[PATCH 1/3] hwmon: (pmbus/max34440): block unsupported VIN and IIN limit registers
From: Alexis Czezar Torreno
Date: Thu Jul 16 2026 - 04:29:23 EST
MAX34451 and ADPM chips do not support standard PMBus VIN/IIN limit
registers, manufacturer specific min/max registers, or undercurrent
or undertemperature fault limits. STATUS_BYTE and STATUS_OTHER are also
not available. Accessing these non-existent registers during driver
initialization triggers a CML error and asserts ALERT. Handled by
blocking these functions during read/write.
Fixes: 7a001dbab4ad ("hwmon: (pmbus/max34440) Add support for MAX34451.")
Fixes: 629cf8f6c23a ("hwmon: (pmbus/max34440) Add support for ADPM12160")
Fixes: 2e0b52f1ae88 ("hwmon: (pmbus/max34440): add support adpm12200")
Fixes: 479bfeba2eb6 ("hwmon: (pmbus/max34440): add support adpm12250")
Tested-by: Alexis Czezar Torreno <alexisczezar.torreno@xxxxxxxxxx>
Signed-off-by: Alexis Czezar Torreno <alexisczezar.torreno@xxxxxxxxxx>
---
drivers/hwmon/pmbus/max34440.c | 80 ++++++++++++++++++++++++++++++++++++++++++
1 file changed, 80 insertions(+)
diff --git a/drivers/hwmon/pmbus/max34440.c b/drivers/hwmon/pmbus/max34440.c
index 74876d2207fbe4014b8b54a9fd9682370fc3bbed..e56057e9273c1639bddbaf4e665ea159f1d7c3ed 100644
--- a/drivers/hwmon/pmbus/max34440.c
+++ b/drivers/hwmon/pmbus/max34440.c
@@ -88,6 +88,33 @@ static int max34440_read_word_data(struct i2c_client *client, int page,
ret = pmbus_read_word_data(client, page, phase,
data->iout_oc_warn_limit);
break;
+ case PMBUS_VIN_OV_FAULT_LIMIT:
+ case PMBUS_VIN_OV_WARN_LIMIT:
+ case PMBUS_VIN_UV_WARN_LIMIT:
+ case PMBUS_VIN_UV_FAULT_LIMIT:
+ case PMBUS_MFR_VIN_MIN:
+ case PMBUS_MFR_VIN_MAX:
+ case PMBUS_IIN_OC_WARN_LIMIT:
+ case PMBUS_IIN_OC_FAULT_LIMIT:
+ case PMBUS_MFR_IIN_MAX:
+ case PMBUS_MFR_VOUT_MIN:
+ case PMBUS_MFR_VOUT_MAX:
+ case PMBUS_IOUT_UC_FAULT_LIMIT:
+ case PMBUS_MFR_IOUT_MAX:
+ case PMBUS_UT_WARN_LIMIT:
+ case PMBUS_UT_FAULT_LIMIT:
+ case PMBUS_MFR_MAX_TEMP_1:
+ /*
+ * MAX34451/ADPM family do not support VIN/IIN limit registers,
+ * manufacturer-specific min/max registers, or undercurrent/
+ * undertemperature fault limits. Accessing these triggers CML
+ * error and asserts ALERT.
+ */
+ if (data->id == max34451 || data->id == adpm12160 ||
+ data->id == adpm12200 || data->id == adpm12250)
+ return -ENXIO;
+ ret = -ENODATA;
+ break;
case PMBUS_VIRT_READ_VOUT_MIN:
ret = pmbus_read_word_data(client, page, phase,
MAX34440_MFR_VOUT_MIN);
@@ -244,6 +271,51 @@ static int max34440_read_byte_data(struct i2c_client *client, int page, int reg)
return ret;
}
+static int max34451_read_byte_data(struct i2c_client *client, int page, int reg)
+{
+ const struct pmbus_driver_info *info = pmbus_get_driver_info(client);
+ const struct max34440_data *data = to_max34440_data(info);
+
+ switch (reg) {
+ case PMBUS_STATUS_BYTE:
+ case PMBUS_STATUS_OTHER:
+ /*
+ * MAX34451/ADPM family do not support STATUS_BYTE or
+ * STATUS_OTHER registers. Accessing them triggers CML
+ * error and asserts ALERT.
+ */
+ if (data->id == max34451 || data->id == adpm12160 ||
+ data->id == adpm12200 || data->id == adpm12250)
+ return -ENXIO;
+ return -ENODATA;
+ default:
+ return -ENODATA;
+ }
+}
+
+static int max34451_write_byte_data(struct i2c_client *client, int page,
+ int reg, u8 byte)
+{
+ const struct pmbus_driver_info *info = pmbus_get_driver_info(client);
+ const struct max34440_data *data = to_max34440_data(info);
+
+ switch (reg) {
+ case PMBUS_STATUS_BYTE:
+ case PMBUS_STATUS_OTHER:
+ /*
+ * MAX34451/ADPM family do not support STATUS_BYTE or
+ * STATUS_OTHER registers. Writing to them triggers CML
+ * error and asserts ALERT.
+ */
+ if (data->id == max34451 || data->id == adpm12160 ||
+ data->id == adpm12200 || data->id == adpm12250)
+ return -ENXIO;
+ return -ENODATA;
+ default:
+ return -ENODATA;
+ }
+}
+
static int max34451_set_supported_funcs(struct i2c_client *client,
struct max34440_data *data)
{
@@ -363,7 +435,9 @@ static struct pmbus_driver_info max34440_info[] = {
.func[9] = PMBUS_HAVE_VIN | PMBUS_HAVE_STATUS_INPUT,
.func[10] = PMBUS_HAVE_IIN | PMBUS_HAVE_STATUS_INPUT,
.func[18] = PMBUS_HAVE_TEMP | PMBUS_HAVE_STATUS_TEMP,
+ .read_byte_data = max34451_read_byte_data,
.read_word_data = max34440_read_word_data,
+ .write_byte_data = max34451_write_byte_data,
.write_word_data = max34440_write_word_data,
},
[adpm12200] = {
@@ -399,7 +473,9 @@ static struct pmbus_driver_info max34440_info[] = {
.func[10] = PMBUS_HAVE_IIN | PMBUS_HAVE_STATUS_INPUT,
.func[14] = PMBUS_HAVE_IOUT,
.func[18] = PMBUS_HAVE_TEMP | PMBUS_HAVE_STATUS_TEMP,
+ .read_byte_data = max34451_read_byte_data,
.read_word_data = max34440_read_word_data,
+ .write_byte_data = max34451_write_byte_data,
.write_word_data = max34440_write_word_data,
},
[adpm12250] = {
@@ -433,7 +509,9 @@ static struct pmbus_driver_info max34440_info[] = {
.func[10] = PMBUS_HAVE_IIN | PMBUS_HAVE_STATUS_INPUT,
.func[14] = PMBUS_HAVE_IOUT,
.func[18] = PMBUS_HAVE_TEMP | PMBUS_HAVE_STATUS_TEMP,
+ .read_byte_data = max34451_read_byte_data,
.read_word_data = max34440_read_word_data,
+ .write_byte_data = max34451_write_byte_data,
.write_word_data = max34440_write_word_data,
},
[max34440] = {
@@ -581,7 +659,9 @@ static struct pmbus_driver_info max34440_info[] = {
.func[18] = PMBUS_HAVE_TEMP | PMBUS_HAVE_STATUS_TEMP,
.func[19] = PMBUS_HAVE_TEMP | PMBUS_HAVE_STATUS_TEMP,
.func[20] = PMBUS_HAVE_TEMP | PMBUS_HAVE_STATUS_TEMP,
+ .read_byte_data = max34451_read_byte_data,
.read_word_data = max34440_read_word_data,
+ .write_byte_data = max34451_write_byte_data,
.write_word_data = max34440_write_word_data,
.page_change_delay = MAX34440_PAGE_CHANGE_DELAY,
},
--
2.34.1