Message-Id: <20210412075056.56301-3-tomas.melin@vaisala.com>
Date:   Mon, 12 Apr 2021 10:50:56 +0300
From:   Tomas Melin <tomas.melin@...sala.com>
To:     jic23@...nel.org, devicetree@...r.kernel.org
Cc:     linux-iio@...r.kernel.org, linux-kernel@...r.kernel.org,
        Tomas Melin <tomas.melin@...sala.com>
Subject: [PATCH 2/2] iio: accel: Add driver for Murata SCA3300 accelerometer

Add initial support for Murata SCA3300 3-axis industrial
accelerometer with digital SPI interface. This device also
provides a temperature measurement.

Device product page including datasheet can be found at:
https://www.murata.com/en-global/products/sensor/accel/sca3300

Signed-off-by: Tomas Melin <tomas.melin@...sala.com>
---
 drivers/iio/accel/Kconfig   |  13 ++
 drivers/iio/accel/Makefile  |   1 +
 drivers/iio/accel/sca3300.c | 434 ++++++++++++++++++++++++++++++++++++
 3 files changed, 448 insertions(+)
 create mode 100644 drivers/iio/accel/sca3300.c

diff --git a/drivers/iio/accel/Kconfig b/drivers/iio/accel/Kconfig
index cceda3cecbcf..0dbf7b648e8a 100644
--- a/drivers/iio/accel/Kconfig
+++ b/drivers/iio/accel/Kconfig
@@ -450,6 +450,19 @@ config SCA3000
 	  To compile this driver as a module, say M here: the module will be
 	  called sca3000.
 
+config SCA3300
+	tristate "Murata SCA3300 3-Axis Accelerometer Driver"
+	depends on SPI
+	select CRC8
+	select IIO_BUFFER
+	select IIO_TRIGGERED_BUFFER
+	help
+	  Say yes here to build support for Murata SCA3300 3-Axis
+	  accelerometer.
+
+	  To compile this driver as a module, choose M here: the module will be
+	  called sca3300.
+
 config STK8312
 	tristate "Sensortek STK8312 3-Axis Accelerometer Driver"
 	depends on I2C
diff --git a/drivers/iio/accel/Makefile b/drivers/iio/accel/Makefile
index 32cd1342a31a..4b56527a2b97 100644
--- a/drivers/iio/accel/Makefile
+++ b/drivers/iio/accel/Makefile
@@ -50,6 +50,7 @@ obj-$(CONFIG_MXC4005)		+= mxc4005.o
 obj-$(CONFIG_MXC6255)		+= mxc6255.o
 
 obj-$(CONFIG_SCA3000)		+= sca3000.o
+obj-$(CONFIG_SCA3300)		+= sca3300.o
 
 obj-$(CONFIG_STK8312)		+= stk8312.o
 obj-$(CONFIG_STK8BA50)		+= stk8ba50.o
diff --git a/drivers/iio/accel/sca3300.c b/drivers/iio/accel/sca3300.c
new file mode 100644
index 000000000000..112fb88ecd3a
--- /dev/null
+++ b/drivers/iio/accel/sca3300.c
@@ -0,0 +1,434 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (c) Vaisala Oyj. All rights reserved.
+ */
+#include <linux/crc8.h>
+#include <linux/delay.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>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/spi/spi.h>
+
+#define SCA3300_ALIAS "sca3300"
+
+#define SCA3300_REG_STATUS 0x6
+#define SCA3300_REG_MODE 0xd
+#define SCA3300_REG_WHOAMI 0x10
+#define SCA3300_VALUE_SW_RESET 0x20
+#define SCA3300_CRC8_POLYNOMIAL 0x1d
+#define SCA3300_X_READ 0
+#define SCA3300_X_WRITE BIT(7)
+#define SCA3300_DEVICE_ID 0x51
+#define SCA3300_RS_ERROR 0x3
+
+enum sca3300_scan_indexes {
+	SCA3300_ACC_X = 0,
+	SCA3300_ACC_Y,
+	SCA3300_ACC_Z,
+	SCA3300_TEMP,
+	SCA3300_TIMESTAMP,
+};
+
+#define SCA3300_ACCEL_CHANNEL(index, reg, axis) {			\
+		.type = IIO_ACCEL,					\
+		.address = reg,						\
+		.modified = 1,						\
+		.channel2 = IIO_MOD_##axis,				\
+		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |		\
+				      BIT(IIO_CHAN_INFO_PROCESSED),	\
+		.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),	\
+		.scan_index = index,					\
+		.scan_type = {						\
+			.sign = 's',					\
+			.realbits = 16,					\
+			.storagebits = 16,				\
+			.shift = 0,					\
+			.endianness = IIO_CPU,				\
+		},							\
+	}
+
+static const struct iio_chan_spec sca3300_channels[] = {
+	SCA3300_ACCEL_CHANNEL(SCA3300_ACC_X, 0x1, X),
+	SCA3300_ACCEL_CHANNEL(SCA3300_ACC_Y, 0x2, Y),
+	SCA3300_ACCEL_CHANNEL(SCA3300_ACC_Z, 0x3, Z),
+	{
+		.type = IIO_TEMP,
+		.address = 0x5,
+		.scan_index = SCA3300_TEMP,
+		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
+		.scan_type = {
+			.sign = 's',
+			.realbits = 16,
+			.storagebits = 16,
+			.shift = 0,
+			.endianness = IIO_CPU,
+		},
+	},
+	IIO_CHAN_SOFT_TIMESTAMP(4),
+};
+
+static const int sca3300_accel_scale[] = {2700, 1350, 5400, 5400};
+
+static const unsigned long sca3300_scan_masks[] = {
+	BIT(SCA3300_ACC_X) | BIT(SCA3300_ACC_Y) | BIT(SCA3300_ACC_Z) |
+	BIT(SCA3300_TEMP),
+	0};
+
+/**
+ * SCA3300 device data
+ *
+ * @spi SPI device structure
+ * @opmode Device operation mode
+ * @lock Data buffer lock
+ * @txbuf Transmit buffer
+ * @rxbuf Receive buffer
+ * @scan Triggered buffer. Four channel 16-bit data + 64-bit timestamp
+ */
+struct sca3300_data {
+	struct spi_device *spi;
+	u32 opmode;
+	struct mutex lock;
+	u8 txbuf[4];
+	u8 rxbuf[4];
+	struct {
+		s16 channels[4];
+		s64 ts __aligned(sizeof(s64));
+	} scan;
+};
+
+DECLARE_CRC8_TABLE(sca3300_crc_table);
+
+static int sca3300_transfer(struct sca3300_data *sca_data, int *val)
+{
+	struct spi_delay delay = {.value = 10, .unit = SPI_DELAY_UNIT_USECS};
+	int32_t ret;
+	int rs;
+	u8 crc;
+	struct spi_transfer xfers[2] = {
+		{
+			.tx_buf = sca_data->txbuf,
+			.rx_buf = NULL,
+			.len = ARRAY_SIZE(sca_data->txbuf),
+			.delay = delay,
+			.cs_change = 1,
+		},
+		{
+			.tx_buf = NULL,
+			.rx_buf = sca_data->rxbuf,
+			.len = ARRAY_SIZE(sca_data->rxbuf),
+			.delay = delay,
+			.cs_change = 0,
+		}
+	};
+
+	/* inverted crc value as described in device data sheet */
+	crc = ~crc8(sca3300_crc_table, &sca_data->txbuf[0], 3, CRC8_INIT_VALUE);
+	sca_data->txbuf[3] = crc;
+
+	ret = spi_sync_transfer(sca_data->spi, xfers, 2);
+	if (ret < 0) {
+		dev_err(&sca_data->spi->dev,
+			"transfer error, error: %d\n", ret);
+		return -EIO;
+	}
+
+	crc = ~crc8(sca3300_crc_table, &sca_data->rxbuf[0], 3, CRC8_INIT_VALUE);
+	if (sca_data->rxbuf[3] != crc) {
+		dev_err(&sca_data->spi->dev, "CRC checksum mismatch");
+		return -EIO;
+	}
+
+	/* get return status */
+	rs = sca_data->rxbuf[0] & 0x03;
+	if (rs == SCA3300_RS_ERROR)
+		return rs;
+
+	*val = (s16)(sca_data->rxbuf[2] | (sca_data->rxbuf[1] << 8));
+
+	return 0;
+}
+
+static int sca3300_read_reg(struct sca3300_data *sca_data, u8 reg, int *val)
+{
+	int ret;
+
+	mutex_lock(&sca_data->lock);
+	sca_data->txbuf[0] = SCA3300_X_READ | (reg << 2);
+	ret = sca3300_transfer(sca_data, val);
+	if (ret > 0) {
+		sca_data->txbuf[0] = SCA3300_X_READ | (SCA3300_REG_STATUS << 2);
+		ret = sca3300_transfer(sca_data, val);
+		/* status 0 = startup, 0x2 = mode change */
+		if (ret > 0 && *val != 0 && *val != 0x2) {
+			dev_err_ratelimited(&sca_data->spi->dev,
+					    "device status: %x\n",
+					    (u16)*val);
+			mutex_unlock(&sca_data->lock);
+			return -EIO;
+		}
+		if (ret > 0)
+			ret = 0;
+	}
+	mutex_unlock(&sca_data->lock);
+
+	return ret;
+}
+
+static int sca3300_write_reg(struct sca3300_data *sca_data, u8 reg, int val)
+{
+	int reg_val = 0;
+	int ret;
+
+	mutex_lock(&sca_data->lock);
+	sca_data->txbuf[0] = SCA3300_X_WRITE | (reg << 2);
+	sca_data->txbuf[1] = val >> 8;
+	sca_data->txbuf[2] = val & 0xFF;
+	ret = sca3300_transfer(sca_data, &reg_val);
+	if (ret > 0) {
+		sca_data->txbuf[0] = SCA3300_X_READ | (SCA3300_REG_STATUS << 2);
+		ret = sca3300_transfer(sca_data, &reg_val);
+		/* status 0 = startup, 0x2 = mode change */
+		if (ret > 0 && reg_val != 0 && reg_val != 0x2) {
+			dev_err_ratelimited(&sca_data->spi->dev,
+					    "device status: %x\n",
+					    (u16)reg_val);
+			mutex_unlock(&sca_data->lock);
+			return -EIO;
+		}
+		if (ret > 0)
+			ret = 0;
+	}
+	mutex_unlock(&sca_data->lock);
+
+	return ret;
+}
+
+static int sca3300_write_raw(struct iio_dev *indio_dev,
+			     struct iio_chan_spec const *chan,
+			     int val, int val2, long mask)
+{
+	struct sca3300_data *data = iio_priv(indio_dev);
+
+	switch (mask) {
+	case IIO_CHAN_INFO_SCALE:
+		if (val < 0 || val > 3)
+			return -EINVAL;
+		return sca3300_write_reg(data, SCA3300_REG_MODE, val);
+	default:
+		return -EINVAL;
+	}
+}
+
+static int sca3300_read_raw(struct iio_dev *indio_dev,
+			    struct iio_chan_spec const *chan,
+			    int *val, int *val2, long mask)
+{
+	struct sca3300_data *data = iio_priv(indio_dev);
+	int ret;
+	int reg_val;
+
+	switch (mask) {
+	case IIO_CHAN_INFO_RAW:
+		ret = sca3300_read_reg(data, chan->address, val);
+		if (ret < 0)
+			return ret;
+		return IIO_VAL_INT;
+	case IIO_CHAN_INFO_SCALE:
+		ret = sca3300_read_reg(data, SCA3300_REG_MODE, &reg_val);
+		if (ret < 0)
+			return ret;
+		*val = sca3300_accel_scale[reg_val];
+		return IIO_VAL_INT;
+	case IIO_CHAN_INFO_PROCESSED:
+		ret = sca3300_read_reg(data, SCA3300_REG_MODE, &reg_val);
+		if (ret < 0)
+			return ret;
+		*val2 = sca3300_accel_scale[reg_val];
+		ret = sca3300_read_reg(data, chan->address, val);
+		if (ret < 0)
+			return ret;
+		return IIO_VAL_FRACTIONAL;
+	default:
+		return -EINVAL;
+	}
+}
+
+static irqreturn_t sca3300_trigger_handler(int irq, void *p)
+{
+	struct iio_poll_func *pf = p;
+	struct iio_dev *indio_dev = pf->indio_dev;
+	struct sca3300_data *data = iio_priv(indio_dev);
+	s64 time_ns = iio_get_time_ns(indio_dev);
+	int bit, ret, val, i = 0;
+
+	for_each_set_bit(bit, indio_dev->active_scan_mask,
+			 indio_dev->masklength) {
+		ret = sca3300_read_reg(data, sca3300_channels[bit].address,
+				       &val);
+		if (ret < 0)
+			goto out;
+		if (ARRAY_SIZE(data->scan.channels) > i)
+			((s16 *)data->scan.channels)[i++] = val;
+	}
+
+	iio_push_to_buffers_with_timestamp(indio_dev, &data->scan, time_ns);
+out:
+	iio_trigger_notify_done(indio_dev->trig);
+
+	return IRQ_HANDLED;
+}
+
+static int sca3300_init(struct sca3300_data *sca_data,
+			struct iio_dev *indio_dev)
+{
+	int ret;
+	int value = 0;
+
+	if (sca_data->opmode < 1 || sca_data->opmode > 4)
+		return -EINVAL;
+
+	ret = sca3300_write_reg(sca_data, SCA3300_REG_MODE,
+				SCA3300_VALUE_SW_RESET);
+	if (ret != 0)
+		return ret;
+	usleep_range(2e3, 10e3);
+
+	ret = sca3300_write_reg(sca_data, SCA3300_REG_MODE,
+				sca_data->opmode - 1);
+	if (ret != 0)
+		return ret;
+	msleep(100);
+	ret = sca3300_read_reg(sca_data, SCA3300_REG_WHOAMI, &value);
+	if (ret != 0)
+		return ret;
+
+	if (value != SCA3300_DEVICE_ID) {
+		dev_err(&sca_data->spi->dev, "device id not expected value\n");
+		return -EIO;
+	}
+	return 0;
+}
+
+static int sca3300_debugfs_reg_access(struct iio_dev *indio_dev,
+				      unsigned int reg, unsigned int writeval,
+				      unsigned int *readval)
+{
+	struct sca3300_data *data = iio_priv(indio_dev);
+	int value;
+	int ret;
+
+	if (reg > 0x1f)
+		return -EINVAL;
+
+	if (!readval)
+		return sca3300_write_reg(data, reg, writeval);
+
+	ret = sca3300_read_reg(data, reg, &value);
+	if (ret < 0)
+		return ret;
+
+	*readval = (unsigned int)value;
+
+	return 0;
+}
+
+static const struct iio_info sca3300_info = {
+	.read_raw = sca3300_read_raw,
+	.write_raw = sca3300_write_raw,
+	.debugfs_reg_access = &sca3300_debugfs_reg_access,
+};
+
+static int sca3300_probe(struct spi_device *spi)
+{
+	struct sca3300_data *sca_data;
+	struct iio_dev *indio_dev;
+	int ret;
+
+	indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*sca_data));
+	if (!indio_dev) {
+		dev_err(&spi->dev,
+			"failed to allocate memory for iio device\n");
+		return -ENOMEM;
+	}
+
+	sca_data = iio_priv(indio_dev);
+	mutex_init(&sca_data->lock);
+	sca_data->spi = spi;
+	spi_set_drvdata(spi, indio_dev);
+
+	crc8_populate_msb(sca3300_crc_table, SCA3300_CRC8_POLYNOMIAL);
+
+	indio_dev->dev.parent = &spi->dev;
+	indio_dev->info = &sca3300_info;
+	indio_dev->name = SCA3300_ALIAS;
+	indio_dev->modes = INDIO_DIRECT_MODE | INDIO_BUFFER_TRIGGERED;
+	indio_dev->channels = sca3300_channels;
+	indio_dev->num_channels = ARRAY_SIZE(sca3300_channels);
+	indio_dev->available_scan_masks = sca3300_scan_masks;
+
+	if (spi->dev.of_node) {
+		ret = of_property_read_u32(spi->dev.of_node, "murata,opmode",
+					   &sca_data->opmode);
+		if (ret < 0)
+			return ret;
+	}
+
+	ret = sca3300_init(sca_data, indio_dev);
+	if (ret < 0) {
+		dev_err(&spi->dev, "failed to init device, error: %d\n", ret);
+		return ret;
+	}
+
+	ret = iio_triggered_buffer_setup(indio_dev, iio_pollfunc_store_time,
+					 sca3300_trigger_handler, NULL);
+	if (ret < 0) {
+		dev_err(&spi->dev,
+			"iio triggered buffer setup failed, error: %d\n", ret);
+		return ret;
+	}
+
+	ret = devm_iio_device_register(&spi->dev, indio_dev);
+	if (ret < 0) {
+		dev_err(&spi->dev, "iio device register failed, error: %d\n",
+			ret);
+		iio_triggered_buffer_cleanup(indio_dev);
+		return ret;
+	}
+
+	return 0;
+}
+
+static int sca3300_remove(struct spi_device *spi)
+{
+	struct iio_dev *indio_dev = spi_get_drvdata(spi);
+
+	iio_triggered_buffer_cleanup(indio_dev);
+	return 0;
+}
+
+static const struct of_device_id sca3300_dt_ids[] = {
+	{ .compatible = "murata,sca3300"},
+	{},
+};
+MODULE_DEVICE_TABLE(of, sca3300_dt_ids);
+
+static struct spi_driver sca3300_driver = {
+	.driver = {
+		.name		= SCA3300_ALIAS,
+		.owner		= THIS_MODULE,
+		.of_match_table = of_match_ptr(sca3300_dt_ids),
+	},
+
+	.probe	= sca3300_probe,
+	.remove	= sca3300_remove,
+};
+
+module_spi_driver(sca3300_driver);
+
+MODULE_AUTHOR("Tomas Melin <tomas.melin@...sala.com>");
+MODULE_DESCRIPTION("Murata SCA3300 SPI Accelerometer");
+MODULE_LICENSE("GPL v2");
-- 
2.21.3

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