- Provide user register access over IOCTL.
Both register read and write are supported.
- APML interface does not provide a synchronization method. By defining,
a register access path, we use APML modules and library for
all APML transactions. Without having to use external tools such as
i2c-tools, which may cause race conditions.
Reviewed-by: Naveen Krishna Chatradhi <naveenkrishna.chatradhi@amd.com>
Signed-off-by: Akshay Gupta <akshay.gupta@amd.com>
Link: https://lore.kernel.org/r/20250428063034.2145566-10-akshay.gupta@amd.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
- AMD provides custom protocol to read Machine Check Architecture(MCA)
registers over sideband. The information is accessed for range of
MCA registers by passing register address and thread ID to the protocol.
MCA register read command using the register address to access
Core::X86::Msr::MCG_CAP which determines the number of MCA banks.
Access is read-only
Reviewed-by: Naveen Krishna Chatradhi <naveenkrishna.chatradhi@amd.com>
Signed-off-by: Akshay Gupta <akshay.gupta@amd.com>
Link: https://lore.kernel.org/r/20250428063034.2145566-9-akshay.gupta@amd.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
- AMD provides custom protocol to read Processor feature
capabilities and configuration information through side band.
The information is accessed by providing CPUID Function,
extended function and thread ID to the protocol.
Undefined function returns 0.
Reviewed-by: Naveen Krishna Chatradhi <naveenkrishna.chatradhi@amd.com>
Signed-off-by: Akshay Gupta <akshay.gupta@amd.com>
Link: https://lore.kernel.org/r/20250428063034.2145566-8-akshay.gupta@amd.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The present sbrmi module only support reporting power via hwmon.
However, AMD data center range of processors support various
system management functionality using custom protocols defined in
Advanced Platform Management Link (APML) specification.
Register a miscdevice, which creates a device /dev/sbrmiX with an IOCTL
interface for the user space to invoke the APML Mailbox protocol, which
is already defined in sbrmi_mailbox_xfer().
The APML protocols depend on a set of RMI registers. Having an IOCTL
as a single entry point will help in providing synchronization among
these protocols as multiple transactions on RMI register set may
create race condition.
Support for other protocols will be added in subsequent patches.
APML mailbox protocol returns additional error codes written by
SMU firmware in the out-bound register 0x37. These errors include,
invalid core, message not supported over platform and
others. This additional error codes can be used to provide more
details to user space.
Open-sourced and widely used https://github.com/amd/esmi_oob_library
will continue to provide user-space programmable API.
Reviewed-by: Naveen Krishna Chatradhi <naveenkrishna.chatradhi@amd.com>
Signed-off-by: Akshay Gupta <akshay.gupta@amd.com>
Link: https://lore.kernel.org/r/20250428063034.2145566-7-akshay.gupta@amd.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
