[PATCH v6 3/3] iio: frequency: adf4371: add ref doubler

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

Add support for the reference doubler.

Reviewed-by: Nuno Sa <nuno.sa@analog.com>
Signed-off-by: Antoniu Miclaus <antoniu.miclaus@analog.com>
---
changes in v6:
 - rebase with latest version and resolve conflicts.
 drivers/iio/frequency/adf4371.c | 16 ++++++++++++++--
 1 file changed, 14 insertions(+), 2 deletions(-)

diff --git a/drivers/iio/frequency/adf4371.c b/drivers/iio/frequency/adf4371.c
index 205dfd341489..55516ececb23 100644
--- a/drivers/iio/frequency/adf4371.c
+++ b/drivers/iio/frequency/adf4371.c
@@ -45,6 +45,8 @@
 /* ADF4371_REG22 */
 #define ADF4371_REFIN_MODE_MASK		BIT(6)
 #define ADF4371_REFIN_MODE(x)		FIELD_PREP(ADF4371_REFIN_MODE_MASK, x)
+#define ADF4371_REF_DOUB_MASK		BIT(5)
+#define ADF4371_REF_DOUB(x)		FIELD_PREP(ADF4371_REF_DOUB_MASK, x)\
 
 /* ADF4371_REG24 */
 #define ADF4371_RF_DIV_SEL_MSK		GENMASK(6, 4)
@@ -76,6 +78,9 @@
 #define ADF4371_MAX_FREQ_REFIN		600000000UL /* Hz */
 #define ADF4371_MAX_FREQ_REFIN_SE	500000000UL /* Hz */
 
+#define ADF4371_MIN_CLKIN_DOUB_FREQ	10000000ULL /* Hz */
+#define ADF4371_MAX_CLKIN_DOUB_FREQ	125000000ULL /* Hz */
+
 /* MOD1 is a 24-bit primary modulus with fixed value of 2^25 */
 #define ADF4371_MODULUS1		33554432ULL
 /* MOD2 is the programmable, 14-bit auxiliary fractional modulus */
@@ -483,7 +488,7 @@ static const struct iio_info adf4371_info = {
 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;
+	unsigned int vco_band_div, tmp, ref_doubler_en = 0;
 	int ret;
 
 	/* Perform a software reset */
@@ -516,8 +521,14 @@ static int adf4371_setup(struct adf4371_state *st)
 	    (!st->ref_diff_en && st->clkin_freq > ADF4371_MAX_FREQ_REFIN_SE))
 		return -EINVAL;
 
+	if (st->clkin_freq < ADF4371_MAX_CLKIN_DOUB_FREQ &&
+	    st->clkin_freq > ADF4371_MIN_CLKIN_DOUB_FREQ)
+		ref_doubler_en = 1;
+
 	ret = regmap_update_bits(st->regmap,  ADF4371_REG(0x22),
+				 ADF4371_REF_DOUB_MASK |
 				 ADF4371_REFIN_MODE_MASK,
+				 ADF4371_REF_DOUB(ref_doubler_en) |
 				 ADF4371_REFIN_MODE(st->ref_diff_en));
 	if (ret < 0)
 		return ret;
@@ -531,7 +542,8 @@ static int adf4371_setup(struct adf4371_state *st)
 	 */
 	do {
 		st->ref_div_factor++;
-		st->fpfd = st->clkin_freq / st->ref_div_factor;
+		st->fpfd = st->clkin_freq * (1 + ref_doubler_en) /
+			   st->ref_div_factor;
 	} while (st->fpfd > ADF4371_MAX_FREQ_PFD);
 
 	/* Calculate Timeouts */
-- 
2.48.1