Date:	Sat, 08 Sep 2012 13:00:29 +0530
From:	anish kumar <anish198519851985@...il.com>
To:	Lars-Peter Clausen <lars@...afoo.de>
Cc:	jic23@....ac.uk, linux-iio@...r.kernel.org, cbou@...l.ru,
	dwmw2@...radead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] [RFC]power: battery: Generic battery driver using IIO

On Fri, 2012-09-07 at 10:49 +0200, Lars-Peter Clausen wrote:
> On 09/02/2012 05:39 PM, anish kumar wrote:
> > From: anish kumar <anish198519851985@...il.com>
> > 
> > This patch is to use IIO to write a generic batttery driver.
> > There are some inherent assumptions here:
> > 1.User is having both main battery and backup battery.
> > 2.Both batteries use same channel to get the information.
> > 
> 
> Hi thanks for stepping up to take care of this and sorry for the late reply.
Thanks to you.
> 
> > Signed-off-by: anish kumar <anish198519851985@...il.com>
> > ---
> [...]
> > +
> > +struct generic_adc_bat {
> > +	struct power_supply		psy;
> > +	struct iio_channel		*channels;
> > +	int				channel_index;
> > +};
> > +
> > +struct generic_bat {
> > +	struct generic_adc_bat bat[BAT_MAX];
> > +	struct generic_platform_data	pdata;
> > +	int				volt_value;
> > +	int				cur_value;
> > +	unsigned int			timestamp;
> > +	int				level;
> > +	int				status;
> > +	int				cable_plugged:1;
> > +};
> > +
> > +static struct generic_bat generic_bat = {
> > +	.bat[MAIN_BAT] = {
> > +		.psy.name = "main-bat",
> > +	},
> > +	.bat[BACKUP_BAT] = {
> > +		.psy.name = "backup-bat",
> > +	},
> > +};
> 
> This should be per device. I'd also just use one power_supply per device. If
> somebody has multiple batteries in their system they can register multiple
> devices. This should make the driver more flexible.
Yes makes sense of having one driver/device and if someone has more
devices to register than it can be done by registering multiple devices
with different platform data.
> 
> > +
> > +static struct delayed_work bat_work;
> 
> This should also go into the generic_bat struct.
right.
> 
>  +
> > +static void generic_adc_bat_ext_power_changed(struct power_supply *psy)
> > +{
> > +	schedule_delayed_work(&bat_work,
> > +			msecs_to_jiffies(JITTER_DELAY));
> > +}
> > +
> > +static enum power_supply_property generic_adc_main_bat_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,
> > +};
> 
> It probably make sense to create this at runtime, depending on which kind of
> IIO channels are provided. E.g. for VOLTAGE_NOW/CURRENT_NOW.
Yes, something like
pdata->voltage_channel/pdata->current_channel/pdata->power_channel and
if this property is set then register the VOLTAGE_NOW/CURRENT_NOW/POWER_
property.
> 
> [...]
> > +
> > +static int generic_adc_bat_get_property(struct power_supply *psy,
> > +		enum power_supply_property psp,
> > +		union power_supply_propval *val)
> > +{
> > +	struct generic_adc_bat *adc_bat;
> > +	struct generic_bat *bat;
> > +	int ret, scaleint, scalepart, iio_val;
> > +	long result = 0;
> > +
> > +	if (!strcmp(psy->name, "main-battery")) {
> > +		adc_bat = container_of(psy,
> > +					struct generic_adc_bat, psy);
> > +		bat = container_of(adc_bat,
> > +				struct generic_bat, bat[MAIN_BAT]);
> > +	} else if (!strcmp(psy->name, "backup-battery")) {
> > +		adc_bat = container_of(psy, struct generic_adc_bat, psy);
> > +		bat = container_of(adc_bat,
> > +				struct generic_bat, bat[BACKUP_BAT]);
> > +	} else {
> > +		/* Ideally this should never happen */
> > +		WARN_ON(1);
> > +		return -EINVAL;
> > +	}
> > +
> > +	if (!bat) {
> > +		dev_err(psy->dev, "no battery infos ?!\n");
> > +		return -EINVAL;
> > +	}
> > +	ret = iio_read_channel_raw(&adc_bat->channels[adc_bat->channel_index],
> > +			&iio_val);
> > +	ret = iio_read_channel_scale(&adc_bat->channels[adc_bat->channel_index],
> > +			&scaleint, &scalepart);
> 
> It would probably make sense to only sample if the attribute for
> VOLTAGE_NOW/CURRENT_NOW property is read.
right.
> 
> [...]
> 
> > +
> > +	switch (psp) {
> > +	case POWER_SUPPLY_PROP_STATUS:
> > +		if (bat->pdata.gpio_charge_finished < 0)
> > +			val->intval = bat->level == 100000 ?
> > +				POWER_SUPPLY_STATUS_FULL : bat->status;
> > +		else
> > +			val->intval = bat->status;
> > +		return 0;
> > +	case POWER_SUPPLY_PROP_CHARGE_EMPTY_DESIGN:
> > +		val->intval = 0;
> > +		return 0;
> > +	case POWER_SUPPLY_PROP_CHARGE_NOW:
> > +		val->intval = bat->pdata.cal_charge(result);
> > +		return 0;
> > +	case POWER_SUPPLY_PROP_VOLTAGE_NOW:
> > +		val->intval = result;
> > +		return 0;
> > +	case POWER_SUPPLY_PROP_CURRENT_NOW:
> > +		val->intval = result;
> > +		return 0;
> 
> also this will return the same value for VOLTAGE_NOW and CURRENT_NOW since
> there is only one channel per battery. It might make sense to allow multiple
> channels per battery, one reporting current one voltage and also one for power.
absolutely makes sense.
> 
> 
> > +	case POWER_SUPPLY_PROP_TECHNOLOGY:
> > +		val->intval = bat->pdata.battery_info.technology;
> > +		break;
> > +	case POWER_SUPPLY_PROP_VOLTAGE_MIN_DESIGN:
> > +		val->intval = bat->pdata.battery_info.voltage_min_design;
> > +		break;
> > +	case POWER_SUPPLY_PROP_VOLTAGE_MAX_DESIGN:
> > +		val->intval = bat->pdata.battery_info.voltage_max_design;
> > +		break;
> > +	case POWER_SUPPLY_PROP_CHARGE_FULL_DESIGN:
> > +		val->intval = bat->pdata.battery_info.charge_full_design;
> > +		break;
> > +	case POWER_SUPPLY_PROP_MODEL_NAME:
> > +		val->strval = bat->pdata.battery_info.name;
> > +		break;
> > +	default:
> > +		return -EINVAL;
> > +	}
> > +	return ret;
> > +}
> > +
> [...]
> > +
> > +static int __devinit generic_adc_bat_probe(struct platform_device *pdev)
> > +{
> > +[...]
> > +
> > +	/* assuming main battery and backup battery is using the same channel */
> > +	for (i = 0; i < num_channels; i++) {
> > +		ret = iio_get_channel_type(&channels[i], &type);
> > +		if (ret < 0)
> > +			goto err_gpio;
> > +
> > +		if (type == IIO_VOLTAGE || type == IIO_CURRENT) {
> > +			for (j = 0; j < BAT_MAX; j++) {
> > +				generic_bat.bat[j].channel_index = k;
> > +				generic_bat.bat[j].channels[k] = channels[i];
> > +			}
> > +			k++;
> > +		}
> > +		continue;
> 
> continue at the end of a loop is a noop.
right.
> 
> > +	}
> > +
> > +	INIT_DELAYED_WORK(&bat_work, generic_adc_bat_work);
> > +
> > +	if (pdata->gpio_charge_finished >= 0) {
> 
> gpio_is_valid
right.
> 
> > +		ret = gpio_request(pdata->gpio_charge_finished, "charged");
> > +		if (ret)
> > +			goto err_gpio;
> > +
> > +		ret = request_irq(gpio_to_irq(pdata->gpio_charge_finished),
> > +				generic_adc_bat_charged,
> > +				IRQF_TRIGGER_RISING | IRQF_TRIGGER_FALLING,
> > +				"battery charged", NULL);
> > +		if (ret)
> > +			goto err_gpio;
> > +	}
> > +
> > +	dev_info(&pdev->dev, "successfully loaded\n");
> 
> I'd remove that message.
ok.
> 
> > +
> > +	/* Schedule timer to check current status */
> > +	schedule_delayed_work(&bat_work,
> > +			msecs_to_jiffies(JITTER_DELAY));
> > +
> > +	iio_channel_release_all(channels);
> > +
> > +	return 0;
> > +
> > +err_gpio:
> > +	iio_channel_release_all(channels);
> > +err_reg_backup:
> > +	for (i = 0; i < ARRAY_SIZE(generic_bat.bat); i++)
> > +		power_supply_unregister(&generic_bat.bat[i].psy);
> > +err_reg_main:
> > +	return ret;
> > +}
> > +
> 
> [...]
> 
> > +
> > +#ifdef CONFIG_PM
> > +static int generic_adc_bat_suspend(struct platform_device *pdev,
> > +		pm_message_t state)
> > +{
> > +	struct generic_platform_data *pdata = pdev->dev.platform_data;
> > +	struct generic_bat *bat = container_of(pdata,
> > +					struct generic_bat, pdata);
> > +
> > +	cancel_delayed_work_sync(&bat_work);
> > +	bat->status = POWER_SUPPLY_STATUS_UNKNOWN;
> > +
> > +	return 0;
> > +}
> > +
> > +static int generic_adc_bat_resume(struct platform_device *pdev)
> > +{
> > +	/* Schedule timer to check current status */
> > +	schedule_delayed_work(&bat_work,
> > +			msecs_to_jiffies(JITTER_DELAY));
> > +
> > +	return 0;
> > +}
> > +#else
> > +#define generic_adc_bat_suspend NULL
> > +#define generic_adc_bat_resume NULL
> > +#endif
> > +
> > +static struct platform_driver generic_adc_bat_driver = {
> > +	.driver		= {
> > +		.name	= "generic-adc-battery",
> > +	},
> > +	.probe		= generic_adc_bat_probe,
> > +	.remove		= generic_adc_bat_remove,
> > +	.suspend	= generic_adc_bat_suspend,
> > +	.resume		= generic_adc_bat_resume,
> 
> Use dev_pm_ops instead. Using the suspend and resume callbacks is deprecated.
makes sense.
> 
> > +};
> > +
> > +module_platform_driver(generic_adc_bat_driver);
> > +
> > +MODULE_AUTHOR("anish kumar <anish198519851985@...il.com>");
> > +MODULE_DESCRIPTION("generic battery driver using IIO");
> > +MODULE_LICENSE("GPL");
> > diff --git a/include/linux/power/generic-battery.h b/include/linux/power/generic-battery.h
> > new file mode 100644
> > index 0000000..7a43aa0
> > --- /dev/null
> > +++ b/include/linux/power/generic-battery.h
> > @@ -0,0 +1,26 @@
> > +/*
> > + * 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_BATTERY_H
> > +#define GENERIC_BATTERY_H
> > +
> > +#include <linux/power_supply.h>
> > +
> > +/**
> > + * struct generic_platform_data - platform data for generic battery
> > + * @battery_info: Information about the battery
> > + * @cal_charge: platform callback to calculate charge
> > + * @gpio_charge_finished: GPIO number used for interrupts
> > + * @gpio_inverted: Is the gpio inverted?
> > + */
> > +struct generic_platform_data {
> 
> The name might be a bit to generic ;) I'd go for
> generic_battery_platform_data or iio_battery_platform_data.
it will be iio_battery_platform_data.
> 
> > +	struct power_supply_info battery_info;
> > +	int	(*cal_charge)(long);
> > +	int	gpio_charge_finished;
> > +	int	gpio_inverted;
> > +};
> > +
> > +#endif /* GENERIC_BATTERY_H */
> 


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