[PATCH v5 2/2] PM / devfreq: mediatek: Introduce MediaTek CCI devfreq driver
Johnson Wang
johnson.wang at mediatek.com
Wed May 25 05:09:19 PDT 2022
On Fri, 2022-05-20 at 15:46 +0200, Christophe JAILLET wrote:
> Hi,
>
> Should there be a v6, below a few nitpicks.
>
> just my 2c.
>
> CJ
>
> Le 20/05/2022 à 15:19, Johnson Wang a écrit :
> > We introduce a devfreq driver for the MediaTek Cache Coherent
> > Interconnect
> > (CCI) used by some MediaTek SoCs.
> >
> > In this driver, we use the passive devfreq driver to get target
> > frequencies
> > and adjust voltages accordingly. In MT8183 and MT8186, the MediaTek
> > CCI
> > is supplied by the same regulators with the little core CPUs.
> >
> > Signed-off-by: Jia-Wei Chang <
> > jia-wei.chang-NuS5LvNUpcJWk0Htik3J/w at public.gmane.org>
> > Signed-off-by: Johnson Wang <
> > johnson.wang-NuS5LvNUpcJWk0Htik3J/w at public.gmane.org>
> > Acked-by: Chanwoo Choi <
> > cw00.choi-Sze3O3UU22JBDgjK7y7TUQ at public.gmane.org>
> > ---
> > This patch depends on "devfreq-testing"[1].
> > [1]
> > https://urldefense.com/v3/__https://git.kernel.org/pub/scm/linux/kernel/git/chanwoo/linux.git/log/?h=devfreq-testing__;!!CTRNKA9wMg0ARbw!2b72S6ItcAh5WYWrdSYl8RdvSZnPx_oWPF2agvZ3GtKWNthEgFhpXT_RCScRUxeMMuxK$
> >
> > ---
> > drivers/devfreq/Kconfig | 10 +
> > drivers/devfreq/Makefile | 1 +
> > drivers/devfreq/mtk-cci-devfreq.c | 447
> > ++++++++++++++++++++++++++++++
> > 3 files changed, 458 insertions(+)
> > create mode 100644 drivers/devfreq/mtk-cci-devfreq.c
> >
> > diff --git a/drivers/devfreq/Kconfig b/drivers/devfreq/Kconfig
> > index 87eb2b837e68..9754d8b31621 100644
> > --- a/drivers/devfreq/Kconfig
> > +++ b/drivers/devfreq/Kconfig
> > @@ -120,6 +120,16 @@ 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 ARM_MEDIATEK_CPUFREQ || COMPILE_TEST
> > + select DEVFREQ_GOV_PASSIVE
> > + help
> > + This adds a devfreq driver for MediaTek Cache Coherent
> > Interconnect
> > + which is shared the same regulators with the cpu cluster. It
> > can track
> > + buck voltages and update a proper CCI frequency. Use the
> > notification
> > + to get the 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 0b6be92a25d9..bf40d04928d0 100644
> > --- a/drivers/devfreq/Makefile
> > +++ b/drivers/devfreq/Makefile
> > @@ -11,6 +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-$(CONFIG_ARM_MEDIATEK_CCI_DEVFREQ) += mtk-cci-devfreq.o
> > obj-$(CONFIG_ARM_RK3399_DMC_DEVFREQ) += rk3399_dmc.o
> > obj-$(CONFIG_ARM_SUN8I_A33_MBUS_DEVFREQ) += sun8i-a33-mbus.o
> > obj-$(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..2eaff24fb487
> > --- /dev/null
> > +++ b/drivers/devfreq/mtk-cci-devfreq.c
> > @@ -0,0 +1,447 @@
> > +// 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 {
> > + int min_volt_shift;
> > + int max_volt_shift;
> > + int proc_max_volt;
> > + int sram_min_volt;
> > + int sram_max_volt;
> > +};
> > +
> > +struct mtk_ccifreq_drv {
> > + struct device *dev;
> > + struct devfreq *devfreq;
> > + struct regulator *proc_reg;
> > + struct regulator *sram_reg;
> > + struct clk *cci_clk;
> > + struct clk *inter_clk;
> > + int inter_voltage;
> > + unsigned long pre_freq;
> > + /* Avoid race condition for regulators between notify and
> > policy */
> > + struct mutex reg_lock;
> > + struct notifier_block opp_nb;
> > + const struct mtk_ccifreq_platform_data *soc_data;
> > + int vtrack_max;
> > +};
> > +
> > +static int mtk_ccifreq_set_voltage(struct mtk_ccifreq_drv *drv,
> > int new_voltage)
> > +{
> > + const struct mtk_ccifreq_platform_data *soc_data = drv-
> > >soc_data;
> > + struct device *dev = drv->dev;
> > + int pre_voltage, pre_vsram, new_vsram, vsram, voltage, ret;
> > + int retry_max = drv->vtrack_max;
> > +
> > + if (!drv->sram_reg) {
> > + ret = regulator_set_voltage(drv->proc_reg, new_voltage,
> > + drv->soc_data-
> > >proc_max_volt);
> > + return ret;
> > + }
> > +
> > + pre_voltage = regulator_get_voltage(drv->proc_reg);
> > + if (pre_voltage < 0) {
> > + dev_err(dev, "invalid vproc value: %d\n", pre_voltage);
> > + return pre_voltage;
> > + }
> > +
> > + pre_vsram = regulator_get_voltage(drv->sram_reg);
> > + if (pre_vsram < 0) {
> > + dev_err(dev, "invalid vsram value: %d\n", pre_vsram);
> > + return pre_vsram;
> > + }
> > +
> > + new_vsram = clamp(new_voltage + soc_data->min_volt_shift,
> > + soc_data->sram_min_volt, soc_data-
> > >sram_max_volt);
> > +
> > + do {
> > + if (pre_voltage <= new_voltage) {
> > + vsram = clamp(pre_voltage + soc_data-
> > >max_volt_shift,
> > + soc_data->sram_min_volt,
> > new_vsram);
> > + ret = regulator_set_voltage(drv->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(drv->proc_reg,
> > voltage,
> > + soc_data-
> > >proc_max_volt);
> > + if (ret) {
> > + regulator_set_voltage(drv->sram_reg,
> > pre_vsram,
> > + soc_data-
> > >sram_max_volt);
> > + return ret;
> > + }
> > + } else if (pre_voltage > new_voltage) {
> > + voltage = max(new_voltage,
> > + pre_vsram - soc_data-
> > >max_volt_shift);
> > + ret = regulator_set_voltage(drv->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(drv->sram_reg,
> > vsram,
> > + soc_data-
> > >sram_max_volt);
> > + if (ret) {
> > + regulator_set_voltage(drv->proc_reg,
> > pre_voltage,
> > + soc_data-
> > >proc_max_volt);
> > + return ret;
> > + }
> > + }
> > +
> > + pre_voltage = voltage;
> > + pre_vsram = vsram;
> > +
> > + if (--retry_max < 0) {
> > + dev_err(dev,
> > + "over loop count, failed to set
> > voltage\n");
> > + return -EINVAL;
> > + }
> > + } while (voltage != new_voltage || vsram != new_vsram);
> > +
> > + return ret;
>
> 'return 0;' would be more explicit. (it looks like 'ret' is always 0
> if
> we arrive here)
>
>
> > +}
> > +
> > +static int mtk_ccifreq_target(struct device *dev, unsigned long
> > *freq,
> > + u32 flags)
> > +{
> > + 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, pre_voltage, inter_voltage, target_voltage, ret;
> > +
> > + if (!drv)
> > + return -EINVAL;
> > +
> > + if (drv->pre_freq == *freq)
> > + return 0;
> > +
> > + inter_voltage = drv->inter_voltage;
> > +
> > + opp_rate = *freq;
> > + opp = devfreq_recommended_opp(dev, &opp_rate, 1);
> > + if (IS_ERR(opp)) {
> > + dev_err(dev, "failed to find opp for freq: %ld\n",
> > opp_rate);
> > + return PTR_ERR(opp);
> > + }
> > +
> > + mutex_lock(&drv->reg_lock);
> > +
> > + voltage = dev_pm_opp_get_voltage(opp);
> > + dev_pm_opp_put(opp);
> > +
> > + pre_voltage = regulator_get_voltage(drv->proc_reg);
> > + if (pre_voltage < 0) {
> > + dev_err(dev, "invalid vproc value: %d\n", pre_voltage);
> > + ret = pre_voltage;
> > + goto out_unlock;
> > + }
> > +
> > + /* scale up: set voltage first then freq. */
> > + target_voltage = max(inter_voltage, voltage);
> > + if (pre_voltage <= target_voltage) {
> > + ret = mtk_ccifreq_set_voltage(drv, target_voltage);
> > + if (ret) {
> > + dev_err(dev, "failed to scale up voltage\n");
> > + goto out_restore_voltage;
> > + }
> > + }
> > +
> > + /* switch the cci clock to intermediate clock source. */
> > + ret = clk_set_parent(drv->cci_clk, drv->inter_clk);
> > + if (ret) {
> > + dev_err(dev, "failed to re-parent cci clock\n");
> > + goto out_restore_voltage;
> > + }
> > +
> > + /* set the original clock to target rate. */
> > + ret = clk_set_rate(cci_pll, *freq);
> > + if (ret) {
> > + dev_err(dev, "failed to set cci pll rate: %d\n", ret);
> > + clk_set_parent(drv->cci_clk, cci_pll);
> > + goto out_restore_voltage;
> > + }
> > +
> > + /* switch the cci clock back to the original clock source. */
> > + ret = clk_set_parent(drv->cci_clk, cci_pll);
> > + if (ret) {
> > + dev_err(dev, "failed to re-parent cci clock\n");
> > + mtk_ccifreq_set_voltage(drv, inter_voltage);
> > + goto out_unlock;
> > + }
> > +
> > + /*
> > + * 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 < pre_voltage) {
> > + ret = mtk_ccifreq_set_voltage(drv, voltage);
> > + if (ret) {
> > + dev_err(dev, "failed to scale down voltage\n");
> > + goto out_unlock;
> > + }
> > + }
> > +
> > + drv->pre_freq = *freq;
> > + mutex_unlock(&drv->reg_lock);
> > +
> > + return 0;
> > +
> > +out_restore_voltage:
> > + mtk_ccifreq_set_voltage(drv, pre_voltage);
> > +
> > +out_unlock:
> > + mutex_unlock(&drv->reg_lock);
> > + return ret;
> > +}
> > +
> > +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->reg_lock);
> > + /* current opp item is changed */
> > + if (freq == drv->pre_freq) {
> > + volt = dev_pm_opp_get_voltage(opp);
> > + mtk_ccifreq_set_voltage(drv, volt);
> > + }
> > + mutex_unlock(&drv->reg_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 *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(dev, sizeof(*drv), GFP_KERNEL);
> > + if (!drv)
> > + return -ENOMEM;
> > +
> > + drv->dev = dev;
> > + drv->soc_data = (const struct mtk_ccifreq_platform_data *)
> > + of_device_get_match_data(&pdev->dev);
> > + mutex_init(&drv->reg_lock);
> > + platform_set_drvdata(pdev, drv);
> > +
> > + drv->cci_clk = devm_clk_get(dev, "cci");
> > + if (IS_ERR(drv->cci_clk)) {
> > + ret = PTR_ERR(drv->cci_clk);
> > + return dev_err_probe(dev, ret,
> > + "failed to get cci clk: %d\n",
> > ret);
> > + }
> > +
> > + drv->inter_clk = devm_clk_get(dev, "intermediate");
> > + if (IS_ERR(drv->inter_clk)) {
> > + ret = PTR_ERR(drv->inter_clk);
> > + dev_err_probe(dev, ret,
> > + "failed to get intermediate clk: %d\n",
> > ret);
> > + goto out_free_resources;
>
> Could be a direct return, nothing to undo in the error handling path.
>
> > + }
> > +
> > + drv->proc_reg = devm_regulator_get_optional(dev, "proc");
> > + if (IS_ERR(drv->proc_reg)) {
> > + ret = PTR_ERR(drv->proc_reg);
> > + dev_err_probe(dev, ret,
> > + "failed to get proc regulator: %d\n",
> > ret);
> > + goto out_free_resources;
>
> Could be a direct return, nothing to undo in the error handling path.
>
> > + }
> > +
> > + ret = regulator_enable(drv->proc_reg);
> > + if (ret) {
> > + dev_err(dev, "failed to enable proc regulator\n");
> > + goto out_free_resources;
>
> Could be a direct return, nothing to undo in the error handling path.
>
> > + }
> > +
> > + drv->sram_reg = devm_regulator_get_optional(dev, "sram");
> > + if (IS_ERR(drv->sram_reg))
> > + drv->sram_reg = NULL;
> > + else {
> > + ret = regulator_enable(drv->sram_reg);
> > + if (ret) {
> > + dev_err(dev, "failed to enable sram
> > regulator\n");
> > + goto out_free_resources;
> > + }
> > + }
> > +
> > + /*
> > + * We assume min voltage is 0 and tracking target voltage using
> > + * min_volt_shift for each iteration.
> > + * The retry_max is 3 times of expected iteration count.
> > + */
> > + drv->vtrack_max = 3 * DIV_ROUND_UP(max(drv->soc_data-
> > >sram_max_volt,
> > + drv->soc_data-
> > >proc_max_volt),
> > + drv->soc_data-
> > >min_volt_shift);
> > +
> > + ret = clk_prepare_enable(drv->cci_clk);
> > + if (ret)
> > + goto out_free_resources;
> > +
> > + ret = dev_pm_opp_of_add_table(dev);
> > + if (ret) {
> > + dev_err(dev, "failed to add opp table: %d\n", ret);
> > + goto out_disable_cci_clk;
> > + }
> > +
> > + rate = clk_get_rate(drv->inter_clk);
> > + opp = dev_pm_opp_find_freq_ceil(dev, &rate);
> > + if (IS_ERR(opp)) {
> > + ret = PTR_ERR(opp);
> > + dev_err(dev, "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->dev, &rate);
> > + if (IS_ERR(opp)) {
> > + dev_err(dev, "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) {
> > + dev_err(dev, "failed to scale to highest voltage %lu in
> > proc_reg\n",
> > + opp_volt);
> > + goto out_remove_opp_table;
> > + }
> > +
> > + passive_data = devm_kzalloc(dev, sizeof(struct
> > devfreq_passive_data),
> > + GFP_KERNEL);
>
> sizeof(*passive_data) could maybe save 1 LoC.
>
> > + if (!passive_data) {
> > + ret = -ENOMEM;
> > + goto out_remove_opp_table;
> > + }
> > +
> > + passive_data->parent_type = CPUFREQ_PARENT_DEV;
> > + drv->devfreq = devm_devfreq_add_device(dev,
> > &mtk_ccifreq_profile,
> > + DEVFREQ_GOV_PASSIVE,
> > + passive_data);
> > + if (IS_ERR(drv->devfreq)) {
> > + ret = -EPROBE_DEFER;
> > + dev_err(dev, "failed to add devfreq device: %ld\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(dev, &drv->opp_nb);
> > + if (ret) {
> > + dev_err(dev, "failed to register opp notifier: %d\n",
> > ret);
> > + goto out_remove_devfreq_device;
> > + }
> > + return 0;
> > +
> > +out_remove_devfreq_device:
> > + devm_devfreq_remove_device(dev, drv->devfreq);
>
> Why is this needed? Should'nt devm_devfreq_add_device() already do
> it?
> It is also not in the remove function.
>
> CJ
>
> > +
> > +out_remove_opp_table:
> > + dev_pm_opp_of_remove_table(dev);
> > +
> > +out_disable_cci_clk:
> > + clk_disable_unprepare(drv->cci_clk);
> > +
> > +out_free_resources:
> > + if (regulator_is_enabled(drv->proc_reg))
> > + regulator_disable(drv->proc_reg);
> > + if (drv->sram_reg && regulator_is_enabled(drv->sram_reg))
> > + regulator_disable(drv->sram_reg);
> > +
> > + return ret;
> > +}
> > +
> > +static int mtk_ccifreq_remove(struct platform_device *pdev)
> > +{
> > + struct device *dev = &pdev->dev;
> > + struct mtk_ccifreq_drv *drv;
> > +
> > + drv = platform_get_drvdata(pdev);
> > +
> > + dev_pm_opp_unregister_notifier(dev, &drv->opp_nb);
> > + dev_pm_opp_of_remove_table(dev);
> > + clk_disable_unprepare(drv->cci_clk);
> > + regulator_disable(drv->proc_reg);
> > + if (drv->sram_reg)
> > + regulator_disable(drv->sram_reg);
> > +
> > + return 0;
> > +}
> > +
> > +static const struct mtk_ccifreq_platform_data mt8183_platform_data
> > = {
> > + .min_volt_shift = 100000,
> > + .max_volt_shift = 200000,
> > + .proc_max_volt = 1150000,
> > +};
> > +
> > +static const struct mtk_ccifreq_platform_data mt8186_platform_data
> > = {
> > + .min_volt_shift = 100000,
> > + .max_volt_shift = 250000,
> > + .proc_max_volt = 1118750,
> > + .sram_min_volt = 850000,
> > + .sram_max_volt = 1118750,
> > +};
> > +
> > +static const struct of_device_id mtk_ccifreq_machines[] = {
> > + { .compatible = "mediatek,mt8183-cci", .data =
> > &mt8183_platform_data },
> > + { .compatible = "mediatek,mt8186-cci", .data =
> > &mt8186_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 = mtk_ccifreq_machines,
> > + },
> > +};
> > +module_platform_driver(mtk_ccifreq_platdrv);
> > +
> > +MODULE_DESCRIPTION("MediaTek CCI devfreq driver");
> > +MODULE_AUTHOR("Jia-Wei Chang <
> > jia-wei.chang-NuS5LvNUpcJWk0Htik3J/w at public.gmane.org>");
> > +MODULE_LICENSE("GPL v2");
>
>
Hi CJ,
Thanks for your suggestion.
I'll modify them in the next version.
BRs,
Johnson Wang
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