iio: adc: at91-sama5d2_adc: update trackx on emr

Add support for updating trackx bits of EMR register. Having different
values of EMR.TRACKX when measuring temperature give a better accuracy.

Signed-off-by: Claudiu Beznea <claudiu.beznea@microchip.com>
Link: https://lore.kernel.org/r/20220803102855.2191070-14-claudiu.beznea@microchip.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

diff --git a/drivers/iio/adc/at91-sama5d2_adc.c b/drivers/iio/adc/at91-sama5d2_adc.c
index a1df475..0209353 100644 (file)
--- a/drivers/iio/adc/at91-sama5d2_adc.c
+++ b/drivers/iio/adc/at91-sama5d2_adc.c
@@ -145,6 +145,10 @@ struct at91_adc_reg_layout {
 #define AT91_SAMA5D2_EMR_OSR_64SAMPLES         3
 #define AT91_SAMA5D2_EMR_OSR_256SAMPLES                4
 
+/* Extended Mode Register - TRACKX */
+#define AT91_SAMA5D2_TRACKX_MASK               GENMASK(23, 22)
+#define AT91_SAMA5D2_TRACKX(x)                 (((x) << 22) & \
+                                                AT91_SAMA5D2_TRACKX_MASK)
 /* Extended Mode Register - Averaging on single trigger event */
 #define AT91_SAMA5D2_EMR_ASTE(V)               ((V) << 20)
 
@@ -746,7 +750,7 @@ static void at91_adc_eoc_ena(struct at91_adc_state *st, unsigned int channel)
 }
 
 static int at91_adc_config_emr(struct at91_adc_state *st,
-                              u32 oversampling_ratio)
+                              u32 oversampling_ratio, u32 trackx)
 {
        /* configure the extended mode register */
        unsigned int emr = at91_adc_readl(st, EMR);
@@ -765,7 +769,7 @@ static int at91_adc_config_emr(struct at91_adc_state *st,
        emr |= AT91_SAMA5D2_EMR_ASTE(1);
 
        /* delete leftover content if it's the case */
-       emr &= ~osr_mask;
+       emr &= ~(osr_mask | AT91_SAMA5D2_TRACKX_MASK);
 
        /* select oversampling ratio from configuration */
        switch (oversampling_ratio) {
@@ -791,6 +795,8 @@ static int at91_adc_config_emr(struct at91_adc_state *st,
                break;
        }
 
+       /* Update trackx. */
+       emr |= AT91_SAMA5D2_TRACKX(trackx);
        at91_adc_writel(st, EMR, emr);
 
        st->oversampling_ratio = oversampling_ratio;
@@ -1706,7 +1712,7 @@ static int at91_adc_write_raw(struct iio_dev *indio_dev,
                        return ret;
                mutex_lock(&st->lock);
                /* update ratio */
-               ret = at91_adc_config_emr(st, val);
+               ret = at91_adc_config_emr(st, val, 0);
                mutex_unlock(&st->lock);
                iio_device_release_direct_mode(indio_dev);
                return ret;
@@ -1904,7 +1910,7 @@ static void at91_adc_hw_init(struct iio_dev *indio_dev)
        at91_adc_setup_samp_freq(indio_dev, st->soc_info.min_sample_rate);
 
        /* configure extended mode register */
-       at91_adc_config_emr(st, st->oversampling_ratio);
+       at91_adc_config_emr(st, st->oversampling_ratio, 0);
 }
 
 static ssize_t at91_adc_get_fifo_state(struct device *dev,