linux-kernel - Re: [PATCH v5 4/4] gpio: add support for the Diolan DLN-2 USB GPIO driver

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Date:	Wed, 24 Sep 2014 14:39:05 +0200
From:	Johan Hovold <johan@...nel.org>
To:	Octavian Purdila <octavian.purdila@...el.com>
Cc:	gregkh@...uxfoundation.org, linus.walleij@...aro.org,
	gnurou@...il.com, wsa@...-dreams.de, sameo@...ux.intel.com,
	lee.jones@...aro.org, arnd@...db.de, johan@...nel.org,
	daniel.baluta@...el.com, laurentiu.palcu@...el.com,
	linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org,
	linux-gpio@...r.kernel.org, linux-i2c@...r.kernel.org
Subject: Re: [PATCH v5 4/4] gpio: add support for the Diolan DLN-2 USB GPIO
 driver

On Fri, Sep 19, 2014 at 11:22:45PM +0300, Octavian Purdila wrote:

> +struct dln2_gpio {
> +	struct platform_device *pdev;
> +	struct gpio_chip gpio;
> +
> +	/*
> +	 * Cache pin direction to save us one transfer, since the
> +	 * hardware has separate commands to read the in and out
> +	 * values. Bit set for out, bit clear for in.
> +	 */
> +	DECLARE_BITMAP(pin_dir, DLN2_GPIO_MAX_PINS);

Using the more common name output_enabled might be preferred? Then you
can even get rid of (part of) the comment.

> +
> +	DECLARE_BITMAP(irqs_masked, DLN2_GPIO_MAX_PINS);
> +	DECLARE_BITMAP(irqs_enabled, DLN2_GPIO_MAX_PINS);
> +	DECLARE_BITMAP(irqs_pending, DLN2_GPIO_MAX_PINS);
> +	struct dln2_irq_work *irq_work;
> +};

[...]

> +#define DLN2_GPIO_DIRECTION_IN		0
> +#define DLN2_GPIO_DIRECTION_OUT		1
> +
> +static int dln2_gpio_request(struct gpio_chip *chip, unsigned offset)
> +{
> +	struct dln2_gpio *dln2 = container_of(chip, struct dln2_gpio, gpio);
> +	struct dln2_gpio_pin req = {
> +		.pin = cpu_to_le16(offset),
> +	};
> +	struct dln2_gpio_pin_val rsp;
> +	int len = sizeof(rsp);
> +	int ret;
> +
> +	ret = dln2_gpio_pin_cmd(dln2, DLN2_GPIO_PIN_ENABLE, offset);
> +	if (ret < 0)
> +		return ret;
> +
> +	/* cache the pin direction */
> +	ret = dln2_transfer(dln2->pdev, DLN2_GPIO_PIN_GET_DIRECTION,
> +			    &req, sizeof(req), &rsp, &len);
> +	if (ret < 0)
> +		return ret;
> +	if (len < sizeof(rsp) || req.pin != rsp.pin)
> +		return -EPROTO;

Disable the pin?

> +
> +	switch (rsp.value) {
> +	case DLN2_GPIO_DIRECTION_IN:
> +		clear_bit(offset, dln2->pin_dir);
> +		return 0;
> +	case DLN2_GPIO_DIRECTION_OUT:
> +		set_bit(offset, dln2->pin_dir);
> +		return 0;
> +	default:
> +		return -EPROTO;

Disable the pin?

> +	}
> +}

[...]

> +static struct platform_driver dln2_gpio_driver = {
> +	.driver.name	= "dln2-gpio",
> +	.driver.owner	= THIS_MODULE,

No need to set the owner field when using the module_platform_driver
macro.

> +	.probe		= dln2_gpio_probe,
> +	.remove		= dln2_gpio_remove,
> +};
> +
> +module_platform_driver(dln2_gpio_driver);
> +
> +MODULE_AUTHOR("Daniel Baluta <daniel.baluta@...el.com");
> +MODULE_DESCRIPTION("Driver for the Diolan DLN2 GPIO interface");
> +MODULE_LICENSE("GPL v2");
> +MODULE_ALIAS("platform:dln2-gpio");

Johan
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