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Date:   Wed, 20 Feb 2019 16:24:58 +0100
From:   Artur Rojek <contact@...ur-rojek.eu>
To:     Jonathan Cameron <jic23@...nel.org>
Cc:     Sebastian Reichel <sre@...nel.org>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>, linux-pm@...r.kernel.org,
        linux-iio@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, Paul Cercueil <paul@...pouillou.net>
Subject: Re: [PATCH 5/7] power: supply: add Ingenic JZ47xx battery driver.

On 2019-02-20 12:14, Jonathan Cameron wrote:
> On Sun, 17 Feb 2019 15:29:14 +0100
> Artur Rojek <contact@...ur-rojek.eu> wrote:
> 
>> Add a driver for battery present on Ingenic JZ47xx SoCs.
>> 
>> Signed-off-by: Artur Rojek <contact@...ur-rojek.eu>
> A few things inline.
> 
> thanks,
> 
> Jonathan
> 

Hi Jonathan,

Thanks for the review.

>> ---
>>  drivers/power/supply/Kconfig           |  11 ++
>>  drivers/power/supply/Makefile          |   1 +
>>  drivers/power/supply/ingenic-battery.c | 182 
>> +++++++++++++++++++++++++
>>  3 files changed, 194 insertions(+)
>>  create mode 100644 drivers/power/supply/ingenic-battery.c
>> 
>> diff --git a/drivers/power/supply/Kconfig 
>> b/drivers/power/supply/Kconfig
>> index e901b9879e7e..9bfb1637ec28 100644
>> --- a/drivers/power/supply/Kconfig
>> +++ b/drivers/power/supply/Kconfig
>> @@ -169,6 +169,17 @@ config BATTERY_COLLIE
>>  	  Say Y to enable support for the battery on the Sharp Zaurus
>>  	  SL-5500 (collie) models.
>> 
>> +config BATTERY_INGENIC
>> +	tristate "Ingenic JZ47xx SoCs battery driver"
>> +	depends on MIPS || COMPILE_TEST
>> +	depends on INGENIC_ADC
>> +	help
>> +	  Choose this option if you want to monitor battery status on
>> +	  Ingenic JZ47xx SoC based devices.
>> +
>> +	  This driver can also be built as a module. If so, the module will 
>> be
>> +	  called ingenic-battery.
>> +
>>  config BATTERY_IPAQ_MICRO
>>  	tristate "iPAQ Atmel Micro ASIC battery driver"
>>  	depends on MFD_IPAQ_MICRO
>> diff --git a/drivers/power/supply/Makefile 
>> b/drivers/power/supply/Makefile
>> index b731c2a9b695..9e2c481d0187 100644
>> --- a/drivers/power/supply/Makefile
>> +++ b/drivers/power/supply/Makefile
>> @@ -34,6 +34,7 @@ obj-$(CONFIG_BATTERY_PMU)	+= pmu_battery.o
>>  obj-$(CONFIG_BATTERY_OLPC)	+= olpc_battery.o
>>  obj-$(CONFIG_BATTERY_TOSA)	+= tosa_battery.o
>>  obj-$(CONFIG_BATTERY_COLLIE)	+= collie_battery.o
>> +obj-$(CONFIG_BATTERY_INGENIC)	+= ingenic-battery.o
>>  obj-$(CONFIG_BATTERY_IPAQ_MICRO) += ipaq_micro_battery.o
>>  obj-$(CONFIG_BATTERY_WM97XX)	+= wm97xx_battery.o
>>  obj-$(CONFIG_BATTERY_SBS)	+= sbs-battery.o
>> diff --git a/drivers/power/supply/ingenic-battery.c 
>> b/drivers/power/supply/ingenic-battery.c
>> new file mode 100644
>> index 000000000000..4ee75c1ac241
>> --- /dev/null
>> +++ b/drivers/power/supply/ingenic-battery.c
>> @@ -0,0 +1,182 @@
>> +// SPDX-License-Identifier: GPL-2.0
>> +/*
>> + * Battery driver for the Ingenic JZ47xx SoCs
>> + * Copyright (c) 2019 Artur Rojek <contact@...ur-rojek.eu>
>> + *
>> + * based on drivers/power/supply/jz4740-battery.c
> 
> What is the relationship between this driver and the older one?
This driver intends to replace the older one.

Artur
> 
>> + */
>> +
>> +#include <linux/iio/consumer.h>
>> +#include <linux/module.h>
>> +#include <linux/of.h>
>> +#include <linux/platform_device.h>
>> +#include <linux/power_supply.h>
>> +#include <linux/property.h>
>> +
>> +struct ingenic_battery {
>> +	struct device *dev;
>> +	struct iio_channel *channel;
>> +	struct power_supply_desc desc;
>> +	struct power_supply *battery;
>> +	struct power_supply_battery_info info;
>> +};
>> +
>> +static int ingenic_battery_get_property(struct power_supply *psy,
>> +					enum power_supply_property psp,
>> +					union power_supply_propval *val)
>> +{
>> +	struct ingenic_battery *bat = power_supply_get_drvdata(psy);
>> +	struct power_supply_battery_info *info = &bat->info;
>> +	int ret = 0;
>> +
>> +	switch (psp) {
>> +	case POWER_SUPPLY_PROP_HEALTH:
>> +		ret = iio_read_channel_processed(bat->channel, &val->intval);
>> +		val->intval *= 1000;
>> +		if (val->intval < info->voltage_min_design_uv)
>> +			val->intval = POWER_SUPPLY_HEALTH_DEAD;
>> +		else if (val->intval > info->voltage_max_design_uv)
>> +			val->intval = POWER_SUPPLY_HEALTH_OVERVOLTAGE;
>> +		else
>> +			val->intval = POWER_SUPPLY_HEALTH_GOOD;
>> +	break;
>> +	case POWER_SUPPLY_PROP_VOLTAGE_NOW:
>> +		ret = iio_read_channel_processed(bat->channel, &val->intval);
>> +		val->intval *= 1000;
>> +	break;
>> +	case POWER_SUPPLY_PROP_VOLTAGE_MIN_DESIGN:
>> +		val->intval = info->voltage_min_design_uv;
>> +	break;
>> +	case POWER_SUPPLY_PROP_VOLTAGE_MAX_DESIGN:
>> +		val->intval = info->voltage_max_design_uv;
>> +	break;
>> +	default:
>> +		return -EINVAL;
>> +	};
>> +
> Can't get here, so drop.
> 
>> +	return ret;
>> +}
>> +
>> +/* Set the most appropriate IIO channel voltage reference scale
>> + * based on the battery's max voltage.
>> + */
>> +static int ingenic_battery_set_scale(struct ingenic_battery *bat)
>> +{
>> +	const int *scale_raw;
>> +	int scale_len, scale_type, best_idx = -1, best_mV, max_raw, i, ret;
>> +	u64 max_mV;
>> +
>> +	ret = iio_read_max_channel_raw(bat->channel, &max_raw);
>> +	if (ret) {
>> +		dev_err(bat->dev, "Unable to read max raw channel value\n");
>> +		return ret;
>> +	}
>> +
>> +	ret = iio_read_avail_channel_attribute(bat->channel, &scale_raw,
>> +					       &scale_type, &scale_len,
>> +					       IIO_CHAN_INFO_SCALE);
>> +	if (ret < 0) {
>> +		dev_err(bat->dev, "Unable to read channel avail scale\n");
>> +		return ret;
>> +	}
> This works under the constraints of knowing what ADC we are talking to, 
> but
> this isn't generic.  The relationship between scale and the range isn't 
> always
> direct.  i.e. there are devices where you sample the same range at a 
> lower
> scale to be able to read it faster (can be thought of as oversampling, 
> or
> just not running the last stages of a pipelined ADC).
> Anyhow, doesn't matter here as I assume this is fine on this part.
> 
>> +	if (ret != IIO_AVAIL_LIST || scale_type != IIO_VAL_FRACTIONAL_LOG2)
>> +		return -EINVAL;
>> +
>> +	max_mV = bat->info.voltage_max_design_uv / 1000;
>> +
>> +	for (i = 1; i < scale_len; i += 2) {
>> +		u64 scale_mV = (max_raw * scale_raw[i - 1]) >> scale_raw[i];
> Not keen on the offset in the index being backwards.
> 
> This would be clearer I think as
> 
> for (i = 0; i < scale_len; i+= 2) {
> 	u64 scale_mv = (max_raw * scale_raw[i]) >> scale_raw[i + 1];
> 	...
> 	best_idx = i;
> }
> 
>> +
>> +		if (scale_mV < max_mV)
>> +			continue;
>> +
>> +		if (best_idx >= 0 && scale_mV > best_mV)
>> +			continue;
>> +
>> +		best_mV = scale_mV;
>> +		best_idx = i - 1;
>> +	}
>> +
>> +	if (best_idx < 0) {
>> +		dev_err(bat->dev, "Unable to find matching voltage scale\n");
>> +		return -EINVAL;
>> +	}
>> +
>> +	return iio_write_channel_attribute(bat->channel,
>> +					   scale_raw[best_idx],
>> +					   scale_raw[best_idx+1],
> 
> Spacing around that +.
> 
>> +					   IIO_CHAN_INFO_SCALE);
>> +}
>> +
>> +static enum power_supply_property ingenic_battery_properties[] = {
>> +	POWER_SUPPLY_PROP_HEALTH,
>> +	POWER_SUPPLY_PROP_VOLTAGE_NOW,
>> +	POWER_SUPPLY_PROP_VOLTAGE_MIN_DESIGN,
>> +	POWER_SUPPLY_PROP_VOLTAGE_MAX_DESIGN,
>> +};
>> +
>> +static int ingenic_battery_probe(struct platform_device *pdev)
>> +{
>> +	struct device *dev = &pdev->dev;
>> +	struct ingenic_battery *bat;
>> +	struct power_supply_config psy_cfg = {};
>> +	struct power_supply_desc *desc;
>> +	int ret;
>> +
>> +	bat = devm_kzalloc(dev, sizeof(*bat), GFP_KERNEL);
>> +	if (!bat)
>> +		return -ENOMEM;
>> +
>> +	bat->dev = dev;
>> +	bat->channel = devm_iio_channel_get(dev, "battery");
>> +	if (IS_ERR(bat->channel))
>> +		return PTR_ERR(bat->channel);
>> +
>> +	desc = &bat->desc;
>> +	desc->name = "jz-battery";
>> +	desc->type = POWER_SUPPLY_TYPE_BATTERY;
>> +	desc->properties = ingenic_battery_properties;
>> +	desc->num_properties = ARRAY_SIZE(ingenic_battery_properties);
>> +	desc->get_property = ingenic_battery_get_property;
>> +	psy_cfg.drv_data = bat;
>> +	psy_cfg.of_node = dev->of_node;
>> +
>> +	bat->battery = devm_power_supply_register(dev, desc, &psy_cfg);
>> +	if (IS_ERR(bat->battery)) {
>> +		dev_err(dev, "Unable to register battery\n");
>> +		return PTR_ERR(bat->battery);
>> +	}
>> +
>> +	ret = power_supply_get_battery_info(bat->battery, &bat->info);
>> +	if (ret) {
>> +		dev_err(dev, "Unable to get battery info: %d\n", ret);
>> +		return ret;
>> +	}
>> +	if (bat->info.voltage_min_design_uv < 0) {
>> +		dev_err(dev, "Unable to get voltage min design\n");
>> +		return bat->info.voltage_min_design_uv;
>> +	}
>> +	if (bat->info.voltage_max_design_uv < 0) {
>> +		dev_err(dev, "Unable to get voltage max design\n");
>> +		return bat->info.voltage_max_design_uv;
>> +	}
>> +
>> +	return ingenic_battery_set_scale(bat);
>> +}
>> +
>> +#ifdef CONFIG_OF
>> +static const struct of_device_id ingenic_battery_of_match[] = {
>> +	{ .compatible = "ingenic,jz4740-battery", },
>> +	{ },
>> +};
>> +MODULE_DEVICE_TABLE(of, ingenic_battery_of_match);
>> +#endif
>> +
>> +static struct platform_driver ingenic_battery_driver = {
>> +	.driver = {
>> +		.name = "ingenic-battery",
>> +		.of_match_table = of_match_ptr(ingenic_battery_of_match),
>> +	},
>> +	.probe = ingenic_battery_probe,
>> +};
>> +module_platform_driver(ingenic_battery_driver);

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