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[198.48.202.89]) by smtp.gmail.com with ESMTPSA id m68sm1733234qkc.109.2021.07.08.16.56.35 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 08 Jul 2021 16:56:35 -0700 (PDT) From: Liam Beguin To: liambeguin@gmail.com, lars@metafoo.de, Michael.Hennerich@analog.com, jic23@kernel.org, charles-antoine.couret@essensium.com Cc: linux-kernel@vger.kernel.org, linux-iio@vger.kernel.org, devicetree@vger.kernel.org, robh+dt@kernel.org Subject: [PATCH v1 3/4] iio: adc: ad7949: add support for internal vref Date: Thu, 8 Jul 2021 19:56:17 -0400 Message-Id: <20210708235618.1541335-4-liambeguin@gmail.com> X-Mailer: git-send-email 2.30.1.489.g328c10930387 In-Reply-To: <20210708235618.1541335-1-liambeguin@gmail.com> References: <20210708235618.1541335-1-liambeguin@gmail.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-iio@vger.kernel.org From: Liam Beguin Add support for selecting a custom reference voltage from the devicetree. If an external source is used, a vref regulator should be defined in the devicetree. Signed-off-by: Liam Beguin --- drivers/iio/adc/ad7949.c | 84 +++++++++++++++++++++++++++++++++------- 1 file changed, 69 insertions(+), 15 deletions(-) diff --git a/drivers/iio/adc/ad7949.c b/drivers/iio/adc/ad7949.c index bbc6b56330a3..3c1293922d2e 100644 --- a/drivers/iio/adc/ad7949.c +++ b/drivers/iio/adc/ad7949.c @@ -31,6 +31,7 @@ #define AD7949_CFG_VAL_BW_FULL 1 #define AD7949_CFG_VAL_BW_QUARTER 0 #define AD7949_CFG_BIT_REF GENMASK(5, 3) +#define AD7949_CFG_VAL_REF_EXTERNAL BIT(1) #define AD7949_CFG_BIT_SEQ GENMASK(2, 1) #define AD7949_CFG_BIT_RBN BIT(0) @@ -40,6 +41,33 @@ enum { ID_AD7689, }; +/** + * enum ad7949_ref - Reference selection + * + * AD7949_REF_INT_2500: Internal reference and temperature sensor enabled. + * Vref=2.5V, buffered output + * AD7949_REF_INT_4096: Internal reference and temperature sensor enabled. + * Vref=4.096V, buffered output + * AD7949_REF_EXT_TEMP: Use external reference, temperature sensor enabled. + * Internal buffer disabled + * AD7949_REF_EXT_TEMP_BUF: Use external reference, internal buffer and + * temperature sensor enabled. + * AD7949_REF_RSRV_4: Do not use + * AD7949_REF_RSRV_5: Do not use + * AD7949_REF_EXT: Use external reference, internal buffer and + * temperature sensor disabled. + * AD7949_REF_EXT_BUF: Use external reference, internal buffer enabled. + * Internal reference and temperature sensor disabled. + */ +enum ad7949_ref { + AD7949_REF_INT_2500 = 0, + AD7949_REF_INT_4096, + AD7949_REF_EXT_TEMP, + AD7949_REF_EXT_TEMP_BUF, + AD7949_REF_EXT = 6, + AD7949_REF_EXT_BUF, +}; + struct ad7949_adc_spec { u8 num_channels; u8 resolution; @@ -55,6 +83,7 @@ static const struct ad7949_adc_spec ad7949_adc_spec[] = { * struct ad7949_adc_chip - AD ADC chip * @lock: protects write sequences * @vref: regulator generating Vref + * @refsel: reference selection * @indio_dev: reference to iio structure * @spi: reference to spi structure * @resolution: resolution of the chip @@ -66,6 +95,7 @@ static const struct ad7949_adc_spec ad7949_adc_spec[] = { struct ad7949_adc_chip { struct mutex lock; struct regulator *vref; + enum ad7949_ref refsel; struct iio_dev *indio_dev; struct spi_device *spi; u8 resolution; @@ -241,12 +271,28 @@ static int ad7949_spi_read_raw(struct iio_dev *indio_dev, return IIO_VAL_INT; case IIO_CHAN_INFO_SCALE: - ret = regulator_get_voltage(ad7949_adc->vref); - if (ret < 0) - return ret; + switch (ad7949_adc->refsel) { + case AD7949_REF_INT_2500: + *val = 2500; + break; + case AD7949_REF_INT_4096: + *val = 4096; + break; + case AD7949_REF_EXT_TEMP: + case AD7949_REF_EXT_TEMP_BUF: + case AD7949_REF_EXT: + case AD7949_REF_EXT_BUF: + ret = regulator_get_voltage(ad7949_adc->vref); + if (ret < 0) + return ret; + + /* convert value back to mV */ + *val = ret / 1000; + break; + } - *val = ret / 5000; - return IIO_VAL_INT; + *val2 = (1 << ad7949_adc->resolution) - 1; + return IIO_VAL_FRACTIONAL; } return -EINVAL; @@ -285,7 +331,7 @@ static int ad7949_spi_init(struct ad7949_adc_chip *ad7949_adc) FIELD_PREP(AD7949_CFG_BIT_INCC, AD7949_CFG_VAL_INCC_UNIPOLAR_GND) | FIELD_PREP(AD7949_CFG_BIT_INX, ad7949_adc->current_channel) | FIELD_PREP(AD7949_CFG_BIT_BW, AD7949_CFG_VAL_BW_FULL) | - FIELD_PREP(AD7949_CFG_BIT_REF, AD7949_REF_EXT_BUF) | + FIELD_PREP(AD7949_CFG_BIT_REF, ad7949_adc->refsel) | FIELD_PREP(AD7949_CFG_BIT_SEQ, 0x0) | FIELD_PREP(AD7949_CFG_BIT_RBN, 1); @@ -304,6 +350,7 @@ static int ad7949_spi_init(struct ad7949_adc_chip *ad7949_adc) static int ad7949_spi_probe(struct spi_device *spi) { struct device *dev = &spi->dev; + struct device_node *np = dev->of_node; const struct ad7949_adc_spec *spec; struct ad7949_adc_chip *ad7949_adc; struct iio_dev *indio_dev; @@ -315,6 +362,7 @@ static int ad7949_spi_probe(struct spi_device *spi) return -ENOMEM; } + indio_dev->dev.of_node = np; indio_dev->info = &ad7949_spi_info; indio_dev->name = spi_get_device_id(spi)->name; indio_dev->modes = INDIO_DIRECT_MODE; @@ -330,16 +378,22 @@ static int ad7949_spi_probe(struct spi_device *spi) ad7949_adc->resolution = spec->resolution; ad7949_set_bits_per_word(ad7949_adc); - ad7949_adc->vref = devm_regulator_get(dev, "vref"); - if (IS_ERR(ad7949_adc->vref)) { - dev_err(dev, "fail to request regulator\n"); - return PTR_ERR(ad7949_adc->vref); - } + /* Set default devicetree parameters */ + ad7949_adc->refsel = AD7949_REF_EXT_BUF; + of_property_read_u32(np, "adi,reference-select", &ad7949_adc->refsel); - ret = regulator_enable(ad7949_adc->vref); - if (ret < 0) { - dev_err(dev, "fail to enable regulator\n"); - return ret; + if (ad7949_adc->refsel & AD7949_CFG_VAL_REF_EXTERNAL) { + ad7949_adc->vref = devm_regulator_get(dev, "vref"); + if (IS_ERR(ad7949_adc->vref)) { + dev_err(dev, "fail to request regulator\n"); + return PTR_ERR(ad7949_adc->vref); + } + + ret = regulator_enable(ad7949_adc->vref); + if (ret < 0) { + dev_err(dev, "fail to enable regulator\n"); + return ret; + } } mutex_init(&ad7949_adc->lock);