linux-kernel - Re: [PATCH v2 5/9] drivers: gpio: add QIXIS FPGA GPIO controller

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Message-ID: <jfxasie7r3362tsxscd6bqpoprsj7pgmatlj6jsfgvorkwbor3@xsikgz67p6qb>
Date: Wed, 17 Sep 2025 10:40:37 +0300
From: Ioana Ciornei <ioana.ciornei@....com>
To: Frank Li <Frank.li@....com>
Cc: Rob Herring <robh@...nel.org>, 
	Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor Dooley <conor+dt@...nel.org>, 
	Linus Walleij <linus.walleij@...aro.org>, Bartosz Golaszewski <brgl@...ev.pl>, 
	Shawn Guo <shawnguo@...nel.org>, Michael Walle <mwalle@...nel.org>, Lee Jones <lee@...nel.org>, 
	devicetree@...r.kernel.org, linux-gpio@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 5/9] drivers: gpio: add QIXIS FPGA GPIO controller

On Tue, Sep 16, 2025 at 12:39:02PM -0400, Frank Li wrote:
> On Mon, Sep 15, 2025 at 03:23:50PM +0300, Ioana Ciornei wrote:
> > Add support for the GPIO controller found on some QIXIS FPGAs in
> > Layerscape boards such as LX2160ARDB and LS1046AQDS. This driver is
> > using gpio-regmap.
> >
> > A GPIO controller has a maximum of 8 lines (all found in the same
> > register). Even within the same controller, the GPIO lines' direction is
> > fixed, which mean that both input and output lines are found in the same
> > register. This is why the driver also passed to gpio-regmap the newly
> > added .fixed_direction_output bitmap to represent the true direction of
> > the lines.
> >
> > Signed-off-by: Ioana Ciornei <ioana.ciornei@....com>
> > ---
> > Changes in v2:
> > - Use the newly added .fixed_direction_output bitmap representing
> >   the fixed direction of the GPIO lines.
> >
> >  drivers/gpio/Kconfig           |   9 +++
> >  drivers/gpio/Makefile          |   1 +
> >  drivers/gpio/gpio-qixis-fpga.c | 123 +++++++++++++++++++++++++++++++++
> >  3 files changed, 133 insertions(+)
> >  create mode 100644 drivers/gpio/gpio-qixis-fpga.c
> >
> > diff --git a/drivers/gpio/Kconfig b/drivers/gpio/Kconfig
> > index 886bef9106da..4ca5890007ff 100644
> > --- a/drivers/gpio/Kconfig
> > +++ b/drivers/gpio/Kconfig
> > @@ -1951,6 +1951,15 @@ config GPIO_LATCH
> >  	  Say yes here to enable a driver for GPIO multiplexers based on latches
> >  	  connected to other GPIOs.
> >
> > +config GPIO_QIXIS_FPGA
> > +	tristate "NXP QIXIS FPGA GPIO support"
> > +	depends on MFD_SIMPLE_MFD_I2C || COMPILE_TEST
> > +	select GPIO_REGMAP
> > +	help
> > +	  This enables support for the GPIOs found in the QIXIS FPGA which is
> > +	  integrated on some NXP Layerscape boards such as LX2160ARDB and
> > +	  LS1046AQDS.
> > +
> >  config GPIO_MOCKUP
> >  	tristate "GPIO Testing Driver (DEPRECATED)"
> >  	select IRQ_SIM
> > diff --git a/drivers/gpio/Makefile b/drivers/gpio/Makefile
> > index 379f55e9ed1e..373b1f169558 100644
> > --- a/drivers/gpio/Makefile
> > +++ b/drivers/gpio/Makefile
> > @@ -144,6 +144,7 @@ obj-$(CONFIG_GPIO_PL061)		+= gpio-pl061.o
> >  obj-$(CONFIG_GPIO_PMIC_EIC_SPRD)	+= gpio-pmic-eic-sprd.o
> >  obj-$(CONFIG_GPIO_POLARFIRE_SOC)	+= gpio-mpfs.o
> >  obj-$(CONFIG_GPIO_PXA)			+= gpio-pxa.o
> > +obj-$(CONFIG_GPIO_QIXIS_FPGA)		+= gpio-qixis-fpga.o
> >  obj-$(CONFIG_GPIO_RASPBERRYPI_EXP)	+= gpio-raspberrypi-exp.o
> >  obj-$(CONFIG_GPIO_RC5T583)		+= gpio-rc5t583.o
> >  obj-$(CONFIG_GPIO_RCAR)			+= gpio-rcar.o
> > diff --git a/drivers/gpio/gpio-qixis-fpga.c b/drivers/gpio/gpio-qixis-fpga.c
> > new file mode 100644
> > index 000000000000..23219a634f73
> > --- /dev/null
> > +++ b/drivers/gpio/gpio-qixis-fpga.c
> > @@ -0,0 +1,123 @@
> > +// SPDX-License-Identifier: GPL-2.0-only
> > +/*
> > + * Layerscape GPIO QIXIS FPGA driver
> > + *
> > + * Copyright 2025 NXP
> > + */
> > +
> > +#include <linux/device.h>
> > +#include <linux/gpio/driver.h>
> > +#include <linux/gpio/regmap.h>
> > +#include <linux/kernel.h>
> > +#include <linux/mod_devicetable.h>
> > +#include <linux/module.h>
> > +#include <linux/platform_device.h>
> > +#include <linux/regmap.h>
> > +
> > +enum qixis_cpld_gpio_type {
> > +	LX2160ARDB_GPIO_SFP = 0,
> > +	LS1046AQDS_GPIO_STAT_PRES2,
> > +};
> 
> needn't type at all.
> 

True, I can just pass the u64 bitmap directly as data. Will try.

[snip]

> > +	if (!pdev->dev.parent)
> > +		return -ENODEV;
> > +
> > +	cfg = device_get_match_data(&pdev->dev);
> > +	if (!cfg)
> > +		return -ENODEV;
> 
> Needn't this check.

Ok.

> 
> > +
> > +	ret = device_property_read_u32(&pdev->dev, "reg", &base);
> > +	if (ret)
> > +		return ret;
> > +
> > +	regmap = dev_get_regmap(pdev->dev.parent, NULL);
> > +	if (!regmap) {
> > +		/* In case there is no regmap configured by the parent device,
> > +		 * create our own.
> > +		 */
> 
> /* Use MMIO space */

Ok.


[snip]

> +		config.reg_set_base = GPIO_REGMAP_ADDR(base);
> 
> 
> only two compatibles string in qixis_cpld_gpio_of_match. so it can set
> unconditional.
> 

Fair point. Will change.

Ioana