drivers/mux/gpio.c

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

File Facts

System
Linux kernel
Corpus path
drivers/mux/gpio.c
Extension
.c
Size
2712 bytes
Lines
110
Domain
Driver Families
Bucket
drivers/mux
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 mux_gpio {
	struct gpio_descs *gpios;
};

static int mux_gpio_set(struct mux_control *mux, int state)
{
	struct mux_gpio *mux_gpio = mux_chip_priv(mux->chip);
	DECLARE_BITMAP(values, BITS_PER_TYPE(state));
	u32 value = state;

	bitmap_from_arr32(values, &value, BITS_PER_TYPE(value));

	gpiod_multi_set_value_cansleep(mux_gpio->gpios, values);

	return 0;
}

static const struct mux_control_ops mux_gpio_ops = {
	.set = mux_gpio_set,
};

static const struct of_device_id mux_gpio_dt_ids[] = {
	{ .compatible = "gpio-mux", },
	{ /* sentinel */ }
};
MODULE_DEVICE_TABLE(of, mux_gpio_dt_ids);

static int mux_gpio_probe(struct platform_device *pdev)
{
	struct device *dev = &pdev->dev;
	struct mux_chip *mux_chip;
	struct mux_gpio *mux_gpio;
	int pins;
	s32 idle_state;
	int ret;

	pins = gpiod_count(dev, "mux");
	if (pins < 0)
		return pins;

	mux_chip = devm_mux_chip_alloc(dev, 1, sizeof(*mux_gpio));
	if (IS_ERR(mux_chip))
		return PTR_ERR(mux_chip);

	mux_gpio = mux_chip_priv(mux_chip);
	mux_chip->ops = &mux_gpio_ops;

	mux_gpio->gpios = devm_gpiod_get_array(dev, "mux", GPIOD_OUT_LOW);
	if (IS_ERR(mux_gpio->gpios))
		return dev_err_probe(dev, PTR_ERR(mux_gpio->gpios),
				     "failed to get gpios\n");
	WARN_ON(pins != mux_gpio->gpios->ndescs);
	mux_chip->mux->states = BIT(pins);

	ret = device_property_read_u32(dev, "idle-state", (u32 *)&idle_state);
	if (ret >= 0 && idle_state != MUX_IDLE_AS_IS) {
		if (idle_state < 0 || idle_state >= mux_chip->mux->states) {
			dev_err(dev, "invalid idle-state %u\n", idle_state);
			return -EINVAL;
		}

		mux_chip->mux->idle_state = idle_state;
	}

	ret = devm_regulator_get_enable_optional(dev, "mux");
	if (ret && ret != -ENODEV)
		return dev_err_probe(dev, ret, "failed to get/enable mux supply\n");

	ret = devm_mux_chip_register(dev, mux_chip);
	if (ret < 0)
		return ret;

	dev_info(dev, "%u-way mux-controller registered\n",
		 mux_chip->mux->states);

	return 0;
}

static struct platform_driver mux_gpio_driver = {
	.driver = {
		.name = "gpio-mux",
		.of_match_table	= mux_gpio_dt_ids,
	},
	.probe = mux_gpio_probe,
};
module_platform_driver(mux_gpio_driver);

MODULE_DESCRIPTION("GPIO-controlled multiplexer driver");
MODULE_AUTHOR("Peter Rosin <peda@axentia.se>");
MODULE_LICENSE("GPL v2");

Annotation

Implementation Notes