[PATCH RFC v2 6/9] iio: frequency: ad9910: add output shift keying support

[Rodrigo Alencar via B4 Relay <devnull+rodrigo.alencar.analog.com@kernel.org>]

From: Rodrigo Alencar <rodrigo.alencar@analog.com>

Add OSK channel with amplitude envelope control capabilities:
- OSK enable/disable via IIO_CHAN_INFO_ENABLE;
- Amplitude ramp rate control via IIO_CHAN_INFO_SAMP_FREQ;
- Amplitude scale readback via IIO_CHAN_INFO_SCALE (ASF register);
- Manual/external pin control via pinctrl_en ext_info attribute;
- Automatic OSK step size configuration via scale_increment ext_info;
  attribute with selectable step sizes (61, 122, 244, 488 micro-units)

The ASF register is initialized with a default amplitude ramp rate during
device setup to ensure valid readback.

Signed-off-by: Rodrigo Alencar <rodrigo.alencar@analog.com>
---
 drivers/iio/frequency/ad9910.c | 152 ++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 151 insertions(+), 1 deletion(-)

diff --git a/drivers/iio/frequency/ad9910.c b/drivers/iio/frequency/ad9910.c
index 747f4f407536..35572d60d6d2 100644
--- a/drivers/iio/frequency/ad9910.c
+++ b/drivers/iio/frequency/ad9910.c
@@ -232,6 +232,7 @@
  * @AD9910_CHANNEL_DRG_RAMP_UP: DRG ramp up channel
  * @AD9910_CHANNEL_DRG_RAMP_DOWN: DRG ramp down channel
  * @AD9910_CHANNEL_RAM: RAM control output channel
+ * @AD9910_CHANNEL_OSK: Output Shift Keying output channel
  */
 enum ad9910_channel {
 	AD9910_CHANNEL_PHY = 100,
@@ -241,6 +242,7 @@ enum ad9910_channel {
 	AD9910_CHANNEL_DRG_RAMP_UP = 131,
 	AD9910_CHANNEL_DRG_RAMP_DOWN = 132,
 	AD9910_CHANNEL_RAM = 140,
+	AD9910_CHANNEL_OSK = 150,
 };
 
 /**
@@ -317,6 +319,8 @@ enum {
 	AD9910_DRG_AMP_STEP,
 	AD9910_RAM_START_ADDR,
 	AD9910_RAM_END_ADDR,
+	AD9910_OSK_MANUAL_EXTCTL,
+	AD9910_OSK_AUTO_STEP,
 };
 
 struct ad9910_data {
@@ -405,6 +409,10 @@ static const char * const ad9910_ram_oper_mode_str[] = {
 	[AD9910_RAM_MODE_SEQ_CONT] = "sequenced_continuous",
 };
 
+static const u16 ad9910_osk_ustep[] = {
+	0, 61, 122, 244, 488,
+};
+
 /**
  * ad9910_rational_scale() - Perform scaling of input given a reference.
  * @input: The input value to be scaled.
@@ -802,6 +810,10 @@ static ssize_t ad9910_ext_info_read(struct iio_dev *indio_dev,
 		val = FIELD_GET(AD9910_PROFILE_RAM_END_ADDR_MSK,
 				ad9910_ram_profile_val(st));
 		break;
+	case AD9910_OSK_MANUAL_EXTCTL:
+		val = FIELD_GET(AD9910_CFR1_OSK_MANUAL_EXT_CTL_MSK,
+				st->reg[AD9910_REG_CFR1].val32);
+		break;
 	default:
 		return -EINVAL;
 	}
@@ -873,6 +885,12 @@ static ssize_t ad9910_ext_info_write(struct iio_dev *indio_dev,
 		FIELD_MODIFY(AD9910_PROFILE_RAM_END_ADDR_MSK,
 			     &st->reg_profile[st->profile], val32);
 		break;
+	case AD9910_OSK_MANUAL_EXTCTL:
+		val32 = val32 ? AD9910_CFR1_OSK_MANUAL_EXT_CTL_MSK : 0;
+		ret = ad9910_reg32_update(st, AD9910_REG_CFR1,
+					  AD9910_CFR1_OSK_MANUAL_EXT_CTL_MSK,
+					  val32, true);
+		break;
 	default:
 		return -EINVAL;
 	}
@@ -1105,6 +1123,80 @@ static ssize_t ad9910_drg_attrs_write(struct iio_dev *indio_dev,
 	return ret ?: len;
 }
 
+static ssize_t ad9910_osk_attrs_read(struct iio_dev *indio_dev,
+				     uintptr_t private,
+				     const struct iio_chan_spec *chan,
+				     char *buf)
+{
+	struct ad9910_state *st = iio_priv(indio_dev);
+	int vals[2];
+	bool auto_en;
+	u32 raw_val;
+
+	guard(mutex)(&st->lock);
+
+	switch (private) {
+	case AD9910_OSK_AUTO_STEP:
+		auto_en = FIELD_GET(AD9910_CFR1_SELECT_AUTO_OSK_MSK,
+				    st->reg[AD9910_REG_CFR1].val32);
+		raw_val = FIELD_GET(AD9910_ASF_STEP_SIZE_MSK,
+				    st->reg[AD9910_REG_ASF].val32);
+		vals[0] = 0;
+		vals[1] = auto_en ? ad9910_osk_ustep[raw_val + 1] : 0;
+
+		return iio_format_value(buf, IIO_VAL_INT_PLUS_MICRO, 2, vals);
+	default:
+		return -EINVAL;
+	}
+}
+
+static ssize_t ad9910_osk_attrs_write(struct iio_dev *indio_dev,
+				      uintptr_t private,
+				      const struct iio_chan_spec *chan,
+				      const char *buf, size_t len)
+{
+	struct ad9910_state *st = iio_priv(indio_dev);
+	int val, val2;
+	int ret;
+	u32 raw_val;
+
+	ret = iio_str_to_fixpoint(buf, MICRO / 10, &val, &val2);
+	if (ret)
+		return ret;
+
+	guard(mutex)(&st->lock);
+
+	switch (private) {
+	case AD9910_OSK_AUTO_STEP:
+		if (val != 0)
+			return -EINVAL;
+
+		raw_val = find_closest(val2, ad9910_osk_ustep,
+				       ARRAY_SIZE(ad9910_osk_ustep));
+		if (raw_val) {
+			/* set OSK step and get automatic OSK enabled */
+			raw_val = FIELD_PREP(AD9910_ASF_STEP_SIZE_MSK,
+					     raw_val - 1);
+			ret = ad9910_reg32_update(st, AD9910_REG_ASF,
+						  AD9910_ASF_STEP_SIZE_MSK,
+						  raw_val, true);
+			if (ret)
+				return ret;
+
+			raw_val = AD9910_CFR1_SELECT_AUTO_OSK_MSK;
+		}
+
+		ret = ad9910_reg32_update(st, AD9910_REG_CFR1,
+					  AD9910_CFR1_SELECT_AUTO_OSK_MSK,
+					  raw_val, true);
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	return ret ?: len;
+}
+
 #define AD9910_EXT_INFO_TMPL(_name, _ident, _shared, _fn_desc) { \
 	.name = _name, \
 	.read = ad9910_ ## _fn_desc ## _read, \
@@ -1122,6 +1214,9 @@ static ssize_t ad9910_drg_attrs_write(struct iio_dev *indio_dev,
 #define AD9910_DRG_EXT_INFO(_name, _ident) \
 	AD9910_EXT_INFO_TMPL(_name, _ident, IIO_SEPARATE, drg_attrs)
 
+#define AD9910_OSK_EXT_INFO(_name, _ident) \
+	AD9910_EXT_INFO_TMPL(_name, _ident, IIO_SEPARATE, osk_attrs)
+
 static const struct iio_enum ad9910_drg_destination_enum = {
 	.items = ad9910_destination_str,
 	.num_items = AD9910_DRG_DEST_NUM,
@@ -1189,6 +1284,12 @@ static const struct iio_chan_spec_ext_info ad9910_ram_ext_info[] = {
 	{ }
 };
 
+static const struct iio_chan_spec_ext_info ad9910_osk_ext_info[] = {
+	AD9910_EXT_INFO("pinctrl_en", AD9910_OSK_MANUAL_EXTCTL, IIO_SEPARATE),
+	AD9910_OSK_EXT_INFO("scale_step", AD9910_OSK_AUTO_STEP),
+	{ }
+};
+
 static const struct iio_chan_spec ad9910_channels[] = {
 	[AD9910_CHAN_IDX_PHY] = {
 		.type = IIO_ALTVOLTAGE,
@@ -1269,6 +1370,18 @@ static const struct iio_chan_spec ad9910_channels[] = {
 				      BIT(IIO_CHAN_INFO_SAMP_FREQ),
 		.ext_info = ad9910_ram_ext_info,
 	},
+	[AD9910_CHAN_IDX_OSK] = {
+		.type = IIO_ALTVOLTAGE,
+		.indexed = 1,
+		.output = 1,
+		.channel = AD9910_CHANNEL_OSK,
+		.address = AD9910_CHAN_IDX_OSK,
+		.scan_index = -1,
+		.info_mask_separate = BIT(IIO_CHAN_INFO_ENABLE) |
+				      BIT(IIO_CHAN_INFO_SCALE) |
+				      BIT(IIO_CHAN_INFO_SAMP_FREQ),
+		.ext_info = ad9910_osk_ext_info,
+	},
 };
 
 static int ad9910_read_raw(struct iio_dev *indio_dev,
@@ -1296,6 +1409,10 @@ static int ad9910_read_raw(struct iio_dev *indio_dev,
 			*val = FIELD_GET(AD9910_CFR1_RAM_ENABLE_MSK,
 					 st->reg[AD9910_REG_CFR1].val32);
 			break;
+		case AD9910_CHANNEL_OSK:
+			*val = FIELD_GET(AD9910_CFR1_OSK_ENABLE_MSK,
+					 st->reg[AD9910_REG_CFR1].val32);
+			break;
 		default:
 			return -EINVAL;
 		}
@@ -1374,6 +1491,12 @@ static int ad9910_read_raw(struct iio_dev *indio_dev,
 			*val = 0;
 			*val2 = tmp64 * NANO >> 32;
 			return IIO_VAL_INT_PLUS_NANO;
+		case AD9910_CHANNEL_OSK:
+			tmp64 = FIELD_GET(AD9910_ASF_SCALE_FACTOR_MSK,
+					  st->reg[AD9910_REG_ASF].val32);
+			*val = 0;
+			*val2 = tmp64 * MICRO >> 14;
+			return IIO_VAL_INT_PLUS_MICRO;
 		default:
 			return -EINVAL;
 		}
@@ -1394,6 +1517,10 @@ static int ad9910_read_raw(struct iio_dev *indio_dev,
 			tmp32 = FIELD_GET(AD9910_PROFILE_RAM_STEP_RATE_MSK,
 					  ad9910_ram_profile_val(st));
 			break;
+		case AD9910_CHANNEL_OSK:
+			tmp32 = FIELD_GET(AD9910_ASF_RAMP_RATE_MSK,
+					  st->reg[AD9910_REG_ASF].val32);
+			break;
 		default:
 			return -EINVAL;
 		}
@@ -1453,6 +1580,11 @@ static int ad9910_write_raw(struct iio_dev *indio_dev,
 			return ad9910_reg32_update(st, AD9910_REG_CFR1,
 						   AD9910_CFR1_RAM_ENABLE_MSK,
 						   tmp32, true);
+		case AD9910_CHANNEL_OSK:
+			tmp32 = FIELD_PREP(AD9910_CFR1_OSK_ENABLE_MSK, val);
+			return ad9910_reg32_update(st, AD9910_REG_CFR1,
+						   AD9910_CFR1_OSK_ENABLE_MSK,
+						   tmp32, true);
 		default:
 			return -EINVAL;
 		}
@@ -1585,6 +1717,14 @@ static int ad9910_write_raw(struct iio_dev *indio_dev,
 			return ad9910_reg64_update(st, AD9910_REG_DRG_LIMIT,
 						   AD9910_DRG_LIMIT_LOWER_MSK,
 						   tmp64, true);
+		case AD9910_CHANNEL_OSK:
+			tmp64 = ((u64)val * MICRO + val2) << 14;
+			tmp64 = DIV_U64_ROUND_CLOSEST(tmp64, MICRO);
+			tmp32 = min(tmp64, AD9910_ASF_MAX);
+			tmp32 = FIELD_PREP(AD9910_ASF_SCALE_FACTOR_MSK, tmp32);
+			return ad9910_reg32_update(st, AD9910_REG_ASF,
+						   AD9910_ASF_SCALE_FACTOR_MSK,
+						   tmp32, true);
 		default:
 			return -EINVAL;
 		}
@@ -1621,7 +1761,12 @@ static int ad9910_write_raw(struct iio_dev *indio_dev,
 			return ad9910_reg64_update(st, AD9910_REG_PROFILE(st->profile),
 						   AD9910_PROFILE_RAM_STEP_RATE_MSK,
 						   tmp64, true);
-
+			break;
+		case AD9910_CHANNEL_OSK:
+			return ad9910_reg32_update(st, AD9910_REG_ASF,
+						   AD9910_ASF_RAMP_RATE_MSK,
+						   FIELD_PREP(AD9910_ASF_RAMP_RATE_MSK, tmp32),
+						   true);
 		default:
 			return -EINVAL;
 		}
@@ -1916,6 +2061,11 @@ static int ad9910_setup(struct ad9910_state *st, struct reset_control *dev_rst)
 		return ret;
 
 	/* configure step rate with default values */
+	reg32 = FIELD_PREP(AD9910_ASF_RAMP_RATE_MSK, 1);
+	ret = ad9910_reg32_write(st, AD9910_REG_ASF, reg32, false);
+	if (ret)
+		return ret;
+
 	reg32 = FIELD_PREP(AD9910_DRG_RATE_DEC_MSK, 1) |
 		FIELD_PREP(AD9910_DRG_RATE_INC_MSK, 1);
 	ret = ad9910_reg32_write(st, AD9910_REG_DRG_RATE, reg32, false);

-- 
2.43.0