > + ret = PTR_ERR(opp);
> > + goto out_remove_opp_table;
> > + }
> > +
> > + opp_volt = dev_pm_opp_get_voltage(opp);
> > + dev_pm_opp_put(opp);
> > + ret = mtk_ccifreq_set_voltage(drv, opp_volt);
> > + if (ret) {
> > + pr_err("failed to scale to highest voltage %lu in
> > proc_reg\n",
> > + opp_volt);
>
> Use dev_err.

Ok, I will use dev_err instread.

>
> > + goto out_remove_opp_table;
> > + }
> > +
> > + passive_data = devm_kzalloc(cci_dev, sizeof(struct
> > devfreq_passive_data), GFP_KERNEL);
> > + if (!passive_data) {
> > + ret = -ENOMEM;
> > + goto out_remove_opp_table;
> > + }
> > +
> > + passive_data->parent_type = CPUFREQ_PARENT_DEV;
>
> It seems that depend on patchset[1]. I'll send the updated patch
> within one week.
> [1]
> https://urldefense.com/v3/__https://git.kernel.org/pub/scm/linux/kernel/git/chanwoo/linux.git/log/?h=devfreq-testing__;!!CTRNKA9wMg0ARbw!zpzMoFhloy2fpTawf8kkY5nwKerht5CKCnKTwwmSHYBN2vN5WfVMOcGn5TDb8SPTQTSaHA$
>

Should I send my patch after yours? Or the order makes no difference?

>
> > + drv->devfreq = devm_devfreq_add_device(cci_dev,
> > + &mtk_ccifreq_profile,
> > + DEVFREQ_GOV_PASSIVE,
> > + passive_data);
> > + if (IS_ERR(drv->devfreq)) {
> > + ret = -EPROBE_DEFER;
> > + dev_err(cci_dev, "cci: failed to add devfreq device:
> > %d\n",
> > + PTR_ERR(drv->devfreq));
> > + goto out_remove_opp_table;
> > + }
> > +
> > + drv->opp_nb.notifier_call = mtk_ccifreq_opp_notifier;
> > + ret = dev_pm_opp_register_notifier(cci_dev, &drv->opp_nb);
> > + if (ret) {
> > + dev_warn(cci_dev, "cci: failed to register opp
> > notifier: %d\n",
> > + ret);
> > + goto out_remove_devfreq_device;
> > + }
> > +
> > + return 0;
> > +
> > +out_remove_devfreq_device:
> > + devm_devfreq_remove_device(cci_dev, drv->devfreq);
> > +
> > +out_remove_opp_table:
> > + dev_pm_opp_of_remove_table(cci_dev);
> > +
> > +out_disable_inter_clk:
> > + clk_disable_unprepare(drv->inter_clk);
> > +
> > +out_disable_cci_clk:
> > + clk_disable_unprepare(drv->cci_clk);
> > +
> > +out_disable_proc_reg:
> > + regulator_disable(drv->proc_reg);
> > +
> > +out_disable_sram_reg:
> > + if (drv->soc_data->need_voltage_tracking)
> > + regulator_disable(drv->sram_reg);
> > +
> > + return ret;
> > +}
> > +
> > +static int mtk_ccifreq_remove(struct platform_device *pdev)
> > +{
> > + struct device *cci_dev = &pdev->dev;
> > + struct mtk_ccifreq_drv *drv;
> > +
> > + drv = platform_get_drvdata(pdev);
> > +
> > + dev_pm_opp_unregister_notifier(cci_dev, &drv->opp_nb);
> > + dev_pm_opp_of_remove_table(cci_dev);
> > + regulator_disable(drv->proc_reg);
> > + if (!IS_ERR(drv->sram_reg))
> > + regulator_disable(drv->sram_reg);
> > +
> > + return 0;
> > +}
> > +
> > +static const struct mtk_ccifreq_platform_data mtk_platform_data =
> > {
> > + .min_volt_shift = 0,
> > + .max_volt_shift = 0,
> > + .proc_max_volt = 1150000,
> > + .sram_min_volt = 0,
> > + .sram_max_volt = 0,
> > + .need_voltage_tracking = false,
> > +};
> > +
> > +static const struct of_device_id mtk_ccifreq_machines[] = {
> > + { .compatible = "mediatek,mt8183-cci", .data =
> > &mtk_platform_data },
> > + { },
> > +};
> > +MODULE_DEVICE_TABLE(of, mtk_ccifreq_machines);
> > +
> > +static struct platform_driver mtk_ccifreq_platdrv = {
> > + .probe = mtk_ccifreq_probe,
> > + .remove = mtk_ccifreq_remove,
> > + .driver = {
> > + .name = "mtk-ccifreq",
> > + .of_match_table = of_match_ptr(mtk_ccifreq_machines),
> > + },
> > +};
> > +
> > +static int __init mtk_ccifreq_platdrv_init(void)
> > +{
> > + return platform_driver_register(&mtk_ccifreq_platdrv);
> > +}
> > +module_init(mtk_ccifreq_platdrv_init)
> > +
> > +static void __exit mtk_ccifreq_platdrv_exit(void)
> > +{
> > + platform_driver_unregister(&mtk_ccifreq_platdrv);
> > +}
> > +module_exit(mtk_ccifreq_platdrv_exit)
> > +
> > +MODULE_DESCRIPTION("Mediatek CCI devfreq driver");
> > +MODULE_AUTHOR("Jia-Wei Chang <jia-wei.chang@mediatek.com>");
> > +MODULE_LICENSE("GPL v2");
> >