Re: [PATCH v5 4/5] hwmon: (adt7475) Add attenuator bypass support

[Guenter Roeck <linux@roeck-us.net>]

On Thu, Feb 27, 2020 at 09:46:41PM +1300, Chris Packham wrote:
> From: Logan Shaw <logan.shaw@alliedtelesis.co.nz>
> 
> Added support for reading DTS properties to set attenuators on
> device probe for the ADT7473, ADT7475, ADT7476, and ADT7490.
> 
> Signed-off-by: Logan Shaw <logan.shaw@alliedtelesis.co.nz>
> Signed-off-by: Chris Packham <chris.packham@alliedtelesis.co.nz>

Applied, with two small changes; see inline.

Thanks,
Guenter

> ---
> 
> Notes:
>     Changes in v5:
>     - None
>     
>     Changes in v4:
>     - use vendor prefix for new property
>     
>     Changes in v3:
>     - move config2 to struct adt7475_data
>     - set_property_bit() new helper function to set/clear bit based on dt
>       property value.
>     - rename to use load_attenuators()
> 
>  drivers/hwmon/adt7475.c | 61 +++++++++++++++++++++++++++++++++++++++--
>  1 file changed, 58 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/hwmon/adt7475.c b/drivers/hwmon/adt7475.c
> index 01c2eeb02aa9..3649b18359dc 100644
> --- a/drivers/hwmon/adt7475.c
> +++ b/drivers/hwmon/adt7475.c
> @@ -19,6 +19,7 @@
>  #include <linux/hwmon-vid.h>
>  #include <linux/err.h>
>  #include <linux/jiffies.h>
> +#include <linux/of.h>
>  #include <linux/util_macros.h>
>  
>  /* Indexes for the sysfs hooks */
> @@ -193,6 +194,7 @@ struct adt7475_data {
>  	unsigned long measure_updated;
>  	bool valid;
>  
> +	u8 config2;
>  	u8 config4;
>  	u8 config5;
>  	u8 has_voltage;
> @@ -1458,6 +1460,55 @@ static int adt7475_update_limits(struct i2c_client *client)
>  	return 0;
>  }
>  
> +static int set_property_bit(const struct i2c_client *client, char *property,
> +			  u8 *config, u8 bit_index)

Aligned continuation line with '('.

> +{
> +	u32 prop_value = 0;
> +	int ret = of_property_read_u32(client->dev.of_node, property,
> +					&prop_value);
> +
> +	if (!ret) {
> +		if (prop_value)
> +			*config |= (1 << bit_index);
> +		else
> +			*config &= ~(1 << bit_index);
> +	}
> +
> +	return ret;
> +}
> +
> +static int load_attenuators(const struct i2c_client *client, int chip,
> +			    struct adt7475_data *data)
> +{
> +	int ret;
> +
> +	if (chip == adt7476 || chip == adt7490) {
> +		set_property_bit(client, "adi,bypass-attenuator-in0",
> +				 &data->config4, 4);
> +		set_property_bit(client, "adi,bypass-attenuator-in1",
> +				 &data->config4, 5);
> +		set_property_bit(client, "adi,bypass-attenuator-in3",
> +				 &data->config4, 6);
> +		set_property_bit(client, "adi,bypass-attenuator-in4",
> +				 &data->config4, 7);
> +
> +		ret = i2c_smbus_write_byte_data(client, REG_CONFIG4,
> +						data->config4);
> +		if (ret < 0)
> +			return ret;
> +	} else if (chip == adt7473 || chip == adt7475) {
> +		set_property_bit(client, "adi,bypass-attenuator-in1",
> +				 &data->config2, 5);
> +
> +		ret = i2c_smbus_write_byte_data(client, REG_CONFIG2,
> +						data->config2);
> +		if (ret < 0)
> +			return ret;
> +	}
> +
> +	return 0;
> +}
> +
>  static int adt7475_probe(struct i2c_client *client,
>  			 const struct i2c_device_id *id)
>  {
> @@ -1472,7 +1523,7 @@ static int adt7475_probe(struct i2c_client *client,
>  	struct adt7475_data *data;
>  	struct device *hwmon_dev;
>  	int i, ret = 0, revision, group_num = 0;
> -	u8 config2, config3;
> +	u8 config3;
>  
>  	data = devm_kzalloc(&client->dev, sizeof(*data), GFP_KERNEL);
>  	if (data == NULL)
> @@ -1546,8 +1597,12 @@ static int adt7475_probe(struct i2c_client *client,
>  	}
>  
>  	/* Voltage attenuators can be bypassed, globally or individually */
> -	config2 = adt7475_read(REG_CONFIG2);
> -	if (config2 & CONFIG2_ATTN) {
> +	data->config2 = adt7475_read(REG_CONFIG2);
> +	ret = load_attenuators(client, chip, data);
> +	if (ret)
> +		dev_err(&client->dev, "Error configuring attenuator bypass\n");

I would expect this to be a dev_warn() or to abort and return an error.
Assuming you want the code to continue in this case, I changed the message
to dev_warn(). If that is not what you want, please let me know.

> +
> +	if (data->config2 & CONFIG2_ATTN) {
>  		data->bypass_attn = (0x3 << 3) | 0x3;
>  	} else {
>  		data->bypass_attn = ((data->config4 & CONFIG4_ATTN_IN10) >> 4) |