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Date: Mon, 12 Feb 2024 01:14:50 +0100
From: Sebastian Reichel <sebastian.reichel@collabora.com>
To: Bhavin Sharma <bhavin.sharma@siliconsignals.io>
Cc: robh+dt@kernel.org, krzysztof.kozlowski+dt@linaro.org, 
	conor+dt@kernel.org, Hardevsinh Palaniya <hardevsinh.palaniya@siliconsignals.io>, 
	linux-pm@vger.kernel.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v3 1/2] power: supply: Add STC3117 fuel gauge unit driver
Message-ID: <eccj4u6ewr33mlp4xqwx5medeysrjuwof7ntwhm6vypmmkss73@qjbpyw5hj3t7>
References: <20240205051321.4079933-1-bhavin.sharma@siliconsignals.io>
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Hi,

On Mon, Feb 05, 2024 at 10:43:17AM +0530, Bhavin Sharma wrote:
> Adding minimal support for stc3117 fuel gauge driver
> to read battery voltage level

Why only voltage?
It should be easy to support more data exposed by the chip.

> Signed-off-by: Bhavin Sharma <bhavin.sharma@siliconsignals.io>
> ---
> Changelogs :
>=20
> v2 -> v3
> - Resolved kernel test robot build warnings
> - Aligned included header files in alphabetical order
> - Removed unused header files
> - Removed unnecessary blank lines
> - Aligned all the macros in alphabetical order
> - Changed macro LSB_VALUE to VOLTAGE_LSB_VALUE
> - Dropped function prototypes and arranged the code accordingly
> - Used macros instead of static numbers for array declaration
> - Removed redundant code
> - Replaced 'power_supply_register' with 'devm_power_supply_register' and =
'pr_err' with 'dev_err'
> - Removed global variables
>=20
> v1 -> v2
> - No change
> ---
>  drivers/power/supply/Kconfig              |   7 ++
>  drivers/power/supply/Makefile             |   1 +
>  drivers/power/supply/stc3117_fuel_gauge.c | 107 ++++++++++++++++++++++
>  3 files changed, 115 insertions(+)
>  create mode 100644 drivers/power/supply/stc3117_fuel_gauge.c
>=20
> diff --git a/drivers/power/supply/Kconfig b/drivers/power/supply/Kconfig
> index f21cb05815ec..e2e3af4bcd5f 100644
> --- a/drivers/power/supply/Kconfig
> +++ b/drivers/power/supply/Kconfig
> @@ -875,6 +875,13 @@ config FUEL_GAUGE_SC27XX
>  	  Say Y here to enable support for fuel gauge with SC27XX
>  	  PMIC chips.
> =20
> +config FUEL_GAUGE_STC3117
> +        tristate "STMicroelectronics STC3117 fuel gauge driver"
> +        depends on I2C
> +        help
> +          Say Y here to enable support for fuel gauge with STC3117
> +          PMIC chips.
> +
>  config CHARGER_UCS1002
>  	tristate "Microchip UCS1002 USB Port Power Controller"
>  	depends on I2C
> diff --git a/drivers/power/supply/Makefile b/drivers/power/supply/Makefile
> index 58b567278034..be8961661bd1 100644
> --- a/drivers/power/supply/Makefile
> +++ b/drivers/power/supply/Makefile
> @@ -104,6 +104,7 @@ obj-$(CONFIG_CHARGER_CROS_USBPD)	+=3D cros_usbpd-char=
ger.o
>  obj-$(CONFIG_CHARGER_CROS_PCHG)	+=3D cros_peripheral_charger.o
>  obj-$(CONFIG_CHARGER_SC2731)	+=3D sc2731_charger.o
>  obj-$(CONFIG_FUEL_GAUGE_SC27XX)	+=3D sc27xx_fuel_gauge.o
> +obj-$(CONFIG_FUEL_GAUGE_STC3117)        +=3D stc3117_fuel_gauge.o
>  obj-$(CONFIG_CHARGER_UCS1002)	+=3D ucs1002_power.o
>  obj-$(CONFIG_CHARGER_BD99954)	+=3D bd99954-charger.o
>  obj-$(CONFIG_CHARGER_WILCO)	+=3D wilco-charger.o
> diff --git a/drivers/power/supply/stc3117_fuel_gauge.c b/drivers/power/su=
pply/stc3117_fuel_gauge.c
> new file mode 100644
> index 000000000000..29eb00b44e21
> --- /dev/null
> +++ b/drivers/power/supply/stc3117_fuel_gauge.c
> @@ -0,0 +1,107 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * stc3117_fuel_gauge.c - STMicroelectronics STC3117 Fuel Gauge Driver
> + *
> + * Copyright (c) 2024 Silicon Signals Pvt Ltd.
> + * Author:      Bhavin Sharma <bhavin.sharma@siliconsignals.io>
> + *              Hardevsinh Palaniya <hardevsinh.palaniya@siliconsignals.=
com>
> + */
> +
> +#include <linux/i2c.h>
> +#include <linux/power_supply.h>
> +
> +#define VOLTAGE_DATA_SIZE	2		// in bytes
> +#define VOLTAGE_LSB_VALUE	2200		// in micro-volts
> +#define VOLTAGE_REG_ADDR	0x08
> +#define VOLTAGE_REG_ADDR_SIZE	1		// in bytes
> +
> +static int stc3117_get_batt_volt(const struct i2c_client *stc_client)
> +{
> +	int ret, volt =3D 0;
> +	char i2c_tx =3D VOLTAGE_REG_ADDR, i2c_rx[VOLTAGE_DATA_SIZE] =3D {0};
> +
> +	ret =3D i2c_master_send(stc_client, &i2c_tx, VOLTAGE_REG_ADDR_SIZE);
> +	if (ret < 0)
> +		return ret;
> +
> +	ret =3D i2c_master_recv(stc_client, i2c_rx, VOLTAGE_DATA_SIZE);
> +	if (ret < 0)
> +		return ret;
> +
> +	volt =3D (i2c_rx[1] << 8) + i2c_rx[0];
> +	volt *=3D VOLTAGE_LSB_VALUE;
> +
> +	return volt;
> +}

Please use regmap.

> +static int stc3117_get_property(struct power_supply *psy,
> +	enum power_supply_property psp, union power_supply_propval *val)
> +{
> +	struct i2c_client *client =3D to_i2c_client(psy->dev.parent);
> +
> +	switch (psp) {
> +	case POWER_SUPPLY_PROP_VOLTAGE_NOW:
> +		val->intval =3D stc3117_get_batt_volt(client);
> +		break;
> +	default:
> +		return -EINVAL;
> +	}
> +	return 0;
> +}
> +
> +static enum power_supply_property stc3117_battery_props[] =3D {
> +	POWER_SUPPLY_PROP_VOLTAGE_NOW,
> +};
> +
> +static const struct power_supply_desc stc3117_battery_desc =3D {
> +	.name =3D "stc3117-battery",
> +	.type =3D POWER_SUPPLY_TYPE_BATTERY,
> +	.get_property =3D stc3117_get_property,
> +	.properties =3D stc3117_battery_props,
> +	.num_properties =3D ARRAY_SIZE(stc3117_battery_props),
> +};
> +
> +static int stc3117_probe(struct i2c_client *client)
> +{
> +	struct power_supply_config psy_cfg =3D {};
> +	struct device *dev;
> +	struct power_supply *stc_sply;
> +
> +	dev =3D &client->dev;

Just initialize this at declaration time.

> +	psy_cfg.of_node =3D dev->of_node;
> +
> +	stc_sply =3D devm_power_supply_register(dev, &stc3117_battery_desc, &ps=
y_cfg);
> +	if (IS_ERR(stc_sply))
> +		dev_err(dev, "failed to register battery\n");

return dev_err_probe(dev, PTR_ERR(stc_sply), "failed to register battery\n"=
);

> +
> +	return 0;
> +}
> +
> +static const struct i2c_device_id stc3117_id[] =3D {
> +	{"stc3117", 0},
> +	{},
> +};
> +MODULE_DEVICE_TABLE(i2c, stc3117_id);
> +
> +static const struct of_device_id stc3117_of_match[] =3D {
> +	{ .compatible =3D "st,stc3117" },
> +	{},
> +};
> +MODULE_DEVICE_TABLE(of, stc3117_of_match);
> +
> +static struct i2c_driver stc3117_i2c_driver =3D {
> +	.driver =3D {
> +		.name =3D "stc3117_i2c_driver",
> +		.of_match_table =3D stc3117_of_match,
> +	},
> +	.probe =3D stc3117_probe,
> +	.id_table =3D stc3117_id,
> +};
> +
> +module_i2c_driver(stc3117_i2c_driver);
> +
> +MODULE_LICENSE("GPL");
> +MODULE_AUTHOR("Bhavin Sharma <bhavin.sharma@siliconsignals.io>");
> +MODULE_AUTHOR("Hardevsinh Palaniya <hardevsinh.palaniya@siliconsignals.i=
o>");
> +MODULE_DESCRIPTION("STC3117 Fuel Gauge Driver");

Greetings,

-- Sebastian

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