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Subject[PATCH v1 2/3] iio: adc: tsc2046: add vref support
Date
If VREF pin is attached, we should use external VREF source instead of
the internal. Otherwise we will get wrong measurements on some of channel
types.

Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de>
---
drivers/iio/adc/ti-tsc2046.c | 64 +++++++++++++++++++++++++++++++-----
1 file changed, 55 insertions(+), 9 deletions(-)

diff --git a/drivers/iio/adc/ti-tsc2046.c b/drivers/iio/adc/ti-tsc2046.c
index 0d9436a69cbfb..bbc8b4137b0b1 100644
--- a/drivers/iio/adc/ti-tsc2046.c
+++ b/drivers/iio/adc/ti-tsc2046.c
@@ -8,6 +8,7 @@
#include <linux/bitfield.h>
#include <linux/delay.h>
#include <linux/module.h>
+#include <linux/regulator/consumer.h>
#include <linux/spi/spi.h>

#include <asm/unaligned.h>
@@ -175,6 +176,9 @@ struct tsc2046_adc_priv {
u32 time_per_bit_ns;

struct tsc2046_adc_ch_cfg ch_cfg[TI_TSC2046_MAX_CHAN];
+ bool use_internal_vref;
+ unsigned int vref_mv;
+ struct regulator *vref_reg;
};

#define TI_TSC2046_V_CHAN(index, bits, name) \
@@ -252,7 +256,9 @@ static u8 tsc2046_adc_get_cmd(struct tsc2046_adc_priv *priv, int ch_idx,
case TI_TSC2046_ADDR_AUX:
case TI_TSC2046_ADDR_VBAT:
case TI_TSC2046_ADDR_TEMP0:
- pd |= TI_TSC2046_SER | TI_TSC2046_PD1_VREF_ON;
+ pd |= TI_TSC2046_SER;
+ if (priv->use_internal_vref)
+ pd |= TI_TSC2046_PD1_VREF_ON;
}

return TI_TSC2046_START | FIELD_PREP(TI_TSC2046_ADDR, ch_idx) | pd;
@@ -468,7 +474,7 @@ static int tsc2046_adc_read_raw(struct iio_dev *indio_dev,
* So, it is better to use external voltage-divider driver
* instead, which is calculating complete chain.
*/
- *val = TI_TSC2046_INT_VREF;
+ *val = priv->vref_mv;
*val2 = chan->scan_type.realbits;
return IIO_VAL_FRACTIONAL_LOG2;
}
@@ -781,22 +787,42 @@ static int tsc2046_adc_probe(struct spi_device *spi)
indio_dev->num_channels = dcfg->num_channels;
indio_dev->info = &tsc2046_adc_info;

+ priv->vref_reg = devm_regulator_get_optional(&spi->dev, "vref");
+ if (!IS_ERR(priv->vref_reg)) {
+ ret = regulator_enable(priv->vref_reg);
+ if (ret)
+ return ret;
+
+ ret = regulator_get_voltage(priv->vref_reg);
+ if (ret < 0)
+ goto err_regulator_disable;
+
+ priv->vref_mv = ret / 1000;
+ priv->use_internal_vref = false;
+ } else {
+ /* Use internal reference */
+ priv->vref_mv = TI_TSC2046_INT_VREF;
+ priv->use_internal_vref = true;
+ }
+
tsc2046_adc_parse_fwnode(priv);

ret = tsc2046_adc_setup_spi_msg(priv);
if (ret)
- return ret;
+ goto err_regulator_disable;

mutex_init(&priv->slock);

ret = devm_request_irq(dev, spi->irq, &tsc2046_adc_irq,
IRQF_NO_AUTOEN, indio_dev->name, indio_dev);
if (ret)
- return ret;
+ goto err_regulator_disable;

trig = devm_iio_trigger_alloc(dev, "touchscreen-%s", indio_dev->name);
- if (!trig)
- return -ENOMEM;
+ if (!trig) {
+ ret = -ENOMEM;
+ goto err_regulator_disable;
+ }

priv->trig = trig;
iio_trigger_set_drvdata(trig, indio_dev);
@@ -811,20 +837,39 @@ static int tsc2046_adc_probe(struct spi_device *spi)
ret = devm_iio_trigger_register(dev, trig);
if (ret) {
dev_err(dev, "failed to register trigger\n");
- return ret;
+ goto err_regulator_disable;
}

ret = devm_iio_triggered_buffer_setup(dev, indio_dev, NULL,
&tsc2046_adc_trigger_handler, NULL);
if (ret) {
dev_err(dev, "Failed to setup triggered buffer\n");
- return ret;
+ goto err_regulator_disable;
}

/* set default trigger */
indio_dev->trig = iio_trigger_get(priv->trig);

- return devm_iio_device_register(dev, indio_dev);
+ ret = devm_iio_device_register(dev, indio_dev);
+ if (ret)
+ goto err_regulator_disable;
+
+ return 0;
+
+err_regulator_disable:
+ if (!IS_ERR(priv->vref_reg))
+ regulator_disable(priv->vref_reg);
+
+ return ret;
+}
+
+static void tsc2046_adc_remove(struct spi_device *spi)
+{
+ struct iio_dev *indio_dev = spi_get_drvdata(spi);
+ struct tsc2046_adc_priv *priv = iio_priv(indio_dev);
+
+ if (!IS_ERR(priv->vref_reg))
+ regulator_disable(priv->vref_reg);
}

static const struct of_device_id ads7950_of_table[] = {
@@ -839,6 +884,7 @@ static struct spi_driver tsc2046_adc_driver = {
.of_match_table = ads7950_of_table,
},
.probe = tsc2046_adc_probe,
+ .remove = tsc2046_adc_remove,
};
module_spi_driver(tsc2046_adc_driver);

--
2.30.2
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