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Commit c21c2bc6 authored by Oliver Wang's avatar Oliver Wang Committed by Gerrit - the friendly Code Review server
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input: sensors: add LTR553 auto gain switch feature 



LTR553 ambient light data is not sensitive under low light intensity.
Add auto gain switch feature to improve the resolution and
sensitivity.

Change-Id: Ibc456dd7ef4cc1b0a5676142bb0f7495fdd6b7c8
Signed-off-by: default avatarOliver Wang <mengmeng@codeaurora.org>
parent 82dae81f

Documentation/devicetree/bindings/input/misc/ltr553.txt

+4 −0
Original line number Diff line number Diff line
@@ -39,6 +39,9 @@ Required properties: 
	light ratio above 0.99.

 - liteon,wakeup-threshold	: Threshold in centimeter to wake up SoC in

	suspend mode when proximity is enabled.

 - liteon,als-sensitivity	: Ambient light sensitivity in lux. This array

	configures how much light intensity change will trigger a light sensor

	event under different als gain configuration. The array size must be 8.



 Example:
@@ -59,5 +62,6 @@ Required properties: 
		 liteon,ps-pulses = <4>;

		 liteon,wakeup-threshold = <4>;

		 liteon,als-integration-time = <0>;

		 liteon,als-sensitivity = <6000 3200 1600 800 0 0 130 1>;

	 };

 }

drivers/input/misc/ltr553.c

+173 −54
Original line number Diff line number Diff line
@@ -79,6 +79,10 @@ 


#define LTR553_CALIBRATE_SAMPLES	15



#define ALS_GAIN_SWITCH_THRESHOLD	60000



#define LTR553_ALS_INVALID(value)	(value & 0x80)



/* LTR553 ALS data is 16 bit */

#define ALS_DATA_MASK			0xffff

#define ALS_LOW_BYTE(data)		((data) & 0xff)
@@ -150,7 +154,6 @@ struct ltr553_data { 
	int			als_persist;

	int			als_integration_time;

	int			als_measure_rate;

	int			als_sensitivity;

	int			ps_led;

	int			ps_pulses;

	int			ps_measure_rate;
@@ -233,6 +236,8 @@ static int ps_mrr_table[] = { 50, 70, 100, 200, 500, 1000, 2000, 10, 
/* Tuned for devices with rubber */

static int ps_distance_table[] =  { 790, 337, 195, 114, 78, 62, 50 };



static int sensitivity_table[] = {150, 150, 100, 100, 0, 0, 100, 1};



static struct sensors_classdev als_cdev = {

	.name = "ltr553-light",

	.vendor = "Lite-On Technology Corp",
@@ -487,18 +492,16 @@ static int ltr553_parse_dt(struct device *dev, struct ltr553_data *ltr) 
	}

	/* 4 & 5 are reserved */

	if ((value > 0x7) || (value == 0x4) || (value == 0x5)) {

		dev_err(dev, "liteon,als-integration-time out of range\n");

		dev_err(dev, "liteon,als-gain invalid\n");

		return -EINVAL;

	}

	ltr->als_gain = value;



	/* als sensitivity */

	rc = of_property_read_u32(dp, "liteon,als-sensitivity", &value);

	if (rc) {

		dev_err(dev, "read liteon,als-sensitivity failed. Drop to default\n");

		value = LTR553_ALS_SENSITIVITY;

	}

	ltr->als_sensitivity = value;

	rc = of_property_read_u32_array(dp, "liteon,als-sensitivity",

			sensitivity_table, ARRAY_SIZE(sensitivity_table));

	if (rc)

		dev_info(dev, "read liteon,als-sensitivity failed. Drop to default\n");



	/* als equation map */

	rc = of_property_read_u32_array(dp, "liteon,als-equation-0",
@@ -596,6 +599,7 @@ static int ltr553_init_input(struct ltr553_data *ltr) 
static int ltr553_init_device(struct ltr553_data *ltr)

{

	int rc;

	unsigned int tmp;



	/* Enable als/ps interrupt */

	rc = regmap_write(ltr->regmap, LTR553_REG_INTERRUPT,
@@ -655,6 +659,21 @@ static int ltr553_init_device(struct ltr553_data *ltr) 
		return rc;

	}



	/* set up als gain */

	rc = regmap_read(ltr->regmap, LTR553_REG_ALS_CTL, &tmp);

	if (rc) {

		dev_err(&ltr->i2c->dev, "read %d register failed\n",

				LTR553_REG_ALS_CTL);

		return rc;

	}

	rc = regmap_write(ltr->regmap, LTR553_REG_ALS_CTL,

			(tmp & (~0x1c)) | (ltr->als_gain << 2));

	if (rc) {

		dev_err(&ltr->i2c->dev, "write %d register failed\n",

				LTR553_REG_ALS_CTL);

		return rc;

	}



	return 0;

}
@@ -675,9 +694,9 @@ static int ltr553_calc_lux(int ch0data, int ch1data, int gain, 
	ratio = ch1data * 100 / (ch0data + ch1data);

	if (ratio < 45)

		eqtn = &eqtn_map[0];

	else if ((ratio >= 45) && (ratio < 68))

	else if ((ratio >= 45) && (ratio < 74))

		eqtn = &eqtn_map[1];

	else if ((ratio >= 68) && (ratio < 99))

	else if ((ratio >= 74) && (ratio < 99))

		eqtn = &eqtn_map[2];

	else

		eqtn = &eqtn_map[3];
@@ -730,6 +749,123 @@ static int ltr553_calc_adc(int ratio, int lux, int gain, 
	return result <= 0 ? 1 : result;

}



/* update als gain and threshold */

static int ltr553_als_update_setting(struct ltr553_data *ltr,

		unsigned int ch0data, unsigned int ch1data,

		unsigned int als_int_fac)

{

	int gain_index;

	unsigned int config;

	unsigned int ratio;

	unsigned int adc_base;

	int rc;

	int adc;

	int i;

	u8 als_data[4];



	for (i = ARRAY_SIZE(als_gain_table) - 1; i >= 0; i--) {

		if ((i == 4) || (i == 5))

			continue;



		if ((ch0data + ch1data) * als_gain_table[i] /

				als_gain_table[ltr->als_gain] <

				ALS_GAIN_SWITCH_THRESHOLD)

			break;

	}



	gain_index = i < 0 ? 0 : i;



	/*

	 * Disable als and enable it again to avoid incorrect value.

	 * Updating als gain during als measurement cycle will cause

	 * incorrect light sensor adc value. The logic here is to handle

	 * this scenario.

	 */



	if (ltr->als_gain != gain_index) {

		rc = regmap_read(ltr->regmap, LTR553_REG_ALS_CTL, &config);

		if (rc) {

			dev_err(&ltr->i2c->dev, "read %d failed.(%d)\n",

					LTR553_REG_ALS_CTL, rc);

			return rc;

		}



		/* disable als sensor */

		rc = regmap_write(ltr->regmap, LTR553_REG_ALS_CTL,

				config & (~0x1));

		if (rc) {

			dev_err(&ltr->i2c->dev, "write %d failed.(%d)\n",

					LTR553_REG_ALS_CTL, rc);

			return rc;

		}



		/* write new als gain */

		rc = regmap_write(ltr->regmap, LTR553_REG_ALS_CTL,

				(config & (~0x1c)) | (gain_index << 2));

		if (rc) {

			dev_err(&ltr->i2c->dev, "write %d register failed\n",

					LTR553_REG_ALS_CTL);

			return rc;

		}

	}



	if ((ch0data == 0) && (ch1data == 0)) {

		adc = 1;

	} else {

		ratio = ch1data * 100 / (ch0data + ch1data);

		dev_dbg(&ltr->i2c->dev, "ratio:%d\n", ratio);

		adc = ltr553_calc_adc(ratio, sensitivity_table[gain_index],

				als_gain_table[gain_index], als_int_fac);

	}



	dev_dbg(&ltr->i2c->dev, "adc:%d\n", adc);



	/* catch'ya! */

	adc_base = ch0data * als_gain_table[gain_index] /

		als_gain_table[ltr->als_gain];



	/* upper threshold */

	if (adc_base + adc > ALS_DATA_MASK) {

		als_data[0] = 0xff;

		als_data[1] = 0xff;

	} else {

		als_data[0] = ALS_LOW_BYTE(adc_base + adc);

		als_data[1] = ALS_HIGH_BYTE(adc_base + adc);

	}



	/* lower threshold */

	if (adc_base < adc) {

		als_data[2] = 0x0;

		als_data[3] = 0x0;

	} else {

		als_data[2] = ALS_LOW_BYTE(adc_base - adc);

		als_data[3] = ALS_HIGH_BYTE(adc_base - adc);

	}



	rc = regmap_bulk_write(ltr->regmap, LTR553_REG_ALS_THRES_UP_0,

			als_data, 4);

	if (rc) {

		dev_err(&ltr->i2c->dev, "write %d failed.(%d)\n",

				LTR553_REG_ALS_THRES_UP_0, rc);

		return rc;

	}



	if (ltr->als_gain != gain_index) {

		/* enable als_sensor */

		rc = regmap_write(ltr->regmap, LTR553_REG_ALS_CTL,

				(config & (~0x1c)) | (gain_index << 2) | 0x1);

		if (rc) {

			dev_err(&ltr->i2c->dev, "write %d failed.(%d)\n",

					LTR553_REG_ALS_CTL, rc);

			return rc;

		}



		ltr->als_gain = gain_index;

	}



	return 0;

}



static int ltr553_process_data(struct ltr553_data *ltr, int als_ps)

{

	unsigned int als_int_fac;
@@ -741,8 +877,6 @@ static int ltr553_process_data(struct ltr553_data *ltr, int als_ps) 
	int lux;

	unsigned int ch0data;

	unsigned int ch1data;

	int adc;

	int ratio;



	u8 ps_data[4];

	int i;
@@ -778,7 +912,15 @@ static int ltr553_process_data(struct ltr553_data *ltr, int als_ps) 
				lux, als_data[0], als_data[1],

				als_data[2], als_data[3]);



		if (lux != ltr->last_als) {

		rc = regmap_read(ltr->regmap, LTR553_REG_ALS_PS_STATUS, &tmp);

		if (rc) {

			dev_err(&ltr->i2c->dev, "read %d failed.(%d)\n",

					LTR553_REG_ALS_PS_STATUS, rc);

			goto exit;

		}





		if ((lux != ltr->last_als) && (!LTR553_ALS_INVALID(tmp))) {

			input_report_abs(ltr->input_light, ABS_MISC, lux);

			input_event(ltr->input_light, EV_SYN, SYN_TIME_SEC,

					ktime_to_timespec(timestamp).tv_sec);
@@ -790,44 +932,21 @@ static int ltr553_process_data(struct ltr553_data *ltr, int als_ps) 
		}



		ltr->last_als = lux;

		/* Set up threshold */

		tmp = als_data[2] | (als_data[3] << 8);

		if ((ch0data == 0) && (ch1data == 0)) {

			adc = 1;

		} else {

			ratio = ch1data * 100 / (ch0data + ch1data);

			dev_dbg(&ltr->i2c->dev, "ratio:%d\n", ratio);

			adc = ltr553_calc_adc(ratio, ltr->als_sensitivity,

				als_gain_table[ltr->als_gain], als_int_fac);

		}



		dev_dbg(&ltr->i2c->dev, "adc:%d\n", adc);

		dev_dbg(&ltr->i2c->dev, "previous als_gain:%d\n",

				ltr->als_gain);



		/* upper threshold */

		if (tmp + adc > ALS_DATA_MASK) {

			als_data[0] = 0xff;

			als_data[1] = 0xff;

		} else {

			als_data[0] = ALS_LOW_BYTE(tmp + adc);

			als_data[1] = ALS_HIGH_BYTE(tmp + adc);

		}



		/* lower threshold */

		if (tmp < adc) {

			als_data[2] = 0x0;

			als_data[3] = 0x0;

		} else {

			als_data[2] = ALS_LOW_BYTE(tmp - adc);

			als_data[3] = ALS_HIGH_BYTE(tmp - adc);

		}



		rc = regmap_bulk_write(ltr->regmap, LTR553_REG_ALS_THRES_UP_0,

				als_data, 4);

		rc = ltr553_als_update_setting(ltr, ch0data, ch1data,

				als_int_fac);

		if (rc) {

			dev_err(&ltr->i2c->dev, "write %d failed.(%d)\n",

					LTR553_REG_ALS_THRES_UP_0, rc);

			dev_err(&ltr->i2c->dev, "update setting failed\n");

			goto exit;

		}



		dev_dbg(&ltr->i2c->dev, "new als_gain:%d\n",

				ltr->als_gain);





	} else { /* process ps value */

		rc = regmap_bulk_read(ltr->regmap, LTR553_REG_PS_DATA_0,

				ps_data, 2);
@@ -1035,7 +1154,7 @@ static int ltr553_enable_ps(struct ltr553_data *ltr, int enable) 
		if (rc) {

			dev_err(&ltr->i2c->dev, "write %d failed.(%d)\n",

					LTR553_REG_PS_CTL, rc);

			return rc;

			goto exit;

		}



		ltr->ps_enabled = false;
@@ -1103,14 +1222,14 @@ static int ltr553_enable_als(struct ltr553_data *ltr, int enable) 
		if (rc) {

			dev_err(&ltr->i2c->dev, "write %d failed.(%d)\n",

					LTR553_REG_ALS_CTL, rc);

			return rc;

			goto exit;

		}



		ltr->als_enabled = false;

	}



exit:

	return 0;

	return rc;

}



static void ltr553_als_enable_work(struct work_struct *work)