Re: [PATCH 12/18] gpio: add support for the sl28cpld GPIO controller

From: Bartosz Golaszewski
Date: Wed Mar 18 2020 - 05:14:32 EST

wt., 17 mar 2020 o 21:50 Michael Walle <michael@xxxxxxxx> napisaÅ(a):
>
> This adds support for the GPIO controller of the sl28 board management
> controller. This driver is part of a multi-function device.
>
> Signed-off-by: Michael Walle <michael@xxxxxxxx>

Hi Michael,

thanks for the driver. Please take a look at some comments below.

> ---
> drivers/gpio/Kconfig | 11 ++
> drivers/gpio/Makefile | 1 +
> drivers/gpio/gpio-sl28cpld.c | 332 +++++++++++++++++++++++++++++++++++
> 3 files changed, 344 insertions(+)
> create mode 100644 drivers/gpio/gpio-sl28cpld.c
>
> diff --git a/drivers/gpio/Kconfig b/drivers/gpio/Kconfig
> index 3cbf8882a0dd..516e47017ef5 100644
> --- a/drivers/gpio/Kconfig
> +++ b/drivers/gpio/Kconfig
> @@ -1211,6 +1211,17 @@ config GPIO_RC5T583
> This driver provides the support for driving/reading the gpio pins
> of RC5T583 device through standard gpio library.
>
> +config GPIO_SL28CPLD
> + tristate "Kontron sl28 GPIO"
> + depends on MFD_SL28CPLD
> + depends on OF_GPIO
> + select GPIOLIB_IRQCHIP

Please see below - I think both are not needed.

> + help
> + This enables support for the GPIOs found on the Kontron sl28 CPLD.
> +
> + This driver can also be built as a module. If so, the module will be
> + called gpio-sl28cpld.
> +
> config GPIO_STMPE
> bool "STMPE GPIOs"
> depends on MFD_STMPE
> diff --git a/drivers/gpio/Makefile b/drivers/gpio/Makefile
> index 0b571264ddbc..0ca2d52c78e8 100644
> --- a/drivers/gpio/Makefile
> +++ b/drivers/gpio/Makefile
> @@ -127,6 +127,7 @@ obj-$(CONFIG_GPIO_SCH311X) += gpio-sch311x.o
> obj-$(CONFIG_GPIO_SCH) += gpio-sch.o
> obj-$(CONFIG_GPIO_SIFIVE) += gpio-sifive.o
> obj-$(CONFIG_GPIO_SIOX) += gpio-siox.o
> +obj-$(CONFIG_GPIO_SL28CPLD) += gpio-sl28cpld.o
> obj-$(CONFIG_GPIO_SODAVILLE) += gpio-sodaville.o
> obj-$(CONFIG_GPIO_SPEAR_SPICS) += gpio-spear-spics.o
> obj-$(CONFIG_GPIO_SPRD) += gpio-sprd.o
> diff --git a/drivers/gpio/gpio-sl28cpld.c b/drivers/gpio/gpio-sl28cpld.c
> new file mode 100644
> index 000000000000..94f82013882f
> --- /dev/null
> +++ b/drivers/gpio/gpio-sl28cpld.c
> @@ -0,0 +1,332 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * SMARC-sAL28 GPIO driver.
> + *
> + * Copyright 2019 Kontron Europe GmbH
> + */
> +
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/of.h>
> +#include <linux/of_device.h>
> +#include <linux/of_address.h>
> +#include <linux/interrupt.h>
> +#include <linux/regmap.h>
> +#include <linux/platform_device.h>
> +#include <linux/gpio/driver.h>
> +
> +#define GPIO_REG_DIR 0
> +#define GPIO_REG_OUT 1
> +#define GPIO_REG_IN 2
> +#define GPIO_REG_IE 3
> +#define GPIO_REG_IP 4

These values would be more clear if they were defined as hex.

> +
> +#define GPI_REG_IN 0
> +
> +#define GPO_REG_OUT 0

Please also use a common prefix even for defines.

> +
> +enum sl28cpld_gpio_type {
> + sl28cpld_gpio,
> + sl28cpld_gpi,
> + sl28cpld_gpo,
> +};

Enum values should be all upper-case.

> +
> +struct sl28cpld_gpio {
> + struct gpio_chip gpio_chip;
> + struct irq_chip irq_chip;
> + struct regmap *regmap;
> + u32 offset;
> + struct mutex lock;
> + u8 ie;
> +};
> +
> +static void sl28cpld_gpio_set_reg(struct gpio_chip *chip, unsigned int reg,
> + unsigned int offset, int value)
> +{
> + struct sl28cpld_gpio *gpio = gpiochip_get_data(chip);
> + unsigned int mask = 1 << offset;
> + unsigned int val = value << offset;
> +
> + regmap_update_bits(gpio->regmap, gpio->offset + reg, mask, val);
> +}
> +
> +static void sl28cpld_gpio_set(struct gpio_chip *chip, unsigned int offset,
> + int value)
> +{
> + sl28cpld_gpio_set_reg(chip, GPIO_REG_OUT, offset, value);
> +}
> +
> +static void sl28cpld_gpo_set(struct gpio_chip *chip, unsigned int offset,
> + int value)
> +{
> + sl28cpld_gpio_set_reg(chip, GPO_REG_OUT, offset, value);
> +}
> +
> +static int sl28cpld_gpio_get_reg(struct gpio_chip *chip, unsigned int reg,
> + unsigned int offset)
> +{
> + struct sl28cpld_gpio *gpio = gpiochip_get_data(chip);
> + unsigned int mask = 1 << offset;
> + unsigned int val;
> + int ret;
> +
> + ret = regmap_read(gpio->regmap, gpio->offset + reg, &val);
> + if (ret)
> + return ret;
> +
> + return (val & mask) ? 1 : 0;
> +}
> +
> +static int sl28cpld_gpio_get(struct gpio_chip *chip, unsigned int offset)
> +{
> + return sl28cpld_gpio_get_reg(chip, GPIO_REG_IN, offset);
> +}
> +
> +static int sl28cpld_gpi_get(struct gpio_chip *chip, unsigned int offset)
> +{
> + return sl28cpld_gpio_get_reg(chip, GPI_REG_IN, offset);
> +}
> +
> +static int sl28cpld_gpio_get_direction(struct gpio_chip *chip,
> + unsigned int offset)
> +{
> + struct sl28cpld_gpio *gpio = gpiochip_get_data(chip);
> + unsigned int reg;
> + int ret;
> +
> + ret = regmap_read(gpio->regmap, gpio->offset + GPIO_REG_DIR, &reg);
> + if (ret)
> + return ret;
> +
> + if (reg & (1 << offset))
> + return GPIO_LINE_DIRECTION_OUT;
> + else
> + return GPIO_LINE_DIRECTION_IN;
> +}
> +
> +static int sl28cpld_gpio_set_direction(struct gpio_chip *chip,
> + unsigned int offset,
> + bool output)
> +{
> + struct sl28cpld_gpio *gpio = gpiochip_get_data(chip);
> + unsigned int mask = 1 << offset;
> + unsigned int val = (output) ? mask : 0;
> +
> + return regmap_update_bits(gpio->regmap, gpio->offset + GPIO_REG_DIR,
> + mask, val);
> +

Stray newline.

> +}
> +
> +static int sl28cpld_gpio_direction_input(struct gpio_chip *chip,
> + unsigned int offset)
> +{
> + return sl28cpld_gpio_set_direction(chip, offset, false);
> +}
> +
> +static int sl28cpld_gpio_direction_output(struct gpio_chip *chip,
> + unsigned int offset, int value)
> +{
> + sl28cpld_gpio_set_reg(chip, GPIO_REG_OUT, offset, value);
> + return sl28cpld_gpio_set_direction(chip, offset, true);
> +}
> +
> +static void sl28cpld_gpio_irq_lock(struct irq_data *data)
> +{
> + struct sl28cpld_gpio *gpio =
> + gpiochip_get_data(irq_data_get_irq_chip_data(data));
> +
> + mutex_lock(&gpio->lock);

How does that actually lock anything? Regmap uses a different lock and
if you want to make sure nobody modifies the GPIO registers than you'd
need to use the same lock. Also: this looks a lot like a task for
regmap_irqchip - maybe you could use it here or in the core mfd
module?

> +}
> +
> +static void sl28cpld_gpio_irq_sync_unlock(struct irq_data *data)
> +{
> + struct sl28cpld_gpio *gpio =
> + gpiochip_get_data(irq_data_get_irq_chip_data(data));
> +
> + regmap_write(gpio->regmap, gpio->offset + GPIO_REG_IE, gpio->ie);
> + mutex_unlock(&gpio->lock);
> +}
> +
> +static void sl28cpld_gpio_irq_disable(struct irq_data *data)
> +{
> + struct sl28cpld_gpio *gpio =
> + gpiochip_get_data(irq_data_get_irq_chip_data(data));
> +
> + if (data->hwirq >= 8)
> + return;
> +
> + gpio->ie &= ~(1 << data->hwirq);
> +}
> +
> +static void sl28cpld_gpio_irq_enable(struct irq_data *data)
> +{
> + struct sl28cpld_gpio *gpio =
> + gpiochip_get_data(irq_data_get_irq_chip_data(data));
> +
> + if (data->hwirq >= 8)
> + return;
> +
> + gpio->ie |= (1 << data->hwirq);
> +}
> +
> +static int sl28cpld_gpio_irq_set_type(struct irq_data *data, unsigned int type)
> +{
> + /* only edge triggered interrupts on both edges are supported */
> + return (type == IRQ_TYPE_EDGE_BOTH) ? 0 : -EINVAL;
> +}
> +
> +static irqreturn_t sl28cpld_gpio_irq_thread(int irq, void *data)
> +{
> + struct sl28cpld_gpio *gpio = data;
> + unsigned int ip;
> + unsigned int virq;
> + int pin;
> + int ret;
> +
> + ret = regmap_read(gpio->regmap, gpio->offset + GPIO_REG_IP, &ip);
> + if (ret)
> + return IRQ_NONE;
> +
> + /* mask other pending interrupts which are not enabled */
> + ip &= gpio->ie;
> +
> + /* ack the interrupts */
> + regmap_write(gpio->regmap, gpio->offset + GPIO_REG_IP, ip);
> +
> + /* and handle them */
> + while (ip) {
> + pin = __ffs(ip);
> + ip &= ~BIT(pin);
> +
> + virq = irq_find_mapping(gpio->gpio_chip.irq.domain, pin);
> + if (virq)
> + handle_nested_irq(virq);
> + }
> +
> + return IRQ_HANDLED;
> +}

This definitely looks like parts of regmap_irqchip reimplemented.
Please check if you could reuse it - it would save a lot of code.

> +
> +static int sl28_cpld_gpio_irq_init(struct platform_device *pdev, int irq)
> +{
> + struct sl28cpld_gpio *gpio = platform_get_drvdata(pdev);
> + struct irq_chip *irq_chip = &gpio->irq_chip;
> + int ret;
> +
> + irq_chip->name = "sl28cpld-gpio-irq",
> + irq_chip->irq_bus_lock = sl28cpld_gpio_irq_lock,
> + irq_chip->irq_bus_sync_unlock = sl28cpld_gpio_irq_sync_unlock,
> + irq_chip->irq_disable = sl28cpld_gpio_irq_disable,
> + irq_chip->irq_enable = sl28cpld_gpio_irq_enable,
> + irq_chip->irq_set_type = sl28cpld_gpio_irq_set_type,
> + irq_chip->flags = IRQCHIP_SKIP_SET_WAKE,
> +
> + ret = gpiochip_irqchip_add_nested(&gpio->gpio_chip, irq_chip, 0,
> + handle_simple_irq, IRQ_TYPE_NONE);
> + if (ret)
> + return ret;
> +
> + ret = devm_request_threaded_irq(&pdev->dev, irq, NULL,
> + sl28cpld_gpio_irq_thread,
> + IRQF_SHARED | IRQF_ONESHOT,
> + pdev->name, gpio);
> + if (ret)
> + return ret;
> +
> + gpiochip_set_nested_irqchip(&gpio->gpio_chip, irq_chip, irq);
> +
> + return 0;
> +}
> +
> +static int sl28cpld_gpio_probe(struct platform_device *pdev)
> +{
> + enum sl28cpld_gpio_type type =
> + platform_get_device_id(pdev)->driver_data;
> + struct device_node *np = pdev->dev.of_node;
> + struct sl28cpld_gpio *gpio;
> + struct gpio_chip *chip;
> + struct resource *res;
> + bool irq_support = false;
> + int ret;
> + int irq;
> +
> + gpio = devm_kzalloc(&pdev->dev, sizeof(*gpio), GFP_KERNEL);
> + if (!gpio)
> + return -ENOMEM;
> +
> + if (!pdev->dev.parent)
> + return -ENODEV;

Why not check this before allocating any memory?

> +
> + gpio->regmap = dev_get_regmap(pdev->dev.parent, NULL);
> + if (!gpio->regmap)
> + return -ENODEV;
> +
> + res = platform_get_resource(pdev, IORESOURCE_REG, 0);
> + if (!res)
> + return -EINVAL;
> + gpio->offset = res->start;
> +

This isn't how IO resources are used. What are you trying to achieve here?

> + /* initialize struct gpio_chip */
> + mutex_init(&gpio->lock);
> + chip = &gpio->gpio_chip;
> + chip->parent = &pdev->dev;
> + chip->label = dev_name(&pdev->dev);
> + chip->owner = THIS_MODULE;
> + chip->can_sleep = true;
> + chip->base = -1;
> + chip->ngpio = 8;
> +
> + switch (type) {
> + case sl28cpld_gpio:
> + chip->get_direction = sl28cpld_gpio_get_direction;
> + chip->direction_input = sl28cpld_gpio_direction_input;
> + chip->direction_output = sl28cpld_gpio_direction_output;
> + chip->get = sl28cpld_gpio_get;
> + chip->set = sl28cpld_gpio_set;
> + irq_support = true;
> + break;
> + case sl28cpld_gpo:
> + chip->set = sl28cpld_gpo_set;
> + chip->get = sl28cpld_gpi_get;
> + break;
> + case sl28cpld_gpi:
> + chip->get = sl28cpld_gpi_get;
> + break;
> + }
> +
> + ret = devm_gpiochip_add_data(&pdev->dev, chip, gpio);
> + if (ret < 0)
> + return ret;
> +
> + platform_set_drvdata(pdev, gpio);
> +
> + if (irq_support && of_property_read_bool(np, "interrupt-controller")) {

You're depending on OF_GPIO for this one function. Please switch to
device_property_read_bool() instead.

> + irq = platform_get_irq(pdev, 0);
> + if (irq < 0)
> + return ret;
> +
> + ret = sl28_cpld_gpio_irq_init(pdev, irq);
> + if (ret)
> + return ret;
> + }
> +
> + return 0;
> +}
> +
> +static const struct platform_device_id sl28cpld_gpio_id_table[] = {
> + {"sl28cpld-gpio", sl28cpld_gpio},
> + {"sl28cpld-gpi", sl28cpld_gpi},
> + {"sl28cpld-gpo", sl28cpld_gpo},

Could you explain this a bit more? Is this the same component with
input/output-only lines or three different components?

> +};
> +MODULE_DEVICE_TABLE(platform, sl28cpld_gpio_id_table);
> +
> +static struct platform_driver sl28cpld_gpio_driver = {
> + .probe = sl28cpld_gpio_probe,
> + .id_table = sl28cpld_gpio_id_table,
> + .driver = {
> + .name = "sl28cpld-gpio",
> + },
> +};
> +module_platform_driver(sl28cpld_gpio_driver);
> +
> +MODULE_DESCRIPTION("sl28cpld GPIO Driver");
> +MODULE_LICENSE("GPL");

I think you could use a MODULE_ALIAS() here if you want this module to
be loaded automatically by udev.

> --
> 2.20.1
>

Best regards,
Bartosz Golaszewski