Re: [PATCH] [RFC]power: battery: Generic battery driver using IIO

[Lars-Peter Clausen]

On 09/02/2012 05:39 PM, anish kumar wrote:
> From: anish kumar <anish198519851985@xxxxxxxxx>
> 
> 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.

> Signed-off-by: anish kumar <anish198519851985@xxxxxxxxx>
> ---
[...]
> +
> +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.

> +
> +static struct delayed_work bat_work;

This should also go into the generic_bat struct.

 +
> +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.

[...]
> +
> +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.

[...]

> +
> +	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.


> +	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.

> +	}
> +
> +	INIT_DELAYED_WORK(&bat_work, generic_adc_bat_work);
> +
> +	if (pdata->gpio_charge_finished >= 0) {

gpio_is_valid

> +		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.

> +
> +	/* 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.

> +};
> +
> +module_platform_driver(generic_adc_bat_driver);
> +
> +MODULE_AUTHOR("anish kumar <anish198519851985@xxxxxxxxx>");
> +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.

> +	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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