staging:iio:ad7793: Rework platform data

Currently the platform data for the ad7793 consist just out of the raw default
register settings. This has some downsides, for one we actually don't want to
make all bits configurable and secondly not all register settings are actually
valid. This patch exposes all the options which should be configurable via
platform data as induvidual platform data struct fields. This also allows us to
document the different settings via proper kernel doc.

Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

2 files changed, 123 insertions, 9 deletions

diff --git a/drivers/staging/iio/adc/ad7793.c b/drivers/staging/iio/adc/ad7793.c
index 843550ddc2ea..ec0fbd43f4ee 100644
--- a/drivers/staging/iio/adc/ad7793.c
+++ b/drivers/staging/iio/adc/ad7793.c
@@ -118,6 +118,12 @@ static int ad7793_setup(struct iio_dev *indio_dev,
 	unsigned long long scale_uv;
 	u32 id;
 
+	if ((pdata->current_source_direction == AD7793_IEXEC1_IEXEC2_IOUT1 ||
+		pdata->current_source_direction == AD7793_IEXEC1_IEXEC2_IOUT2) &&
+		((pdata->exitation_current != AD7793_IX_10uA) &&
+		(pdata->exitation_current != AD7793_IX_210uA)))
+		return -EINVAL;
+
 	/* reset the serial interface */
 	ret = spi_write(st->sd.spi, (u8 *)&ret, sizeof(ret));
 	if (ret < 0)
@@ -136,8 +142,18 @@ static int ad7793_setup(struct iio_dev *indio_dev,
 		goto out;
 	}
 
-	st->mode = pdata->mode;
-	st->conf = pdata->conf;
+	st->mode = AD7793_MODE_RATE(1);
+	st->mode |= AD7793_MODE_CLKSRC(pdata->clock_src);
+	st->conf = AD7793_CONF_REFSEL(pdata->refsel);
+	st->conf |= AD7793_CONF_VBIAS(pdata->bias_voltage);
+	if (pdata->buffered)
+		st->conf |= AD7793_CONF_BUF;
+	if (pdata->boost_enable)
+		st->conf |= AD7793_CONF_BOOST;
+	if (pdata->burnout_current)
+		st->conf |= AD7793_CONF_BO_EN;
+	if (pdata->unipolar)
+		st->conf |= AD7793_CONF_UNIPOLAR;
 
 	ret = ad7793_set_mode(&st->sd, AD_SD_MODE_IDLE);
 	if (ret)
@@ -147,8 +163,9 @@ static int ad7793_setup(struct iio_dev *indio_dev,
 	if (ret)
 		goto out;
 
-	ret = ad_sd_write_reg(&st->sd, AD7793_REG_IO,
-			       sizeof(pdata->io), pdata->io);
+	ret = ad_sd_write_reg(&st->sd, AD7793_REG_IO, 1,
+				   pdata->exitation_current |
+			       (pdata->current_source_direction << 2));
 	if (ret)
 		goto out;
 
diff --git a/drivers/staging/iio/adc/ad7793.h b/drivers/staging/iio/adc/ad7793.h
index 8fdd450a2cd9..9e905906da2f 100644
--- a/drivers/staging/iio/adc/ad7793.h
+++ b/drivers/staging/iio/adc/ad7793.h
@@ -68,7 +68,7 @@
 #define AD7793_CONF_UNIPOLAR	(1 << 12) /* Unipolar/Bipolar Enable */
 #define AD7793_CONF_BOOST	(1 << 11) /* Boost Enable */
 #define AD7793_CONF_GAIN(x)	(((x) & 0x7) << 8) /* Gain Select */
-#define AD7793_CONF_REFSEL	(1 << 7) /* INT/EXT Reference Select */
+#define AD7793_CONF_REFSEL(x)	((x) << 6) /* INT/EXT Reference Select */
 #define AD7793_CONF_BUF		(1 << 4) /* Buffered Mode Enable */
 #define AD7793_CONF_CHAN(x)	((x) & 0xf) /* Channel select */
 #define AD7793_CONF_CHAN_MASK	0xf /* Channel select mask */
@@ -105,11 +105,108 @@
 #define AD7793_IO_IXCEN_210uA	(2 << 0) /* Excitation Current 210uA */
 #define AD7793_IO_IXCEN_1mA	(3 << 0) /* Excitation Current 1mA */
 
+/**
+ * enum ad7793_clock_source - AD7793 clock source selection
+ * @AD7793_CLK_SRC_INT: Internal 64 kHz clock, not available at the CLK pin.
+ * @AD7793_CLK_SRC_INT_CO: Internal 64 kHz clock, available at the CLK pin.
+ * @AD7793_CLK_SRC_EXT: Use external clock.
+ * @AD7793_CLK_SRC_EXT_DIV2: Use external clock divided by 2.
+ */
+enum ad7793_clock_source {
+	AD7793_CLK_SRC_INT,
+	AD7793_CLK_SRC_INT_CO,
+	AD7793_CLK_SRC_EXT,
+	AD7793_CLK_SRC_EXT_DIV2,
+};
+
+/**
+ * enum ad7793_bias_voltage - AD7793 bias voltage selection
+ * @AD7793_BIAS_VOLTAGE_DISABLED: Bias voltage generator disabled
+ * @AD7793_BIAS_VOLTAGE_AIN1: Bias voltage connected to AIN1(-).
+ * @AD7793_BIAS_VOLTAGE_AIN2: Bias voltage connected to AIN2(-).
+ * @AD7793_BIAS_VOLTAGE_AIN3: Bias voltage connected to AIN3(-).
+ *	Only valid for AD7795/AD7796.
+ */
+enum ad7793_bias_voltage {
+	AD7793_BIAS_VOLTAGE_DISABLED,
+	AD7793_BIAS_VOLTAGE_AIN1,
+	AD7793_BIAS_VOLTAGE_AIN2,
+	AD7793_BIAS_VOLTAGE_AIN3,
+};
+
+/**
+ * enum ad7793_refsel - AD7793 reference voltage selection
+ * @AD7793_REFSEL_REFIN1: External reference applied between REFIN1(+)
+ *	and REFIN1(-).
+ * @AD7793_REFSEL_REFIN2: External reference applied between REFIN2(+) and
+ *	and REFIN1(-). Only valid for AD7795/AD7796.
+ * @AD7793_REFSEL_INTERNAL: Internal 1.17 V reference.
+ */
+enum ad7793_refsel {
+	AD7793_REFSEL_REFIN1 = 0,
+	AD7793_REFSEL_REFIN2 = 1,
+	AD7793_REFSEL_INTERNAL = 2,
+};
+
+/**
+ * enum ad7793_current_source_direction - AD7793 excitation current direction
+ * @AD7793_IEXEC1_IOUT1_IEXEC2_IOUT2: Current source IEXC1 connected to pin
+ *	IOUT1, current source IEXC2 connected to pin IOUT2.
+ * @AD7793_IEXEC1_IOUT2_IEXEC2_IOUT1: Current source IEXC2 connected to pin
+ *	IOUT1, current source IEXC1 connected to pin IOUT2.
+ * @AD7793_IEXEC1_IEXEC2_IOUT1: Both current sources connected to pin IOUT1.
+ *	Only valid when the current sources are set to 10 uA or 210 uA.
+ * @AD7793_IEXEC1_IEXEC2_IOUT2: Both current sources connected to Pin IOUT2.
+ *	Only valid when the current ources are set to 10 uA or 210 uA.
+ */
+enum ad7793_current_source_direction {
+	AD7793_IEXEC1_IOUT1_IEXEC2_IOUT2 = 0,
+	AD7793_IEXEC1_IOUT2_IEXEC2_IOUT1 = 1,
+	AD7793_IEXEC1_IEXEC2_IOUT1 = 2,
+	AD7793_IEXEC1_IEXEC2_IOUT2 = 3,
+};
+
+/**
+ * enum ad7793_excitation_current - AD7793 excitation current selection
+ * @AD7793_IX_DISABLED: Excitation current Disabled.
+ * @AD7793_IX_10uA: Enable 10 micro-ampere excitation current.
+ * @AD7793_IX_210uA: Enable 210 micro-ampere excitation current.
+ * @AD7793_IX_1mA: Enable 1 milli-Ampere excitation current.
+ */
+enum ad7793_excitation_current {
+	AD7793_IX_DISABLED = 0,
+	AD7793_IX_10uA = 1,
+	AD7793_IX_210uA = 2,
+	AD7793_IX_1mA = 3,
+};
+
+/**
+ * struct ad7793_platform_data - AD7793 platform data
+ * @vref_mv: Reference voltage in milli-Volt
+ * @clock_src: Clock source selection
+ * @burnout_current: If set to true the 100nA burnout current is enabled.
+ * @boost_enable: Enable boost for the bias voltage generator.
+ * @buffered: If set to true configure the device for buffered input mode.
+ * @unipolar: If set to true sample in unipolar mode, if set to false sample in
+ *		bipolar mode.
+ * @refsel: Reference voltage selection
+ * @bias_voltage: Bias voltage selection
+ * @exitation_current: Excitation current selection
+ * @current_source_direction: Excitation current direction selection
+ */
 struct ad7793_platform_data {
-	u16			vref_mv;
-	u16			mode;
-	u16			conf;
-	u8			io;
+	u16 vref_mv;
+
+	enum ad7793_clock_source clock_src;
+	bool burnout_current;
+	bool boost_enable;
+	bool buffered;
+	bool unipolar;
+
+	enum ad7793_refsel refsel;
+	enum ad7793_bias_voltage bias_voltage;
+	enum ad7793_excitation_current exitation_current;
+	enum ad7793_current_source_direction current_source_direction;
 };
 
 #endif /* IIO_ADC_AD7793_H_ */