linux-kernel - Re: [PATCH v2 11/17] clk: imx: Add blk

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Message-ID: <ea2563fcb456830b37b0031455e5054d6b81c680.camel@pengutronix.de>
Date:   Tue, 25 Aug 2020 12:48:41 +0200
From:   Philipp Zabel <p.zabel@...gutronix.de>
To:     Abel Vesa <abel.vesa@....com>,
        Mike Turquette <mturquette@...libre.com>,
        Stephen Boyd <sboyd@...nel.org>, Rob Herring <robh@...nel.org>,
        Shawn Guo <shawnguo@...nel.org>,
        Sascha Hauer <kernel@...gutronix.de>,
        Fabio Estevam <fabio.estevam@....com>,
        Anson Huang <anson.huang@....com>,
        Jacky Bai <ping.bai@....com>, Peng Fan <peng.fan@....com>,
        Dong Aisheng <aisheng.dong@....com>,
        Fugang Duan <fugang.duan@....com>, devicetree@...r.kernel.org
Cc:     NXP Linux Team <linux-imx@....com>,
        linux-arm-kernel@...ts.infradead.org,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        linux-clk@...r.kernel.org
Subject: Re: [PATCH v2 11/17] clk: imx: Add blk_ctrl combo driver

On Fri, 2020-08-14 at 15:09 +0300, Abel Vesa wrote:
> On i.MX8MP, there is a new type of IP which is called BLK_CTRL in
> RM and usually is comprised of some GPRs that are considered too
> generic to be part of any dedicated IP from that specific subsystem.
> 
> In general, some of the GPRs have some clock bits, some have reset bits,
> so in order to be able to use the imx clock API, this needs to be
> in a clock driver. From there it can use the reset controller API and
> leave the rest to the syscon.
> 
> This driver is intended to work with the following BLK_CTRL IPs found in
> i.MX8MP (but it might be reused by the future i.MX platforms that
> have this kind of IP in their design):
>  - Audio
>  - Media
>  - HDMI
> 
> Signed-off-by: Abel Vesa <abel.vesa@....com>
> ---
>  drivers/clk/imx/Makefile       |   2 +-
>  drivers/clk/imx/clk-blk-ctrl.c | 327 +++++++++++++++++++++++++++++++++++++++++
>  drivers/clk/imx/clk-blk-ctrl.h |  81 ++++++++++
>  3 files changed, 409 insertions(+), 1 deletion(-)
>  create mode 100644 drivers/clk/imx/clk-blk-ctrl.c
>  create mode 100644 drivers/clk/imx/clk-blk-ctrl.h
> 
> diff --git a/drivers/clk/imx/Makefile b/drivers/clk/imx/Makefile
> index 928f874c..7afe1df 100644
> --- a/drivers/clk/imx/Makefile
> +++ b/drivers/clk/imx/Makefile
> @@ -27,7 +27,7 @@ obj-$(CONFIG_MXC_CLK_SCU) += \
>  
>  obj-$(CONFIG_CLK_IMX8MM) += clk-imx8mm.o
>  obj-$(CONFIG_CLK_IMX8MN) += clk-imx8mn.o
> -obj-$(CONFIG_CLK_IMX8MP) += clk-imx8mp.o
> +obj-$(CONFIG_CLK_IMX8MP) += clk-imx8mp.o clk-blk-ctrl.o
>  obj-$(CONFIG_CLK_IMX8MQ) += clk-imx8mq.o
>  obj-$(CONFIG_CLK_IMX8QXP) += clk-imx8qxp.o clk-imx8qxp-lpcg.o
>  
> diff --git a/drivers/clk/imx/clk-blk-ctrl.c b/drivers/clk/imx/clk-blk-ctrl.c
> new file mode 100644
> index 00000000..1672646
> --- /dev/null
> +++ b/drivers/clk/imx/clk-blk-ctrl.c
> @@ -0,0 +1,327 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * Copyright 2020 NXP.
> + */
> +
> +#include <linux/clk.h>
> +#include <linux/reset-controller.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/slab.h>
> +#include <linux/string.h>
> +#include <linux/types.h>
> +
> +#include "clk.h"
> +#include "clk-blk-ctrl.h"
> +
> +struct reset_hw {
> +	u32 offset;
> +	u32 shift;
> +	u32 mask;
> +	bool asserted;
> +};
> +
> +struct pm_safekeep_info {
> +	uint32_t *regs_values;
> +	uint32_t *regs_offsets;
> +	uint32_t regs_num;
> +};
> +
> +struct imx_blk_ctrl_drvdata {
> +	void __iomem *base;
> +	struct reset_controller_dev rcdev;
> +	struct reset_hw *rst_hws;
> +	struct pm_safekeep_info pm_info;
> +
> +	spinlock_t lock;
> +};
> +
> +static int imx_blk_ctrl_reset_set(struct reset_controller_dev *rcdev,
> +				  unsigned long id, bool assert)
> +{
> +	struct imx_blk_ctrl_drvdata *drvdata = container_of(rcdev,
> +			struct imx_blk_ctrl_drvdata, rcdev);
> +	unsigned int offset = drvdata->rst_hws[id].offset;
> +	unsigned int shift = drvdata->rst_hws[id].shift;
> +	unsigned int mask = drvdata->rst_hws[id].mask;
> +	void __iomem *reg_addr = drvdata->base + offset;
> +	unsigned long flags;
> +	unsigned int asserted_before = 0, asserted_after = 0;
> +	u32 reg;
> +	int i;
> +
> +	spin_lock_irqsave(&drvdata->lock, flags);
> +
> +	for (i = 0; i < drvdata->rcdev.nr_resets; i++)
> +		if (drvdata->rst_hws[i].asserted)
> +			asserted_before++;
> +
> +	if (asserted_before == 0 && assert)
> +		pm_runtime_get(rcdev->dev);

Shouldn't that be pm_runtime_get_sync() ?

I would do that unconditionally before locking drvdata->lock and then
drop unnecessary refcounts afterwards.

> +
> +	if (assert) {
> +		reg = readl(reg_addr);
> +		writel(reg & ~(mask << shift), reg_addr);
> +		drvdata->rst_hws[id].asserted = true;
> +	} else {
> +		reg = readl(reg_addr);
> +		writel(reg | (mask << shift), reg_addr);
> +		drvdata->rst_hws[id].asserted = false;
> +	}
> +
> +	for (i = 0; i < drvdata->rcdev.nr_resets; i++)
> +		if (drvdata->rst_hws[i].asserted)
> +			asserted_after++;
> +
> +	if (asserted_before == 1 && asserted_after == 0)
> +		pm_runtime_put(rcdev->dev);
> +
> +	spin_unlock_irqrestore(&drvdata->lock, flags);
> +
> +	return 0;
> +}

regards
Philipp