/*
 * Copyright (C) ST-Ericsson AB 2010
 * Author:      Sjur Brendeland/sjur.brandeland@stericsson.com
 * License terms: GNU General Public License (GPL) version 2
 */

#include <linux/string.h>
#include <linux/skbuff.h>
#include <linux/hardirq.h>
#include <net/caif/cfpkt.h>

#define PKT_PREFIX CAIF_NEEDED_HEADROOM
#define PKT_POSTFIX CAIF_NEEDED_TAILROOM
#define PKT_LEN_WHEN_EXTENDING 128
#define PKT_ERROR(pkt, errmsg) do {        \
    cfpkt_priv(pkt)->erronous = true;      \
    skb_reset_tail_pointer(&pkt->skb);     \
    pr_warning("CAIF: " errmsg);\
  } while (0)

struct cfpktq {
        struct sk_buff_head head;
        atomic_t count;
        /* Lock protects count updates */
        spinlock_t lock;
};

/*
 * net/caif/ is generic and does not
 * understand SKB, so we do this typecast
 */
struct cfpkt {
        struct sk_buff skb;
};

/* Private data inside SKB */
struct cfpkt_priv_data {
        struct dev_info dev_info;
        bool erronous;
};

inline struct cfpkt_priv_data *cfpkt_priv(struct cfpkt *pkt)
{
        return (struct cfpkt_priv_data *) pkt->skb.cb;
}

inline bool is_erronous(struct cfpkt *pkt)
{
        return cfpkt_priv(pkt)->erronous;
}

inline struct sk_buff *pkt_to_skb(struct cfpkt *pkt)
{
        return &pkt->skb;
}

inline struct cfpkt *skb_to_pkt(struct sk_buff *skb)
{
        return (struct cfpkt *) skb;
}


struct cfpkt *cfpkt_fromnative(enum caif_direction dir, void *nativepkt)
{
        struct cfpkt *pkt = skb_to_pkt(nativepkt);
        cfpkt_priv(pkt)->erronous = false;
        return pkt;
}
EXPORT_SYMBOL(cfpkt_fromnative);

void *cfpkt_tonative(struct cfpkt *pkt)
{
        return (void *) pkt;
}
EXPORT_SYMBOL(cfpkt_tonative);

static struct cfpkt *cfpkt_create_pfx(u16 len, u16 pfx)
{
        struct sk_buff *skb;

        if (likely(in_interrupt()))
                skb = alloc_skb(len + pfx, GFP_ATOMIC);
        else
                skb = alloc_skb(len + pfx, GFP_KERNEL);

        if (unlikely(skb == NULL))
                return NULL;

        skb_reserve(skb, pfx);
        return skb_to_pkt(skb);
}

inline struct cfpkt *cfpkt_create(u16 len)
{
        return cfpkt_create_pfx(len + PKT_POSTFIX, PKT_PREFIX);
}
EXPORT_SYMBOL(cfpkt_create);

void cfpkt_destroy(struct cfpkt *pkt)
{
        struct sk_buff *skb = pkt_to_skb(pkt);
        kfree_skb(skb);
}
EXPORT_SYMBOL(cfpkt_destroy);

inline bool cfpkt_more(struct cfpkt *pkt)
{
        struct sk_buff *skb = pkt_to_skb(pkt);
        return skb->len > 0;
}
EXPORT_SYMBOL(cfpkt_more);

int cfpkt_peek_head(struct cfpkt *pkt, void *data, u16 len)
{
        struct sk_buff *skb = pkt_to_skb(pkt);
        if (skb_headlen(skb) >= len) {
                memcpy(data, skb->data, len);
                return 0;
        }
        return !cfpkt_extr_head(pkt, data, len) &&
            !cfpkt_add_head(pkt, data, len);
}
EXPORT_SYMBOL(cfpkt_peek_head);

int cfpkt_extr_head(struct cfpkt *pkt, void *data, u16 len)
{
        struct sk_buff *skb = pkt_to_skb(pkt);
        u8 *from;
        if (unlikely(is_erronous(pkt)))
                return -EPROTO;

        if (unlikely(len > skb->len)) {
                PKT_ERROR(pkt, "cfpkt_extr_head read beyond end of packet\n");
                return -EPROTO;
        }

        if (unlikely(len > skb_headlen(skb))) {
                if (unlikely(skb_linearize(skb) != 0)) {
                        PKT_ERROR(pkt, "cfpkt_extr_head linearize failed\n");
                        return -EPROTO;
                }
        }
        from = skb_pull(skb, len);
        from -= len;
        memcpy(data, from, len);
        return 0;
}
EXPORT_SYMBOL(cfpkt_extr_head);

int cfpkt_extr_trail(struct cfpkt *pkt, void *dta, u16 len)
{
        struct sk_buff *skb = pkt_to_skb(pkt);
        u8 *data = dta;
        u8 *from;
        if (unlikely(is_erronous(pkt)))
                return -EPROTO;

        if (unlikely(skb_linearize(skb) != 0)) {
                PKT_ERROR(pkt, "cfpkt_extr_trail linearize failed\n");
                return -EPROTO;
        }
        if (unlikely(skb->data + len > skb_tail_pointer(skb))) {
                PKT_ERROR(pkt, "cfpkt_extr_trail read beyond end of packet\n");
                return -EPROTO;
        }
        from = skb_tail_pointer(skb) - len;
        skb_trim(skb, skb->len - len);
        memcpy(data, from, len);
        return 0;
}
EXPORT_SYMBOL(cfpkt_extr_trail);

int cfpkt_pad_trail(struct cfpkt *pkt, u16 len)
{
        return cfpkt_add_body(pkt, NULL, len);
}
EXPORT_SYMBOL(cfpkt_pad_trail);

int cfpkt_add_body(struct cfpkt *pkt, const void *data, u16 len)
{
        struct sk_buff *skb = pkt_to_skb(pkt);
        struct sk_buff *lastskb;
        u8 *to;
        u16 addlen = 0;


        if (unlikely(is_erronous(pkt)))
                return -EPROTO;

        lastskb = skb;

        /* Check whether we need to add space at the tail */
        if (unlikely(skb_tailroom(skb) < len)) {
                if (likely(len < PKT_LEN_WHEN_EXTENDING))
                        addlen = PKT_LEN_WHEN_EXTENDING;
                else
                        addlen = len;
        }

        /* Check whether we need to change the SKB before writing to the tail */
        if (unlikely((addlen > 0) || skb_cloned(skb) || skb_shared(skb))) {

                /* Make sure data is writable */
                if (unlikely(skb_cow_data(skb, addlen, &lastskb) < 0)) {
                        PKT_ERROR(pkt, "cfpkt_add_body: cow failed\n");
                        return -EPROTO;
                }
                /*
                 * Is the SKB non-linear after skb_cow_data()? If so, we are
                 * going to add data to the last SKB, so we need to adjust
                 * lengths of the top SKB.
                 */
                if (lastskb != skb) {
                        pr_warning("CAIF: %s(): Packet is non-linear\n",
                                   __func__);
                        skb->len += len;
                        skb->data_len += len;
                }
        }

        /* All set to put the last SKB and optionally write data there. */
        to = skb_put(lastskb, len);
        if (likely(data))
                memcpy(to, data, len);
        return 0;
}
EXPORT_SYMBOL(cfpkt_add_body);

inline int cfpkt_addbdy(struct cfpkt *pkt, u8 data)
{
        return cfpkt_add_body(pkt, &data, 1);
}
EXPORT_SYMBOL(cfpkt_addbdy);

int cfpkt_add_head(struct cfpkt *pkt, const void *data2, u16 len)
{
        struct sk_buff *skb = pkt_to_skb(pkt);
        struct sk_buff *lastskb;
        u8 *to;
        const u8 *data = data2;
        int ret;
        if (unlikely(is_erronous(pkt)))
                return -EPROTO;
        if (unlikely(skb_headroom(skb) < len)) {
                PKT_ERROR(pkt, "cfpkt_add_head: no headroom\n");
                return -EPROTO;
        }

        /* Make sure data is writable */
        ret = skb_cow_data(skb, 0, &lastskb);
        if (unlikely(ret < 0)) {
                PKT_ERROR(pkt, "cfpkt_add_head: cow failed\n");
                return ret;
        }

        to = skb_push(skb, len);
        memcpy(to, data, len);
        return 0;
}
EXPORT_SYMBOL(cfpkt_add_head);

inline int cfpkt_add_trail(struct cfpkt *pkt, const void *data, u16 len)
{
        return cfpkt_add_body(pkt, data, len);
}
EXPORT_SYMBOL(cfpkt_add_trail);

inline u16 cfpkt_getlen(struct cfpkt *pkt)
{
        struct sk_buff *skb = pkt_to_skb(pkt);
        return skb->len;
}
EXPORT_SYMBOL(cfpkt_getlen);

inline u16 cfpkt_iterate(struct cfpkt *pkt,
                            u16 (*iter_func)(u16, void *, u16),
                            u16 data)
{
        /*
         * Don't care about the performance hit of linearizing,
         * Checksum should not be used on high-speed interfaces anyway.
         */
        if (unlikely(is_erronous(pkt)))
                return -EPROTO;
        if (unlikely(skb_linearize(&pkt->skb) != 0)) {
                PKT_ERROR(pkt, "cfpkt_iterate: linearize failed\n");
                return -EPROTO;
        }
        return iter_func(data, pkt->skb.data, cfpkt_getlen(pkt));
}
EXPORT_SYMBOL(cfpkt_iterate);

int cfpkt_setlen(struct cfpkt *pkt, u16 len)
{
        struct sk_buff *skb = pkt_to_skb(pkt);


        if (unlikely(is_erronous(pkt)))
                return -EPROTO;

        if (likely(len <= skb->len)) {
                if (unlikely(skb->data_len))
                        ___pskb_trim(skb, len);
                else
                        skb_trim(skb, len);

                        return cfpkt_getlen(pkt);
        }

        /* Need to expand SKB */
        if (unlikely(!cfpkt_pad_trail(pkt, len - skb->len)))
                PKT_ERROR(pkt, "cfpkt_setlen: skb_pad_trail failed\n");

        return cfpkt_getlen(pkt);
}
EXPORT_SYMBOL(cfpkt_setlen);

struct cfpkt *cfpkt_create_uplink(const unsigned char *data, unsigned int len)
{
        struct cfpkt *pkt = cfpkt_create_pfx(len + PKT_POSTFIX, PKT_PREFIX);
        if (!pkt)
                return NULL;
        if (unlikely(data != NULL))
                cfpkt_add_body(pkt, data, len);
        return pkt;
}
EXPORT_SYMBOL(cfpkt_create_uplink);

struct cfpkt *cfpkt_append(struct cfpkt *dstpkt,
                             struct cfpkt *addpkt,
                             u16 expectlen)
{
        struct sk_buff *dst = pkt_to_skb(dstpkt);
        struct sk_buff *add = pkt_to_skb(addpkt);
        u16 addlen = skb_headlen(add);
        u16 neededtailspace;
        struct sk_buff *tmp;
        u16 dstlen;
        u16 createlen;
        if (unlikely(is_erronous(dstpkt) || is_erronous(addpkt))) {
                cfpkt_destroy(addpkt);
                return dstpkt;
        }
        if (expectlen > addlen)
                neededtailspace = expectlen;
        else
                neededtailspace = addlen;

        if (dst->tail + neededtailspace > dst->end) {
                /* Create a dumplicate of 'dst' with more tail space */
                struct cfpkt *tmppkt;
                dstlen = skb_headlen(dst);
                createlen = dstlen + neededtailspace;
                tmppkt = cfpkt_create(createlen + PKT_PREFIX + PKT_POSTFIX);
                if (tmppkt == NULL)
                        return NULL;
                tmp = pkt_to_skb(tmppkt);
                skb_set_tail_pointer(tmp, dstlen);
                tmp->len = dstlen;
                memcpy(tmp->data, dst->data, dstlen);
                cfpkt_destroy(dstpkt);
                dst = tmp;
        }
        memcpy(skb_tail_pointer(dst), add->data, skb_headlen(add));
        cfpkt_destroy(addpkt);
        dst->tail += addlen;
        dst->len += addlen;
        return skb_to_pkt(dst);
}
EXPORT_SYMBOL(cfpkt_append);

struct cfpkt *cfpkt_split(struct cfpkt *pkt, u16 pos)
{
        struct sk_buff *skb2;
        struct sk_buff *skb = pkt_to_skb(pkt);
        struct cfpkt *tmppkt;
        u8 *split = skb->data + pos;
        u16 len2nd = skb_tail_pointer(skb) - split;

        if (unlikely(is_erronous(pkt)))
                return NULL;

        if (skb->data + pos > skb_tail_pointer(skb)) {
                PKT_ERROR(pkt,
                          "cfpkt_split: trying to split beyond end of packet");
                return NULL;
        }

        /* Create a new packet for the second part of the data */
        tmppkt = cfpkt_create_pfx(len2nd + PKT_PREFIX + PKT_POSTFIX,
                                  PKT_PREFIX);
        if (tmppkt == NULL)
                return NULL;
        skb2 = pkt_to_skb(tmppkt);


        if (skb2 == NULL)
                return NULL;

        /* Reduce the length of the original packet */
        skb_set_tail_pointer(skb, pos);
        skb->len = pos;

        memcpy(skb2->data, split, len2nd);
        skb2->tail += len2nd;
        skb2->len += len2nd;
        return skb_to_pkt(skb2);
}
EXPORT_SYMBOL(cfpkt_split);

char *cfpkt_log_pkt(struct cfpkt *pkt, char *buf, int buflen)
{
        struct sk_buff *skb = pkt_to_skb(pkt);
        char *p = buf;
        int i;

        /*
         * Sanity check buffer length, it needs to be at least as large as
         * the header info: ~=50+ bytes
         */
        if (buflen < 50)
                return NULL;

        snprintf(buf, buflen, "%s: pkt:%p len:%ld(%ld+%ld) {%ld,%ld} data: [",
                is_erronous(pkt) ? "ERRONOUS-SKB" :
                 (skb->data_len != 0 ? "COMPLEX-SKB" : "SKB"),
                 skb,
                 (long) skb->len,
                 (long) (skb_tail_pointer(skb) - skb->data),
                 (long) skb->data_len,
                 (long) (skb->data - skb->head),
                 (long) (skb_tail_pointer(skb) - skb->head));
        p = buf + strlen(buf);

        for (i = 0; i < skb_tail_pointer(skb) - skb->data && i < 300; i++) {
                if (p > buf + buflen - 10) {
                        sprintf(p, "...");
                        p = buf + strlen(buf);
                        break;
                }
                sprintf(p, "%02x,", skb->data[i]);
                p = buf + strlen(buf);
        }
        sprintf(p, "]\n");
        return buf;
}
EXPORT_SYMBOL(cfpkt_log_pkt);

int cfpkt_raw_append(struct cfpkt *pkt, void **buf, unsigned int buflen)
{
        struct sk_buff *skb = pkt_to_skb(pkt);
        struct sk_buff *lastskb;

        caif_assert(buf != NULL);
        if (unlikely(is_erronous(pkt)))
                return -EPROTO;
        /* Make sure SKB is writable */
        if (unlikely(skb_cow_data(skb, 0, &lastskb) < 0)) {
                PKT_ERROR(pkt, "cfpkt_raw_append: skb_cow_data failed\n");
                return -EPROTO;
        }

        if (unlikely(skb_linearize(skb) != 0)) {
                PKT_ERROR(pkt, "cfpkt_raw_append: linearize failed\n");
                return -EPROTO;
        }

        if (unlikely(skb_tailroom(skb) < buflen)) {
                PKT_ERROR(pkt, "cfpkt_raw_append: buffer too short - failed\n");
                return -EPROTO;
        }

        *buf = skb_put(skb, buflen);
        return 1;
}
EXPORT_SYMBOL(cfpkt_raw_append);

int cfpkt_raw_extract(struct cfpkt *pkt, void **buf, unsigned int buflen)
{
        struct sk_buff *skb = pkt_to_skb(pkt);

        caif_assert(buf != NULL);
        if (unlikely(is_erronous(pkt)))
                return -EPROTO;

        if (unlikely(buflen > skb->len)) {
                PKT_ERROR(pkt, "cfpkt_raw_extract: buflen too large "
                                "- failed\n");
                return -EPROTO;
        }

        if (unlikely(buflen > skb_headlen(skb))) {
                if (unlikely(skb_linearize(skb) != 0)) {
                        PKT_ERROR(pkt, "cfpkt_raw_extract: linearize failed\n");
                        return -EPROTO;
                }
        }

        *buf = skb->data;
        skb_pull(skb, buflen);

        return 1;
}
EXPORT_SYMBOL(cfpkt_raw_extract);

inline bool cfpkt_erroneous(struct cfpkt *pkt)
{
        return cfpkt_priv(pkt)->erronous;
}
EXPORT_SYMBOL(cfpkt_erroneous);

struct cfpktq *cfpktq_create(void)
{
        struct cfpktq *q = kmalloc(sizeof(struct cfpktq), GFP_ATOMIC);
        if (!q)
                return NULL;
        skb_queue_head_init(&q->head);
        atomic_set(&q->count, 0);
        spin_lock_init(&q->lock);
        return q;
}
EXPORT_SYMBOL(cfpktq_create);

void cfpkt_queue(struct cfpktq *pktq, struct cfpkt *pkt, unsigned short prio)
{
        atomic_inc(&pktq->count);
        spin_lock(&pktq->lock);
        skb_queue_tail(&pktq->head, pkt_to_skb(pkt));
        spin_unlock(&pktq->lock);

}
EXPORT_SYMBOL(cfpkt_queue);

struct cfpkt *cfpkt_qpeek(struct cfpktq *pktq)
{
        struct cfpkt *tmp;
        spin_lock(&pktq->lock);
        tmp = skb_to_pkt(skb_peek(&pktq->head));
        spin_unlock(&pktq->lock);
        return tmp;
}
EXPORT_SYMBOL(cfpkt_qpeek);

struct cfpkt *cfpkt_dequeue(struct cfpktq *pktq)
{
        struct cfpkt *pkt;
        spin_lock(&pktq->lock);
        pkt = skb_to_pkt(skb_dequeue(&pktq->head));
        if (pkt) {
                atomic_dec(&pktq->count);
                caif_assert(atomic_read(&pktq->count) >= 0);
        }
        spin_unlock(&pktq->lock);
        return pkt;
}
EXPORT_SYMBOL(cfpkt_dequeue);

int cfpkt_qcount(struct cfpktq *pktq)
{
        return atomic_read(&pktq->count);
}
EXPORT_SYMBOL(cfpkt_qcount);

struct cfpkt *cfpkt_clone_release(struct cfpkt *pkt)
{
        struct cfpkt *clone;
        clone  = skb_to_pkt(skb_clone(pkt_to_skb(pkt), GFP_ATOMIC));
        /* Free original packet. */
        cfpkt_destroy(pkt);
        if (!clone)
                return NULL;
        return clone;
}
EXPORT_SYMBOL(cfpkt_clone_release);

struct caif_payload_info *cfpkt_info(struct cfpkt *pkt)
{
        return (struct caif_payload_info *)&pkt_to_skb(pkt)->cb;
}
EXPORT_SYMBOL(cfpkt_info);