iio: adc: New driver for AD7280A Lithium Ion Battery Monitoring System

The AD7280A monitoring system contains all the functions required for
general purpose monitoring and maintenance of stacked
lithium ion batteries as used in hybrid electric vehicles,
battery backup applications, etc.

Changes since V1:

Make cell channels all type IIO_IN_DIFF, update documentation accordingly.
Remove unused and redundant defines.
Use SI units where applicable.
Remove unnecessary wrapper function.
Remove redundant initialization.
Add comments where requested.
Revise event handler.
Use const where applicable.

Changes since V2:

Remove redundant adc.h include file, scheduled for removal.
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>

drivers/staging/iio/Documentation/sysfs-bus-iio-adc-ad7280a

+What:		/sys/bus/iio/devices/deviceX/inY-inZ_balance_switch_en
+KernelVersion:	3.0.0
+Contact:	linux-iio@vger.kernel.org
+Description:
+		Writing 1 enables the cell balance output switch corresponding
+		to input Y. Writing 0 disables it. If the inY-inZ_balance_timer
+		is set to a none zero value, the corresponding switch will
+		enable for the programmed amount of time, before it
+		automatically disables.
+
+What:		/sys/bus/iio/devices/deviceX/inY-inZ_balance_timer
+KernelVersion:	3.0.0
+Contact:	linux-iio@vger.kernel.org
+Description:
+		The inY-inZ_balance_timer file allows the user to program
+		individual times for each cell balance output. The AD7280A
+		allows the user to set the timer to a value from 0 minutes to
+		36.9 minutes. The resolution of the timer is 71.5 sec.
+		The value written is the on-time in milliseconds. When the
+		timer value is set 0, the timer is disabled. The cell balance
+		outputs are controlled only by inY-inZ_balance_switch_en.

drivers/staging/iio/adc/Kconfig

@@ -182,6 +182,16 @@ config ADT7410
 	  Say yes here to build support for Analog Devices ADT7410
 	  temperature sensors.
 
+config AD7280
+	tristate "Analog Devices AD7280A Lithium Ion Battery Monitoring System"
+	depends on SPI
+	help
+	  Say yes here to build support for Analog Devices AD7280A
+	  Lithium Ion Battery Monitoring System.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called ad7280a
+
 config MAX1363
 	tristate "Maxim max1363 ADC driver"
 	depends on I2C

drivers/staging/iio/adc/Makefile

@@ -40,3 +40,4 @@ obj-$(CONFIG_AD7816) += ad7816.o
 obj-$(CONFIG_ADT75) += adt75.o
 obj-$(CONFIG_ADT7310) += adt7310.o
 obj-$(CONFIG_ADT7410) += adt7410.o
+obj-$(CONFIG_AD7280) += ad7280a.o

drivers/staging/iio/adc/ad7280a.h

+/*
+ * AD7280A Lithium Ion Battery Monitoring System
+ *
+ * Copyright 2011 Analog Devices Inc.
+ *
+ * Licensed under the GPL-2.
+ */
+
+#ifndef IIO_ADC_AD7280_H_
+#define IIO_ADC_AD7280_H_
+
+/*
+ * TODO: struct ad7280_platform_data needs to go into include/linux/iio
+ */
+
+#define AD7280A_ACQ_TIME_400ns			0
+#define AD7280A_ACQ_TIME_800ns			1
+#define AD7280A_ACQ_TIME_1200ns			2
+#define AD7280A_ACQ_TIME_1600ns			3
+
+#define AD7280A_CONV_AVG_DIS			0
+#define AD7280A_CONV_AVG_2			1
+#define AD7280A_CONV_AVG_4			2
+#define AD7280A_CONV_AVG_8			3
+
+#define AD7280A_ALERT_REMOVE_VIN5		(1 << 2)
+#define AD7280A_ALERT_REMOVE_VIN4_VIN5		(2 << 2)
+#define AD7280A_ALERT_REMOVE_AUX5		(1 << 0)
+#define AD7280A_ALERT_REMOVE_AUX4_AUX5		(2 << 0)
+
+struct ad7280_platform_data {
+	unsigned acquisition_time;
+	unsigned conversion_averaging;
+	unsigned chain_last_alert_ignore;
+	bool thermistor_term_en;
+};
+
+#endif /* IIO_ADC_AD7280_H_ */