/*
 * Xilinx FPGA Xilinx TSN PTP transfer protocol module.
 *
 * Copyright (c) 2017 Xilinx Pvt., Ltd
 *
 * Author: Syed S <syeds@xilinx.com>
 *
 * This software is licensed under the terms of the GNU General Public
 * License version 2, as published by the Free Software Foundation, and
 * may be copied, distributed, and modified under those terms.
 *
 * 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.
 */

#include "xilinx_axienet.h"
#include "xilinx_tsn_ptp.h"
#include "xilinx_tsn_timer.h"
#include <linux/ptp_classify.h>

#define PTP_ONE_SECOND            1000000000    /**< Value in ns */

#define msg_type_string(type) \
        ((type) == PTP_TYPE_SYNC) ? "SYNC" : \
        ((type) == PTP_TYPE_FOLLOW_UP)            ? "FOLLOW_UP" : \
        ((type) == PTP_TYPE_PDELAYREQ)            ? "PDELAY_REQ" : \
        ((type) == PTP_TYPE_PDELAYRESP)           ? "PDELAY_RESP" : \
        ((type) == PTP_TYPE_PDELAYRESP_FOLLOW_UP) ? "PDELAY_RESP_FOLLOW_UP" : \
        ((type) == PTP_TYPE_ANNOUNCE)             ? "ANNOUNCE" : \
        "UNKNOWN"

/**
 * memcpy_fromio_32 - copy ptp buffer from HW
 * @lp:         Pointer to axienet local structure
 * @offset:     Offset in the PTP buffer
 * @data:       Destination buffer
 * @len:        Len to copy
 *
 * This functions copies the data from PTP buffer to destination data buffer
 */
static void memcpy_fromio_32(struct axienet_local *lp,
                             unsigned long offset, u8 *data, size_t len)
{
        while (len >= 4) {
                *(u32 *)data = axienet_ior(lp, offset);
                len -= 4;
                offset += 4;
                data += 4;
        }

        if (len > 0) {
                u32 leftover = axienet_ior(lp, offset);
                u8 *src = (u8 *)&leftover;

                while (len) {
                        *data++ = *src++;
                        len--;
                }
        }
}

/**
 * memcpy_toio_32 - copy ptp buffer from HW
 * @lp:         Pointer to axienet local structure
 * @offset:     Offset in the PTP buffer
 * @data:       Source data
 * @len:        Len to copy
 *
 * This functions copies the source data to desination ptp buffer
 */
static void memcpy_toio_32(struct axienet_local *lp,
                           unsigned long offset, u8 *data, size_t len)
{
        while (len >= 4) {
                axienet_iow(lp, offset, *(u32 *)data);
                len -= 4;
                offset += 4;
                data += 4;
        }

        if (len > 0) {
                u32 leftover = 0;
                u8 *dest = (u8 *)&leftover;

                while (len) {
                        *dest++ = *data++;
                        len--;
                }
                axienet_iow(lp, offset, leftover);
        }
}

/**
 * axienet_ptp_xmit - xmit skb using PTP HW
 * @skb:        sk_buff pointer that contains data to be Txed.
 * @ndev:       Pointer to net_device structure.
 *
 * Return: NETDEV_TX_OK, on success
 *          NETDEV_TX_BUSY, if any of the descriptors are not free
 *
 * This function is called to transmit a PTP skb. The function uses
 * the free PTP TX buffer entry and sends the frame
 */
int axienet_ptp_xmit(struct sk_buff *skb, struct net_device *ndev)
{
        u8 msg_type;
        struct axienet_local *lp = netdev_priv(ndev);
        unsigned long flags;
        u8 tx_frame_waiting;
        u8 free_index;

        msg_type  = *(u8 *)(skb->data + ETH_HLEN);

        pr_debug("  -->XMIT: protocol: %x message: %s frame_len: %d\n",
                 skb->protocol,
                 msg_type_string(msg_type & 0xf), skb->len);

        tx_frame_waiting =  (axienet_ior(lp, PTP_TX_CONTROL_OFFSET) &
                                PTP_TX_FRAME_WAITING_MASK) >>
                                PTP_TX_FRAME_WAITING_SHIFT;

        /* we reached last frame */
        if (tx_frame_waiting & (1 << 7)) {
                if (!netif_queue_stopped(ndev))
                        netif_stop_queue(ndev);
                pr_debug("tx_frame_waiting: %d\n", tx_frame_waiting);
                return NETDEV_TX_BUSY;
        }

        /* go to next available slot */
        free_index  = fls(tx_frame_waiting);

        /* write the len */
        axienet_iow(lp, PTP_TX_BUFFER_OFFSET(free_index), skb->len);
        memcpy_toio_32(lp, (PTP_TX_BUFFER_OFFSET(free_index) + 8),
                       skb->data, skb->len);

        /* send the frame */
        axienet_iow(lp, PTP_TX_CONTROL_OFFSET, (1 << free_index));

        spin_lock_irqsave(&lp->ptp_tx_lock, flags);
        skb->cb[0] = free_index;
        skb_queue_tail(&lp->ptp_txq, skb);

        if (skb_shinfo(skb)->tx_flags & SKBTX_HW_TSTAMP)
                skb_shinfo(skb)->tx_flags |= SKBTX_IN_PROGRESS;

        skb_tx_timestamp(skb);
        spin_unlock_irqrestore(&lp->ptp_tx_lock, flags);

        return NETDEV_TX_OK;
}

/**
 * axienet_set_timestamp - timestamp skb with HW timestamp
 * @lp:         Pointer to axienet local structure
 * @hwtstamps:  Pointer to skb timestamp structure
 * @offset:     offset of the timestamp in the PTP buffer
 *
 * Return:      None.
 *
 */
static void axienet_set_timestamp(struct axienet_local *lp,
                                  struct skb_shared_hwtstamps *hwtstamps,
                                  unsigned int offset)
{
        u32 captured_ns;
        u32 captured_sec;

        captured_ns = axienet_ior(lp, offset + 4);
        captured_sec = axienet_ior(lp, offset);

        /* Upper 32 bits contain s, lower 32 bits contain ns. */
        hwtstamps->hwtstamp = ktime_set(captured_sec,
                                                captured_ns);
}

/**
 * axienet_ptp_recv - receive ptp buffer in skb from HW
 * @ndev:       Pointer to net_device structure.
 *
 * This function is called from the ptp rx isr. It allocates skb, and
 * copies the ptp rx buffer data to it and calls netif_rx for further
 * processing.
 *
 */
static void axienet_ptp_recv(struct net_device *ndev)
{
        struct axienet_local *lp = netdev_priv(ndev);
        unsigned long ptp_frame_base_addr = 0;
        struct sk_buff *skb;
        u16 msg_len;
        u8 msg_type;
        u32 bytes = 0;
        u32 packets = 0;

        pr_debug("%s:\n ", __func__);

        while (((lp->ptp_rx_hw_pointer & 0xf) !=
                 (lp->ptp_rx_sw_pointer & 0xf))) {
                skb = netdev_alloc_skb(ndev, PTP_RX_FRAME_SIZE);

                lp->ptp_rx_sw_pointer += 1;

                ptp_frame_base_addr = PTP_RX_BASE_OFFSET +
                                   ((lp->ptp_rx_sw_pointer & 0xf) *
                                                        PTP_RX_HWBUF_SIZE);

                memset(skb->data, 0x0, PTP_RX_FRAME_SIZE);

                memcpy_fromio_32(lp, ptp_frame_base_addr, skb->data,
                                 PTP_RX_FRAME_SIZE);

                msg_type  = *(u8 *)(skb->data + ETH_HLEN) & 0xf;
                msg_len  = *(u16 *)(skb->data + ETH_HLEN + 2);

                skb_put(skb, ntohs(msg_len) + ETH_HLEN);

                bytes += skb->len;
                packets++;

                skb->protocol = eth_type_trans(skb, ndev);
                skb->ip_summed = CHECKSUM_UNNECESSARY;

                pr_debug("  -->RECV: protocol: %x message: %s frame_len: %d\n",
                         skb->protocol, msg_type_string(msg_type & 0xf),
                         skb->len);
                /* timestamp only event messages */
                if (!(msg_type & PTP_MSG_TYPE_MASK)) {
                        axienet_set_timestamp(lp, skb_hwtstamps(skb),
                                              (ptp_frame_base_addr +
                                              PTP_HW_TSTAMP_OFFSET));
                }

                netif_rx(skb);
        }
        ndev->stats.rx_packets += packets;
        ndev->stats.rx_bytes += bytes;
}

/**
 * axienet_ptp_rx_irq - PTP RX ISR handler
 * @irq:                irq number
 * @_ndev:      net_device pointer
 *
 * Return:      IRQ_HANDLED for all cases.
 */
irqreturn_t axienet_ptp_rx_irq(int irq, void *_ndev)
{
        struct net_device *ndev = _ndev;
        struct axienet_local *lp = netdev_priv(ndev);

        pr_debug("%s: received\n ", __func__);
        lp->ptp_rx_hw_pointer = (axienet_ior(lp, PTP_RX_CONTROL_OFFSET)
                                        & PTP_RX_PACKET_FIELD_MASK)  >> 8;

        axienet_ptp_recv(ndev);

        return IRQ_HANDLED;
}

/**
 * axienet_tx_tstamp - timestamp skb on trasmit path
 * @work:       Pointer to work_struct structure
 *
 * This adds TX timestamp to skb
 */
void axienet_tx_tstamp(struct work_struct *work)
{
        struct axienet_local *lp = container_of(work, struct axienet_local,
                        tx_tstamp_work);
        struct net_device *ndev = lp->ndev;
        struct skb_shared_hwtstamps hwtstamps;
        struct sk_buff *skb;
        unsigned long ts_reg_offset;
        unsigned long flags;
        u8 tx_packet;
        u8 index;
        u32 bytes = 0;
        u32 packets = 0;

        memset(&hwtstamps, 0, sizeof(struct skb_shared_hwtstamps));

        spin_lock_irqsave(&lp->ptp_tx_lock, flags);

        tx_packet =  (axienet_ior(lp, PTP_TX_CONTROL_OFFSET) &
                                PTP_TX_PACKET_FIELD_MASK) >>
                                PTP_TX_PACKET_FIELD_SHIFT;

        while ((skb = __skb_dequeue(&lp->ptp_txq)) != NULL) {
                index = skb->cb[0];

                /* dequeued packet yet to be xmited? */
                if (index > tx_packet) {
                        /* enqueue it back and break */
                        skb_queue_tail(&lp->ptp_txq, skb);
                        break;
                }
                /* time stamp reg offset */
                ts_reg_offset = PTP_TX_BUFFER_OFFSET(index) +
                                        PTP_HW_TSTAMP_OFFSET;

                if (skb_shinfo(skb)->tx_flags & SKBTX_IN_PROGRESS) {
                        axienet_set_timestamp(lp, &hwtstamps, ts_reg_offset);
                        skb_tstamp_tx(skb, &hwtstamps);
                }

                bytes += skb->len;
                packets++;
                dev_kfree_skb_any(skb);
        }
        ndev->stats.tx_packets += packets;
        ndev->stats.tx_bytes += bytes;

        spin_unlock_irqrestore(&lp->ptp_tx_lock, flags);
}

/**
 * axienet_ptp_tx_irq - PTP TX irq handler
 * @irq:                irq number
 * @_ndev:      net_device pointer
 *
 * Return:      IRQ_HANDLED for all cases.
 *
 */
irqreturn_t axienet_ptp_tx_irq(int irq, void *_ndev)
{
        struct net_device *ndev = _ndev;
        struct axienet_local *lp = netdev_priv(ndev);

        pr_debug("%s: got tx interrupt\n", __func__);

        /* read ctrl register to clear the interrupt */
        axienet_ior(lp, PTP_TX_CONTROL_OFFSET);

        schedule_work(&lp->tx_tstamp_work);

        netif_wake_queue(ndev);

        return IRQ_HANDLED;
}