[PATCH v5 2/2] PM / devfreq: mediatek: Introduce MediaTek CCI devfreq driver
Christophe JAILLET
christophe.jaillet at wanadoo.fr
Fri May 20 06:46:31 PDT 2022
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://git.kernel.org/pub/scm/linux/kernel/git/chanwoo/linux.git/log/?h=devfreq-testing
> ---
> 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");
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