power_supply: Add gpio charger driver

This patch adds a simple driver for chargers indicating their online
status through a GPIO pin.

Signed-off-by: Lars-Peter Clausen <[e-mail]>
Signed-off-by: Anton Vorontsov <[e-mail]>

drivers/power/Kconfig

···
 	help
 	  Say Y here to enable support for TWL4030 Battery Charge Interface.
 
+config CHARGER_GPIO
+	tristate "GPIO charger"
+	depends on GPIOLIB
+	help
+	  Say Y to include support for chargers which report their online status
+	  through a GPIO pin.
+
+	  This driver can be build as a module. If so, the module will be
+	  called gpio-charger.
+
 endif # POWER_SUPPLY

drivers/power/Makefile

···
 obj-$(CONFIG_BATTERY_INTEL_MID)	+= intel_mid_battery.o
 obj-$(CONFIG_CHARGER_ISP1704)	+= isp1704_charger.o
 obj-$(CONFIG_CHARGER_TWL4030)	+= twl4030_charger.o
+obj-$(CONFIG_CHARGER_GPIO)	+= gpio-charger.o

drivers/power/gpio-charger.c

···
+/*
+ *  Copyright (C) 2010, Lars-Peter Clausen <[e-mail]>
+ *  Driver for chargers which report their online status through a GPIO pin
+ *
+ *  This program is free software; you can redistribute it and/or modify it
+ *  under  the terms of the GNU General  Public License as published by the
+ *  Free Software Foundation;  either version 2 of the License, or (at your
+ *  option) any later version.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  675 Mass Ave, Cambridge, MA 02139, USA.
+ *
+ */
+
+#include <linux/device.h>
+#include <linux/gpio.h>
+#include <linux/init.h>
+#include <linux/interrupt.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/power_supply.h>
+#include <linux/slab.h>
+
+#include <linux/power/gpio-charger.h>
+
+struct gpio_charger {
+	const struct gpio_charger_platform_data *pdata;
+	unsigned int irq;
+
+	struct power_supply charger;
+};
+
+static irqreturn_t gpio_charger_irq(int irq, void *devid)
+{
+	struct power_supply *charger = devid;
+
+	power_supply_changed(charger);
+
+	return IRQ_HANDLED;
+}
+
+static inline struct gpio_charger *psy_to_gpio_charger(struct power_supply *psy)
+{
+	return container_of(psy, struct gpio_charger, charger);
+}
+
+static int gpio_charger_get_property(struct power_supply *psy,
+		enum power_supply_property psp, union power_supply_propval *val)
+{
+	struct gpio_charger *gpio_charger = psy_to_gpio_charger(psy);
+	const struct gpio_charger_platform_data *pdata = gpio_charger->pdata;
+
+	switch (psp) {
+	case POWER_SUPPLY_PROP_ONLINE:
+		val->intval = gpio_get_value(pdata->gpio);
+		val->intval ^= pdata->gpio_active_low;
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+static enum power_supply_property gpio_charger_properties[] = {
+	POWER_SUPPLY_PROP_ONLINE,
+};
+
+static int __devinit gpio_charger_probe(struct platform_device *pdev)
+{
+	const struct gpio_charger_platform_data *pdata = pdev->dev.platform_data;
+	struct gpio_charger *gpio_charger;
+	struct power_supply *charger;
+	int ret;
+	int irq;
+
+	if (!pdata) {
+		dev_err(&pdev->dev, "No platform data\n");
+		return -EINVAL;
+	}
+
+	if (!gpio_is_valid(pdata->gpio)) {
+		dev_err(&pdev->dev, "Invalid gpio pin\n");
+		return -EINVAL;
+	}
+
+	gpio_charger = kzalloc(sizeof(*gpio_charger), GFP_KERNEL);
+
+	charger = &gpio_charger->charger;
+
+	charger->name = pdata->name;
+	charger->type = pdata->type;
+	charger->properties = gpio_charger_properties;
+	charger->num_properties = ARRAY_SIZE(gpio_charger_properties);
+	charger->get_property  = gpio_charger_get_property;
+	charger->supplied_to = pdata->supplied_to;
+	charger->num_supplicants = pdata->num_supplicants;
+
+	ret = gpio_request(pdata->gpio, dev_name(&pdev->dev));
+	if (ret) {
+		dev_err(&pdev->dev, "Failed to request gpio pin: %d\n", ret);
+		goto err_free;
+	}
+	ret = gpio_direction_input(pdata->gpio);
+	if (ret) {
+		dev_err(&pdev->dev, "Failed to set gpio to input: %d\n", ret);
+		goto err_gpio_free;
+	}
+
+	irq = gpio_to_irq(pdata->gpio);
+	if (irq > 0) {
+		ret = request_irq(irq, gpio_charger_irq,
+				IRQF_TRIGGER_RISING | IRQF_TRIGGER_FALLING,
+				dev_name(&pdev->dev), charger);
+		if (ret)
+			dev_warn(&pdev->dev, "Failed to request irq: %d\n", ret);
+		else
+			gpio_charger->irq = irq;
+	}
+
+	gpio_charger->pdata = pdata;
+
+	ret = power_supply_register(&pdev->dev, charger);
+	if (ret < 0) {
+		dev_err(&pdev->dev, "Failed to register power supply: %d\n", ret);
+		goto err_irq_free;
+	}
+
+	platform_set_drvdata(pdev, gpio_charger);
+
+	return 0;
+
+err_irq_free:
+	if (gpio_charger->irq)
+		free_irq(gpio_charger->irq, charger);
+err_gpio_free:
+	gpio_free(pdata->gpio);
+err_free:
+	kfree(gpio_charger);
+	return ret;
+}
+
+static int __devexit gpio_charger_remove(struct platform_device *pdev)
+{
+	struct gpio_charger *gpio_charger = platform_get_drvdata(pdev);
+
+	power_supply_unregister(&gpio_charger->charger);
+
+	if (gpio_charger->irq)
+		free_irq(gpio_charger->irq, &gpio_charger->charger);
+	gpio_free(gpio_charger->pdata->gpio);
+
+	platform_set_drvdata(pdev, NULL);
+	kfree(gpio_charger);
+
+	return 0;
+}
+
+static struct platform_driver gpio_charger_driver = {
+	.probe = gpio_charger_probe,
+	.remove = __devexit_p(gpio_charger_remove),
+	.driver = {
+		.name = "gpio-charger",
+		.owner = THIS_MODULE,
+	},
+};
+
+static int __init gpio_charger_init(void)
+{
+	return platform_driver_register(&gpio_charger_driver);
+}
+module_init(gpio_charger_init);
+
+static void __exit gpio_charger_exit(void)
+{
+	platform_driver_unregister(&gpio_charger_driver);
+}
+module_exit(gpio_charger_exit);
+
+MODULE_AUTHOR("Lars-Peter Clausen <[e-mail]>");
+MODULE_DESCRIPTION("Driver for chargers which report their online status through a GPIO");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("platform:gpio-charger");

include/linux/power/gpio-charger.h

···
+/*
+ *  Copyright (C) 2010, Lars-Peter Clausen <[e-mail]>
+ *
+ *  This program is free software; you can redistribute it and/or modify it
+ *  under  the terms of the GNU General  Public License as published by the
+ *  Free Software Foundation;  either version 2 of the License, or (at your
+ *  option) any later version.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  675 Mass Ave, Cambridge, MA 02139, USA.
+ *
+ */
+
+#ifndef __LINUX_POWER_GPIO_CHARGER_H__
+#define __LINUX_POWER_GPIO_CHARGER_H__
+
+#include <linux/power_supply.h>
+#include <linux/types.h>
+
+/**
+ * struct gpio_charger_platform_data - platform_data for gpio_charger devices
+ * @name:		Name for the chargers power_supply device
+ * @type:		Type of the charger
+ * @gpio:		GPIO which is used to indicate the chargers status
+ * @gpio_active_low:	Should be set to 1 if the GPIO is active low otherwise 0
+ * @supplied_to:	Array of battery names to which this chargers supplies power
+ * @num_supplicants:	Number of entries in the supplied_to array
+ */
+struct gpio_charger_platform_data {
+	const char *name;
+	enum power_supply_type type;
+
+	int gpio;
+	int gpio_active_low;
+
+	char **supplied_to;
+	size_t num_supplicants;
+};
+
+#endif