drivers/media/i2c/tw9906.c

Source file repositories/reference/linux-study-clean/drivers/media/i2c/tw9906.c

File Facts

System
Linux kernel
Corpus path
drivers/media/i2c/tw9906.c
Extension
.c
Size
5213 bytes
Lines
231
Domain
Driver Families
Bucket
drivers/media
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 tw9906 {
	struct v4l2_subdev sd;
	struct v4l2_ctrl_handler hdl;
	v4l2_std_id norm;
};

static inline struct tw9906 *to_state(struct v4l2_subdev *sd)
{
	return container_of(sd, struct tw9906, sd);
}

static const u8 initial_registers[] = {
	0x02, 0x40, /* input 0, composite */
	0x03, 0xa2, /* correct digital format */
	0x05, 0x81, /* or 0x01 for PAL */
	0x07, 0x02, /* window */
	0x08, 0x14, /* window */
	0x09, 0xf0, /* window */
	0x0a, 0x10, /* window */
	0x0b, 0xd0, /* window */
	0x0d, 0x00, /* scaling */
	0x0e, 0x11, /* scaling */
	0x0f, 0x00, /* scaling */
	0x10, 0x00, /* brightness */
	0x11, 0x60, /* contrast */
	0x12, 0x11, /* sharpness */
	0x13, 0x7e, /* U gain */
	0x14, 0x7e, /* V gain */
	0x15, 0x00, /* hue */
	0x19, 0x57, /* vbi */
	0x1a, 0x0f,
	0x1b, 0x40,
	0x29, 0x03,
	0x55, 0x00,
	0x6b, 0x26,
	0x6c, 0x36,
	0x6d, 0xf0,
	0x6e, 0x41,
	0x6f, 0x13,
	0xad, 0x70,
	0x00, 0x00, /* Terminator (reg 0x00 is read-only) */
};

static int write_reg(struct v4l2_subdev *sd, u8 reg, u8 value)
{
	struct i2c_client *client = v4l2_get_subdevdata(sd);

	return i2c_smbus_write_byte_data(client, reg, value);
}

static int write_regs(struct v4l2_subdev *sd, const u8 *regs)
{
	int i;

	for (i = 0; regs[i] != 0x00; i += 2)
		if (write_reg(sd, regs[i], regs[i + 1]) < 0)
			return -1;
	return 0;
}

static int tw9906_s_video_routing(struct v4l2_subdev *sd, u32 input,
				      u32 output, u32 config)
{
	write_reg(sd, 0x02, 0x40 | (input << 1));
	return 0;
}

static int tw9906_s_std(struct v4l2_subdev *sd, v4l2_std_id norm)
{
	struct tw9906 *dec = to_state(sd);
	bool is_60hz = norm & V4L2_STD_525_60;
	static const u8 config_60hz[] = {
		0x05, 0x81,
		0x07, 0x02,
		0x08, 0x14,
		0x09, 0xf0,
		0,    0,
	};
	static const u8 config_50hz[] = {
		0x05, 0x01,
		0x07, 0x12,
		0x08, 0x18,
		0x09, 0x20,
		0,    0,
	};

	write_regs(sd, is_60hz ? config_60hz : config_50hz);
	dec->norm = norm;
	return 0;
}

Annotation

Implementation Notes