iio: accel: add ADXL367 driver

The ADXL367 is an ultralow power, 3-axis MEMS accelerometer.

The ADXL367 does not alias input signals to achieve ultralow power
consumption, it samples the full bandwidth of the sensor at all
data rates. Measurement ranges of +-2g, +-4g, and +-8g are available,
with a resolution of 0.25mg/LSB on the +-2 g range.

In addition to its ultralow power consumption, the ADXL367
has many features to enable true system level power reduction.
It includes a deep multimode output FIFO, a built-in micropower
temperature sensor, and an internal ADC for synchronous conversion
of an additional analog input.

Signed-off-by: Cosmin Tanislav <cosmin.tanislav@analog.com>
Link: https://lore.kernel.org/r/20220214073810.781016-6-cosmin.tanislav@analog.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

1 files changed, 164 insertions, 0 deletions

diff --git a/drivers/iio/accel/adxl367_spi.c b/drivers/iio/accel/adxl367_spi.c
new file mode 100644
index 000000000000..26dfc821ebbe
--- /dev/null
+++ b/drivers/iio/accel/adxl367_spi.c
@@ -0,0 +1,164 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright (C) 2021 Analog Devices, Inc.
+ * Author: Cosmin Tanislav <cosmin.tanislav@analog.com>
+ */
+
+#include <linux/mod_devicetable.h>
+#include <linux/module.h>
+#include <linux/regmap.h>
+#include <linux/spi/spi.h>
+
+#include "adxl367.h"
+
+#define ADXL367_SPI_WRITE_COMMAND	0x0A
+#define ADXL367_SPI_READ_COMMAND	0x0B
+#define ADXL367_SPI_FIFO_COMMAND	0x0D
+
+struct adxl367_spi_state {
+	struct spi_device	*spi;
+
+	struct spi_message	reg_write_msg;
+	struct spi_transfer	reg_write_xfer[2];
+
+	struct spi_message	reg_read_msg;
+	struct spi_transfer	reg_read_xfer[2];
+
+	struct spi_message	fifo_msg;
+	struct spi_transfer	fifo_xfer[2];
+
+	/*
+	 * DMA (thus cache coherency maintenance) requires the
+	 * transfer buffers to live in their own cache lines.
+	 */
+	u8			reg_write_tx_buf[1] ____cacheline_aligned;
+	u8			reg_read_tx_buf[2];
+	u8			fifo_tx_buf[1];
+};
+
+static int adxl367_read_fifo(void *context, __be16 *fifo_buf,
+			     unsigned int fifo_entries)
+{
+	struct adxl367_spi_state *st = context;
+
+	st->fifo_xfer[1].rx_buf = fifo_buf;
+	st->fifo_xfer[1].len = fifo_entries * sizeof(*fifo_buf);
+
+	return spi_sync(st->spi, &st->fifo_msg);
+}
+
+static int adxl367_read(void *context, const void *reg_buf, size_t reg_size,
+			void *val_buf, size_t val_size)
+{
+	struct adxl367_spi_state *st = context;
+	u8 reg = ((const u8 *)reg_buf)[0];
+
+	st->reg_read_tx_buf[1] = reg;
+	st->reg_read_xfer[1].rx_buf = val_buf;
+	st->reg_read_xfer[1].len = val_size;
+
+	return spi_sync(st->spi, &st->reg_read_msg);
+}
+
+static int adxl367_write(void *context, const void *val_buf, size_t val_size)
+{
+	struct adxl367_spi_state *st = context;
+
+	st->reg_write_xfer[1].tx_buf = val_buf;
+	st->reg_write_xfer[1].len = val_size;
+
+	return spi_sync(st->spi, &st->reg_write_msg);
+}
+
+static struct regmap_bus adxl367_spi_regmap_bus = {
+	.read = adxl367_read,
+	.write = adxl367_write,
+};
+
+static const struct regmap_config adxl367_spi_regmap_config = {
+	.reg_bits = 8,
+	.val_bits = 8,
+};
+
+static const struct adxl367_ops adxl367_spi_ops = {
+	.read_fifo = adxl367_read_fifo,
+};
+
+static int adxl367_spi_probe(struct spi_device *spi)
+{
+	struct adxl367_spi_state *st;
+	struct regmap *regmap;
+
+	st = devm_kzalloc(&spi->dev, sizeof(*st), GFP_KERNEL);
+	if (!st)
+		return -ENOMEM;
+
+	st->spi = spi;
+
+	/*
+	 * Xfer:   [XFR1] [           XFR2           ]
+	 * Master:  0x0A   ADDR DATA0 DATA1 ... DATAN
+	 * Slave:   ....   ..........................
+	 */
+	st->reg_write_tx_buf[0] = ADXL367_SPI_WRITE_COMMAND;
+	st->reg_write_xfer[0].tx_buf = st->reg_write_tx_buf;
+	st->reg_write_xfer[0].len = sizeof(st->reg_write_tx_buf);
+	spi_message_init_with_transfers(&st->reg_write_msg,
+					st->reg_write_xfer, 2);
+
+	/*
+	 * Xfer:   [   XFR1  ] [         XFR2        ]
+	 * Master:  0x0B ADDR   .....................
+	 * Slave:   .........   DATA0 DATA1 ... DATAN
+	 */
+	st->reg_read_tx_buf[0] = ADXL367_SPI_READ_COMMAND;
+	st->reg_read_xfer[0].tx_buf = st->reg_read_tx_buf;
+	st->reg_read_xfer[0].len = sizeof(st->reg_read_tx_buf);
+	spi_message_init_with_transfers(&st->reg_read_msg,
+					st->reg_read_xfer, 2);
+
+	/*
+	 * Xfer:   [XFR1] [         XFR2        ]
+	 * Master:  0x0D   .....................
+	 * Slave:   ....   DATA0 DATA1 ... DATAN
+	 */
+	st->fifo_tx_buf[0] = ADXL367_SPI_FIFO_COMMAND;
+	st->fifo_xfer[0].tx_buf = st->fifo_tx_buf;
+	st->fifo_xfer[0].len = sizeof(st->fifo_tx_buf);
+	spi_message_init_with_transfers(&st->fifo_msg, st->fifo_xfer, 2);
+
+	regmap = devm_regmap_init(&spi->dev, &adxl367_spi_regmap_bus, st,
+				  &adxl367_spi_regmap_config);
+	if (IS_ERR(regmap))
+		return PTR_ERR(regmap);
+
+	return adxl367_probe(&spi->dev, &adxl367_spi_ops, st, regmap, spi->irq);
+}
+
+static const struct spi_device_id adxl367_spi_id[] = {
+	{ "adxl367", 0 },
+	{ },
+};
+MODULE_DEVICE_TABLE(spi, adxl367_spi_id);
+
+static const struct of_device_id adxl367_of_match[] = {
+	{ .compatible = "adi,adxl367" },
+	{ },
+};
+MODULE_DEVICE_TABLE(of, adxl367_of_match);
+
+static struct spi_driver adxl367_spi_driver = {
+	.driver = {
+		.name = "adxl367_spi",
+		.of_match_table = adxl367_of_match,
+	},
+	.probe = adxl367_spi_probe,
+	.id_table = adxl367_spi_id,
+};
+
+module_spi_driver(adxl367_spi_driver);
+
+MODULE_IMPORT_NS(IIO_ADXL367);
+MODULE_AUTHOR("Cosmin Tanislav <cosmin.tanislav@analog.com>");
+MODULE_DESCRIPTION("Analog Devices ADXL367 3-axis accelerometer SPI driver");
+MODULE_LICENSE("GPL");