On 30/04/18 12:18, Lee Jones wrote:
> On Fri, 27 Apr 2018, matthias.bgg@xxxxxxxxxx wrote:
>
>> From: Matthias Brugger <mbrugger@xxxxxxxx>
>>
>> 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@xxxxxxxx>
>> ---
>> 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@xxxxxxxxx>
>> + *
>> + * Author: Matthias Brugger <matthias.bgg@xxxxxxxxx>
>> + */
>> +
>> +#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.
Regards,
Matthias
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