Merge tag 'iio-fixes-for-4.4a' of ssh://ra.kernel.org/pub/scm/linux/kernel/git/jic23/iio into staging-linus

Jonathan writes:

First set of IIO fixes for the 4.4 cycle.

This set does not include those for issues introduced during the merge
window.  Fixes of those will follow in a future series.

* ad5064
  - Make sure the local i2c_write returns 0 on success rather than the
    number of bytes transfered.  Otherwise we report an error on all writes.
  - Fix a shift for ad5629 and ad5669 which gives incorrect DAC output on
    these parts.
* ad7793
  - The product ID on the datasheet is wrong.  Fix it in the driver.
* IIO_DUMMY_EVGEN
  - select IRQ_WORK as a dependency.
* lpc32xx
  - make sure clock is prepared before enabling.
* si7020
  - data byte order was reversed. Fix it.
* vf610
  - Internal temperature calculation was wrong if a different
    reference voltage was used.  Now use a linear interpolation
    function to make it work over the full range.
  - Fix a division by zero in the case of a device tree property
    not being present (same issue two fixes).
* xilinx XADC
  - VREFN scale was wrong - fix it.

1 files changed, 16 insertions, 6 deletions

diff --git a/drivers/iio/adc/vf610_adc.c b/drivers/iio/adc/vf610_adc.c
index 599cde3d03a1..b10f629cc44b 100644
--- a/drivers/iio/adc/vf610_adc.c
+++ b/drivers/iio/adc/vf610_adc.c
@@ -106,6 +106,13 @@
 
 #define DEFAULT_SAMPLE_TIME		1000
 
+/* V at 25°C of 696 mV */
+#define VF610_VTEMP25_3V0		950
+/* V at 25°C of 699 mV */
+#define VF610_VTEMP25_3V3		867
+/* Typical sensor slope coefficient at all temperatures */
+#define VF610_TEMP_SLOPE_COEFF		1840
+
 enum clk_sel {
 	VF610_ADCIOC_BUSCLK_SET,
 	VF610_ADCIOC_ALTCLK_SET,
@@ -197,6 +204,8 @@ static inline void vf610_adc_calculate_rates(struct vf610_adc *info)
 		adc_feature->clk_div = 8;
 	}
 
+	adck_rate = ipg_rate / adc_feature->clk_div;
+
 	/*
 	 * Determine the long sample time adder value to be used based
 	 * on the default minimum sample time provided.
@@ -221,7 +230,6 @@ static inline void vf610_adc_calculate_rates(struct vf610_adc *info)
 	 * BCT (Base Conversion Time): fixed to 25 ADCK cycles for 12 bit mode
 	 * LSTAdder(Long Sample Time): 3, 5, 7, 9, 13, 17, 21, 25 ADCK cycles
 	 */
-	adck_rate = ipg_rate / info->adc_feature.clk_div;
 	for (i = 0; i < ARRAY_SIZE(vf610_hw_avgs); i++)
 		info->sample_freq_avail[i] =
 			adck_rate / (6 + vf610_hw_avgs[i] *
@@ -663,11 +671,13 @@ static int vf610_read_raw(struct iio_dev *indio_dev,
 			break;
 		case IIO_TEMP:
 			/*
-			* Calculate in degree Celsius times 1000
-			* Using sensor slope of 1.84 mV/°C and
-			* V at 25°C of 696 mV
-			*/
-			*val = 25000 - ((int)info->value - 864) * 1000000 / 1840;
+			 * Calculate in degree Celsius times 1000
+			 * Using the typical sensor slope of 1.84 mV/°C
+			 * and VREFH_ADC at 3.3V, V at 25°C of 699 mV
+			 */
+			*val = 25000 - ((int)info->value - VF610_VTEMP25_3V3) *
+					1000000 / VF610_TEMP_SLOPE_COEFF;
+
 			break;
 		default:
 			mutex_unlock(&indio_dev->mlock);