linux-kernel - Re: [PATCH v3 12/13] reset: imx: Add audiomix reset controller support

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Date:   Thu, 23 Apr 2020 17:47:33 +0200
From:   Philipp Zabel <p.zabel@...gutronix.de>
To:     Abel Vesa <abel.vesa@....com>, Lee Jones <lee.jones@...aro.org>,
        Shawn Guo <shawnguo@...nel.org>, Peng Fan <peng.fan@....com>,
        Stephen Boyd <sboyd@...nel.org>,
        Sascha Hauer <kernel@...gutronix.de>,
        Anson Huang <anson.huang@....com>,
        Leonard Crestez <leonard.crestez@....com>,
        Jacky Bai <ping.bai@....com>
Cc:     NXP Linux Team <linux-imx@....com>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        devicetree@...r.kernel.org, linux-clk@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH v3 12/13] reset: imx: Add audiomix reset controller
 support

Hi Abel,

On Wed, 2020-04-15 at 11:02 +0300, Abel Vesa wrote:
> The imx-mix MFD driver registers some devices, one of which, in case of
> audiomix, maps correctly to a reset controller type. This driver registers
> a reset controller for that. For now, only the EARC specific resets are added.
> 
> Signed-off-by: Abel Vesa <abel.vesa@....com>
> ---
>  drivers/reset/Kconfig              |   7 +++
>  drivers/reset/Makefile             |   1 +
>  drivers/reset/reset-imx-audiomix.c | 117 +++++++++++++++++++++++++++++++++++++
>  3 files changed, 125 insertions(+)
>  create mode 100644 drivers/reset/reset-imx-audiomix.c
> 
> diff --git a/drivers/reset/Kconfig b/drivers/reset/Kconfig
> index d9efbfd..2f8d9b3 100644
> --- a/drivers/reset/Kconfig
> +++ b/drivers/reset/Kconfig
> @@ -81,6 +81,13 @@ config RESET_INTEL_GW
>  	  Say Y to control the reset signals provided by reset controller.
>  	  Otherwise, say N.
>  
> +config RESET_IMX_AUDIOMIX
> +	bool "i.MX Audiomix Reset Driver" if COMPILE_TEST
> +	depends on HAS_IOMEM
> +	default ARCH_MXC
> +	help
> +	  This enables the audiomix reset controller driver for i.MX SoCs.
> +
>  config RESET_LANTIQ
>  	bool "Lantiq XWAY Reset Driver" if COMPILE_TEST
>  	default SOC_TYPE_XWAY
> diff --git a/drivers/reset/Makefile b/drivers/reset/Makefile
> index 249ed35..cf23d38 100644
> --- a/drivers/reset/Makefile
> +++ b/drivers/reset/Makefile
> @@ -12,6 +12,7 @@ obj-$(CONFIG_RESET_BRCMSTB_RESCAL) += reset-brcmstb-rescal.o
>  obj-$(CONFIG_RESET_HSDK) += reset-hsdk.o
>  obj-$(CONFIG_RESET_IMX7) += reset-imx7.o
>  obj-$(CONFIG_RESET_INTEL_GW) += reset-intel-gw.o
> +obj-$(CONFIG_RESET_IMX_AUDIOMIX) += reset-imx-audiomix.o
>  obj-$(CONFIG_RESET_LANTIQ) += reset-lantiq.o
>  obj-$(CONFIG_RESET_LPC18XX) += reset-lpc18xx.o
>  obj-$(CONFIG_RESET_MESON) += reset-meson.o
> diff --git a/drivers/reset/reset-imx-audiomix.c b/drivers/reset/reset-imx-audiomix.c
> new file mode 100644
> index 00000000..9533e41
> --- /dev/null
> +++ b/drivers/reset/reset-imx-audiomix.c
> @@ -0,0 +1,117 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * Copyright 2019 NXP.
> + */
> +
> +#include <dt-bindings/reset/imx-audiomix-reset.h>
> +#include <linux/err.h>
> +#include <linux/io.h>
> +#include <linux/module.h>
> +#include <linux/of.h>
> +#include <linux/of_address.h>
> +#include <linux/platform_device.h>
> +#include <linux/reset-controller.h>
> +
> +#define IMX_AUDIOMIX_EARC_CTRL_REG	0x200
> +
> +#define IMX_AUDIOMIX_EARC_RESET_BIT	0x0
> +#define IMX_AUDIOMIX_EARC_PHY_RESET_BIT	0x1
> +
> +struct imx_audiomix_reset_data {
> +	void __iomem *base;
> +	struct reset_controller_dev rcdev;
> +	spinlock_t lock;
> +};
> +
> +static int imx_audiomix_reset_set(struct reset_controller_dev *rcdev,
> +			  unsigned long id, bool assert)
> +{
> +	struct imx_audiomix_reset_data *drvdata = container_of(rcdev,
> +			struct imx_audiomix_reset_data, rcdev);
> +	void __iomem *reg_addr = drvdata->base;
> +	unsigned long flags;
> +	unsigned int offset;
> +	u32 reg;
> +
> +	switch (id) {
> +	case IMX_AUDIOMIX_EARC_PHY_RESET:
> +		reg_addr += IMX_AUDIOMIX_EARC_CTRL_REG;
> +		offset = IMX_AUDIOMIX_EARC_PHY_RESET_BIT;
> +		break;
> +	case IMX_AUDIOMIX_EARC_RESET:
> +		reg_addr += IMX_AUDIOMIX_EARC_CTRL_REG;
> +		offset = IMX_AUDIOMIX_EARC_RESET_BIT;
> +		break;

This switch is not necessary. Since reg_addr is the same for both bits,
you can just set it directly, once. And since (IMX_AUDIOMIX_EARC_RESET
== IMX_AUDIOMIX_EARC_RESET_BIT) and (IMX_AUDIOMIX_EARC_PHY_RESET ==
IMX_AUDIOMIX_EARC_PHY_RESET_BIT), you can just use BIT(id) instead of
BIT(offset) below.

> +	default:
> +		return -EINVAL;

This is already catched by the core, which doesn't allow
(id >= rcdev->nr_resets).

> +	}
> +
> +	if (assert) {
> +		spin_lock_irqsave(&drvdata->lock, flags);
> +		reg = readl(reg_addr);
> +		writel(reg & ~BIT(offset), reg_addr);
> +		spin_unlock_irqrestore(&drvdata->lock, flags);
> +	} else {
> +		spin_lock_irqsave(&drvdata->lock, flags);
> +		reg = readl(reg_addr);
> +		writel(reg | BIT(offset), reg_addr);
> +		spin_unlock_irqrestore(&drvdata->lock, flags);
> +	}

regards
Philipp