[PATCH v2 2/3] iio: frequency: adf4371: add differential ref

[Antoniu Miclaus <antoniu.miclaus@analog.com>]

Add support for differential input reference clock.

Signed-off-by: Antoniu Miclaus <antoniu.miclaus@analog.com>
---
no changes in v2.
 drivers/iio/frequency/adf4371.c | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)

diff --git a/drivers/iio/frequency/adf4371.c b/drivers/iio/frequency/adf4371.c
index b27088464826..55bee06fb42d 100644
--- a/drivers/iio/frequency/adf4371.c
+++ b/drivers/iio/frequency/adf4371.c
@@ -41,6 +41,10 @@
 #define ADF4371_MOD2WORD_MSK		GENMASK(5, 0)
 #define ADF4371_MOD2WORD(x)		FIELD_PREP(ADF4371_MOD2WORD_MSK, x)
 
+/* ADF4371_REG22 */
+#define ADF4371_REFIN_MODE_MASK		BIT(6)
+#define ADF4371_REFIN_MODE(x)		FIELD_PREP(ADF4371_REFIN_MODE_MASK, x)
+
 /* ADF4371_REG24 */
 #define ADF4371_RF_DIV_SEL_MSK		GENMASK(6, 4)
 #define ADF4371_RF_DIV_SEL(x)		FIELD_PREP(ADF4371_RF_DIV_SEL_MSK, x)
@@ -69,6 +73,7 @@
 
 #define ADF4371_MAX_FREQ_PFD		250000000UL /* Hz */
 #define ADF4371_MAX_FREQ_REFIN		600000000UL /* Hz */
+#define ADF4371_MAX_FREQ_REFIN_SE	500000000UL /* Hz */
 
 /* MOD1 is a 24-bit primary modulus with fixed value of 2^25 */
 #define ADF4371_MODULUS1		33554432ULL
@@ -476,6 +481,7 @@ static int adf4371_setup(struct adf4371_state *st)
 {
 	unsigned int synth_timeout = 2, timeout = 1, vco_alc_timeout = 1;
 	unsigned int vco_band_div, tmp;
+	bool ref_diff_en;
 	int ret;
 
 	/* Perform a software reset */
@@ -497,12 +503,25 @@ static int adf4371_setup(struct adf4371_state *st)
 			return ret;
 	}
 
+	ref_diff_en = device_property_read_bool(&st->spi->dev, "adi,ref-differential-enable");
+
 	/* Set address in ascending order, so the bulk_write() will work */
 	ret = regmap_update_bits(st->regmap, ADF4371_REG(0x0),
 				 ADF4371_ADDR_ASC_MSK | ADF4371_ADDR_ASC_R_MSK,
 				 ADF4371_ADDR_ASC(1) | ADF4371_ADDR_ASC_R(1));
 	if (ret < 0)
 		return ret;
+
+	if ((ref_diff_en && st->clkin_freq > ADF4371_MAX_FREQ_REFIN) ||
+	    (!ref_diff_en && st->clkin_freq > ADF4371_MAX_FREQ_REFIN_SE))
+		return -EINVAL;
+
+	ret = regmap_update_bits(st->regmap,  ADF4371_REG(0x22),
+				 ADF4371_REFIN_MODE_MASK,
+				 ADF4371_REFIN_MODE(ref_diff_en));
+	if (ret < 0)
+		return ret;
+
 	/*
 	 * Calculate and maximize PFD frequency
 	 * fPFD = REFIN × ((1 + D)/(R × (1 + T)))
-- 
2.47.1