Re: [v3 03/10] mfd: mtk-mmsys: Add mmsys driver

On Mon, 25 Jun 2018, Matthias Brugger wrote:

On 30/04/18 12:18, Lee Jones wrote:

...

On Fri, 27 Apr 2018, matthias.bgg@kernel.org wrote:

...

From: Matthias Brugger mbrugger@suse.com

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@suse.com

drivers/mfd/Kconfig | 9 ++++++ drivers/mfd/Makefile | 2 ++ drivers/mfd/mtk-mmsys.c | 79 +++++++++++++++++++++++++++++++++++++++++++++++++ 3 files changed, 90 insertions(+) create mode 100644 drivers/mfd/mtk-mmsys.c

diff --git a/drivers/mfd/Kconfig b/drivers/mfd/Kconfig index b860eb5aa194..d23a3b9a2c58 100644 --- a/drivers/mfd/Kconfig +++ b/drivers/mfd/Kconfig @@ -378,6 +378,15 @@ 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 MFD_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 d9d2cf0d32ef..b96118bd68d9 100644 --- a/drivers/mfd/Makefile +++ b/drivers/mfd/Makefile @@ -98,6 +98,8 @@ 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..c802343fb1c6 --- /dev/null +++ b/drivers/mfd/mtk-mmsys.c @@ -0,0 +1,79 @@ +// SPDX-License-Identifier: GPL-2.0+

+/*

• • mtk-mmsys.c -- Mediatek MMSYS multi-function driver
• • Copyright (c) 2018 Matthias Brugger matthias.bgg@gmail.com
• • Author: Matthias Brugger matthias.bgg@gmail.com
• */

+#include <linux/module.h> +#include <linux/init.h> +#include <linux/mfd/core.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) +{

• 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;
  

• }
• ret = devm_mfd_add_devices(&pdev->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;

+};

This driver is pretty pointless. It doesn't actually do anything.

I think you just want to use "simple-mfd" instead.

I think the problem is, that right now we have two drivers which use the same devicetree binding, which are clk and drm driver. With a simple-mfd we would need two compatibles, and this would break backwards compatibility.

So what functionality does this driver provide you with that you do not have currently?