Message-ID: <46b64f2f-4dfd-88d6-77ea-68bc844eee7e@kontron.de>
Date:   Tue, 4 May 2021 12:16:49 +0200
From:   Frieder Schrempf <frieder.schrempf@...tron.de>
To:     "Peng Fan (OSS)" <peng.fan@....nxp.com>, robh+dt@...nel.org,
        shawnguo@...nel.org, s.hauer@...gutronix.de
Cc:     kernel@...gutronix.de, festevam@...il.com, linux-imx@....com,
        p.zabel@...gutronix.de, l.stach@...gutronix.de, krzk@...nel.org,
        agx@...xcpu.org, marex@...x.de, andrew.smirnov@...il.com,
        devicetree@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-kernel@...r.kernel.org, ping.bai@....com, aford173@...il.com,
        abel.vesa@....com, Peng Fan <peng.fan@....com>
Subject: Re: [PATCH V2 3/4] soc: imx: Add generic blk-ctl driver

On 30.04.21 07:27, Peng Fan (OSS) wrote:
> From: Peng Fan <peng.fan@....com>
> 
> The i.MX8MM introduces an IP named BLK_CTL and usually is comprised of
> some GPRs.
> 
> The GPRs has some clock bits and reset bits, but here we take it
> as virtual PDs, because of the clock and power domain A/B lock issue
> when taking it as a clock controller.
> 
> For some bits, it might be good to also make it as a reset controller,
> but to i.MX8MM, we not add that support for now.
> 
> Signed-off-by: Peng Fan <peng.fan@....com>
> ---
>   drivers/soc/imx/Makefile  |   2 +-
>   drivers/soc/imx/blk-ctl.c | 303 ++++++++++++++++++++++++++++++++++++++
>   drivers/soc/imx/blk-ctl.h |  76 ++++++++++
>   3 files changed, 380 insertions(+), 1 deletion(-)
>   create mode 100644 drivers/soc/imx/blk-ctl.c
>   create mode 100644 drivers/soc/imx/blk-ctl.h
> 
> diff --git a/drivers/soc/imx/Makefile b/drivers/soc/imx/Makefile
> index 078dc918f4f3..d3d2b49a386c 100644
> --- a/drivers/soc/imx/Makefile
> +++ b/drivers/soc/imx/Makefile
> @@ -4,4 +4,4 @@ obj-$(CONFIG_ARCH_MXC) += soc-imx.o
>   endif
>   obj-$(CONFIG_HAVE_IMX_GPC) += gpc.o
>   obj-$(CONFIG_IMX_GPCV2_PM_DOMAINS) += gpcv2.o
> -obj-$(CONFIG_SOC_IMX8M) += soc-imx8m.o
> +obj-$(CONFIG_SOC_IMX8M) += soc-imx8m.o blk-ctl.o
> diff --git a/drivers/soc/imx/blk-ctl.c b/drivers/soc/imx/blk-ctl.c
> new file mode 100644
> index 000000000000..1f764dfd308d
> --- /dev/null
> +++ b/drivers/soc/imx/blk-ctl.c
> @@ -0,0 +1,303 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Copyright 2021 NXP.
> + */
> +
> +#include <linux/clk.h>
> +#include <linux/err.h>
> +#include <linux/io.h>
> +#include <linux/module.h>
> +#include <linux/of.h>
> +#include <linux/of_address.h>
> +#include <linux/of_device.h>
> +#include <linux/platform_device.h>
> +#include <linux/pm_runtime.h>
> +#include <linux/regmap.h>
> +#include <linux/slab.h>
> +#include <linux/string.h>
> +#include <linux/types.h>
> +#include <linux/pm_domain.h>
> +#include <linux/reset-controller.h>
> +
> +#include "blk-ctl.h"
> +
> +static inline struct imx_blk_ctl_domain *to_imx_blk_ctl_pd(struct generic_pm_domain *genpd)
> +{
> +	return container_of(genpd, struct imx_blk_ctl_domain, pd);
> +}
> +
> +static int imx_blk_ctl_enable_hsk(struct device *dev)
> +{
> +	struct imx_blk_ctl *blk_ctl = dev_get_drvdata(dev);
> +	const struct imx_blk_ctl_hw *hw = &blk_ctl->dev_data->hw_hsk;
> +	struct regmap *regmap = blk_ctl->regmap;
> +	int ret;
> +
> +

Only one blank line here.

> +	if (hw->flags & IMX_BLK_CTL_PD_RESET)
> +		ret = regmap_update_bits(regmap, hw->rst_offset, hw->rst_mask, hw->rst_mask);

The return value above gets discarded.

> +
> +	ret = regmap_update_bits(regmap, hw->offset, hw->mask, hw->mask);
> +
> +	/* Wait for handshake */
> +	udelay(5);
> +
> +	return ret;
> +}
> +
> +int imx_blk_ctl_power_off(struct generic_pm_domain *domain)
> +{
> +	struct imx_blk_ctl_domain *pd;
> +	struct imx_blk_ctl *blk_ctl;
> +	const struct imx_blk_ctl_hw *hw;
> +	struct regmap *regmap;
> +	int ret;
> +
> +	pd = to_imx_blk_ctl_pd(domain);
> +	blk_ctl = pd->blk_ctl;
> +	regmap = blk_ctl->regmap;
> +	hw = &blk_ctl->dev_data->pds[pd->id];

You could include the assignments above in the declarations.

> +
> +	ret = clk_bulk_prepare_enable(blk_ctl->num_clks, blk_ctl->clks);
> +	if (ret)
> +		return ret;
> +
> +	ret = regmap_update_bits(regmap, hw->offset, hw->mask, 0);

You could use regmap_clear_bits() here.

> +	if (ret)
> +		goto hsk_fail;
> +
> +	if (hw->flags & IMX_BLK_CTL_PD_RESET)
> +		ret = regmap_update_bits(regmap, hw->rst_offset, hw->rst_mask, 0);

You could use regmap_clear_bits() here.
And the return value of regmap_update_bits() potentially gets discarded.

> +
> +	if (atomic_dec_and_test(&blk_ctl->power_count)) {
> +		ret = imx_blk_ctl_enable_hsk(blk_ctl->dev);
> +		if (ret) {
> +			dev_err(blk_ctl->dev, "Hankshake fail\n");

s/Hankshake fail/Handshake failed/

> +			goto hsk_fail;

This goto is redundant.

> +		}
> +	}
> +
> +hsk_fail:
> +	clk_bulk_disable_unprepare(blk_ctl->num_clks, blk_ctl->clks);
> +
> +	return ret;
> +}
> +
> +int imx_blk_ctl_power_on(struct generic_pm_domain *domain)
> +{
> +	struct imx_blk_ctl_domain *pd;
> +	struct regmap *regmap;
> +	const struct imx_blk_ctl_hw *hw;
> +	int ret;
> +	struct imx_blk_ctl *blk_ctl;
> +
> +	pd = to_imx_blk_ctl_pd(domain);
> +	blk_ctl = pd->blk_ctl;
> +	regmap = blk_ctl->regmap;
> +	hw = &blk_ctl->dev_data->pds[pd->id];

You could include the assignments above in the declarations.

> +
> +	ret = clk_bulk_prepare_enable(blk_ctl->num_clks, blk_ctl->clks);
> +	if (ret)
> +		return ret;
> +
> +	if ((atomic_read(&blk_ctl->power_count) == 0)) {
> +		ret = imx_blk_ctl_enable_hsk(blk_ctl->dev);
> +		if (ret) {
> +			dev_err(blk_ctl->dev, "Hankshake fail\n");

s/Hankshake fail/Handshake failed/

> +			goto disable_clk;
> +		}
> +	}
> +
> +	if (hw->flags & IMX_BLK_CTL_PD_RESET)
> +		ret = regmap_update_bits(regmap, hw->rst_offset, hw->rst_mask, 0);

You could use regmap_clear_bits() here.
And the return value of regmap_update_bits() gets discarded.

> +
> +	/* Wait for reset propagate */
> +	udelay(5);
> +
> +	if (hw->flags & IMX_BLK_CTL_PD_RESET)
> +		ret = regmap_update_bits(regmap, hw->rst_offset, hw->rst_mask, hw->rst_mask);

The return value above gets discarded.

> +
> +	ret = regmap_update_bits(regmap, hw->offset, hw->mask, hw->mask);
> +	if (ret)
> +		goto disable_clk;
> +
> +	atomic_inc(&blk_ctl->power_count);
> +
> +disable_clk:
> +	clk_bulk_disable_unprepare(blk_ctl->num_clks, blk_ctl->clks);
> +
> +	return ret;
> +}
> +
> +static int imx_blk_ctl_attach_pd(struct device *dev, struct device **devs, char **pd_names,
> +				 u32 num_pds)
> +{
> +	int i, ret;
> +
> +	if (!pd_names)
> +		return 0;
> +
> +	if (dev->pm_domain) {
> +		devs[0] = dev;
> +		pm_runtime_enable(dev);
> +		return 0;
> +	}
> +
> +	for (i = 0; i < num_pds; i++) {
> +		devs[i] = dev_pm_domain_attach_by_name(dev, pd_names[i]);
> +		if (IS_ERR_OR_NULL(devs[i])) {
> +			ret = PTR_ERR(devs[i]) ? : -ENODATA;
> +			goto detach_pm;
> +		}
> +	}
> +
> +	return 0;
> +
> +detach_pm:
> +	for (i--; i >= 0; i--)
> +		dev_pm_domain_detach(devs[i], false);

It looks like you should add pm_runtime_disable() in this error path to 
not leave the pm_runtime_enable() unmatched.

> +
> +	return ret;
> +}
> +
> +static int imx_blk_ctl_register_pd(struct device *dev)
> +{
> +	struct imx_blk_ctl *blk_ctl = dev_get_drvdata(dev);
> +	const struct imx_blk_ctl_dev_data *dev_data = blk_ctl->dev_data;
> +	int num = dev_data->pds_num;
> +	struct imx_blk_ctl_domain *domain;
> +	int i, ret;
> +
> +	blk_ctl->onecell_data.num_domains = num;
> +	blk_ctl->onecell_data.domains = devm_kcalloc(dev, num,
> +						     sizeof(struct generic_pm_domain *),
> +						     GFP_KERNEL);
> +
> +	if (!blk_ctl->onecell_data.domains)
> +		return -ENOMEM;
> +
> +	for (i = 0; i < num; i++) {
> +		domain = devm_kzalloc(dev, sizeof(*domain), GFP_KERNEL);
> +		if (!domain) {
> +			ret = -ENOMEM;
> +			goto remove_genpd;
> +		}
> +		domain->pd.name = dev_data->pds[i].name;
> +		domain->pd.power_off = imx_blk_ctl_power_off;
> +		domain->pd.power_on = imx_blk_ctl_power_on;
> +		domain->blk_ctl = blk_ctl;
> +		domain->id = i;
> +
> +		ret = pm_genpd_init(&domain->pd, NULL, true);
> +		if (ret)
> +			return ret;

Looks like you should use the error path here and "goto remove_genpd" 
instead of return.

> +
> +		blk_ctl->onecell_data.domains[i] = &domain->pd;
> +	}
> +
> +	return 0;
> +
> +remove_genpd:
> +	for (i = i - 1; i >= 0; i--)
> +		pm_genpd_remove(blk_ctl->onecell_data.domains[i]);
> +
> +	return ret;
> +}
> +
> +static int imx_blk_ctl_hook_pd(struct device *dev)
> +{
> +	struct imx_blk_ctl *blk_ctl = dev_get_drvdata(dev);
> +	const struct imx_blk_ctl_dev_data *dev_data = blk_ctl->dev_data;
> +	const struct imx_blk_ctl_hw *pds = dev_data->pds;
> +	int num_active_pd = dev_data->num_active_pd;
> +	int num = dev_data->pds_num;
> +	struct generic_pm_domain *genpd, *child_genpd;
> +	int ret;
> +	int i, j;
> +
> +	blk_ctl->active_pds = devm_kcalloc(dev, num_active_pd, sizeof(struct device *), GFP_KERNEL);
> +	if (!blk_ctl->active_pds)
> +		return -ENOMEM;
> +
> +	ret = imx_blk_ctl_attach_pd(dev, blk_ctl->active_pds, dev_data->active_pd_names,
> +				    num_active_pd);
> +	if (ret) {
> +		if (ret == -EPROBE_DEFER)
> +			return ret;
> +		dev_err(dev, "Failed to attach active pd: %d\n", ret);
> +		return ret;

I think it would be better to do it the other way round:

                 if (ret != -EPROBE_DEFER)
	            dev_err(dev, "Failed to attach active pd: %d\n", ret);
                 return ret;

> +	}
> +
> +	for (i = 0; i < num; i++) {
> +		for (j = 0; j < num_active_pd; j++) {
> +			genpd = pd_to_genpd(blk_ctl->active_pds[j]->pm_domain);
> +			if (!strcmp(genpd->name, pds[i].parent_name))
> +				break;
> +		}
> +
> +		child_genpd = blk_ctl->onecell_data.domains[i];
> +		if (pm_genpd_add_subdomain(genpd, child_genpd))
> +			pr_warn("failed to add subdomain:\n");

Remove the colon add the end of the warning message or add something 
after it.

> +	}
> +
> +	return 0;
> +}
> +
> +int imx_blk_ctl_register(struct device *dev)
> +{
> +	struct imx_blk_ctl *blk_ctl = dev_get_drvdata(dev);
> +	const struct imx_blk_ctl_dev_data *dev_data = blk_ctl->dev_data;
> +	int num = dev_data->pds_num;
> +	int i, ret;
> +
> +	if (!blk_ctl)
> +		return -ENODEV;
> +
> +	ret = imx_blk_ctl_register_pd(dev);
> +	if (ret)
> +		return ret;
> +
> +	ret = imx_blk_ctl_hook_pd(dev);
> +	if (ret)
> +		goto unregister_pd;
> +
> +	ret = of_genpd_add_provider_onecell(dev->of_node, &blk_ctl->onecell_data);
> +	if (ret)
> +		goto detach_pd;
> +
> +	pm_runtime_get_noresume(dev);
> +	pm_runtime_set_active(dev);
> +	pm_runtime_enable(dev);
> +
> +	pm_runtime_put(dev);
> +
> +	return 0;
> +
> +detach_pd:
> +	for (i = blk_ctl->dev_data->num_active_pd; i >= 0; i--)
> +		dev_pm_domain_detach(blk_ctl->active_pds[i], false);
> +unregister_pd:
> +	for (i = num - 1; i >= 0; i--)
> +		pm_genpd_remove(blk_ctl->onecell_data.domains[i]);
> +
> +	return ret;
> +}
> +EXPORT_SYMBOL_GPL(imx_blk_ctl_register);
> +
> +static int __maybe_unused imx_blk_ctl_runtime_suspend(struct device *dev)
> +{
> +	return 0;
> +}
> +
> +static int __maybe_unused imx_blk_ctl_runtime_resume(struct device *dev)
> +{
> +	return 0;
> +}
> +
> +const struct dev_pm_ops imx_blk_ctl_pm_ops = {
> +	SET_RUNTIME_PM_OPS(imx_blk_ctl_runtime_suspend,
> +			   imx_blk_ctl_runtime_resume, NULL)
> +	SET_SYSTEM_SLEEP_PM_OPS(pm_runtime_force_suspend,
> +			   pm_runtime_force_resume)
> +};
> +EXPORT_SYMBOL_GPL(imx_blk_ctl_pm_ops);
> diff --git a/drivers/soc/imx/blk-ctl.h b/drivers/soc/imx/blk-ctl.h
> new file mode 100644
> index 000000000000..e736369406a1
> --- /dev/null
> +++ b/drivers/soc/imx/blk-ctl.h
> @@ -0,0 +1,76 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +#ifndef __SOC_IMX_BLK_CTL_H
> +#define __SOC_IMX_BLK_CTL_H
> +
> +enum imx_blk_ctl_pd_type {
> +	BLK_CTL_PD,
> +};
> +
> +struct imx_blk_ctl_hw {
> +	int type;
> +	char *name;
> +	char *parent_name;
> +	u32 offset;
> +	u32 mask;
> +	u32 flags;
> +	u32 id;
> +	u32 rst_offset;
> +	u32 rst_mask;
> +};
> +
> +struct imx_blk_ctl_domain {
> +	struct generic_pm_domain pd;
> +	struct imx_blk_ctl *blk_ctl;
> +	u32 id;
> +};
> +
> +struct imx_blk_ctl_dev_data {
> +	struct regmap_config config;
> +	struct imx_blk_ctl_hw *pds;
> +	struct imx_blk_ctl_hw hw_hsk;
> +	u32 pds_num;
> +	char **active_pd_names;
> +	u32 num_active_pd;
> +};
> +
> +struct imx_blk_ctl {
> +	struct device *dev;
> +	struct regmap *regmap;
> +	struct device **active_pds;
> +	u32 pds_num;
> +	u32 active_pd_count;
> +	struct genpd_onecell_data onecell_data;
> +	const struct imx_blk_ctl_dev_data *dev_data;
> +	struct clk_bulk_data *clks;
> +	u32 num_clks;
> +
> +	atomic_t power_count;
> +};
> +
> +#define IMX_BLK_CTL(_type, _name, _parent_name, _id, _offset, _mask, _rst_offset, _rst_mask,	\
> +		    _flags)								\
> +	{										\
> +		.type = _type,								\
> +		.name = _name,								\
> +		.parent_name = _parent_name,						\
> +		.id = _id,								\
> +		.offset = _offset,							\
> +		.mask = _mask,								\
> +		.flags = _flags,							\
> +		.rst_offset = _rst_offset,						\
> +		.rst_mask = _rst_mask,							\
> +	}
> +
> +#define IMX_BLK_CTL_PD(_name, _parent_name, _id, _offset, _mask, _rst_offset, _rst_mask, _flags) \
> +	IMX_BLK_CTL(BLK_CTL_PD, _name, _parent_name, _id, _offset, _mask, _rst_offset,		\
> +		    _rst_mask, _flags)
> +
> +int imx_blk_ctl_register(struct device *dev);
> +
> +#define IMX_BLK_CTL_PD_HANDSHAKE	BIT(0)
> +#define IMX_BLK_CTL_PD_RESET		BIT(1)
> +#define IMX_BLK_CTL_PD_BUS		BIT(2)
> +
> +const extern struct dev_pm_ops imx_blk_ctl_pm_ops;
> +
> +#endif
> 

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