projects / linux-block.git / blame
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1 | .. SPDX-License-Identifier: GPL-2.0 |
| 2 | ||
| 3 | ||
| 4 | AMD Sensor Fusion Hub | |
| 5 | ===================== | |
| 4acdc5e5 | 6 | AMD Sensor Fusion Hub (SFH) is part of an SOC starting from Ryzen-based platforms. |
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7 | The solution is working well on several OEM products. AMD SFH uses HID over PCIe bus. |
| 8 | In terms of architecture it resembles ISH, however the major difference is all | |
| 9 | the HID reports are generated as part of the kernel driver. | |
| 10 | ||
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11 | Block Diagram |
| 12 | ------------- | |
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13 | |
| 14 | :: | |
| 15 | ||
| 16 | --------------------------------- | |
| 17 | | HID User Space Applications | | |
| 18 | - ------------------------------- | |
| 19 | ||
| 20 | --------------------------------------------- | |
| 21 | --------------------------------- | |
| 22 | | HID Core | | |
| 23 | --------------------------------- | |
| 24 | ||
| 25 | --------------------------------- | |
| 26 | | AMD HID Transport | | |
| 27 | --------------------------------- | |
| 28 | ||
| 29 | -------------------------------- | |
| 30 | | AMD HID Client | | |
| 31 | | with HID Report Generator| | |
| 32 | -------------------------------- | |
| 33 | ||
| 34 | -------------------------------- | |
| 35 | | AMD MP2 PCIe Driver | | |
| 36 | -------------------------------- | |
| 37 | OS | |
| 38 | --------------------------------------------- | |
| 39 | Hardware + Firmware | |
| 40 | -------------------------------- | |
| 41 | | SFH MP2 Processor | | |
| 42 | -------------------------------- | |
| 43 | ||
| 44 | ||
| 45 | AMD HID Transport Layer | |
| 46 | ----------------------- | |
| 47 | AMD SFH transport is also implemented as a bus. Each client application executing in the AMD MP2 is | |
| 4acdc5e5 | 48 | registered as a device on this bus. Here, MP2 is an ARM core connected to x86 for processing |
| 907286d1 | 49 | sensor data. The layer, which binds each device (AMD SFH HID driver) identifies the device type and |
| 4acdc5e5 | 50 | registers with the HID core. Transport layer attaches a constant "struct hid_ll_driver" object with |
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51 | each device. Once a device is registered with HID core, the callbacks provided via this struct are |
| 52 | used by HID core to communicate with the device. AMD HID Transport layer implements the synchronous calls. | |
| 53 | ||
| 54 | AMD HID Client Layer | |
| 55 | -------------------- | |
| 4acdc5e5 | 56 | This layer is responsible to implement HID requests and descriptors. As firmware is OS agnostic, HID |
| 907286d1 | 57 | client layer fills the HID request structure and descriptors. HID client layer is complex as it is |
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58 | interface between MP2 PCIe layer and HID. HID client layer initializes the MP2 PCIe layer and holds |
| 59 | the instance of MP2 layer. It identifies the number of sensors connected using MP2-PCIe layer. Based | |
| 60 | on that allocates the DRAM address for each and every sensor and passes it to MP2-PCIe driver. On | |
| 61 | enumeration of each sensor, client layer fills the HID Descriptor structure and HID input report | |
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62 | structure. HID Feature report structure is optional. The report descriptor structure varies from |
| 63 | sensor to sensor. | |
| 64 | ||
| 65 | AMD MP2 PCIe layer | |
| 66 | ------------------ | |
| 67 | MP2 PCIe Layer is responsible for making all transactions with the firmware over PCIe. | |
| 68 | The connection establishment between firmware and PCIe happens here. | |
| 69 | ||
| 70 | The communication between X86 and MP2 is split into three parts. | |
| 71 | 1. Command transfer via the C2P mailbox registers. | |
| 72 | 2. Data transfer via DRAM. | |
| 73 | 3. Supported sensor info via P2C registers. | |
| 74 | ||
| 4acdc5e5 | 75 | Commands are sent to MP2 using C2P Mailbox registers. Writing into C2P Message registers generates |
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76 | interrupt to MP2. The client layer allocates the physical memory and the same is sent to MP2 via |
| 77 | the PCI layer. MP2 firmware writes the command output to the access DRAM memory which the client | |
| 78 | layer has allocated. Firmware always writes minimum of 32 bytes into DRAM. So as a protocol driver | |
| 79 | shall allocate minimum of 32 bytes DRAM space. | |
| 80 | ||
| 81 | Enumeration and Probing flow | |
| 82 | ---------------------------- | |
| 83 | :: | |
| 84 | ||
| 85 | HID AMD AMD AMD -PCIe MP2 | |
| 86 | Core Transport Client layer layer FW | |
| 87 | | | | | | | |
| 88 | | | | on Boot Driver Loaded | | |
| 89 | | | | | | | |
| 90 | | | | MP2-PCIe Int | | |
| 91 | | | | | | | |
| 92 | | | |---Get Number of sensors-> | | | |
| 93 | | | | Read P2C | | |
| 94 | | | | Register | | |
| 95 | | | | | | | |
| 96 | | | | Loop(for No of Sensors) | | | |
| 97 | | | |----------------------| | | | |
| 98 | | | | Create HID Descriptor| | | | |
| 99 | | | | Create Input report | | | | |
| 100 | | | | Descriptor Map | | | | |
| 101 | | | | the MP2 FW Index to | | | | |
| 102 | | | | HID Index | | | | |
| 103 | | | | Allocate the DRAM | Enable | | |
| 104 | | | | address | Sensors | | |
| 105 | | | |----------------------| | | | |
| 106 | | | HID transport| | Enable | | |
| 107 | | |<--Probe------| |---Sensor CMD--> | | |
| 108 | | | Create the | | | | |
| 109 | | | HID device | | | | |
| 110 | | | (MFD) | | | | |
| 111 | | | by Populating| | | | |
| 112 | | | the HID | | | | |
| 113 | | | ll_driver | | | | |
| 114 | | HID | | | | | |
| 115 | | add | | | | | |
| 116 | |Device | | | | | |
| 117 | |<------------- | | | | | |
| 118 | ||
| 119 | ||
| 120 | Data Flow from Application to the AMD SFH Driver | |
| 121 | ------------------------------------------------ | |
| 122 | ||
| 123 | :: | |
| 124 | ||
| 125 | | | | | | | |
| 126 | | | | | | | |
| 127 | | | | | | | |
| 128 | | | | | | | |
| 129 | | | | | | | |
| 130 | |HID_req | | | | | |
| 131 | |get_report | | | | | |
| 132 | |------------->| | | | | |
| 133 | | | HID_get_input| | | | |
| 134 | | | report | | | | |
| 135 | | |------------->|------------------------| | | | |
| 136 | | | | Read the DRAM data for| | | | |
| 137 | | | | requested sensor and | | | | |
| 138 | | | | create the HID input | | | | |
| 139 | | | | report | | | | |
| 140 | | | |------------------------| | | | |
| 141 | | |Data received | | | | |
| 142 | | | in HID report| | | | |
| 143 | To |<-------------|<-------------| | | | |
| 144 | Applications| | | | | | |
| 145 | <-------| | | | | |