[PATCH v2 2/2] gpio: add driver for stmpe io-expander

[Sascha Hauer]

On Mon, Sep 03, 2012 at 01:03:47PM +0200, Steffen Trumtrar wrote:
> Signed-off-by: Steffen Trumtrar <s.trumtrar at pengutronix.de>
> ---
> +static int stmpe_gpio_direction_input(struct gpio_chip *chip, unsigned gpio)
> +{
> +	struct stmpe_gpio_chip *stmpegpio = container_of(chip, struct stmpe_gpio_chip, chip);
> +	struct stmpe_client_info *ci = (struct stmpe_client_info *)stmpegpio->ci;
> +	int ret;
> +	u8 val;
> +
> +	ci->read_reg(ci->stmpe, GPIO_SET_DIR + OFFSET(gpio), &val);
> +	val &= ~(1 << (gpio % 8));
> +	ret = ci->write_reg(ci->stmpe, GPIO_SET_DIR + OFFSET(gpio), val);
> +
> +	if (ret)
> +		dev_err(chip->dev, "couldn't change direction. Write failed!\n");
> +
> +	return 0;

Please propagate the error value.

> +}
> +
> +static int stmpe_gpio_direction_output(struct gpio_chip *chip, unsigned gpio, int value)
> +{
> +	struct stmpe_gpio_chip *stmpegpio = container_of(chip, struct stmpe_gpio_chip, chip);
> +	struct stmpe_client_info *ci = (struct stmpe_client_info *)stmpegpio->ci;
> +	int ret;
> +	u8 val;
> +
> +	ci->read_reg(ci->stmpe, GPIO_SET_DIR + OFFSET(gpio), &val);
> +	val |= 1 << (gpio % 8);
> +	ret = ci->write_reg(ci->stmpe, GPIO_SET_DIR + OFFSET(gpio), val);
> +
> +	stmpe_gpio_set_value(chip, gpio, value);
> +
> +	if (ret)
> +		dev_err(chip->dev, "couldn't change direction. Write failed!\n");
> +
> +	return 0;

ditto

> +
> +static int stmpe_gpio_probe(struct device_d *dev)
> +{
> +	struct stmpe_gpio_chip *stmpegpio;
> +	struct stmpe_client_info *ci;
> +
> +	stmpegpio = xzalloc(sizeof(*stmpegpio));
> +
> +	stmpegpio->base = dev_request_mem_region(dev, 0);
> +	stmpegpio->chip.ops = &stmpe_gpio_ops;
> +	stmpegpio->ci = dev->platform_data;
> +
> +	ci = (struct stmpe_client_info *)stmpegpio->ci;
> +
> +	if (ci->stmpe->pdata->gpio_base)
> +		stmpegpio->chip.base = ci->stmpe->pdata->gpio_base;
> +	else
> +		stmpegpio->chip.base = -1;
> +
> +	stmpegpio->chip.ngpio = 16;
> +	stmpegpio->chip.dev = dev;
> +
> +	gpiochip_add(&stmpegpio->chip);

It's worth checking the return value of gpiochip_add. It could indicate
that the selected chip.base is busy.

Sascha

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