On Thu, 2 May 2019 11:14:27 -0500
Adam Michaelis <adam.michaelis@xxxxxxxxxxxxxxxxxxx> wrote:
> Adding configurable (via device tree) options to select either an external
> reference voltage (default, original implementation) or one of the two
> internal reference voltages provided by the AD7949 part family.
>
> Signed-off-by: Adam Michaelis <adam.michaelis@xxxxxxxxxxxxxxxxxxx>
Hi Adam,
Clearly the comments I made on the DT patch will follow through to changes
in here.
A few minor comments below.
Jonathan
> ---
> V2: Add some defines to reduce use of magic numbers.
> ---
> drivers/iio/adc/ad7949.c | 135 +++++++++++++++++++++++++++++++++++++----------
> 1 file changed, 108 insertions(+), 27 deletions(-)
>
> diff --git a/drivers/iio/adc/ad7949.c b/drivers/iio/adc/ad7949.c
> index ac0ffff6c5ae..afc1361af5fb 100644
> --- a/drivers/iio/adc/ad7949.c
> +++ b/drivers/iio/adc/ad7949.c
> @@ -11,12 +11,27 @@
> #include <linux/module.h>
> #include <linux/regulator/consumer.h>
> #include <linux/spi/spi.h>
> -
> -#define AD7949_MASK_CHANNEL_SEL GENMASK(9, 7)
> -#define AD7949_MASK_TOTAL GENMASK(13, 0)
> -#define AD7949_OFFSET_CHANNEL_SEL 7
> -#define AD7949_CFG_READ_BACK 0x1
> -#define AD7949_CFG_REG_SIZE_BITS 14
> +#include <linux/of.h>
> +
> +#define AD7949_CFG_REG_SIZE_BITS 14
> +#define AD7949_CFG_MASK_TOTAL GENMASK(13, 0)
> +#define AD7949_CFG_OVERWRITE_SHIFT 13
> +#define AD7949_CFG_CHAN_CFG_UNIPOLAR_GND 0x7
> +#define AD7949_CFG_CHAN_CFG_MASK GENMASK(12, 10)
> +#define AD7949_CFG_CHAN_CFG_SHIFT 10
> +#define AD7949_CFG_CHAN_SEL_MASK GENMASK(9, 7)
> +#define AD7949_CFG_CHAN_SEL_SHIFT 7
> +#define AD7949_CFG_BW_FULL 1
> +#define AD7949_CFG_BW_SHIFT 6
> +#define AD7949_CFG_BW_MASK GENMASK(6, 6)
> +#define AD7949_CFG_REF_SEL_MASK GENMASK(5, 3)
> +#define AD7949_CFG_REF_SEL_SHIFT 3
> +#define AD7949_CFG_SEQ_DISABLED 0x0
> +#define AD7949_CFG_SEQ_SHIFT 1
> +#define AD7949_CFG_SEQ_MASK GENMASK(2, 1)
Where possible use the FIELD_PREP and FIELD_GET macros
to avoid needing to define both a _SHIFT and a _MASK.
IIRC the mask needs to be a compile time constant, but I think that
is always true with these.
> +#define AD7949_CFG_READBACK_EN 0
> +#define AD7949_CFG_READBACK_DIS 1
> +#define AD7949_CFG_READBACK_MASK GENMASK(0, 0)
>
> enum {
> ID_AD7949 = 0,
> @@ -24,6 +39,18 @@ enum {
> ID_AD7689,
> };
>
> +enum ad7949_ref_sel {
> + AD7949_REF_2V5 = 0, /* 2.5V internal ref + temp sensor */
> + AD7949_REF_4V0, /* 4.096V internal ref + temp sensor */
> + AD7949_REF_EXT_TEMP, /* External ref + temp sensor, no buffer */
> + AD7949_REF_EXT_TEMP_BUF, /* External ref + temp sensor + buffer */
> + AD7949_REF_RSRV_4,
> + AD7949_REF_RSRV_5,
> + AD7949_REF_EXT, /* External ref, no temp, no buffer */
> + AD7949_REF_EXT_BUF, /* External ref + buffer, no temp */
> + AD7949_REF_MAX,
> +};
> +
> struct ad7949_adc_spec {
> u8 num_channels;
> u8 resolution;
> @@ -41,6 +68,7 @@ struct ad7949_adc_spec {
> * @vref: regulator generating Vref
> * @iio_dev: reference to iio structure
> * @spi: reference to spi structure
> + * @ref_sel: selected reference voltage source
> * @resolution: resolution of the chip
> * @cfg: copy of the configuration register
> * @current_channel: current channel in use
> @@ -51,6 +79,7 @@ struct ad7949_adc_chip {
> struct regulator *vref;
> struct iio_dev *indio_dev;
> struct spi_device *spi;
> + enum ad7949_ref_sel ref_sel;
> u8 resolution;
> u16 cfg;
> unsigned int current_channel;
> @@ -59,7 +88,7 @@ struct ad7949_adc_chip {
>
> static bool ad7949_spi_cfg_is_read_back(struct ad7949_adc_chip *ad7949_adc)
> {
> - if (!(ad7949_adc->cfg & AD7949_CFG_READ_BACK))
> + if (!(ad7949_adc->cfg & AD7949_CFG_READBACK_MASK))
> return true;
>
> return false;
> @@ -91,7 +120,7 @@ static int ad7949_spi_write_cfg(struct ad7949_adc_chip *ad7949_adc, u16 val,
> };
>
> ad7949_adc->cfg = (val & mask) | (ad7949_adc->cfg & ~mask);
> - ad7949_adc->buffer = ad7949_adc->cfg << shift;
> + ad7949_adc->buffer = (ad7949_adc->cfg & AD7949_CFG_MASK_TOTAL) << shift;
> spi_message_init_with_transfers(&msg, tx, 1);
> ret = spi_sync(ad7949_adc->spi, &msg);
>
> @@ -119,8 +148,8 @@ static int ad7949_spi_read_channel(struct ad7949_adc_chip *ad7949_adc, int *val,
> };
>
> ret = ad7949_spi_write_cfg(ad7949_adc,
> - channel << AD7949_OFFSET_CHANNEL_SEL,
> - AD7949_MASK_CHANNEL_SEL);
> + channel << AD7949_CFG_CHAN_SEL_SHIFT,
> + AD7949_CFG_CHAN_SEL_MASK);
> if (ret)
> return ret;
>
> @@ -187,11 +216,20 @@ 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;
> + if (ad7949_adc->vref) {
> + ret = regulator_get_voltage(ad7949_adc->vref);
> + if (ret < 0)
> + return ret;
> +
> + *val = ret / 5000;
> + } else if (ad7949_adc->ref_sel == AD7949_REF_2V5) {
> + *val = 2500;
> + } else if (ad7949_adc->ref_sel == AD7949_REF_4V0) {
> + *val = 4096;
> + } else {
> + return -EINVAL;
> + }
>
> - *val = ret / 5000;
> return IIO_VAL_INT;
> }
>
> @@ -209,7 +247,7 @@ static int ad7949_spi_reg_access(struct iio_dev *indio_dev,
> *readval = ad7949_adc->cfg;
> else
> ret = ad7949_spi_write_cfg(ad7949_adc,
> - writeval & AD7949_MASK_TOTAL, AD7949_MASK_TOTAL);
> + writeval & AD7949_CFG_MASK_TOTAL, AD7949_CFG_MASK_TOTAL);
>
> return ret;
> }
> @@ -223,10 +261,33 @@ static int ad7949_spi_init(struct ad7949_adc_chip *ad7949_adc)
> {
> int ret;
> int val;
> + u16 adc_config = 0;
>
> - /* Sequencer disabled, CFG readback disabled, IN0 as default channel */
> ad7949_adc->current_channel = 0;
> - ret = ad7949_spi_write_cfg(ad7949_adc, 0x3C79, AD7949_MASK_TOTAL);
> + ad7949_adc->cfg = 0;
> +
> + /*
> + * 14-bit configuration register (pg 12 of AD7949 Datasheet):
> + * | 13 | 12 - 10 | 9 - 7 | 6 | 5 -3 | 2 - 1 | 0 |
> + * | CFG | INCC | INx | BW | REF | SEQ | RB |
> + */
Given this is now all opaque (as it should be) the comment isn't really
very useful any more so I'd drop it.
> + adc_config = 1 << AD7949_CFG_OVERWRITE_SHIFT;
> + adc_config |=
> + (AD7949_CFG_CHAN_CFG_UNIPOLAR_GND << AD7949_CFG_CHAN_CFG_SHIFT)
> + & AD7949_CFG_CHAN_CFG_MASK;
> + adc_config |= (ad7949_adc->current_channel << AD7949_CFG_CHAN_SEL_SHIFT)
> + & AD7949_CFG_CHAN_SEL_MASK;
> + adc_config |= (AD7949_CFG_BW_FULL << AD7949_CFG_BW_SHIFT) &
> + AD7949_CFG_BW_MASK;
> + adc_config |= (ad7949_adc->ref_sel << AD7949_CFG_REF_SEL_SHIFT) &
> + AD7949_CFG_REF_SEL_MASK;
> + adc_config |= (AD7949_CFG_SEQ_DISABLED << AD7949_CFG_SEQ_SHIFT) &
> + AD7949_CFG_SEQ_MASK;
Perhaps could used FIELD_PREP to do this in a cleaner fashion.
> + adc_config |= AD7949_CFG_READBACK_DIS;
> +
> + ret = ad7949_spi_write_cfg(ad7949_adc,
> + adc_config,
> + AD7949_CFG_MASK_TOTAL);
>
> /*
> * Do two dummy conversions to apply the first configuration setting.
> @@ -245,6 +306,7 @@ static int ad7949_spi_probe(struct spi_device *spi)
> struct ad7949_adc_chip *ad7949_adc;
> struct iio_dev *indio_dev;
> int ret;
> + u32 temp;
>
> indio_dev = devm_iio_device_alloc(dev, sizeof(*ad7949_adc));
> if (!indio_dev) {
> @@ -263,21 +325,38 @@ static int ad7949_spi_probe(struct spi_device *spi)
> ad7949_adc = iio_priv(indio_dev);
> ad7949_adc->indio_dev = indio_dev;
> ad7949_adc->spi = spi;
> + ad7949_adc->vref = NULL;
>
> spec = &ad7949_adc_spec[spi_get_device_id(spi)->driver_data];
> indio_dev->num_channels = spec->num_channels;
> ad7949_adc->resolution = spec->resolution;
>
> - 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 = of_property_read_u32(ad7949_adc->indio_dev->dev.of_node,
> + "adi,reference-select",
> + &temp);
> + if ((ret == 0) && (temp < AD7949_REF_MAX) &&
> + (temp != AD7949_REF_RSRV_4) &&
> + (temp != AD7949_REF_RSRV_5)) {
> + ad7949_adc->ref_sel = (enum ad7949_ref_sel)temp;
> + } else {
> + ad7949_adc->ref_sel = AD7949_REF_EXT_BUF;
> + dev_warn(dev, "using external Vref by default\n");
> }
>
> - ret = regulator_enable(ad7949_adc->vref);
> - if (ret < 0) {
> - dev_err(dev, "fail to enable regulator\n");
> - return ret;
> + /* Check whether using external Vref */
> + if ((ad7949_adc->ref_sel != AD7949_REF_2V5) &&
> + (ad7949_adc->ref_sel != AD7949_REF_4V0)) {
> + 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);
> @@ -298,7 +377,8 @@ static int ad7949_spi_probe(struct spi_device *spi)
>
> err:
> mutex_destroy(&ad7949_adc->lock);
> - regulator_disable(ad7949_adc->vref);
> + if (ad7949_adc->vref)
> + regulator_disable(ad7949_adc->vref);
>
> return ret;
> }
> @@ -310,7 +390,8 @@ static int ad7949_spi_remove(struct spi_device *spi)
>
> iio_device_unregister(indio_dev);
> mutex_destroy(&ad7949_adc->lock);
> - regulator_disable(ad7949_adc->vref);
> + if (ad7949_adc->vref)
> + regulator_disable(ad7949_adc->vref);
>
> return 0;
> }
