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From:   David Lechner <dlechner@baylibre.com>
To:     linux-iio@vger.kernel.org, devicetree@vger.kernel.org,
        linux-staging@lists.linux.dev
Cc:     linux-kernel@vger.kernel.org, Jonathan Cameron <jic23@kernel.org>,
        Rob Herring <robh+dt@kernel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
        Conor Dooley <conor+dt@kernel.org>,
        Michael Hennerich <Michael.Hennerich@analog.com>,
        =?UTF-8?q?Nuno=20S=C3=A1?= <nuno.sa@analog.com>,
        Axel Haslam <ahaslam@baylibre.com>,
        Philip Molloy <pmolloy@baylibre.com>,
        David Lechner <dlechner@baylibre.com>
Subject: [PATCH v2 07/19] staging: iio: resolver: ad2s1210: implement IIO_CHAN_INFO_SCALE
Date:   Thu, 21 Sep 2023 09:43:48 -0500
Message-Id: <20230921144400.62380-8-dlechner@baylibre.com>
In-Reply-To: <20230921144400.62380-1-dlechner@baylibre.com>
References: <20230921144400.62380-1-dlechner@baylibre.com>
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This adds an implementation of IIO_CHAN_INFO_SCALE to the ad2s1210
resolver driver. This allows userspace to get the scale factor for the
raw values.

Signed-off-by: David Lechner <dlechner@baylibre.com>
---
 drivers/staging/iio/resolver/ad2s1210.c | 107 ++++++++++++++++--------
 1 file changed, 72 insertions(+), 35 deletions(-)

diff --git a/drivers/staging/iio/resolver/ad2s1210.c b/drivers/staging/iio/resolver/ad2s1210.c
index 985b8fecd65a..95d43b241a75 100644
--- a/drivers/staging/iio/resolver/ad2s1210.c
+++ b/drivers/staging/iio/resolver/ad2s1210.c
@@ -458,56 +458,91 @@ static ssize_t ad2s1210_store_reg(struct device *dev,
 	return ret < 0 ? ret : len;
 }
 
+static const int ad2s1210_velocity_scale[] = {
+	17089132, /* 8.192MHz / (2*pi * 2500 / 2^15) */
+	42722830, /* 8.192MHz / (2*pi * 1000 / 2^15) */
+	85445659, /* 8.192MHz / (2*pi * 500 / 2^15) */
+	341782638, /* 8.192MHz / (2*pi * 125 / 2^15) */
+};
+
 static int ad2s1210_read_raw(struct iio_dev *indio_dev,
 			     struct iio_chan_spec const *chan,
 			     int *val,
 			     int *val2,
-			     long m)
+			     long mask)
 {
 	struct ad2s1210_state *st = iio_priv(indio_dev);
 	int ret = 0;
 
-	mutex_lock(&st->lock);
-	gpiod_set_value(st->gpios[AD2S1210_SAMPLE], 0);
-	/* delay (6 * tck + 20) nano seconds */
-	udelay(1);
+	switch (mask) {
+	case IIO_CHAN_INFO_RAW:
+		mutex_lock(&st->lock);
+		gpiod_set_value(st->gpios[AD2S1210_SAMPLE], 0);
+		/* delay (6 * tck + 20) nano seconds */
+		udelay(1);
+
+		switch (chan->type) {
+		case IIO_ANGL:
+			ad2s1210_set_mode(MOD_POS, st);
+			break;
+		case IIO_ANGL_VEL:
+			ad2s1210_set_mode(MOD_VEL, st);
+			break;
+		default:
+			ret = -EINVAL;
+			break;
+		}
+		if (ret < 0)
+			goto error_info_raw;
+		ret = spi_read(st->sdev, st->rx, 2);
+		if (ret < 0)
+			goto error_info_raw;
+
+		switch (chan->type) {
+		case IIO_ANGL:
+			*val = be16_to_cpup((__be16 *)st->rx);
+			ret = IIO_VAL_INT;
+			break;
+		case IIO_ANGL_VEL:
+			*val = (s16)be16_to_cpup((__be16 *)st->rx);
+			ret = IIO_VAL_INT;
+			break;
+		default:
+			ret = -EINVAL;
+			break;
+		}
 
-	switch (chan->type) {
-	case IIO_ANGL:
-		ad2s1210_set_mode(MOD_POS, st);
-		break;
-	case IIO_ANGL_VEL:
-		ad2s1210_set_mode(MOD_VEL, st);
-		break;
-	default:
-		ret = -EINVAL;
+error_info_raw:
+		gpiod_set_value(st->gpios[AD2S1210_SAMPLE], 1);
+		/* delay (2 * tck + 20) nano seconds */
+		udelay(1);
+		mutex_unlock(&st->lock);
 		break;
-	}
-	if (ret < 0)
-		goto error_ret;
-	ret = spi_read(st->sdev, st->rx, 2);
-	if (ret < 0)
-		goto error_ret;
 
-	switch (chan->type) {
-	case IIO_ANGL:
-		*val = be16_to_cpup((__be16 *)st->rx);
-		ret = IIO_VAL_INT;
-		break;
-	case IIO_ANGL_VEL:
-		*val = (s16)be16_to_cpup((__be16 *)st->rx);
-		ret = IIO_VAL_INT;
+	case IIO_CHAN_INFO_SCALE:
+		switch (chan->type) {
+		case IIO_ANGL:
+			/* approx 0.3 arc min converted to radians */
+			*val = 0;
+			*val2 = 95874;
+			ret = IIO_VAL_INT_PLUS_NANO;
+			break;
+		case IIO_ANGL_VEL:
+			*val = st->fclkin;
+			*val2 = ad2s1210_velocity_scale[st->resolution];
+			ret = IIO_VAL_FRACTIONAL;
+			break;
+		default:
+			ret = -EINVAL;
+			break;
+		}
 		break;
+
 	default:
 		ret = -EINVAL;
 		break;
 	}
 
-error_ret:
-	gpiod_set_value(st->gpios[AD2S1210_SAMPLE], 1);
-	/* delay (2 * tck + 20) nano seconds */
-	udelay(1);
-	mutex_unlock(&st->lock);
 	return ret;
 }
 
@@ -549,12 +584,14 @@ static const struct iio_chan_spec ad2s1210_channels[] = {
 		.type = IIO_ANGL,
 		.indexed = 1,
 		.channel = 0,
-		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
+		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
+				      BIT(IIO_CHAN_INFO_SCALE),
 	}, {
 		.type = IIO_ANGL_VEL,
 		.indexed = 1,
 		.channel = 0,
-		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
+		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
+				      BIT(IIO_CHAN_INFO_SCALE),
 	}
 };
 
-- 
2.34.1