[PATCH 0/2] hwmon: (coretemp) Documentation and TjMax table updates

[PATCH 0/2] hwmon: (coretemp) Documentation and TjMax table updates

[Laveesh Bansal]

This series updates the coretemp driver documentation and adds TjMax
fallback values for Intel Atom processors from Silvermont through
Tremont microarchitectures.

Note: These TjMax values are derived from Intel ARK and official
datasheets. The table entries serve as fallbacks when
MSR_IA32_TEMPERATURE_TARGET reads fail (e.g., in some virtualization
scenarios or locked BIOS configurations). This follows the existing
pattern for older Atoms (Bonnell, Saltwell) which also have fallback
entries despite supporting the MSR. I don't have physical access to
all processors listed — testing feedback welcome.

Patch 1 - Documentation update:
- Extend supported CPU model list with newer Atom processors
- Clarify that X86_FEATURE_DTHERM is the actual detection mechanism
- Update per-package temperature description for Sandy Bridge and newer
- Document that TjMax is read from MSR_IA32_TEMPERATURE_TARGET
- Add TjMax values for 22nm, 14nm, and 10nm Atoms to Appendix A

Patch 2 - Code change:
- Add TjMax fallback entries to tjmax_model_table[] for:
  - INTEL_ATOM_SILVERMONT (0x37): stepping 9 = 110C, other = 90C
  - INTEL_ATOM_SILVERMONT_MID (0x4a, Merrifield): 90C
  - INTEL_ATOM_SILVERMONT_MID2 (0x5a, Moorefield): 90C
  - INTEL_ATOM_AIRMONT (0x4c, Cherry Trail): 90C
  - INTEL_ATOM_GOLDMONT (0x5c, Apollo Lake): 105C
  - INTEL_ATOM_GOLDMONT_PLUS (0x7a, Gemini Lake): 105C
  - INTEL_ATOM_TREMONT (0x96, Elkhart Lake): 105C
  - INTEL_ATOM_TREMONT_L (0x9c, Jasper Lake): 105C

TjMax sources (Intel ARK and datasheets):
- Bay Trail E38xx (110C): https://ark.intel.com/content/www/us/en/ark/products/78475/intel-atom-processor-e3845.html
- Bay Trail Z37xx (90C): https://www.intel.com/content/dam/www/public/us/en/documents/datasheets/atom-z36xxx-z37xxx-datasheet-vol-1.pdf
- Cherry Trail (90C): https://ark.intel.com/content/www/us/en/ark/products/93361/intel-atom-x5-z8550-processor.html
- Apollo Lake (105C): https://ark.intel.com/content/www/us/en/ark/products/95598/intel-celeron-processor-j3455.html
- Gemini Lake (105C): https://ark.intel.com/content/www/us/en/ark/products/128989/intel-celeron-processor-j4105.html
- Elkhart Lake (105C): https://www.intel.com/content/www/us/en/products/sku/207907/intel-atom-x6425e-processor-1-5m-cache-up-to-3-00-ghz/specifications.html
- Jasper Lake (105C): https://www.intel.com/content/www/us/en/products/sku/212330/intel-celeron-processor-n5100-4m-cache-up-to-2-80-ghz/specifications.html
- Bay Trail stepping: https://community.intel.com/cipcp26785/attachments/cipcp26785/embedded-atom-processors/4708/1/600834-329901-intel-atom-processor-e3800-product-family-su-rev015.pdf

Laveesh Bansal (2):
  Documentation: hwmon: coretemp: Update supported CPUs and TjMax values
  hwmon: (coretemp) Add TjMax for Silvermont through Tremont Atoms

 Documentation/hwmon/coretemp.rst | 56 ++++++++++++++++++++++++++------
 drivers/hwmon/coretemp.c         |  9 +++++
 2 files changed, 55 insertions(+), 10 deletions(-)

--
2.43.0

[PATCH 1/2] Documentation: hwmon: coretemp: Update supported CPUs and TjMax values

[Laveesh Bansal]

Update the coretemp documentation to reflect current driver capabilities:

- Extend the supported CPU model list to include Atom processors from
  Bonnell through Jasper Lake, maintaining the original format with
  model numbers and adding X86_FEATURE_DTHERM as the actual detection
  mechanism. Added models: 0x37 (Bay Trail), 0x4a (Merrifield),
  0x4c (Cherry Trail), 0x5a (Moorefield), 0x5c (Apollo Lake),
  0x7a (Gemini Lake), 0x96 (Elkhart Lake), 0x9c (Jasper Lake)

- Update the description to note that per-package temperature sensing
  is available on Sandy Bridge and all newer processors

- Clarify that TjMax is read from MSR_IA32_TEMPERATURE_TARGET on modern
  CPUs (Nehalem and newer)

- Add TjMax values for newer Atom processor families to Appendix A:
  - 22nm Silvermont/Bay Trail: E38xx at 110C, Z37xx at 90C
  - 22nm Silvermont/Moorefield: Z35xx at 90C
  - 14nm Airmont/Cherry Trail: Z8xxx at 90C
  - 14nm Goldmont/Apollo Lake: 105C
  - 14nm Goldmont Plus/Gemini Lake: 105C
  - 10nm Tremont/Elkhart Lake: 105C
  - 10nm Tremont/Jasper Lake: 105C

TjMax values obtained from Intel ARK and official datasheets:
- E3845: https://www.intel.com/content/www/us/en/products/sku/78475/intel-atom-processor-e3845-2m-cache-1-91-ghz/specifications.html
- Z3600/Z3700: https://www.intel.com/content/dam/www/public/us/en/documents/datasheets/atom-z36xxx-z37xxx-datasheet-vol-1.pdf

Signed-off-by: Laveesh Bansal <laveeshb@laveeshbansal.com>
---
 Documentation/hwmon/coretemp.rst | 56 ++++++++++++++++++++++++++------
 1 file changed, 46 insertions(+), 10 deletions(-)

diff --git a/Documentation/hwmon/coretemp.rst b/Documentation/hwmon/coretemp.rst
index c609329e3bc4..3afb179e0ced 100644
--- a/Documentation/hwmon/coretemp.rst
+++ b/Documentation/hwmon/coretemp.rst
@@ -2,17 +2,21 @@ Kernel driver coretemp
 ======================
 
 Supported chips:
-  * All Intel Core family
+  * All Intel Core family and Atom processors with Digital Thermal Sensor (DTS)
 
     Prefix: 'coretemp'
 
-    CPUID: family 0x6, models
+    CPUID: family 0x6, models with X86_FEATURE_DTHERM, including:
 
 			    - 0xe (Pentium M DC), 0xf (Core 2 DC 65nm),
 			    - 0x16 (Core 2 SC 65nm), 0x17 (Penryn 45nm),
 			    - 0x1a (Nehalem), 0x1c (Atom), 0x1e (Lynnfield),
 			    - 0x26 (Tunnel Creek Atom), 0x27 (Medfield Atom),
-			    - 0x36 (Cedar Trail Atom)
+			    - 0x36 (Cedar Trail Atom), 0x37 (Bay Trail Atom),
+			    - 0x4a (Merrifield Atom), 0x4c (Cherry Trail Atom),
+			    - 0x5a (Moorefield Atom), 0x5c (Apollo Lake Atom),
+			    - 0x7a (Gemini Lake Atom),
+			    - 0x96 (Elkhart Lake Atom), 0x9c (Jasper Lake Atom)
 
     Datasheet:
 
@@ -28,9 +32,9 @@ Description
 
 This driver permits reading the DTS (Digital Temperature Sensor) embedded
 inside Intel CPUs. This driver can read both the per-core and per-package
-temperature using the appropriate sensors. The per-package sensor is new;
-as of now, it is present only in the SandyBridge platform. The driver will
-show the temperature of all cores inside a package under a single device
+temperature using the appropriate sensors. The per-package sensor is
+available on Sandy Bridge and all newer processors. The driver will show
+the temperature of all cores inside a package under a single device
 directory inside hwmon.
 
 Temperature is measured in degrees Celsius and measurement resolution is
@@ -56,10 +60,11 @@ tempX_label	  Contains string "Core X", where X is processor
 		  where Y is the package number.
 ================= ========================================================
 
-On CPU models which support it, TjMax is read from a model-specific register.
-On other models, it is set to an arbitrary value based on weak heuristics.
-If these heuristics don't work for you, you can pass the correct TjMax value
-as a module parameter (tjmax).
+On modern CPUs (Nehalem and newer), TjMax is read from the
+MSR_IA32_TEMPERATURE_TARGET register. On older models without this MSR,
+TjMax is determined using lookup tables or heuristics. If these don't work
+for your CPU, you can pass the correct TjMax value as a module parameter
+(tjmax).
 
 Appendix A. Known TjMax lists (TBD):
 Some information comes from ark.intel.com
@@ -100,6 +105,37 @@ Process		Processor					TjMax(C)
 		D2700/2550/2500					100
 		N2850/2800/2650/2600				100
 
+22nm		Atom Processors (Silvermont/Bay Trail)
+		E3845/3827/3826/3825/3815/3805			110
+		Z3795/3775/3770/3740/3736/3735/3680		90
+
+22nm		Atom Processors (Silvermont/Moorefield)
+		Z3580/3570/3560/3530				90
+
+14nm		Atom Processors (Airmont/Cherry Trail)
+		x5-Z8550/Z8500/Z8350/Z8330/Z8300		90
+		x7-Z8750/Z8700					90
+
+14nm		Atom Processors (Goldmont/Apollo Lake)
+		x5-E3940/E3930					105
+		x7-E3950					105
+
+14nm		Celeron/Pentium Processors (Goldmont/Apollo Lake)
+		J3455/J3355					105
+		N3450/N3350					105
+		N4200						105
+
+14nm		Celeron/Pentium Processors (Goldmont Plus/Gemini Lake)
+		J4105/J4005					105
+		N4100/N4000					105
+		N5000						105
+
+10nm		Atom Processors (Tremont/Elkhart Lake)
+		x6000E						105
+
+10nm		Celeron/Pentium Processors (Tremont/Jasper Lake)
+		N4500/N5100/N6000 series			105
+
 45nm		Xeon Processors 5400 Quad-Core
 		X5492, X5482, X5472, X5470, X5460, X5450	85
 		E5472, E5462, E5450/40/30/20/10/05		85
-- 
2.43.0

[PATCH 2/2] hwmon: (coretemp) Add TjMax for Silvermont through Tremont Atoms

[Laveesh Bansal]

Add fallback TjMax values for Intel Atom processors based on Silvermont,
Airmont, Goldmont, and Tremont microarchitectures. These processors
support MSR_IA32_TEMPERATURE_TARGET for reading TjMax directly, so these
table entries serve as fallback values only when the MSR read fails
(e.g., in some virtualization scenarios).

Added processors and TjMax values:

- INTEL_ATOM_SILVERMONT (0x37, Bay Trail):
  - Stepping 9 (E38xx embedded): 110C
  - Other steppings (Z37xx tablet): 90C
  Stepping identified from Intel E3800 Specification Update.

- INTEL_ATOM_SILVERMONT_MID (0x4a, Merrifield): 90C

- INTEL_ATOM_SILVERMONT_MID2 (0x5a, Moorefield): 90C

- INTEL_ATOM_AIRMONT (0x4c, Cherry Trail): 90C

- INTEL_ATOM_GOLDMONT (0x5c, Apollo Lake): 105C

- INTEL_ATOM_GOLDMONT_PLUS (0x7a, Gemini Lake): 105C

- INTEL_ATOM_TREMONT (0x96, Elkhart Lake): 105C

- INTEL_ATOM_TREMONT_L (0x9c, Jasper Lake): 105C

Not included (MSR reads work reliably, server/specialized chips):
- INTEL_ATOM_SILVERMONT_D (Avoton): Server, Tcase 97C
- INTEL_ATOM_GOLDMONT_D (Denverton): Server, Tcase 82C
- INTEL_ATOM_AIRMONT_NP (Lightning Mountain): Network processor
- INTEL_ATOM_TREMONT_D (Jacobsville): Server
- INTEL_ATOM_GRACEMONT (Alder Lake-N): Very new, MSR works

Reference: Intel datasheets and ARK processor specifications
- Z3600/Z3700 datasheet: https://www.intel.com/content/dam/www/public/us/en/documents/datasheets/atom-z36xxx-z37xxx-datasheet-vol-1.pdf
- E3845 ARK: https://www.intel.com/content/www/us/en/products/sku/78475/intel-atom-processor-e3845-2m-cache-1-91-ghz/specifications.html
- E3800 Spec Update: https://community.intel.com/cipcp26785/attachments/cipcp26785/embedded-atom-processors/4708/1/600834-329901-intel-atom-processor-e3800-product-family-su-rev015.pdf

Signed-off-by: Laveesh Bansal <laveeshb@laveeshbansal.com>
---
 drivers/hwmon/coretemp.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/drivers/hwmon/coretemp.c b/drivers/hwmon/coretemp.c
index ad79db5a183e..d2dfa4e30407 100644
--- a/drivers/hwmon/coretemp.c
+++ b/drivers/hwmon/coretemp.c
@@ -145,6 +145,15 @@ static const struct tjmax_model tjmax_model_table[] = {
 							 * Also matches S12x0 (stepping 9), covered by
 							 * PCI table
 							 */
+	{ INTEL_ATOM_SILVERMONT,      9, 110000 },	/* Atom Bay Trail E38xx (embedded) */
+	{ INTEL_ATOM_SILVERMONT,      ANY, 90000 },	/* Atom Bay Trail Z37xx (tablet) */
+	{ INTEL_ATOM_SILVERMONT_MID,  ANY, 90000 },	/* Atom Merrifield (Z34xx) */
+	{ INTEL_ATOM_SILVERMONT_MID2, ANY, 90000 },	/* Atom Moorefield (Z35xx) */
+	{ INTEL_ATOM_AIRMONT,	      ANY, 90000 },	/* Atom Cherry Trail (Z8xxx) */
+	{ INTEL_ATOM_GOLDMONT,	      ANY, 105000 },	/* Atom Apollo Lake (J3xxx, N3xxx, E39xx) */
+	{ INTEL_ATOM_GOLDMONT_PLUS,   ANY, 105000 },	/* Atom Gemini Lake (J4xxx, N4xxx, N5xxx) */
+	{ INTEL_ATOM_TREMONT,	      ANY, 105000 },	/* Atom Elkhart Lake */
+	{ INTEL_ATOM_TREMONT_L,	      ANY, 105000 },	/* Atom Jasper Lake */
 };
 
 static bool is_pkg_temp_data(struct temp_data *tdata)
-- 
2.43.0

Re: [PATCH 1/2] Documentation: hwmon: coretemp: Update supported CPUs and TjMax values

[Guenter Roeck]

On Tue, Jan 06, 2026 at 03:54:25PM +0000, Laveesh Bansal wrote:
> Update the coretemp documentation to reflect current driver capabilities:
> 
> - Extend the supported CPU model list to include Atom processors from
>   Bonnell through Jasper Lake, maintaining the original format with
>   model numbers and adding X86_FEATURE_DTHERM as the actual detection
>   mechanism. Added models: 0x37 (Bay Trail), 0x4a (Merrifield),
>   0x4c (Cherry Trail), 0x5a (Moorefield), 0x5c (Apollo Lake),
>   0x7a (Gemini Lake), 0x96 (Elkhart Lake), 0x9c (Jasper Lake)
> 
> - Update the description to note that per-package temperature sensing
>   is available on Sandy Bridge and all newer processors
> 
> - Clarify that TjMax is read from MSR_IA32_TEMPERATURE_TARGET on modern
>   CPUs (Nehalem and newer)
> 
> - Add TjMax values for newer Atom processor families to Appendix A:
>   - 22nm Silvermont/Bay Trail: E38xx at 110C, Z37xx at 90C
>   - 22nm Silvermont/Moorefield: Z35xx at 90C
>   - 14nm Airmont/Cherry Trail: Z8xxx at 90C
>   - 14nm Goldmont/Apollo Lake: 105C
>   - 14nm Goldmont Plus/Gemini Lake: 105C
>   - 10nm Tremont/Elkhart Lake: 105C
>   - 10nm Tremont/Jasper Lake: 105C
> 
> TjMax values obtained from Intel ARK and official datasheets:
> - E3845: https://www.intel.com/content/www/us/en/products/sku/78475/intel-atom-processor-e3845-2m-cache-1-91-ghz/specifications.html
> - Z3600/Z3700: https://www.intel.com/content/dam/www/public/us/en/documents/datasheets/atom-z36xxx-z37xxx-datasheet-vol-1.pdf
> 
> Signed-off-by: Laveesh Bansal <laveeshb@laveeshbansal.com>

Applied.

Thanks,
Guenter

Re: [PATCH 2/2] hwmon: (coretemp) Add TjMax for Silvermont through Tremont Atoms

[Guenter Roeck]

On Tue, Jan 06, 2026 at 03:54:26PM +0000, Laveesh Bansal wrote:
> Add fallback TjMax values for Intel Atom processors based on Silvermont,
> Airmont, Goldmont, and Tremont microarchitectures. These processors
> support MSR_IA32_TEMPERATURE_TARGET for reading TjMax directly, so these
> table entries serve as fallback values only when the MSR read fails
> (e.g., in some virtualization scenarios).
> 
> Added processors and TjMax values:
> 
> - INTEL_ATOM_SILVERMONT (0x37, Bay Trail):
>   - Stepping 9 (E38xx embedded): 110C
>   - Other steppings (Z37xx tablet): 90C
>   Stepping identified from Intel E3800 Specification Update.
> 
> - INTEL_ATOM_SILVERMONT_MID (0x4a, Merrifield): 90C
> 
> - INTEL_ATOM_SILVERMONT_MID2 (0x5a, Moorefield): 90C
> 
> - INTEL_ATOM_AIRMONT (0x4c, Cherry Trail): 90C
> 
> - INTEL_ATOM_GOLDMONT (0x5c, Apollo Lake): 105C
> 
> - INTEL_ATOM_GOLDMONT_PLUS (0x7a, Gemini Lake): 105C
> 
> - INTEL_ATOM_TREMONT (0x96, Elkhart Lake): 105C
> 
> - INTEL_ATOM_TREMONT_L (0x9c, Jasper Lake): 105C
> 
> Not included (MSR reads work reliably, server/specialized chips):
> - INTEL_ATOM_SILVERMONT_D (Avoton): Server, Tcase 97C
> - INTEL_ATOM_GOLDMONT_D (Denverton): Server, Tcase 82C
> - INTEL_ATOM_AIRMONT_NP (Lightning Mountain): Network processor
> - INTEL_ATOM_TREMONT_D (Jacobsville): Server
> - INTEL_ATOM_GRACEMONT (Alder Lake-N): Very new, MSR works
> 
> Reference: Intel datasheets and ARK processor specifications
> - Z3600/Z3700 datasheet: https://www.intel.com/content/dam/www/public/us/en/documents/datasheets/atom-z36xxx-z37xxx-datasheet-vol-1.pdf
> - E3845 ARK: https://www.intel.com/content/www/us/en/products/sku/78475/intel-atom-processor-e3845-2m-cache-1-91-ghz/specifications.html
> - E3800 Spec Update: https://community.intel.com/cipcp26785/attachments/cipcp26785/embedded-atom-processors/4708/1/600834-329901-intel-atom-processor-e3800-product-family-su-rev015.pdf
> 
> Signed-off-by: Laveesh Bansal <laveeshb@laveeshbansal.com>

Applied.

Thanks,
Guenter