Commit 586f3318 authored by Johan Palsson's avatar Johan Palsson Committed by Samuel Ortiz
Browse files

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: default avatarJohan Palsson <johan.palsson@stericsson.com>
Signed-off-by: default avatarLinus Walleij <linus.walleij@linaro.org>
Signed-off-by: default avatarSamuel Ortiz <sameo@linux.intel.com>
parent 633e0fa5

drivers/mfd/ab8500-gpadc.c

+281 −5
Original line number Diff line number Diff line
@@ -4,6 +4,7 @@ 
 * License Terms: GNU General Public License v2

 * Author: Arun R Murthy <arun.murthy@stericsson.com>

 * Author: Daniel Willerud <daniel.willerud@stericsson.com>

 * Author: Johan Palsson <johan.palsson@stericsson.com>

 */

#include <linux/init.h>

#include <linux/module.h>
@@ -36,6 +37,18 @@ 
#define AB8500_GPADC_AUTODATAH_REG	0x08

#define AB8500_GPADC_MUX_CTRL_REG	0x09



/*

 * OTP register offsets

 * Bank : 0x15

 */

#define AB8500_GPADC_CAL_1		0x0F

#define AB8500_GPADC_CAL_2		0x10

#define AB8500_GPADC_CAL_3		0x11

#define AB8500_GPADC_CAL_4		0x12

#define AB8500_GPADC_CAL_5		0x13

#define AB8500_GPADC_CAL_6		0x14

#define AB8500_GPADC_CAL_7		0x15



/* gpadc constants */

#define EN_VINTCORE12			0x04

#define EN_VTVOUT			0x02
@@ -47,8 +60,46 @@ 
#define DIS_ZERO			0x00

#define GPADC_BUSY			0x01



/* GPADC constants from AB8500 spec, UM0836 */

#define ADC_RESOLUTION			1024

#define ADC_CH_BTEMP_MIN		0

#define ADC_CH_BTEMP_MAX		1350

#define ADC_CH_DIETEMP_MIN		0

#define ADC_CH_DIETEMP_MAX		1350

#define ADC_CH_CHG_V_MIN		0

#define ADC_CH_CHG_V_MAX		20030

#define ADC_CH_ACCDET2_MIN		0

#define ADC_CH_ACCDET2_MAX		2500

#define ADC_CH_VBAT_MIN			2300

#define ADC_CH_VBAT_MAX			4800

#define ADC_CH_CHG_I_MIN		0

#define ADC_CH_CHG_I_MAX		1500

#define ADC_CH_BKBAT_MIN		0

#define ADC_CH_BKBAT_MAX		3200



/* This is used to not lose precision when dividing to get gain and offset */

#define CALIB_SCALE			1000



enum cal_channels {

	ADC_INPUT_VMAIN = 0,

	ADC_INPUT_BTEMP,

	ADC_INPUT_VBAT,

	NBR_CAL_INPUTS,

};



/**

 * struct adc_cal_data - Table for storing gain and offset for the calibrated

 * ADC channels

 * @gain:		Gain of the ADC channel

 * @offset:		Offset of the ADC channel

 */

struct adc_cal_data {

	u64 gain;

	u64 offset;

};



/**

 * struct ab8500_gpadc - ab8500 GPADC device information

 * struct ab8500_gpadc - AB8500 GPADC device information

 * @dev:			pointer to the struct device

 * @node:			a list of AB8500 GPADCs, hence prepared for

				reentrance
@@ -57,6 +108,7 @@ 
 * @ab8500_gpadc_lock:		structure of type mutex

 * @regu:			pointer to the struct regulator

 * @irq:			interrupt number that is used by gpadc

 * @cal_data			array of ADC calibration data structs

 */

struct ab8500_gpadc {

	struct device *dev;
@@ -65,6 +117,7 @@ struct ab8500_gpadc { 
	struct mutex ab8500_gpadc_lock;

	struct regulator *regu;

	int irq;

	struct adc_cal_data cal_data[NBR_CAL_INPUTS];

};



static LIST_HEAD(ab8500_gpadc_list);
@@ -86,13 +139,102 @@ struct ab8500_gpadc *ab8500_gpadc_get(char *name) 
}

EXPORT_SYMBOL(ab8500_gpadc_get);



static int ab8500_gpadc_ad_to_voltage(struct ab8500_gpadc *gpadc, u8 input,

	int ad_value)

{

	int res;



	switch (input) {

	case MAIN_CHARGER_V:

		/* For some reason we don't have calibrated data */

		if (!gpadc->cal_data[ADC_INPUT_VMAIN].gain) {

			res = ADC_CH_CHG_V_MIN + (ADC_CH_CHG_V_MAX -

				ADC_CH_CHG_V_MIN) * ad_value /

				ADC_RESOLUTION;

			break;

		}

		/* Here we can use the calibrated data */

		res = (int) (ad_value * gpadc->cal_data[ADC_INPUT_VMAIN].gain +

			gpadc->cal_data[ADC_INPUT_VMAIN].offset) / CALIB_SCALE;

		break;



	case BAT_CTRL:

	case BTEMP_BALL:

	case ACC_DETECT1:

	case ADC_AUX1:

	case ADC_AUX2:

		/* For some reason we don't have calibrated data */

		if (!gpadc->cal_data[ADC_INPUT_BTEMP].gain) {

			res = ADC_CH_BTEMP_MIN + (ADC_CH_BTEMP_MAX -

				ADC_CH_BTEMP_MIN) * ad_value /

				ADC_RESOLUTION;

			break;

		}

		/* Here we can use the calibrated data */

		res = (int) (ad_value * gpadc->cal_data[ADC_INPUT_BTEMP].gain +

			gpadc->cal_data[ADC_INPUT_BTEMP].offset) / CALIB_SCALE;

		break;



	case MAIN_BAT_V:

		/* For some reason we don't have calibrated data */

		if (!gpadc->cal_data[ADC_INPUT_VBAT].gain) {

			res = ADC_CH_VBAT_MIN + (ADC_CH_VBAT_MAX -

				ADC_CH_VBAT_MIN) * ad_value /

				ADC_RESOLUTION;

			break;

		}

		/* Here we can use the calibrated data */

		res = (int) (ad_value * gpadc->cal_data[ADC_INPUT_VBAT].gain +

			gpadc->cal_data[ADC_INPUT_VBAT].offset) / CALIB_SCALE;

		break;



	case DIE_TEMP:

		res = ADC_CH_DIETEMP_MIN +

			(ADC_CH_DIETEMP_MAX - ADC_CH_DIETEMP_MIN) * ad_value /

			ADC_RESOLUTION;

		break;



	case ACC_DETECT2:

		res = ADC_CH_ACCDET2_MIN +

			(ADC_CH_ACCDET2_MAX - ADC_CH_ACCDET2_MIN) * ad_value /

			ADC_RESOLUTION;

		break;



	case VBUS_V:

		res = ADC_CH_CHG_V_MIN +

			(ADC_CH_CHG_V_MAX - ADC_CH_CHG_V_MIN) * ad_value /

			ADC_RESOLUTION;

		break;



	case MAIN_CHARGER_C:

	case USB_CHARGER_C:

		res = ADC_CH_CHG_I_MIN +

			(ADC_CH_CHG_I_MAX - ADC_CH_CHG_I_MIN) * ad_value /

			ADC_RESOLUTION;

		break;



	case BK_BAT_V:

		res = ADC_CH_BKBAT_MIN +

			(ADC_CH_BKBAT_MAX - ADC_CH_BKBAT_MIN) * ad_value /

			ADC_RESOLUTION;

		break;



	default:

		dev_err(gpadc->dev,

			"unknown channel, not possible to convert\n");

		res = -EINVAL;

		break;



	}

	return res;

}



/**

 * ab8500_gpadc_convert() - gpadc conversion

 * @input:	analog input to be converted to digital data

 *

 * This function converts the selected analog i/p to digital

 * data. Thereafter calibration has to be made to obtain the

 * data in the required quantity measurement.

 * data.

 */

int ab8500_gpadc_convert(struct ab8500_gpadc *gpadc, u8 input)

{
@@ -189,7 +331,8 @@ int ab8500_gpadc_convert(struct ab8500_gpadc *gpadc, u8 input) 
	/* Disable VTVout LDO this is required for GPADC */

	regulator_disable(gpadc->regu);

	mutex_unlock(&gpadc->ab8500_gpadc_lock);

	return data;

	ret = ab8500_gpadc_ad_to_voltage(gpadc, input, data);

	return ret;



out:

	/*
@@ -227,6 +370,138 @@ static irqreturn_t ab8500_bm_gpswadcconvend_handler(int irq, void *_gpadc) 
	return IRQ_HANDLED;

}



static int otp_cal_regs[] = {

	AB8500_GPADC_CAL_1,

	AB8500_GPADC_CAL_2,

	AB8500_GPADC_CAL_3,

	AB8500_GPADC_CAL_4,

	AB8500_GPADC_CAL_5,

	AB8500_GPADC_CAL_6,

	AB8500_GPADC_CAL_7,

};



static void ab8500_gpadc_read_calibration_data(struct ab8500_gpadc *gpadc)

{

	int i;

	int ret[ARRAY_SIZE(otp_cal_regs)];

	u8 gpadc_cal[ARRAY_SIZE(otp_cal_regs)];



	int vmain_high, vmain_low;

	int btemp_high, btemp_low;

	int vbat_high, vbat_low;



	/* First we read all OTP registers and store the error code */

	for (i = 0; i < ARRAY_SIZE(otp_cal_regs); i++) {

		ret[i] = abx500_get_register_interruptible(gpadc->dev,

			AB8500_OTP_EMUL, otp_cal_regs[i],  &gpadc_cal[i]);

		if (ret[i] < 0)

			dev_err(gpadc->dev, "%s: read otp reg 0x%02x failed\n",

				__func__, otp_cal_regs[i]);

	}



	/*

	 * The ADC calibration data is stored in OTP registers.

	 * The layout of the calibration data is outlined below and a more

	 * detailed description can be found in UM0836

	 *

	 * vm_h/l = vmain_high/low

	 * bt_h/l = btemp_high/low

	 * vb_h/l = vbat_high/low

	 *

	 * Data bits:

	 * | 7	   | 6	   | 5	   | 4	   | 3	   | 2	   | 1	   | 0

	 * |.......|.......|.......|.......|.......|.......|.......|.......

	 * |						   | vm_h9 | vm_h8

	 * |.......|.......|.......|.......|.......|.......|.......|.......

	 * |		   | vm_h7 | vm_h6 | vm_h5 | vm_h4 | vm_h3 | vm_h2

	 * |.......|.......|.......|.......|.......|.......|.......|.......

	 * | vm_h1 | vm_h0 | vm_l4 | vm_l3 | vm_l2 | vm_l1 | vm_l0 | bt_h9

	 * |.......|.......|.......|.......|.......|.......|.......|.......

	 * | bt_h8 | bt_h7 | bt_h6 | bt_h5 | bt_h4 | bt_h3 | bt_h2 | bt_h1

	 * |.......|.......|.......|.......|.......|.......|.......|.......

	 * | bt_h0 | bt_l4 | bt_l3 | bt_l2 | bt_l1 | bt_l0 | vb_h9 | vb_h8

	 * |.......|.......|.......|.......|.......|.......|.......|.......

	 * | vb_h7 | vb_h6 | vb_h5 | vb_h4 | vb_h3 | vb_h2 | vb_h1 | vb_h0

	 * |.......|.......|.......|.......|.......|.......|.......|.......

	 * | vb_l5 | vb_l4 | vb_l3 | vb_l2 | vb_l1 | vb_l0 |

	 * |.......|.......|.......|.......|.......|.......|.......|.......

	 *

	 *

	 * Ideal output ADC codes corresponding to injected input voltages

	 * during manufacturing is:

	 *

	 * vmain_high: Vin = 19500mV / ADC ideal code = 997

	 * vmain_low:  Vin = 315mV   / ADC ideal code = 16

	 * btemp_high: Vin = 1300mV  / ADC ideal code = 985

	 * btemp_low:  Vin = 21mV    / ADC ideal code = 16

	 * vbat_high:  Vin = 4700mV  / ADC ideal code = 982

	 * vbat_low:   Vin = 2380mV  / ADC ideal code = 33

	 */



	/* Calculate gain and offset for VMAIN if all reads succeeded */

	if (!(ret[0] < 0 || ret[1] < 0 || ret[2] < 0)) {

		vmain_high = (((gpadc_cal[0] & 0x03) << 8) |

			((gpadc_cal[1] & 0x3F) << 2) |

			((gpadc_cal[2] & 0xC0) >> 6));



		vmain_low = ((gpadc_cal[2] & 0x3E) >> 1);



		gpadc->cal_data[ADC_INPUT_VMAIN].gain = CALIB_SCALE *

			(19500 - 315) /	(vmain_high - vmain_low);



		gpadc->cal_data[ADC_INPUT_VMAIN].offset = CALIB_SCALE * 19500 -

			(CALIB_SCALE * (19500 - 315) /

			 (vmain_high - vmain_low)) * vmain_high;

	} else {

		gpadc->cal_data[ADC_INPUT_VMAIN].gain = 0;

	}



	/* Calculate gain and offset for BTEMP if all reads succeeded */

	if (!(ret[2] < 0 || ret[3] < 0 || ret[4] < 0)) {

		btemp_high = (((gpadc_cal[2] & 0x01) << 9) |

			(gpadc_cal[3] << 1) |

			((gpadc_cal[4] & 0x80) >> 7));



		btemp_low = ((gpadc_cal[4] & 0x7C) >> 2);



		gpadc->cal_data[ADC_INPUT_BTEMP].gain =

			CALIB_SCALE * (1300 - 21) / (btemp_high - btemp_low);



		gpadc->cal_data[ADC_INPUT_BTEMP].offset = CALIB_SCALE * 1300 -

			(CALIB_SCALE * (1300 - 21) /

			(btemp_high - btemp_low)) * btemp_high;

	} else {

		gpadc->cal_data[ADC_INPUT_BTEMP].gain = 0;

	}



	/* Calculate gain and offset for VBAT if all reads succeeded */

	if (!(ret[4] < 0 || ret[5] < 0 || ret[6] < 0)) {

		vbat_high = (((gpadc_cal[4] & 0x03) << 8) | gpadc_cal[5]);

		vbat_low = ((gpadc_cal[6] & 0xFC) >> 2);



		gpadc->cal_data[ADC_INPUT_VBAT].gain = CALIB_SCALE *

			(4700 - 2380) /	(vbat_high - vbat_low);



		gpadc->cal_data[ADC_INPUT_VBAT].offset = CALIB_SCALE * 4700 -

			(CALIB_SCALE * (4700 - 2380) /

			(vbat_high - vbat_low)) * vbat_high;

	} else {

		gpadc->cal_data[ADC_INPUT_VBAT].gain = 0;

	}



	dev_dbg(gpadc->dev, "VMAIN gain %llu offset %llu\n",

		gpadc->cal_data[ADC_INPUT_VMAIN].gain,

		gpadc->cal_data[ADC_INPUT_VMAIN].offset);



	dev_dbg(gpadc->dev, "BTEMP gain %llu offset %llu\n",

		gpadc->cal_data[ADC_INPUT_BTEMP].gain,

		gpadc->cal_data[ADC_INPUT_BTEMP].offset);



	dev_dbg(gpadc->dev, "VBAT gain %llu offset %llu\n",

		gpadc->cal_data[ADC_INPUT_VBAT].gain,

		gpadc->cal_data[ADC_INPUT_VBAT].offset);

}



static int __devinit ab8500_gpadc_probe(struct platform_device *pdev)

{

	int ret = 0;
@@ -269,6 +544,7 @@ static int __devinit ab8500_gpadc_probe(struct platform_device *pdev) 
		dev_err(gpadc->dev, "failed to get vtvout LDO\n");

		goto fail_irq;

	}

	ab8500_gpadc_read_calibration_data(gpadc);

	list_add_tail(&gpadc->node, &ab8500_gpadc_list);

	dev_dbg(gpadc->dev, "probe success\n");

	return 0;
@@ -318,6 +594,6 @@ subsys_initcall_sync(ab8500_gpadc_init); 
module_exit(ab8500_gpadc_exit);



MODULE_LICENSE("GPL v2");

MODULE_AUTHOR("Arun R Murthy, Daniel Willerud");

MODULE_AUTHOR("Arun R Murthy, Daniel Willerud, Johan Palsson");

MODULE_ALIAS("platform:ab8500_gpadc");

MODULE_DESCRIPTION("AB8500 GPADC driver");

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