WIP: iio: accel: Add driver for Qualcomm Sensor Manager accelerometers

Add a driver for accelerometers provided by the Qualcomm Sensor Manager service.

drivers/iio/accel/Kconfig

@@ -380,6 +380,16 @@ config IIO_CROS_EC_ACCEL_LEGACY
 	  Sensor data is retrieved through IO memory.
 	  Newer devices should use IIO_CROS_EC_SENSORS.
 
+config IIO_QCOM_SMGR_ACCEL
+	tristate "Qualcomm SSC Sensor Manager Accelerometer Sensor"
+	depends on IIO_QCOM_SMGR
+	select IIO_BUFFER
+	select IIO_KFIFO_BUF
+	help
+	  Say yes here to get support for accelerometers connected to
+	  a Qualcomm Snapdragon Sensor Core and accessed through its
+	  Sensor Manager service.
+
 config IIO_ST_ACCEL_3AXIS
 	tristate "STMicroelectronics accelerometers 3-Axis Driver"
 	depends on (I2C || SPI_MASTER) && SYSFS

drivers/iio/accel/Makefile

@@ -75,6 +75,8 @@ obj-$(CONFIG_STK8BA50)		+= stk8ba50.o
 
 obj-$(CONFIG_IIO_CROS_EC_ACCEL_LEGACY) += cros_ec_accel_legacy.o
 
+obj-$(CONFIG_IIO_QCOM_SMGR_ACCEL) += smgr_accel.o
+
 obj-$(CONFIG_IIO_SSP_SENSORS_COMMONS) += ssp_accel_sensor.o
 
 obj-$(CONFIG_IIO_ST_ACCEL_3AXIS) += st_accel.o

drivers/iio/accel/smgr_accel.c

@@ -0,0 +1,234 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/* 
+ * Qualcomm Sensor Manager accelerometer driver
+ * 
+ * Copyright (c) 2022, Yassine Oudjana <y.oudjana@protonmail.com>
+ */
+
+#include <linux/mod_devicetable.h>
+#include <linux/platform_device.h>
+#include <linux/iio/buffer.h>
+#include <linux/iio/common/qcom_smgr.h>
+#include <linux/iio/iio.h>
+#include <linux/iio/kfifo_buf.h>
+
+static int smgr_accel_read_raw(struct iio_dev *iio_dev,
+			       struct iio_chan_spec const *chan, int *val,
+			       int *val2, long mask)
+{
+	struct smgr_iio_priv *priv = iio_priv(iio_dev);
+
+	switch (mask) {
+	case IIO_CHAN_INFO_SAMP_FREQ:
+		*val = priv->sensor->data_types[0].cur_sample_rate;
+		return IIO_VAL_INT;
+	case IIO_CHAN_INFO_SCALE:
+		/*
+		 * TODO: Find out if the scale is standard across devices or
+		 * find a way to get the correct scale for a device
+		 *
+		 * Device reports around 640000 when axis is aligned with
+		 * gravity, therefore scale is 9.81m/s^2 / 640000.
+		 */
+		*val = 0;
+		*val2 = 15328; /* scale * 10^9 */
+		return IIO_VAL_INT_PLUS_NANO;
+	}
+
+	return -EINVAL;
+}
+
+static int smgr_accel_write_raw(struct iio_dev *iio_dev,
+				struct iio_chan_spec const *chan, int val,
+				int val2, long mask)
+{
+	struct smgr_iio_priv *priv = iio_priv(iio_dev);
+
+	switch (mask) {
+	case IIO_CHAN_INFO_SAMP_FREQ:
+		priv->sensor->data_types[0].cur_sample_rate = val;
+
+		/*
+		 * Send new SMGR buffering request with updated rates
+		 * if buffer is enabled
+		 */
+		if (iio_buffer_enabled(iio_dev))
+			return iio_dev->setup_ops->postenable(iio_dev);
+
+		return 0;
+	}
+
+	return -EINVAL;
+}
+
+static int smgr_accel_read_avail(struct iio_dev *iio_dev,
+				 struct iio_chan_spec const *chan,
+				 const int **vals, int *type, int *length,
+				 long mask)
+{
+	struct smgr_iio_priv *priv = iio_priv(iio_dev);
+	const int samp_freq_vals[3] = {
+		1, 1, priv->sensor->data_types[0].max_sample_rate
+	};
+
+	switch (mask) {
+	case IIO_CHAN_INFO_SAMP_FREQ:
+		*type = IIO_VAL_INT;
+		*vals = samp_freq_vals;
+		*length = ARRAY_SIZE(samp_freq_vals);
+		return IIO_AVAIL_RANGE;
+	}
+
+	return -EINVAL;
+}
+
+static const struct iio_info smgr_accel_iio_info = {
+	.read_raw = smgr_accel_read_raw,
+	.write_raw = smgr_accel_write_raw,
+	.read_avail = smgr_accel_read_avail,
+};
+
+/* TODO: Get mount matrix from SSC or read it from the device tree */
+static const struct iio_mount_matrix qcom_ssc_mount_matrix = {
+	.rotation = {
+		"0", "-1", "0",
+		"-1", "0", "0",
+		"0", "0", "1"
+	}
+};
+
+static const struct iio_mount_matrix *
+smgr_accel_get_mount_matrix(const struct iio_dev *iio_dev,
+			    const struct iio_chan_spec *chan)
+{
+	return &qcom_ssc_mount_matrix;
+}
+
+static const struct iio_chan_spec_ext_info smgr_accel_ext_info[] = {
+	IIO_MOUNT_MATRIX(IIO_SHARED_BY_DIR, smgr_accel_get_mount_matrix),
+	{}
+};
+
+static const struct iio_chan_spec smgr_accel_iio_channels[] = {
+	{
+		.type = IIO_ACCEL,
+		.modified = true,
+		.channel2 = IIO_MOD_X,
+		.scan_index = 0,
+		.scan_type = {
+			.sign = 's',
+			.realbits = 24,
+			.storagebits = 32,
+			.endianness = IIO_LE,
+		},
+		.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE) |
+					    BIT(IIO_CHAN_INFO_SAMP_FREQ),
+		.ext_info = smgr_accel_ext_info
+	},
+	{
+		.type = IIO_ACCEL,
+		.modified = true,
+		.channel2 = IIO_MOD_Y,
+		.scan_index = 1,
+		.scan_type = {
+			.sign = 's',
+			.realbits = 24,
+			.storagebits = 32,
+			.endianness = IIO_LE,
+		},
+		.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE) |
+					    BIT(IIO_CHAN_INFO_SAMP_FREQ),
+		.ext_info = smgr_accel_ext_info
+	},
+	{
+		.type = IIO_ACCEL,
+		.modified = true,
+		.channel2 = IIO_MOD_Z,
+		.scan_index = 2,
+		.scan_type = {
+			.sign = 's',
+			.realbits = 24,
+			.storagebits = 32,
+			.endianness = IIO_LE,
+		},
+		.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE) |
+					    BIT(IIO_CHAN_INFO_SAMP_FREQ),
+		.ext_info = smgr_accel_ext_info
+	},
+	{
+		.type = IIO_TIMESTAMP,
+		.channel = -1,
+		.scan_index = 3,
+		.scan_type = {
+			.sign = 'u',
+			.realbits = 32,
+			.storagebits = 64,
+			.endianness = IIO_LE,
+		},
+	},
+};
+
+static int smgr_accel_probe(struct platform_device *pdev)
+{
+	struct iio_dev *iio_dev;
+	struct smgr_iio_priv *priv;
+	int ret;
+
+	iio_dev = devm_iio_device_alloc(&pdev->dev, sizeof(*priv));
+	if (!iio_dev)
+		return -ENOMEM;
+
+	priv = iio_priv(iio_dev);
+	priv->sensor = *(struct smgr_sensor **)pdev->dev.platform_data;
+	priv->sensor->iio_dev = iio_dev;
+
+	iio_dev->name = "qcom-smgr-accel";
+	iio_dev->info = &smgr_accel_iio_info;
+	iio_dev->channels = smgr_accel_iio_channels;
+	iio_dev->num_channels = ARRAY_SIZE(smgr_accel_iio_channels);
+
+	ret = devm_iio_kfifo_buffer_setup(&pdev->dev, iio_dev,
+					  &smgr_buffer_ops);
+	if (ret) {
+		dev_err(&pdev->dev, "Failed to setup buffer: %pe\n",
+			ERR_PTR(ret));
+		return ret;
+	}
+
+	ret = devm_iio_device_register(&pdev->dev, iio_dev);
+	if (ret) {
+		dev_err(&pdev->dev, "Failed to register IIO device: %pe\n",
+			ERR_PTR(ret));
+		return ret;
+	}
+
+	return 0;
+}
+
+static void smgr_accel_remove(struct platform_device *pdev)
+{
+	struct iio_dev *iio_dev = platform_get_drvdata(pdev);
+	struct smgr_iio_priv *priv = iio_priv(iio_dev);
+
+	priv->sensor->iio_dev = NULL;
+}
+
+static const struct platform_device_id smgr_accel_ids[] = {
+	{ .name = "qcom-smgr-accel" },
+	{ /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(platform, smgr_accel_ids);
+
+static struct platform_driver smgr_accel_driver = {
+	.probe = smgr_accel_probe,
+	.remove = smgr_accel_remove,
+	.driver	= {
+		.name = "smgr_accel",
+	},
+	.id_table = smgr_accel_ids,
+};
+module_platform_driver(smgr_accel_driver);
+
+MODULE_AUTHOR("Yassine Oudjana <y.oudjana@protonmail.com>");
+MODULE_DESCRIPTION("Qualcomm Sensor Manager accelerometer driver");
+MODULE_LICENSE("GPL");