iio: accel: kxsd9: Split out SPI transport

This moves the KXSD9 SPI transport out to its own file and Kconfig
entry, so that we will be able to add another transport method.
We export the common probe and add a local header file for the
functionality shared between the main driver and the transport
driver.

We make the SPI transport the default for the driver if SPI is
available and the KXSD9 driver was selected, so the oldconfig
upgrade path will be clear.

Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Tested-by: Jonathan Cameron <jic23@kernel.org>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

5 files changed, 173 insertions, 127 deletions

diff --git a/drivers/iio/accel/Kconfig b/drivers/iio/accel/Kconfig
index 13b8a18..89bc5c5 100644
--- a/drivers/iio/accel/Kconfig
+++ b/drivers/iio/accel/Kconfig
@@ -119,7 +119,6 @@ config IIO_ST_ACCEL_SPI_3AXIS
 
 config KXSD9
 	tristate "Kionix KXSD9 Accelerometer Driver"
-	depends on SPI
 	help
 	  Say yes here to build support for the Kionix KXSD9 accelerometer.
 	  Currently this only supports the device via an SPI interface.
@@ -127,6 +126,15 @@ config KXSD9
 	  To compile this driver as a module, choose M here: the module
 	  will be called kxsd9.
 
+config KXSD9_SPI
+	tristate "Kionix KXSD9 SPI transport"
+	depends on KXSD9
+	depends on SPI
+	default KXSD9
+	help
+	  Say yes here to enable the Kionix KXSD9 accelerometer
+	  SPI transport channel.
+
 config KXCJK1013
 	tristate "Kionix 3-Axis Accelerometer Driver"
 	depends on I2C
diff --git a/drivers/iio/accel/Makefile b/drivers/iio/accel/Makefile
index e974841..2fe41d7 100644
--- a/drivers/iio/accel/Makefile
+++ b/drivers/iio/accel/Makefile
@@ -13,6 +13,7 @@ obj-$(CONFIG_DMARD09)	+= dmard09.o
 obj-$(CONFIG_HID_SENSOR_ACCEL_3D) += hid-sensor-accel-3d.o
 obj-$(CONFIG_KXCJK1013) += kxcjk-1013.o
 obj-$(CONFIG_KXSD9)	+= kxsd9.o
+obj-$(CONFIG_KXSD9_SPI)	+= kxsd9-spi.o
 
 obj-$(CONFIG_MMA7455)		+= mma7455_core.o
 obj-$(CONFIG_MMA7455_I2C)	+= mma7455_i2c.o
diff --git a/drivers/iio/accel/kxsd9-spi.c b/drivers/iio/accel/kxsd9-spi.c
new file mode 100644
index 0000000..ec9d00d
--- /dev/null
+++ b/drivers/iio/accel/kxsd9-spi.c
@@ -0,0 +1,110 @@
+#include <linux/device.h>
+#include <linux/kernel.h>
+#include <linux/spi/spi.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+
+#include "kxsd9.h"
+
+#define KXSD9_READ(a) (0x80 | (a))
+#define KXSD9_WRITE(a) (a)
+
+static int kxsd9_spi_readreg(struct kxsd9_transport *tr, u8 address)
+{
+	struct spi_device *spi = tr->trdev;
+
+	return spi_w8r8(spi, KXSD9_READ(address));
+}
+
+static int kxsd9_spi_writereg(struct kxsd9_transport *tr, u8 address, u8 val)
+{
+	struct spi_device *spi = tr->trdev;
+
+	tr->tx[0] = KXSD9_WRITE(address),
+	tr->tx[1] = val;
+	return spi_write(spi, tr->tx, 2);
+}
+
+static int kxsd9_spi_write2(struct kxsd9_transport *tr, u8 b1, u8 b2)
+{
+	struct spi_device *spi = tr->trdev;
+
+	tr->tx[0] = b1;
+	tr->tx[1] = b2;
+	return spi_write(spi, tr->tx, 2);
+}
+
+static int kxsd9_spi_readval(struct kxsd9_transport *tr, u8 address)
+{
+	struct spi_device *spi = tr->trdev;
+	struct spi_transfer xfers[] = {
+		{
+			.bits_per_word = 8,
+			.len = 1,
+			.delay_usecs = 200,
+			.tx_buf = tr->tx,
+		}, {
+			.bits_per_word = 8,
+			.len = 2,
+			.rx_buf = tr->rx,
+		},
+	};
+	int ret;
+
+	tr->tx[0] = KXSD9_READ(address);
+	ret = spi_sync_transfer(spi, xfers, ARRAY_SIZE(xfers));
+	if (!ret)
+		ret = (((u16)(tr->rx[0])) << 8) | (tr->rx[1]);
+	return ret;
+}
+
+static int kxsd9_spi_probe(struct spi_device *spi)
+{
+	struct kxsd9_transport *transport;
+	int ret;
+
+	transport = devm_kzalloc(&spi->dev, sizeof(*transport), GFP_KERNEL);
+	if (!transport)
+		return -ENOMEM;
+
+	transport->trdev = spi;
+	transport->readreg = kxsd9_spi_readreg;
+	transport->writereg = kxsd9_spi_writereg;
+	transport->write2 = kxsd9_spi_write2;
+	transport->readval = kxsd9_spi_readval;
+	spi->mode = SPI_MODE_0;
+	spi_setup(spi);
+
+	ret = kxsd9_common_probe(&spi->dev,
+				 transport,
+				 spi_get_device_id(spi)->name);
+	if (ret)
+		return ret;
+
+	return 0;
+}
+
+static int kxsd9_spi_remove(struct spi_device *spi)
+{
+	return kxsd9_common_remove(&spi->dev);
+}
+
+static const struct spi_device_id kxsd9_spi_id[] = {
+	{"kxsd9", 0},
+	{ },
+};
+MODULE_DEVICE_TABLE(spi, kxsd9_spi_id);
+
+static struct spi_driver kxsd9_spi_driver = {
+	.driver = {
+		.name = "kxsd9",
+	},
+	.probe = kxsd9_spi_probe,
+	.remove = kxsd9_spi_remove,
+	.id_table = kxsd9_spi_id,
+};
+module_spi_driver(kxsd9_spi_driver);
+
+MODULE_AUTHOR("Jonathan Cameron <jic23@kernel.org>");
+MODULE_DESCRIPTION("Kionix KXSD9 SPI driver");
+MODULE_LICENSE("GPL v2");
diff --git a/drivers/iio/accel/kxsd9.c b/drivers/iio/accel/kxsd9.c
index 1f9e9a8..e203337 100644
--- a/drivers/iio/accel/kxsd9.c
+++ b/drivers/iio/accel/kxsd9.c
@@ -18,7 +18,6 @@
 
 #include <linux/device.h>
 #include <linux/kernel.h>
-#include <linux/spi/spi.h>
 #include <linux/sysfs.h>
 #include <linux/slab.h>
 #include <linux/module.h>
@@ -26,6 +25,8 @@
 #include <linux/iio/iio.h>
 #include <linux/iio/sysfs.h>
 
+#include "kxsd9.h"
+
 #define KXSD9_REG_X		0x00
 #define KXSD9_REG_Y		0x02
 #define KXSD9_REG_Z		0x04
@@ -38,32 +39,6 @@
 #define KXSD9_REG_CTRL_B	0x0d
 #define KXSD9_REG_CTRL_A	0x0e
 
-#define KXSD9_READ(a) (0x80 | (a))
-#define KXSD9_WRITE(a) (a)
-
-#define KXSD9_STATE_RX_SIZE 2
-#define KXSD9_STATE_TX_SIZE 2
-
-struct kxsd9_transport;
-
-/**
- * struct kxsd9_transport - transport adapter for SPI or I2C
- * @trdev: transport device such as SPI or I2C
- * @write1(): function to write a byte to the device
- * @write2(): function to write two consecutive bytes to the device
- * @readval(): function to read a 16bit value from the device
- * @rx: cache aligned read buffer
- * @tx: cache aligned write buffer
- */
-struct kxsd9_transport {
-	void *trdev;
-	int (*write1) (struct kxsd9_transport *tr, u8 byte);
-	int (*write2) (struct kxsd9_transport *tr, u8 b1, u8 b2);
-	int (*readval) (struct kxsd9_transport *tr, u8 address);
-	u8 rx[KXSD9_STATE_RX_SIZE] ____cacheline_aligned;
-	u8 tx[KXSD9_STATE_TX_SIZE];
-};
-
 /**
  * struct kxsd9_state - device related storage
  * @transport:	transport for the KXSD9
@@ -98,12 +73,13 @@ static int kxsd9_write_scale(struct iio_dev *indio_dev, int micro)
 		return -EINVAL;
 
 	mutex_lock(&st->buf_lock);
-	ret = st->transport->write1(st->transport, KXSD9_READ(KXSD9_REG_CTRL_C));
-	if (ret)
+	ret = st->transport->readreg(st->transport,
+				     KXSD9_REG_CTRL_C);
+	if (ret < 0)
 		goto error_ret;
-	ret = st->transport->write2(st->transport,
-				    KXSD9_WRITE(KXSD9_REG_CTRL_C),
-				    (ret & ~KXSD9_FS_MASK) | i);
+	ret = st->transport->writereg(st->transport,
+				      KXSD9_REG_CTRL_C,
+				      (ret & ~KXSD9_FS_MASK) | i);
 error_ret:
 	mutex_unlock(&st->buf_lock);
 	return ret;
@@ -115,7 +91,9 @@ static int kxsd9_read(struct iio_dev *indio_dev, u8 address)
 	struct kxsd9_state *st = iio_priv(indio_dev);
 
 	mutex_lock(&st->buf_lock);
-	ret = st->transport->readval(st->transport, KXSD9_READ(address));
+	ret = st->transport->readval(st->transport, address);
+	/* Only 12 bits are valid */
+	ret &= 0xfff0;
 	mutex_unlock(&st->buf_lock);
 	return ret;
 }
@@ -165,8 +143,9 @@ static int kxsd9_read_raw(struct iio_dev *indio_dev,
 		ret = IIO_VAL_INT;
 		break;
 	case IIO_CHAN_INFO_SCALE:
-		ret = st->transport->write1(st->transport, KXSD9_READ(KXSD9_REG_CTRL_C));
-		if (ret)
+		ret = st->transport->readreg(st->transport,
+					     KXSD9_REG_CTRL_C);
+		if (ret < 0)
 			goto error_ret;
 		*val = 0;
 		*val2 = kxsd9_micro_scales[ret & KXSD9_FS_MASK];
@@ -218,9 +197,9 @@ static const struct iio_info kxsd9_info = {
 	.driver_module = THIS_MODULE,
 };
 
-static int kxsd9_common_probe(struct device *parent,
-			      struct kxsd9_transport *transport,
-			      const char *name)
+int kxsd9_common_probe(struct device *parent,
+		       struct kxsd9_transport *transport,
+		       const char *name)
 {
 	struct iio_dev *indio_dev;
 	struct kxsd9_state *st;
@@ -251,8 +230,9 @@ static int kxsd9_common_probe(struct device *parent,
 
 	return 0;
 }
+EXPORT_SYMBOL(kxsd9_common_probe);
 
-static int kxsd9_common_remove(struct device *parent)
+int kxsd9_common_remove(struct device *parent)
 {
 	struct iio_dev *indio_dev = dev_get_drvdata(parent);
 
@@ -260,93 +240,8 @@ static int kxsd9_common_remove(struct device *parent)
 
 	return 0;
 }
-
-static int kxsd9_spi_write1(struct kxsd9_transport *tr, u8 byte)
-{
-	struct spi_device *spi = tr->trdev;
-
-	return spi_w8r8(spi, byte);
-}
-
-static int kxsd9_spi_write2(struct kxsd9_transport *tr, u8 b1, u8 b2)
-{
-	struct spi_device *spi = tr->trdev;
-
-	tr->tx[0] = b1;
-	tr->tx[1] = b2;
-	return spi_write(spi, tr->tx, 2);
-}
-
-static int kxsd9_spi_readval(struct kxsd9_transport *tr, u8 address)
-{
-	struct spi_device *spi = tr->trdev;
-	struct spi_transfer xfers[] = {
-		{
-			.bits_per_word = 8,
-			.len = 1,
-			.delay_usecs = 200,
-			.tx_buf = tr->tx,
-		}, {
-			.bits_per_word = 8,
-			.len = 2,
-			.rx_buf = tr->rx,
-		},
-	};
-	int ret;
-
-	tr->tx[0] = address;
-	ret = spi_sync_transfer(spi, xfers, ARRAY_SIZE(xfers));
-	if (!ret)
-		ret = (((u16)(tr->rx[0])) << 8) | (tr->rx[1] & 0xF0);
-	return ret;
-}
-
-static int kxsd9_spi_probe(struct spi_device *spi)
-{
-	struct kxsd9_transport *transport;
-	int ret;
-
-	transport = devm_kzalloc(&spi->dev, sizeof(*transport), GFP_KERNEL);
-	if (!transport)
-		return -ENOMEM;
-
-	transport->trdev = spi;
-	transport->write1 = kxsd9_spi_write1;
-	transport->write2 = kxsd9_spi_write2;
-	transport->readval = kxsd9_spi_readval;
-	spi->mode = SPI_MODE_0;
-	spi_setup(spi);
-
-	ret = kxsd9_common_probe(&spi->dev,
-				 transport,
-				 spi_get_device_id(spi)->name);
-	if (ret)
-		return ret;
-
-	return 0;
-}
-
-static int kxsd9_spi_remove(struct spi_device *spi)
-{
-	return kxsd9_common_remove(&spi->dev);
-}
-
-static const struct spi_device_id kxsd9_spi_id[] = {
-	{"kxsd9", 0},
-	{ },
-};
-MODULE_DEVICE_TABLE(spi, kxsd9_spi_id);
-
-static struct spi_driver kxsd9_spi_driver = {
-	.driver = {
-		.name = "kxsd9",
-	},
-	.probe = kxsd9_spi_probe,
-	.remove = kxsd9_spi_remove,
-	.id_table = kxsd9_spi_id,
-};
-module_spi_driver(kxsd9_spi_driver);
+EXPORT_SYMBOL(kxsd9_common_remove);
 
 MODULE_AUTHOR("Jonathan Cameron <jic23@kernel.org>");
-MODULE_DESCRIPTION("Kionix KXSD9 SPI driver");
+MODULE_DESCRIPTION("Kionix KXSD9 driver");
 MODULE_LICENSE("GPL v2");
diff --git a/drivers/iio/accel/kxsd9.h b/drivers/iio/accel/kxsd9.h
new file mode 100644
index 0000000..28845c3
--- /dev/null
+++ b/drivers/iio/accel/kxsd9.h
@@ -0,0 +1,32 @@
+#include <linux/device.h>
+#include <linux/kernel.h>
+
+#define KXSD9_STATE_RX_SIZE 2
+#define KXSD9_STATE_TX_SIZE 2
+
+struct kxsd9_transport;
+
+/**
+ * struct kxsd9_transport - transport adapter for SPI or I2C
+ * @trdev: transport device such as SPI or I2C
+ * @readreg(): function to read a byte from an address in the device
+ * @writereg(): function to write a byte to an address in the device
+ * @write2(): function to write two consecutive bytes to the device
+ * @readval(): function to read a 16bit value from the device
+ * @rx: cache aligned read buffer
+ * @tx: cache aligned write buffer
+ */
+struct kxsd9_transport {
+	void *trdev;
+	int (*readreg) (struct kxsd9_transport *tr, u8 address);
+	int (*writereg) (struct kxsd9_transport *tr, u8 address, u8 val);
+	int (*write2) (struct kxsd9_transport *tr, u8 b1, u8 b2);
+	int (*readval) (struct kxsd9_transport *tr, u8 address);
+	u8 rx[KXSD9_STATE_RX_SIZE] ____cacheline_aligned;
+	u8 tx[KXSD9_STATE_TX_SIZE];
+};
+
+int kxsd9_common_probe(struct device *parent,
+		       struct kxsd9_transport *transport,
+		       const char *name);
+int kxsd9_common_remove(struct device *parent);