+++ /dev/null
-.. SPDX-License-Identifier: GPL-2.0
-
-============================================
-AMD HSMP interface
-============================================
-
-Newer Fam19h EPYC server line of processors from AMD support system
-management functionality via HSMP (Host System Management Port).
-
-The Host System Management Port (HSMP) is an interface to provide
-OS-level software with access to system management functions via a
-set of mailbox registers.
-
-More details on the interface can be found in chapter
-"7 Host System Management Port (HSMP)" of the family/model PPR
-Eg: https://www.amd.com/system/files/TechDocs/55898_B1_pub_0.50.zip
-
-HSMP interface is supported on EPYC server CPU models only.
-
-
-HSMP device
-============================================
-
-amd_hsmp driver under the drivers/platforms/x86/ creates miscdevice
-/dev/hsmp to let user space programs run hsmp mailbox commands.
-
-$ ls -al /dev/hsmp
-crw-r--r-- 1 root root 10, 123 Jan 21 21:41 /dev/hsmp
-
-Characteristics of the dev node:
- * Write mode is used for running set/configure commands
- * Read mode is used for running get/status monitor commands
-
-Access restrictions:
- * Only root user is allowed to open the file in write mode.
- * The file can be opened in read mode by all the users.
-
-In-kernel integration:
- * Other subsystems in the kernel can use the exported transport
- function hsmp_send_message().
- * Locking across callers is taken care by the driver.
-
-
-An example
-==========
-
-To access hsmp device from a C program.
-First, you need to include the headers::
-
- #include <linux/amd_hsmp.h>
-
-Which defines the supported messages/message IDs.
-
-Next thing, open the device file, as follows::
-
- int file;
-
- file = open("/dev/hsmp", O_RDWR);
- if (file < 0) {
- /* ERROR HANDLING; you can check errno to see what went wrong */
- exit(1);
- }
-
-The following IOCTL is defined:
-
-``ioctl(file, HSMP_IOCTL_CMD, struct hsmp_message *msg)``
- The argument is a pointer to a::
-
- struct hsmp_message {
- __u32 msg_id; /* Message ID */
- __u16 num_args; /* Number of input argument words in message */
- __u16 response_sz; /* Number of expected output/response words */
- __u32 args[HSMP_MAX_MSG_LEN]; /* argument/response buffer */
- __u16 sock_ind; /* socket number */
- };
-
-The ioctl would return a non-zero on failure; you can read errno to see
-what happened. The transaction returns 0 on success.
-
-More details on the interface and message definitions can be found in chapter
-"7 Host System Management Port (HSMP)" of the respective family/model PPR
-eg: https://www.amd.com/system/files/TechDocs/55898_B1_pub_0.50.zip
-
-User space C-APIs are made available by linking against the esmi library,
-which is provided by the E-SMS project https://developer.amd.com/e-sms/.
-See: https://github.com/amd/esmi_ib_library
git.samba.org / sfrench / cifs-2.6.git / blobdiff