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: Nanish kumar <anish198519851985@gmail.com>
Acked-by: NAnton Vorontsov <cbouatmailru@gmail.com>
Signed-off-by: NJonathan 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

drivers/power/generic-adc-battery.c

+/*
+ * Generic battery driver code using IIO
+ * Copyright (C) 2012, Anish Kumar <anish198519851985@gmail.com>
+ * based on jz4740-battery.c
+ * based on s3c_adc_battery.c
+ *
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License.  See the file COPYING in the main directory of this archive for
+ * more details.
+ *
+ */
+#include <linux/interrupt.h>
+#include <linux/platform_device.h>
+#include <linux/power_supply.h>
+#include <linux/gpio.h>
+#include <linux/err.h>
+#include <linux/timer.h>
+#include <linux/jiffies.h>
+#include <linux/errno.h>
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/iio/consumer.h>
+#include <linux/iio/types.h>
+#include <linux/power/generic-adc-battery.h>
+
+#define JITTER_DEFAULT 10 /* hope 10ms is enough */
+
+enum gab_chan_type {
+	GAB_VOLTAGE = 0,
+	GAB_CURRENT,
+	GAB_POWER,
+	GAB_MAX_CHAN_TYPE
+};
+
+/*
+ * gab_chan_name suggests the standard channel names for commonly used
+ * channel types.
+ */
+static const char *const gab_chan_name[] = {
+	[GAB_VOLTAGE]	= "voltage",
+	[GAB_CURRENT]	= "current",
+	[GAB_POWER]		= "power",
+};
+
+struct gab {
+	struct power_supply	psy;
+	struct iio_channel	*channel[GAB_MAX_CHAN_TYPE];
+	struct gab_platform_data	*pdata;
+	struct delayed_work bat_work;
+	int	level;
+	int	status;
+	bool cable_plugged;
+};
+
+static struct gab *to_generic_bat(struct power_supply *psy)
+{
+	return container_of(psy, struct gab, psy);
+}
+
+static void gab_ext_power_changed(struct power_supply *psy)
+{
+	struct gab *adc_bat = to_generic_bat(psy);
+
+	schedule_delayed_work(&adc_bat->bat_work, msecs_to_jiffies(0));
+}
+
+static const enum power_supply_property gab_props[] = {
+	POWER_SUPPLY_PROP_STATUS,
+	POWER_SUPPLY_PROP_CHARGE_FULL_DESIGN,
+	POWER_SUPPLY_PROP_CHARGE_EMPTY_DESIGN,
+	POWER_SUPPLY_PROP_CHARGE_NOW,
+	POWER_SUPPLY_PROP_VOLTAGE_NOW,
+	POWER_SUPPLY_PROP_CURRENT_NOW,
+	POWER_SUPPLY_PROP_TECHNOLOGY,
+	POWER_SUPPLY_PROP_VOLTAGE_MIN_DESIGN,
+	POWER_SUPPLY_PROP_VOLTAGE_MAX_DESIGN,
+	POWER_SUPPLY_PROP_MODEL_NAME,
+};
+
+/*
+ * This properties are set based on the received platform data and this
+ * should correspond one-to-one with enum chan_type.
+ */
+static const enum power_supply_property gab_dyn_props[] = {
+	POWER_SUPPLY_PROP_VOLTAGE_NOW,
+	POWER_SUPPLY_PROP_CURRENT_NOW,
+	POWER_SUPPLY_PROP_POWER_NOW,
+};
+
+static bool gab_charge_finished(struct gab *adc_bat)
+{
+	struct gab_platform_data *pdata = adc_bat->pdata;
+	bool ret = gpio_get_value(pdata->gpio_charge_finished);
+	bool inv = pdata->gpio_inverted;
+
+	if (!gpio_is_valid(pdata->gpio_charge_finished))
+		return false;
+	return ret ^ inv;
+}
+
+static int gab_get_status(struct gab *adc_bat)
+{
+	struct gab_platform_data *pdata = adc_bat->pdata;
+	struct power_supply_info *bat_info;
+
+	bat_info = &pdata->battery_info;
+	if (adc_bat->level == bat_info->charge_full_design)
+		return POWER_SUPPLY_STATUS_FULL;
+	return adc_bat->status;
+}
+
+static enum gab_chan_type gab_prop_to_chan(enum power_supply_property psp)
+{
+	switch (psp) {
+	case POWER_SUPPLY_PROP_POWER_NOW:
+		return GAB_POWER;
+	case POWER_SUPPLY_PROP_VOLTAGE_NOW:
+		return GAB_VOLTAGE;
+	case POWER_SUPPLY_PROP_CURRENT_NOW:
+		return GAB_CURRENT;
+	default:
+		WARN_ON(1);
+		break;
+	}
+	return GAB_POWER;
+}
+
+static int read_channel(struct gab *adc_bat, enum power_supply_property psp,
+		int *result)
+{
+	int ret;
+	int chan_index;
+
+	chan_index = gab_prop_to_chan(psp);
+	ret = iio_read_channel_processed(adc_bat->channel[chan_index],
+			result);
+	if (ret < 0)
+		pr_err("read channel error\n");
+	return ret;
+}
+
+static int gab_get_property(struct power_supply *psy,
+		enum power_supply_property psp, union power_supply_propval *val)
+{
+	struct gab *adc_bat;
+	struct gab_platform_data *pdata;
+	struct power_supply_info *bat_info;
+	int result = 0;
+	int ret = 0;
+
+	adc_bat = to_generic_bat(psy);
+	if (!adc_bat) {
+		dev_err(psy->dev, "no battery infos ?!\n");
+		return -EINVAL;
+	}
+	pdata = adc_bat->pdata;
+	bat_info = &pdata->battery_info;
+
+	switch (psp) {
+	case POWER_SUPPLY_PROP_STATUS:
+		gab_get_status(adc_bat);
+		break;
+	case POWER_SUPPLY_PROP_CHARGE_EMPTY_DESIGN:
+		val->intval = 0;
+		break;
+	case POWER_SUPPLY_PROP_CHARGE_NOW:
+		val->intval = pdata->cal_charge(result);
+		break;
+	case POWER_SUPPLY_PROP_VOLTAGE_NOW:
+	case POWER_SUPPLY_PROP_CURRENT_NOW:
+	case POWER_SUPPLY_PROP_POWER_NOW:
+		ret = read_channel(adc_bat, psp, &result);
+		if (ret < 0)
+			goto err;
+		val->intval = result;
+		break;
+	case POWER_SUPPLY_PROP_TECHNOLOGY:
+		val->intval = bat_info->technology;
+		break;
+	case POWER_SUPPLY_PROP_VOLTAGE_MIN_DESIGN:
+		val->intval = bat_info->voltage_min_design;
+		break;
+	case POWER_SUPPLY_PROP_VOLTAGE_MAX_DESIGN:
+		val->intval = bat_info->voltage_max_design;
+		break;
+	case POWER_SUPPLY_PROP_CHARGE_FULL_DESIGN:
+		val->intval = bat_info->charge_full_design;
+		break;
+	case POWER_SUPPLY_PROP_MODEL_NAME:
+		val->strval = bat_info->name;
+		break;
+	default:
+		return -EINVAL;
+	}
+err:
+	return ret;
+}
+
+static void gab_work(struct work_struct *work)
+{
+	struct gab *adc_bat;
+	struct gab_platform_data *pdata;
+	struct delayed_work *delayed_work;
+	bool is_plugged;
+	int status;
+
+	delayed_work = container_of(work, struct delayed_work, work);
+	adc_bat = container_of(delayed_work, struct gab, bat_work);
+	pdata = adc_bat->pdata;
+	status = adc_bat->status;
+
+	is_plugged = power_supply_am_i_supplied(&adc_bat->psy);
+	adc_bat->cable_plugged = is_plugged;
+
+	if (!is_plugged)
+		adc_bat->status =  POWER_SUPPLY_STATUS_DISCHARGING;
+	else if (gab_charge_finished(adc_bat))
+		adc_bat->status = POWER_SUPPLY_STATUS_NOT_CHARGING;
+	else
+		adc_bat->status = POWER_SUPPLY_STATUS_CHARGING;
+
+	if (status != adc_bat->status)
+		power_supply_changed(&adc_bat->psy);
+}
+
+static irqreturn_t gab_charged(int irq, void *dev_id)
+{
+	struct gab *adc_bat = dev_id;
+	struct gab_platform_data *pdata = adc_bat->pdata;
+	int delay;
+
+	delay = pdata->jitter_delay ? pdata->jitter_delay : JITTER_DEFAULT;
+	schedule_delayed_work(&adc_bat->bat_work,
+			msecs_to_jiffies(delay));
+	return IRQ_HANDLED;
+}
+
+static int __devinit gab_probe(struct platform_device *pdev)
+{
+	struct gab *adc_bat;
+	struct power_supply *psy;
+	struct gab_platform_data *pdata = pdev->dev.platform_data;
+	enum power_supply_property *properties;
+	int ret = 0;
+	int chan;
+	int index = 0;
+
+	adc_bat = devm_kzalloc(&pdev->dev, sizeof(*adc_bat), GFP_KERNEL);
+	if (!adc_bat) {
+		dev_err(&pdev->dev, "failed to allocate memory\n");
+		return -ENOMEM;
+	}
+
+	psy = &adc_bat->psy;
+	psy->name = pdata->battery_info.name;
+
+	/* bootup default values for the battery */
+	adc_bat->cable_plugged = false;
+	adc_bat->status = POWER_SUPPLY_STATUS_DISCHARGING;
+	psy->type = POWER_SUPPLY_TYPE_BATTERY;
+	psy->get_property = gab_get_property;
+	psy->external_power_changed = gab_ext_power_changed;
+	adc_bat->pdata = pdata;
+
+	/* calculate the total number of channels */
+	chan = ARRAY_SIZE(gab_chan_name);
+
+	/*
+	 * copying the static properties and allocating extra memory for holding
+	 * the extra configurable properties received from platform data.
+	 */
+	psy->properties = kcalloc(ARRAY_SIZE(gab_props) +
+					ARRAY_SIZE(gab_chan_name),
+					sizeof(*psy->properties), GFP_KERNEL);
+	if (!psy->properties) {
+		ret = -ENOMEM;
+		goto first_mem_fail;
+	}
+
+	memcpy(psy->properties, gab_props, sizeof(gab_props));
+	properties = psy->properties + sizeof(gab_props);
+
+	/*
+	 * getting channel from iio and copying the battery properties
+	 * based on the channel supported by consumer device.
+	 */
+	for (chan = 0; chan < ARRAY_SIZE(gab_chan_name); chan++) {
+		adc_bat->channel[chan] = iio_channel_get(dev_name(&pdev->dev),
+						gab_chan_name[chan]);
+		if (IS_ERR(adc_bat->channel[chan])) {
+			ret = PTR_ERR(adc_bat->channel[chan]);
+		} else {
+			/* copying properties for supported channels only */
+			memcpy(properties + sizeof(*(psy->properties)) * index,
+					&gab_dyn_props[chan],
+					sizeof(gab_dyn_props[chan]));
+			index++;
+		}
+	}
+
+	/* none of the channels are supported so let's bail out */
+	if (index == ARRAY_SIZE(gab_chan_name))
+		goto second_mem_fail;
+
+	/*
+	 * Total number of properties is equal to static properties
+	 * plus the dynamic properties.Some properties may not be set
+	 * as come channels may be not be supported by the device.So
+	 * we need to take care of that.
+	 */
+	psy->num_properties = ARRAY_SIZE(gab_props) + index;
+
+	ret = power_supply_register(&pdev->dev, psy);
+	if (ret)
+		goto err_reg_fail;
+
+	INIT_DELAYED_WORK(&adc_bat->bat_work, gab_work);
+
+	if (gpio_is_valid(pdata->gpio_charge_finished)) {
+		int irq;
+		ret = gpio_request(pdata->gpio_charge_finished, "charged");
+		if (ret)
+			goto gpio_req_fail;
+
+		irq = gpio_to_irq(pdata->gpio_charge_finished);
+		ret = request_any_context_irq(irq, gab_charged,
+				IRQF_TRIGGER_RISING | IRQF_TRIGGER_FALLING,
+				"battery charged", adc_bat);
+		if (ret)
+			goto err_gpio;
+	}
+
+	platform_set_drvdata(pdev, adc_bat);
+
+	/* Schedule timer to check current status */
+	schedule_delayed_work(&adc_bat->bat_work,
+			msecs_to_jiffies(0));
+	return 0;
+
+err_gpio:
+	gpio_free(pdata->gpio_charge_finished);
+gpio_req_fail:
+	power_supply_unregister(psy);
+err_reg_fail:
+	for (chan = 0; ARRAY_SIZE(gab_chan_name); chan++)
+		iio_channel_release(adc_bat->channel[chan]);
+second_mem_fail:
+	kfree(psy->properties);
+first_mem_fail:
+	return ret;
+}
+
+static int __devexit gab_remove(struct platform_device *pdev)
+{
+	int chan;
+	struct gab *adc_bat = platform_get_drvdata(pdev);
+	struct gab_platform_data *pdata = adc_bat->pdata;
+
+	power_supply_unregister(&adc_bat->psy);
+
+	if (gpio_is_valid(pdata->gpio_charge_finished)) {
+		free_irq(gpio_to_irq(pdata->gpio_charge_finished), adc_bat);
+		gpio_free(pdata->gpio_charge_finished);
+	}
+
+	for (chan = 0; ARRAY_SIZE(gab_chan_name); chan++)
+		iio_channel_release(adc_bat->channel[chan]);
+
+	kfree(adc_bat->psy.properties);
+	cancel_delayed_work(&adc_bat->bat_work);
+	return 0;
+}
+
+#ifdef CONFIG_PM
+static int gab_suspend(struct device *dev)
+{
+	struct gab *adc_bat = dev_get_drvdata(dev);
+
+	cancel_delayed_work_sync(&adc_bat->bat_work);
+	adc_bat->status = POWER_SUPPLY_STATUS_UNKNOWN;
+	return 0;
+}
+
+static int gab_resume(struct device *dev)
+{
+	struct gab *adc_bat = dev_get_drvdata(dev);
+	struct gab_platform_data *pdata = adc_bat->pdata;
+	int delay;
+
+	delay = pdata->jitter_delay ? pdata->jitter_delay : JITTER_DEFAULT;
+
+	/* Schedule timer to check current status */
+	schedule_delayed_work(&adc_bat->bat_work,
+			msecs_to_jiffies(delay));
+	return 0;
+}
+
+static const struct dev_pm_ops gab_pm_ops = {
+	.suspend        = gab_suspend,
+	.resume         = gab_resume,
+};
+
+#define GAB_PM_OPS       (&gab_pm_ops)
+#else
+#define GAB_PM_OPS       (NULL)
+#endif
+
+static struct platform_driver gab_driver = {
+	.driver		= {
+		.name	= "generic-adc-battery",
+		.owner	= THIS_MODULE,
+		.pm	= GAB_PM_OPS
+	},
+	.probe		= gab_probe,
+	.remove		= __devexit_p(gab_remove),
+};
+module_platform_driver(gab_driver);
+
+MODULE_AUTHOR("anish kumar <anish198519851985@gmail.com>");
+MODULE_DESCRIPTION("generic battery driver using IIO");
+MODULE_LICENSE("GPL");

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 */