Re: [PATCH v3 4/5] hwmon: pmbus: mpq8785: Add support for MPM82504

[Guenter Roeck]

On 5/10/25 02:18, 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@xxxxxxxxx>
>
> ---
> v3:
>    - fix alphabetical order in multiple places
>    - change PMBUS_READ_TEMPERATURE_1_SIGN macro name to
>      MPM82504_READ_TEMPERATURE_1_SIGN
>    - use sign_extend32()
>    - fix typo in documentation
> v2:
>    - fixed signedess for temperatures < 0 deg C
>    - removed empty lines
> ---
>   Documentation/hwmon/mpq8785.rst | 20 +++++++++++++++-----
>   drivers/hwmon/pmbus/mpq8785.c   | 33 ++++++++++++++++++++++++++++++++-
>   2 files changed, 47 insertions(+), 6 deletions(-)
>
> diff --git a/Documentation/hwmon/mpq8785.rst b/Documentation/hwmon/mpq8785.rst
> index bf8176b87086..b91fefb1a84c 100644
> --- a/Documentation/hwmon/mpq8785.rst
> +++ b/Documentation/hwmon/mpq8785.rst
> @@ -5,6 +5,7 @@ Kernel driver mpq8785
>   
>   Supported chips:
>   
> +  * MPS MPM82504
>     * MPS MPQ8785
>   
>       Prefix: 'mpq8785'
> @@ -14,6 +15,14 @@ Author: Charles Hsu <ythsu0511@xxxxxxxxx>
>   Description
>   -----------
>   
> +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 MPQ8785 is a fully integrated, PMBus-compatible, high-frequency, synchronous
>   buck converter. The MPQ8785 offers a very compact solution that achieves up to
>   40A output current per phase, with excellent load and line regulation over a
> @@ -23,18 +32,19 @@ output current 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 channels to be connected in
> +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 MPM82504 is available in a BGA (15mmx30mmx5.18mm)
> +package and the MPQ8785 is available in a TLGA (5mmx6mm) package.
>   
>   Device compliant with:
>   
> diff --git a/drivers/hwmon/pmbus/mpq8785.c b/drivers/hwmon/pmbus/mpq8785.c
> index 2e7c0d0c3f81..1e12e7267a7f 100644
> --- a/drivers/hwmon/pmbus/mpq8785.c
> +++ b/drivers/hwmon/pmbus/mpq8785.c
> @@ -4,14 +4,19 @@
>    */
>   
>   #include <linux/i2c.h>
> +#include <linux/bitops.h>
>   #include <linux/module.h>
>   #include <linux/property.h>
>   #include <linux/of_device.h>
>   #include "pmbus.h"
>   
> -enum chips { mpq8785 };
> +#define MPM82504_READ_TEMPERATURE_1_SIGN	BIT(9)
> +#define MPM82504_READ_TEMPERATURE_1_SIGN_POS	9
> +
> +enum chips { mpm82504, mpq8785 };
>   
>   static u16 voltage_scale_loop_max_val[] = {
> +	[mpm82504] = GENMASK(9, 0),
>   	[mpq8785] = GENMASK(10, 0),
>   };
>   
> @@ -41,6 +46,23 @@ 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 & MPM82504_READ_TEMPERATURE_1_SIGN)

When using sign_extend32() is that the conditional is not needed.

Guenter

> +		ret = sign_extend32(ret, MPM82504_READ_TEMPERATURE_1_SIGN_POS) & 0xffff;
> +
> +	return ret;
> +}
> +
>   static struct pmbus_driver_info mpq8785_info = {
>   	.pages = 1,
>   	.format[PSC_VOLTAGE_IN] = direct,
> @@ -63,12 +85,14 @@ static struct pmbus_driver_info mpq8785_info = {
>   };
>   
>   static const struct i2c_device_id mpq8785_id[] = {
> +	{ "mpm82504", mpm82504 },
>   	{ "mpq8785", mpq8785 },
>   	{ },
>   };
>   MODULE_DEVICE_TABLE(i2c, mpq8785_id);
>   
>   static const struct of_device_id __maybe_unused mpq8785_of_match[] = {
> +	{ .compatible = "mps,mpm82504", .data = (void *)mpm82504 },
>   	{ .compatible = "mps,mpq8785", .data = (void *)mpq8785 },
>   	{}
>   };
> @@ -92,6 +116,13 @@ static int mpq8785_probe(struct i2c_client *client)
>   		chip_id = (kernel_ulong_t)i2c_get_match_data(client);
>   
>   	switch (chip_id) {
> +	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;
>   	case mpq8785:
>   		info->identify = mpq8785_identify;
>   		break;