linux-kernel - [PATCH v2 19/19] staging: iio: resolver: ad2s1210: add triggered buffer support

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Date:   Thu, 21 Sep 2023 09:44:00 -0500
From:   David Lechner <dlechner@...libre.com>
To:     linux-iio@...r.kernel.org, devicetree@...r.kernel.org,
        linux-staging@...ts.linux.dev
Cc:     linux-kernel@...r.kernel.org, Jonathan Cameron <jic23@...nel.org>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Conor Dooley <conor+dt@...nel.org>,
        Michael Hennerich <Michael.Hennerich@...log.com>,
        Nuno Sá <nuno.sa@...log.com>,
        Axel Haslam <ahaslam@...libre.com>,
        Philip Molloy <pmolloy@...libre.com>,
        David Lechner <dlechner@...libre.com>
Subject: [PATCH v2 19/19] staging: iio: resolver: ad2s1210: add triggered buffer support

This adds support for triggered buffers to the AD2S1210 resolver driver.

Signed-off-by: David Lechner <dlechner@...libre.com>
---
 drivers/staging/iio/resolver/ad2s1210.c | 84 ++++++++++++++++++++++++-
 1 file changed, 83 insertions(+), 1 deletion(-)

diff --git a/drivers/staging/iio/resolver/ad2s1210.c b/drivers/staging/iio/resolver/ad2s1210.c
index f5b8b290e860..44a2ecaeeeff 100644
--- a/drivers/staging/iio/resolver/ad2s1210.c
+++ b/drivers/staging/iio/resolver/ad2s1210.c
@@ -19,8 +19,11 @@
 #include <linux/sysfs.h>
 #include <linux/types.h>
 
+#include <linux/iio/buffer.h>
 #include <linux/iio/iio.h>
 #include <linux/iio/sysfs.h>
+#include <linux/iio/trigger_consumer.h>
+#include <linux/iio/triggered_buffer.h>
 
 #define DRV_NAME "ad2s1210"
 
@@ -85,6 +88,12 @@ struct ad2s1210_state {
 	unsigned long fclkin;
 	/** The selected resolution */
 	enum ad2s1210_resolution resolution;
+	/** Scan buffer */
+	struct {
+		__be16 chan[2];
+		/* Ensure timestamp is naturally aligned. */
+		s64 timestamp __aligned(8);
+	} scan;
 	u8 rx[2] __aligned(IIO_DMA_MINALIGN);
 	u8 tx[2];
 };
@@ -592,18 +601,35 @@ static const struct iio_chan_spec ad2s1210_channels[] = {
 		.type = IIO_ANGL,
 		.indexed = 1,
 		.channel = 0,
+		.scan_index = 0,
+		.scan_type = {
+			.sign = 'u',
+			.realbits = 16,
+			.storagebits = 16,
+			.endianness = IIO_BE,
+		},
 		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
 				      BIT(IIO_CHAN_INFO_SCALE) |
 				      BIT(IIO_CHAN_INFO_HYSTERESIS),
 		.info_mask_separate_available =
 					BIT(IIO_CHAN_INFO_HYSTERESIS),
+		.datasheet_name = "position",
 	}, {
 		.type = IIO_ANGL_VEL,
 		.indexed = 1,
 		.channel = 0,
+		.scan_index = 1,
+		.scan_type = {
+			.sign = 's',
+			.realbits = 16,
+			.storagebits = 16,
+			.endianness = IIO_BE,
+		},
 		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
 				      BIT(IIO_CHAN_INFO_SCALE),
-	}
+		.datasheet_name = "velocity",
+	},
+	IIO_CHAN_SOFT_TIMESTAMP(2),
 };
 
 static struct attribute *ad2s1210_attributes[] = {
@@ -665,6 +691,55 @@ static int ad2s1210_debugfs_reg_access(struct iio_dev *indio_dev,
 	return ret;
 }
 
+static irqreturn_t ad2s1210_trigger_handler(int irq, void *p)
+{
+	struct iio_poll_func *pf = p;
+	struct iio_dev *indio_dev = pf->indio_dev;
+	struct ad2s1210_state *st = iio_priv(indio_dev);
+	size_t chan = 0;
+	int ret;
+
+	mutex_lock(&st->lock);
+
+	memset(&st->scan, 0, sizeof(st->scan));
+	gpiod_set_value(st->sample_gpio, 1);
+
+	if (test_bit(0, indio_dev->active_scan_mask)) {
+		ret = ad2s1210_set_mode(st, MOD_POS);
+		if (ret < 0)
+			goto error_ret;
+
+		/* REVIST: we can read 3 bytes here and also get fault flags */
+		ret = spi_read(st->sdev, st->rx, 2);
+		if (ret < 0)
+			goto error_ret;
+
+		memcpy(&st->scan.chan[chan++], st->rx, 2);
+	}
+
+	if (test_bit(1, indio_dev->active_scan_mask)) {
+		ret = ad2s1210_set_mode(st, MOD_VEL);
+		if (ret < 0)
+			goto error_ret;
+
+		/* REVIST: we can read 3 bytes here and also get fault flags */
+		ret = spi_read(st->sdev, st->rx, 2);
+		if (ret < 0)
+			goto error_ret;
+
+		memcpy(&st->scan.chan[chan++], st->rx, 2);
+	}
+
+	iio_push_to_buffers_with_timestamp(indio_dev, &st->scan, pf->timestamp);
+
+error_ret:
+	gpiod_set_value(st->sample_gpio, 0);
+	mutex_unlock(&st->lock);
+	iio_trigger_notify_done(indio_dev->trig);
+
+	return IRQ_HANDLED;
+}
+
 static const struct iio_info ad2s1210_info = {
 	.read_raw = ad2s1210_read_raw,
 	.read_avail = ad2s1210_read_avail,
@@ -850,6 +925,13 @@ static int ad2s1210_probe(struct spi_device *spi)
 	indio_dev->num_channels = ARRAY_SIZE(ad2s1210_channels);
 	indio_dev->name = spi_get_device_id(spi)->name;
 
+	ret = devm_iio_triggered_buffer_setup(&spi->dev, indio_dev,
+					      &iio_pollfunc_store_time,
+					      &ad2s1210_trigger_handler, NULL);
+	if (ret < 0)
+		return dev_err_probe(&spi->dev, ret,
+				     "iio triggered buffer setup failed\n");
+
 	return devm_iio_device_register(&spi->dev, indio_dev);
 }
 
-- 
2.34.1