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authorLinus Torvalds <torvalds@linux-foundation.org>2022-03-25 22:14:39 +0300
committerLinus Torvalds <torvalds@linux-foundation.org>2022-03-25 22:14:39 +0300
commit1464677662943738741500a6f16b85d36bbde2be (patch)
tree316d8a47d4cc6d2f579cbed80e2f977a0aed64ed /Documentation/x86
parent50560ce6a0bdab2fc37384c52aa02c7043909d2c (diff)
parentb49f72e7f96d4ed147447428f2ae5b4cea598ca7 (diff)
downloadlinux-1464677662943738741500a6f16b85d36bbde2be.tar.xz
Merge tag 'platform-drivers-x86-v5.18-1' of git://git.kernel.org/pub/scm/linux/kernel/git/pdx86/platform-drivers-x86
Pull x86 platform driver updates from Hans de Goede: "New drivers: - AMD Host System Management Port (HSMP) - Intel Software Defined Silicon Removed drivers (functionality folded into other drivers): - intel_cht_int33fe_microb - surface3_button amd-pmc: - s2idle bug-fixes - Support for AMD Spill to DRAM STB feature hp-wmi: - Fix SW_TABLET_MODE detection method (and other fixes) - Support omen thermal profile policy v1 serial-multi-instantiate: - Add SPI device support - Add support for CS35L41 amplifiers used in new laptops think-lmi: - syfs-class-firmware-attributes Certificate authentication support thinkpad_acpi: - Fixes + quirks - Add platform_profile support on AMD based ThinkPads x86-android-tablets: - Improve Asus ME176C / TF103C support - Support Nextbook Ares 8, Lenovo Tab 2 830 and 1050 tablets Lots of various other small fixes and hardware-id additions" * tag 'platform-drivers-x86-v5.18-1' of git://git.kernel.org/pub/scm/linux/kernel/git/pdx86/platform-drivers-x86: (60 commits) platform/x86: think-lmi: Certificate authentication support Documentation: syfs-class-firmware-attributes: Lenovo Certificate support platform/x86: amd-pmc: Only report STB errors when STB enabled platform/x86: amd-pmc: Drop CPU QoS workaround platform/x86: amd-pmc: Output error codes in messages platform/x86: amd-pmc: Move to later in the suspend process ACPI / x86: Add support for LPS0 callback handler platform/x86: thinkpad_acpi: consistently check fan_get_status return. platform/x86: hp-wmi: support omen thermal profile policy v1 platform/x86: hp-wmi: Changing bios_args.data to be dynamically allocated platform/x86: hp-wmi: Fix 0x05 error code reported by several WMI calls platform/x86: hp-wmi: Fix SW_TABLET_MODE detection method platform/x86: hp-wmi: Fix hp_wmi_read_int() reporting error (0x05) platform/x86: amd-pmc: Validate entry into the deepest state on resume platform/x86: thinkpad_acpi: Don't use test_bit on an integer platform/x86: thinkpad_acpi: Fix compiler warning about uninitialized err variable platform/x86: thinkpad_acpi: clean up dytc profile convert platform/x86: x86-android-tablets: Depend on EFI and SPI platform/x86: amd-pmc: uninitialized variable in amd_pmc_s2d_init() platform/x86: intel-uncore-freq: fix uncore_freq_common_init() error codes ...
Diffstat (limited to 'Documentation/x86')
-rw-r--r--Documentation/x86/amd_hsmp.rst86
-rw-r--r--Documentation/x86/index.rst1
2 files changed, 87 insertions, 0 deletions
diff --git a/Documentation/x86/amd_hsmp.rst b/Documentation/x86/amd_hsmp.rst
new file mode 100644
index 000000000000..440e4b645a1c
--- /dev/null
+++ b/Documentation/x86/amd_hsmp.rst
@@ -0,0 +1,86 @@
+.. 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
diff --git a/Documentation/x86/index.rst b/Documentation/x86/index.rst
index 982c8af853b9..91b2fa456618 100644
--- a/Documentation/x86/index.rst
+++ b/Documentation/x86/index.rst
@@ -25,6 +25,7 @@ x86-specific Documentation
intel-iommu
intel_txt
amd-memory-encryption
+ amd_hsmp
pti
mds
microcode