[PATCH] hwmon: (pmbus/bpa-rs600): Handle Vin readings >= 256V
From: Chris Packham <chris.packham@alliedtelesis.co.nz>
Date: 2021-06-16 03:42:29
Also in:
lkml
Subsystem:
hardware monitoring, the rest · Maintainers:
Guenter Roeck, Linus Torvalds
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: 15b2703e5e02 ("hwmon: (pmbus) Add driver for BluTek BPA-RS600")
Signed-off-by: Chris Packham <chris.packham@alliedtelesis.co.nz>
---
drivers/hwmon/pmbus/bpa-rs600.c | 29 +++++++++++++++++++++++++++++
1 file changed, 29 insertions(+)
diff --git a/drivers/hwmon/pmbus/bpa-rs600.c b/drivers/hwmon/pmbus/bpa-rs600.c
index f6558ee9dec3..2be69fedfa36 100644
--- a/drivers/hwmon/pmbus/bpa-rs600.c
+++ b/drivers/hwmon/pmbus/bpa-rs600.c@@ -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;
--
2.31.1