drivers/media/dvb-frontends/tda8261.c

Source file repositories/reference/linux-study-clean/drivers/media/dvb-frontends/tda8261.c

File Facts

System
Linux kernel
Corpus path
drivers/media/dvb-frontends/tda8261.c
Extension
.c
Size
4686 bytes
Lines
196
Domain
Driver Families
Bucket
drivers/media
Inferred role
Driver Families: exported/initcall integration point
Status
integration 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 tda8261_state {
	struct dvb_frontend		*fe;
	struct i2c_adapter		*i2c;
	const struct tda8261_config	*config;

	/* state cache */
	u32 frequency;
	u32 bandwidth;
};

static int tda8261_read(struct tda8261_state *state, u8 *buf)
{
	const struct tda8261_config *config = state->config;
	int err = 0;
	struct i2c_msg msg = { .addr	= config->addr, .flags = I2C_M_RD,.buf = buf,  .len = 1 };

	if ((err = i2c_transfer(state->i2c, &msg, 1)) != 1)
		pr_err("%s: read error, err=%d\n", __func__, err);

	return err;
}

static int tda8261_write(struct tda8261_state *state, u8 *buf)
{
	const struct tda8261_config *config = state->config;
	int err = 0;
	struct i2c_msg msg = { .addr = config->addr, .flags = 0, .buf = buf, .len = 4 };

	if ((err = i2c_transfer(state->i2c, &msg, 1)) != 1)
		pr_err("%s: write error, err=%d\n", __func__, err);

	return err;
}

static int tda8261_get_status(struct dvb_frontend *fe, u32 *status)
{
	struct tda8261_state *state = fe->tuner_priv;
	u8 result = 0;
	int err = 0;

	*status = 0;

	if ((err = tda8261_read(state, &result)) < 0) {
		pr_err("%s: I/O Error\n", __func__);
		return err;
	}
	if ((result >> 6) & 0x01) {
		pr_debug("%s: Tuner Phase Locked\n", __func__);
		*status = 1;
	}

	return err;
}

static const u32 div_tab[] = { 2000, 1000,  500,  250,  125 }; /* kHz */
static const u8  ref_div[] = { 0x00, 0x01, 0x02, 0x05, 0x07 };

static int tda8261_get_frequency(struct dvb_frontend *fe, u32 *frequency)
{
	struct tda8261_state *state = fe->tuner_priv;

	*frequency = state->frequency;

	return 0;
}

static int tda8261_set_params(struct dvb_frontend *fe)
{
	struct dtv_frontend_properties *c = &fe->dtv_property_cache;
	struct tda8261_state *state = fe->tuner_priv;
	const struct tda8261_config *config = state->config;
	u32 frequency, N, status = 0;
	u8 buf[4];
	int err = 0;

	/*
	 * N = Max VCO Frequency / Channel Spacing
	 * Max VCO Frequency = VCO frequency + (channel spacing - 1)
	 * (to account for half channel spacing on either side)
	 */
	frequency = c->frequency;
	if ((frequency < 950000) || (frequency > 2150000)) {
		pr_warn("%s: Frequency beyond limits, frequency=%d\n",
			__func__, frequency);
		return -EINVAL;
	}
	N = (frequency + (div_tab[config->step_size] - 1)) / div_tab[config->step_size];
	pr_debug("%s: Step size=%d, Divider=%d, PG=0x%02x (%d)\n",
		__func__, config->step_size, div_tab[config->step_size], N, N);

Annotation

Implementation Notes