drivers/i2c/muxes/i2c-mux-reg.c

Source file repositories/reference/linux-study-clean/drivers/i2c/muxes/i2c-mux-reg.c

File Facts

System
Linux kernel
Corpus path
drivers/i2c/muxes/i2c-mux-reg.c
Extension
.c
Size
5996 bytes
Lines
249
Domain
Driver Families
Bucket
drivers/i2c
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 regmux {
	struct i2c_mux_reg_platform_data data;
};

static int i2c_mux_reg_set(const struct regmux *mux, unsigned int chan_id)
{
	if (!mux->data.reg)
		return -EINVAL;

	/*
	 * Write to the register, followed by a read to ensure the write is
	 * completed on a "posted" bus, for example PCI or write buffers.
	 * The endianness of reading doesn't matter and the return data
	 * is not used.
	 */
	switch (mux->data.reg_size) {
	case 4:
		if (mux->data.little_endian)
			iowrite32(chan_id, mux->data.reg);
		else
			iowrite32be(chan_id, mux->data.reg);
		if (!mux->data.write_only)
			ioread32(mux->data.reg);
		break;
	case 2:
		if (mux->data.little_endian)
			iowrite16(chan_id, mux->data.reg);
		else
			iowrite16be(chan_id, mux->data.reg);
		if (!mux->data.write_only)
			ioread16(mux->data.reg);
		break;
	case 1:
		iowrite8(chan_id, mux->data.reg);
		if (!mux->data.write_only)
			ioread8(mux->data.reg);
		break;
	}

	return 0;
}

static int i2c_mux_reg_select(struct i2c_mux_core *muxc, u32 chan)
{
	struct regmux *mux = i2c_mux_priv(muxc);

	return i2c_mux_reg_set(mux, chan);
}

static int i2c_mux_reg_deselect(struct i2c_mux_core *muxc, u32 chan)
{
	struct regmux *mux = i2c_mux_priv(muxc);

	if (mux->data.idle_in_use)
		return i2c_mux_reg_set(mux, mux->data.idle);

	return 0;
}

static int i2c_mux_reg_probe_fw(struct regmux *mux, struct device *dev)
{
	struct fwnode_handle *fwnode, *child;
	struct i2c_adapter *adapter;
	unsigned *values;
	int ret, i = 0;

	if (!dev_fwnode(dev))
		return -ENODEV;

	fwnode = fwnode_find_reference(dev_fwnode(dev), "i2c-parent", 0);
	if (IS_ERR(fwnode)) {
		dev_err(dev, "missing 'i2c-parent' property\n");
		return -ENODEV;
	}

	adapter = i2c_find_adapter_by_fwnode(fwnode);
	fwnode_handle_put(fwnode);
	if (!adapter)
		return -EPROBE_DEFER;

	mux->data.parent = i2c_adapter_id(adapter);
	put_device(&adapter->dev);

	mux->data.n_values = device_get_child_node_count(dev);
	if (device_property_read_bool(dev, "little-endian")) {
		mux->data.little_endian = true;
	} else if (device_property_read_bool(dev, "big-endian")) {
		mux->data.little_endian = false;
	} else {
#if defined(__BYTE_ORDER) ? __BYTE_ORDER == __LITTLE_ENDIAN : \

Annotation

Implementation Notes