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FMC ADC 100M 14b 4cha - Software
Commit fc6f610b authored by Federico Vaga's avatar Federico Vaga
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drv: fix gain error on ADC 

Signed-off-by: Federico Vaga's avatarFederico Vaga <federico.vaga@cern.ch>
parent abb2cabe
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Showing with 39 additions and 9 deletions
kernel/fa-calibration.c
View file @ fc6f610b
......@@ -62,10 +62,36 @@ static void fa_calib_offset_set(struct fa_dev *fa, unsigned int chan, int val)
val & 0xFFFF /* prevent warning */);
}
static int fa_calib_adc_offset_fix(struct fa_dev *fa, int range, int offset,
uint32_t temperature)
/*
* Empirical values for the gain error slope
* 10V 0.0012500
* 1V -0.0000233
* 100mV -0.0000163
* To do integer math I store the value multiplied by 10000000
*/
static const int gain_adc_error_slope_fix[] = {
[FA100M14B4C_RANGE_10V] = 12500,
[FA100M14B4C_RANGE_1V] = -233,
[FA100M14B4C_RANGE_100mV] = -163,
};
/**
* Compute the correct gain
* @range: voltage range
* @gain_c: calibration value
* @delta_temp: temperature difference: (current temp. - calibration temp.)
* the unit must be milli-degree
*/
static int fa_calib_adc_gain_fix(int range, int gain_c, int32_t delta_temp)
{
return offset;
int error;
error = gain_adc_error_slope_fix[range] * delta_temp;
error /= 10000000; /* the slope was multiplied by 10000000 */
error /= 1000; /* the temperature is in milli-degree */
return gain_c - error;
}
static int fa_calib_adc_gain_fix(struct fa_dev *fa, int range, int gain,
......@@ -78,11 +104,11 @@ static void fa_calib_adc_config_chan(struct fa_dev *fa, unsigned int chan,
uint32_t temperature)
{
int range = fa->range[chan];
int offset = fa->calib.adc[range].offset[chan];
int gain = fa->calib.adc[range].gain[chan];
offset = fa_calib_adc_offset_fix(fa, range, offset, temperature);
gain = fa_calib_adc_gain_fix(fa, range, gain, temperature);
struct fa_calib_stanza *cal = &fa->calib.adc[range];
int32_t delta_temp = temperature - cal->temperature;
int offset = cal->offset[chan];
int gain = fa_calib_adc_gain_fix(range, cal->gain[chan],
delta_temp);
dev_dbg(&fa->pdev->dev, "%s: {chan: %d, range: %d, gain: 0x%x, offset: 0x%x}\n",
__func__, chan, range, gain, offset);
......@@ -98,8 +124,10 @@ int fa_calib_adc_config(struct fa_dev *fa)
temperature = fa_temperature_read(fa);
dev_dbg(&fa->pdev->dev, "%s: {temperature: %d}\n", __func__, temperature);
spin_lock(&fa->zdev->cset->lock);
for (i = 0; i < FA100M14B4C_NCHAN; ++i)
fa_calib_adc_config_chan(fa, i, temperature);
spin_unlock(&fa->zdev->cset->lock);
return fa_calib_apply(fa);
}
......
kernel/fa-core.c
View file @ fc6f610b
......@@ -274,7 +274,6 @@ int zfad_set_range(struct fa_dev *fa, struct zio_channel *chan,
range = FA100M14B4C_RANGE_1V;
else if (range >= FA100M14B4C_RANGE_10V_CAL)
range -= FA100M14B4C_RANGE_10V_CAL;
fa->range[chan->index] = range;
if (range < 0 || range > ARRAY_SIZE(fa->calib.adc)) {
dev_info(fa->msgdev, "Invalid range %i or ch %i\n",
......@@ -282,6 +281,9 @@ int zfad_set_range(struct fa_dev *fa, struct zio_channel *chan,
return -EINVAL;
}
spin_lock(&fa->zdev->cset->lock);
fa->range[chan->index] = range;
spin_unlock(&fa->zdev->cset->lock);
/* recalculate user offset for the new range */
zfad_apply_offset(chan);
return fa_calib_adc_config(fa);
......
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