/********************************************************************\

  Name:         gpio.c
  Created by:   Stefan Ritt

  Contents:     Driver for MCP23S17 General Purpose IO Chip

\********************************************************************/
      
#include <stdio.h>
#include <string.h>
#include <intrins.h>
#include <stdlib.h>
#include "mscbemb.h"
#include "spi.h"

// register addresses for non-banked layout (bank=0)
#define GPIO_IODIRA    0x00
#define GPIO_IODIRB    0x01
#define GPIO_IPOLA     0x02
#define GPIO_IPOLB     0x03
#define GPIO_GPINTENA  0x04
#define GPIO_GPINTENB  0x05
#define GPIO_DEFVALA   0x06
#define GPIO_DEFVALB   0x07
#define GPIO_INTCONA   0x08
#define GPIO_INTCONB   0x09
#define GPIO_IOCON     0x0A
#define GPIO_GPPUA     0x0C
#define GPIO_GPPUB     0x0D
#define GPIO_INTFA     0x0E
#define GPIO_INTFB     0x0F
#define GPIO_INTCAPA   0x10
#define GPIO_INTCAPB   0x11
#define GPIO_GPIOA     0x12
#define GPIO_GPIOB     0x13
#define GPIO_OLATA     0x14
#define GPIO_OLATB     0x15

/*------------------------------------------------------------------*/

sbit RST_SR       = P1 ^ 2;

void gpio_write(unsigned char device, unsigned char adr, unsigned char d);
void spi_write_msb(unsigned char d);

void gpio_init()
{
   // remove RST_SR
   SFRPAGE = LEGACY_PAGE;
   RST_SR  = 1;

   gpio_write(0, GPIO_IOCON, 1<<3);     // HAEN = 1, addresses all four devices
   gpio_write(0, GPIO_IODIRA, 0);       // all output
   gpio_write(0, GPIO_IODIRB, 0);

   gpio_write(1, GPIO_IOCON, 1<<3);     // HAEN = 1, addresses all four devices
   gpio_write(1, GPIO_IODIRA, 0xFF);    // all input
   gpio_write(1, GPIO_IODIRB, 0xFF);
}

/*------------------------------------------------------------------*/

void gpio_write(unsigned char device, unsigned char adr, unsigned char d)
{
   spi_adr();
   
   // Device opcode 0x40 combined with 3-bit hardware address, R/W = 0 (=write)
   spi_write_msb(0x40 | ((device & 0x07) << 1));
   spi_write_msb(adr);  
   spi_write_msb(d);  
   spi_deadr();
}

/*------------------------------------------------------------------*/

void gpio_out(unsigned short d)
{
   gpio_write(0, GPIO_OLATA, d & 0xff);
   gpio_write(0, GPIO_OLATB, d >> 8);
}

/*------------------------------------------------------------------*/

unsigned char gpio_read(unsigned char device, unsigned char adr)
{
   unsigned char d;

   // Device opcode 0x40 combined 3-bit hardware address, R/W = 1 (=read)
   spi_adr();
   spi_write_msb(0x40 | ((device & 0x07) << 1) | 0x01);
   spi_write_msb(adr);  
   d = spi_read_msb();  
   spi_deadr();
   
   return d;
}

/*------------------------------------------------------------------*/


unsigned short gpio_in()
{
   unsigned short d;
   
   d = gpio_read(1, GPIO_GPIOA) | (gpio_read(1, GPIO_GPIOB) << 8);  
   return d;
}