/*
 *   BSD LICENSE
 *
 *   Copyright (C) Cavium networks Ltd. 2017.
 *
 *   Redistribution and use in source and binary forms, with or without
 *   modification, are permitted provided that the following conditions
 *   are met:
 *
 *     * Redistributions of source code must retain the above copyright
 *       notice, this list of conditions and the following disclaimer.
 *     * Redistributions in binary form must reproduce the above copyright
 *       notice, this list of conditions and the following disclaimer in
 *       the documentation and/or other materials provided with the
 *       distribution.
 *     * Neither the name of Cavium networks nor the names of its
 *       contributors may be used to endorse or promote products derived
 *       from this software without specific prior written permission.
 *
 *   THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 *   "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 *   LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 *   A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 *   OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 *   SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 *   LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 *   DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 *   THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 *   (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 *   OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#include <string.h>

#include <rte_atomic.h>
#include <rte_common.h>
#include <rte_cycles.h>
#include <rte_io.h>
#include <rte_spinlock.h>

#include "ssovf_evdev.h"

/* Mbox operation timeout in seconds */
#define MBOX_WAIT_TIME_SEC      3
#define MAX_RAM_MBOX_LEN	((SSOW_BAR4_LEN >> 1) - 8 /* Mbox header */)

/* Mbox channel state */
enum {
	MBOX_CHAN_STATE_REQ = 1,
	MBOX_CHAN_STATE_RES = 0,
};

/* Response messages */
enum {
	MBOX_RET_SUCCESS,
	MBOX_RET_INVALID,
	MBOX_RET_INTERNAL_ERR,
};

struct mbox {
	int init_once;
	uint8_t *ram_mbox_base; /* Base address of mbox message stored in ram */
	uint8_t *reg; /* Store to this register triggers PF mbox interrupt */
	uint16_t tag_own; /* Last tag which was written to own channel */
	rte_spinlock_t lock;
};

static struct mbox octeontx_mbox;

/*
 * Structure used for mbox synchronization
 * This structure sits at the begin of Mbox RAM and used as main
 * synchronization point for channel communication
 */
struct mbox_ram_hdr {
	union {
		uint64_t u64;
		struct {
			uint8_t chan_state : 1;
			uint8_t coproc : 7;
			uint8_t msg;
			uint8_t vfid;
			uint8_t res_code;
			uint16_t tag;
			uint16_t len;
		};
	};
};

static inline void
mbox_send_request(struct mbox *m, struct octeontx_mbox_hdr *hdr,
			const void *txmsg, uint16_t txsize)
{
	struct mbox_ram_hdr old_hdr;
	struct mbox_ram_hdr new_hdr = { {0} };
	uint64_t *ram_mbox_hdr = (uint64_t *)m->ram_mbox_base;
	uint8_t *ram_mbox_msg = m->ram_mbox_base + sizeof(struct mbox_ram_hdr);

	/*
	 * Initialize the channel with the tag left by last send.
	 * On success full mbox send complete, PF increments the tag by one.
	 * The sender can validate integrity of PF message with this scheme
	 */
	old_hdr.u64 = rte_read64(ram_mbox_hdr);
	m->tag_own = (old_hdr.tag + 2) & (~0x1ul); /* next even number */

	/* Copy msg body */
	if (txmsg)
		memcpy(ram_mbox_msg, txmsg, txsize);

	/* Prepare new hdr */
	new_hdr.chan_state = MBOX_CHAN_STATE_REQ;
	new_hdr.coproc = hdr->coproc;
	new_hdr.msg = hdr->msg;
	new_hdr.vfid = hdr->vfid;
	new_hdr.tag = m->tag_own;
	new_hdr.len = txsize;

	/* Write the msg header */
	rte_write64(new_hdr.u64, ram_mbox_hdr);
	rte_io_wmb();
	/* Notify PF about the new msg - write to MBOX reg generates PF IRQ */
	rte_write64(0, m->reg);
}

static inline int
mbox_wait_response(struct mbox *m, struct octeontx_mbox_hdr *hdr,
			void *rxmsg, uint16_t rxsize)
{
	int res = 0, wait;
	uint16_t len;
	struct mbox_ram_hdr rx_hdr;
	uint64_t *ram_mbox_hdr = (uint64_t *)m->ram_mbox_base;
	uint8_t *ram_mbox_msg = m->ram_mbox_base + sizeof(struct mbox_ram_hdr);

	/* Wait for response */
	wait = MBOX_WAIT_TIME_SEC * 1000 * 10;
	while (wait > 0) {
		rte_delay_us(100);
		rx_hdr.u64 = rte_read64(ram_mbox_hdr);
		if (rx_hdr.chan_state == MBOX_CHAN_STATE_RES)
			break;
		--wait;
	}

	hdr->res_code = rx_hdr.res_code;
	m->tag_own++;

	/* Timeout */
	if (wait <= 0) {
		res = -ETIMEDOUT;
		goto error;
	}

	/* Tag mismatch */
	if (m->tag_own != rx_hdr.tag) {
		res = -EINVAL;
		goto error;
	}

	/* PF nacked the msg */
	if (rx_hdr.res_code != MBOX_RET_SUCCESS) {
		res = -EBADMSG;
		goto error;
	}

	len = RTE_MIN(rx_hdr.len, rxsize);
	if (rxmsg)
		memcpy(rxmsg, ram_mbox_msg, len);

	return len;

error:
	ssovf_log_err("Failed to send mbox(%d/%d) coproc=%d msg=%d ret=(%d,%d)",
			m->tag_own, rx_hdr.tag, hdr->msg, hdr->coproc, res,
			hdr->res_code);
	return res;
}

static inline int
mbox_send(struct mbox *m, struct octeontx_mbox_hdr *hdr, const void *txmsg,
		uint16_t txsize, void *rxmsg, uint16_t rxsize)
{
	int res = -EINVAL;

	if (m->init_once == 0 || hdr == NULL ||
		txsize > MAX_RAM_MBOX_LEN || rxsize > MAX_RAM_MBOX_LEN) {
		ssovf_log_err("Invalid init_once=%d hdr=%p txsz=%d rxsz=%d",
				m->init_once, hdr, txsize, rxsize);
		return res;
	}

	rte_spinlock_lock(&m->lock);

	mbox_send_request(m, hdr, txmsg, txsize);
	res = mbox_wait_response(m, hdr, rxmsg, rxsize);

	rte_spinlock_unlock(&m->lock);
	return res;
}

static inline int
mbox_setup(struct mbox *m)
{
	if (unlikely(m->init_once == 0)) {
		rte_spinlock_init(&m->lock);
		m->ram_mbox_base = octeontx_ssovf_bar(OCTEONTX_SSO_HWS, 0, 4);
		m->reg = octeontx_ssovf_bar(OCTEONTX_SSO_GROUP, 0, 0);
		m->reg += SSO_VHGRP_PF_MBOX(1);

		if (m->ram_mbox_base == NULL || m->reg == NULL) {
			ssovf_log_err("Invalid ram_mbox_base=%p or reg=%p",
				m->ram_mbox_base, m->reg);
			return -EINVAL;
		}
		m->init_once = 1;
	}
	return 0;
}

int
octeontx_ssovf_mbox_send(struct octeontx_mbox_hdr *hdr, void *txdata,
				 uint16_t txlen, void *rxdata, uint16_t rxlen)
{
	struct mbox *m = &octeontx_mbox;

	RTE_BUILD_BUG_ON(sizeof(struct mbox_ram_hdr) != 8);
	if (rte_eal_process_type() != RTE_PROC_PRIMARY || mbox_setup(m))
		return -EINVAL;

	return mbox_send(m, hdr, txdata, txlen, rxdata, rxlen);
}