drivers/i2c/busses/i2c-digicolor.c

File Facts

System

Linux kernel

Corpus path

drivers/i2c/busses/i2c-digicolor.c

Extension

.c

Size

8046 bytes

Lines

377

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.

• 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.
• Uses kernel synchronization; read lock ordering, sleepability, and interrupt context assumptions before translating.
• Touches IRQ or DMA behavior; this matters for the representative real-device path.
• Allocates kernel memory; connect allocation flags and lifetime to context constraints.
• Defines or uses C structs; map object ownership, embedded links, reference counts, and lock ownership.

Dependency Surface

• linux/clk.h
• linux/completion.h
• linux/delay.h
• linux/i2c.h
• linux/interrupt.h
• linux/io.h
• linux/kernel.h
• linux/module.h
• linux/of.h
• linux/platform_device.h

Detected Declarations

• struct dc_i2c
• function dc_i2c_cmd
• function dc_i2c_addr_cmd
• function dc_i2c_data
• function dc_i2c_write_byte
• function dc_i2c_write_buf
• function dc_i2c_next_read
• function dc_i2c_stop
• function dc_i2c_read_byte
• function dc_i2c_read_buf
• function dc_i2c_set_irq
• function dc_i2c_cmd_status
• function dc_i2c_start_msg
• function dc_i2c_irq
• function dc_i2c_xfer_msg
• function dc_i2c_xfer
• function dc_i2c_init_hw
• function dc_i2c_func
• function dc_i2c_probe
• function dc_i2c_remove

Annotated Snippet

struct dc_i2c {
	struct i2c_adapter	adap;
	struct device		*dev;
	void __iomem		*regs;
	struct clk		*clk;
	unsigned int		frequency;

	struct i2c_msg		*msg;
	unsigned int		msgbuf_ptr;
	int			last;
	spinlock_t		lock;
	struct completion	done;
	int			state;
	int			error;
};

enum {
	STATE_IDLE,
	STATE_START,
	STATE_ADDR,
	STATE_WRITE,
	STATE_READ,
	STATE_STOP,
};

static void dc_i2c_cmd(struct dc_i2c *i2c, u8 cmd)
{
	writeb_relaxed(cmd | II_COMMAND_GO, i2c->regs + II_COMMAND);
}

static u8 dc_i2c_addr_cmd(struct i2c_msg *msg)
{
	u8 addr = (msg->addr & 0x7f) << 1;

	if (msg->flags & I2C_M_RD)
		addr |= 1;

	return addr;
}

static void dc_i2c_data(struct dc_i2c *i2c, u8 data)
{
	writeb_relaxed(data, i2c->regs + II_DATA);
}

static void dc_i2c_write_byte(struct dc_i2c *i2c, u8 byte)
{
	dc_i2c_data(i2c, byte);
	dc_i2c_cmd(i2c, II_CMD_SEND_ACK);
}

static void dc_i2c_write_buf(struct dc_i2c *i2c)
{
	dc_i2c_write_byte(i2c, i2c->msg->buf[i2c->msgbuf_ptr++]);
}

static void dc_i2c_next_read(struct dc_i2c *i2c)
{
	bool last = (i2c->msgbuf_ptr + 1 == i2c->msg->len);

	dc_i2c_cmd(i2c, last ? II_CMD_GET_NOACK : II_CMD_GET_ACK);
}

static void dc_i2c_stop(struct dc_i2c *i2c)
{
	i2c->state = STATE_STOP;
	if (i2c->last)
		dc_i2c_cmd(i2c, II_CMD_STOP);
	else
		complete(&i2c->done);
}

static u8 dc_i2c_read_byte(struct dc_i2c *i2c)
{
	return readb_relaxed(i2c->regs + II_DATA);
}

static void dc_i2c_read_buf(struct dc_i2c *i2c)
{
	i2c->msg->buf[i2c->msgbuf_ptr++] = dc_i2c_read_byte(i2c);
	dc_i2c_next_read(i2c);
}

static void dc_i2c_set_irq(struct dc_i2c *i2c, int enable)
{
	if (enable)
		writeb_relaxed(1, i2c->regs + II_INTFLAG_CLEAR);
	writeb_relaxed(!!enable, i2c->regs + II_INTENABLE);
}

Annotation

• Immediate include surface: `linux/clk.h`, `linux/completion.h`, `linux/delay.h`, `linux/i2c.h`, `linux/interrupt.h`, `linux/io.h`, `linux/kernel.h`, `linux/module.h`.
• Detected declarations: `struct dc_i2c`, `function dc_i2c_cmd`, `function dc_i2c_addr_cmd`, `function dc_i2c_data`, `function dc_i2c_write_byte`, `function dc_i2c_write_buf`, `function dc_i2c_next_read`, `function dc_i2c_stop`, `function dc_i2c_read_byte`, `function dc_i2c_read_buf`.
• Atlas domain: Driver Families / drivers/i2c.
• Implementation status: source implementation candidate.
• Synchronization appears in or near this file; preserve lock ordering, sleepability, and interrupt-context constraints.
• IRQ or DMA behavior appears here, which is relevant to the selected PCIe/NVMe device path.

Implementation Notes

• This generated page is the file-by-file coverage layer; curated subsystem chapters should link here when they synthesize a multi-file control flow.
• Core OS pages should be promoted from atlas-only to deep-reviewed when they explain data structures, invariants, locking, lifecycle, and C implementation snippets.
• Driver-family pages are intentionally pattern-oriented unless they are part of the selected PCIe/NVMe representative device path.