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Date:   Thu, 23 Nov 2017 10:09:05 +0100
From:   Philipp Zabel <p.zabel@...gutronix.de>
To:     Matthias Brugger <matthias.bgg@...il.com>,
        ulrich.hecht+renesas@...il.com, laurent.pinchart@...asonboard.com,
        ck.hu@...iatek.com, airlied@...ux.ie, robh+dt@...nel.org,
        mark.rutland@....com, mturquette@...libre.com,
        sboyd@...eaurora.org, lee.jones@...aro.org
Cc:     davem@...emloft.net, gregkh@...uxfoundation.org,
        mchehab@...nel.org, rdunlap@...radead.org,
        pi-cheng.chen@...aro.org, sean.wang@...iatek.com,
        linux-clk@...r.kernel.org, linux@...linux.org.uk,
        dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        linux-mediatek@...ts.infradead.org,
        Matthias Brugger <mbrugger@...e.com>
Subject: Re: [PATCH 2/8] mfd: mtk-mmsys: Add mmsys driver

Hi Matthias,

On Tue, 2017-11-14 at 22:41 +0100, Matthias Brugger wrote:
> The MMSYS subsystem includes clocks and drm components.
> This patch adds a MFD device to probe both drivers from the same
> device tree compatible.
> 
> Signed-off-by: Matthias Brugger <mbrugger@...e.com>
> ---
>  drivers/mfd/Kconfig       |  9 +++++
>  drivers/mfd/Makefile      |  2 ++
>  drivers/mfd/mtk-mmsys.c   | 91 +++++++++++++++++++++++++++++++++++++++++++++++
>  include/linux/mfd/mmsys.h | 18 ++++++++++
>  4 files changed, 120 insertions(+)
>  create mode 100644 drivers/mfd/mtk-mmsys.c
>  create mode 100644 include/linux/mfd/mmsys.h
> 
> diff --git a/drivers/mfd/Kconfig b/drivers/mfd/Kconfig
> index fc5e4fef89d2..3250ce5d205a 100644
> --- a/drivers/mfd/Kconfig
> +++ b/drivers/mfd/Kconfig
> @@ -368,6 +368,15 @@ config MFD_MC13XXX_I2C
>  	help
>  	  Select this if your MC13xxx is connected via an I2C bus.
>  
> +config MFD_MEDIATEK_MMSYS
> +	tristate "Mediatek MMSYS interface"
> +	select MDF_CORE
> +	select REGMAP_MMIO
> +	help
> +	  Select this if you have a MMSYS subsystem in your SoC. The
> +	  MMSYS subsystem has at least a clock driver part and some
> +	  DRM components.
> +
>  config MFD_MXS_LRADC
>  	tristate "Freescale i.MX23/i.MX28 LRADC"
>  	depends on ARCH_MXS || COMPILE_TEST
> diff --git a/drivers/mfd/Makefile b/drivers/mfd/Makefile
> index 8703ff17998e..d4fc99df784c 100644
> --- a/drivers/mfd/Makefile
> +++ b/drivers/mfd/Makefile
> @@ -100,6 +100,8 @@ obj-$(CONFIG_MFD_MC13XXX)	+= mc13xxx-core.o
>  obj-$(CONFIG_MFD_MC13XXX_SPI)	+= mc13xxx-spi.o
>  obj-$(CONFIG_MFD_MC13XXX_I2C)	+= mc13xxx-i2c.o
>  
> +obj-$(CONFIG_MFD_MEDIATEK_MMSYS) += mtk-mmsys.o
> +
>  obj-$(CONFIG_MFD_CORE)		+= mfd-core.o
>  
>  obj-$(CONFIG_EZX_PCAP)		+= ezx-pcap.o
> diff --git a/drivers/mfd/mtk-mmsys.c b/drivers/mfd/mtk-mmsys.c
> new file mode 100644
> index 000000000000..102b491aa28f
> --- /dev/null
> +++ b/drivers/mfd/mtk-mmsys.c
> @@ -0,0 +1,91 @@
> +/*
> + * mtk-mmsys.c  --  Mediatek MMSYS multi-function driver
> + *
> + *  Copyright (c) 2017 Matthias Brugger <matthias.bgg@...il.com>
> + *
> + * Author: Matthias Brugger <matthias.bgg@...il.com>
> + *
> + * For licencing details see kernel-base/COPYING
> + *
> + */
> +
> +#include <linux/module.h>
> +#include <linux/init.h>
> +#include <linux/mfd/core.h>
> +#include <linux/mfd/mmsys.h>
> +#include <linux/of.h>
> +#include <linux/of_address.h>
> +#include <linux/of_device.h>
> +#include <linux/platform_device.h>
> +#include <linux/regmap.h>
> +
> +enum {
> +	MMSYS_MT2701 = 1,
> +};
> +
> +static const struct mfd_cell mmsys_mt2701_devs[] = {
> +	{ .name = "clk-mt2701-mm", },
> +	{ .name = "drm-mt2701-mm", },
> +};
> +
> +static int mmsys_probe(struct platform_device *pdev)
> +{
> +	struct mmsys_dev *private;
> +	const struct mfd_cell *mmsys_cells;
> +	int nr_cells;
> +	long id;
> +	int ret;
> +
> +	id = (long) of_device_get_match_data(&pdev->dev);
> +	if (!id) {
> +		dev_err(&pdev->dev, "of_device_get match_data() failed\n");
> +		return -EINVAL;
> +	}
> +
> +	switch (id) {
> +	case MMSYS_MT2701:
> +		mmsys_cells = mmsys_mt2701_devs;
> +		nr_cells = ARRAY_SIZE(mmsys_mt2701_devs);
> +		break;
> +	default:
> +		return -ENODEV;
> +	}
> +
> +	private = devm_kzalloc(&pdev->dev, sizeof(*private), GFP_KERNEL);
> +	if (!private)
> +		return -ENOMEM;
> +
> +	private->dev = &pdev->dev;
> +	dev_set_drvdata(private->dev, private);
> +
> +	private->of_node = pdev->dev.of_node;

This seems superfluous to me. The of_node can be obtained from the
device, and the device itself is already needed to get to the drvdata.

Instead of

	mmsys_private = drv_get_drvdata(pdev->dev.parent);
	mmsys_dev = mmsys_private.dev;
	mmsys_of_node = mmsys_private.of_node;

couldn't the mfd children just do

	mmsys_dev = pdev->dev.parent;
	mmsys_of_node = pdev->dev.parent->of_node;

?

> +
> +	ret = devm_mfd_add_devices(private->dev, 0, mmsys_cells, nr_cells,
> +					NULL, 0, NULL);
> +	if (ret) {
> +		dev_err(&pdev->dev, "failed to add MFD devices %d\n", ret);
> +		return ret;
> +	}
> +
> +	return 0;
> +};
> +
> +static const struct of_device_id of_match_mmsys[] = {
> +	{ .compatible = "mediatek,mt2701-mmsys",
> +	  .data = (void *) MMSYS_MT2701,
> +	},
> +	{ /* sentinel */ },
> +};
> +
> +static struct platform_driver mmsys_drv = {
> +	.probe = mmsys_probe,
> +	.driver = {
> +		.name = "mediatek-mmysys",
> +		.of_match_table = of_match_ptr(of_match_mmsys),
> +	},
> +};
> +
> +builtin_platform_driver(mmsys_drv);
> +
> +MODULE_DESCRIPTION("Mediatek MMSYS multi-function driver");
> +MODULE_LICENSE("GPL");
> diff --git a/include/linux/mfd/mmsys.h b/include/linux/mfd/mmsys.h
> new file mode 100644
> index 000000000000..274b9ee03ada
> --- /dev/null
> +++ b/include/linux/mfd/mmsys.h
> @@ -0,0 +1,18 @@
> +/* Header of MMSYS MFD core driver for Mediatek platforms
> + *
> + * Copyright (c) 2017 Matthias Brugger <matthias.bgg@...il.com>
> + *
> + * This program is free software; you can redistribute it and/or modify it under
> + * the terms of the GNU General Public License version 2 as published by the
> + * Free Software Foundation.
> + */
> +
> +#ifndef __MEDIATEK_MMSYS__H__
> +#define __MEDIATEK_MMSYS__H__
> +
> +struct mmsys_dev {
> +	struct device		*dev;
> +	struct device_node	*of_node;
> +};

This wouldn't be needed, then.

regards
Philipp

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