dwmac.c

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/*
 * Copyright (C) 2025 Michael Brown <mbrown@fensystems.co.uk>.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License as
 * published by the Free Software Foundation; either version 2 of the
 * License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
 * 02110-1301, USA.
 *
 * You can also choose to distribute this program under the terms of
 * the Unmodified Binary Distribution Licence (as given in the file
 * COPYING.UBDL), provided that you have satisfied its requirements.
 */

FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );

#include <stdint.h>
#include <string.h>
#include <errno.h>
#include <byteswap.h>
#include <ipxe/netdevice.h>
#include <ipxe/ethernet.h>
#include <ipxe/if_ether.h>
#include <ipxe/iobuf.h>
#include <ipxe/timer.h>
#include <ipxe/devtree.h>
#include <ipxe/fdt.h>
#include "dwmac.h"

/** @file
 *
 * Synopsys DesignWare MAC network driver
 *
 */

/******************************************************************************
 *
 * Debug
 *
 ******************************************************************************
 */

/**
 * Dump MAC registers (for debugging)
 *
 * @v dwmac             DesignWare MAC device
 */
static void dwmac_dump_mac ( struct dwmac *dwmac ) {

        /* Do nothing unless debugging is enabled */
        if ( ! DBG_LOG )
                return;

        /* Dump MAC registers */
        DBGC ( dwmac, "DWMAC %s ver %08x cfg %08x flt %08x flo %08x\n",
               dwmac->name, readl ( dwmac->regs + DWMAC_VER ),
               readl ( dwmac->regs + DWMAC_CFG ),
               readl ( dwmac->regs + DWMAC_FILTER ),
               readl ( dwmac->regs + DWMAC_FLOW ) );
        DBGC ( dwmac, "DWMAC %s isr %08x dbg %08x gmi %08x\n",
               dwmac->name, readl ( dwmac->regs + DWMAC_ISR ),
               readl ( dwmac->regs + DWMAC_DEBUG ),
               readl ( dwmac->regs + DWMAC_GMII ) );
}

/**
 * Dump DMA registers (for debugging)
 *
 * @v dwmac             DesignWare MAC device
 */
static void dwmac_dump_dma ( struct dwmac *dwmac ) {
        uint32_t status;

        /* Do nothing unless debugging is enabled */
        if ( ! DBG_LOG )
                return;

        /* Dump DMA registers */
        status = readl ( dwmac->regs + DWMAC_STATUS );
        DBGC ( dwmac, "DWMAC %s bus %08x fea %08x axi %08x ahb %08x\n",
               dwmac->name, readl ( dwmac->regs + DWMAC_BUS ),
               readl ( dwmac->regs + DWMAC_FEATURE ),
               readl ( dwmac->regs + DWMAC_AXI ),
               readl ( dwmac->regs + DWMAC_AHB ) );
        DBGC ( dwmac, "DWMAC %s opm %08x sta %08x drp %08x\n",
               dwmac->name, readl ( dwmac->regs + DWMAC_OP ),
               status, readl ( dwmac->regs + DWMAC_DROP ) );
        DBGC ( dwmac, "DWMAC %s txb %08x txd %08x txb %08x\n",
               dwmac->name, readl ( dwmac->regs + DWMAC_TXBASE ),
               readl ( dwmac->regs + DWMAC_TXDESC ),
               readl ( dwmac->regs + DWMAC_TXBUF ) );
        DBGC ( dwmac, "DWMAC %s rxb %08x rxd %08x rxb %08x\n",
               dwmac->name, readl ( dwmac->regs + DWMAC_RXBASE ),
               readl ( dwmac->regs + DWMAC_RXDESC ),
               readl ( dwmac->regs + DWMAC_RXBUF ) );

        /* Clear sticky bits in status register, since nothing else will */
        writel ( status, ( dwmac->regs + DWMAC_STATUS ) );
}

/**
 * Dump all registers (for debugging)
 *
 * @v dwmac             DesignWare MAC device
 */
static void __attribute__ (( unused )) dwmac_dump ( struct dwmac *dwmac ) {

        /* Dump MAC and DMA registers */
        dwmac_dump_mac ( dwmac );
        dwmac_dump_dma ( dwmac );
}

/******************************************************************************
 *
 * Device reset
 *
 ******************************************************************************
 */

/**
 * Reset hardware
 *
 * @v dwmac             DesignWare MAC device
 * @ret rc              Return status code
 */
static int dwmac_reset ( struct dwmac *dwmac ) {
        unsigned int i;
        uint32_t bus;

        /* Trigger software reset */
        writel ( DWMAC_BUS_SWR, ( dwmac->regs + DWMAC_BUS ) );

        /* Wait for reset to complete */
        for ( i = 0 ; i < DWMAC_RESET_MAX_WAIT_MS ; i++ ) {

                /* Delay */
                mdelay ( 1 );

                /* Check for reset completion */
                bus = readl ( dwmac->regs + DWMAC_BUS );
                if ( ! ( bus & DWMAC_BUS_SWR ) )
                        return 0;
        }

        DBGC ( dwmac, "DWMAC %s timed out waiting for reset\n",
               dwmac->name );
        return -ETIMEDOUT;
}

/******************************************************************************
 *
 * Link state
 *
 ******************************************************************************
 */

/**
 * Check link state
 *
 * @v netdev            Network device
 */
static void dwmac_check_link ( struct net_device *netdev ) {
        struct dwmac *dwmac = netdev->priv;
        uint32_t gmii;

        /* Read SGMII/RGMII link status */
        gmii = readl ( dwmac->regs + DWMAC_GMII );
        DBGC ( dwmac, "DWMAC %s GMII link status %#08x\n", dwmac->name, gmii );

        /* Update network device */
        if ( gmii & DWMAC_GMII_LINK ) {
                netdev_link_up ( netdev );
        } else {
                netdev_link_down ( netdev );
        }
}

/******************************************************************************
 *
 * Network device interface
 *
 ******************************************************************************
 */

/**
 * Create descriptor ring
 *
 * @v dwmac             DesignWare MAC device
 * @v ring              Descriptor ring
 * @ret rc              Return status code
 */
static int dwmac_create_ring ( struct dwmac *dwmac, struct dwmac_ring *ring ) {
        struct dwmac_descriptor *desc;
        struct dwmac_descriptor *next;
        physaddr_t base;
        unsigned int i;

        /* Allocate descriptor ring (on its own size) */
        ring->desc = dma_alloc ( dwmac->dma, &ring->map, ring->len, ring->len );
        if ( ! ring->desc )
                return -ENOMEM;

        /* Initialise descriptor ring */
        memset ( ring->desc, 0, ring->len );
        for ( i = 0 ; i < ring->count ; i++ ) {
                desc = &ring->desc[i];
                desc->size = cpu_to_le16 ( DWMAC_RX_LEN |
                                           DWMAC_SIZE_RX_CHAIN );
                desc->ctrl = ring->ctrl;
                assert ( desc->ctrl & DWMAC_CTRL_CHAIN );
                next = &ring->desc[ ( i + 1 ) & ( ring->count - 1 ) ];
                desc->next = dma ( &ring->map, next );
        }
        wmb();

        /* Program ring address */
        base = dma ( &ring->map, ring->desc );
        assert ( base == ( ( uint32_t ) base ) );
        writel ( base, ( dwmac->regs + DWMAC_DMA + ring->qbase ) );

        DBGC ( dwmac, "DWMAC %s ring %02x is at [%08lx,%08lx)\n",
               dwmac->name, ring->qbase, virt_to_phys ( ring->desc ),
               ( virt_to_phys ( ring->desc ) + ring->len ) );
        return 0;
}

/**
 * Destroy descriptor ring
 *
 * @v dwmac             DesignWare MAC device
 * @v ring              Descriptor ring
 */
static void dwmac_destroy_ring ( struct dwmac *dwmac,
                                 struct dwmac_ring *ring ) {

        /* Clear ring address */
        writel ( 0, ( dwmac->regs + DWMAC_DMA + ring->qbase ) );

        /* Free descriptor ring */
        dma_free ( &ring->map, ring->desc, ring->len );
        ring->desc = NULL;
        ring->prod = 0;
        ring->cons = 0;
}

/**
 * Refill receive descriptor ring
 *
 * @v dwmac             DesignWare MAC device
 */
static void dwmac_refill_rx ( struct dwmac *dwmac ) {
        struct dwmac_descriptor *rx;
        struct io_buffer *iobuf;
        unsigned int rx_idx;
        unsigned int refilled = 0;

        /* Refill ring */
        while ( ( dwmac->rx.prod - dwmac->rx.cons ) != DWMAC_NUM_RX_DESC ) {

                /* Allocate I/O buffer */
                iobuf = alloc_rx_iob ( DWMAC_RX_LEN, dwmac->dma );
                if ( ! iobuf ) {
                        /* Wait for next refill */
                        break;
                }

                /* Get next receive descriptor */
                rx_idx = ( dwmac->rx.prod++ % DWMAC_NUM_RX_DESC );
                rx = &dwmac->rx.desc[rx_idx];

                /* Populate receive descriptor */
                rx->addr = cpu_to_le32 ( iob_dma ( iobuf ) );
                wmb();
                rx->stat = cpu_to_le32 ( DWMAC_STAT_OWN );

                /* Record I/O buffer */
                assert ( dwmac->rx_iobuf[rx_idx] == NULL );
                dwmac->rx_iobuf[rx_idx] = iobuf;

                DBGC2 ( dwmac, "DWMAC %s RX %d is [%08lx,%08lx)\n",
                        dwmac->name, rx_idx, virt_to_phys ( iobuf->data ),
                        ( virt_to_phys ( iobuf->data ) + DWMAC_RX_LEN ) );
                refilled++;
        }

        /* Trigger poll */
        if ( refilled ) {
                wmb();
                writel ( 0, ( dwmac->regs + DWMAC_RXPOLL ) );
        }
}

/**
 * Open network device
 *
 * @v netdev            Network device
 * @ret rc              Return status code
 */
static int dwmac_open ( struct net_device *netdev ) {
        struct dwmac *dwmac = netdev->priv;
        union dwmac_mac mac;
        int rc;

        /* Create transmit descriptor ring */
        if ( ( rc = dwmac_create_ring ( dwmac, &dwmac->tx ) ) != 0 )
                goto err_create_tx;

        /* Create receive descriptor ring */
        if ( ( rc = dwmac_create_ring ( dwmac, &dwmac->rx ) ) != 0 )
                goto err_create_rx;

        /* Set MAC address */
        memcpy ( mac.raw, netdev->ll_addr, ETH_ALEN );
        writel ( mac.reg.addrl, ( dwmac->regs + DWMAC_ADDRL ) );
        writel ( mac.reg.addrh, ( dwmac->regs + DWMAC_ADDRH ) );

        /* Enable promiscuous mode */
        writel ( DWMAC_FILTER_PR, ( dwmac->regs + DWMAC_FILTER ) );

        /* Enable transmit and receive */
        writel ( ( DWMAC_OP_TXSF | DWMAC_OP_RXSF |
                   DWMAC_OP_TXEN | DWMAC_OP_RXEN ),
                 ( dwmac->regs + DWMAC_OP ) );
        writel ( ( DWMAC_CFG_DO | DWMAC_CFG_FD |
                   DWMAC_CFG_TXEN | DWMAC_CFG_RXEN ),
                 ( dwmac->regs + DWMAC_CFG ) );

        /* Refill receive descriptor ring */
        dwmac_refill_rx ( dwmac );

        /* Update link state */
        dwmac_check_link ( netdev );

        return 0;

        dwmac_destroy_ring ( dwmac, &dwmac->rx );
 err_create_rx:
        dwmac_destroy_ring ( dwmac, &dwmac->tx );
 err_create_tx:
        return rc;
}

/**
 * Close network device
 *
 * @v netdev            Network device
 */
static void dwmac_close ( struct net_device *netdev ) {
        struct dwmac *dwmac = netdev->priv;
        unsigned int i;

        /* Reset NIC */
        dwmac_reset ( dwmac );

        /* Discard unused receive buffers */
        for ( i = 0 ; i < DWMAC_NUM_RX_DESC ; i++ ) {
                if ( dwmac->rx_iobuf[i] )
                        free_rx_iob ( dwmac->rx_iobuf[i] );
                dwmac->rx_iobuf[i] = NULL;
        }

        /* Destroy receive descriptor ring */
        dwmac_destroy_ring ( dwmac, &dwmac->rx );

        /* Destroy transmit descriptor ring */
        dwmac_destroy_ring ( dwmac, &dwmac->tx );
}

/**
 * Transmit packet
 *
 * @v netdev            Network device
 * @v iobuf             I/O buffer
 * @ret rc              Return status code
 */
static int dwmac_transmit ( struct net_device *netdev,
                            struct io_buffer *iobuf ) {
        struct dwmac *dwmac = netdev->priv;
        struct dwmac_descriptor *tx;
        unsigned int tx_idx;

        /* Get next transmit descriptor */
        if ( ( dwmac->tx.prod - dwmac->tx.cons ) >= DWMAC_NUM_TX_DESC ) {
                DBGC ( dwmac, "DWMAC %s out of transmit descriptors\n",
                       dwmac->name );
                return -ENOBUFS;
        }
        tx_idx = ( dwmac->tx.prod % DWMAC_NUM_TX_DESC );
        tx = &dwmac->tx.desc[tx_idx];

        /* Update producer index */
        dwmac->tx.prod++;

        /* Populate transmit descriptor */
        tx->size = cpu_to_le16 ( iob_len ( iobuf ) );
        tx->addr = cpu_to_le32 ( iob_dma ( iobuf ) );
        wmb();
        tx->stat = cpu_to_le32 ( DWMAC_STAT_OWN | DWMAC_STAT_TX_LAST |
                                 DWMAC_STAT_TX_FIRST | DWMAC_STAT_TX_CHAIN );
        wmb();

        /* Initiate transmission */
        writel ( 0, ( dwmac->regs + DWMAC_TXPOLL ) );

        DBGC2 ( dwmac, "DWMAC %s TX %d is [%08lx,%08lx)\n",
                dwmac->name, tx_idx, virt_to_phys ( iobuf->data ),
                ( virt_to_phys ( iobuf->data ) + iob_len ( iobuf ) ) );
        return 0;
}

/**
 * Poll for completed packets
 *
 * @V netdev            Network device
 */
static void dwmac_poll_tx ( struct net_device *netdev ) {
        struct dwmac *dwmac = netdev->priv;
        struct dwmac_descriptor *tx;
        unsigned int tx_idx;

        /* Check for completed packets */
        while ( dwmac->tx.cons != dwmac->tx.prod ) {

                /* Get next transmit descriptor */
                tx_idx = ( dwmac->tx.cons % DWMAC_NUM_TX_DESC );
                tx = &dwmac->tx.desc[tx_idx];

                /* Stop if descriptor is still owned by hardware */
                if ( tx->stat & cpu_to_le32 ( DWMAC_STAT_OWN ) )
                        return;
                dwmac->tx.cons++;

                /* Report completion */
                if ( tx->stat & cpu_to_le32 ( DWMAC_STAT_ERR ) ) {
                        DBGC ( dwmac, "DWMAC %s TX %d error %#08x\n",
                               dwmac->name, tx_idx, le32_to_cpu ( tx->stat ) );
                        dwmac_dump ( dwmac );
                        netdev_tx_complete_next_err ( netdev, -EIO );
                } else {
                        DBGC2 ( dwmac, "DWMAC %s TX %d complete\n",
                                dwmac->name, tx_idx );
                        netdev_tx_complete_next ( netdev );
                }
        }
}

/**
 * Poll for received packets
 *
 * @v netdev            Network device
 */
static void dwmac_poll_rx ( struct net_device *netdev ) {
        struct dwmac *dwmac = netdev->priv;
        struct dwmac_descriptor *rx;
        struct io_buffer *iobuf;
        unsigned int rx_idx;
        uint32_t stat;
        size_t len;

        /* Check for received packets */
        while ( dwmac->rx.cons != dwmac->rx.prod ) {

                /* Get next receive descriptor */
                rx_idx = ( dwmac->rx.cons % DWMAC_NUM_RX_DESC );
                rx = &dwmac->rx.desc[rx_idx];

                /* Stop if descriptor is still in use */
                if ( rx->stat & cpu_to_le32 ( DWMAC_STAT_OWN ) )
                        return;
                dwmac->rx.cons++;

                /* Consume I/O buffer */
                iobuf = dwmac->rx_iobuf[rx_idx];
                assert ( iobuf != NULL );
                dwmac->rx_iobuf[rx_idx] = NULL;

                /* Hand off to network stack */
                stat = le32_to_cpu ( rx->stat );
                assert ( stat & DWMAC_STAT_RX_FIRST );
                assert ( stat & DWMAC_STAT_RX_LAST );
                if ( stat & DWMAC_STAT_ERR ) {
                        DBGC ( dwmac, "DWMAC %s RX %d error %#08x\n",
                               dwmac->name, rx_idx, stat );
                        dwmac_dump ( dwmac );
                        netdev_rx_err ( netdev, iobuf, -EIO );
                } else {
                        len = ( DWMAC_STAT_RX_LEN ( stat ) - 4 /* CRC */ );
                        iob_put ( iobuf, len );
                        DBGC2 ( dwmac, "DWMAC %s RX %d complete (length "
                                "%zd)\n", dwmac->name, rx_idx, len );
                        netdev_rx ( netdev, iobuf );
                }
        }
}

/**
 * Poll for completed and received packets
 *
 * @v netdev            Network device
 */
static void dwmac_poll ( struct net_device *netdev ) {
        struct dwmac *dwmac = netdev->priv;
        uint32_t status;

        /* Check for link status changes */
        status = readl ( dwmac->regs + DWMAC_STATUS );
        if ( status & DWMAC_STATUS_LINK )
                dwmac_check_link ( netdev );

        /* Poll for TX competions, if applicable */
        dwmac_poll_tx ( netdev );

        /* Poll for RX completions */
        dwmac_poll_rx ( netdev );

        /* Refill RX ring */
        dwmac_refill_rx ( dwmac );
}

/** DesignWare MAC network device operations */
static struct net_device_operations dwmac_operations = {
        .open           = dwmac_open,
        .close          = dwmac_close,
        .transmit       = dwmac_transmit,
        .poll           = dwmac_poll,
};

/******************************************************************************
 *
 * Devicetree interface
 *
 ******************************************************************************
 */

/**
 * Probe devicetree device
 *
 * @v dt                Devicetree device
 * @v offset            Starting node offset
 * @ret rc              Return status code
 */
static int dwmac_probe ( struct dt_device *dt, unsigned int offset ) {
        struct net_device *netdev;
        struct dwmac *dwmac;
        union dwmac_mac mac;
        uint32_t version;
        int rc;

        /* Allocate and initialise net device */
        netdev = alloc_etherdev ( sizeof ( *dwmac ) );
        if ( ! netdev ) {
                rc = -ENOMEM;
                goto err_alloc;
        }
        netdev_init ( netdev, &dwmac_operations );
        dwmac = netdev->priv;
        dt_set_drvdata ( dt, netdev );
        netdev->dev = &dt->dev;
        netdev->dma = &dt->dma;
        memset ( dwmac, 0, sizeof ( *dwmac ) );
        dwmac->dma = &dt->dma;
        dwmac->name = netdev->dev->name;
        dwmac_init_ring ( &dwmac->tx, DWMAC_NUM_TX_DESC, DWMAC_TXBASE,
                          ( DWMAC_CTRL_TX_FIRST | DWMAC_CTRL_TX_LAST |
                            DWMAC_CTRL_CHAIN ) );
        dwmac_init_ring ( &dwmac->rx, DWMAC_NUM_RX_DESC, DWMAC_RXBASE,
                          DWMAC_CTRL_CHAIN );

        /* Map registers */
        dwmac->regs = dt_ioremap ( dt, offset, DWMAC_REG_IDX, DWMAC_REG_LEN );
        if ( ! dwmac->regs ) {
                rc = -ENODEV;
                goto err_ioremap;
        }
        version = readl ( dwmac->regs + DWMAC_VER );
        DBGC ( dwmac, "DWMAC %s version %x.%x (user %x.%x)\n", dwmac->name,
               DWMAC_VER_CORE_MAJOR ( version ),
               DWMAC_VER_CORE_MINOR ( version ),
               DWMAC_VER_USER_MAJOR ( version ),
               DWMAC_VER_USER_MINOR ( version ) );

        /* Fetch devicetree MAC address */
        if ( ( rc = fdt_mac ( &sysfdt, offset, netdev ) ) != 0 ) {
                DBGC ( dwmac, "DWMAC %s could not fetch MAC: %s\n",
                       dwmac->name, strerror ( rc ) );
                goto err_mac;
        }

        /* Fetch current MAC address, if set */
        mac.reg.addrl = readl ( dwmac->regs + DWMAC_ADDRL );
        mac.reg.addrh = readl ( dwmac->regs + DWMAC_ADDRH );
        memcpy ( netdev->ll_addr, mac.raw, ETH_ALEN );

        /* Reset the NIC */
        if ( ( rc = dwmac_reset ( dwmac ) ) != 0 )
                goto err_reset;

        /* Register network device */
        if ( ( rc = register_netdev ( netdev ) ) != 0 )
                goto err_register_netdev;

        /* Update link state */
        dwmac_check_link ( netdev );

        return 0;

        unregister_netdev ( netdev );
 err_register_netdev:
        dwmac_reset ( dwmac );
 err_reset:
 err_mac:
        iounmap ( dwmac->regs );
 err_ioremap:
        netdev_nullify ( netdev );
        netdev_put ( netdev );
 err_alloc:
        return rc;
}

/**
 * Remove devicetree device
 *
 * @v dt                Devicetree device
 */
static void dwmac_remove ( struct dt_device *dt ) {
        struct net_device *netdev = dt_get_drvdata ( dt );
        struct dwmac *dwmac = netdev->priv;

        /* Unregister network device */
        unregister_netdev ( netdev );

        /* Reset card */
        dwmac_reset ( dwmac );

        /* Free network device */
        iounmap ( dwmac->regs );
        netdev_nullify ( netdev );
        netdev_put ( netdev );
}

/** DesignWare MAC compatible model identifiers */
static const char * dwmac_ids[] = {
        "thead,light-dwmac",
        "snps,dwmac",
};

/** DesignWare MAC devicetree driver */
struct dt_driver dwmac_driver __dt_driver = {
        .name = "dwmac",
        .ids = dwmac_ids,
        .id_count = ( sizeof ( dwmac_ids ) / sizeof ( dwmac_ids[0] ) ),
        .probe = dwmac_probe,
        .remove = dwmac_remove,
};