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diff --git a/Documentation/x86/amd_hsmp.rst b/Documentation/x86/amd_hsmp.rst deleted file mode 100644 index 440e4b645a1c..000000000000 --- a/Documentation/x86/amd_hsmp.rst +++ /dev/null @@ -1,86 +0,0 @@ -.. 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 |