mfd: Calibrate ab8500 gpadc using OTP values
The GPADC found in the AB8500 needs to be calibrated to work properly. This is done by writing a number of special OTP (one-time-programmable) registers at production. This patch makes sure that these values are used to calibrate the returned value from the GPADC so that it is correct. Signed-off-by: Johan Palsson <johan.palsson@stericsson.com> Signed-off-by: Linus Walleij <linus.walleij@linaro.org> Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>
This commit is contained in:
Johan Palsson
Samuel Ortiz
parent
633e0fa590
commit
586f3318ad
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@ -4,6 +4,7 @@
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* License Terms: GNU General Public License v2
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* Author: Arun R Murthy <arun.murthy@stericsson.com>
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* Author: Daniel Willerud <daniel.willerud@stericsson.com>
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* Author: Johan Palsson <johan.palsson@stericsson.com>
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*/
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#include <linux/init.h>
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#include <linux/module.h>
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@ -36,6 +37,18 @@
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#define AB8500_GPADC_AUTODATAH_REG 0x08
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#define AB8500_GPADC_MUX_CTRL_REG 0x09
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/*
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* OTP register offsets
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* Bank : 0x15
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*/
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#define AB8500_GPADC_CAL_1 0x0F
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#define AB8500_GPADC_CAL_2 0x10
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#define AB8500_GPADC_CAL_3 0x11
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#define AB8500_GPADC_CAL_4 0x12
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#define AB8500_GPADC_CAL_5 0x13
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#define AB8500_GPADC_CAL_6 0x14
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#define AB8500_GPADC_CAL_7 0x15
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/* gpadc constants */
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#define EN_VINTCORE12 0x04
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#define EN_VTVOUT 0x02
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@ -47,8 +60,46 @@
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#define DIS_ZERO 0x00
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#define GPADC_BUSY 0x01
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/* GPADC constants from AB8500 spec, UM0836 */
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#define ADC_RESOLUTION 1024
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#define ADC_CH_BTEMP_MIN 0
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#define ADC_CH_BTEMP_MAX 1350
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#define ADC_CH_DIETEMP_MIN 0
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#define ADC_CH_DIETEMP_MAX 1350
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#define ADC_CH_CHG_V_MIN 0
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#define ADC_CH_CHG_V_MAX 20030
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#define ADC_CH_ACCDET2_MIN 0
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#define ADC_CH_ACCDET2_MAX 2500
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#define ADC_CH_VBAT_MIN 2300
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#define ADC_CH_VBAT_MAX 4800
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#define ADC_CH_CHG_I_MIN 0
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#define ADC_CH_CHG_I_MAX 1500
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#define ADC_CH_BKBAT_MIN 0
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#define ADC_CH_BKBAT_MAX 3200
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/* This is used to not lose precision when dividing to get gain and offset */
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#define CALIB_SCALE 1000
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enum cal_channels {
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ADC_INPUT_VMAIN = 0,
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ADC_INPUT_BTEMP,
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ADC_INPUT_VBAT,
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NBR_CAL_INPUTS,
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};
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/**
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* struct ab8500_gpadc - ab8500 GPADC device information
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* struct adc_cal_data - Table for storing gain and offset for the calibrated
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* ADC channels
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* @gain: Gain of the ADC channel
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* @offset: Offset of the ADC channel
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*/
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struct adc_cal_data {
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u64 gain;
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u64 offset;
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};
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/**
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* struct ab8500_gpadc - AB8500 GPADC device information
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* @dev: pointer to the struct device
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* @node: a list of AB8500 GPADCs, hence prepared for
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reentrance
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@ -57,6 +108,7 @@
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* @ab8500_gpadc_lock: structure of type mutex
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* @regu: pointer to the struct regulator
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* @irq: interrupt number that is used by gpadc
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* @cal_data array of ADC calibration data structs
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*/
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struct ab8500_gpadc {
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struct device *dev;
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@ -65,6 +117,7 @@ struct ab8500_gpadc {
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struct mutex ab8500_gpadc_lock;
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struct regulator *regu;
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int irq;
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struct adc_cal_data cal_data[NBR_CAL_INPUTS];
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};
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static LIST_HEAD(ab8500_gpadc_list);
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@ -86,13 +139,102 @@ struct ab8500_gpadc *ab8500_gpadc_get(char *name)
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}
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EXPORT_SYMBOL(ab8500_gpadc_get);
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static int ab8500_gpadc_ad_to_voltage(struct ab8500_gpadc *gpadc, u8 input,
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int ad_value)
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{
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int res;
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switch (input) {
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case MAIN_CHARGER_V:
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/* For some reason we don't have calibrated data */
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if (!gpadc->cal_data[ADC_INPUT_VMAIN].gain) {
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res = ADC_CH_CHG_V_MIN + (ADC_CH_CHG_V_MAX -
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ADC_CH_CHG_V_MIN) * ad_value /
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ADC_RESOLUTION;
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break;
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}
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/* Here we can use the calibrated data */
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res = (int) (ad_value * gpadc->cal_data[ADC_INPUT_VMAIN].gain +
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gpadc->cal_data[ADC_INPUT_VMAIN].offset) / CALIB_SCALE;
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break;
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case BAT_CTRL:
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case BTEMP_BALL:
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case ACC_DETECT1:
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case ADC_AUX1:
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case ADC_AUX2:
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/* For some reason we don't have calibrated data */
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if (!gpadc->cal_data[ADC_INPUT_BTEMP].gain) {
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res = ADC_CH_BTEMP_MIN + (ADC_CH_BTEMP_MAX -
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ADC_CH_BTEMP_MIN) * ad_value /
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ADC_RESOLUTION;
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break;
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}
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/* Here we can use the calibrated data */
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res = (int) (ad_value * gpadc->cal_data[ADC_INPUT_BTEMP].gain +
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gpadc->cal_data[ADC_INPUT_BTEMP].offset) / CALIB_SCALE;
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break;
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case MAIN_BAT_V:
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/* For some reason we don't have calibrated data */
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if (!gpadc->cal_data[ADC_INPUT_VBAT].gain) {
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res = ADC_CH_VBAT_MIN + (ADC_CH_VBAT_MAX -
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ADC_CH_VBAT_MIN) * ad_value /
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ADC_RESOLUTION;
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break;
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}
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/* Here we can use the calibrated data */
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res = (int) (ad_value * gpadc->cal_data[ADC_INPUT_VBAT].gain +
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gpadc->cal_data[ADC_INPUT_VBAT].offset) / CALIB_SCALE;
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break;
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case DIE_TEMP:
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res = ADC_CH_DIETEMP_MIN +
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(ADC_CH_DIETEMP_MAX - ADC_CH_DIETEMP_MIN) * ad_value /
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ADC_RESOLUTION;
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break;
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case ACC_DETECT2:
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res = ADC_CH_ACCDET2_MIN +
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(ADC_CH_ACCDET2_MAX - ADC_CH_ACCDET2_MIN) * ad_value /
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ADC_RESOLUTION;
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break;
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case VBUS_V:
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res = ADC_CH_CHG_V_MIN +
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(ADC_CH_CHG_V_MAX - ADC_CH_CHG_V_MIN) * ad_value /
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ADC_RESOLUTION;
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break;
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case MAIN_CHARGER_C:
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case USB_CHARGER_C:
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res = ADC_CH_CHG_I_MIN +
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(ADC_CH_CHG_I_MAX - ADC_CH_CHG_I_MIN) * ad_value /
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ADC_RESOLUTION;
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break;
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case BK_BAT_V:
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res = ADC_CH_BKBAT_MIN +
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(ADC_CH_BKBAT_MAX - ADC_CH_BKBAT_MIN) * ad_value /
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ADC_RESOLUTION;
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break;
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default:
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dev_err(gpadc->dev,
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"unknown channel, not possible to convert\n");
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res = -EINVAL;
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break;
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}
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return res;
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}
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/**
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* ab8500_gpadc_convert() - gpadc conversion
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* @input: analog input to be converted to digital data
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*
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* This function converts the selected analog i/p to digital
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* data. Thereafter calibration has to be made to obtain the
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* data in the required quantity measurement.
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* data.
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*/
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int ab8500_gpadc_convert(struct ab8500_gpadc *gpadc, u8 input)
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{
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@ -189,7 +331,8 @@ int ab8500_gpadc_convert(struct ab8500_gpadc *gpadc, u8 input)
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/* Disable VTVout LDO this is required for GPADC */
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regulator_disable(gpadc->regu);
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mutex_unlock(&gpadc->ab8500_gpadc_lock);
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return data;
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ret = ab8500_gpadc_ad_to_voltage(gpadc, input, data);
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return ret;
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out:
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/*
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@ -227,6 +370,138 @@ static irqreturn_t ab8500_bm_gpswadcconvend_handler(int irq, void *_gpadc)
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return IRQ_HANDLED;
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}
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static int otp_cal_regs[] = {
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AB8500_GPADC_CAL_1,
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AB8500_GPADC_CAL_2,
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AB8500_GPADC_CAL_3,
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AB8500_GPADC_CAL_4,
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AB8500_GPADC_CAL_5,
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AB8500_GPADC_CAL_6,
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AB8500_GPADC_CAL_7,
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};
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static void ab8500_gpadc_read_calibration_data(struct ab8500_gpadc *gpadc)
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{
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int i;
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int ret[ARRAY_SIZE(otp_cal_regs)];
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u8 gpadc_cal[ARRAY_SIZE(otp_cal_regs)];
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int vmain_high, vmain_low;
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int btemp_high, btemp_low;
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int vbat_high, vbat_low;
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/* First we read all OTP registers and store the error code */
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for (i = 0; i < ARRAY_SIZE(otp_cal_regs); i++) {
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ret[i] = abx500_get_register_interruptible(gpadc->dev,
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AB8500_OTP_EMUL, otp_cal_regs[i], &gpadc_cal[i]);
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if (ret[i] < 0)
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dev_err(gpadc->dev, "%s: read otp reg 0x%02x failed\n",
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__func__, otp_cal_regs[i]);
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}
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/*
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* The ADC calibration data is stored in OTP registers.
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* The layout of the calibration data is outlined below and a more
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* detailed description can be found in UM0836
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*
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* vm_h/l = vmain_high/low
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* bt_h/l = btemp_high/low
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* vb_h/l = vbat_high/low
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*
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* Data bits:
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* | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0
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* |.......|.......|.......|.......|.......|.......|.......|.......
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* | | vm_h9 | vm_h8
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* |.......|.......|.......|.......|.......|.......|.......|.......
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* | | vm_h7 | vm_h6 | vm_h5 | vm_h4 | vm_h3 | vm_h2
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* |.......|.......|.......|.......|.......|.......|.......|.......
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* | vm_h1 | vm_h0 | vm_l4 | vm_l3 | vm_l2 | vm_l1 | vm_l0 | bt_h9
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* |.......|.......|.......|.......|.......|.......|.......|.......
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* | bt_h8 | bt_h7 | bt_h6 | bt_h5 | bt_h4 | bt_h3 | bt_h2 | bt_h1
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* |.......|.......|.......|.......|.......|.......|.......|.......
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* | bt_h0 | bt_l4 | bt_l3 | bt_l2 | bt_l1 | bt_l0 | vb_h9 | vb_h8
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* |.......|.......|.......|.......|.......|.......|.......|.......
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* | vb_h7 | vb_h6 | vb_h5 | vb_h4 | vb_h3 | vb_h2 | vb_h1 | vb_h0
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* |.......|.......|.......|.......|.......|.......|.......|.......
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* | vb_l5 | vb_l4 | vb_l3 | vb_l2 | vb_l1 | vb_l0 |
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* |.......|.......|.......|.......|.......|.......|.......|.......
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*
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*
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* Ideal output ADC codes corresponding to injected input voltages
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* during manufacturing is:
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*
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* vmain_high: Vin = 19500mV / ADC ideal code = 997
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* vmain_low: Vin = 315mV / ADC ideal code = 16
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* btemp_high: Vin = 1300mV / ADC ideal code = 985
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* btemp_low: Vin = 21mV / ADC ideal code = 16
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* vbat_high: Vin = 4700mV / ADC ideal code = 982
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* vbat_low: Vin = 2380mV / ADC ideal code = 33
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*/
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/* Calculate gain and offset for VMAIN if all reads succeeded */
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if (!(ret[0] < 0 || ret[1] < 0 || ret[2] < 0)) {
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vmain_high = (((gpadc_cal[0] & 0x03) << 8) |
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((gpadc_cal[1] & 0x3F) << 2) |
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((gpadc_cal[2] & 0xC0) >> 6));
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vmain_low = ((gpadc_cal[2] & 0x3E) >> 1);
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gpadc->cal_data[ADC_INPUT_VMAIN].gain = CALIB_SCALE *
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(19500 - 315) / (vmain_high - vmain_low);
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gpadc->cal_data[ADC_INPUT_VMAIN].offset = CALIB_SCALE * 19500 -
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(CALIB_SCALE * (19500 - 315) /
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(vmain_high - vmain_low)) * vmain_high;
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} else {
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gpadc->cal_data[ADC_INPUT_VMAIN].gain = 0;
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}
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/* Calculate gain and offset for BTEMP if all reads succeeded */
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if (!(ret[2] < 0 || ret[3] < 0 || ret[4] < 0)) {
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btemp_high = (((gpadc_cal[2] & 0x01) << 9) |
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(gpadc_cal[3] << 1) |
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((gpadc_cal[4] & 0x80) >> 7));
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btemp_low = ((gpadc_cal[4] & 0x7C) >> 2);
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gpadc->cal_data[ADC_INPUT_BTEMP].gain =
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CALIB_SCALE * (1300 - 21) / (btemp_high - btemp_low);
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gpadc->cal_data[ADC_INPUT_BTEMP].offset = CALIB_SCALE * 1300 -
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(CALIB_SCALE * (1300 - 21) /
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(btemp_high - btemp_low)) * btemp_high;
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} else {
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gpadc->cal_data[ADC_INPUT_BTEMP].gain = 0;
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}
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/* Calculate gain and offset for VBAT if all reads succeeded */
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if (!(ret[4] < 0 || ret[5] < 0 || ret[6] < 0)) {
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vbat_high = (((gpadc_cal[4] & 0x03) << 8) | gpadc_cal[5]);
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vbat_low = ((gpadc_cal[6] & 0xFC) >> 2);
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gpadc->cal_data[ADC_INPUT_VBAT].gain = CALIB_SCALE *
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(4700 - 2380) / (vbat_high - vbat_low);
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gpadc->cal_data[ADC_INPUT_VBAT].offset = CALIB_SCALE * 4700 -
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(CALIB_SCALE * (4700 - 2380) /
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(vbat_high - vbat_low)) * vbat_high;
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} else {
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gpadc->cal_data[ADC_INPUT_VBAT].gain = 0;
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}
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dev_dbg(gpadc->dev, "VMAIN gain %llu offset %llu\n",
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gpadc->cal_data[ADC_INPUT_VMAIN].gain,
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gpadc->cal_data[ADC_INPUT_VMAIN].offset);
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dev_dbg(gpadc->dev, "BTEMP gain %llu offset %llu\n",
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gpadc->cal_data[ADC_INPUT_BTEMP].gain,
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gpadc->cal_data[ADC_INPUT_BTEMP].offset);
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dev_dbg(gpadc->dev, "VBAT gain %llu offset %llu\n",
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gpadc->cal_data[ADC_INPUT_VBAT].gain,
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gpadc->cal_data[ADC_INPUT_VBAT].offset);
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}
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static int __devinit ab8500_gpadc_probe(struct platform_device *pdev)
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{
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int ret = 0;
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@ -269,6 +544,7 @@ static int __devinit ab8500_gpadc_probe(struct platform_device *pdev)
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dev_err(gpadc->dev, "failed to get vtvout LDO\n");
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goto fail_irq;
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}
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ab8500_gpadc_read_calibration_data(gpadc);
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list_add_tail(&gpadc->node, &ab8500_gpadc_list);
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dev_dbg(gpadc->dev, "probe success\n");
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return 0;
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@ -318,6 +594,6 @@ subsys_initcall_sync(ab8500_gpadc_init);
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module_exit(ab8500_gpadc_exit);
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MODULE_LICENSE("GPL v2");
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MODULE_AUTHOR("Arun R Murthy, Daniel Willerud");
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MODULE_AUTHOR("Arun R Murthy, Daniel Willerud, Johan Palsson");
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MODULE_ALIAS("platform:ab8500_gpadc");
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MODULE_DESCRIPTION("AB8500 GPADC driver");
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