power: battery: Generic battery driver using IIO

Driver to allow use of the ADC drivers supported by the IIO
subsystem for battery status monitoring. Connecting this
driver to the relevant IIO device requires registration of
the appropriate iio_map structure array by the IIO device
driver (usually from platform data).  If specified the driver
will also make use of a gpio to provide interrupt driven
notification that the battery is fully charged.

In last version:
Addressed concerns raised by lars:
a. made the adc_bat per device.
b. get the IIO channel using hardcoded channel names.
c. Minor issues related to gpio_is_valid and some code
   refactoring.

In V1:
Addressed concerns raised by Anton:
a. changed the struct name to gab(generic adc battery).
b. Added some functions to neaten the code.
c. Some minor coding guidelines changes.
d. Used the latest function introduce by lars:
   iio_read_channel_processed to streamline the code.

In V2:
Addressed concerns by lars:
a. No need of allocating memory for channels.Make it array.
b. Code restructring, coding style and following kernel guidelines changes
   suggested by him.

In V3:
Addressed conerns by Anton:
a. Added the copyright.
b. Coding guidelines changes suggested by him.
c. Added Makefile and Kconfig
Signed-off-by: anish kumar <anish198519851985@gmail.com>
Acked-by: Anton Vorontsov <cbouatmailru@gmail.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

drivers/power/Kconfig

@@ -29,6 +29,13 @@ config APM_POWER
 	  Say Y here to enable support APM status emulation using
 	  battery class devices.
 
+config GENERIC_ADC_BATTERY
+	tristate "Generic battery support using IIO"
+	depends on IIO
+	help
+	  Say Y here to enable support for the generic battery driver
+	  which uses IIO framework to read adc.
+
 config MAX8925_POWER
 	tristate "MAX8925 battery charger support"
 	depends on MFD_MAX8925

drivers/power/Makefile

@@ -5,6 +5,7 @@ power_supply-$(CONFIG_SYSFS)		+= power_supply_sysfs.o
 power_supply-$(CONFIG_LEDS_TRIGGERS)	+= power_supply_leds.o
 
 obj-$(CONFIG_POWER_SUPPLY)	+= power_supply.o
+obj-$(CONFIG_GENERIC_ADC_BATTERY)	+= generic-adc-battery.o
 
 obj-$(CONFIG_PDA_POWER)		+= pda_power.o
 obj-$(CONFIG_APM_POWER)		+= apm_power.o

include/linux/power/generic-adc-battery.h

+/*
+ * Copyright (C) 2012, Anish Kumar <anish198519851985@gmail.com>
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#ifndef GENERIC_ADC_BATTERY_H
+#define GENERIC_ADC_BATTERY_H
+
+/**
+ * struct gab_platform_data - platform_data for generic adc iio battery driver.
+ * @battery_info:         recommended structure to specify static power supply
+ *			   parameters
+ * @cal_charge:           calculate charge level.
+ * @gpio_charge_finished: gpio for the charger.
+ * @gpio_inverted:        Should be 1 if the GPIO is active low otherwise 0
+ * @jitter_delay:         delay required after the interrupt to check battery
+ *			  status.Default set is 10ms.
+ */
+struct gab_platform_data {
+	struct power_supply_info battery_info;
+	int	(*cal_charge)(long value);
+	int	gpio_charge_finished;
+	bool	gpio_inverted;
+	int     jitter_delay;
+};
+
+#endif /* GENERIC_ADC_BATTERY_H */