[PATCH 0/3] hwmon: (pmbus/max34440): Bug fixes and supporting new device

[PATCH 0/3] hwmon: (pmbus/max34440): Bug fixes and supporting new device

[Alexis Czezar Torreno]

This series fixes register access issues in MAX34451/ADPM devices and adds
support for newer MAX34451 variants and the MAX34452 device.

The first patch addresses an issue where the driver attempts to access
unsupported registers on MAX34451 and ADPM devices, causing CML errors and
triggering ALERT.

The second patch adds support for the newer MAX34451ETNA8+ silicon revision
which uses different direct format coefficients for voltage and current
measurements.

The third patch introduces support for the MAX34452, a 16-channel voltage/
current monitor that shares a similar architecture with MAX34451.

Signed-off-by: Alexis Czezar Torreno <alexisczezar.torreno@analog.com>
---
Alexis Czezar Torreno (2):
      hwmon: (pmbus/max34440): block unsupported VIN and IIN limit registers
      hwmon: (pmbus/max34440): add support for newer version of max34451

Carlos Jones Jr (1):
      hwmon: (pmbus/max34440): Add support for MAX34452

 Documentation/hwmon/max34440.rst |  26 ++++---
 drivers/hwmon/pmbus/Kconfig      |   5 +-
 drivers/hwmon/pmbus/max34440.c   | 150 ++++++++++++++++++++++++++++++++++++---
 3 files changed, 162 insertions(+), 19 deletions(-)
---
base-commit: ca078d004cf58137bcf8cb24a8b271397431ba58
change-id: 20260716-max34451_fixes-788edb623116

Best regards,
-- 
Alexis Czezar Torreno <alexisczezar.torreno@analog.com>

[PATCH 1/3] hwmon: (pmbus/max34440): block unsupported VIN and IIN limit registers

[Alexis Czezar Torreno]

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@analog.com>
Signed-off-by: Alexis Czezar Torreno <alexisczezar.torreno@analog.com>
---
 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

Re: [PATCH 1/3] hwmon: (pmbus/max34440): block unsupported VIN and IIN limit registers

[sashiko-bot]

> 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@analog.com>
> Signed-off-by: Alexis Czezar Torreno <alexisczezar.torreno@analog.com>

Sashiko has reviewed this patch and found no issues. It looks great!

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260716-max34451_fixes-v1-0-a941b27eaecb@analog.com?part=1

[PATCH 2/3] hwmon: (pmbus/max34440): add support for newer version of max34451

[Alexis Czezar Torreno]

The MAX34451 released a newer version called max34451etna8+.
This simply changes the direct format coefficients

Signed-off-by: Alexis Czezar Torreno <alexisczezar.torreno@analog.com>
---
 drivers/hwmon/pmbus/max34440.c | 21 +++++++++++++++++----
 1 file changed, 17 insertions(+), 4 deletions(-)

diff --git a/drivers/hwmon/pmbus/max34440.c b/drivers/hwmon/pmbus/max34440.c
index e56057e9273c1639bddbaf4e665ea159f1d7c3ed..024109df26db568a4c230c9dbc45d69ba531dd8d 100644
--- a/drivers/hwmon/pmbus/max34440.c
+++ b/drivers/hwmon/pmbus/max34440.c
@@ -59,6 +59,7 @@ enum chips {
 #define MAX34440_IOUT_OC_FAULT_LIMIT	0x4A
 
 #define MAX34451ETNA6_MFR_REV		0x0012
+#define MAX34451ETNA8_MFR_REV		0x0014
 
 #define MAX34451_MFR_CHANNEL_CONFIG	0xe4
 #define MAX34451_MFR_CHANNEL_CONFIG_SEL_MASK	0x3f
@@ -343,12 +344,24 @@ static int max34451_set_supported_funcs(struct i2c_client *client,
 		max34451_na6 = true;
 		data->info.format[PSC_VOLTAGE_IN] = direct;
 		data->info.format[PSC_CURRENT_IN] = direct;
-		data->info.m[PSC_VOLTAGE_IN] = 1;
+
 		data->info.b[PSC_VOLTAGE_IN] = 0;
-		data->info.R[PSC_VOLTAGE_IN] = 3;
-		data->info.m[PSC_CURRENT_IN] = 1;
 		data->info.b[PSC_CURRENT_IN] = 0;
-		data->info.R[PSC_CURRENT_IN] = 2;
+		if (rv == MAX34451ETNA8_MFR_REV) {
+			data->info.m[PSC_VOLTAGE_IN] = 125;
+			data->info.R[PSC_VOLTAGE_IN] = 0;
+			data->info.m[PSC_VOLTAGE_OUT] = 125;
+			data->info.R[PSC_VOLTAGE_OUT] = 0;
+			data->info.m[PSC_CURRENT_IN] = 250;
+			data->info.R[PSC_CURRENT_IN] = -1;
+			data->info.m[PSC_CURRENT_OUT] = 250;
+			data->info.R[PSC_CURRENT_OUT] = -1;
+		} else {
+			data->info.m[PSC_VOLTAGE_IN] = 1;
+			data->info.R[PSC_VOLTAGE_IN] = 3;
+			data->info.m[PSC_CURRENT_IN] = 1;
+			data->info.R[PSC_CURRENT_IN] = 2;
+		}
 		data->iout_oc_fault_limit = PMBUS_IOUT_OC_FAULT_LIMIT;
 		data->iout_oc_warn_limit = PMBUS_IOUT_OC_WARN_LIMIT;
 	}

-- 
2.34.1

Re: [PATCH 2/3] hwmon: (pmbus/max34440): add support for newer version of max34451

[sashiko-bot]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Medium] Forward compatibility issue in ETNA8+ revision check due to strict equality
--

--- Patch [2]: [PATCH 2/3] hwmon: (pmbus/max34440): add support for newer version of max34451 ---
commit 02e46b67255562393d163820572cc52a0cabe3e7
Author: Alexis Czezar Torreno <alexisczezar.torreno@analog.com>

hwmon: (pmbus/max34440): add support for newer version of max34451

This commit adds support for the max34451etna8+ hardware revision.
It updates the direct format coefficients specifically for this newer
revision.

> diff --git a/drivers/hwmon/pmbus/max34440.c b/drivers/hwmon/pmbus/max34440.c
> index e56057e9273c1..024109df26db5 100644
> --- a/drivers/hwmon/pmbus/max34440.c
> +++ b/drivers/hwmon/pmbus/max34440.c

[ ... ]

> @@ -343,12 +344,24 @@ static int max34451_set_supported_funcs(struct i2c_client *client,
>  		max34451_na6 = true;
>  		data->info.format[PSC_VOLTAGE_IN] = direct;
>  		data->info.format[PSC_CURRENT_IN] = direct;
> -		data->info.m[PSC_VOLTAGE_IN] = 1;
> +
>  		data->info.b[PSC_VOLTAGE_IN] = 0;
> -		data->info.R[PSC_VOLTAGE_IN] = 3;
> -		data->info.m[PSC_CURRENT_IN] = 1;
>  		data->info.b[PSC_CURRENT_IN] = 0;
> -		data->info.R[PSC_CURRENT_IN] = 2;
> +		if (rv == MAX34451ETNA8_MFR_REV) {

[Severity: Medium]
Will this strict equality check cause issues with future hardware revisions?

The commit message mentions adding support for the ETNA8+ version, but if a
subsequent hardware revision probes with a manufacturer revision greater than
MAX34451ETNA8_MFR_REV (e.g., 0x0015), the outer check
rv >= MAX34451ETNA6_MFR_REV will evaluate to true, but this inner check will
fail.

This causes the code to silently fall through to the else block, regressing to
the older ETNA6 coefficients rather than retaining the newer ETNA8 ones.

Could this use >= instead of == to maintain forward compatibility, similar
to how ETNA6 is checked on line 328?

> +			data->info.m[PSC_VOLTAGE_IN] = 125;
> +			data->info.R[PSC_VOLTAGE_IN] = 0;
> +			data->info.m[PSC_VOLTAGE_OUT] = 125;
> +			data->info.R[PSC_VOLTAGE_OUT] = 0;
> +			data->info.m[PSC_CURRENT_IN] = 250;
> +			data->info.R[PSC_CURRENT_IN] = -1;
> +			data->info.m[PSC_CURRENT_OUT] = 250;
> +			data->info.R[PSC_CURRENT_OUT] = -1;
> +		} else {
> +			data->info.m[PSC_VOLTAGE_IN] = 1;
> +			data->info.R[PSC_VOLTAGE_IN] = 3;
> +			data->info.m[PSC_CURRENT_IN] = 1;
> +			data->info.R[PSC_CURRENT_IN] = 2;
> +		}
>  		data->iout_oc_fault_limit = PMBUS_IOUT_OC_FAULT_LIMIT;
>  		data->iout_oc_warn_limit = PMBUS_IOUT_OC_WARN_LIMIT;
>  	}

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260716-max34451_fixes-v1-0-a941b27eaecb@analog.com?part=2

[PATCH 3/3] hwmon: (pmbus/max34440): Add support for MAX34452

[Alexis Czezar Torreno]

From: Carlos Jones Jr <carlosjr.jones@analog.com>

Add support for Maxim MAX34452 PMBus 16-Channel V/I Monitor and
12-Channel Sequencer/Marginer. The device is similar to MAX34451
and shares the same configuration function.

The MAX34452 supports:
- 16 configurable voltage/current monitoring channels
- 5 temperature sensors (pages 16-20)
- Dynamic channel configuration via MFR_CHANNEL_CONFIG
- IOUT average monitoring

Signed-off-by: Carlos Jones Jr <carlosjr.jones@analog.com>
Co-Developed by: Alexis Czezar Torreno <alexisczezar.torreno@analog.com>
Signed-off-by: Alexis Czezar Torreno <alexisczezar.torreno@analog.com>
---
 Documentation/hwmon/max34440.rst | 26 +++++++++++------
 drivers/hwmon/pmbus/Kconfig      |  5 ++--
 drivers/hwmon/pmbus/max34440.c   | 61 ++++++++++++++++++++++++++++++++--------
 3 files changed, 71 insertions(+), 21 deletions(-)

diff --git a/Documentation/hwmon/max34440.rst b/Documentation/hwmon/max34440.rst
index e7421f4dbf38fc1436bbaeba71d4461a00f8cefb..866f22b88e9b360ff54aa52807484bb3e859e56e 100644
--- a/Documentation/hwmon/max34440.rst
+++ b/Documentation/hwmon/max34440.rst
@@ -65,6 +65,16 @@ Supported chips:
 
     Datasheet: https://www.analog.com/media/en/technical-documentation/data-sheets/max34451.pdf
 
+  * Maxim MAX34452
+
+    PMBus 16-Channel V/I Monitor and 12-Channel Sequencer/Marginer
+
+    Prefixes: 'max34452'
+
+    Addresses scanned: -
+
+    Datasheet: -
+
   * Maxim MAX34460
 
     PMBus 12-Channel Voltage Monitor & Sequencer
@@ -94,11 +104,11 @@ Description
 This driver supports multiple devices: hardware monitoring for Maxim MAX34440
 PMBus 6-Channel Power-Supply Manager, MAX34441 PMBus 5-Channel Power-Supply
 Manager and Intelligent Fan Controller, and MAX34446 PMBus Power-Supply Data
-Logger; PMBus Voltage Monitor and Sequencers for MAX34451, MAX34460, and
-MAX34461; PMBus DC/DC Power Module ADPM12160, ADPM12200, and ADPM12250. The
-MAX34451 supports monitoring voltage or current of 12 channels based on GIN
-pins. The MAX34460 supports 12 voltage channels, and the MAX34461 supports 16
-voltage channels. The ADPM12160, ADPM12200, and ADPM12250 also monitors both
+Logger; PMBus Voltage Monitor and Sequencers for MAX34451, MAX34452, MAX34460,
+and MAX34461; PMBus DC/DC Power Module ADPM12160, ADPM12200, and ADPM12250. The
+MAX34451 and MAX34452 support monitoring voltage or current of 16 channels based
+on GIN pins. The MAX34460 supports 12 voltage channels, and the MAX34461 supports
+16 voltage channels. The ADPM12160, ADPM12200, and ADPM12250 also monitor both
 input and output of voltage and current.
 
 The driver is a client driver to the core PMBus driver. Please see
@@ -171,7 +181,7 @@ curr[1-6]_crit		Critical maximum current. From IOUT_OC_FAULT_LIMIT
 			register.
 curr[1-6]_max_alarm	Current high alarm. From IOUT_OC_WARNING status.
 curr[1-6]_crit_alarm	Current critical high alarm. From IOUT_OC_FAULT status.
-curr[1-4]_average	Historical average current (MAX34446/34451 only).
+curr[1-4]_average	Historical average current (MAX34446/34451/34452 only).
 curr[1-6]_highest	Historical maximum current.
 curr[1-6]_reset_history	Write any value to reset history.
 ======================= ========================================================
@@ -223,7 +233,7 @@ temp[1-8]_reset_history	Write any value to reset history.
 
 .. note::
 
-   - MAX34451 supports attribute groups in[1-16] (or curr[1-16] based on
-     input pins) and temp[1-5].
+   - MAX34451 and MAX34452 support attribute groups in[1-16] (or curr[1-16]
+     based on input pins) and temp[1-5].
    - MAX34460 supports attribute groups in[1-12] and temp[1-5].
    - MAX34461 supports attribute groups in[1-16] and temp[1-5].
diff --git a/drivers/hwmon/pmbus/Kconfig b/drivers/hwmon/pmbus/Kconfig
index ae003a6eac30a7b0a022c5f7f467d8f81736c3f7..91fa1c19e87c9f2de789f2908e59ac00c228eb76 100644
--- a/drivers/hwmon/pmbus/Kconfig
+++ b/drivers/hwmon/pmbus/Kconfig
@@ -434,8 +434,9 @@ config SENSORS_MAX34440
 	tristate "Maxim MAX34440 and compatibles"
 	help
 	  If you say yes here you get hardware monitoring support for Maxim
-	  MAX34440, MAX34441, MAX34446, MAX34451, MAX34460, and MAX34461.
-	  Other compatible are ADPM12160, and ADPM12200.
+	  MAX34440, MAX34441, MAX34446, MAX34451, MAX34452, MAX34460, and
+	  MAX34461. Other compatible devices are ADPM12160, ADPM12200, and
+	  ADPM12250.
 
 	  This driver can also be built as a module. If so, the module will
 	  be called max34440.
diff --git a/drivers/hwmon/pmbus/max34440.c b/drivers/hwmon/pmbus/max34440.c
index 024109df26db568a4c230c9dbc45d69ba531dd8d..2e57af09f47809b0a0bddab27fc47cadfe35e0ef 100644
--- a/drivers/hwmon/pmbus/max34440.c
+++ b/drivers/hwmon/pmbus/max34440.c
@@ -23,6 +23,7 @@ enum chips {
 	max34441,
 	max34446,
 	max34451,
+	max34452,
 	max34460,
 	max34461,
 };
@@ -116,6 +117,10 @@ static int max34440_read_word_data(struct i2c_client *client, int page,
 			return -ENXIO;
 		ret = -ENODATA;
 		break;
+	case PMBUS_VOUT_OV_WARN_LIMIT:
+		if (data->id == max34452)
+			return -ENXIO;
+		return -ENODATA;
 	case PMBUS_VIRT_READ_VOUT_MIN:
 		ret = pmbus_read_word_data(client, page, phase,
 					   MAX34440_MFR_VOUT_MIN);
@@ -126,8 +131,8 @@ static int max34440_read_word_data(struct i2c_client *client, int page,
 		break;
 	case PMBUS_VIRT_READ_IOUT_AVG:
 		if (data->id != max34446 && data->id != max34451 &&
-		    data->id != adpm12160 && data->id != adpm12200 &&
-		    data->id != adpm12250)
+		    data->id != max34452 && data->id != adpm12160 &&
+		    data->id != adpm12200 && data->id != adpm12250)
 			return -ENXIO;
 		ret = pmbus_read_word_data(client, page, phase,
 					   MAX34446_MFR_IOUT_AVG);
@@ -192,6 +197,10 @@ static int max34440_write_word_data(struct i2c_client *client, int page,
 		ret = pmbus_write_word_data(client, page, data->iout_oc_warn_limit,
 					    word);
 		break;
+	case PMBUS_VOUT_OV_WARN_LIMIT:
+		if (data->id == max34452)
+			return -ENXIO;
+		return -ENODATA;
 	case PMBUS_VIRT_RESET_POUT_HISTORY:
 		ret = pmbus_write_word_data(client, page,
 					    MAX34446_MFR_POUT_PEAK, 0);
@@ -212,8 +221,8 @@ static int max34440_write_word_data(struct i2c_client *client, int page,
 		ret = pmbus_write_word_data(client, page,
 					    MAX34440_MFR_IOUT_PEAK, 0);
 		if (!ret && (data->id == max34446 || data->id == max34451 ||
-			     data->id == adpm12160 || data->id == adpm12200 ||
-			     data->id == adpm12250))
+			     data->id == max34452 || data->id == adpm12160 ||
+			     data->id == adpm12200 || data->id == adpm12250))
 			ret = pmbus_write_word_data(client, page,
 					MAX34446_MFR_IOUT_AVG, 0);
 
@@ -281,12 +290,13 @@ static int max34451_read_byte_data(struct i2c_client *client, int page, int reg)
 	case PMBUS_STATUS_BYTE:
 	case PMBUS_STATUS_OTHER:
 		/*
-		 * MAX34451/ADPM family do not support STATUS_BYTE or
+		 * MAX34451/MAX34452/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)
+		if (data->id == max34451 || data->id == max34452 ||
+		    data->id == adpm12160 || data->id == adpm12200 ||
+		    data->id == adpm12250)
 			return -ENXIO;
 		return -ENODATA;
 	default:
@@ -304,12 +314,13 @@ static int max34451_write_byte_data(struct i2c_client *client, int page,
 	case PMBUS_STATUS_BYTE:
 	case PMBUS_STATUS_OTHER:
 		/*
-		 * MAX34451/ADPM family do not support STATUS_BYTE or
+		 * MAX34451/MAX34452/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)
+		if (data->id == max34451 || data->id == max34452 ||
+		    data->id == adpm12160 || data->id == adpm12200 ||
+		    data->id == adpm12250)
 			return -ENXIO;
 		return -ENODATA;
 	default:
@@ -340,6 +351,7 @@ static int max34451_set_supported_funcs(struct i2c_client *client,
 	if (rv < 0)
 		return rv;
 
+	/* MAX34452's latest MFR_REV is only at 0x0004, will skip this part */
 	if (rv >= MAX34451ETNA6_MFR_REV) {
 		max34451_na6 = true;
 		data->info.format[PSC_VOLTAGE_IN] = direct;
@@ -678,6 +690,32 @@ static struct pmbus_driver_info max34440_info[] = {
 		.write_word_data = max34440_write_word_data,
 		.page_change_delay = MAX34440_PAGE_CHANGE_DELAY,
 	},
+	[max34452] = {
+		.pages = 21,
+		.format[PSC_VOLTAGE_OUT] = direct,
+		.format[PSC_TEMPERATURE] = direct,
+		.format[PSC_CURRENT_OUT] = direct,
+		.m[PSC_VOLTAGE_OUT] = 1,
+		.b[PSC_VOLTAGE_OUT] = 0,
+		.R[PSC_VOLTAGE_OUT] = 3,
+		.m[PSC_CURRENT_OUT] = 1,
+		.b[PSC_CURRENT_OUT] = 0,
+		.R[PSC_CURRENT_OUT] = 2,
+		.m[PSC_TEMPERATURE] = 1,
+		.b[PSC_TEMPERATURE] = 0,
+		.R[PSC_TEMPERATURE] = 2,
+		/* func 0-15 is set dynamically before probing */
+		.func[16] = PMBUS_HAVE_TEMP | PMBUS_HAVE_STATUS_TEMP,
+		.func[17] = PMBUS_HAVE_TEMP | PMBUS_HAVE_STATUS_TEMP,
+		.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,
+	},
 	[max34460] = {
 		.pages = 18,
 		.format[PSC_VOLTAGE_OUT] = direct,
@@ -761,7 +799,7 @@ static int max34440_probe(struct i2c_client *client)
 	data->iout_oc_fault_limit = MAX34440_IOUT_OC_FAULT_LIMIT;
 	data->iout_oc_warn_limit = MAX34440_IOUT_OC_WARN_LIMIT;
 
-	if (data->id == max34451) {
+	if (data->id == max34451 || data->id == max34452) {
 		rv = max34451_set_supported_funcs(client, data);
 		if (rv)
 			return rv;
@@ -782,6 +820,7 @@ static const struct i2c_device_id max34440_id[] = {
 	{ .name = "max34441", .driver_data = max34441 },
 	{ .name = "max34446", .driver_data = max34446 },
 	{ .name = "max34451", .driver_data = max34451 },
+	{ .name = "max34452", .driver_data = max34452 },
 	{ .name = "max34460", .driver_data = max34460 },
 	{ .name = "max34461", .driver_data = max34461 },
 	{ }

-- 
2.34.1

Re: [PATCH 3/3] hwmon: (pmbus/max34440): Add support for MAX34452

[sashiko-bot]

Thank you for your contribution! Sashiko AI review found 2 potential issue(s) to consider:
- [High] Missing unsupported register masking causes CML errors and ALERT pin assertions during probe for max34452.
- [Medium] Brittle hardware revision check assumes max34452 will never reach MAX34451's NA6 revision threshold, risking future hardware misconfiguration.
--

--- Patch [3]: [PATCH 3/3] hwmon: (pmbus/max34440): Add support for MAX34452 ---
commit 35474250b6c0fdacb08c3d70de3d117a0f87d0c2
Author: Carlos Jones Jr <carlosjr.jones@analog.com>

hwmon: (pmbus/max34440): Add support for MAX34452

This commit adds support for the Maxim MAX34452 PMBus 16-Channel V/I Monitor
and 12-Channel Sequencer/Marginer. The device is similar to the MAX34451 and
shares the same configuration functions.

> diff --git a/drivers/hwmon/pmbus/max34440.c b/drivers/hwmon/pmbus/max34440.c
> index 024109df26db5..2e57af09f4780 100644
> --- a/drivers/hwmon/pmbus/max34440.c
> +++ b/drivers/hwmon/pmbus/max34440.c

[ ... ]

> @@ -116,6 +117,10 @@ static int max34440_read_word_data(struct i2c_client *client, int page,
>  			return -ENXIO;
>  		ret = -ENODATA;
>  		break;

[Severity: High]
Does the preceding switch case block (for PMBUS_VIN_OV_FAULT_LIMIT,
PMBUS_MFR_MAX_TEMP_1, etc.) also need to exclude max34452, similar to how it
currently excludes max34451?

Because max34452 enables PMBUS_HAVE_TEMP and PMBUS_HAVE_IOUT, the PMBus core
will dynamically query limit registers during probe. Since max34452 isn't
excluded in that preceding check, it returns -ENODATA instead of -ENXIO. This
causes the core to perform physical I2C reads on unsupported registers, which
can trigger CML errors and assert the hardware ALERT pin on the max34452.

> +	case PMBUS_VOUT_OV_WARN_LIMIT:
> +		if (data->id == max34452)
> +			return -ENXIO;
> +		return -ENODATA;
>  	case PMBUS_VIRT_READ_VOUT_MIN:

[ ... ]

> @@ -340,6 +351,7 @@ static int max34451_set_supported_funcs(struct i2c_client *client,
>  	if (rv < 0)
>  		return rv;
>  
> +	/* MAX34452's latest MFR_REV is only at 0x0004, will skip this part */
>  	if (rv >= MAX34451ETNA6_MFR_REV) {
>  		max34451_na6 = true;
>  		data->info.format[PSC_VOLTAGE_IN] = direct;

[Severity: Medium]
Will this cause issues if a future max34452 silicon revision increments its
MFR_REVISION to 0x0012 (MAX34451ETNA6_MFR_REV) or higher?

Since the check relies solely on the revision number without explicitly
verifying if the device ID is max34451, a future max34452 revision could
mistakenly trigger this MAX34451-specific silicon workaround. This would
unintentionally enable VIN/IIN channels and alter IOUT scale factors.

Could we check the device ID explicitly here to prevent this?

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260716-max34451_fixes-v1-0-a941b27eaecb@analog.com?part=3