Re: [PATCH v1 2/9] gpio: Add Nuvoton NCT6694 GPIO support

From: Bartosz Golaszewski
Date: Thu Oct 24 2024 - 05:48:07 EST

On Thu, Oct 24, 2024 at 10:59 AM Ming Yu <a0282524688@xxxxxxxxx> wrote:
>
> This driver supports GPIO and IRQ functionality for NCT6694 MFD
> device based on USB interface.
>
> Signed-off-by: Ming Yu <tmyu0@xxxxxxxxxxx>
> ---
> MAINTAINERS | 1 +
> drivers/gpio/Kconfig | 12 +
> drivers/gpio/Makefile | 1 +
> drivers/gpio/gpio-nct6694.c | 489 ++++++++++++++++++++++++++++++++++++
> 4 files changed, 503 insertions(+)
> create mode 100644 drivers/gpio/gpio-nct6694.c
>
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 30157ca95cf3..2c86d5dab3f1 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -16438,6 +16438,7 @@ NUVOTON NCT6694 MFD DRIVER
> M: Ming Yu <tmyu0@xxxxxxxxxxx>
> L: linux-kernel@xxxxxxxxxxxxxxx
> S: Supported
> +F: drivers/gpio/gpio-nct6694.c
> F: drivers/mfd/nct6694.c
> F: include/linux/mfd/nct6694.h
>
> diff --git a/drivers/gpio/Kconfig b/drivers/gpio/Kconfig
> index d93cd4f722b4..aa78ad9ff4ac 100644
> --- a/drivers/gpio/Kconfig
> +++ b/drivers/gpio/Kconfig
> @@ -1450,6 +1450,18 @@ config GPIO_MAX77650
> GPIO driver for MAX77650/77651 PMIC from Maxim Semiconductor.
> These chips have a single pin that can be configured as GPIO.
>
> +config GPIO_NCT6694
> + tristate "Nuvoton NCT6694 GPIO controller support"
> + depends on MFD_NCT6694
> + select GENERIC_IRQ_CHIP
> + select GPIOLIB_IRQCHIP
> + help
> + This driver supports 8 GPIO pins per bank that can all be interrupt
> + sources.
> +
> + This driver can also be built as a module. If so, the module will be
> + called gpio-nct6694.
> +
> config GPIO_PALMAS
> bool "TI PALMAS series PMICs GPIO"
> depends on MFD_PALMAS
> diff --git a/drivers/gpio/Makefile b/drivers/gpio/Makefile
> index 1429e8c0229b..02c94aa28017 100644
> --- a/drivers/gpio/Makefile
> +++ b/drivers/gpio/Makefile
> @@ -121,6 +121,7 @@ obj-$(CONFIG_GPIO_MXC) += gpio-mxc.o
> obj-$(CONFIG_GPIO_MXS) += gpio-mxs.o
> obj-$(CONFIG_GPIO_NOMADIK) += gpio-nomadik.o
> obj-$(CONFIG_GPIO_NPCM_SGPIO) += gpio-npcm-sgpio.o
> +obj-$(CONFIG_GPIO_NCT6694) += gpio-nct6694.o
> obj-$(CONFIG_GPIO_OCTEON) += gpio-octeon.o
> obj-$(CONFIG_GPIO_OMAP) += gpio-omap.o
> obj-$(CONFIG_GPIO_PALMAS) += gpio-palmas.o
> diff --git a/drivers/gpio/gpio-nct6694.c b/drivers/gpio/gpio-nct6694.c
> new file mode 100644
> index 000000000000..42c0e6e76730
> --- /dev/null
> +++ b/drivers/gpio/gpio-nct6694.c
> @@ -0,0 +1,489 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Nuvoton NCT6694 GPIO controller driver based on USB interface.
> + *
> + * Copyright (C) 2024 Nuvoton Technology Corp.
> + */
> +
> +#include <linux/gpio.h>

Don't include this header. It's documented as obsolete.

> +#include <linux/gpio/driver.h>
> +#include <linux/module.h>
> +#include <linux/interrupt.h>
> +#include <linux/platform_device.h>
> +#include <linux/mfd/core.h>
> +#include <linux/mfd/nct6694.h>
> +

You only use it once, drop it.

> +#define DRVNAME "nct6694-gpio"
> +
> +/* Host interface */
> +#define REQUEST_GPIO_MOD 0xFF
> +#define REQUEST_GPIO_LEN 0x01
> +
> +/* Report Channel */
> +#define GPIO_VER_REG 0x90
> +#define GPIO_VALID_REG 0x110
> +#define GPI_DATA_REG 0x120
> +#define GPO_DIR_REG 0x170
> +#define GPO_TYPE_REG 0x180
> +#define GPO_DATA_REG 0x190
> +
> +#define GPI_STS_REG 0x130
> +#define GPI_CLR_REG 0x140
> +#define GPI_FALLING_REG 0x150
> +#define GPI_RISING_REG 0x160
> +

Please use the NCT6694 prefix for these defines, otherwise it's not
clear whether they come from the driver or from GPIO core.

[]

> +
> +static const char * const nct6694_gpio_name[] = {
> + "NCT6694-GPIO0",
> + "NCT6694-GPIO1",
> + "NCT6694-GPIO2",
> + "NCT6694-GPIO3",
> + "NCT6694-GPIO4",
> + "NCT6694-GPIO5",
> + "NCT6694-GPIO6",
> + "NCT6694-GPIO7",
> + "NCT6694-GPIO8",
> + "NCT6694-GPIO9",
> + "NCT6694-GPIOA",
> + "NCT6694-GPIOB",
> + "NCT6694-GPIOC",
> + "NCT6694-GPIOD",
> + "NCT6694-GPIOE",
> + "NCT6694-GPIOF",
> +};

This looks like it corresponds with the MFD cells and makes me wonder:
am I getting that wrong or do you want to register 0xf GPIO chips? Or
a single GPIO chip with 0xf lines? What is the topology?

> +
> +static int nct6694_gpio_probe(struct platform_device *pdev)
> +{
> + const struct mfd_cell *cell = mfd_get_cell(pdev);
> + struct nct6694 *nct6694 = dev_get_drvdata(pdev->dev.parent);
> + struct nct6694_gpio_data *data;
> + struct gpio_irq_chip *girq;
> + int ret;
> +
> + data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL);
> + if (!data)
> + return -ENOMEM;
> +
> + data->nct6694 = nct6694;
> + data->group = cell->id;
> +
> + data->gpio.label = nct6694_gpio_name[cell->id];
> + data->gpio.direction_input = nct6694_direction_input;
> + data->gpio.get = nct6694_get_value;
> + data->gpio.direction_output = nct6694_direction_output;
> + data->gpio.set = nct6694_set_value;
> + data->gpio.get_direction = nct6694_get_direction;
> + data->gpio.set_config = nct6694_set_config;
> + data->gpio.init_valid_mask = nct6694_init_valid_mask;
> + data->gpio.base = -1;
> + data->gpio.can_sleep = false;
> + data->gpio.owner = THIS_MODULE;
> + data->gpio.ngpio = 8;
> +
> + INIT_WORK(&data->irq_work, nct6694_irq);
> + INIT_WORK(&data->irq_trig_work, nct6694_irq_trig);
> + mutex_init(&data->irq_lock);
> +
> + ret = nct6694_register_handler(nct6694, GPIO_IRQ_STATUS,
> + nct6694_gpio_handler, data);
> + if (ret) {
> + dev_err(&pdev->dev, "%s: Failed to register handler: %pe\n",
> + __func__, ERR_PTR(ret));
> + return ret;
> + }
> +
> + platform_set_drvdata(pdev, data);
> +
> + ret = nct6694_get_irq_trig(data);
> + if (ret)
> + return ret;
> +
> + /* Register gpio chip to GPIO framework */
> + girq = &data->gpio.irq;
> + gpio_irq_chip_set_chip(girq, &nct6694_irq_chip);
> + girq->parent_handler = NULL;
> + girq->num_parents = 0;
> + girq->parents = NULL;
> + girq->default_type = IRQ_TYPE_NONE;
> + girq->handler = handle_level_irq;
> + girq->threaded = true;
> +
> + ret = gpiochip_add_data(&data->gpio, data);
> + if (ret) {
> + dev_err(&pdev->dev, "%s: Failed to register GPIO chip: %pe",
> + __func__, ERR_PTR(ret));
> + return ret;
> + }
> +
> + return 0;
> +}
> +
> +static void nct6694_gpio_remove(struct platform_device *pdev)
> +{
> + struct nct6694_gpio_data *data = platform_get_drvdata(pdev);
> +
> + gpiochip_remove(&data->gpio);

This should be dropped in favor of using devm_gpiochip_add_data().
Especially since you probably want to cancel the irq_work before
removing the chip.

> + cancel_work(&data->irq_work);
> + cancel_work(&data->irq_trig_work);
> +}
> +
> +static struct platform_driver nct6694_gpio_driver = {
> + .driver = {
> + .name = DRVNAME,
> + },
> + .probe = nct6694_gpio_probe,
> + .remove = nct6694_gpio_remove,
> +};
> +
> +static int __init nct6694_init(void)
> +{
> + int err;
> +
> + err = platform_driver_register(&nct6694_gpio_driver);
> + if (!err) {
> + if (err)

If err is equal to 0, check if it's not equal to zero?

> + platform_driver_unregister(&nct6694_gpio_driver);

If platform_driver_register() failed, then the device was never registered.

> + }
> +
> + return err;
> +}
> +subsys_initcall(nct6694_init);

Any reason why this must be initialized earlier? It's a USB driver after all.

> +
> +static void __exit nct6694_exit(void)
> +{
> + platform_driver_unregister(&nct6694_gpio_driver);
> +}
> +module_exit(nct6694_exit);
> +
> +MODULE_DESCRIPTION("USB-GPIO controller driver for NCT6694");
> +MODULE_AUTHOR("Ming Yu <tmyu0@xxxxxxxxxxx>");
> +MODULE_LICENSE("GPL");
> --
> 2.34.1
>

Bart