Date:   Sun, 24 Mar 2019 15:31:37 +0000
From:   Jonathan Cameron <jic23@...nel.org>
To:     Artur Rojek <contact@...ur-rojek.eu>
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 v2 4/4] power: supply: add Ingenic JZ47xx battery
 driver.

On Sat, 23 Mar 2019 18:28:09 +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>
The IIO parts look fine to me.
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@...wei.com>

Sebastian, assuming you are happy with this version, do you have any
preference for how we handle this series?

Probably needs one of us to do an immutable branch with just this
in it.  I'm happy to do so once all the relevant Acks etc are in
place, but don't mind if you want to!

Thanks,

Jonathan

> ---
> 
> Changes:
> 
> v2: - rework the return logic in ingenic_battery_get_property,
>     - make index offsets point forward in ingenic_battery_set_scale,
>     - fix spacing around scale_raw[best_idx + 1]
> 
>  drivers/power/supply/Kconfig           |  11 ++
>  drivers/power/supply/Makefile          |   1 +
>  drivers/power/supply/ingenic-battery.c | 180 +++++++++++++++++++++++++
>  3 files changed, 192 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..822aee1c7b64
> --- /dev/null
> +++ b/drivers/power/supply/ingenic-battery.c
> @@ -0,0 +1,180 @@
> +// 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
> + */
> +
> +#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;
> +
> +	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;
> +		return ret;
> +	case POWER_SUPPLY_PROP_VOLTAGE_NOW:
> +		ret = iio_read_channel_processed(bat->channel, &val->intval);
> +		val->intval *= 1000;
> +		return ret;
> +	case POWER_SUPPLY_PROP_VOLTAGE_MIN_DESIGN:
> +		val->intval = info->voltage_min_design_uv;
> +		return 0;
> +	case POWER_SUPPLY_PROP_VOLTAGE_MAX_DESIGN:
> +		val->intval = info->voltage_max_design_uv;
> +		return 0;
> +	default:
> +		return -EINVAL;
> +	};
> +}
> +
> +/* 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;
> +	}
> +	if (ret != IIO_AVAIL_LIST || scale_type != IIO_VAL_FRACTIONAL_LOG2)
> +		return -EINVAL;
> +
> +	max_mV = bat->info.voltage_max_design_uv / 1000;
> +
> +	for (i = 0; i < scale_len; i += 2) {
> +		u64 scale_mV = (max_raw * scale_raw[i]) >> scale_raw[i + 1];
> +
> +		if (scale_mV < max_mV)
> +			continue;
> +
> +		if (best_idx >= 0 && scale_mV > best_mV)
> +			continue;
> +
> +		best_mV = scale_mV;
> +		best_idx = i;
> +	}
> +
> +	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],
> +					   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),

I guess we can be fairly sure no one will even user this with ACPI
(magic DT) bindings?  That would make this a rare case where the
of_match_pr protection and ifdef fun is still fine.


> +	},
> +	.probe = ingenic_battery_probe,
> +};
> +module_platform_driver(ingenic_battery_driver);

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