iio:imu: Add support for the ADIS16480 and similar IMUs

This patch adds support for the ADIS16375, ADIS16480, ADIS16485, ADIS16488 6
degree to 10 degree of freedom IMUs.
Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

drivers/iio/imu/Kconfig

+#
+# IIO imu drivers configuration
+#
+menu "Inertial measurement units"
+
+config ADIS16480
+	tristate "Analog Devices ADIS16480 and similar IMU driver"
+	depends on SPI
+	select IIO_ADIS_LIB
+	select IIO_ADIS_LIB_BUFFER if IIO_BUFFER
+	help
+	  Say yes here to build support for Analog Devices ADIS16375, ADIS16480,
+	  ADIS16485, ADIS16488 inertial sensors.
+
+endmenu
+
 config IIO_ADIS_LIB
 	tristate
 	help

drivers/iio/imu/Makefile

@@ -2,6 +2,8 @@
 # Makefile for Inertial Measurement Units
 #
 
+obj-$(CONFIG_ADIS16480) += adis16480.o
+
 adis_lib-y += adis.o
 adis_lib-$(CONFIG_IIO_ADIS_LIB_BUFFER) += adis_trigger.o
 adis_lib-$(CONFIG_IIO_ADIS_LIB_BUFFER) += adis_buffer.o

drivers/iio/imu/adis.c

@@ -238,6 +238,9 @@ int adis_enable_irq(struct adis *adis, bool enable)
 	int ret = 0;
 	uint16_t msc;
 
+	if (adis->data->enable_irq)
+		return adis->data->enable_irq(adis, enable);
+
 	ret = adis_read_reg_16(adis, adis->data->msc_ctrl_reg, &msc);
 	if (ret)
 		goto error_ret;

include/linux/iio/imu/adis.h

@@ -20,6 +20,8 @@
 #define ADIS_PAGE_SIZE 0x80
 #define ADIS_REG_PAGE_ID 0x00
 
+struct adis;
+
 /**
  * struct adis_data - ADIS chip variant specific data
  * @read_delay: SPI delay for read operations in us
@@ -44,6 +46,8 @@ struct adis_data {
 	const char * const *status_error_msgs;
 	unsigned int status_error_mask;
 
+	int (*enable_irq)(struct adis *adis, bool enable);
+
 	bool has_paging;
 };