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Make frequently fetched telemetry available via sysfs. These parameters do not fit in hwmon sensor model, hence make them available via sysfs. Create following sysfs files per acpi device node. * c0_residency_input * prochot_status * smu_fw_version * protocol_version * ddr_max_bw(GB/s) * ddr_utilised_bw_input(GB/s) * ddr_utilised_bw_perc_input(%) * mclk_input(MHz) * fclk_input(MHz) * clk_fmax(MHz) * clk_fmin(MHz) * cclk_freq_limit_input(MHz) * pwr_current_active_freq_limit(MHz) * pwr_current_active_freq_limit_source Signed-off-by: Suma Hegde <suma.hegde@amd.com> Reviewed-by: Naveen Krishna Chatradhi <naveenkrishna.chatradhi@amd.com> Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com> Link: https://lore.kernel.org/r/20250506101542.200811-3-suma.hegde@amd.com Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
192 lines
6.1 KiB
ReStructuredText
192 lines
6.1 KiB
ReStructuredText
.. SPDX-License-Identifier: GPL-2.0
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============================================
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AMD HSMP interface
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============================================
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Newer Fam19h(model 0x00-0x1f, 0x30-0x3f, 0x90-0x9f, 0xa0-0xaf),
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Fam1Ah(model 0x00-0x1f) EPYC server line of processors from AMD support
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system management functionality via HSMP (Host System Management Port).
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The Host System Management Port (HSMP) is an interface to provide
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OS-level software with access to system management functions via a
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set of mailbox registers.
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More details on the interface can be found in chapter
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"7 Host System Management Port (HSMP)" of the family/model PPR
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Eg: https://www.amd.com/content/dam/amd/en/documents/epyc-technical-docs/programmer-references/55898_B1_pub_0_50.zip
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HSMP interface is supported on EPYC line of server CPUs and MI300A (APU).
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HSMP device
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============================================
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amd_hsmp driver under drivers/platforms/x86/amd/hsmp/ has separate driver files
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for ACPI object based probing, platform device based probing and for the common
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code for these two drivers.
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Kconfig option CONFIG_AMD_HSMP_PLAT compiles plat.c and creates amd_hsmp.ko.
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Kconfig option CONFIG_AMD_HSMP_ACPI compiles acpi.c and creates hsmp_acpi.ko.
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Selecting any of these two configs automatically selects CONFIG_AMD_HSMP. This
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compiles common code hsmp.c and creates hsmp_common.ko module.
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Both the ACPI and plat drivers create the miscdevice /dev/hsmp to let
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user space programs run hsmp mailbox commands.
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The ACPI object format supported by the driver is defined below.
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$ ls -al /dev/hsmp
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crw-r--r-- 1 root root 10, 123 Jan 21 21:41 /dev/hsmp
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Characteristics of the dev node:
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* Write mode is used for running set/configure commands
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* Read mode is used for running get/status monitor commands
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Access restrictions:
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* Only root user is allowed to open the file in write mode.
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* The file can be opened in read mode by all the users.
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In-kernel integration:
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* Other subsystems in the kernel can use the exported transport
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function hsmp_send_message().
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* Locking across callers is taken care by the driver.
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HSMP sysfs interface
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====================
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1. Metrics table binary sysfs
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AMD MI300A MCM provides GET_METRICS_TABLE message to retrieve
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most of the system management information from SMU in one go.
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The metrics table is made available as hexadecimal sysfs binary file
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under per socket sysfs directory created at
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/sys/devices/platform/amd_hsmp/socket%d/metrics_bin
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Note: lseek() is not supported as entire metrics table is read.
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Metrics table definitions will be documented as part of Public PPR.
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The same is defined in the amd_hsmp.h header.
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2. HSMP telemetry sysfs files
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Following sysfs files are available at /sys/devices/platform/AMDI0097:0X/.
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* c0_residency_input: Percentage of cores in C0 state.
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* prochot_status: Reports 1 if the processor is at thermal threshold value,
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0 otherwise.
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* smu_fw_version: SMU firmware version.
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* protocol_version: HSMP interface version.
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* ddr_max_bw: Theoretical maximum DDR bandwidth in GB/s.
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* ddr_utilised_bw_input: Current utilized DDR bandwidth in GB/s.
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* ddr_utilised_bw_perc_input(%): Percentage of current utilized DDR bandwidth.
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* mclk_input: Memory clock in MHz.
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* fclk_input: Fabric clock in MHz.
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* clk_fmax: Maximum frequency of socket in MHz.
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* clk_fmin: Minimum frequency of socket in MHz.
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* cclk_freq_limit_input: Core clock frequency limit per socket in MHz.
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* pwr_current_active_freq_limit: Current active frequency limit of socket
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in MHz.
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* pwr_current_active_freq_limit_source: Source of current active frequency
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limit.
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ACPI device object format
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=========================
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The ACPI object format expected from the amd_hsmp driver
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for socket with ID00 is given below::
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Device(HSMP)
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{
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Name(_HID, "AMDI0097")
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Name(_UID, "ID00")
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Name(HSE0, 0x00000001)
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Name(RBF0, ResourceTemplate()
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{
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Memory32Fixed(ReadWrite, 0xxxxxxx, 0x00100000)
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})
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Method(_CRS, 0, NotSerialized)
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{
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Return(RBF0)
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}
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Method(_STA, 0, NotSerialized)
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{
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If(LEqual(HSE0, One))
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{
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Return(0x0F)
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}
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Else
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{
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Return(Zero)
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}
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}
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Name(_DSD, Package(2)
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{
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Buffer(0x10)
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{
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0x9D, 0x61, 0x4D, 0xB7, 0x07, 0x57, 0xBD, 0x48,
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0xA6, 0x9F, 0x4E, 0xA2, 0x87, 0x1F, 0xC2, 0xF6
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},
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Package(3)
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{
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Package(2) {"MsgIdOffset", 0x00010934},
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Package(2) {"MsgRspOffset", 0x00010980},
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Package(2) {"MsgArgOffset", 0x000109E0}
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}
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})
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}
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HSMP HWMON interface
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====================
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HSMP power sensors are registered with the hwmon interface. A separate hwmon
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directory is created for each socket and the following files are generated
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within the hwmon directory.
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- power1_input (read only)
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- power1_cap_max (read only)
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- power1_cap (read, write)
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An example
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==========
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To access hsmp device from a C program.
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First, you need to include the headers::
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#include <linux/amd_hsmp.h>
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Which defines the supported messages/message IDs.
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Next thing, open the device file, as follows::
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int file;
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file = open("/dev/hsmp", O_RDWR);
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if (file < 0) {
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/* ERROR HANDLING; you can check errno to see what went wrong */
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exit(1);
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}
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The following IOCTL is defined:
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``ioctl(file, HSMP_IOCTL_CMD, struct hsmp_message *msg)``
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The argument is a pointer to a::
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struct hsmp_message {
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__u32 msg_id; /* Message ID */
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__u16 num_args; /* Number of input argument words in message */
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__u16 response_sz; /* Number of expected output/response words */
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__u32 args[HSMP_MAX_MSG_LEN]; /* argument/response buffer */
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__u16 sock_ind; /* socket number */
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};
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The ioctl would return a non-zero on failure; you can read errno to see
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what happened. The transaction returns 0 on success.
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More details on the interface and message definitions can be found in chapter
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"7 Host System Management Port (HSMP)" of the respective family/model PPR
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eg: https://www.amd.com/content/dam/amd/en/documents/epyc-technical-docs/programmer-references/55898_B1_pub_0_50.zip
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User space C-APIs are made available by linking against the esmi library,
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which is provided by the E-SMS project https://www.amd.com/en/developer/e-sms.html.
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See: https://github.com/amd/esmi_ib_library
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