iio: accel: bma400: add support for bma400 spi

Add basic support for the Bosch Sensortec BMA400 3-axes ultra-low power
accelerometer when configured to use SPI.

Signed-off-by: Dan Robertson <dan@dlrobertson.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

diff --git a/drivers/iio/accel/Kconfig b/drivers/iio/accel/Kconfig
index 1080637..2e0c62c 100644 (file)
--- a/drivers/iio/accel/Kconfig
+++ b/drivers/iio/accel/Kconfig
@@ -116,18 +116,24 @@ config BMA400
        tristate "Bosch BMA400 3-Axis Accelerometer Driver"
        select REGMAP
        select BMA400_I2C if I2C
+       select BMA400_SPI if SPI
        help
          Say Y here if you want to build a driver for the Bosch BMA400
          triaxial acceleration sensor.
 
          To compile this driver as a module, choose M here: the
          module will be called bma400_core and you will also get
-         bma400_i2c if I2C is enabled.
+         bma400_i2c if I2C is enabled and bma400_spi if SPI is
+         enabled.
 
 config BMA400_I2C
        tristate
        depends on BMA400
 
+config BMA400_SPI
+       tristate
+       depends on BMA400
+
 config BMC150_ACCEL
        tristate "Bosch BMC150 Accelerometer Driver"
        select IIO_BUFFER

diff --git a/drivers/iio/accel/Makefile b/drivers/iio/accel/Makefile
index 3a051cf..4f6c1eb 100644 (file)
--- a/drivers/iio/accel/Makefile
+++ b/drivers/iio/accel/Makefile
@@ -16,6 +16,7 @@ obj-$(CONFIG_BMA180) += bma180.o
 obj-$(CONFIG_BMA220) += bma220_spi.o
 obj-$(CONFIG_BMA400) += bma400_core.o
 obj-$(CONFIG_BMA400_I2C) += bma400_i2c.o
+obj-$(CONFIG_BMA400_SPI) += bma400_spi.o
 obj-$(CONFIG_BMC150_ACCEL) += bmc150-accel-core.o
 obj-$(CONFIG_BMC150_ACCEL_I2C) += bmc150-accel-i2c.o
 obj-$(CONFIG_BMC150_ACCEL_SPI) += bmc150-accel-spi.o

diff --git a/drivers/iio/accel/bma400_spi.c b/drivers/iio/accel/bma400_spi.c
new file mode 100644 (file)
index 0000000..7c28259
--- /dev/null
+++ b/drivers/iio/accel/bma400_spi.c
@@ -0,0 +1,120 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * SPI IIO driver for Bosch BMA400 triaxial acceleration sensor.
+ *
+ * Copyright 2020 Dan Robertson <dan@dlrobertson.com>
+ *
+ */
+#include <linux/bits.h>
+#include <linux/init.h>
+#include <linux/mod_devicetable.h>
+#include <linux/module.h>
+#include <linux/regmap.h>
+#include <linux/spi/spi.h>
+
+#include "bma400.h"
+
+#define BMA400_MAX_SPI_READ 2
+#define BMA400_SPI_READ_BUFFER_SIZE (BMA400_MAX_SPI_READ + 1)
+
+static int bma400_regmap_spi_read(void *context,
+                                 const void *reg, size_t reg_size,
+                                 void *val, size_t val_size)
+{
+       struct device *dev = context;
+       struct spi_device *spi = to_spi_device(dev);
+       u8 result[BMA400_SPI_READ_BUFFER_SIZE];
+       ssize_t status;
+
+       if (val_size > BMA400_MAX_SPI_READ)
+               return -EINVAL;
+
+       status = spi_write_then_read(spi, reg, 1, result, val_size + 1);
+       if (status)
+               return status;
+
+       /*
+        * From the BMA400 datasheet:
+        *
+        * > For a basic read operation two bytes have to be read and the first
+        * > has to be dropped and the second byte must be interpreted.
+        */
+       memcpy(val, result + 1, val_size);
+
+       return 0;
+}
+
+static int bma400_regmap_spi_write(void *context, const void *data,
+                                  size_t count)
+{
+       struct device *dev = context;
+       struct spi_device *spi = to_spi_device(dev);
+
+       return spi_write(spi, data, count);
+}
+
+static struct regmap_bus bma400_regmap_bus = {
+       .read = bma400_regmap_spi_read,
+       .write = bma400_regmap_spi_write,
+       .read_flag_mask = BIT(7),
+       .max_raw_read = BMA400_MAX_SPI_READ,
+};
+
+static int bma400_spi_probe(struct spi_device *spi)
+{
+       const struct spi_device_id *id = spi_get_device_id(spi);
+       struct regmap *regmap;
+       unsigned int val;
+       int ret;
+
+       regmap = devm_regmap_init(&spi->dev, &bma400_regmap_bus,
+                                 &spi->dev, &bma400_regmap_config);
+       if (IS_ERR(regmap)) {
+               dev_err(&spi->dev, "failed to create regmap\n");
+               return PTR_ERR(regmap);
+       }
+
+       /*
+        * Per the bma400 datasheet, the first SPI read may
+        * return garbage. As the datasheet recommends, the
+        * chip ID register will be read here and checked
+        * again in the following probe.
+        */
+       ret = regmap_read(regmap, BMA400_CHIP_ID_REG, &val);
+       if (ret)
+               dev_err(&spi->dev, "Failed to read chip id register\n");
+
+       return bma400_probe(&spi->dev, regmap, id->name);
+}
+
+static int bma400_spi_remove(struct spi_device *spi)
+{
+       return bma400_remove(&spi->dev);
+}
+
+static const struct spi_device_id bma400_spi_ids[] = {
+       { "bma400", 0 },
+       { }
+};
+MODULE_DEVICE_TABLE(spi, bma400_spi_ids);
+
+static const struct of_device_id bma400_of_spi_match[] = {
+       { .compatible = "bosch,bma400" },
+       { }
+};
+MODULE_DEVICE_TABLE(of, bma400_of_spi_match);
+
+static struct spi_driver bma400_spi_driver = {
+       .driver = {
+               .name = "bma400",
+               .of_match_table = bma400_of_spi_match,
+       },
+       .probe    = bma400_spi_probe,
+       .remove   = bma400_spi_remove,
+       .id_table = bma400_spi_ids,
+};
+
+module_spi_driver(bma400_spi_driver);
+MODULE_AUTHOR("Dan Robertson <dan@dlrobertson.com>");
+MODULE_DESCRIPTION("Bosch BMA400 triaxial acceleration sensor (SPI)");
+MODULE_LICENSE("GPL");