// SPDX-License-Identifier: GPL-2.0-only
/* drivers/net/ethernet/micrel/ks8851.c
 *
 * Copyright 2009 Simtec Electronics
 *      http://www.simtec.co.uk/
 *      Ben Dooks <ben@simtec.co.uk>
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/interrupt.h>
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/netdevice.h>
#include <linux/etherdevice.h>
#include <linux/ethtool.h>
#include <linux/cache.h>
#include <linux/crc32.h>
#include <linux/mii.h>
#include <linux/gpio/consumer.h>
#include <linux/regulator/consumer.h>

#include <linux/of_mdio.h>
#include <linux/of_net.h>

#include "ks8851.h"

/**
 * ks8851_lock - register access lock
 * @ks: The chip state
 * @flags: Spinlock flags
 *
 * Claim chip register access lock
 */
static void ks8851_lock(struct ks8851_net *ks, unsigned long *flags)
{
        ks->lock(ks, flags);
}

/**
 * ks8851_unlock - register access unlock
 * @ks: The chip state
 * @flags: Spinlock flags
 *
 * Release chip register access lock
 */
static void ks8851_unlock(struct ks8851_net *ks, unsigned long *flags)
{
        ks->unlock(ks, flags);
}

/**
 * ks8851_wrreg16 - write 16bit register value to chip
 * @ks: The chip state
 * @reg: The register address
 * @val: The value to write
 *
 * Issue a write to put the value @val into the register specified in @reg.
 */
static void ks8851_wrreg16(struct ks8851_net *ks, unsigned int reg,
                           unsigned int val)
{
        ks->wrreg16(ks, reg, val);
}

/**
 * ks8851_rdreg16 - read 16 bit register from device
 * @ks: The chip information
 * @reg: The register address
 *
 * Read a 16bit register from the chip, returning the result
 */
static unsigned int ks8851_rdreg16(struct ks8851_net *ks,
                                   unsigned int reg)
{
        return ks->rdreg16(ks, reg);
}

/**
 * ks8851_soft_reset - issue one of the soft reset to the device
 * @ks: The device state.
 * @op: The bit(s) to set in the GRR
 *
 * Issue the relevant soft-reset command to the device's GRR register
 * specified by @op.
 *
 * Note, the delays are in there as a caution to ensure that the reset
 * has time to take effect and then complete. Since the datasheet does
 * not currently specify the exact sequence, we have chosen something
 * that seems to work with our device.
 */
static void ks8851_soft_reset(struct ks8851_net *ks, unsigned op)
{
        ks8851_wrreg16(ks, KS_GRR, op);
        mdelay(1);      /* wait a short time to effect reset */
        ks8851_wrreg16(ks, KS_GRR, 0);
        mdelay(1);      /* wait for condition to clear */
}

/**
 * ks8851_set_powermode - set power mode of the device
 * @ks: The device state
 * @pwrmode: The power mode value to write to KS_PMECR.
 *
 * Change the power mode of the chip.
 */
static void ks8851_set_powermode(struct ks8851_net *ks, unsigned pwrmode)
{
        unsigned pmecr;

        netif_dbg(ks, hw, ks->netdev, "setting power mode %d\n", pwrmode);

        pmecr = ks8851_rdreg16(ks, KS_PMECR);
        pmecr &= ~PMECR_PM_MASK;
        pmecr |= pwrmode;

        ks8851_wrreg16(ks, KS_PMECR, pmecr);
}

/**
 * ks8851_write_mac_addr - write mac address to device registers
 * @dev: The network device
 *
 * Update the KS8851 MAC address registers from the address in @dev.
 *
 * This call assumes that the chip is not running, so there is no need to
 * shutdown the RXQ process whilst setting this.
*/
static int ks8851_write_mac_addr(struct net_device *dev)
{
        struct ks8851_net *ks = netdev_priv(dev);
        unsigned long flags;
        u16 val;
        int i;

        ks8851_lock(ks, &flags);

        /*
         * Wake up chip in case it was powered off when stopped; otherwise,
         * the first write to the MAC address does not take effect.
         */
        ks8851_set_powermode(ks, PMECR_PM_NORMAL);

        for (i = 0; i < ETH_ALEN; i += 2) {
                val = (dev->dev_addr[i] << 8) | dev->dev_addr[i + 1];
                ks8851_wrreg16(ks, KS_MAR(i), val);
        }

        if (!netif_running(dev))
                ks8851_set_powermode(ks, PMECR_PM_SOFTDOWN);

        ks8851_unlock(ks, &flags);

        return 0;
}

/**
 * ks8851_read_mac_addr - read mac address from device registers
 * @dev: The network device
 *
 * Update our copy of the KS8851 MAC address from the registers of @dev.
*/
static void ks8851_read_mac_addr(struct net_device *dev)
{
        struct ks8851_net *ks = netdev_priv(dev);
        unsigned long flags;
        u8 addr[ETH_ALEN];
        u16 reg;
        int i;

        ks8851_lock(ks, &flags);

        for (i = 0; i < ETH_ALEN; i += 2) {
                reg = ks8851_rdreg16(ks, KS_MAR(i));
                addr[i] = reg >> 8;
                addr[i + 1] = reg & 0xff;
        }
        eth_hw_addr_set(dev, addr);

        ks8851_unlock(ks, &flags);
}

/**
 * ks8851_init_mac - initialise the mac address
 * @ks: The device structure
 * @np: The device node pointer
 *
 * Get or create the initial mac address for the device and then set that
 * into the station address register. A mac address supplied in the device
 * tree takes precedence. Otherwise, if there is an EEPROM present, then
 * we try that. If no valid mac address is found we use eth_random_addr()
 * to create a new one.
 */
static void ks8851_init_mac(struct ks8851_net *ks, struct device_node *np)
{
        struct net_device *dev = ks->netdev;
        int ret;

        ret = of_get_ethdev_address(np, dev);
        if (!ret) {
                ks8851_write_mac_addr(dev);
                return;
        }

        if (ks->rc_ccr & CCR_EEPROM) {
                ks8851_read_mac_addr(dev);
                if (is_valid_ether_addr(dev->dev_addr))
                        return;

                netdev_err(ks->netdev, "invalid mac address read %pM\n",
                                dev->dev_addr);
        }

        eth_hw_addr_random(dev);
        ks8851_write_mac_addr(dev);
}

/**
 * ks8851_rx_pkts - receive packets from the host
 * @ks: The device information.
 * @rxq: Queue of packets received in this function.
 *
 * This is called from the IRQ work queue when the system detects that there
 * are packets in the receive queue. Find out how many packets there are and
 * read them from the FIFO.
 */
static void ks8851_rx_pkts(struct ks8851_net *ks, struct sk_buff_head *rxq)
{
        struct sk_buff *skb;
        unsigned rxfc;
        unsigned rxlen;
        unsigned rxstat;
        u8 *rxpkt;

        rxfc = (ks8851_rdreg16(ks, KS_RXFCTR) >> 8) & 0xff;

        netif_dbg(ks, rx_status, ks->netdev,
                  "%s: %d packets\n", __func__, rxfc);

        /* Currently we're issuing a read per packet, but we could possibly
         * improve the code by issuing a single read, getting the receive
         * header, allocating the packet and then reading the packet data
         * out in one go.
         *
         * This form of operation would require us to hold the SPI bus'
         * chipselect low during the entie transaction to avoid any
         * reset to the data stream coming from the chip.
         */

        for (; rxfc != 0; rxfc--) {
                rxstat = ks8851_rdreg16(ks, KS_RXFHSR);
                rxlen = ks8851_rdreg16(ks, KS_RXFHBCR) & RXFHBCR_CNT_MASK;

                netif_dbg(ks, rx_status, ks->netdev,
                          "rx: stat 0x%04x, len 0x%04x\n", rxstat, rxlen);

                /* the length of the packet includes the 32bit CRC */

                /* set dma read address */
                ks8851_wrreg16(ks, KS_RXFDPR, RXFDPR_RXFPAI | 0x00);

                /* start DMA access */
                ks8851_wrreg16(ks, KS_RXQCR, ks->rc_rxqcr | RXQCR_SDA);

                if (rxlen > 4) {
                        unsigned int rxalign;

                        rxlen -= 4;
                        rxalign = ALIGN(rxlen, 4);
                        skb = netdev_alloc_skb_ip_align(ks->netdev, rxalign);
                        if (skb) {

                                /* 4 bytes of status header + 4 bytes of
                                 * garbage: we put them before ethernet
                                 * header, so that they are copied,
                                 * but ignored.
                                 */

                                rxpkt = skb_put(skb, rxlen) - 8;

                                ks->rdfifo(ks, rxpkt, rxalign + 8);

                                netif_dbg(ks, pktdata, ks->netdev,
                                          "pkt %12ph\n", &rxpkt[4]);

                                skb->protocol = eth_type_trans(skb, ks->netdev);
                                __skb_queue_tail(rxq, skb);

                                ks->netdev->stats.rx_packets++;
                                ks->netdev->stats.rx_bytes += rxlen;
                        }
                }

                /* end DMA access and dequeue packet */
                ks8851_wrreg16(ks, KS_RXQCR, ks->rc_rxqcr | RXQCR_RRXEF);
        }
}

/**
 * ks8851_irq - IRQ handler for dealing with interrupt requests
 * @irq: IRQ number
 * @_ks: cookie
 *
 * This handler is invoked when the IRQ line asserts to find out what happened.
 * As we cannot allow ourselves to sleep in HARDIRQ context, this handler runs
 * in thread context.
 *
 * Read the interrupt status, work out what needs to be done and then clear
 * any of the interrupts that are not needed.
 */
static irqreturn_t ks8851_irq(int irq, void *_ks)
{
        struct ks8851_net *ks = _ks;
        struct sk_buff_head rxq;
        unsigned long flags;
        unsigned int status;
        struct sk_buff *skb;

        ks8851_lock(ks, &flags);

        status = ks8851_rdreg16(ks, KS_ISR);
        ks8851_wrreg16(ks, KS_ISR, status);

        netif_dbg(ks, intr, ks->netdev,
                  "%s: status 0x%04x\n", __func__, status);

        if (status & IRQ_LDI) {
                u16 pmecr = ks8851_rdreg16(ks, KS_PMECR);
                pmecr &= ~PMECR_WKEVT_MASK;
                ks8851_wrreg16(ks, KS_PMECR, pmecr | PMECR_WKEVT_LINK);
        }

        if (status & IRQ_TXI) {
                unsigned short tx_space = ks8851_rdreg16(ks, KS_TXMIR);

                netif_dbg(ks, intr, ks->netdev,
                          "%s: txspace %d\n", __func__, tx_space);

                spin_lock_bh(&ks->statelock);
                ks->tx_space = tx_space;
                if (netif_queue_stopped(ks->netdev))
                        netif_wake_queue(ks->netdev);
                spin_unlock_bh(&ks->statelock);
        }

        if (status & IRQ_SPIBEI) {
                netdev_err(ks->netdev, "%s: spi bus error\n", __func__);
        }

        if (status & IRQ_RXI) {
                /* the datasheet says to disable the rx interrupt during
                 * packet read-out, however we're masking the interrupt
                 * from the device so do not bother masking just the RX
                 * from the device. */

                __skb_queue_head_init(&rxq);
                ks8851_rx_pkts(ks, &rxq);
        }

        /* if something stopped the rx process, probably due to wanting
         * to change the rx settings, then do something about restarting
         * it. */
        if (status & IRQ_RXPSI) {
                struct ks8851_rxctrl *rxc = &ks->rxctrl;

                /* update the multicast hash table */
                ks8851_wrreg16(ks, KS_MAHTR0, rxc->mchash[0]);
                ks8851_wrreg16(ks, KS_MAHTR1, rxc->mchash[1]);
                ks8851_wrreg16(ks, KS_MAHTR2, rxc->mchash[2]);
                ks8851_wrreg16(ks, KS_MAHTR3, rxc->mchash[3]);

                ks8851_wrreg16(ks, KS_RXCR2, rxc->rxcr2);
                ks8851_wrreg16(ks, KS_RXCR1, rxc->rxcr1);
        }

        ks8851_unlock(ks, &flags);

        if (status & IRQ_LCI)
                mii_check_link(&ks->mii);

        if (status & IRQ_RXI)
                while ((skb = __skb_dequeue(&rxq)))
                        netif_rx(skb);

        return IRQ_HANDLED;
}

/**
 * ks8851_flush_tx_work - flush outstanding TX work
 * @ks: The device state
 */
static void ks8851_flush_tx_work(struct ks8851_net *ks)
{
        if (ks->flush_tx_work)
                ks->flush_tx_work(ks);
}

/**
 * ks8851_net_open - open network device
 * @dev: The network device being opened.
 *
 * Called when the network device is marked active, such as a user executing
 * 'ifconfig up' on the device.
 */
static int ks8851_net_open(struct net_device *dev)
{
        struct ks8851_net *ks = netdev_priv(dev);
        unsigned long flags;
        int ret;

        ret = request_threaded_irq(dev->irq, NULL, ks8851_irq,
                                   IRQF_TRIGGER_LOW | IRQF_ONESHOT,
                                   dev->name, ks);
        if (ret < 0) {
                netdev_err(dev, "failed to get irq\n");
                return ret;
        }

        /* lock the card, even if we may not actually be doing anything
         * else at the moment */
        ks8851_lock(ks, &flags);

        netif_dbg(ks, ifup, ks->netdev, "opening\n");

        /* bring chip out of any power saving mode it was in */
        ks8851_set_powermode(ks, PMECR_PM_NORMAL);

        /* issue a soft reset to the RX/TX QMU to put it into a known
         * state. */
        ks8851_soft_reset(ks, GRR_QMU);

        /* setup transmission parameters */

        ks8851_wrreg16(ks, KS_TXCR, (TXCR_TXE | /* enable transmit process */
                                     TXCR_TXPE | /* pad to min length */
                                     TXCR_TXCRC | /* add CRC */
                                     TXCR_TXFCE)); /* enable flow control */

        /* auto-increment tx data, reset tx pointer */
        ks8851_wrreg16(ks, KS_TXFDPR, TXFDPR_TXFPAI);

        /* setup receiver control */

        ks8851_wrreg16(ks, KS_RXCR1, (RXCR1_RXPAFMA | /*  from mac filter */
                                      RXCR1_RXFCE | /* enable flow control */
                                      RXCR1_RXBE | /* broadcast enable */
                                      RXCR1_RXUE | /* unicast enable */
                                      RXCR1_RXE)); /* enable rx block */

        /* transfer entire frames out in one go */
        ks8851_wrreg16(ks, KS_RXCR2, RXCR2_SRDBL_FRAME);

        /* set receive counter timeouts */
        ks8851_wrreg16(ks, KS_RXDTTR, 1000); /* 1ms after first frame to IRQ */
        ks8851_wrreg16(ks, KS_RXDBCTR, 4096); /* >4Kbytes in buffer to IRQ */
        ks8851_wrreg16(ks, KS_RXFCTR, 10);  /* 10 frames to IRQ */

        ks->rc_rxqcr = (RXQCR_RXFCTE |  /* IRQ on frame count exceeded */
                        RXQCR_RXDBCTE | /* IRQ on byte count exceeded */
                        RXQCR_RXDTTE);  /* IRQ on time exceeded */

        ks8851_wrreg16(ks, KS_RXQCR, ks->rc_rxqcr);

        /* clear then enable interrupts */
        ks8851_wrreg16(ks, KS_ISR, ks->rc_ier);
        ks8851_wrreg16(ks, KS_IER, ks->rc_ier);

        ks->queued_len = 0;
        ks->tx_space = ks8851_rdreg16(ks, KS_TXMIR);
        netif_start_queue(ks->netdev);

        netif_dbg(ks, ifup, ks->netdev, "network device up\n");

        ks8851_unlock(ks, &flags);
        mii_check_link(&ks->mii);
        return 0;
}

/**
 * ks8851_net_stop - close network device
 * @dev: The device being closed.
 *
 * Called to close down a network device which has been active. Cancel any
 * work, shutdown the RX and TX process and then place the chip into a low
 * power state whilst it is not being used.
 */
static int ks8851_net_stop(struct net_device *dev)
{
        struct ks8851_net *ks = netdev_priv(dev);
        unsigned long flags;

        netif_info(ks, ifdown, dev, "shutting down\n");

        netif_stop_queue(dev);

        ks8851_lock(ks, &flags);
        /* turn off the IRQs and ack any outstanding */
        ks8851_wrreg16(ks, KS_IER, 0x0000);
        ks8851_wrreg16(ks, KS_ISR, 0xffff);
        ks8851_unlock(ks, &flags);

        /* stop any outstanding work */
        ks8851_flush_tx_work(ks);
        flush_work(&ks->rxctrl_work);

        ks8851_lock(ks, &flags);
        /* shutdown RX process */
        ks8851_wrreg16(ks, KS_RXCR1, 0x0000);

        /* shutdown TX process */
        ks8851_wrreg16(ks, KS_TXCR, 0x0000);

        /* set powermode to soft power down to save power */
        ks8851_set_powermode(ks, PMECR_PM_SOFTDOWN);
        ks8851_unlock(ks, &flags);

        /* ensure any queued tx buffers are dumped */
        while (!skb_queue_empty(&ks->txq)) {
                struct sk_buff *txb = skb_dequeue(&ks->txq);

                netif_dbg(ks, ifdown, ks->netdev,
                          "%s: freeing txb %p\n", __func__, txb);

                dev_kfree_skb(txb);
        }

        free_irq(dev->irq, ks);

        return 0;
}

/**
 * ks8851_start_xmit - transmit packet
 * @skb: The buffer to transmit
 * @dev: The device used to transmit the packet.
 *
 * Called by the network layer to transmit the @skb. Queue the packet for
 * the device and schedule the necessary work to transmit the packet when
 * it is free.
 *
 * We do this to firstly avoid sleeping with the network device locked,
 * and secondly so we can round up more than one packet to transmit which
 * means we can try and avoid generating too many transmit done interrupts.
 */
static netdev_tx_t ks8851_start_xmit(struct sk_buff *skb,
                                     struct net_device *dev)
{
        struct ks8851_net *ks = netdev_priv(dev);

        return ks->start_xmit(skb, dev);
}

/**
 * ks8851_rxctrl_work - work handler to change rx mode
 * @work: The work structure this belongs to.
 *
 * Lock the device and issue the necessary changes to the receive mode from
 * the network device layer. This is done so that we can do this without
 * having to sleep whilst holding the network device lock.
 *
 * Since the recommendation from Micrel is that the RXQ is shutdown whilst the
 * receive parameters are programmed, we issue a write to disable the RXQ and
 * then wait for the interrupt handler to be triggered once the RXQ shutdown is
 * complete. The interrupt handler then writes the new values into the chip.
 */
static void ks8851_rxctrl_work(struct work_struct *work)
{
        struct ks8851_net *ks = container_of(work, struct ks8851_net, rxctrl_work);
        unsigned long flags;

        ks8851_lock(ks, &flags);

        /* need to shutdown RXQ before modifying filter parameters */
        ks8851_wrreg16(ks, KS_RXCR1, 0x00);

        ks8851_unlock(ks, &flags);
}

static void ks8851_set_rx_mode(struct net_device *dev)
{
        struct ks8851_net *ks = netdev_priv(dev);
        struct ks8851_rxctrl rxctrl;

        memset(&rxctrl, 0, sizeof(rxctrl));

        if (dev->flags & IFF_PROMISC) {
                /* interface to receive everything */

                rxctrl.rxcr1 = RXCR1_RXAE | RXCR1_RXINVF;
        } else if (dev->flags & IFF_ALLMULTI) {
                /* accept all multicast packets */

                rxctrl.rxcr1 = (RXCR1_RXME | RXCR1_RXAE |
                                RXCR1_RXPAFMA | RXCR1_RXMAFMA);
        } else if (dev->flags & IFF_MULTICAST && !netdev_mc_empty(dev)) {
                struct netdev_hw_addr *ha;
                u32 crc;

                /* accept some multicast */

                netdev_for_each_mc_addr(ha, dev) {
                        crc = ether_crc(ETH_ALEN, ha->addr);
                        crc >>= (32 - 6);  /* get top six bits */

                        rxctrl.mchash[crc >> 4] |= (1 << (crc & 0xf));
                }

                rxctrl.rxcr1 = RXCR1_RXME | RXCR1_RXPAFMA;
        } else {
                /* just accept broadcast / unicast */
                rxctrl.rxcr1 = RXCR1_RXPAFMA;
        }

        rxctrl.rxcr1 |= (RXCR1_RXUE | /* unicast enable */
                         RXCR1_RXBE | /* broadcast enable */
                         RXCR1_RXE | /* RX process enable */
                         RXCR1_RXFCE); /* enable flow control */

        rxctrl.rxcr2 |= RXCR2_SRDBL_FRAME;

        /* schedule work to do the actual set of the data if needed */

        spin_lock_bh(&ks->statelock);

        if (memcmp(&rxctrl, &ks->rxctrl, sizeof(rxctrl)) != 0) {
                memcpy(&ks->rxctrl, &rxctrl, sizeof(ks->rxctrl));
                schedule_work(&ks->rxctrl_work);
        }

        spin_unlock_bh(&ks->statelock);
}

static int ks8851_set_mac_address(struct net_device *dev, void *addr)
{
        struct sockaddr *sa = addr;

        if (netif_running(dev))
                return -EBUSY;

        if (!is_valid_ether_addr(sa->sa_data))
                return -EADDRNOTAVAIL;

        eth_hw_addr_set(dev, sa->sa_data);
        return ks8851_write_mac_addr(dev);
}

static int ks8851_net_ioctl(struct net_device *dev, struct ifreq *req, int cmd)
{
        struct ks8851_net *ks = netdev_priv(dev);

        if (!netif_running(dev))
                return -EINVAL;

        return generic_mii_ioctl(&ks->mii, if_mii(req), cmd, NULL);
}

static const struct net_device_ops ks8851_netdev_ops = {
        .ndo_open               = ks8851_net_open,
        .ndo_stop               = ks8851_net_stop,
        .ndo_eth_ioctl          = ks8851_net_ioctl,
        .ndo_start_xmit         = ks8851_start_xmit,
        .ndo_set_mac_address    = ks8851_set_mac_address,
        .ndo_set_rx_mode        = ks8851_set_rx_mode,
        .ndo_validate_addr      = eth_validate_addr,
};

/* ethtool support */

static void ks8851_get_drvinfo(struct net_device *dev,
                               struct ethtool_drvinfo *di)
{
        strscpy(di->driver, "KS8851", sizeof(di->driver));
        strscpy(di->version, "1.00", sizeof(di->version));
        strscpy(di->bus_info, dev_name(dev->dev.parent), sizeof(di->bus_info));
}

static u32 ks8851_get_msglevel(struct net_device *dev)
{
        struct ks8851_net *ks = netdev_priv(dev);
        return ks->msg_enable;
}

static void ks8851_set_msglevel(struct net_device *dev, u32 to)
{
        struct ks8851_net *ks = netdev_priv(dev);
        ks->msg_enable = to;
}

static int ks8851_get_link_ksettings(struct net_device *dev,
                                     struct ethtool_link_ksettings *cmd)
{
        struct ks8851_net *ks = netdev_priv(dev);

        mii_ethtool_get_link_ksettings(&ks->mii, cmd);

        return 0;
}

static int ks8851_set_link_ksettings(struct net_device *dev,
                                     const struct ethtool_link_ksettings *cmd)
{
        struct ks8851_net *ks = netdev_priv(dev);
        return mii_ethtool_set_link_ksettings(&ks->mii, cmd);
}

static u32 ks8851_get_link(struct net_device *dev)
{
        struct ks8851_net *ks = netdev_priv(dev);
        return mii_link_ok(&ks->mii);
}

static int ks8851_nway_reset(struct net_device *dev)
{
        struct ks8851_net *ks = netdev_priv(dev);
        return mii_nway_restart(&ks->mii);
}

/* EEPROM support */

static void ks8851_eeprom_regread(struct eeprom_93cx6 *ee)
{
        struct ks8851_net *ks = ee->data;
        unsigned val;

        val = ks8851_rdreg16(ks, KS_EEPCR);

        ee->reg_data_out = (val & EEPCR_EESB) ? 1 : 0;
        ee->reg_data_clock = (val & EEPCR_EESCK) ? 1 : 0;
        ee->reg_chip_select = (val & EEPCR_EECS) ? 1 : 0;
}

static void ks8851_eeprom_regwrite(struct eeprom_93cx6 *ee)
{
        struct ks8851_net *ks = ee->data;
        unsigned val = EEPCR_EESA;      /* default - eeprom access on */

        if (ee->drive_data)
                val |= EEPCR_EESRWA;
        if (ee->reg_data_in)
                val |= EEPCR_EEDO;
        if (ee->reg_data_clock)
                val |= EEPCR_EESCK;
        if (ee->reg_chip_select)
                val |= EEPCR_EECS;

        ks8851_wrreg16(ks, KS_EEPCR, val);
}

/**
 * ks8851_eeprom_claim - claim device EEPROM and activate the interface
 * @ks: The network device state.
 *
 * Check for the presence of an EEPROM, and then activate software access
 * to the device.
 */
static int ks8851_eeprom_claim(struct ks8851_net *ks)
{
        /* start with clock low, cs high */
        ks8851_wrreg16(ks, KS_EEPCR, EEPCR_EESA | EEPCR_EECS);
        return 0;
}

/**
 * ks8851_eeprom_release - release the EEPROM interface
 * @ks: The device state
 *
 * Release the software access to the device EEPROM
 */
static void ks8851_eeprom_release(struct ks8851_net *ks)
{
        unsigned val = ks8851_rdreg16(ks, KS_EEPCR);

        ks8851_wrreg16(ks, KS_EEPCR, val & ~EEPCR_EESA);
}

#define KS_EEPROM_MAGIC (0x00008851)

static int ks8851_set_eeprom(struct net_device *dev,
                             struct ethtool_eeprom *ee, u8 *data)
{
        struct ks8851_net *ks = netdev_priv(dev);
        int offset = ee->offset;
        unsigned long flags;
        int len = ee->len;
        u16 tmp;

        /* currently only support byte writing */
        if (len != 1)
                return -EINVAL;

        if (ee->magic != KS_EEPROM_MAGIC)
                return -EINVAL;

        if (!(ks->rc_ccr & CCR_EEPROM))
                return -ENOENT;

        ks8851_lock(ks, &flags);

        ks8851_eeprom_claim(ks);

        eeprom_93cx6_wren(&ks->eeprom, true);

        /* ethtool currently only supports writing bytes, which means
         * we have to read/modify/write our 16bit EEPROMs */

        eeprom_93cx6_read(&ks->eeprom, offset/2, &tmp);

        if (offset & 1) {
                tmp &= 0xff;
                tmp |= *data << 8;
        } else {
                tmp &= 0xff00;
                tmp |= *data;
        }

        eeprom_93cx6_write(&ks->eeprom, offset/2, tmp);
        eeprom_93cx6_wren(&ks->eeprom, false);

        ks8851_eeprom_release(ks);
        ks8851_unlock(ks, &flags);

        return 0;
}

static int ks8851_get_eeprom(struct net_device *dev,
                             struct ethtool_eeprom *ee, u8 *data)
{
        struct ks8851_net *ks = netdev_priv(dev);
        int offset = ee->offset;
        unsigned long flags;
        int len = ee->len;

        /* must be 2 byte aligned */
        if (len & 1 || offset & 1)
                return -EINVAL;

        if (!(ks->rc_ccr & CCR_EEPROM))
                return -ENOENT;

        ks8851_lock(ks, &flags);

        ks8851_eeprom_claim(ks);

        ee->magic = KS_EEPROM_MAGIC;

        eeprom_93cx6_multiread(&ks->eeprom, offset/2, (__le16 *)data, len/2);
        ks8851_eeprom_release(ks);
        ks8851_unlock(ks, &flags);

        return 0;
}

static int ks8851_get_eeprom_len(struct net_device *dev)
{
        struct ks8851_net *ks = netdev_priv(dev);

        /* currently, we assume it is an 93C46 attached, so return 128 */
        return ks->rc_ccr & CCR_EEPROM ? 128 : 0;
}

static const struct ethtool_ops ks8851_ethtool_ops = {
        .get_drvinfo    = ks8851_get_drvinfo,
        .get_msglevel   = ks8851_get_msglevel,
        .set_msglevel   = ks8851_set_msglevel,
        .get_link       = ks8851_get_link,
        .nway_reset     = ks8851_nway_reset,
        .get_eeprom_len = ks8851_get_eeprom_len,
        .get_eeprom     = ks8851_get_eeprom,
        .set_eeprom     = ks8851_set_eeprom,
        .get_link_ksettings = ks8851_get_link_ksettings,
        .set_link_ksettings = ks8851_set_link_ksettings,
};

/* MII interface controls */

/**
 * ks8851_phy_reg - convert MII register into a KS8851 register
 * @reg: MII register number.
 *
 * Return the KS8851 register number for the corresponding MII PHY register
 * if possible. Return zero if the MII register has no direct mapping to the
 * KS8851 register set.
 */
static int ks8851_phy_reg(int reg)
{
        switch (reg) {
        case MII_BMCR:
                return KS_P1MBCR;
        case MII_BMSR:
                return KS_P1MBSR;
        case MII_PHYSID1:
                return KS_PHY1ILR;
        case MII_PHYSID2:
                return KS_PHY1IHR;
        case MII_ADVERTISE:
                return KS_P1ANAR;
        case MII_LPA:
                return KS_P1ANLPR;
        }

        return -EOPNOTSUPP;
}

static int ks8851_phy_read_common(struct net_device *dev, int phy_addr, int reg)
{
        struct ks8851_net *ks = netdev_priv(dev);
        unsigned long flags;
        int result;
        int ksreg;

        ksreg = ks8851_phy_reg(reg);
        if (ksreg < 0)
                return ksreg;

        ks8851_lock(ks, &flags);
        result = ks8851_rdreg16(ks, ksreg);
        ks8851_unlock(ks, &flags);

        return result;
}

/**
 * ks8851_phy_read - MII interface PHY register read.
 * @dev: The network device the PHY is on.
 * @phy_addr: Address of PHY (ignored as we only have one)
 * @reg: The register to read.
 *
 * This call reads data from the PHY register specified in @reg. Since the
 * device does not support all the MII registers, the non-existent values
 * are always returned as zero.
 *
 * We return zero for unsupported registers as the MII code does not check
 * the value returned for any error status, and simply returns it to the
 * caller. The mii-tool that the driver was tested with takes any -ve error
 * as real PHY capabilities, thus displaying incorrect data to the user.
 */
static int ks8851_phy_read(struct net_device *dev, int phy_addr, int reg)
{
        int ret;

        ret = ks8851_phy_read_common(dev, phy_addr, reg);
        if (ret < 0)
                return 0x0;     /* no error return allowed, so use zero */

        return ret;
}

static void ks8851_phy_write(struct net_device *dev,
                             int phy, int reg, int value)
{
        struct ks8851_net *ks = netdev_priv(dev);
        unsigned long flags;
        int ksreg;

        ksreg = ks8851_phy_reg(reg);
        if (ksreg >= 0) {
                ks8851_lock(ks, &flags);
                ks8851_wrreg16(ks, ksreg, value);
                ks8851_unlock(ks, &flags);
        }
}

static int ks8851_mdio_read(struct mii_bus *bus, int phy_id, int reg)
{
        struct ks8851_net *ks = bus->priv;

        if (phy_id != 0)
                return -EOPNOTSUPP;

        /* KS8851 PHY ID registers are swapped in HW, swap them back. */
        if (reg == MII_PHYSID1)
                reg = MII_PHYSID2;
        else if (reg == MII_PHYSID2)
                reg = MII_PHYSID1;

        return ks8851_phy_read_common(ks->netdev, phy_id, reg);
}

static int ks8851_mdio_write(struct mii_bus *bus, int phy_id, int reg, u16 val)
{
        struct ks8851_net *ks = bus->priv;

        ks8851_phy_write(ks->netdev, phy_id, reg, val);
        return 0;
}

/**
 * ks8851_read_selftest - read the selftest memory info.
 * @ks: The device state
 *
 * Read and check the TX/RX memory selftest information.
 */
static void ks8851_read_selftest(struct ks8851_net *ks)
{
        unsigned both_done = MBIR_TXMBF | MBIR_RXMBF;
        unsigned rd;

        rd = ks8851_rdreg16(ks, KS_MBIR);

        if ((rd & both_done) != both_done) {
                netdev_warn(ks->netdev, "Memory selftest not finished\n");
                return;
        }

        if (rd & MBIR_TXMBFA)
                netdev_err(ks->netdev, "TX memory selftest fail\n");

        if (rd & MBIR_RXMBFA)
                netdev_err(ks->netdev, "RX memory selftest fail\n");
}

/* driver bus management functions */

#ifdef CONFIG_PM_SLEEP

int ks8851_suspend(struct device *dev)
{
        struct ks8851_net *ks = dev_get_drvdata(dev);
        struct net_device *netdev = ks->netdev;

        if (netif_running(netdev)) {
                netif_device_detach(netdev);
                ks8851_net_stop(netdev);
        }

        return 0;
}
EXPORT_SYMBOL_GPL(ks8851_suspend);

int ks8851_resume(struct device *dev)
{
        struct ks8851_net *ks = dev_get_drvdata(dev);
        struct net_device *netdev = ks->netdev;

        if (netif_running(netdev)) {
                ks8851_net_open(netdev);
                netif_device_attach(netdev);
        }

        return 0;
}
EXPORT_SYMBOL_GPL(ks8851_resume);
#endif

static int ks8851_register_mdiobus(struct ks8851_net *ks, struct device *dev)
{
        struct mii_bus *mii_bus;
        int ret;

        mii_bus = mdiobus_alloc();
        if (!mii_bus)
                return -ENOMEM;

        mii_bus->name = "ks8851_eth_mii";
        mii_bus->read = ks8851_mdio_read;
        mii_bus->write = ks8851_mdio_write;
        mii_bus->priv = ks;
        mii_bus->parent = dev;
        mii_bus->phy_mask = ~((u32)BIT(0));
        snprintf(mii_bus->id, MII_BUS_ID_SIZE, "%s", dev_name(dev));

        ret = mdiobus_register(mii_bus);
        if (ret)
                goto err_mdiobus_register;

        ks->mii_bus = mii_bus;

        return 0;

err_mdiobus_register:
        mdiobus_free(mii_bus);
        return ret;
}

static void ks8851_unregister_mdiobus(struct ks8851_net *ks)
{
        mdiobus_unregister(ks->mii_bus);
        mdiobus_free(ks->mii_bus);
}

int ks8851_probe_common(struct net_device *netdev, struct device *dev,
                        int msg_en)
{
        struct ks8851_net *ks = netdev_priv(netdev);
        unsigned cider;
        int ret;

        ks->netdev = netdev;

        ks->gpio = devm_gpiod_get_optional(dev, "reset", GPIOD_OUT_HIGH);
        ret = PTR_ERR_OR_ZERO(ks->gpio);
        if (ret) {
                if (ret != -EPROBE_DEFER)
                        dev_err(dev, "reset gpio request failed: %d\n", ret);
                return ret;
        }

        ret = gpiod_set_consumer_name(ks->gpio, "ks8851_rst_n");
        if (ret) {
                dev_err(dev, "failed to set reset gpio name: %d\n", ret);
                return ret;
        }

        ks->vdd_io = devm_regulator_get(dev, "vdd-io");
        if (IS_ERR(ks->vdd_io)) {
                ret = PTR_ERR(ks->vdd_io);
                goto err_reg_io;
        }

        ret = regulator_enable(ks->vdd_io);
        if (ret) {
                dev_err(dev, "regulator vdd_io enable fail: %d\n", ret);
                goto err_reg_io;
        }

        ks->vdd_reg = devm_regulator_get(dev, "vdd");
        if (IS_ERR(ks->vdd_reg)) {
                ret = PTR_ERR(ks->vdd_reg);
                goto err_reg;
        }

        ret = regulator_enable(ks->vdd_reg);
        if (ret) {
                dev_err(dev, "regulator vdd enable fail: %d\n", ret);
                goto err_reg;
        }

        if (ks->gpio) {
                usleep_range(10000, 11000);
                gpiod_set_value_cansleep(ks->gpio, 0);
        }

        spin_lock_init(&ks->statelock);

        INIT_WORK(&ks->rxctrl_work, ks8851_rxctrl_work);

        SET_NETDEV_DEV(netdev, dev);

        /* setup EEPROM state */
        ks->eeprom.data = ks;
        ks->eeprom.width = PCI_EEPROM_WIDTH_93C46;
        ks->eeprom.register_read = ks8851_eeprom_regread;
        ks->eeprom.register_write = ks8851_eeprom_regwrite;

        /* setup mii state */
        ks->mii.dev             = netdev;
        ks->mii.phy_id          = 1;
        ks->mii.phy_id_mask     = 1;
        ks->mii.reg_num_mask    = 0xf;
        ks->mii.mdio_read       = ks8851_phy_read;
        ks->mii.mdio_write      = ks8851_phy_write;

        dev_info(dev, "message enable is %d\n", msg_en);

        ret = ks8851_register_mdiobus(ks, dev);
        if (ret)
                goto err_mdio;

        /* set the default message enable */
        ks->msg_enable = netif_msg_init(msg_en, NETIF_MSG_DRV |
                                                NETIF_MSG_PROBE |
                                                NETIF_MSG_LINK);

        skb_queue_head_init(&ks->txq);

        netdev->ethtool_ops = &ks8851_ethtool_ops;

        dev_set_drvdata(dev, ks);

        netif_carrier_off(ks->netdev);
        netdev->if_port = IF_PORT_100BASET;
        netdev->netdev_ops = &ks8851_netdev_ops;

        /* issue a global soft reset to reset the device. */
        ks8851_soft_reset(ks, GRR_GSR);

        /* simple check for a valid chip being connected to the bus */
        cider = ks8851_rdreg16(ks, KS_CIDER);
        if ((cider & ~CIDER_REV_MASK) != CIDER_ID) {
                dev_err(dev, "failed to read device ID\n");
                ret = -ENODEV;
                goto err_id;
        }

        /* cache the contents of the CCR register for EEPROM, etc. */
        ks->rc_ccr = ks8851_rdreg16(ks, KS_CCR);

        ks8851_read_selftest(ks);
        ks8851_init_mac(ks, dev->of_node);

        ret = register_netdev(netdev);
        if (ret) {
                dev_err(dev, "failed to register network device\n");
                goto err_id;
        }

        netdev_info(netdev, "revision %d, MAC %pM, IRQ %d, %s EEPROM\n",
                    CIDER_REV_GET(cider), netdev->dev_addr, netdev->irq,
                    ks->rc_ccr & CCR_EEPROM ? "has" : "no");

        return 0;

err_id:
        ks8851_unregister_mdiobus(ks);
err_mdio:
        if (ks->gpio)
                gpiod_set_value_cansleep(ks->gpio, 1);
        regulator_disable(ks->vdd_reg);
err_reg:
        regulator_disable(ks->vdd_io);
err_reg_io:
        return ret;
}
EXPORT_SYMBOL_GPL(ks8851_probe_common);

void ks8851_remove_common(struct device *dev)
{
        struct ks8851_net *priv = dev_get_drvdata(dev);

        ks8851_unregister_mdiobus(priv);

        if (netif_msg_drv(priv))
                dev_info(dev, "remove\n");

        unregister_netdev(priv->netdev);
        if (priv->gpio)
                gpiod_set_value_cansleep(priv->gpio, 1);
        regulator_disable(priv->vdd_reg);
        regulator_disable(priv->vdd_io);
}
EXPORT_SYMBOL_GPL(ks8851_remove_common);

MODULE_DESCRIPTION("KS8851 Network driver");
MODULE_AUTHOR("Ben Dooks <ben@simtec.co.uk>");
MODULE_LICENSE("GPL");