// SPDX-License-Identifier: GPL-2.0+
/*
 * net/dsa/tag_ksz.c - Microchip KSZ Switch tag format handling
 * Copyright (c) 2017 Microchip Technology
 */

#include <linux/dsa/ksz_common.h>
#include <linux/etherdevice.h>
#include <linux/list.h>
#include <linux/ptp_classify.h>
#include <net/dsa.h>

#include "tag.h"

#define KSZ8795_NAME "ksz8795"
#define KSZ9477_NAME "ksz9477"
#define KSZ9893_NAME "ksz9893"
#define LAN937X_NAME "lan937x"

/* Typically only one byte is used for tail tag. */
#define KSZ_PTP_TAG_LEN                 4
#define KSZ_EGRESS_TAG_LEN              1
#define KSZ_INGRESS_TAG_LEN             1

#define KSZ_HWTS_EN  0

struct ksz_tagger_private {
        struct ksz_tagger_data data; /* Must be first */
        unsigned long state;
        struct kthread_worker *xmit_worker;
};

static struct ksz_tagger_private *
ksz_tagger_private(struct dsa_switch *ds)
{
        return ds->tagger_data;
}

static void ksz_hwtstamp_set_state(struct dsa_switch *ds, bool on)
{
        struct ksz_tagger_private *priv = ksz_tagger_private(ds);

        if (on)
                set_bit(KSZ_HWTS_EN, &priv->state);
        else
                clear_bit(KSZ_HWTS_EN, &priv->state);
}

static void ksz_disconnect(struct dsa_switch *ds)
{
        struct ksz_tagger_private *priv = ds->tagger_data;

        kthread_destroy_worker(priv->xmit_worker);
        kfree(priv);
        ds->tagger_data = NULL;
}

static int ksz_connect(struct dsa_switch *ds)
{
        struct ksz_tagger_data *tagger_data;
        struct kthread_worker *xmit_worker;
        struct ksz_tagger_private *priv;
        int ret;

        priv = kzalloc_obj(*priv);
        if (!priv)
                return -ENOMEM;

        xmit_worker = kthread_run_worker(0, "dsa%d:%d_xmit",
                                            ds->dst->index, ds->index);
        if (IS_ERR(xmit_worker)) {
                ret = PTR_ERR(xmit_worker);
                kfree(priv);
                return ret;
        }

        priv->xmit_worker = xmit_worker;
        /* Export functions for switch driver use */
        tagger_data = &priv->data;
        tagger_data->hwtstamp_set_state = ksz_hwtstamp_set_state;
        ds->tagger_data = priv;

        return 0;
}

static struct sk_buff *ksz_common_rcv(struct sk_buff *skb,
                                      struct net_device *dev,
                                      unsigned int port, unsigned int len)
{
        skb->dev = dsa_conduit_find_user(dev, 0, port);
        if (!skb->dev)
                return NULL;

        if (pskb_trim_rcsum(skb, skb->len - len))
                return NULL;

        dsa_default_offload_fwd_mark(skb);

        return skb;
}

/*
 * For Ingress (Host -> KSZ8795), 1 byte is added before FCS.
 * ---------------------------------------------------------------------------
 * DA(6bytes)|SA(6bytes)|....|Data(nbytes)|tag(1byte)|FCS(4bytes)
 * ---------------------------------------------------------------------------
 * tag : each bit represents port (eg, 0x01=port1, 0x02=port2, 0x10=port5)
 *
 * For Egress (KSZ8795 -> Host), 1 byte is added before FCS.
 * ---------------------------------------------------------------------------
 * DA(6bytes)|SA(6bytes)|....|Data(nbytes)|tag0(1byte)|FCS(4bytes)
 * ---------------------------------------------------------------------------
 * tag0 : zero-based value represents port
 *        (eg, 0x0=port1, 0x2=port3, 0x3=port4)
 */

#define KSZ8795_TAIL_TAG_EG_PORT_M      GENMASK(1, 0)
#define KSZ8795_TAIL_TAG_OVERRIDE       BIT(6)
#define KSZ8795_TAIL_TAG_LOOKUP         BIT(7)

static struct sk_buff *ksz8795_xmit(struct sk_buff *skb, struct net_device *dev)
{
        struct ethhdr *hdr;
        u8 *tag;

        if (skb->ip_summed == CHECKSUM_PARTIAL && skb_checksum_help(skb))
                return NULL;

        /* Tag encoding */
        tag = skb_put(skb, KSZ_INGRESS_TAG_LEN);
        hdr = skb_eth_hdr(skb);

        *tag = dsa_xmit_port_mask(skb, dev);
        if (is_link_local_ether_addr(hdr->h_dest))
                *tag |= KSZ8795_TAIL_TAG_OVERRIDE;

        return skb;
}

static struct sk_buff *ksz8795_rcv(struct sk_buff *skb, struct net_device *dev)
{
        u8 *tag;

        if (skb_linearize(skb))
                return NULL;

        tag = skb_tail_pointer(skb) - KSZ_EGRESS_TAG_LEN;

        return ksz_common_rcv(skb, dev, tag[0] & KSZ8795_TAIL_TAG_EG_PORT_M,
                              KSZ_EGRESS_TAG_LEN);
}

static const struct dsa_device_ops ksz8795_netdev_ops = {
        .name   = KSZ8795_NAME,
        .proto  = DSA_TAG_PROTO_KSZ8795,
        .xmit   = ksz8795_xmit,
        .rcv    = ksz8795_rcv,
        .needed_tailroom = KSZ_INGRESS_TAG_LEN,
};

DSA_TAG_DRIVER(ksz8795_netdev_ops);
MODULE_ALIAS_DSA_TAG_DRIVER(DSA_TAG_PROTO_KSZ8795, KSZ8795_NAME);

/*
 * For Ingress (Host -> KSZ9477), 2/6 bytes are added before FCS.
 * ---------------------------------------------------------------------------
 * DA(6bytes)|SA(6bytes)|....|Data(nbytes)|ts(4bytes)|tag0(1byte)|tag1(1byte)|
 * FCS(4bytes)
 * ---------------------------------------------------------------------------
 * ts   : time stamp (Present only if PTP is enabled in the Hardware)
 * tag0 : Prioritization (not used now)
 * tag1 : each bit represents port (eg, 0x01=port1, 0x02=port2, 0x10=port5)
 *
 * For Egress (KSZ9477 -> Host), 1/5 bytes is added before FCS.
 * ---------------------------------------------------------------------------
 * DA(6bytes)|SA(6bytes)|....|Data(nbytes)|ts(4bytes)|tag0(1byte)|FCS(4bytes)
 * ---------------------------------------------------------------------------
 * ts   : time stamp (Present only if bit 7 of tag0 is set)
 * tag0 : zero-based value represents port
 *        (eg, 0x00=port1, 0x02=port3, 0x06=port7)
 */

#define KSZ9477_INGRESS_TAG_LEN         2
#define KSZ9477_PTP_TAG_LEN             4
#define KSZ9477_PTP_TAG_INDICATION      BIT(7)

#define KSZ9477_TAIL_TAG_EG_PORT_M      GENMASK(2, 0)
#define KSZ9477_TAIL_TAG_PRIO           GENMASK(8, 7)
#define KSZ9477_TAIL_TAG_OVERRIDE       BIT(9)
#define KSZ9477_TAIL_TAG_LOOKUP         BIT(10)

static void ksz_rcv_timestamp(struct sk_buff *skb, u8 *tag)
{
        u8 *tstamp_raw = tag - KSZ_PTP_TAG_LEN;
        ktime_t tstamp;

        tstamp = ksz_decode_tstamp(get_unaligned_be32(tstamp_raw));
        KSZ_SKB_CB(skb)->tstamp = tstamp;
}

/* Time stamp tag *needs* to be inserted if PTP is enabled in hardware.
 * Regardless of Whether it is a PTP frame or not.
 */
static void ksz_xmit_timestamp(struct dsa_port *dp, struct sk_buff *skb)
{
        struct ksz_tagger_private *priv;
        struct ptp_header *ptp_hdr;
        unsigned int ptp_type;
        u32 tstamp_raw = 0;
        s64 correction;

        priv = ksz_tagger_private(dp->ds);

        if (!test_bit(KSZ_HWTS_EN, &priv->state))
                return;

        if (!KSZ_SKB_CB(skb)->update_correction)
                goto output_tag;

        ptp_type = KSZ_SKB_CB(skb)->ptp_type;

        ptp_hdr = ptp_parse_header(skb, ptp_type);
        if (!ptp_hdr)
                goto output_tag;

        correction = (s64)get_unaligned_be64(&ptp_hdr->correction);

        if (correction < 0) {
                struct timespec64 ts;

                ts = ns_to_timespec64(-correction >> 16);
                tstamp_raw = ((ts.tv_sec & 3) << 30) | ts.tv_nsec;

                /* Set correction field to 0 and update UDP checksum */
                ptp_header_update_correction(skb, ptp_type, ptp_hdr, 0);
        }

output_tag:
        put_unaligned_be32(tstamp_raw, skb_put(skb, KSZ_PTP_TAG_LEN));
}

/* Defer transmit if waiting for egress time stamp is required.  */
static struct sk_buff *ksz_defer_xmit(struct dsa_port *dp, struct sk_buff *skb)
{
        struct ksz_tagger_data *tagger_data = ksz_tagger_data(dp->ds);
        struct ksz_tagger_private *priv = ksz_tagger_private(dp->ds);
        void (*xmit_work_fn)(struct kthread_work *work);
        struct sk_buff *clone = KSZ_SKB_CB(skb)->clone;
        struct ksz_deferred_xmit_work *xmit_work;
        struct kthread_worker *xmit_worker;

        if (!clone)
                return skb;  /* no deferred xmit for this packet */

        xmit_work_fn = tagger_data->xmit_work_fn;
        xmit_worker = priv->xmit_worker;

        if (!xmit_work_fn || !xmit_worker)
                return NULL;

        xmit_work = kzalloc_obj(*xmit_work, GFP_ATOMIC);
        if (!xmit_work)
                return NULL;

        kthread_init_work(&xmit_work->work, xmit_work_fn);
        /* Increase refcount so the kfree_skb in dsa_user_xmit
         * won't really free the packet.
         */
        xmit_work->dp = dp;
        xmit_work->skb = skb_get(skb);

        kthread_queue_work(xmit_worker, &xmit_work->work);

        return NULL;
}

static struct sk_buff *ksz9477_xmit(struct sk_buff *skb,
                                    struct net_device *dev)
{
        u16 queue_mapping = skb_get_queue_mapping(skb);
        u8 prio = netdev_txq_to_tc(dev, queue_mapping);
        struct dsa_port *dp = dsa_user_to_port(dev);
        struct ethhdr *hdr;
        __be16 *tag;
        u16 val;

        if (skb->ip_summed == CHECKSUM_PARTIAL && skb_checksum_help(skb))
                return NULL;

        /* Tag encoding */
        ksz_xmit_timestamp(dp, skb);

        tag = skb_put(skb, KSZ9477_INGRESS_TAG_LEN);
        hdr = skb_eth_hdr(skb);

        val = dsa_xmit_port_mask(skb, dev);
        val |= FIELD_PREP(KSZ9477_TAIL_TAG_PRIO, prio);

        if (is_link_local_ether_addr(hdr->h_dest))
                val |= KSZ9477_TAIL_TAG_OVERRIDE;

        *tag = cpu_to_be16(val);

        return ksz_defer_xmit(dp, skb);
}

static struct sk_buff *ksz9477_rcv(struct sk_buff *skb, struct net_device *dev)
{
        unsigned int len = KSZ_EGRESS_TAG_LEN;
        unsigned int port;
        u8 *tag;

        if (skb_linearize(skb))
                return NULL;

        /* Tag decoding */
        tag = skb_tail_pointer(skb) - KSZ_EGRESS_TAG_LEN;
        port = tag[0] & KSZ9477_TAIL_TAG_EG_PORT_M;

        /* Extra 4-bytes PTP timestamp */
        if (tag[0] & KSZ9477_PTP_TAG_INDICATION) {
                ksz_rcv_timestamp(skb, tag);
                len += KSZ_PTP_TAG_LEN;
        }

        return ksz_common_rcv(skb, dev, port, len);
}

static const struct dsa_device_ops ksz9477_netdev_ops = {
        .name   = KSZ9477_NAME,
        .proto  = DSA_TAG_PROTO_KSZ9477,
        .xmit   = ksz9477_xmit,
        .rcv    = ksz9477_rcv,
        .connect = ksz_connect,
        .disconnect = ksz_disconnect,
        .needed_tailroom = KSZ9477_INGRESS_TAG_LEN + KSZ_PTP_TAG_LEN,
};

DSA_TAG_DRIVER(ksz9477_netdev_ops);
MODULE_ALIAS_DSA_TAG_DRIVER(DSA_TAG_PROTO_KSZ9477, KSZ9477_NAME);

#define KSZ9893_TAIL_TAG_PRIO           GENMASK(4, 3)
#define KSZ9893_TAIL_TAG_OVERRIDE       BIT(5)
#define KSZ9893_TAIL_TAG_LOOKUP         BIT(6)

static struct sk_buff *ksz9893_xmit(struct sk_buff *skb,
                                    struct net_device *dev)
{
        u16 queue_mapping = skb_get_queue_mapping(skb);
        u8 prio = netdev_txq_to_tc(dev, queue_mapping);
        struct dsa_port *dp = dsa_user_to_port(dev);
        struct ethhdr *hdr;
        u8 *tag;

        if (skb->ip_summed == CHECKSUM_PARTIAL && skb_checksum_help(skb))
                return NULL;

        /* Tag encoding */
        ksz_xmit_timestamp(dp, skb);

        tag = skb_put(skb, KSZ_INGRESS_TAG_LEN);
        hdr = skb_eth_hdr(skb);

        *tag = dsa_xmit_port_mask(skb, dev);
        *tag |= FIELD_PREP(KSZ9893_TAIL_TAG_PRIO, prio);

        if (is_link_local_ether_addr(hdr->h_dest))
                *tag |= KSZ9893_TAIL_TAG_OVERRIDE;

        return ksz_defer_xmit(dp, skb);
}

static const struct dsa_device_ops ksz9893_netdev_ops = {
        .name   = KSZ9893_NAME,
        .proto  = DSA_TAG_PROTO_KSZ9893,
        .xmit   = ksz9893_xmit,
        .rcv    = ksz9477_rcv,
        .connect = ksz_connect,
        .disconnect = ksz_disconnect,
        .needed_tailroom = KSZ_INGRESS_TAG_LEN + KSZ_PTP_TAG_LEN,
};

DSA_TAG_DRIVER(ksz9893_netdev_ops);
MODULE_ALIAS_DSA_TAG_DRIVER(DSA_TAG_PROTO_KSZ9893, KSZ9893_NAME);

/* For xmit, 2/6 bytes are added before FCS.
 * ---------------------------------------------------------------------------
 * DA(6bytes)|SA(6bytes)|....|Data(nbytes)|ts(4bytes)|tag0(1byte)|tag1(1byte)|
 * FCS(4bytes)
 * ---------------------------------------------------------------------------
 * ts   : time stamp (Present only if PTP is enabled in the Hardware)
 * tag0 : represents tag override, lookup and valid
 * tag1 : each bit represents port (eg, 0x01=port1, 0x02=port2, 0x80=port8)
 *
 * For rcv, 1/5 bytes is added before FCS.
 * ---------------------------------------------------------------------------
 * DA(6bytes)|SA(6bytes)|....|Data(nbytes)|ts(4bytes)|tag0(1byte)|FCS(4bytes)
 * ---------------------------------------------------------------------------
 * ts   : time stamp (Present only if bit 7 of tag0 is set)
 * tag0 : zero-based value represents port
 *        (eg, 0x00=port1, 0x02=port3, 0x07=port8)
 */
#define LAN937X_EGRESS_TAG_LEN          2

#define LAN937X_TAIL_TAG_BLOCKING_OVERRIDE      BIT(11)
#define LAN937X_TAIL_TAG_LOOKUP                 BIT(12)
#define LAN937X_TAIL_TAG_VALID                  BIT(13)
#define LAN937X_TAIL_TAG_PRIO                   GENMASK(10, 8)
#define LAN937X_TAIL_TAG_PORT_MASK              7

static struct sk_buff *lan937x_xmit(struct sk_buff *skb,
                                    struct net_device *dev)
{
        u16 queue_mapping = skb_get_queue_mapping(skb);
        u8 prio = netdev_txq_to_tc(dev, queue_mapping);
        struct dsa_port *dp = dsa_user_to_port(dev);
        const struct ethhdr *hdr = eth_hdr(skb);
        __be16 *tag;
        u16 val;

        if (skb->ip_summed == CHECKSUM_PARTIAL && skb_checksum_help(skb))
                return NULL;

        ksz_xmit_timestamp(dp, skb);

        tag = skb_put(skb, LAN937X_EGRESS_TAG_LEN);

        val = dsa_xmit_port_mask(skb, dev);
        val |= FIELD_PREP(LAN937X_TAIL_TAG_PRIO, prio);

        if (is_link_local_ether_addr(hdr->h_dest))
                val |= LAN937X_TAIL_TAG_BLOCKING_OVERRIDE;

        /* Tail tag valid bit - This bit should always be set by the CPU */
        val |= LAN937X_TAIL_TAG_VALID;

        put_unaligned_be16(val, tag);

        return ksz_defer_xmit(dp, skb);
}

static const struct dsa_device_ops lan937x_netdev_ops = {
        .name   = LAN937X_NAME,
        .proto  = DSA_TAG_PROTO_LAN937X,
        .xmit   = lan937x_xmit,
        .rcv    = ksz9477_rcv,
        .connect = ksz_connect,
        .disconnect = ksz_disconnect,
        .needed_tailroom = LAN937X_EGRESS_TAG_LEN + KSZ_PTP_TAG_LEN,
};

DSA_TAG_DRIVER(lan937x_netdev_ops);
MODULE_ALIAS_DSA_TAG_DRIVER(DSA_TAG_PROTO_LAN937X, LAN937X_NAME);

static struct dsa_tag_driver *dsa_tag_driver_array[] = {
        &DSA_TAG_DRIVER_NAME(ksz8795_netdev_ops),
        &DSA_TAG_DRIVER_NAME(ksz9477_netdev_ops),
        &DSA_TAG_DRIVER_NAME(ksz9893_netdev_ops),
        &DSA_TAG_DRIVER_NAME(lan937x_netdev_ops),
};

module_dsa_tag_drivers(dsa_tag_driver_array);

MODULE_DESCRIPTION("DSA tag driver for Microchip 8795/937x/9477/9893 families of switches");
MODULE_LICENSE("GPL");