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

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On 18/03/22 02:28, Guenter Roeck wrote:
> 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@xxxxxxxxxxxxxxxxxxx>
>> ---
>>   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.

Yep that'd be a better name.

>
>> +    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).

Ikegami-san and Dan did to some good work to address some of that. The 
probe function is still quite careless.

I'll see what I can do to make sure my additions don't make it worse.
>
>> +
>> +        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.
>
Have you got a better suggestion? I was trying to avoid someone 
specifying compatible = "adi,adt7476" with "adi,pin5-function". Is your 
concern that I should use -ENODEV or that I should just pick more 
generic names for the configurable pins (naming things is hard).

Or perhaps just dev_warn() and return 0?

>> +    }
>> +
>> +    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.
>
Sorry that is old. I initially was under the impression that only these 
2 had configurable pins but then I read the other datasheets more closely.
>> +    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.
>
Now I've got the prop names I can use that instead.
>> +        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))
>




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