staging: IIO: ADC: New driver for the AD7780 / AD7781 24-bit Sigma-Delta ADC

Changes since v1:

IIO: ADC: AD7780: Apply review feedback

Abort probe() with error in case platform_data is not present.
Add comment explaining power down reset (PDRST) GPIO handling
and dual function DOUT/RDY interrupt usage.

Signed-off-by: Michael Hennerich <michael.hennerich@analog.com>
Acked-by: Jonathan Cameron <jic23@cam.ac.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 30 insertions, 0 deletions

diff --git a/drivers/staging/iio/adc/ad7780.h b/drivers/staging/iio/adc/ad7780.h
new file mode 100644
index 000000000000..67e511c3d6f0
--- /dev/null
+++ b/drivers/staging/iio/adc/ad7780.h
@@ -0,0 +1,30 @@
+/*
+ * AD7780/AD7781 SPI ADC driver
+ *
+ * Copyright 2011 Analog Devices Inc.
+ *
+ * Licensed under the GPL-2.
+ */
+#ifndef IIO_ADC_AD7780_H_
+#define IIO_ADC_AD7780_H_
+
+/*
+ * TODO: struct ad7780_platform_data needs to go into include/linux/iio
+ */
+
+/* NOTE:
+ * The AD7780 doesn't feature a dedicated SPI chip select, in addition it
+ * features a dual use data out ready DOUT/RDY output.
+ * In order to avoid contentions on the SPI bus, it's therefore necessary
+ * to use spi bus locking combined with a dedicated GPIO to control the
+ * power down reset signal of the AD7780.
+ *
+ * The DOUT/RDY output must also be wired to an interrupt capable GPIO.
+ */
+
+struct ad7780_platform_data {
+	u16				vref_mv;
+	int				gpio_pdrst;
+};
+
+#endif /* IIO_ADC_AD7780_H_ */