drivers/i2c/busses/i2c-dln2.c

Source file repositories/reference/linux-study-clean/drivers/i2c/busses/i2c-dln2.c

File Facts

System
Linux kernel
Corpus path
drivers/i2c/busses/i2c-dln2.c
Extension
.c
Size
6141 bytes
Lines
257
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 dln2_i2c {
	struct platform_device *pdev;
	struct i2c_adapter adapter;
	u8 port;
	/*
	 * Buffer to hold the packet for read or write transfers. One is enough
	 * since we can't have multiple transfers in parallel on the i2c bus.
	 */
	void *buf;
};

static int dln2_i2c_enable(struct dln2_i2c *dln2, bool enable)
{
	u16 cmd;
	struct {
		u8 port;
	} tx;

	tx.port = dln2->port;

	if (enable)
		cmd = DLN2_I2C_ENABLE;
	else
		cmd = DLN2_I2C_DISABLE;

	return dln2_transfer_tx(dln2->pdev, cmd, &tx, sizeof(tx));
}

static int dln2_i2c_write(struct dln2_i2c *dln2, u8 addr,
			  u8 *data, u16 data_len)
{
	int ret;
	struct {
		u8 port;
		u8 addr;
		u8 mem_addr_len;
		__le32 mem_addr;
		__le16 buf_len;
		u8 buf[DLN2_I2C_MAX_XFER_SIZE];
	} __packed *tx = dln2->buf;
	unsigned len;

	BUILD_BUG_ON(sizeof(*tx) > DLN2_I2C_BUF_SIZE);

	tx->port = dln2->port;
	tx->addr = addr;
	tx->mem_addr_len = 0;
	tx->mem_addr = 0;
	tx->buf_len = cpu_to_le16(data_len);
	memcpy(tx->buf, data, data_len);

	len = sizeof(*tx) + data_len - DLN2_I2C_MAX_XFER_SIZE;
	ret = dln2_transfer_tx(dln2->pdev, DLN2_I2C_WRITE, tx, len);
	if (ret < 0)
		return ret;

	return data_len;
}

static int dln2_i2c_read(struct dln2_i2c *dln2, u16 addr, u8 *data,
			 u16 data_len)
{
	int ret;
	struct {
		u8 port;
		u8 addr;
		u8 mem_addr_len;
		__le32 mem_addr;
		__le16 buf_len;
	} __packed tx;
	struct {
		__le16 buf_len;
		u8 buf[DLN2_I2C_MAX_XFER_SIZE];
	} __packed *rx = dln2->buf;
	unsigned rx_len = sizeof(*rx);

	BUILD_BUG_ON(sizeof(*rx) > DLN2_I2C_BUF_SIZE);

	tx.port = dln2->port;
	tx.addr = addr;
	tx.mem_addr_len = 0;
	tx.mem_addr = 0;
	tx.buf_len = cpu_to_le16(data_len);

	ret = dln2_transfer(dln2->pdev, DLN2_I2C_READ, &tx, sizeof(tx),
			    rx, &rx_len);
	if (ret < 0)
		return ret;
	if (rx_len < sizeof(rx->buf_len) + data_len)
		return -EPROTO;

Annotation

Implementation Notes