From: Sandeep Singh Add Maintainers for AMD SFH(SENSOR FUSION HUB) Solution and work flow document. Signed-off-by: Sandeep Singh Signed-off-by: Nehal Shah --- Documentation/hid/amd-sfh-hid.rst | 160 ++++++++++++++++++++++++++++++++++++++ MAINTAINERS | 8 ++ 2 files changed, 168 insertions(+) create mode 100644 Documentation/hid/amd-sfh-hid.rst diff --git a/Documentation/hid/amd-sfh-hid.rst b/Documentation/hid/amd-sfh-hid.rst new file mode 100644 index 0000000..eb60ac1 --- /dev/null +++ b/Documentation/hid/amd-sfh-hid.rst @@ -0,0 +1,160 @@ +.. SPDX-License-Identifier: GPL-2.0 + +AMD Sensor Fusion Hub:- +====================== +AMD Sensor Fusion Hub is part of a SOC starting from Ryzen based platforms. +The solution is working well on several OEM products. AMD +SFH uses HID over PCIe bus. In terms of architecture +it is much more resembles like ISH .However the major diffrence is all +The hid reports are generated as part of kernel driver. + +Block Diagram:- +============= + ------------------------------- + | HID User Space Applications | + ------------------------------- +--------------------------------------------- + --------------------------------- + | HID Core | + --------------------------------- + + --------------------------------- + | AMD HID Transport Driver | + --------------------------------- + + -------------------------------- + | AMD HID Client Driver | + | with HID Report Generator| + -------------------------------- + + -------------------------------- + | AMD MP2 PCIe Driver | + -------------------------------- +--------------------------------------------- + ------------------------------- + | SFH MP2 Processor | + -------------------------------- + + +AMD HID Transport Layer :- +*************************** +AMD SFH transport is also implemented as a bus. Each client application +executing in the AMD MP2 is registered as a device on this bus. +MP2 which is an ARM® Cortex-M4 core based co-processor to x86. +The driver, which binds each device (AMD SFH HID driver) identifies +the device type and registers with the hid core. Transport drivers +attach a constant "struct hid_ll_driver" object with each device. +Once a device is registered with HID core, the callbacks provided via +this struct are used by HID core to communicate with the device. +AMD HID Transport driver implements the synchronous calls. + +AMD HID Client Driver:- +********************** +This driver is responsible to implement HID request and descriptors. +As firmware is OS agnostic, HID client driver fills the HID request +structure and descriptors. HID client driver is in complex in nature +as it is interface between MP2 PCIe driver and HID. HID client driver +initialized the MP2 PCIe driver and holds the instance of MP2 driver. +It identified the number of sensors connected using MP2-PCIe driver and +based on that allocate the DRAM address for each and every sensor and +pass it to MP2-PCIe driver. +On enumeration of each sensor, client driver fills out the HID Descriptor +structure and HID input report structure. HID Feature report structure can +be optional. The report descriptor structure varies sensor to sensor. +Now on enumeration client driver does two major things +1. Register the HID sensor client to virtual bus (Platform driver) and bind it. +2. Probes the AMD HID transport driver. Which in turns register device to the core. + +AMD MP2 PCIe Driver:- +******************** +MP2 PCIe driver is responsible for making all transaction with the firmware over +PCIe.The connection establishment between firmware and MP2 PCIe driver happens here. + +The communication between X86 and MP2 is spilt into three parts. +1. Command Transfer => C2P Mailbox Register are used +2. Data Transfer => DRAM + +Commands are sent to MP2 using C2P Mail Box registers. These C2P registers +are common between x86 and MP2. Writing into C2P Message register generate +interrupt to MP2. The client driver allocates the physical memory and send +the same to MP2 for data transfer. MP2 firmware uses HUBIF interface +to access DRAM memory. For Firmware always write minimum 32 bytes +into DRAM.So it is expected that driver shall allocate minimum 32 bytes DRAM space. + +Enumeration and Probing flow:- +***************************** + HID AMD AMD AMD -PCIe MP2 + Core Transport Client Driver Driver FW + | | | | | + | | on Boot Driver Loaded | | + | | | | | + | | |----MP2-PCIe Int---------> | | + | | | | | + | | |---Get Number of sensors-> | | + | | | Read P2C | + | | | Register | + | | | | | + | | | Loop(for No of Sensors) | | + | | |----------------------| | | + | | | Create HID Descriptor| | | + | | | Create Input report | | | + | | | Descriptor Map | | | + | | | the MP2 FW Index to | | | + | | | HID Index | | | + | | | Allocate the DRAM | Enable | + | | | address | Sensors | + | | |----------------------| | | + | | HID transport| | Enable | + | |<--Probe------| |---Sensor CMD--> | + | | Create the | | | + | | HID device | | | + | | (MFD) | | | + | | by Populating| | | + | | the HID | | | + | | ll_driver | | | + | HID | | | | + | add | | | | + |Device | | | | + |<------------- | | | | + + +Data Flow from Application to the AMD SFH Driver:- +************************************************* + + | | | | | +Get | | | | | +Input | | | | | +Report | | | | | +---> | | | | | + |HID_req | | | | + |get_report | | | | + |------------->| | | | + | | HID_get_input| | | + | | report | | | + | |------------->|------------------------| | | + | | | Read the DRAM data for| | | + | | | requsted sensor and | | | + | | | create the HID input | | | + | | | report | | | + | | |------------------------| | | + | |Data received | | | + | | in HID report| | | + To |<-------------|<-------------| | | +Applications | | | | +<-------| | | | | + + +Data Flow from AMD SFH Driver to Application:- +********************************************** + | | | | | + | | |------------------------| | | + | | |Periodically Read | | | + | | |the data for all | | | + | | |enumerated sensors | | | + | | |from the dram and create| | | + | | | HID Input reports | | | + | | |------------------------| | | + | |HID Input | | | + | |Input report | | | + <----submit to Application-----| | | + | | | | | diff --git a/MAINTAINERS b/MAINTAINERS index 56765f5..7cfeb5a 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -884,6 +884,14 @@ S: Supported F: drivers/net/ethernet/amd/xgbe/ F: arch/arm64/boot/dts/amd/amd-seattle-xgbe*.dtsi +AMD SENSOR FUSION HUB DRIVER +M: Nehal Shah +M: Sandeep Singh +L: linux-input@vger.kernel.org +S: Maintained +F: Documentation/hid/amd-sfh* +F: drivers/hid/amd-sfh-hid/ + ANALOG DEVICES INC AD5686 DRIVER M: Stefan Popa L: linux-pm@vger.kernel.org -- 2.7.4