Date:	Thu, 21 Oct 2010 16:52:37 +0200
From:	Lars-Peter Clausen <lars@...afoo.de>
To:	Anton Vorontsov <cbouatmailru@...il.com>
CC:	rklein@...dia.com, broonie@...nsource.wolfsonmicro.com,
	achew@...dia.com, olof@...om.net, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] POWER: Add gpio chager driver

Anton Vorontsov wrote:
> On Thu, Oct 21, 2010 at 02:25:57PM +0200, Lars-Peter Clausen wrote:
>> This patch adds a simple driver for chargers indicating their online status
>> through a GPIO pin.
>>
>> Signed-off-by: Lars-Peter Clausen <lars@...afoo.de>
> 
> I agree, the GPIO name fits better. Rhyland, are you OK with that
> driver, does it fit your needs?
> 
> Some comments down below.
> 
> [...]
>> +struct gpio_charger {
>> +	const struct gpio_charger_platform_data *pdata;
>> +	int irq;
> 
> This can be unsigned.

If the gpio has no irq or the irq could not be requested the irq fields value is
negative.

> 
>> +
>> +	struct power_supply charger;
>> +};
>> +
>> +static irqreturn_t gpio_charger_irq(int irq, void *devid)
>> +{
>> +	struct power_supply *charger = devid;
> 
> Please add an empty line here.
> 
>> +	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)
> 
> One more tab for here?
> 
I prefer one tab, but I can change it.

>> +{
>> +	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;
>> +
>> +	if (!pdata) {
>> +		dev_err(&pdev->dev, "No platform data");
>> +		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;
>> +	}
>> +
>> +	gpio_charger->irq = gpio_to_irq(pdata->gpio);
>> +	if (gpio_charger->irq >= 0) {
> 
> 0 isn't valid IRQ number. The check should be just 'if (gpio_charger->irq)'.

While it is unlikely to be used for an gpio IRQ, as far as I know 0 is a valid IRQ
number.

> 
>> +		ret = request_irq(gpio_charger->irq, gpio_charger_irq,
>> +				IRQF_TRIGGER_RISING | IRQF_TRIGGER_FALLING,
>> +				dev_name(&pdev->dev), charger);
>> +		if (ret) {
>> +			dev_warn(&pdev->dev, "Failed to request gpio irq: %d\n", ret);
>> +			gpio_charger->irq = -1;
>> +		}
>> +	}
>> +
>> +	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 >= 0)
>> +		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);
>> +	const struct gpio_charger_platform_data *pdata = gpio_charger->pdata;
>> +
>> +	power_supply_unregister(&gpio_charger->charger);
>> +
>> +	if (gpio_charger->irq >= 0)
>> +		free_irq(gpio_charger->irq, &gpio_charger->charger);
>> +	gpio_free(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 <lars@...afoo.de>");
>> +MODULE_DESCRIPTION("Driver for chargers which report their online status through a GPIO");
>> +MODULE_LICENSE("GPL");
>> +MODULE_ALIAS("platform:gpio-charger");
>> diff --git a/include/linux/power/gpio-charger.h b/include/linux/power/gpio-charger.h
>> new file mode 100644
>> index 0000000..404d5e6
>> --- /dev/null
>> +++ b/include/linux/power/gpio-charger.h
>> @@ -0,0 +1,39 @@
>> +/*
>> + *  Copyright (C) 2010, Lars-Peter Clausen <lars@...afoo.de>
>> + *
>> + *  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__
>> +
>> +/*
> 
> Should be /**
> 
>> + * 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
>> + */
>> +
> 
> No need for this empty line.
> 
>> +struct gpio_charger_platform_data {
>> +	const char *name;
>> +	enum power_supply_type type;
> 
> #include <linux/power_supply.h> is needed for this.
> 
>> +
>> +	int gpio;
>> +	int gpio_active_low;
>> +
>> +	char **supplied_to;
>> +	size_t num_supplicants;
> 
> And #include <linux/types.h> for this.
> 
>> +};
>> +
>> +#endif
> 
> Thanks!
> 

Thanks,
- Lars
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