From: Prathima <Prathima.Lk@amd.com>

- Document AMD sideband IOCTL description defined
  for SBTSI and its usage.
  User space C-APIs are made available by esmi_oob_library [1],
  which is provided by the E-SMS project [2].

  Link: https://github.com/amd/esmi_oob_library [1]
  Link: https://www.amd.com/en/developer/e-sms.html [2]

Reviewed-by: Akshay Gupta <Akshay.Gupta@amd.com>
Signed-off-by: Prathima <Prathima.Lk@amd.com>
---
 Documentation/misc-devices/amd-sbi.rst | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/Documentation/misc-devices/amd-sbi.rst b/Documentation/misc-devices/amd-sbi.rst
index f91ddadefe48..ddff3cea8ed1 100644
--- a/Documentation/misc-devices/amd-sbi.rst
+++ b/Documentation/misc-devices/amd-sbi.rst
@@ -48,6 +48,20 @@ Access restrictions:
  * APML Mailbox messages and Register xfer access are read-write,
  * CPUID and MCA_MSR access is read-only.
 
+SBTSI device
+============
+
+apml_sbtsi driver under the drivers/misc/amd-sbi creates miscdevice
+/dev/sbtsi-* to let user space programs run APML TSI register xfer
+commands.
+
+The driver supports both I2C and I3C transports for SB-TSI targets.
+The transport is selected by the bus where the device is enumerated.
+
+Access restrictions:
+ * Only root user is allowed to open the file.
+ * APML TSI Register xfer access is read-write.
+
 Driver IOCTLs
 =============
 
@@ -63,6 +77,9 @@ Driver IOCTLs
 .. c:macro:: SBRMI_IOCTL_REG_XFER_CMD
 .. kernel-doc:: include/uapi/misc/amd-apml.h
    :doc: SBRMI_IOCTL_REG_XFER_CMD
+.. c:macro:: SBTSI_IOCTL_REG_XFER_CMD
+.. kernel-doc:: include/uapi/misc/amd-apml.h
+   :doc: SBTSI_IOCTL_REG_XFER_CMD
 
 User-space usage
 ================
@@ -92,6 +109,7 @@ The following IOCTLs are defined:
 ``#define SBRMI_IOCTL_CPUID_CMD		_IOWR(SB_BASE_IOCTL_NR, 1, struct apml_cpuid_msg)``
 ``#define SBRMI_IOCTL_MCAMSR_CMD	_IOWR(SB_BASE_IOCTL_NR, 2, struct apml_mcamsr_msg)``
 ``#define SBRMI_IOCTL_REG_XFER_CMD	_IOWR(SB_BASE_IOCTL_NR, 3, struct apml_reg_xfer_msg)``
+``#define SBTSI_IOCTL_REG_XFER_CMD      _IOWR(SB_BASE_IOCTL_NR, 4, struct apml_tsi_xfer_msg)``
 
 
 User space C-APIs are made available by esmi_oob_library, hosted at
-- 
2.34.1

On Mon, Mar 23, 2026 at 04:38:11PM +0530, Akshay Gupta wrote:
> From: Prathima <Prathima.Lk@amd.com>
> 
> - Document AMD sideband IOCTL description defined
>   for SBTSI and its usage.
>   User space C-APIs are made available by esmi_oob_library [1],
>   which is provided by the E-SMS project [2].
> 
>   Link: https://github.com/amd/esmi_oob_library [1]
>   Link: https://www.amd.com/en/developer/e-sms.html [2]

Ok, nevermind, here's the documentation :)

But it's very tiny, it's not saying what the api actually is.

thanks,

greg k-h

On 3/27/2026 12:55 PM, Greg KH wrote:
> Caution: This message originated from an External Source. Use proper caution when opening attachments, clicking links, or responding.
>
>
> On Mon, Mar 23, 2026 at 04:38:11PM +0530, Akshay Gupta wrote:
>> From: Prathima <Prathima.Lk@amd.com>
>>
>> - Document AMD sideband IOCTL description defined
>>    for SBTSI and its usage.
>>    User space C-APIs are made available by esmi_oob_library [1],
>>    which is provided by the E-SMS project [2].
>>
>>    Link: https://github.com/amd/esmi_oob_library [1]
>>    Link: https://www.amd.com/en/developer/e-sms.html [2]
> Ok, nevermind, here's the documentation :)
>
> But it's very tiny, it's not saying what the api actually is.
>
> thanks,
>
> greg k-h

Hi Greg,

Thank you for the feedback, will update the doc in next version with 
details.