1.. SPDX-License-Identifier: GPL-2.0 2 3====================================== 4UltraSoc - HW Assisted Tracing on SoC 5====================================== 6 :Author: Qi Liu <liuqi115@huawei.com> 7 :Date: January 2023 8 9Introduction 10------------ 11 12UltraSoc SMB is a per SCCL (Super CPU Cluster) hardware. It provides a 13way to buffer and store CPU trace messages in a region of shared system 14memory. The device acts as a coresight sink device and the 15corresponding trace generators (ETM) are attached as source devices. 16 17Sysfs files and directories 18--------------------------- 19 20The SMB devices appear on the existing coresight bus alongside other 21devices:: 22 23 $# ls /sys/bus/coresight/devices/ 24 ultra_smb0 ultra_smb1 ultra_smb2 ultra_smb3 25 26The ``ultra_smb<N>`` names SMB device associated with SCCL.:: 27 28 $# ls /sys/bus/coresight/devices/ultra_smb0 29 enable_sink mgmt 30 $# ls /sys/bus/coresight/devices/ultra_smb0/mgmt 31 buf_size buf_status read_pos write_pos 32 33Key file items are: 34 35 * ``read_pos``: Shows the value on the read pointer register. 36 * ``write_pos``: Shows the value on the write pointer register. 37 * ``buf_status``: Shows the value on the status register. 38 BIT(0) is zero value which means the buffer is empty. 39 * ``buf_size``: Shows the buffer size of each device. 40 41Firmware Bindings 42----------------- 43 44The device is only supported with ACPI. Its binding describes device 45identifier, resource information and graph structure. 46 47The device is identified as ACPI HID "HISI03A1". Device resources are allocated 48using the _CRS method. Each device must present two base address; the first one 49is the configuration base address of the device, the second one is the 32-bit 50base address of shared system memory. 51 52Example:: 53 54 Device(USMB) { \ 55 Name(_HID, "HISI03A1") \ 56 Name(_CRS, ResourceTemplate() { \ 57 QWordMemory (ResourceConsumer, , MinFixed, MaxFixed, NonCacheable, \ 58 ReadWrite, 0x0, 0x95100000, 0x951FFFFF, 0x0, 0x100000) \ 59 QWordMemory (ResourceConsumer, , MinFixed, MaxFixed, Cacheable, \ 60 ReadWrite, 0x0, 0x50000000, 0x53FFFFFF, 0x0, 0x4000000) \ 61 }) \ 62 Name(_DSD, Package() { \ 63 ToUUID("ab02a46b-74c7-45a2-bd68-f7d344ef2153"), \ 64 /* Use CoreSight Graph ACPI bindings to describe connections topology */ 65 Package() { \ 66 0, \ 67 1, \ 68 Package() { \ 69 1, \ 70 ToUUID("3ecbc8b6-1d0e-4fb3-8107-e627f805c6cd"), \ 71 8, \ 72 Package() {0x8, 0, \_SB.S00.SL11.CL28.F008, 0}, \ 73 Package() {0x9, 0, \_SB.S00.SL11.CL29.F009, 0}, \ 74 Package() {0xa, 0, \_SB.S00.SL11.CL2A.F010, 0}, \ 75 Package() {0xb, 0, \_SB.S00.SL11.CL2B.F011, 0}, \ 76 Package() {0xc, 0, \_SB.S00.SL11.CL2C.F012, 0}, \ 77 Package() {0xd, 0, \_SB.S00.SL11.CL2D.F013, 0}, \ 78 Package() {0xe, 0, \_SB.S00.SL11.CL2E.F014, 0}, \ 79 Package() {0xf, 0, \_SB.S00.SL11.CL2F.F015, 0}, \ 80 } \ 81 } \ 82 }) \ 83 } 84