/*
    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 "public.h"
#include "niosii.h"
#include "io_device.h"
#include "uart_core.h"

#define REG_RXDATA (0)
#define REG_TXDATA (1)
#define REG_STATUS (2)
#define REG_CONTROL (3)
#define REG_DIVISOR (4)
#define REG_ENDOFPACKET (5)

static struct uart_core_hw hw;
static uint32_t valid_mask[UART_CORE_REG_CNT] = {
	0x1FF,0x1FF,0x1FFF,0x1FFF,0xFFFF,0x1FF
};

static uint32_t only_read_mask[UART_CORE_REG_CNT] = {
	0x1FF,0x00,0x00,0x00,0x00,0x00
};
	
static void uart_init(struct io_device * self)
{
	int32_t i = 0;
	
	self->priv_data = &hw;
	for (i=0;i<UART_CORE_REG_CNT; i++){
		hw.io_regs[i].addr = UART_CORE_BASE_ADDR + i * 4;
		hw.io_regs[i].value = 0;
		hw.io_regs[i].valid_mask = valid_mask[i];
		hw.io_regs[i].only_read_mask = only_read_mask[i];
	}
	
	hw.rx_status = 0;
	hw.tx_status = 0;
	printf("%s at 0x%08X-0x%08X\n",self->name, UART_CORE_BASE_ADDR, UART_CORE_BASE_ADDR + i * 4 - 4);
}

static int32_t uart_is_belong(uint32_t address)
{
	int32_t ret_val = ADDR_IS_NOT_DEV;
	
	if ((address >= UART_CORE_BASE_ADDR) && (address < (UART_CORE_BASE_ADDR + UART_CORE_REG_CNT * 4))){
		ret_val = ADDR_IS_DEV;
	}
	return ret_val;
}

static uint32_t uart_read(struct io_device * self, uint32_t addr, uint32_t data_len)
{
	uint32_t ret_val = 0;
	uint32_t index = 0;
	
	index = (addr - UART_CORE_BASE_ADDR) / 4;
	if (index >= 0 && index < UART_CORE_REG_CNT){
		ret_val = hw.io_regs[index].value & hw.io_regs[index].valid_mask;
		ret_val = io_read_data(ret_val, data_len);
		
		if (index == REG_RXDATA){
			hw.rx_status = UART_HAS_NO_DATA_TO_RX;
			hw.io_regs[REG_STATUS].value &= (~ALTERA_UART_STATUS_RRDY_MSK);
		}
	}
	return ret_val;
}

static void uart_write(struct io_device * self, uint32_t addr, uint32_t data, uint32_t data_len)
{
	uint32_t index = 0;
	uint32_t temp = 0;
	uint32_t only_read_mask = 0;
	uint32_t valid_mask = 0;
	
	index = (addr - UART_CORE_BASE_ADDR) / 4;
	
	if (index >= 0 && index < UART_CORE_REG_CNT){
		temp = hw.io_regs[index].value;
		valid_mask = hw.io_regs[index].valid_mask;
		only_read_mask = hw.io_regs[index].only_read_mask;
		hw.io_regs[index].value = io_write_data_mask(temp, data, data_len, valid_mask, only_read_mask);
		if(index == REG_TXDATA){
			hw.tx_status = UART_HAS_DATA_TO_TX;
			hw.io_regs[REG_STATUS].value &= (~ALTERA_UART_STATUS_TRDY_MSK);
		}
	}
}

static int32_t uart_has_irq(struct io_device * self)
{
	int32_t ret_val = DEV_NO_IRQ;
	uint32_t reg_ctrl_val = hw.io_regs[REG_CONTROL].value;
	uint32_t reg_status_val = hw.io_regs[REG_STATUS].value;
	
	/* Check TX ready Interrupt */
	if (check_reg_bit(reg_ctrl_val, ALTERA_UART_CONTROL_TRDY_MSK) == SIM_TRUE){
		if (check_reg_bit(reg_status_val, ALTERA_UART_STATUS_TRDY_MSK) == SIM_TRUE){
			ret_val = DEV_HAS_IRQ;
		}
	}
	
	/* Check RX ready Interrupt */
	if (check_reg_bit(reg_ctrl_val, ALTERA_UART_CONTROL_RRDY_MSK) == SIM_TRUE){
		if (check_reg_bit(reg_status_val, ALTERA_UART_STATUS_RRDY_MSK) == SIM_TRUE){
			ret_val = DEV_HAS_IRQ;
		}
	}
	
	return ret_val;
}

static void uart_simulate(struct io_device * self)
{
	/* handler TX */
	if (hw.tx_status == UART_HAS_DATA_TO_TX){
		hw.io_regs[REG_STATUS].value &= (~ALTERA_UART_STATUS_TRDY_MSK);
		hw.tx_status = UART_HAS_NO_DATA_TO_TX;
		/* Set status TRDY bit */
		hw.io_regs[REG_STATUS].value |= ALTERA_UART_STATUS_TRDY_MSK;
	}
	/* handler RX */
	if(hw.rx_status == UART_HAS_NO_DATA_TO_RX){
		/* ToDo: Get the input data */
		hw.rx_status = UART_HAS_DATA_TO_RX;
		/* Set status RRDY bit */
		hw.io_regs[REG_STATUS].value |= ALTERA_UART_STATUS_RRDY_MSK;
	}
}

struct io_device uart_core = {
	.name = "UART Core",
	.init = uart_init,
	.is_belong = uart_is_belong,
	.read_data = uart_read,
	.write_data = uart_write,
	.has_irq = uart_has_irq,
	.simulate = uart_simulate,
	.irq_enable_mask = UART_IRQ_MASK,
};