From: Lei Wei <[email protected]> Add description and high-level diagram for PPE, driver overview and module enable/debug information.
Signed-off-by: Lei Wei <[email protected]> Signed-off-by: Luo Jie <[email protected]> --- .../networking/device_drivers/ethernet/index.rst | 1 + .../device_drivers/ethernet/qualcomm/ppe/ppe.rst | 194 +++++++++++++++++++++ 2 files changed, 195 insertions(+) diff --git a/Documentation/networking/device_drivers/ethernet/index.rst b/Documentation/networking/device_drivers/ethernet/index.rst index 40ac552641a3..0b0a3eef6aae 100644 --- a/Documentation/networking/device_drivers/ethernet/index.rst +++ b/Documentation/networking/device_drivers/ethernet/index.rst @@ -50,6 +50,7 @@ Contents: neterion/s2io netronome/nfp pensando/ionic + qualcomm/ppe/ppe smsc/smc9 stmicro/stmmac ti/cpsw diff --git a/Documentation/networking/device_drivers/ethernet/qualcomm/ppe/ppe.rst b/Documentation/networking/device_drivers/ethernet/qualcomm/ppe/ppe.rst new file mode 100644 index 000000000000..4ab299a28969 --- /dev/null +++ b/Documentation/networking/device_drivers/ethernet/qualcomm/ppe/ppe.rst @@ -0,0 +1,194 @@ +.. SPDX-License-Identifier: GPL-2.0 + +=============================================== +PPE Ethernet Driver for Qualcomm IPQ SoC Family +=============================================== + +Copyright (c) Qualcomm Technologies, Inc. and/or its subsidiaries. + +Author: Lei Wei <[email protected]> + + +Contents +======== + +- `PPE Overview`_ +- `PPE Driver Overview`_ +- `PPE Driver Supported SoCs`_ +- `Enabling the Driver`_ +- `Debugging`_ + + +PPE Overview +============ + +IPQ (Qualcomm Internet Processor) SoC (System-on-Chip) series is Qualcomm's series of +networking SoC for Wi-Fi access points. The PPE (Packet Process Engine) is the Ethernet +packet process engine in the IPQ SoC. + +Below is a simplified hardware diagram of IPQ9574 SoC which includes the PPE engine and +other blocks which are in the SoC but outside the PPE engine. These blocks work together +to enable the Ethernet for the IPQ SoC:: + + +------+ +------+ +------+ +------+ +------+ +------+ start +-------+ + |netdev| |netdev| |netdev| |netdev| |netdev| |netdev|<------|PHYLINK| + +------+ +------+ +------+ +------+ +------+ +------+ stop +-+-+-+-+ + | | | ^ + +-------+ +-------------------------+--------+----------------------+ | | | + | GCC | | | EDMA | | | | | + +---+---+ | PPE +---+----+ | | | | + | clk | | | | | | + +-------->| +-----------------------+------+-----+---------------+ | | | | + | | Switch Core |Port0 | |Port7(EIP FIFO)| | | | | + | | +---+--+ +------+--------+ | | | | + | | | | | | | | | + +-------+ | | +------+---------------+----+ | | | | | + |CMN PLL| | | +---+ +---+ +----+ | +--------+ | | | | | | + +---+---+ | | |BM | |QM | |SCH | | | L2/L3 | ....... | | | | | | + | | | | +---+ +---+ +----+ | +--------+ | | | | | | + | | | | +------+--------------------+ | | | | | + | | | | | | | | | | + | v | | +-----+-+-----+-+-----+-+-+---+--+-----+-+-----+ | | | | | + | +------+ | | |Port1| |Port2| |Port3| |Port4| |Port5| |Port6| | | | | | + | |NSSCC | | | +-----+ +-----+ +-----+ +-----+ +-----+ +-----+ | | mac| | | + | +-+-+--+ | | |MAC0 | |MAC1 | |MAC2 | |MAC3 | |MAC4 | |MAC5 | | |<---+ | | + | ^ | |clk | | +-----+-+-----+-+-----+-+-----+--+-----+-+-----+ | | ops | | + | | | +------>| +----|------|-------|-------|---------|--------|-----+ | | | + | | | +---------------------------------------------------------+ | | + | | | | | | | | | | | + | | | MII clk | QSGMII USXGMII USXGMII | | + | | +--------------->| | | | | | | | + | | +-------------------------+ +---------+ +---------+ | | + | |125/312.5MHz clk| (PCS0) | | (PCS1) | | (PCS2) | pcs ops | | + | +----------------+ UNIPHY0 | | UNIPHY1 | | UNIPHY2 |<--------+ | + +----------------->| | | | | | | + | 31.25MHz ref clk +-------------------------+ +---------+ +---------+ | + | | | | | | | | + | +-----------------------------------------------------+ | + |25/50MHz ref clk| +-------------------------+ +------+ +------+ | link | + +--------------->| | QUAD PHY | | PHY4 | | PHY5 | |---------+ + | +-------------------------+ +------+ +------+ | change + | | + | MDIO bus | + +-----------------------------------------------------+ + +The CMN (Common) PLL, NSSCC (Networking Sub System Clock Controller) and GCC (Global +Clock Controller) blocks are in the SoC and act as clock providers. + +The UNIPHY block is in the SoC and provides the PCS (Physical Coding Sublayer) and +XPCS (10-Gigabit Physical Coding Sublayer) functions to support different interface +modes between the PPE MAC and the external PHY. + +This documentation focuses on the descriptions of PPE engine and the PPE driver. + +The Ethernet functionality in the PPE (Packet Process Engine) is comprised of three +components: the switch core, port wrapper and Ethernet DMA. + +The Switch core in the IPQ9574 PPE has maximum of 6 front panel ports and two FIFO +interfaces. One of the two FIFO interfaces is used for Ethernet port to host CPU +communication using Ethernet DMA. The other one is used to communicate to the EIP +engine which is used for IPsec offload. On the IPQ9574, the PPE includes 6 GMAC/XGMACs +that can be connected with external Ethernet PHY. Switch core also includes BM (Buffer +Management), QM (Queue Management) and SCH (Scheduler) modules for supporting the +packet processing. + +The port wrapper provides connections from the 6 GMAC/XGMACS to UNIPHY (PCS) supporting +various modes such as SGMII/QSGMII/PSGMII/USXGMII/10G-BASER. There are 3 UNIPHY (PCS) +instances supported on the IPQ9574. + +Ethernet DMA is used to transmit and receive packets between the Ethernet subsystem +and ARM host CPU. + +The following lists the main blocks in the PPE engine which will be driven by this +PPE driver: + +- BM + BM is the hardware buffer manager for the PPE switch ports. +- QM + Queue Manager for managing the egress hardware queues of the PPE switch ports. +- SCH + The scheduler which manages the hardware traffic scheduling for the PPE switch ports. +- L2 + The L2 block performs the packet bridging in the switch core. The bridge domain is + represented by the VSI (Virtual Switch Instance) domain in PPE. FDB learning can be + enabled based on the VSI domain and bridge forwarding occurs within the VSI domain. +- MAC + The PPE in the IPQ9574 supports up to six MACs (MAC0 to MAC5) which are corresponding + to six switch ports (port1 to port6). The MAC block is connected with external PHY + through the UNIPHY PCS block. Each MAC block includes the GMAC and XGMAC blocks and + the switch port can select to use GMAC or XMAC through a MUX selection according to + the external PHY's capability. +- EDMA (Ethernet DMA) + The Ethernet DMA is used to transmit and receive Ethernet packets between the PPE + ports and the ARM cores. + +The received packet on a PPE MAC port can be forwarded to another PPE MAC port. It can +be also forwarded to internal switch port0 so that the packet can be delivered to the +ARM cores using the Ethernet DMA (EDMA) engine. The Ethernet DMA driver will deliver the +packet to the corresponding 'netdevice' interface. + +The software instantiations of the PPE MAC (netdevice), PCS and external PHYs interact +with the Linux PHYLINK framework to manage the connectivity between the PPE ports and +the connected PHYs, and the port link states. This is also illustrated in above diagram. + + +PPE Driver Overview +=================== +PPE driver is Ethernet driver for the Qualcomm IPQ SoC. It is a single platform driver +which includes the PPE part and Ethernet DMA part. The PPE part initializes and drives the +various blocks in PPE switch core such as BM/QM/L2 blocks and the PPE MACs. The EDMA part +drives the Ethernet DMA for packet transfer between PPE ports and ARM cores, and enables +the netdevice driver for the PPE ports. + +The PPE driver files in drivers/net/ethernet/qualcomm/ppe/ are listed as below: + +- Makefile +- ppe.c +- ppe.h +- ppe_config.c +- ppe_config.h +- ppe_debugfs.c +- ppe_debugfs.h +- ppe_regs.h + +The ppe.c file contains the main PPE platform driver and undertakes the initialization of +PPE switch core blocks such as QM, BM and L2. The configuration APIs for these hardware +blocks are provided in the ppe_config.c file. + +The ppe.h defines the PPE device data structure which will be used by PPE driver functions. + +The ppe_debugfs.c enables the PPE statistics counters such as PPE port Rx and Tx counters, +CPU code counters and queue counters. + + +PPE Driver Supported SoCs +========================= + +The PPE driver supports the following IPQ SoC: + +- IPQ9574 + + +Enabling the Driver +=================== + +The driver is located in the menu structure at:: + + -> Device Drivers + -> Network device support (NETDEVICES [=y]) + -> Ethernet driver support + -> Qualcomm devices + -> Qualcomm Technologies, Inc. PPE Ethernet support + +If the driver is built as a module, the module will be called qcom-ppe. + +The PPE driver functionally depends on the CMN PLL and NSSCC clock controller drivers. +Please make sure the dependent modules are installed before installing the PPE driver +module. + + +Debugging +========= + +The PPE hardware counters can be accessed using debugfs interface from the +``/sys/kernel/debug/ppe/`` directory. -- 2.34.1
