/*
 *  Driver for the NXP SAA7164 PCIe bridge
 *
 *  Copyright (c) 2010-2015 Steven Toth <stoth@kernellabs.com>
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2 of the License, or
 *  (at your option) any later version.
 *
 *  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 "saa7164.h"

/* The message bus to/from the firmware is a ring buffer in PCI address
 * space. Establish the defaults.
 */
int saa7164_bus_setup(struct saa7164_dev *dev)
{
	struct tmComResBusInfo *b	= &dev->bus;

	mutex_init(&b->lock);

	b->Type			= TYPE_BUS_PCIe;
	b->m_wMaxReqSize	= SAA_DEVICE_MAXREQUESTSIZE;

	b->m_pdwSetRing		= (u8 __iomem *)(dev->bmmio +
		((u32)dev->busdesc.CommandRing));

	b->m_dwSizeSetRing	= SAA_DEVICE_BUFFERBLOCKSIZE;

	b->m_pdwGetRing		= (u8 __iomem *)(dev->bmmio +
		((u32)dev->busdesc.ResponseRing));

	b->m_dwSizeGetRing	= SAA_DEVICE_BUFFERBLOCKSIZE;

	b->m_dwSetWritePos	= ((u32)dev->intfdesc.BARLocation) +
		(2 * sizeof(u64));
	b->m_dwSetReadPos	= b->m_dwSetWritePos + (1 * sizeof(u32));

	b->m_dwGetWritePos	= b->m_dwSetWritePos + (2 * sizeof(u32));
	b->m_dwGetReadPos	= b->m_dwSetWritePos + (3 * sizeof(u32));

	return 0;
}

void saa7164_bus_dump(struct saa7164_dev *dev)
{
	struct tmComResBusInfo *b = &dev->bus;

	dprintk(DBGLVL_BUS, "Dumping the bus structure:\n");
	dprintk(DBGLVL_BUS, " .type             = %d\n", b->Type);
	dprintk(DBGLVL_BUS, " .dev->bmmio       = 0x%p\n", dev->bmmio);
	dprintk(DBGLVL_BUS, " .m_wMaxReqSize    = 0x%x\n", b->m_wMaxReqSize);
	dprintk(DBGLVL_BUS, " .m_pdwSetRing     = 0x%p\n", b->m_pdwSetRing);
	dprintk(DBGLVL_BUS, " .m_dwSizeSetRing  = 0x%x\n", b->m_dwSizeSetRing);
	dprintk(DBGLVL_BUS, " .m_pdwGetRing     = 0x%p\n", b->m_pdwGetRing);
	dprintk(DBGLVL_BUS, " .m_dwSizeGetRing  = 0x%x\n", b->m_dwSizeGetRing);

	dprintk(DBGLVL_BUS, " .m_dwSetReadPos   = 0x%x (0x%08x)\n",
		b->m_dwSetReadPos, saa7164_readl(b->m_dwSetReadPos));

	dprintk(DBGLVL_BUS, " .m_dwSetWritePos  = 0x%x (0x%08x)\n",
		b->m_dwSetWritePos, saa7164_readl(b->m_dwSetWritePos));

	dprintk(DBGLVL_BUS, " .m_dwGetReadPos   = 0x%x (0x%08x)\n",
		b->m_dwGetReadPos, saa7164_readl(b->m_dwGetReadPos));

	dprintk(DBGLVL_BUS, " .m_dwGetWritePos  = 0x%x (0x%08x)\n",
		b->m_dwGetWritePos, saa7164_readl(b->m_dwGetWritePos));

}

/* Intensionally throw a BUG() if the state of the message bus looks corrupt */
static void saa7164_bus_verify(struct saa7164_dev *dev)
{
	struct tmComResBusInfo *b = &dev->bus;
	int bug = 0;

	if (saa7164_readl(b->m_dwSetReadPos) > b->m_dwSizeSetRing)
		bug++;

	if (saa7164_readl(b->m_dwSetWritePos) > b->m_dwSizeSetRing)
		bug++;

	if (saa7164_readl(b->m_dwGetReadPos) > b->m_dwSizeGetRing)
		bug++;

	if (saa7164_readl(b->m_dwGetWritePos) > b->m_dwSizeGetRing)
		bug++;

	if (bug) {
		saa_debug = 0xffff; /* Ensure we get the bus dump */
		saa7164_bus_dump(dev);
		saa_debug = 1024; /* Ensure we get the bus dump */
		BUG();
	}
}

static void saa7164_bus_dumpmsg(struct saa7164_dev *dev, struct tmComResInfo *m,
				void *buf)
{
	dprintk(DBGLVL_BUS, "Dumping msg structure:\n");
	dprintk(DBGLVL_BUS, " .id               = %d\n",   m->id);
	dprintk(DBGLVL_BUS, " .flags            = 0x%x\n", m->flags);
	dprintk(DBGLVL_BUS, " .size             = 0x%x\n", m->size);
	dprintk(DBGLVL_BUS, " .command          = 0x%x\n", m->command);
	dprintk(DBGLVL_BUS, " .controlselector  = 0x%x\n", m->controlselector);
	dprintk(DBGLVL_BUS, " .seqno            = %d\n",   m->seqno);
	if (buf)
		dprintk(DBGLVL_BUS, " .buffer (ignored)\n");
}

/*
 * Places a command or a response on the bus. The implementation does not
 * know if it is a command or a response it just places the data on the
 * bus depending on the bus information given in the struct tmComResBusInfo
 * structure. If the command or response does not fit into the bus ring
 * buffer it will be refused.
 *
 * Return Value:
 *  SAA_OK     The function executed successfully.
 *  < 0        One or more members are not initialized.
 */
int saa7164_bus_set(struct saa7164_dev *dev, struct tmComResInfo* msg,
	void *buf)
{
	struct tmComResBusInfo *bus = &dev->bus;
	u32 bytes_to_write, free_write_space, timeout, curr_srp, curr_swp;
	u32 new_swp, space_rem;
	int ret = SAA_ERR_BAD_PARAMETER;
	u16 size;

	if (!msg) {
		printk(KERN_ERR "%s() !msg\n", __func__);
		return SAA_ERR_BAD_PARAMETER;
	}

	dprintk(DBGLVL_BUS, "%s()\n", __func__);

	saa7164_bus_verify(dev);

	if (msg->size > dev->bus.m_wMaxReqSize) {
		printk(KERN_ERR "%s() Exceeded dev->bus.m_wMaxReqSize\n",
			__func__);
		return SAA_ERR_BAD_PARAMETER;
	}

	if ((msg->size > 0) && (buf == NULL)) {
		printk(KERN_ERR "%s() Missing message buffer\n", __func__);
		return SAA_ERR_BAD_PARAMETER;
	}

	/* Lock the bus from any other access */
	mutex_lock(&bus->lock);

	bytes_to_write = sizeof(*msg) + msg->size;
	free_write_space = 0;
	timeout = SAA_BUS_TIMEOUT;
	curr_srp = saa7164_readl(bus->m_dwSetReadPos);
	curr_swp = saa7164_readl(bus->m_dwSetWritePos);

	/* Deal with ring wrapping issues */
	if (curr_srp > curr_swp)
		/* Deal with the wrapped ring */
		free_write_space = curr_srp - curr_swp;
	else
		/* The ring has not wrapped yet */
		free_write_space = (curr_srp + bus->m_dwSizeSetRing) - curr_swp;

	dprintk(DBGLVL_BUS, "%s() bytes_to_write = %d\n", __func__,
		bytes_to_write);

	dprintk(DBGLVL_BUS, "%s() free_write_space = %d\n", __func__,
		free_write_space);

	dprintk(DBGLVL_BUS, "%s() curr_srp = %x\n", __func__, curr_srp);
	dprintk(DBGLVL_BUS, "%s() curr_swp = %x\n", __func__, curr_swp);

	/* Process the msg and write the content onto the bus */
	while (bytes_to_write >= free_write_space) {

		if (timeout-- == 0) {
			printk(KERN_ERR "%s() bus timeout\n", __func__);
			ret = SAA_ERR_NO_RESOURCES;
			goto out;
		}

		/* TODO: Review this delay, efficient? */
		/* Wait, allowing the hardware fetch time */
		mdelay(1);

		/* Check the space usage again */
		curr_srp = saa7164_readl(bus->m_dwSetReadPos);

		/* Deal with ring wrapping issues */
		if (curr_srp > curr_swp)
			/* Deal with the wrapped ring */
			free_write_space = curr_srp - curr_swp;
		else
			/* Read didn't wrap around the buffer */
			free_write_space = (curr_srp + bus->m_dwSizeSetRing) -
				curr_swp;

	}

	/* Calculate the new write position */
	new_swp = curr_swp + bytes_to_write;

	dprintk(DBGLVL_BUS, "%s() new_swp = %x\n", __func__, new_swp);
	dprintk(DBGLVL_BUS, "%s() bus->m_dwSizeSetRing = %x\n", __func__,
		bus->m_dwSizeSetRing);

	/*
	 * Make a copy of msg->size before it is converted to le16 since it is
	 * used in the code below.
	 */
	size = msg->size;
	/* Convert to le16/le32 */
	msg->size = (__force u16)cpu_to_le16(msg->size);
	msg->command = (__force u32)cpu_to_le32(msg->command);
	msg->controlselector = (__force u16)cpu_to_le16(msg->controlselector);

	/* Mental Note: line 462 tmmhComResBusPCIe.cpp */

	/* Check if we're going to wrap again */
	if (new_swp > bus->m_dwSizeSetRing) {

		/* Ring wraps */
		new_swp -= bus->m_dwSizeSetRing;

		space_rem = bus->m_dwSizeSetRing - curr_swp;

		dprintk(DBGLVL_BUS, "%s() space_rem = %x\n", __func__,
			space_rem);

		dprintk(DBGLVL_BUS, "%s() sizeof(*msg) = %d\n", __func__,
			(u32)sizeof(*msg));

		if (space_rem < sizeof(*msg)) {
			dprintk(DBGLVL_BUS, "%s() tr4\n", __func__);

			/* Split the msg into pieces as the ring wraps */
			memcpy_toio(bus->m_pdwSetRing + curr_swp, msg, space_rem);
			memcpy_toio(bus->m_pdwSetRing, (u8 *)msg + space_rem,
				sizeof(*msg) - space_rem);

			memcpy_toio(bus->m_pdwSetRing + sizeof(*msg) - space_rem,
				buf, size);

		} else if (space_rem == sizeof(*msg)) {
			dprintk(DBGLVL_BUS, "%s() tr5\n", __func__);

			/* Additional data at the beginning of the ring */
			memcpy_toio(bus->m_pdwSetRing + curr_swp, msg, sizeof(*msg));
			memcpy_toio(bus->m_pdwSetRing, buf, size);

		} else {
			/* Additional data wraps around the ring */
			memcpy_toio(bus->m_pdwSetRing + curr_swp, msg, sizeof(*msg));
			if (size > 0) {
				memcpy_toio(bus->m_pdwSetRing + curr_swp +
					sizeof(*msg), buf, space_rem -
					sizeof(*msg));
				memcpy_toio(bus->m_pdwSetRing, (u8 *)buf +
					space_rem - sizeof(*msg),
					bytes_to_write - space_rem);
			}

		}

	} /* (new_swp > bus->m_dwSizeSetRing) */
	else {
		dprintk(DBGLVL_BUS, "%s() tr6\n", __func__);

		/* The ring buffer doesn't wrap, two simple copies */
		memcpy_toio(bus->m_pdwSetRing + curr_swp, msg, sizeof(*msg));
		memcpy_toio(bus->m_pdwSetRing + curr_swp + sizeof(*msg), buf,
			size);
	}

	dprintk(DBGLVL_BUS, "%s() new_swp = %x\n", __func__, new_swp);

	/* Update the bus write position */
	saa7164_writel(bus->m_dwSetWritePos, new_swp);

	/* Convert back to cpu after writing the msg to the ringbuffer. */
	msg->size = le16_to_cpu((__force __le16)msg->size);
	msg->command = le32_to_cpu((__force __le32)msg->command);
	msg->controlselector = le16_to_cpu((__force __le16)msg->controlselector);
	ret = SAA_OK;

out:
	saa7164_bus_dump(dev);
	mutex_unlock(&bus->lock);
	saa7164_bus_verify(dev);
	return ret;
}

/*
 * Receive a command or a response from the bus. The implementation does not
 * know if it is a command or a response it simply dequeues the data,
 * depending on the bus information given in the struct tmComResBusInfo
 * structure.
 *
 * Return Value:
 *  0          The function executed successfully.
 *  < 0        One or more members are not initialized.
 */
int saa7164_bus_get(struct saa7164_dev *dev, struct tmComResInfo* msg,
	void *buf, int peekonly)
{
	struct tmComResBusInfo *bus = &dev->bus;
	u32 bytes_to_read, write_distance, curr_grp, curr_gwp,
		new_grp, buf_size, space_rem;
	struct tmComResInfo msg_tmp;
	int ret = SAA_ERR_BAD_PARAMETER;

	saa7164_bus_verify(dev);

	if (msg == NULL)
		return ret;

	if (msg->size > dev->bus.m_wMaxReqSize) {
		printk(KERN_ERR "%s() Exceeded dev->bus.m_wMaxReqSize\n",
			__func__);
		return ret;
	}

	if ((peekonly == 0) && (msg->size > 0) && (buf == NULL)) {
		printk(KERN_ERR
			"%s() Missing msg buf, size should be %d bytes\n",
			__func__, msg->size);
		return ret;
	}

	mutex_lock(&bus->lock);

	/* Peek the bus to see if a msg exists, if it's not what we're expecting
	 * then return cleanly else read the message from the bus.
	 */
	curr_gwp = saa7164_readl(bus->m_dwGetWritePos);
	curr_grp = saa7164_readl(bus->m_dwGetReadPos);

	if (curr_gwp == curr_grp) {
		ret = SAA_ERR_EMPTY;
		goto out;
	}

	bytes_to_read = sizeof(*msg);

	/* Calculate write distance to current read position */
	write_distance = 0;
	if (curr_gwp >= curr_grp)
		/* Write doesn't wrap around the ring */
		write_distance = curr_gwp - curr_grp;
	else
		/* Write wraps around the ring */
		write_distance = curr_gwp + bus->m_dwSizeGetRing - curr_grp;

	if (bytes_to_read > write_distance) {
		printk(KERN_ERR "%s() No message/response found\n", __func__);
		ret = SAA_ERR_INVALID_COMMAND;
		goto out;
	}

	/* Calculate the new read position */
	new_grp = curr_grp + bytes_to_read;
	if (new_grp > bus->m_dwSizeGetRing) {

		/* Ring wraps */
		new_grp -= bus->m_dwSizeGetRing;
		space_rem = bus->m_dwSizeGetRing - curr_grp;

		memcpy_fromio(&msg_tmp, bus->m_pdwGetRing + curr_grp, space_rem);
		memcpy_fromio((u8 *)&msg_tmp + space_rem, bus->m_pdwGetRing,
			bytes_to_read - space_rem);

	} else {
		/* No wrapping */
		memcpy_fromio(&msg_tmp, bus->m_pdwGetRing + curr_grp, bytes_to_read);
	}
	/* Convert from little endian to CPU */
	msg_tmp.size = le16_to_cpu((__force __le16)msg_tmp.size);
	msg_tmp.command = le32_to_cpu((__force __le32)msg_tmp.command);
	msg_tmp.controlselector = le16_to_cpu((__force __le16)msg_tmp.controlselector);
	memcpy(msg, &msg_tmp, sizeof(*msg));

	/* No need to update the read positions, because this was a peek */
	/* If the caller specifically want to peek, return */
	if (peekonly) {
		goto peekout;
	}

	/* Check if the command/response matches what is expected */
	if ((msg_tmp.id != msg->id) || (msg_tmp.command != msg->command) ||
		(msg_tmp.controlselector != msg->controlselector) ||
		(msg_tmp.seqno != msg->seqno) || (msg_tmp.size != msg->size)) {

		printk(KERN_ERR "%s() Unexpected msg miss-match\n", __func__);
		saa7164_bus_dumpmsg(dev, msg, buf);
		saa7164_bus_dumpmsg(dev, &msg_tmp, NULL);
		ret = SAA_ERR_INVALID_COMMAND;
		goto out;
	}

	/* Get the actual command and response from the bus */
	buf_size = msg->size;

	bytes_to_read = sizeof(*msg) + msg->size;
	/* Calculate write distance to current read position */
	write_distance = 0;
	if (curr_gwp >= curr_grp)
		/* Write doesn't wrap around the ring */
		write_distance = curr_gwp - curr_grp;
	else
		/* Write wraps around the ring */
		write_distance = curr_gwp + bus->m_dwSizeGetRing - curr_grp;

	if (bytes_to_read > write_distance) {
		printk(KERN_ERR "%s() Invalid bus state, missing msg or mangled ring, faulty H/W / bad code?\n",
		       __func__);
		ret = SAA_ERR_INVALID_COMMAND;
		goto out;
	}

	/* Calculate the new read position */
	new_grp = curr_grp + bytes_to_read;
	if (new_grp > bus->m_dwSizeGetRing) {

		/* Ring wraps */
		new_grp -= bus->m_dwSizeGetRing;
		space_rem = bus->m_dwSizeGetRing - curr_grp;

		if (space_rem < sizeof(*msg)) {
			if (buf)
				memcpy_fromio(buf, bus->m_pdwGetRing + sizeof(*msg) -
					space_rem, buf_size);

		} else if (space_rem == sizeof(*msg)) {
			if (buf)
				memcpy_fromio(buf, bus->m_pdwGetRing, buf_size);
		} else {
			/* Additional data wraps around the ring */
			if (buf) {
				memcpy_fromio(buf, bus->m_pdwGetRing + curr_grp +
					sizeof(*msg), space_rem - sizeof(*msg));
				memcpy_fromio(buf + space_rem - sizeof(*msg),
					bus->m_pdwGetRing, bytes_to_read -
					space_rem);
			}

		}

	} else {
		/* No wrapping */
		if (buf)
			memcpy_fromio(buf, bus->m_pdwGetRing + curr_grp + sizeof(*msg),
				buf_size);
	}

	/* Update the read positions, adjusting the ring */
	saa7164_writel(bus->m_dwGetReadPos, new_grp);

peekout:
	ret = SAA_OK;
out:
	mutex_unlock(&bus->lock);
	saa7164_bus_verify(dev);
	return ret;
}