Re: [PATCH 2/2] hwmon: (adt7475) Add support for pin configuration

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

On 3/16/22 16:41, Chris Packham wrote:
> The adt7473, adt7475, adt7476 and adt7490 have pins that can be used for
> different functions. On the adt7473 and  adt7475 this is pins 5 and 9.
> On the adt7476 and adt7490 this is pins 10 and 14.
> 
> The first pin can either be PWM2(default) or SMBALERT#. The second pin
> can be TACH4(default), THERM#, SMBALERT# or GPIO.
> 
> The adt7475 driver has always been able to detect the configuration if
> it had been done by an earlier boot stage. Add support for configuring
> the pins based on the hardware description in the device tree.
> 
> Signed-off-by: Chris Packham <chris.packham@alliedtelesis.co.nz>
> ---
>   drivers/hwmon/adt7475.c | 95 +++++++++++++++++++++++++++++++++++++++++
>   1 file changed, 95 insertions(+)
> 
> diff --git a/drivers/hwmon/adt7475.c b/drivers/hwmon/adt7475.c
> index 9d5b019651f2..ad5e5a7a844b 100644
> --- a/drivers/hwmon/adt7475.c
> +++ b/drivers/hwmon/adt7475.c
> @@ -112,6 +112,8 @@
>   #define CONFIG3_THERM		0x02
>   
>   #define CONFIG4_PINFUNC		0x03
> +#define CONFIG4_THERM		0x01
> +#define CONFIG4_SMBALERT	0x02
>   #define CONFIG4_MAXDUTY		0x08
>   #define CONFIG4_ATTN_IN10	0x30
>   #define CONFIG4_ATTN_IN43	0xC0
> @@ -1460,6 +1462,95 @@ static int adt7475_update_limits(struct i2c_client *client)
>   	return 0;
>   }
>   
> +static int load_pin10_config(const struct i2c_client *client, const char *propname)
> +{

A better function name would probably be load_config3() or similar.

> +	const char *function;
> +	u8 config3;
> +	int err;
> +
> +	err = of_property_read_string(client->dev.of_node, propname, &function);
> +	if (!err) {
> +		config3 = adt7475_read(REG_CONFIG3);

error check missing (I see the driver is notorious for that, but that is not
a reason to keep doing it).

> +
> +		if (!strcmp("pwm2", function))
> +			config3 &= ~CONFIG3_SMBALERT;
> +		else if (!strcmp("smbalert#", function))
> +			config3 |= CONFIG3_SMBALERT;
> +		else
> +			return -EINVAL;
> +
> +		return i2c_smbus_write_byte_data(client, REG_CONFIG3, config3);
> +	}
> +
> +	return 0;
> +}
> +
> +static int load_pin14_config(const struct i2c_client *client, const char *propname)
> +{

load_config4() ?

> +	const char *function;
> +	u8 config4;
> +	int err;
> +
> +	err = of_property_read_string(client->dev.of_node, propname, &function);
> +	if (!err) {
> +		config4 = adt7475_read(REG_CONFIG4);

error check

> +		config4 &= ~CONFIG4_PINFUNC;
> +
> +		if (!strcmp("tach4", function))
> +			;
> +		else if (!strcmp("therm#", function))
> +			config4 |= CONFIG4_THERM;
> +		else if (!strcmp("smbalert#", function))
> +			config4 |= CONFIG4_SMBALERT;
> +		else if (!strcmp("gpio", function))
> +			config4 |= CONFIG4_PINFUNC;
> +		else
> +			return -EINVAL;
> +
> +		return i2c_smbus_write_byte_data(client, REG_CONFIG4, config4);
> +	}
> +
> +	return 0;
> +}
> +
> +static int load_config(const struct i2c_client *client, int chip)
> +{
> +	int err;
> +	const char *conf_prop1, *conf_prop2;

conf_ prefix is unnecessary.

> +
> +	switch (chip) {
> +	case adt7473:
> +	case adt7475:
> +		conf_prop1 = "adi,pin5-function";
> +		conf_prop2 = "adi,pin9-function";
> +		break;
> +	case adt7476:
> +	case adt7490:
> +		conf_prop1 = "adi,pin10-function";
> +		conf_prop2 = "adi,pin14-function";
> +		break;
> +	default:
> +		return -EINVAL;

It doesn't seem right to return -EINVAL here.

> +	}
> +
> +	if (chip != adt7476 && chip != adt7490)
> +		return 0;
> +

Why not check this first, and what is the point of assigning values to
conf_prop1 and conf_prop2 for the other chips in the case statement above
only to return 0 here ? It would be much simpler to drop the other chips
from the case statement and have default: return 0.

> +	err = load_pin10_config(client, conf_prop1);
> +	if (err) {
> +		dev_err(&client->dev, "failed to configure PIN10\n");

The messages are misleading. This isn't always pin 10/14.

> +		return err;
> +	}
> +
> +	err = load_pin14_config(client, conf_prop2);
> +	if (err) {
> +		dev_err(&client->dev, "failed to configure PIN14\n");
> +		return err;
> +	}
> +
> +	return 0;
> +}
> +
>   static int set_property_bit(const struct i2c_client *client, char *property,
>   			    u8 *config, u8 bit_index)
>   {
> @@ -1585,6 +1676,10 @@ static int adt7475_probe(struct i2c_client *client)
>   		revision = adt7475_read(REG_DEVID2) & 0x07;
>   	}
>   
> +	ret = load_config(client, chip);
> +	if (ret)
> +		return ret;
> +
>   	config3 = adt7475_read(REG_CONFIG3);
>   	/* Pin PWM2 may alternatively be used for ALERT output */
>   	if (!(config3 & CONFIG3_SMBALERT))