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e4k: add dc offset calibration code

This commit is contained in:
Harald Welte 2012-03-05 18:24:28 +01:00
parent 5a23c52120
commit c4c7c6add5
2 changed files with 78 additions and 0 deletions
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3
firmware/include/tuner_e4k.h
View File

@ -205,4 +205,7 @@ int sam3u_e4k_init(struct e4k_state *e4k, void *i2c, uint8_t slave_addr);
void sam3u_e4k_power(struct e4k_state *e4k, int on);
void sam3u_e4k_stby(struct e4k_state *e4k, int on);
int e4k_dc_offset_calibrate(struct e4k_state *e4k);
int e4k_dc_offset_gen_table(struct e4k_state *e4k);
#endif /* _E4K_TUNER_H */

75
firmware/src/tuner_e4k.c
View File

@ -684,6 +684,79 @@ int e4k_if_gain_set(struct e4k_state *e4k, uint8_t stage, int8_t value)
return e4k_reg_set_mask(e4k, field->reg, mask, rc << field->shift);
}
/***********************************************************************
* DC Offset */
/*! \brief Perform a DC offset calibration right now
* \param[e4k] handle to the tuner chip
*/
int e4k_dc_offset_calibrate(struct e4k_state *e4k)
{
/* make sure the DC range detector is enabled */
e4k_reg_set_mask(e4k, E4K_REG_DC5, E4K_DC5_RANGE_DET_EN, E4K_DC5_RANGE_DET_EN);
return e4k_reg_write(e4k, E4K_REG_DC1, 0x01);
}
static const int8_t if_gains_max[] = {
0, 6, 9, 9, 2, 15, 15
};
struct gain_comb {
int8_t mixer_gain;
uint8_t if1_gain;
uint8_t reg;
};
static const struct gain_comb dc_gain_comb[] = {
{ 0, -3, 0x50 },
{ 0, 6, 0x51 },
{ 12, -3, 0x52 },
{ 12, 6, 0x53 },
};
#define TO_LUT(offset, range) (offset | (range << 6))
int e4k_dc_offset_gen_table(struct e4k_state *e4k)
{
int i;
/* FIXME: read ont current gain values and write them back
* before returning to the caller */
/* set all 'other' gains to maximum */
for (i = 2; i <= 6; i++)
e4k_if_gain_set(e4k, i, if_gains_max[i]);
/* iterate over all mixer + if_stage_1 gain combinations */
for (i = 0; i < ARRAY_SIZE(dc_gain_comb); i++) {
uint8_t offs_i, offs_q, range_i, range_q;
/* set the combination of mixer / if1 gain */
e3k_mixer_gain_set(e4k, dc_gain_comb[i].mixer_gain);
e4k_if_gain_set(e4k, 1, dc_gain_comb[i].if1_gain);
/* perform actual calibration */
e4k_dc_offset_calibrate(e4k);
/* FIXME: do we have to wait? */
/* extract I/Q offset and range values */
offs_i = e4k_reg_read(e4k, E4K_REG_DC2) & 0x3F;
offs_q = e4k_reg_read(e4k, E4K_REG_DC3) & 0x3F;
range_i = e4k_reg_read(e4k, E4K_REG_DC4) & 0x3;
range_q = (e4k_reg_read(e4k, E4K_REG_DC4) >> 4) & 0x3;
/* write into the table */
e4k_reg_write(e4k, dc_gain_comb[i].reg,
TO_LUT(offs_q, range_q));
e4k_reg_write(e4k, dc_gain_comb[i].reg+0x10,
TO_LUT(offs_i, range_i));
}
return 0;
}
/***********************************************************************
* Initialization */
@ -697,6 +770,8 @@ static int magic_init(struct e4k_state *e4k)
e4k_reg_write(e4k, 0x88, 0x01);
e4k_reg_write(e4k, 0x9f, 0x7f);
e4k_reg_write(e4k, 0xa0, 0x07);
return 0;
}
/*! \brief Initialize the E4K tuner