RE: [PATCH v4 4/4] hwmon: (pmbus/max20830): add support for max20830c and max20840c

[Torreno, Alexis Czezar]

> 
> [External]
> 
> On 7/27/26 20:32, Alexis Czezar Torreno wrote:
> > Add support for MAX20830C and MAX20840 step-down DC-DC switching
> > regulator with PMBus interface. MAX20830C is a different packaging for
> > MAX20830, and MAX20840C supports 40A regulation compared to
> > MAX20830 that is only 30A.
> >
> 
> Are those chips still not published ? I find MAX20840T, but no "C" variants.
> And MAX20840T presumably has an I2C device ID of "MAX20840", not
> "MAX20840C".
> 
> I also noticed that MAX20810 and MAX20815 seem to be register compatible.
> 

I believe so yes, they aren't yet.

Actually MAX20810/815 and a few more are next in line after this. A different
person is handling it, but they're waiting on how this patches go.

> > Signed-off-by: Alexis Czezar Torreno <alexisczezar.torreno@xxxxxxxxxx>
> > ---
> >   Documentation/hwmon/max20830.rst | 27 ++++++++++++++++++++++-----
> >   drivers/hwmon/pmbus/max20830.c   | 27 ++++++++++++++-------------
> >   2 files changed, 36 insertions(+), 18 deletions(-)
> >
> > diff --git a/Documentation/hwmon/max20830.rst
> > b/Documentation/hwmon/max20830.rst
> > index
> >
> 936e409dcc5c0898dde27d782308d4a7e1357e73..b850f3b6e40d1f1d0cec944be
> 40a
> > f02265aced59 100644
> > --- a/Documentation/hwmon/max20830.rst
> > +++ b/Documentation/hwmon/max20830.rst
> > @@ -13,6 +13,22 @@ Supported chips:
> >
> >       Datasheet:
> > https://www.analog.com/media/en/technical-documentation/data-sheets/ma
> > x20830.pdf
> >
> > +  * Analog Devices MAX20830C
> > +
> > +    Prefix: 'max20830c'
> > +
> > +    Addresses scanned: -
> > +
> > +    Datasheet:
> > +
> > +  * Analog Devices MAX20840C
> > +
> > +    Prefix: 'max20840c'
> > +
> > +    Addresses scanned: -
> > +
> > +    Datasheet:
> > +
> >   Author:
> >
> >     - Alexis Czezar Torreno <alexisczezar.torreno@xxxxxxxxxx> @@
> > -21,12 +37,13 @@ Author:
> >   Description
> >   -----------
> >
> > -This driver supports hardware monitoring for Analog Devices MAX20830
> > -Step-Down Switching Regulator with PMBus Interface.
> > +This driver supports hardware monitoring for Analog Devices MAX20830,
> > +MAX20830C and MAX20840C. These are Step-Down Switching Regulator
> with PMBus Interface.
> >
> > -The MAX20830 is a 2.7V to 16V, 30A fully integrated step-down DC-DC
> > switching -regulator. Through the PMBus interface, the device can
> > monitor input/output -voltages, output current and temperature.
> > +MAX20830, and MAX20830C are 2.7V to 16V, 30A fully integrated
> > +step-down DC-DC switching regulators. MAX20840C is similar but can
> > +reach 40A. Through the PMBus interface, these devices can monitor
> > +input/output voltages, output current and temperature.
> >
> >   The driver is a client driver to the core PMBus driver. Please see
> >   Documentation/hwmon/pmbus.rst for details on PMBus client drivers.
> > diff --git a/drivers/hwmon/pmbus/max20830.c
> > b/drivers/hwmon/pmbus/max20830.c index
> >
> 7c1e94c43ac4e5d1b4f69dc77b02e424a674e908..029733a377123ae6a861841d
> b4a4
> > 0dd540f1149e 100644
> > --- a/drivers/hwmon/pmbus/max20830.c
> > +++ b/drivers/hwmon/pmbus/max20830.c
> > @@ -99,13 +99,12 @@ static int max20830_probe(struct i2c_client *client)
> >   	 * which do not support SMBus block reads.
> >   	 */
> >   	if (i2c_check_functionality(client->adapter,
> I2C_FUNC_SMBUS_READ_BLOCK_DATA)) {
> > -		/* Reads 9 Data bytes from MAX20830 */
> >   		ret = i2c_smbus_read_block_data(client,
> PMBUS_IC_DEVICE_ID, buf);
> >   		if (ret < 0)
> >   			return dev_err_probe(&client->dev, ret,
> >   					     "Failed to read IC_DEVICE_ID\n");
> >   	} else {
> > -		/* Reads 1 length byte + 9 Data bytes from MAX20830 */
> > +		/* Reads 1 length byte + data bytes */
> >   		ret = i2c_smbus_read_i2c_block_data(client,
> PMBUS_IC_DEVICE_ID,
> >
> MAX20830_IC_DEVICE_ID_LENGTH + 1,
> >   						    buf);
> > @@ -121,26 +120,28 @@ static int max20830_probe(struct i2c_client
> *client)
> >   		ret = ret - 1;
> >   	}
> >
> > -	/*
> > -	 * MAX20830 IC_DEVICE_ID sends string data "MAX20830\0".
> > -	 * Return value should at least be 9 bytes of data.
> > -	 */
> > +	/* Verify we read the expected number of bytes */
> >   	if (ret < MAX20830_IC_DEVICE_ID_LENGTH)
> >   		return dev_err_probe(&client->dev, -ENODEV,
> > -				     "IC_DEVICE_ID too short: expected at least
> 9 bytes, got %d\n",
> > -				     ret);
> > +				     "IC_DEVICE_ID too short: expected %d
> bytes, got %d\n",
> > +				     MAX20830_IC_DEVICE_ID_LENGTH, ret);
> > +
> > +	/* Null-terminate the string */
> > +	buf[ret] = '\0';
> >
> > -	/* 9 bytes of data, buf[0]-buf[7] = "MAX20830", buf[8] = '\0' */
> > -	buf[MAX20830_IC_DEVICE_ID_LENGTH - 1] = '\0';
> > -	if (strncmp(buf, "MAX20830", MAX20830_IC_DEVICE_ID_LENGTH - 1))
> > +	/* Verify the device ID matches what we expect */
> > +	if ((strcmp(buf, "MAX20830") && strcmp(buf, "MAX20830C") &&
> > +	    strcmp(buf, "MAX20840C")))
> >   		return dev_err_probe(&client->dev, -ENODEV,
> > -				     "Unsupported device: '%s'\n", buf);
> > +				     "Unsupported device: '%*pE'\n", ret, buf);
> >
> >   	return pmbus_do_probe(client, &data->info);
> >   }
> >
> >   static const struct i2c_device_id max20830_id[] = {
> > -	{"max20830"},
> > +	{ "max20830" },
> > +	{ "max20830c" },
> > +	{ "max20840c" },
> 
> I don't think that is needed or warranted, given that there is no matching
> devicetree node.
> 

I see, will remove.