Re: [PATCH 2/2] power: supply: ltc2941-battery-gauge: Add support for LTC2942

[Mike Looijmans <mike.looijmans@topic.nl>]

On 12-6-2017 17:04, Ladislav Michl wrote:
> LTC2942 is pin compatible with LTC2941 providing additional
> informations about battery voltage and temperature. It can
> be runtime detected using bit A7 in the Status register.

Runtime detection is always nice. I'd suggest adding "ltc2942" to the 
device name list, since having to specify "ltc2941" when the chip is in 
fact an "ltc2942" looks a bit strange.

Again, no strong preference, whatever the maintainers think is best is 
fine with me also.

>
> Signed-off-by: Ladislav Michl <ladis@linux-mips.org>
> ---
>  drivers/power/supply/ltc2941-battery-gauge.c | 56 ++++++++++++++++++++--------
>  1 file changed, 41 insertions(+), 15 deletions(-)
>
> diff --git a/drivers/power/supply/ltc2941-battery-gauge.c b/drivers/power/supply/ltc2941-battery-gauge.c
> index 0a1b69bbca7f..07e47478dbc6 100644
> --- a/drivers/power/supply/ltc2941-battery-gauge.c
> +++ b/drivers/power/supply/ltc2941-battery-gauge.c
> @@ -44,6 +44,8 @@ enum ltc294x_reg {
>  	LTC2943_REG_TEMPERATURE_LSB	= 0x15,
>  };
>
> +#define LTC2941_REG_STATUS_CHIP_ID	BIT(7)
> +
>  #define LTC2943_REG_CONTROL_MODE_MASK (BIT(7) | BIT(6))
>  #define LTC2943_REG_CONTROL_MODE_SCAN BIT(7)
>  #define LTC294X_REG_CONTROL_PRESCALER_MASK	(BIT(5) | BIT(4) | BIT(3))
> @@ -250,8 +252,9 @@ static int ltc294x_get_voltage(const struct ltc294x_info *info, int *val)
>
>  	ret = ltc294x_read_regs(info->client,
>  		LTC294X_REG_VOLTAGE_MSB, &datar[0], 2);
> -	value = (datar[0] << 8) | datar[1];
> -	*val = ((value * 23600) / 0xFFFF) * 1000; /* in uV */
> +	value = info->num_regs == LTC2943_NUM_REGS ? 23600 : 6000;
> +	value *= (datar[0] << 8) | datar[1];
> +	*val = 1000 * value / 0xFFFF; /* in uV */
>  	return ret;
>  }
>
> @@ -274,15 +277,22 @@ static int ltc294x_get_current(const struct ltc294x_info *info, int *val)
>
>  static int ltc294x_get_temperature(const struct ltc294x_info *info, int *val)
>  {
> +	enum ltc294x_reg reg;
>  	int ret;
>  	u8 datar[2];
>  	u32 value;
>
> -	ret = ltc294x_read_regs(info->client,
> -		LTC2943_REG_TEMPERATURE_MSB, &datar[0], 2);
> -	value = (datar[0] << 8) | datar[1];
> -	/* Full-scale is 510 Kelvin, convert to centidegrees  */
> -	*val = (((51000 * value) / 0xFFFF) - 27215);
> +	if (info->num_regs == LTC2943_NUM_REGS) {
> +		reg = LTC2943_REG_TEMPERATURE_MSB;
> +		value = 51000;	/* Full-scale is 510 Kelvin */
> +	} else {
> +		reg = LTC2942_REG_TEMPERATURE_MSB;
> +		value = 60000;	/* Full-scale is 600 Kelvin */
> +	}
> +	ret = ltc294x_read_regs(info->client, reg, &datar[0], 2);
> +	value *= (datar[0] << 8) | datar[1];
> +	/* Convert to centidegrees  */
> +	*val = value / 0xFFFF - 27215;
>  	return ret;
>  }
>
> @@ -356,8 +366,8 @@ static enum power_supply_property ltc294x_properties[] = {
>  	POWER_SUPPLY_PROP_CHARGE_COUNTER,
>  	POWER_SUPPLY_PROP_CHARGE_NOW,
>  	POWER_SUPPLY_PROP_VOLTAGE_NOW,
> -	POWER_SUPPLY_PROP_CURRENT_NOW,
>  	POWER_SUPPLY_PROP_TEMP,
> +	POWER_SUPPLY_PROP_CURRENT_NOW,
>  };
>
>  static int ltc294x_i2c_remove(struct i2c_client *client)
> @@ -374,10 +384,11 @@ static int ltc294x_i2c_probe(struct i2c_client *client,
>  {
>  	struct power_supply_config psy_cfg = {};
>  	struct ltc294x_info *info;
> +	struct device_node *np;
>  	int ret;
>  	u32 prescaler_exp;
>  	s32 r_sense;
> -	struct device_node *np;
> +	u8 status;
>
>  	info = devm_kzalloc(&client->dev, sizeof(*info), GFP_KERNEL);
>  	if (info == NULL)
> @@ -420,21 +431,36 @@ static int ltc294x_i2c_probe(struct i2c_client *client,
>  				(128 / (1 << prescaler_exp));
>  	}
>
> +	/* Read status register to check for LTC2942 */
> +	if (info->num_regs == LTC2941_NUM_REGS) {
> +		ret = ltc294x_read_regs(client, LTC294X_REG_STATUS, &status, 1);
> +		if (ret < 0) {
> +			dev_err(&info->client->dev,
> +				"Could not read status register\n");
> +			return ret;
> +		}
> +		if (!(status & LTC2941_REG_STATUS_CHIP_ID))
> +			info->num_regs = LTC2942_NUM_REGS;
> +	}
> +
>  	info->client = client;
>  	info->supply_desc.type = POWER_SUPPLY_TYPE_BATTERY;
>  	info->supply_desc.properties = ltc294x_properties;
> -	if (info->num_regs >= LTC2943_REG_TEMPERATURE_LSB)
> +	switch (info->num_regs) {
> +	case LTC2943_NUM_REGS:
>  		info->supply_desc.num_properties =
>  			ARRAY_SIZE(ltc294x_properties);
> -	else if (info->num_regs >= LTC2943_REG_CURRENT_LSB)
> +		break;
> +	case LTC2942_NUM_REGS:
>  		info->supply_desc.num_properties =
>  			ARRAY_SIZE(ltc294x_properties) - 1;
> -	else if (info->num_regs >= LTC294X_REG_VOLTAGE_LSB)
> -		info->supply_desc.num_properties =
> -			ARRAY_SIZE(ltc294x_properties) - 2;
> -	else
> +		break;
> +	case LTC2941_NUM_REGS:
> +	default:
>  		info->supply_desc.num_properties =
>  			ARRAY_SIZE(ltc294x_properties) - 3;
> +		break;
> +	}
>  	info->supply_desc.get_property = ltc294x_get_property;
>  	info->supply_desc.set_property = ltc294x_set_property;
>  	info->supply_desc.property_is_writeable = ltc294x_property_is_writeable;
>


-- 
Mike Looijmans


Kind regards,

Mike Looijmans
System Expert

TOPIC Products
Materiaalweg 4, NL-5681 RJ Best
Postbus 440, NL-5680 AK Best
Telefoon: +31 (0) 499 33 69 79
E-mail: mike.looijmans@topicproducts.com
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