This version (15 Nov 2023 11:39) was approved by Michael Hennerich.The Previously approved version (08 Apr 2022 15:17) is available.
Table of Contents
ADI JESD204B/C Receive Peripheral Linux Driver
Supported Devices
Description
The AXI JESD204B RX peripheral driver is a simple driver that supports the ADI JESD204B Receive Peripheral. The driver reads JESD204B link configuration data from the devicetree and configures the peripheral accordingly. After configuration has completed the JESD204B link is enabled. Link state can be monitored through sysfs files.
This driver also work in conjunction with the JESD204 (FSM) Interface Linux Kernel Framework, in this case JESD204B link configuration is provided by the JESD204-FSM framework.
Source Code
Status
| Source | Mainlined? |
|---|---|
| drivers/iio/jesd204/axi_jesd204_rx.c | No |
Files
| Function | File |
|---|---|
| driver | drivers/iio/jesd204/axi_jesd204_rx.c |
Example platform device / device tree initialization
The AXI JESD204B driver is a platform driver and can currently only be instantiated via device tree.
Deprecated Non-jesd204-fsm mode
Required devicetree properties:
- compatible: Must always be “adi,axi-jesd204-rx-1.00.a”
- reg: Base address and register area size. This parameter expects a register range.
- interrupts: Property with a value describing the interrupt number.
- clock-names: List of input clock names - “s_axi_aclk”, “device_clk”
- clocks: Clock phandles and specifiers (See clock bindings for details on clock-names and clocks).
- adi,frames-per-multiframe: Number of frames per multi-frame (
K) - adi,octets-per-frame: Number of octets per frame (
F)
Optional devicetree properties:
- adi,high-density: If specified the JESD204B link is configured for high density (
HD) operation. - adi,subclass: The JESD204B subclass.
Example:
jesd204b-rx@77b00000 {
compatible = "adi,axi-jesd204-rx-1.00.a";
reg = <0x77b00000 0x10000>;
interrupts = <0 56 4>;
clock-names = "s_axi_aclk", "device_clk";
clocks = <&clkc 14>, <&ad9528 13>;
adi,octets-per-frame = <32>;
adi,frames-per-multiframe = <4>;
};
jesd204-fsm mode
When using the JESD204 (FSM) Interface Linux Kernel Framework the JESD link parameters are broadcasted by the framework to all link components.
Required devicetree properties:
- compatible: Must always be “adi,axi-jesd204-rx-1.00.a”
- reg: Base address and register area size. This parameter expects a register range.
- interrupts: Property with a value describing the interrupt number.
- clock-names: List of input clock names - “s_axi_aclk”, “device_clk”, “lane_clk”
- clocks: Clock phandles and specifiers (See clock bindings for details on clock-names and clocks).
- jesd204-device: Adds device to the jesd204-fsm kernel framework
- jesd204-inputs: jesd204-fsm devices phandles and specifiers (used to build the link topology)
Optional devicetree clock-names:
- link_clk: When using the link layer gearbox in order to support NP=12 modes,
device_clkandlink_clockneed to be different. This is typical the case in caseSYNTH_DATA_PATH_WIDTHandTPL_DATA_PATH_WIDTHdiffers. Thendevice_clkbecomeslink_clktimesSYNTH_DATA_PATH_WIDTH/TPL_DATA_PATH_WIDTH.link_clkstill needs to belane_clk/ 40 for JESD204B/8B10B encoding andlane_clk/ 66 for JESD204C/64B66B encoding. - conv2: Optional SERDES (CPLL/QPLL) REFCLK from a difference source which rate and state must be in sync with the main conv clk.
Example:
axi_ad9081_rx_jesd: axi-jesd204-rx@84a90000 {
compatible = "adi,axi-jesd204-rx-1.0";
reg = <0x84a90000 0x1000>;
interrupts = <0 107 IRQ_TYPE_LEVEL_HIGH>;
clocks = <&zynqmp_clk 71>, <&hmc7044 10>, <&axi_ad9081_adxcvr_rx 0>;
clock-names = "s_axi_aclk", "device_clk", "lane_clk";
jesd204-device;
#jesd204-cells = <2>;
jesd204-inputs = <&axi_ad9081_adxcvr_rx 0 FRAMER_LINK0_RX>;
};
Enabling Linux driver support
Configure kernel with “make menuconfig” (alternatively use “make xconfig” or “make qconfig”)
Linux Kernel Configuration
Device Drivers --->
<*> Industrial I/O support --->
--- Industrial I/O support
-*- Enable ring buffer support within IIO
-*- Industrial I/O lock free software ring
-*- Enable triggered sampling support
<*> JESD204 High-Speed Serial Interface Support --->
[--snip--]
<*> Analog Devices AXI JESD204B RX Support
[--snip--]
Sysfs Interface
This driver provides advanced diagnostics, status and via sysfs. A brief summary is with examples are provided below.
This specifies any shell prompt running on the target
root@analog:/sys/bus/platform/devices/84a90000.axi-jesd204-rx# ls -al total 0 drwxr-xr-x 4 root root 0 Feb 6 13:41 . drwxr-xr-x 12 root root 0 Feb 6 13:41 .. lrwxrwxrwx 1 root root 0 Feb 6 13:41 driver -> ../../../../bus/platform/drivers/axi-jesd204-rx -rw-r--r-- 1 root root 4096 Feb 6 16:27 driver_override -r--r--r-- 1 root root 4096 Feb 6 16:27 encoder drwxr-xr-x 3 root root 0 Feb 6 13:41 jesd204:4 -r-------- 1 root root 4096 Feb 6 16:27 lane0_info -r-------- 1 root root 4096 Feb 6 16:27 lane1_info -r-------- 1 root root 4096 Feb 6 16:27 lane2_info -r-------- 1 root root 4096 Feb 6 16:27 lane3_info -r-------- 1 root root 4096 Feb 6 16:27 lane4_info -r-------- 1 root root 4096 Feb 6 16:27 lane5_info -r-------- 1 root root 4096 Feb 6 16:27 lane6_info -r-------- 1 root root 4096 Feb 6 16:27 lane7_info -r--r--r-- 1 root root 4096 Feb 6 16:27 modalias lrwxrwxrwx 1 root root 0 Feb 6 16:27 of_node -> ../../../../firmware/devicetree/base/fpga-axi@0/axi-jesd204-rx@84a90000 drwxr-xr-x 2 root root 0 Feb 6 16:27 power -r--r--r-- 1 root root 4096 Feb 6 16:27 status lrwxrwxrwx 1 root root 0 Feb 6 13:41 subsystem -> ../../../../bus/platform -rw-r--r-- 1 root root 4096 Feb 6 13:41 uevent
Reading the device/link status:
| What | Comment |
|---|---|
| Link is [enabled|disabled] | Link state indicator. In case link state is disabled, that either means the link was never enabled or that an error occurred and the FSM rolled back and disabled the link. In the jesd204-fsm case this can be prevented by using the jesd204-ignore-errors; devicetree property when placed in the jesd204-fsm jesd204-top-device node. |
| Link status | Depending on the encoding JESD204B/C 8B10B/64B66B there can be different values RESET, WAIT, CGS, ILAS, etc., DATA Please see link layer documentation for the state machine: JESD204B/C Link Receive Peripheral \ JESD204B/C Link Transmit Peripheral In general DATA is the desired state indicating proper operation. |
| SYNC is [asserted|deasserted] (8B10B only) | State of the external SYNC signal. |
| SYSREF captured: [Yes|No] (Subclass 1 only) | Yes indicates that a SYSREF pulse was captured. |
| SYSREF alignment error: [Yes|No] (Subclass 1 only) | Yes indicates that a SYSREF event has been observed which was unaligned, in regards to the LMFC/LEMC period, to a previously recorded SYSREF event. |
| Lane rate | The SERDES lane rate / bit clock. |
| [LMFC|LEMC] rate | Frequency of the internal local multiframe clocks (LMFC)/ local-multiblock-clock (LEMC). |
| Lane rate / [40|66] | Is equal to the desired Link Clock frequency. |
| Reported Link Clock | Is the Link Clock frequency which is reported by the common clock framework. If this rate is different from the desired Link Clock frequency, there is likely a problem. For example the clock provider wasn’t able to set the desired value. |
| Measured Link Clock | Is the measured Link Clock, using a frequency counter inside the Link Layer Peripheral. For proper operation desired, reported and measured frequency must match. |
| Desired Device Clock | In case this value is different from the Desired Link Clock, this indicates Dual Clock Operation required by the Gearbox. Please see Gearbox/Dual Clock Operation in the Link Layer Peripheral documentation: JESD204B/C Link Receive Peripheral \ JESD204B/C Link Transmit Peripheral The Device Clock is typically generated by the clock provider which also provides SYSREF. |
| Reported Device Clock | Is the Device Clock frequency which is reported by the common clock framework. If this rate is different from the desired Device Clock frequency, there is likely a problem. For example the clock provider wasn’t able to set the desired value. |
| Measured Device Clock | Is the measured Device Clock, using a frequency counter inside the Link Layer Peripheral. For proper operation desired, reported and measured frequency must match. |
This specifies any shell prompt running on the target
root@analog:/sys/bus/platform/devices/84a90000.axi-jesd204-rx# cat status Link is enabled Measured Link Clock: 375.034 MHz Reported Link Clock: 375.000 MHz Measured Device Clock: 375.034 MHz Reported Device Clock: 375.000 MHz Desired Device Clock: 375.000 MHz Lane rate: 15000.000 MHz Lane rate / 40: 375.000 MHz LMFC rate: 46.875 MHz Link status: DATA SYSREF captured: Yes SYSREF alignment error: No
Reading the Encoder used:
This specifies any shell prompt running on the target
root@analog:/sys/bus/platform/devices/84a90000.axi-jesd204-rx# cat encoder 8b10b
Reading the Lane Status:
This specifies any shell prompt running on the target
root@analog:/sys/bus/platform/devices/84a90000.axi-jesd204-rx# cat lane0_info Errors: 0 CGS state: DATA Initial Frame Synchronization: Yes Lane Latency: 3 Multi-frames and 13 Octets Initial Lane Alignment Sequence: Yes DID: 0, BID: 0, LID: 2, L: 8, SCR: 1, F: 1 K: 32, M: 4, N: 16, CS: 0, N': 16, S: 1, HD: 0 FCHK: 0x9, CF: 0 ADJCNT: 0, PHADJ: 0, ADJDIR: 0, JESDV: 1, SUBCLASS: 1 FC: 15000000
More Information
resources/tools-software/linux-drivers/jesd204/axi_jesd204_rx.txt · Last modified: 15 Nov 2023 11:39 by Michael Hennerich