/*
 * Copyright (c) 2007 Michal Konopa
 * Copyright (c) 2007 Martin Jelen
 * Copyright (c) 2007 Peter Majer
 * Copyright (c) 2007 Jakub Jermar
 * All rights reserved.
 *
 * 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.
 * - The name of the author may not be used to endorse or promote products
 *   derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 AUTHOR 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.
 */

/** @addtogroup rd
 * @{
 */ 

/**
 * @file	rd.c
 * @brief	Initial RAM disk for HelenOS.
 */

#include <ipc/ipc.h>
#include <ipc/services.h>
#include <ipc/ns.h>
#include <sysinfo.h>
#include <as.h>
#include <ddi.h>
#include <align.h>
#include <bool.h>
#include <errno.h>
#include <async.h>
#include <align.h>
#include <async.h>
#include <futex.h>
#include "rd.h"

/** Pointer to the ramdisk's image. */
static void *rd_addr;
/** Size of the ramdisk. */
static size_t rd_size;

/**
 * This futex protects the ramdisk's data.
 * If we were to serve multiple requests (read + write or several writes)
 * concurrently (i.e. from two or more threads), each read and write needs to be
 * protected by this futex.
 */ 
atomic_t rd_futex = FUTEX_INITIALIZER;

/** Handle one connection to ramdisk.
 *
 * @param iid		Hash of the request that opened the connection.
 * @param icall		Call data of the request that opened the connection.
 */
static void rd_connection(ipc_callid_t iid, ipc_call_t *icall)
{
	ipc_callid_t callid;
	ipc_call_t call;
	int retval;
	void *fs_va = NULL;
	ipcarg_t offset;

	/*
	 * We allocate VA for communication per connection.
	 * This allows us to potentionally have more clients and work
	 * concurrently.
	 */
	fs_va = as_get_mappable_page(ALIGN_UP(BLOCK_SIZE, PAGE_SIZE));
	if (!fs_va) {
		/*
		 * Hang up the phone if we cannot proceed any further.
		 * This is the answer to the call that opened the connection.
		 */
		ipc_answer_0(iid, EHANGUP);
		return;
	} else {
		/*
		 * Answer the first IPC_M_CONNECT_ME_TO call.
		 * Return supported block size as ARG1.
		 */
		ipc_answer_1(iid, EOK, BLOCK_SIZE);
	}

	/*
	 * Now we wait for the client to send us its communication as_area.
	 */
	size_t size;
	if (ipc_share_out_receive(&callid, &size, NULL)) {
		if (size >= BLOCK_SIZE) {
			/*
			 * The client sends an as_area that can absorb the whole
			 * block.
			 */
			(void) ipc_share_out_finalize(callid, fs_va);
		} else {
			/*
			 * The client offered as_area too small.
			 * Close the connection.
			 */
			ipc_answer_0(callid, EHANGUP);
			return;		
		}
	} else {
		/*
		 * The client doesn't speak the same protocol.
		 * At this point we can't handle protocol variations.
		 * Close the connection.
		 */
		ipc_answer_0(callid, EHANGUP);
		return;
	}
	
	while (1) {
		callid = async_get_call(&call);
		switch (IPC_GET_METHOD(call)) {
		case IPC_M_PHONE_HUNGUP:
			/*
			 * The other side has hung up.
			 * Answer the message and exit the fibril.
			 */
			ipc_answer_0(callid, EOK);
			return;
		case RD_READ_BLOCK:
			offset = IPC_GET_ARG1(call);
			if (offset * BLOCK_SIZE > rd_size - BLOCK_SIZE) {
				/*
				 * Reading past the end of the device.
				 */
				retval = ELIMIT;
				break;
			}
			futex_down(&rd_futex);
			memcpy(fs_va, rd_addr + offset, BLOCK_SIZE);
			futex_up(&rd_futex);
			retval = EOK;
			break;
		case RD_WRITE_BLOCK:
			offset = IPC_GET_ARG1(call);
			if (offset * BLOCK_SIZE > rd_size - BLOCK_SIZE) {
				/*
				 * Writing past the end of the device.
				 */
				retval = ELIMIT;
				break;
			}
			futex_up(&rd_futex);
			memcpy(rd_addr + offset, fs_va, BLOCK_SIZE);
			futex_down(&rd_futex);
			retval = EOK;
			break;
		default:
			/*
			 * The client doesn't speak the same protocol.
			 * Instead of closing the connection, we just ignore
			 * the call. This can be useful if the client uses a
			 * newer version of the protocol.
			 */
			retval = EINVAL;
			break;
		}
		ipc_answer_0(callid, retval);
	}
}

/** Prepare the ramdisk image for operation. */
static bool rd_init(void)
{
	int retval, flags;

	rd_size = sysinfo_value("rd.size");
	void *rd_ph_addr = (void *) sysinfo_value("rd.address.physical");
	
	if (rd_size == 0)
		return false;
	
	rd_addr = as_get_mappable_page(rd_size);
	
	flags = AS_AREA_READ | AS_AREA_WRITE | AS_AREA_CACHEABLE;
	retval = physmem_map(rd_ph_addr, rd_addr,
	    ALIGN_UP(rd_size, PAGE_SIZE) >> PAGE_WIDTH, flags);

	if (retval < 0)
		return false;
	return true;
}

int main(int argc, char **argv)
{
	if (rd_init()) {
		ipcarg_t phonead;
		
		async_set_client_connection(rd_connection);
		
		/* Register service at nameserver */
		if (ipc_connect_to_me(PHONE_NS, SERVICE_RD, 0, 0, &phonead) != 0)
			return -1;
		
		async_manager();
		
		/* Never reached */
		return 0;
	}
	
	return -1;
}

/**
 * @}
 */