iio: pressure: bmp280: add SPI interface driver

This patch mimics the SPI functionality found in the misc driver in
drivers/misc/bh085-spi.c to make it possible to reuse the existing
BMP280/BMP180/BMP085 driver with all clients of the other driver.
The adoption is straight-forward since like the other driver, it is
a simple matter of using regmap.

This driver is also so obviously inspired/copied from the old misc
driver in drivers/misc/bmp085.c that I just took the liberty to
add in the authors of the other drivers + self in the core driver
file.

The MISC driver also supports a variant named "BMP181" so include
that here to be complete in comparison to the old driver.

The bus mapping code for SPI was written by Akinobu Mita.

Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
Tested-by: Akinobu Mita <akinobu.mita@gmail.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

4 files changed, 140 insertions, 3 deletions

diff --git a/drivers/iio/pressure/Kconfig b/drivers/iio/pressure/Kconfig
index 3d0d311acb1d..d130cdc78f43 100644
--- a/drivers/iio/pressure/Kconfig
+++ b/drivers/iio/pressure/Kconfig
@@ -7,17 +7,20 @@ menu "Pressure sensors"
 
 config BMP280
         tristate "Bosch Sensortec BMP180/BMP280 pressure sensor I2C driver"
-        depends on I2C
+        depends on (I2C || SPI_MASTER)
         depends on !(BMP085_I2C=y || BMP085_I2C=m)
+        depends on !(BMP085_SPI=y || BMP085_SPI=m)
         select REGMAP
         select BMP280_I2C if (I2C)
+        select BMP280_SPI if (SPI_MASTER)
         help
           Say yes here to build support for Bosch Sensortec BMP180 and BMP280
           pressure and temperature sensors. Also supports the BE280 with
           an additional humidity sensor channel.
 
-          To compile this driver as a module, choose M here: the modules
-          will be called bmp280-i2c and bmp280.
+          To compile this driver as a module, choose M here: the core module
+          will be called bmp280 and you will also get bmp280-i2c for I2C
+          and/or bmp280-spi for SPI support.
 
 config BMP280_I2C
         tristate
@@ -25,6 +28,12 @@ config BMP280_I2C
         depends on I2C
         select REGMAP_I2C
 
+config BMP280_SPI
+        tristate
+        depends on BMP280
+        depends on SPI_MASTER
+        select REGMAP
+
 config HID_SENSOR_PRESS
         depends on HID_SENSOR_HUB
         select IIO_BUFFER
diff --git a/drivers/iio/pressure/Makefile b/drivers/iio/pressure/Makefile
index 736f4305fe46..7f395bed5e88 100644
--- a/drivers/iio/pressure/Makefile
+++ b/drivers/iio/pressure/Makefile
@@ -6,6 +6,7 @@
 obj-$(CONFIG_BMP280) += bmp280.o
 bmp280-objs := bmp280-core.o bmp280-regmap.o
 obj-$(CONFIG_BMP280_I2C) += bmp280-i2c.o
+obj-$(CONFIG_BMP280_SPI) += bmp280-spi.o
 obj-$(CONFIG_HID_SENSOR_PRESS)   += hid-sensor-press.o
 obj-$(CONFIG_HP03) += hp03.o
 obj-$(CONFIG_MPL115) += mpl115.o
diff --git a/drivers/iio/pressure/bmp280-core.c b/drivers/iio/pressure/bmp280-core.c
index f1b5f8c0ac8c..43bd0b07619c 100644
--- a/drivers/iio/pressure/bmp280-core.c
+++ b/drivers/iio/pressure/bmp280-core.c
@@ -1,5 +1,9 @@
 /*
+ * Copyright (c) 2010 Christoph Mair <christoph.mair@gmail.com>
+ * Copyright (c) 2012 Bosch Sensortec GmbH
+ * Copyright (c) 2012 Unixphere AB
  * Copyright (c) 2014 Intel Corporation
+ * Copyright (c) 2016 Linus Walleij <linus.walleij@linaro.org>
  *
  * Driver for Bosch Sensortec BMP180 and BMP280 digital pressure sensor.
  *
diff --git a/drivers/iio/pressure/bmp280-spi.c b/drivers/iio/pressure/bmp280-spi.c
new file mode 100644
index 000000000000..216e64b682bf
--- /dev/null
+++ b/drivers/iio/pressure/bmp280-spi.c
@@ -0,0 +1,123 @@
+/*
+ * SPI interface for the BMP280 driver
+ *
+ * Inspired by the older BMP085 driver drivers/misc/bmp085-spi.c
+ */
+#include <linux/module.h>
+#include <linux/spi/spi.h>
+#include <linux/err.h>
+#include <linux/regmap.h>
+
+#include "bmp280.h"
+
+static int bmp280_regmap_spi_write(void *context, const void *data,
+                                   size_t count)
+{
+        struct device *dev = context;
+        struct spi_device *spi = to_spi_device(dev);
+        u8 buf[2];
+
+        memcpy(buf, data, 2);
+        /*
+         * The SPI register address (= full register address without bit 7) and
+         * the write command (bit7 = RW = '0')
+         */
+        buf[0] &= ~0x80;
+
+        return spi_write_then_read(spi, buf, 2, NULL, 0);
+}
+
+static int bmp280_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);
+
+        return spi_write_then_read(spi, reg, reg_size, val, val_size);
+}
+
+static struct regmap_bus bmp280_regmap_bus = {
+        .write = bmp280_regmap_spi_write,
+        .read = bmp280_regmap_spi_read,
+        .reg_format_endian_default = REGMAP_ENDIAN_BIG,
+        .val_format_endian_default = REGMAP_ENDIAN_BIG,
+};
+
+static int bmp280_spi_probe(struct spi_device *spi)
+{
+        const struct spi_device_id *id = spi_get_device_id(spi);
+        struct regmap *regmap;
+        const struct regmap_config *regmap_config;
+        int ret;
+
+        spi->bits_per_word = 8;
+        ret = spi_setup(spi);
+        if (ret < 0) {
+                dev_err(&spi->dev, "spi_setup failed!\n");
+                return ret;
+        }
+
+        switch (id->driver_data) {
+        case BMP180_CHIP_ID:
+                regmap_config = &bmp180_regmap_config;
+                break;
+        case BMP280_CHIP_ID:
+        case BME280_CHIP_ID:
+                regmap_config = &bmp280_regmap_config;
+                break;
+        default:
+                return -EINVAL;
+        }
+
+        regmap = devm_regmap_init(&spi->dev,
+                                  &bmp280_regmap_bus,
+                                  &spi->dev,
+                                  regmap_config);
+        if (IS_ERR(regmap)) {
+                dev_err(&spi->dev, "failed to allocate register map\n");
+                return PTR_ERR(regmap);
+        }
+
+        return bmp280_common_probe(&spi->dev,
+                                   regmap,
+                                   id->driver_data,
+                                   id->name);
+}
+
+static int bmp280_spi_remove(struct spi_device *spi)
+{
+        return bmp280_common_remove(&spi->dev);
+}
+
+static const struct of_device_id bmp280_of_spi_match[] = {
+        { .compatible = "bosch,bmp085", },
+        { .compatible = "bosch,bmp180", },
+        { .compatible = "bosch,bmp181", },
+        { .compatible = "bosch,bmp280", },
+        { .compatible = "bosch,bme280", },
+        { },
+};
+MODULE_DEVICE_TABLE(of, bmp280_of_spi_match);
+
+static const struct spi_device_id bmp280_spi_id[] = {
+        { "bmp180", BMP180_CHIP_ID },
+        { "bmp181", BMP180_CHIP_ID },
+        { "bmp280", BMP280_CHIP_ID },
+        { "bme280", BME280_CHIP_ID },
+        { }
+};
+MODULE_DEVICE_TABLE(spi, bmp280_spi_id);
+
+static struct spi_driver bmp280_spi_driver = {
+        .driver = {
+                .name = "bmp280",
+                .of_match_table = bmp280_of_spi_match,
+        },
+        .id_table = bmp280_spi_id,
+        .probe = bmp280_spi_probe,
+        .remove = bmp280_spi_remove,
+};
+module_spi_driver(bmp280_spi_driver);
+
+MODULE_DESCRIPTION("BMP280 SPI bus driver");
+MODULE_LICENSE("GPL");