Re: [PATCH v2 2/5] hwmon: pmbus: mpq8785: Add support for MPM82504

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

On 5/8/25 23:51, Pawel Dembicki wrote:
> Add support for the Monolithic Power Systems MPM82504 digital voltage
> regulator. MPM82504 uses PMBus direct format for voltage output.
> 
> Tested with device tree based matching.
> 
> Signed-off-by: Pawel Dembicki <paweldembicki@gmail.com>
> 
> ---
> v2:
>    - fixed signedess for temperatures < 0 deg C
>    - remove empty lines
> ---
>   Documentation/hwmon/mpq8785.rst | 20 +++++++++++++++-----
>   drivers/hwmon/pmbus/mpq8785.c   | 30 +++++++++++++++++++++++++++++-
>   2 files changed, 44 insertions(+), 6 deletions(-)
> 
> diff --git a/Documentation/hwmon/mpq8785.rst b/Documentation/hwmon/mpq8785.rst
> index bf8176b87086..be228ee58ce2 100644
> --- a/Documentation/hwmon/mpq8785.rst
> +++ b/Documentation/hwmon/mpq8785.rst
> @@ -6,6 +6,7 @@ Kernel driver mpq8785
>   Supported chips:
>   
>     * MPS MPQ8785
> +  * MPS MPM82504
>   
>       Prefix: 'mpq8785'
>   
> @@ -20,21 +21,30 @@ buck converter. The MPQ8785 offers a very compact solution that achieves up to
>   wide input supply range. The MPQ8785 operates at high efficiency over a wide
>   output current load range.
>   
> +The MPM82504 is a quad 25A, scalable, fully integrated power module with a PMBus
> +interface. The device offers a complete power solution that achieves up to 25A
> +per output channel. The MPM82504 has four output channels that can be paralleled
> +to provide 50A, 75A, or 100A of output current for flexible configurations.
> +The device can also operate in parallel with the MPM3695-100 and additional
> +MPM82504 devices to provide a higher output current. The MPM82504 operates
> +at high efficiency across a wide load range.
> +
>   The PMBus interface provides converter configurations and key parameters
>   monitoring.
>   
> -The MPQ8785 adopts MPS's proprietary multi-phase digital constant-on-time (MCOT)
> +The devices adopts MPS's proprietary multi-phase digital constant-on-time (MCOT)
>   control, which provides fast transient response and eases loop stabilization.
> -The MCOT scheme also allows multiple MPQ8785 devices to be connected in parallel
> -with excellent current sharing and phase interleaving for high-current
> +The MCOT scheme also allows multiple devices or chennels to be connected in

channels

> +parallel with excellent current sharing and phase interleaving for high-current
>   applications.
>   
>   Fully integrated protection features include over-current protection (OCP),
>   over-voltage protection (OVP), under-voltage protection (UVP), and
>   over-temperature protection (OTP).
>   
> -The MPQ8785 requires a minimal number of readily available, standard external
> -components, and is available in a TLGA (5mmx6mm) package.
> +All supported modules require a minimal number of readily available, standard
> +external components. The MPQ8785 is available in a TLGA (5mmx6mm) package
> +and the MPM82504 is available in a BGA (15mmx30mmx5.18mm) package.
>   
>   Device compliant with:
>   
> diff --git a/drivers/hwmon/pmbus/mpq8785.c b/drivers/hwmon/pmbus/mpq8785.c
> index 00ec21b081cb..9a4a211b2aeb 100644
> --- a/drivers/hwmon/pmbus/mpq8785.c
> +++ b/drivers/hwmon/pmbus/mpq8785.c
> @@ -8,7 +8,9 @@
>   #include <linux/of_device.h>
>   #include "pmbus.h"
>   
> -enum chips { mpq8785 };
> +#define PMBUS_READ_TEMPERATURE_1_SIGN	BIT(9)

s/PMBUS/MPM82504/

because this is not a standard bit. Needs to include linux/bits.h
or better linux/bitops.h (see below).

> +
> +enum chips { mpq8785, mpm82504 };

Please keep those in alphabetic order.
>   
>   static int mpq8785_identify(struct i2c_client *client,
>   			    struct pmbus_driver_info *info)
> @@ -36,6 +38,23 @@ static int mpq8785_identify(struct i2c_client *client,
>   	return 0;
>   };
>   
> +static int mpm82504_read_word_data(struct i2c_client *client, int page,
> +				   int phase, int reg)
> +{
> +	int ret;
> +
> +	ret = pmbus_read_word_data(client, page, phase, reg);
> +
> +	if (ret < 0 || reg != PMBUS_READ_TEMPERATURE_1)
> +		return ret;
> +
> +	/* Fix PMBUS_READ_TEMPERATURE_1 signedness */
> +	if (ret & PMBUS_READ_TEMPERATURE_1_SIGN)
> +		ret |= GENMASK(15, 10);

Better use sign_extend32(ret, PMBUS_READ_TEMPERATURE_1_SIGN) & 0xffff.
The mask is a bit odd but there is no sign_extend16(), but this makes it
more obvious what is done here.

Also, this needs to include linux/bitops.h.

> +
> +	return ret;
> +}
> +
>   static struct pmbus_driver_info mpq8785_info = {
>   	.pages = 1,
>   	.format[PSC_VOLTAGE_IN] = direct,
> @@ -59,12 +78,14 @@ static struct pmbus_driver_info mpq8785_info = {
>   
>   static const struct i2c_device_id mpq8785_id[] = {
>   	{ "mpq8785", mpq8785 },
> +	{ "mpm82504", mpm82504 },
>   	{ },
>   };
>   MODULE_DEVICE_TABLE(i2c, mpq8785_id);
>   
>   static const struct of_device_id __maybe_unused mpq8785_of_match[] = {
>   	{ .compatible = "mps,mpq8785", .data = (void *)mpq8785 },
> +	{ .compatible = "mps,mpm82504", .data = (void *)mpm82504 },

Alphabetic order.

>   	{}
>   };
>   MODULE_DEVICE_TABLE(of, mpq8785_of_match);
> @@ -88,6 +109,13 @@ static int mpq8785_probe(struct i2c_client *client)
>   	case mpq8785:
>   		info->identify = mpq8785_identify;
>   		break;
> +	case mpm82504:
> +		info->format[PSC_VOLTAGE_OUT] = direct;
> +		info->m[PSC_VOLTAGE_OUT] = 8;
> +		info->b[PSC_VOLTAGE_OUT] = 0;
> +		info->R[PSC_VOLTAGE_OUT] = 2;
> +		info->read_word_data = mpm82504_read_word_data;
> +		break;

Same here, with case statements. Sorry, I should have noticed in v1.

Thanks,
Guenter

>   	default:
>   		return -ENODEV;
>   	}