drivers/gpio/gpio-pisosr.c

Source file repositories/reference/linux-study-clean/drivers/gpio/gpio-pisosr.c

File Facts

System
Linux kernel
Corpus path
drivers/gpio/gpio-pisosr.c
Extension
.c
Size
4272 bytes
Lines
175
Domain
Driver Families
Bucket
drivers/gpio
Inferred role
Driver Families: implementation source
Status
source implementation candidate

Why This File Exists

Repeatable hardware-adapter layer. Deep compatibility for every driver is out of scope; this atlas records patterns, probe lifecycles, bus glue, IRQ/DMA usage, and links back to core abstractions.

Dependency Surface

Detected Declarations

Annotated Snippet

struct pisosr_gpio {
	struct gpio_chip chip;
	struct spi_device *spi;
	u8 *buffer;
	size_t buffer_size;
	struct gpio_desc *load_gpio;
	struct mutex lock;
};

static int pisosr_gpio_refresh(struct pisosr_gpio *gpio)
{
	int ret;

	mutex_lock(&gpio->lock);

	if (gpio->load_gpio) {
		gpiod_set_value_cansleep(gpio->load_gpio, 1);
		udelay(1); /* registers load time (~10ns) */
		gpiod_set_value_cansleep(gpio->load_gpio, 0);
		udelay(1); /* registers recovery time (~5ns) */
	}

	ret = spi_read(gpio->spi, gpio->buffer, gpio->buffer_size);

	mutex_unlock(&gpio->lock);

	return ret;
}

static int pisosr_gpio_get_direction(struct gpio_chip *chip,
				     unsigned offset)
{
	/* This device always input */
	return GPIO_LINE_DIRECTION_IN;
}

static int pisosr_gpio_direction_input(struct gpio_chip *chip,
				       unsigned offset)
{
	/* This device always input */
	return 0;
}

static int pisosr_gpio_get(struct gpio_chip *chip, unsigned offset)
{
	struct pisosr_gpio *gpio = gpiochip_get_data(chip);

	/* Refresh may not always be needed */
	pisosr_gpio_refresh(gpio);

	return (gpio->buffer[offset / 8] >> (offset % 8)) & 0x1;
}

static int pisosr_gpio_get_multiple(struct gpio_chip *chip,
				    unsigned long *mask, unsigned long *bits)
{
	struct pisosr_gpio *gpio = gpiochip_get_data(chip);
	unsigned long offset;
	unsigned long gpio_mask;
	unsigned long buffer_state;

	pisosr_gpio_refresh(gpio);

	bitmap_zero(bits, chip->ngpio);
	for_each_set_clump8(offset, gpio_mask, mask, chip->ngpio) {
		buffer_state = gpio->buffer[offset / 8] & gpio_mask;
		bitmap_set_value8(bits, buffer_state, offset);
	}

	return 0;
}

static const struct gpio_chip template_chip = {
	.label			= "pisosr-gpio",
	.owner			= THIS_MODULE,
	.get_direction		= pisosr_gpio_get_direction,
	.direction_input	= pisosr_gpio_direction_input,
	.get			= pisosr_gpio_get,
	.get_multiple		= pisosr_gpio_get_multiple,
	.base			= -1,
	.ngpio			= DEFAULT_NGPIO,
	.can_sleep		= true,
};

static int pisosr_gpio_probe(struct spi_device *spi)
{
	struct device *dev = &spi->dev;
	struct pisosr_gpio *gpio;
	int ret;

Annotation

Implementation Notes