f32xbase/f32x/c2-bitbang.c

/*
 * f32x/c2-bitbang.c - Basic C2 messages, bitbang
 *
 * Written 2008, 2010 by Werner Almesberger
 * Copyright 2008, 2010 Werner Almesberger
 *
 * 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 file is meant to be #included by a .c file that defines C2CK and C2D,
 * provides the gpio_* functions, etc.
 */


#include <stdint.h>
#include <unistd.h>


/* ----- Bit-level operations ---------------------------------------------- */


static void c2_pulse(void)
{
	gpio_low(C2CK);
	gpio_high(C2CK);
}


static void c2_send(uint32_t value, int bits)
{
	int i;

	for (i = 0; i != bits; i++) {
		gpio_set(C2D, (value >> i) & 1);
		c2_pulse();
	}
}


static uint32_t c2_recv(int bits)
{
	uint32_t v = 0;
	int i;

	for (i = 0; i != bits; i++) {
		v |= gpio_get(C2D) << i;
		c2_pulse();
    	}
	return v;
}


/* ----- C2 Register read/write -------------------------------------------- */


static void c2_addr_write(uint8_t addr)
{
	c2_pulse();
	gpio_output(C2D);
	c2_send(C2_ADDR_WRITE, 2);
	c2_send(addr, 8);
	gpio_input(C2D);
	c2_pulse();
}


static uint8_t c2_addr_read(void)
{
	c2_pulse();
	gpio_output(C2D);
	c2_send(C2_ADDR_READ, 2);
	gpio_input(C2D);
	c2_pulse();
	return c2_recv(8);
}


static void c2_data_write(uint32_t data, int bytes)
{
	c2_pulse();
	gpio_output(C2D);
	c2_send(C2_DATA_WRITE, 2);
	c2_send(bytes-1, 2);
	c2_send(data, 8*bytes);
	gpio_input(C2D);
	c2_pulse();
	while (!c2_recv(1));
}


static uint32_t c2_data_read(int bytes)
{
	c2_pulse();
	gpio_output(C2D);
	c2_send(C2_DATA_READ, 2);
	c2_send(bytes-1, 2);
	gpio_input(C2D);
	c2_pulse();
	while (!c2_recv(1));
	return c2_recv(8*bytes);
}


/* ----- C2 initialization ------------------------------------------------- */


static void c2_init(void)
{
	gpio_input(C2D);
	gpio_output(C2CK);
	gpio_low(C2CK);
	usleep(20);
	gpio_high(C2CK);
	usleep(2);
}


static void c2_reset(void)
{
	gpio_input(C2D);
	gpio_low(C2CK);
	usleep(20);
//	gpio_input(C2CK);
	gpio_output(C2CK);
	gpio_high(C2CK);
}