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[198.48.202.89]) by smtp.gmail.com with ESMTPSA id p188sm2380514qka.114.2021.07.27.16.29.23 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 27 Jul 2021 16:29:23 -0700 (PDT) From: Liam Beguin To: liambeguin@gmail.com, lars@metafoo.de, Michael.Hennerich@analog.com, jic23@kernel.org, charles-antoine.couret@essensium.com, Nuno.Sa@analog.com Cc: linux-kernel@vger.kernel.org, linux-iio@vger.kernel.org, devicetree@vger.kernel.org, robh+dt@kernel.org Subject: [PATCH v4 3/5] iio: adc: ad7949: add support for internal vref Date: Tue, 27 Jul 2021 19:29:04 -0400 Message-Id: <20210727232906.980769-4-liambeguin@gmail.com> X-Mailer: git-send-email 2.30.1.489.g328c10930387 In-Reply-To: <20210727232906.980769-1-liambeguin@gmail.com> References: <20210727232906.980769-1-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 | 132 +++++++++++++++++++++++++++++++++------ 1 file changed, 114 insertions(+), 18 deletions(-) diff --git a/drivers/iio/adc/ad7949.c b/drivers/iio/adc/ad7949.c index f1702c54c8be..eaea8f5e87d8 100644 --- a/drivers/iio/adc/ad7949.c +++ b/drivers/iio/adc/ad7949.c @@ -35,7 +35,11 @@ /* REF: reference/buffer selection */ #define AD7949_CFG_BIT_REF GENMASK(5, 3) -#define AD7949_CFG_VAL_REF_EXT_BUF 7 +#define AD7949_CFG_VAL_REF_EXT_TEMP_BUF 3 +#define AD7949_CFG_VAL_REF_EXT_TEMP 2 +#define AD7949_CFG_VAL_REF_INT_4096 1 +#define AD7949_CFG_VAL_REF_INT_2500 0 +#define AD7949_CFG_VAL_REF_EXTERNAL BIT(1) /* SEQ: channel sequencer. Allows for scanning channels */ #define AD7949_CFG_BIT_SEQ GENMASK(2, 1) @@ -60,6 +64,14 @@ static const struct ad7949_adc_spec ad7949_adc_spec[] = { [ID_AD7689] = { .num_channels = 8, .resolution = 16 }, }; +/** + * struct ad7949_channel - ADC Channel parameters + * @refsel: reference selection + */ +struct ad7949_channel { + u32 refsel; +}; + /** * struct ad7949_adc_chip - AD ADC chip * @lock: protects write sequences @@ -77,6 +89,7 @@ struct ad7949_adc_chip { struct regulator *vref; struct iio_dev *indio_dev; struct spi_device *spi; + struct ad7949_channel *channels; u8 resolution; u8 bits_per_word; u16 cfg; @@ -133,6 +146,7 @@ static int ad7949_spi_read_channel(struct ad7949_adc_chip *ad7949_adc, int *val, int ret; int i; struct spi_message msg; + struct ad7949_channel *ad7949_chan = &ad7949_adc->channels[channel]; struct spi_transfer tx[] = { { .rx_buf = &ad7949_adc->buffer, @@ -149,8 +163,9 @@ static int ad7949_spi_read_channel(struct ad7949_adc_chip *ad7949_adc, int *val, */ for (i = 0; i < 2; i++) { ret = ad7949_spi_write_cfg(ad7949_adc, - FIELD_PREP(AD7949_CFG_BIT_INX, channel), - AD7949_CFG_BIT_INX); + FIELD_PREP(AD7949_CFG_BIT_INX, channel) | + FIELD_PREP(AD7949_CFG_BIT_REF, ad7949_chan->refsel), + AD7949_CFG_BIT_INX | AD7949_CFG_BIT_REF); if (ret) return ret; if (channel == ad7949_adc->current_channel) @@ -219,6 +234,7 @@ static int ad7949_spi_read_raw(struct iio_dev *indio_dev, int *val, int *val2, long mask) { struct ad7949_adc_chip *ad7949_adc = iio_priv(indio_dev); + struct ad7949_channel *ad7949_chan = &ad7949_adc->channels[chan->channel]; int ret; if (!val) @@ -236,12 +252,26 @@ 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_chan->refsel) { + case AD7949_CFG_VAL_REF_INT_2500: + *val = 2500; + break; + case AD7949_CFG_VAL_REF_INT_4096: + *val = 4096; + break; + case AD7949_CFG_VAL_REF_EXT_TEMP: + case AD7949_CFG_VAL_REF_EXT_TEMP_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; @@ -280,7 +310,7 @@ 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_FULL, 1) | - FIELD_PREP(AD7949_CFG_BIT_REF, AD7949_CFG_VAL_REF_EXT_BUF) | + FIELD_PREP(AD7949_CFG_BIT_REF, ad7949_adc->channels[0].refsel) | FIELD_PREP(AD7949_CFG_BIT_SEQ, 0x0) | FIELD_PREP(AD7949_CFG_BIT_RBN, 1); @@ -296,14 +326,24 @@ static int ad7949_spi_init(struct ad7949_adc_chip *ad7949_adc) return ret; } +static void ad7949_disable_reg(void *reg) +{ + regulator_disable(reg); +} + static int ad7949_spi_probe(struct spi_device *spi) { u32 spi_ctrl_mask = spi->controller->bits_per_word_mask; struct device *dev = &spi->dev; const struct ad7949_adc_spec *spec; struct ad7949_adc_chip *ad7949_adc; + struct ad7949_channel *ad7949_chan; + struct fwnode_handle *child; struct iio_dev *indio_dev; + int mode; + u32 tmp; int ret; + int i; indio_dev = devm_iio_device_alloc(dev, sizeof(*ad7949_adc)); if (!indio_dev) { @@ -337,16 +377,74 @@ static int ad7949_spi_probe(struct spi_device *spi) return -EINVAL; } - ad7949_adc->vref = devm_regulator_get(dev, "vref"); + /* Setup external voltage ref, buffered? */ + ad7949_adc->vref = devm_regulator_get(dev, "vrefin"); if (IS_ERR(ad7949_adc->vref)) { - dev_err(dev, "fail to request regulator\n"); - return PTR_ERR(ad7949_adc->vref); + /* unbuffered? */ + ad7949_adc->vref = devm_regulator_get(dev, "vref"); + if (IS_ERR(ad7949_adc->vref)) { + /* Internal then */ + mode = AD7949_CFG_VAL_REF_INT_4096; + } + mode = AD7949_CFG_VAL_REF_EXT_TEMP; } + mode = AD7949_CFG_VAL_REF_EXT_TEMP_BUF; - ret = regulator_enable(ad7949_adc->vref); - if (ret < 0) { - dev_err(dev, "fail to enable regulator\n"); - return ret; + if (mode & AD7949_CFG_VAL_REF_EXTERNAL) { + ret = regulator_enable(ad7949_adc->vref); + if (ret < 0) { + dev_err(dev, "fail to enable regulator\n"); + return ret; + } + + ret = devm_add_action_or_reset(dev, ad7949_disable_reg, + ad7949_adc->vref); + if (ret) + return ret; + } + + ad7949_adc->channels = devm_kcalloc(dev, spec->num_channels, + sizeof(*ad7949_adc->channels), + GFP_KERNEL); + if (!ad7949_adc->channels) { + dev_err(dev, "unable to allocate ADC channels\n"); + return -ENOMEM; + } + + /* Initialize all channel structures */ + for (i = 0; i < spec->num_channels; i++) + ad7949_adc->channels[i].refsel = mode; + + /* Read channel specific information form the devicetree */ + device_for_each_child_node(dev, child) { + ret = fwnode_property_read_u32(child, "reg", &i); + if (ret) { + dev_err(dev, "missing reg property in %pfw\n", child); + fwnode_handle_put(child); + return ret; + } + + ad7949_chan = &ad7949_adc->channels[i]; + + ret = fwnode_property_read_u32(child, "adi,internal-ref-microvolt", &tmp); + if (ret < 0 && ret != -EINVAL) { + dev_err(dev, "invalid internal reference in %pfw\n", child); + fwnode_handle_put(child); + return ret; + } + + switch (tmp) { + case 2500000: + ad7949_chan->refsel = AD7949_CFG_VAL_REF_INT_2500; + break; + case 4096000: + ad7949_chan->refsel = AD7949_CFG_VAL_REF_INT_4096; + break; + default: + dev_err(dev, "unsupported internal voltage reference\n"); + fwnode_handle_put(child); + return -EINVAL; + } } mutex_init(&ad7949_adc->lock); @@ -367,7 +465,6 @@ static int ad7949_spi_probe(struct spi_device *spi) err: mutex_destroy(&ad7949_adc->lock); - regulator_disable(ad7949_adc->vref); return ret; } @@ -379,7 +476,6 @@ static int ad7949_spi_remove(struct spi_device *spi) iio_device_unregister(indio_dev); mutex_destroy(&ad7949_adc->lock); - regulator_disable(ad7949_adc->vref); return 0; }