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1.. SPDX-License-Identifier: GPL-2.02 3======================================4UltraSoc - HW Assisted Tracing on SoC5======================================6 :Author: Qi Liu <liuqi115@huawei.com>7 :Date: January 20238 9Introduction10------------11 12UltraSoc SMB is a per SCCL (Super CPU Cluster) hardware. It provides a13way to buffer and store CPU trace messages in a region of shared system14memory. The device acts as a coresight sink device and the15corresponding trace generators (ETM) are attached as source devices.16 17Sysfs files and directories18---------------------------19 20The SMB devices appear on the existing coresight bus alongside other21devices::22 23 $# ls /sys/bus/coresight/devices/24 ultra_smb0 ultra_smb1 ultra_smb2 ultra_smb325 26The ``ultra_smb<N>`` names SMB device associated with SCCL.::27 28 $# ls /sys/bus/coresight/devices/ultra_smb029 enable_sink mgmt30 $# ls /sys/bus/coresight/devices/ultra_smb0/mgmt31 buf_size buf_status read_pos write_pos32 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 Bindings42-----------------43 44The device is only supported with ACPI. Its binding describes device45identifier, resource information and graph structure.46 47The device is identified as ACPI HID "HISI03A1". Device resources are allocated48using the _CRS method. Each device must present two base address; the first one49is the configuration base address of the device, the second one is the 32-bit50base 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