/*
    Nios-sim - one simple NIOSII simulator only for personal interest and fun.
    Copyright (C) 2010  chysun2000@gmail.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.

    You should have received a copy of the GNU General Public License along
    with this program; if not, write to the Free Software Foundation, Inc.,
    51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/

#include <stdio.h>
#include <string.h>

#include "public.h"
#include "jtag_uart.h"

static struct jtag_uart_priv priv;
static void uart_init(struct io_device * self)
{
	memset(&priv, 0x00, sizeof(struct jtag_uart_priv));

	if (self != NULL){
		self->priv_data = &priv;
		priv.regs[JTAG_UART_DATA_REG].addr = JTAG_UART_BASE_ADDR;
		priv.regs[JTAG_UART_CTRL_REG].addr = JTAG_UART_BASE_ADDR + 4;
		/* init control register */
		priv.regs[JTAG_UART_CTRL_REG].value = (JTAG_UART_FIFO_SIZE) << ALTERA_JTAGUART_CONTROL_WSPACE_OFST; /* FIFO is empty */
	}
	
	printf("Jtag UART at 0x%08x\n",JTAG_UART_BASE_ADDR);
}

static int32_t uart_is_belong(uint32_t address)
{
	int32_t i = 0;
	
	for (i=0;i<JTAG_UART_REG_COUNT;i++){
		if (priv.regs[i].addr == address){
			return ADDR_IS_DEV;
		}
	}
	return ADDR_IS_NOT_DEV;
} 

static uint32_t uart_read(struct io_device * self, uint32_t addr, uint32_t data_len)
{
	if (addr == priv.regs[JTAG_UART_CTRL_REG].addr){
		return priv.regs[JTAG_UART_CTRL_REG].value;
	}
	else if (addr == priv.regs[JTAG_UART_DATA_REG].addr){
		return priv.regs[JTAG_UART_DATA_REG].value;
	}

	return 0;
}

static void write_tx_fifo(uint32_t data)
{
	priv.tx_fifo.data = data & 0xFF;
	priv.tx_fifo.is_write = 1;
	/* clean WI bit */
	priv.regs[JTAG_UART_CTRL_REG].value &= (~ALTERA_JTAGUART_CONTROL_WI_MSK);
	/* clean write space bits */
	priv.regs[JTAG_UART_CTRL_REG].value &= 0xFFFF;
}

static void uart_write(struct io_device * self, uint32_t addr, uint32_t data, uint32_t data_len)
{
	int32_t i = 0;
	
    for (i=0;i<JTAG_UART_REG_COUNT;i++){
        if (priv.regs[i].addr == addr){
			if (i == JTAG_UART_DATA_REG){
				priv.regs[i].value = io_write_data(priv.regs[i].value, data, data_len);
				write_tx_fifo(data);
			}
			else if(i == JTAG_UART_CTRL_REG){
				priv.regs[i].value |= (io_write_data(priv.regs[i].value, data, data_len) & 0x3);
				/* if change the interrupt enable bits */
				if (data & 0x03){
					priv.regs[i].value = priv.regs[i].value & (~ALTERA_JTAGUART_CONTROL_WI_MSK);
				}
			}
        }
    }
}

static uint32_t jtag_trans_clk = 500;
static int32_t jtag_uart_has_irq(struct io_device * self)
{
	int32_t ret_val = DEV_NO_IRQ;
	uint32_t reg_ctrl_val = priv.regs[JTAG_UART_CTRL_REG].value;

	if (jtag_trans_clk > 0){
		jtag_trans_clk --;
		return ret_val;
	}
	else {
		jtag_trans_clk = 500;
	}
	
	/* handle TX write fifo empty interrupt */
	if (reg_ctrl_val & ALTERA_JTAGUART_CONTROL_WE_MSK){
		if ((reg_ctrl_val & ALTERA_JTAGUART_CONTROL_WSPACE_MSK) != 0){
			ret_val = DEV_HAS_IRQ;
		}
	}
	
#if 0	
	/* handle RX data available interrupt */
	if (reg_ctrl_val & ALTERA_JTAGUART_CONTROL_RE_MSK){
		if (reg_ctrl_val & ALTERA_JTAGUART_DATA_RVALID_MSK){
			ret_val = DEV_HAS_IRQ;
			priv.regs[JTAG_UART_CTRL_REG].value |= ALTERA_JTAGUART_CONTROL_RI_MSK;
		}
		else{
			priv.regs[JTAG_UART_CTRL_REG].value &= (~ALTERA_JTAGUART_CONTROL_RI_MSK);
		}
	}
#endif
	return ret_val;
}

static void jtag_uart_simulate(struct io_device * self)
{	
	/* if has data to send */
	if (priv.tx_fifo.is_write){
		printf("%c", priv.tx_fifo.data);
		priv.tx_fifo.is_write = 0;
		/* set available fifo size */
		priv.regs[JTAG_UART_CTRL_REG].value |= (JTAG_UART_FIFO_SIZE << ALTERA_JTAGUART_CONTROL_WSPACE_OFST);
		/* if set write interrupt enable */
		if (priv.regs[JTAG_UART_CTRL_REG].value & ALTERA_JTAGUART_CONTROL_WE_MSK){
			/* set write interrupt bit */
			priv.regs[JTAG_UART_CTRL_REG].value |= ALTERA_JTAGUART_CONTROL_WI_MSK;
		}
	}
	else {
		if (priv.regs[JTAG_UART_CTRL_REG].value & (JTAG_UART_FIFO_SIZE << ALTERA_JTAGUART_CONTROL_WSPACE_OFST)){
			/* if set write interrupt enable */
			if (priv.regs[JTAG_UART_CTRL_REG].value & ALTERA_JTAGUART_CONTROL_WE_MSK){
				/* set write interrupt bit */
				priv.regs[JTAG_UART_CTRL_REG].value |= ALTERA_JTAGUART_CONTROL_WI_MSK;
			}
		}
	}
}

struct io_device jtag_uart_io_device = {
	.name = "Jtag UART Core",
	.init = uart_init,
	.is_belong = uart_is_belong,
	.read_data = uart_read,
	.write_data = uart_write,
	.has_irq = jtag_uart_has_irq,
	.simulate = jtag_uart_simulate,
	.irq_enable_mask = JTAG_IRQ_MASK
};