/*
 * Copyright (c) 2017 Linaro Ltd
 *
 * SPDX-License-Identifier: Apache-2.0
 */

#define SYS_LOG_LEVEL CONFIG_SYS_LOG_USB_DEVICE_NETWORK_DEBUG_LEVEL
#define SYS_LOG_DOMAIN "function/eem"
#include <logging/sys_log.h>

#include <net_private.h>
#include <zephyr.h>
#include <usb_device.h>
#include <usb_common.h>

#include <net/net_pkt.h>

#include "netusb.h"

static u8_t tx_buf[NETUSB_MTU], rx_buf[NETUSB_MTU];

static inline u16_t eem_pkt_size(u16_t hdr)
{
	if (hdr & BIT(15)) {
		return hdr & 0x07ff;
	} else {
		return hdr & 0x3fff;
	}
}

static int eem_send(struct net_pkt *pkt)
{
	u8_t sentinel[4] = { 0xde, 0xad, 0xbe, 0xef };
	u16_t *hdr = (u16_t *)&tx_buf[0];
	struct net_buf *frag;
	int ret, len, b_idx = 0;

	/* With EEM, it's possible to send multiple ethernet packets in one
	 * transfer, we don't do that for now.
	 */
	len = net_pkt_ll_reserve(pkt) + net_pkt_get_len(pkt) + sizeof(sentinel);

	/* Add EEM header */
	*hdr = sys_cpu_to_le16(0x3FFF & len);
	b_idx += sizeof(u16_t);

	/* Add Ethernet Header */
	memcpy(&tx_buf[b_idx], net_pkt_ll(pkt), net_pkt_ll_reserve(pkt));
	b_idx += net_pkt_ll_reserve(pkt);

	/* generate transfer buffer */
	for (frag = pkt->frags; frag; frag = frag->frags) {
		memcpy(&tx_buf[b_idx], frag->data, frag->len);
		b_idx += frag->len;
	}

	/* Add crc-sentinel */
	memcpy(&tx_buf[b_idx], sentinel, sizeof(sentinel));
	b_idx += sizeof(sentinel);

	/* transfer data to host */
	ret = usb_transfer_sync(CONFIG_CDC_EEM_IN_EP_ADDR, tx_buf, b_idx,
				USB_TRANS_WRITE);
	if (ret != b_idx) {
		SYS_LOG_ERR("Transfer failure");
		return -EIO;
	}

	return 0;
}

static void eem_read_cb(u8_t ep, int size, void *priv)
{
	u8_t *ptr = rx_buf;

	do {
		u16_t eem_hdr, eem_size;
		struct net_pkt *pkt;
		struct net_buf *frag;

		if (size < sizeof(u16_t)) {
			break;
		}

		eem_hdr = sys_le16_to_cpu(*(u16_t *)ptr);
		eem_size = eem_pkt_size(eem_hdr);

		if (eem_size + sizeof(u16_t) > size) {
			/* eem pkt greater than transferred data */
			SYS_LOG_ERR("pkt size error");
			break;
		}

		size -= sizeof(u16_t);
		ptr += sizeof(u16_t);

		if (eem_hdr & BIT(15)) {
			/* EEM Command, do nothing for now */
			goto done;
		}

		pkt = net_pkt_get_reserve_rx(0, K_FOREVER);
		if (!pkt) {
			SYS_LOG_ERR("Unable to alloc pkt\n");
			break;
		}

		frag = net_pkt_get_frag(pkt, K_FOREVER);
		if (!frag) {
			SYS_LOG_ERR("Unable to alloc fragment");
			net_pkt_unref(pkt);
			break;
		}

		net_pkt_frag_insert(pkt, frag);

		/* copy payload and discard 32-bit sentinel */
		if (!net_pkt_append_all(pkt, eem_size - 4, ptr, K_FOREVER)) {
			SYS_LOG_ERR("Unable to append pkt\n");
			net_pkt_unref(pkt);
			break;
		}

		netusb_recv(pkt);

done:
		size -= eem_size;
		ptr += eem_size;
	} while (size);

	usb_transfer(CONFIG_CDC_EEM_OUT_EP_ADDR, rx_buf, sizeof(rx_buf),
		     USB_TRANS_READ, eem_read_cb, NULL);
}

static int eem_connect(bool connected)
{
	if (connected) {
		eem_read_cb(CONFIG_CDC_EEM_OUT_EP_ADDR, 0, NULL);
	} else {
		/* Cancel any transfer */
		usb_cancel_transfer(CONFIG_CDC_EEM_OUT_EP_ADDR);
		usb_cancel_transfer(CONFIG_CDC_EEM_IN_EP_ADDR);
	}

	return 0;
}

static struct usb_ep_cfg_data eem_ep_data[] = {
	{
		/* Use transfer API */
		.ep_cb = usb_transfer_ep_callback,
		.ep_addr = CONFIG_CDC_EEM_OUT_EP_ADDR
	},
	{
		/* Use transfer API */
		.ep_cb = usb_transfer_ep_callback,
		.ep_addr = CONFIG_CDC_EEM_IN_EP_ADDR
	},
};

struct netusb_function eem_function = {
	.connect_media = eem_connect,
	.class_handler = NULL,
	.send_pkt = eem_send,
	.num_ep = ARRAY_SIZE(eem_ep_data),
	.ep = eem_ep_data,
};