From: Sandeep Singh <sandeep.singh@xxxxxxx> Add Maintainers for AMD SFH(SENSOR FUSION HUB) Solution and work flow document. Signed-off-by: Nehal Shah <Nehal-bakulchandra.Shah@xxxxxxx> Signed-off-by: Sandeep Singh <sandeep.singh@xxxxxxx> --- Documentation/hid/amd-sfh-hid.rst | 153 ++++++++++++++++++++++++++++++ MAINTAINERS | 8 ++ 2 files changed, 161 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 000000000000..0ee9003013f2 --- /dev/null +++ b/Documentation/hid/amd-sfh-hid.rst @@ -0,0 +1,153 @@ +.. 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 resembles ISH .However the major difference is all +The hid reports are generated as part of kernel driver. + +Block Diagram:- +============= + ------------------------------- + | HID User Space Applications | + ------------------------------- +--------------------------------------------- + --------------------------------- + | HID Core | + --------------------------------- + + --------------------------------- + | AMD HID Transport | + --------------------------------- + + -------------------------------- + | AMD HID Client | + | 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 synchronouscalls. + +AMD HID Client Layer:- +********************** +This layer is responsible to implement HID request and descriptors. As firmware is OS agnostic, +HID client layer fills the HID request structure and descriptors. HID client layer is in complex +in nature as it is interface between MP2 PCIe driver and HID. HID client layer 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 layer 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 layer 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 layer:- +******************** +MP2 PCIe Layer is responsible for making all transaction with the firmware over PCIe. +The connection establishment between firmware and PCIe 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 +3. Supported sensor info => P2C Register + +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 layer 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 layer layer 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| | | + | | | requested 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 d53db30d1365..fc6a712893fb 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -934,6 +934,14 @@ S: Supported F: arch/arm64/boot/dts/amd/amd-seattle-xgbe*.dtsi F: drivers/net/ethernet/amd/xgbe/ +AMD SENSOR FUSION HUB DRIVER +M: Nehal Shah <nehal-bakulchandra.shah@xxxxxxx> +M: Sandeep Singh <sandeep.singh@xxxxxxx> +L: linux-input@xxxxxxxxxxxxxxx +S: Maintained +F: Documentation/hid/amd-sfh* +F: drivers/hid/amd-sfh-hid/ + ANALOG DEVICES INC AD5686 DRIVER M: Michael Hennerich <Michael.Hennerich@xxxxxxxxxx> L: linux-pm@xxxxxxxxxxxxxxx -- 2.25.1
