[RFC,0/2] Add Mediatek MMDVFS driver

This RFC patch adds the Mediatek MMDVFS(Multimedia Dynamic Voltage and
Frequency Scaling) driver. The multimedia HWs, such as display, camera,
share the same power supplier, and on some platforms, they share the
same clock MUX. If each HW needs different clock frequency at the same
time, the clock MUX must be set to the clock source which can meet the
highest required clock frequency.

Following implementation is used to achieve the goal. There are OPP tables
for all the clock MUXs for MM HWs defined in DTS, ant these OPP tables have
the same number of levels. The MMDVFS registers the regulator callback and
the MM HWs can get available clock frequencies from OPP tables and set
corresponding voltage by regulor API. The MMDVFS's callback will be
triggered if the voltage is changed and this voltage represents the highest
required OPP level. The MMDVFS has a mapping table: which clock source
should be set to each clock MUX for every OPP level. So all the clock MUXs
will be set to the clock sources according to the current OPP level in the
MMDVFS's regulator callback.



Anthony Huang (2):
  dt-bindings: soc: mediatek: Add document for mmdvfs driver
  soc: mediatek: Add mtk-mmdvfs driver

 .../devicetree/bindings/soc/mediatek/mmdvfs.txt    |  149 ++++++++++
 drivers/soc/mediatek/Kconfig                       |    9 +
 drivers/soc/mediatek/Makefile                      |    1 +
 drivers/soc/mediatek/mtk-mmdvfs.c                  |  313 ++++++++++++++++++++
 4 files changed, 472 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/soc/mediatek/mmdvfs.txt
 create mode 100644 drivers/soc/mediatek/mtk-mmdvfs.c

Hi Rob and Matthias,

Gentle ping for this patch set.

Thanks.

On Tue, 2019-10-22 at 11:51 +0800, Anthony Huang wrote:
> Mediatek MMDVFS driver is used to set clk for Mediatek multimedia
> hardwares. The MMDVFS registers a regulator callback and multimedia
> hardwares set voltage by regulator API and then this callback will be
> triggered. The MMDVFS will get current opp level from opp table according
> to the voltage, and then the MMDVFS sets all the clock MUXs to the clock
> sources according to the opp level.
> 
> On some platforms, both clock MUX and frequency hopping need to be used
> together. The MMDVFS supports these two clock setting methods and the
> execution sequence of them can be configured in DTS.
> 
> Signed-off-by: Anthony Huang <anthony.huang@mediatek.com>
> ---
>  drivers/soc/mediatek/Kconfig      |    9 ++
>  drivers/soc/mediatek/Makefile     |    1 +
>  drivers/soc/mediatek/mtk-mmdvfs.c |  313 +++++++++++++++++++++++++++++++++++++
>  3 files changed, 323 insertions(+)
>  create mode 100644 drivers/soc/mediatek/mtk-mmdvfs.c
> 
> diff --git a/drivers/soc/mediatek/Kconfig b/drivers/soc/mediatek/Kconfig
> index 2114b56..e92762b 100644
> --- a/drivers/soc/mediatek/Kconfig
> +++ b/drivers/soc/mediatek/Kconfig
> @@ -44,4 +44,13 @@ config MTK_SCPSYS
>  	  Say yes here to add support for the MediaTek SCPSYS power domain
>  	  driver.
>  
> +config MTK_MMDVFS
> +	tristate "MediaTek MMDVFS Support"
> +	depends on ARCH_MEDIATEK || COMPILE_TEST
> +	help
> +	  Say yes here to add support for the MediaTek Multimedia DVFS (MMDVFS)
> +	  driver. The MMDVFS is used to set clk for Mediatek multimedia hardwares
> +	  , such as display, camera, mdp and video codec. Say no if your device
> +	  does not need to do DVFS for Multimedia hardwares.
> +
>  endmenu
> diff --git a/drivers/soc/mediatek/Makefile b/drivers/soc/mediatek/Makefile
> index b017330..faf52944 100644
> --- a/drivers/soc/mediatek/Makefile
> +++ b/drivers/soc/mediatek/Makefile
> @@ -1,5 +1,6 @@
>  # SPDX-License-Identifier: GPL-2.0-only
>  obj-$(CONFIG_MTK_CMDQ) += mtk-cmdq-helper.o
>  obj-$(CONFIG_MTK_INFRACFG) += mtk-infracfg.o
> +obj-$(CONFIG_MTK_MMDVFS) += mtk-mmdvfs.o
>  obj-$(CONFIG_MTK_PMIC_WRAP) += mtk-pmic-wrap.o
>  obj-$(CONFIG_MTK_SCPSYS) += mtk-scpsys.o
> diff --git a/drivers/soc/mediatek/mtk-mmdvfs.c b/drivers/soc/mediatek/mtk-mmdvfs.c
> new file mode 100644
> index 0000000..f6e45b0
> --- /dev/null
> +++ b/drivers/soc/mediatek/mtk-mmdvfs.c
> @@ -0,0 +1,313 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Copyright (C) 2019 MediaTek Inc.
> + */
> +#include <linux/clk.h>
> +#include <linux/device.h>
> +#include <linux/err.h>
> +#include <linux/module.h>
> +#include <linux/of_device.h>
> +#include <linux/platform_device.h>
> +#include <linux/pm_opp.h>
> +#include <linux/regulator/consumer.h>
> +
> +#define MAX_OPP_NUM (6)
> +#define MAX_MUX_NUM (10)
> +#define MAX_HOPPING_CLK_NUM (2)
> +
> +enum {
> +	ACTION_DEFAULT,
> +	ACTION_IHDM, /* Voltage Increase: Hopping First, Decrease: MUX First*/
> +};
> +
> +struct mmdvfs_mux_data {
> +	const char *mux_name;
> +	struct clk *mux;
> +	struct clk *clk_src[MAX_OPP_NUM];
> +};
> +
> +struct mmdvfs_hopping_data {
> +	const char *hopping_name;
> +	struct clk *hopping_clk;
> +	u32 hopping_rate[MAX_OPP_NUM];
> +};
> +
> +struct mmdvfs_drv_data {
> +	bool need_change_voltage;
> +	u32 request_voltage;
> +	u32 num_muxes;
> +	struct mmdvfs_mux_data muxes[MAX_MUX_NUM];
> +	u32 num_hoppings;
> +	struct mmdvfs_hopping_data hoppings[MAX_HOPPING_CLK_NUM];
> +	u32 action;
> +	struct notifier_block nb;
> +	u32 voltages[MAX_OPP_NUM];
> +};
> +
> +static void set_all_muxes(struct mmdvfs_drv_data *drv_data, u32 opp_level)
> +{
> +	u32 num_muxes = drv_data->num_muxes;
> +	u32 i;
> +	struct clk *mux, *clk_src;
> +	s32 err;
> +
> +	for (i = 0; i < num_muxes; i++) {
> +		mux = drv_data->muxes[i].mux;
> +		clk_src = drv_data->muxes[i].clk_src[opp_level];
> +		err = clk_prepare_enable(mux);
> +
> +		if (err) {
> +			pr_notice("prepare mux(%s) fail:%d opp_level:%d\n",
> +				  drv_data->muxes[i].mux_name, err, opp_level);
> +			continue;
> +		}
> +		err = clk_set_parent(mux, clk_src);
> +		if (err)
> +			pr_notice("set parent(%s) fail:%d opp_level:%d\n",
> +				  drv_data->muxes[i].mux_name, err, opp_level);
> +		clk_disable_unprepare(mux);
> +	}
> +}
> +
> +static void set_all_hoppings(struct mmdvfs_drv_data *drv_data, u32 opp_level)
> +{
> +	u32 num_hoppings = drv_data->num_hoppings;
> +	u32 i, hopping_rate;
> +	struct clk *hopping;
> +	s32 err;
> +
> +	for (i = 0; i < num_hoppings; i++) {
> +		hopping = drv_data->hoppings[i].hopping_clk;
> +		hopping_rate = drv_data->hoppings[i].hopping_rate[opp_level];
> +		err = clk_prepare_enable(hopping);
> +
> +		if (err) {
> +			pr_notice("prepare hopping(%s) fail:%d opp_level:%d\n",
> +				  drv_data->hoppings[i].hopping_name,
> +				  err, opp_level);
> +			continue;
> +		}
> +		err = clk_set_rate(hopping, hopping_rate);
> +		if (err)
> +			pr_notice("set %s rate(%u) fail:%d opp_level:%d\n",
> +				  drv_data->hoppings[i].hopping_name,
> +				  hopping_rate, err, opp_level);
> +		clk_disable_unprepare(hopping);
> +	}
> +}
> +
> +static void set_all_clk(struct mmdvfs_drv_data *drv_data,
> +			u32 voltage, bool vol_inc)
> +{
> +	u32 i;
> +	u32 opp_level;
> +
> +	for (i = 0; i < MAX_OPP_NUM; i++) {
> +		if (drv_data->voltages[i] == voltage) {
> +			opp_level = i;
> +			break;
> +		}
> +	}
> +	if (i == MAX_OPP_NUM) {
> +		pr_notice("voltage(%d) is not found\n", voltage);
> +		return;
> +	}
> +
> +	switch (drv_data->action) {
> +	/* Voltage Increase: Hopping First, Decrease: MUX First*/
> +	case ACTION_IHDM:
> +		if (vol_inc) {
> +			set_all_hoppings(drv_data, opp_level);
> +			set_all_muxes(drv_data, opp_level);
> +		} else {
> +			set_all_muxes(drv_data, opp_level);
> +			set_all_hoppings(drv_data, opp_level);
> +		}
> +		break;
> +	default:
> +		set_all_muxes(drv_data, opp_level);
> +		break;
> +	}
> +	pr_debug("set clk to opp level:%d\n", opp_level);
> +}
> +
> +static int regulator_event_notify(struct notifier_block *nb,
> +				  unsigned long event, void *data)
> +{
> +	unsigned long uV;
> +	struct mmdvfs_drv_data *drv_data;
> +	struct pre_voltage_change_data *pvc_data;
> +
> +	drv_data = container_of(nb, struct mmdvfs_drv_data, nb);
> +
> +	if (event == REGULATOR_EVENT_PRE_VOLTAGE_CHANGE) {
> +		pvc_data = data;
> +		uV = pvc_data->min_uV;
> +
> +		if (uV < pvc_data->old_uV) {
> +			set_all_clk(drv_data, uV, false);
> +			drv_data->request_voltage = uV;
> +		} else if (uV > pvc_data->old_uV) {
> +			drv_data->need_change_voltage = true;
> +		}
> +		pr_debug("regulator event=PRE_VOLTAGE_CHANGE old=%lu new=%lu\n",
> +			 pvc_data->old_uV, pvc_data->min_uV);
> +	} else if (event == REGULATOR_EVENT_VOLTAGE_CHANGE) {
> +		uV = (unsigned long)data;
> +		if (drv_data->need_change_voltage) {
> +			set_all_clk(drv_data, uV, true);
> +			drv_data->need_change_voltage = false;
> +			drv_data->request_voltage = uV;
> +		}
> +		pr_debug("regulator event=VOLTAGE_CHANGE voltage=%lu\n", uV);
> +	} else if (event == REGULATOR_EVENT_ABORT_VOLTAGE_CHANGE) {
> +		uV = (unsigned long)data;
> +		/* If clk was changed, restore to previous setting */
> +		if (uV != drv_data->request_voltage) {
> +			set_all_clk(drv_data, uV,
> +				    uV > drv_data->request_voltage);
> +			drv_data->need_change_voltage = false;
> +			drv_data->request_voltage = uV;
> +		}
> +		pr_info("regulator event=ABORT_VOLTAGE_CHANGE voltage=%lu\n",
> +			uV);
> +	}
> +	return 0;
> +}
> +
> +static const struct of_device_id of_mmdvfs_match_tbl[] = {
> +	{
> +		.compatible = "mediatek,mmdvfs",
> +	},
> +	{}
> +};
> +
> +static int mmdvfs_probe(struct platform_device *pdev)
> +{
> +	struct device *dev = &pdev->dev;
> +	struct mmdvfs_drv_data *drv_data;
> +	struct regulator *reg;
> +	u32 num_mux = 0, num_hopping = 0;
> +	u32 num_clksrc, index, hopping_rate, num_hopping_rate;
> +	struct property *mux_prop, *clksrc_prop;
> +	struct property *hopping_prop, *hopping_rate_prop;
> +	const char *mux_name, *clksrc_name, *hopping_name;
> +	char prop_name[32];
> +	const __be32 *p;
> +	s32 ret;
> +	unsigned long freq;
> +	struct dev_pm_opp *opp;
> +
> +	drv_data = devm_kzalloc(dev, sizeof(*drv_data), GFP_KERNEL);
> +	if (!drv_data)
> +		return -ENOMEM;
> +
> +	of_property_for_each_string(dev->of_node, "mediatek,support_mux",
> +				    mux_prop, mux_name) {
> +		if (num_mux >= MAX_MUX_NUM) {
> +			pr_notice("Too many items in support_mux\n");
> +			return -EINVAL;
> +		}
> +		drv_data->muxes[num_mux].mux = devm_clk_get(dev, mux_name);
> +		drv_data->muxes[num_mux].mux_name = mux_name;
> +		snprintf(prop_name, sizeof(prop_name) - 1,
> +			 "mediatek,mux_%s", mux_name);
> +		num_clksrc = 0;
> +		of_property_for_each_string(dev->of_node, prop_name,
> +					    clksrc_prop, clksrc_name) {
> +			if (num_clksrc >= MAX_OPP_NUM) {
> +				pr_notice("Too many items in %s\n", prop_name);
> +				return -EINVAL;
> +			}
> +			drv_data->muxes[num_mux].clk_src[num_clksrc] =
> +				devm_clk_get(dev, clksrc_name);
> +			num_clksrc++;
> +		}
> +		num_mux++;
> +	}
> +	drv_data->num_muxes = num_mux;
> +
> +	of_property_for_each_string(dev->of_node, "mediatek,support_hopping",
> +				    hopping_prop, hopping_name) {
> +		if (num_hopping >= MAX_HOPPING_CLK_NUM) {
> +			pr_notice("Too many items in support_hopping\n");
> +			return -EINVAL;
> +		}
> +		drv_data->hoppings[num_hopping].hopping_clk =
> +					devm_clk_get(dev, hopping_name);
> +		drv_data->hoppings[num_hopping].hopping_name = hopping_name;
> +		snprintf(prop_name, sizeof(prop_name) - 1,
> +			 "mediatek,hopping_%s", hopping_name);
> +		num_hopping_rate = 0;
> +		of_property_for_each_u32(dev->of_node, prop_name,
> +					 hopping_rate_prop, p, hopping_rate) {
> +			if (num_hopping_rate >= MAX_OPP_NUM) {
> +				pr_notice("Too many items in %s\n", prop_name);
> +				return -EINVAL;
> +			}
> +			drv_data->hoppings[num_hopping].hopping_rate
> +					[num_hopping_rate] = hopping_rate;
> +			num_hopping_rate++;
> +		}
> +		num_hopping++;
> +	}
> +	drv_data->num_hoppings = num_hopping;
> +
> +	of_property_read_u32(dev->of_node,
> +			     "mediatek,action", &drv_data->action);
> +
> +	/* Get voltage info from opp table */
> +	dev_pm_opp_of_add_table(dev);
> +	freq = 0;
> +	index = 0;
> +	while (!IS_ERR(opp = dev_pm_opp_find_freq_ceil(dev, &freq))) {
> +		drv_data->voltages[index] = dev_pm_opp_get_voltage(opp);
> +		freq++;
> +		index++;
> +		dev_pm_opp_put(opp);
> +	}
> +
> +	reg = devm_regulator_get(dev, "dvfsrc-vcore");
> +	if (IS_ERR(reg))
> +		return PTR_ERR(reg);
> +
> +	drv_data->nb.notifier_call = regulator_event_notify;
> +	ret = devm_regulator_register_notifier(reg, &drv_data->nb);
> +	if (ret)
> +		pr_notice("Failed to register notifier: %d\n", ret);
> +
> +	return ret;
> +}
> +
> +static struct platform_driver mmdvfs_drv = {
> +	.probe = mmdvfs_probe,
> +	.driver = {
> +		.name = "mtk-mmdvfs",
> +		.owner = THIS_MODULE,
> +		.of_match_table = of_mmdvfs_match_tbl,
> +	},
> +};
> +
> +static int __init mtk_mmdvfs_init(void)
> +{
> +	s32 status;
> +
> +	status = platform_driver_register(&mmdvfs_drv);
> +	if (status) {
> +		pr_notice("Failed to register MMDVFS driver(%d)\n", status);
> +		return -ENODEV;
> +	}
> +	return 0;
> +}
> +
> +static void __exit mtk_mmdvfs_exit(void)
> +{
> +	platform_driver_unregister(&mmdvfs_drv);
> +}
> +
> +module_init(mtk_mmdvfs_init);
> +module_exit(mtk_mmdvfs_exit);
> +
> +MODULE_DESCRIPTION("MTK MMDVFS driver");
> +MODULE_AUTHOR("Anthony Huang<anthony.huang@mediatek.com>");
> +MODULE_LICENSE("GPL");