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Message-Id: <20210712061000.048528747@linuxfoundation.org>
Date: Mon, 12 Jul 2021 08:05:43 +0200
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-kernel@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
stable@...r.kernel.org,
Chris Packham <chris.packham@...iedtelesis.co.nz>,
Guenter Roeck <linux@...ck-us.net>,
Sasha Levin <sashal@...nel.org>
Subject: [PATCH 5.13 320/800] hwmon: (pmbus/bpa-rs600) Handle Vin readings >= 256V
From: Chris Packham <chris.packham@...iedtelesis.co.nz>
[ Upstream commit 6e9ef8ca687e69e9d4cc89033d98e06350b0f3e0 ]
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@...iedtelesis.co.nz>
Link: https://lore.kernel.org/r/20210616034218.25821-1-chris.packham@alliedtelesis.co.nz
Signed-off-by: Guenter Roeck <linux@...ck-us.net>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
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;
--
2.30.2
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