Commit 6e9ef8ca authored by Chris Packham's avatar Chris Packham Committed by Guenter Roeck
Browse files

hwmon: (pmbus/bpa-rs600) Handle Vin readings >= 256V 



The BPA-RS600 doesn't follow the PMBus spec for linear data.
Specifically it treats the mantissa as an unsigned 11-bit value instead
of a two's complement 11-bit value. At this point it's unclear whether
this only affects Vin or if Pin/Pout1 are affected as well. Erring on
the side of caution only Vin is dealt with here.

Fixes: 15b2703e ("hwmon: (pmbus) Add driver for BluTek BPA-RS600")
Signed-off-by: default avatarChris Packham <chris.packham@alliedtelesis.co.nz>
Link: https://lore.kernel.org/r/20210616034218.25821-1-chris.packham@alliedtelesis.co.nz


Signed-off-by: default avatarGuenter Roeck <linux@roeck-us.net>
parent 009c9aa5

drivers/hwmon/pmbus/bpa-rs600.c

+29 −0
Original line number Diff line number Diff line
@@ -46,6 +46,32 @@ static int bpa_rs600_read_byte_data(struct i2c_client *client, int page, int reg 
	return ret;

}



/*

 * The BPA-RS600 violates the PMBus spec. Specifically it treats the

 * mantissa as unsigned. Deal with this here to allow the PMBus core

 * to work with correctly encoded data.

 */

static int bpa_rs600_read_vin(struct i2c_client *client)

{

	int ret, exponent, mantissa;



	ret = pmbus_read_word_data(client, 0, 0xff, PMBUS_READ_VIN);

	if (ret < 0)

		return ret;



	if (ret & BIT(10)) {

		exponent = ret >> 11;

		mantissa = ret & 0x7ff;



		exponent++;

		mantissa >>= 1;



		ret = (exponent << 11) | mantissa;

	}



	return ret;

}



static int bpa_rs600_read_word_data(struct i2c_client *client, int page, int phase, int reg)

{

	int ret;
@@ -85,6 +111,9 @@ static int bpa_rs600_read_word_data(struct i2c_client *client, int page, int pha 
		/* These commands return data but it is invalid/un-documented */

		ret = -ENXIO;

		break;

	case PMBUS_READ_VIN:

		ret = bpa_rs600_read_vin(client);

		break;

	default:

		if (reg >= PMBUS_VIRT_BASE)

			ret = -ENXIO;