[PARPORT] i2c

Philip Blundell (philb@gnu.org)
Wed, 04 Nov 1998 19:36:19 +0100

I forget who was asking for it, but...

Here's the IIC driver I wrote to run over a parallel port. It's a pretty
trivial piece of code as you can see. :-)

p.

/*
 * I2C driver for 4-wire parallel port
 */

#include <linux/parport.h>
#include <linux/module.h>
#include <linux/delay.h>
#include <linux/i2c.h>

#define I2C_DELAY 10

/* software I2C functions */

static void i2c_setlines(struct i2c_bus *bus,int ctrl,int data)
{
  struct parport *p = bus->data;
  parport_write_data(p, (ctrl?1:0) | (data?2:0));
  udelay(I2C_DELAY);
}

static int i2c_getdataline(struct i2c_bus *bus)
{
  struct parport *p = bus->data;
  return ((parport_read_status(p) & 0x80) >> 7) ^ 1;
}

static struct i2c_bus p4w_i2c_bus_template =
{
  "p4w",
  I2C_BUSID_P4W,
  NULL,
  
  SPIN_LOCK_UNLOCKED,
  
  NULL,
  NULL,
        
  i2c_setlines,
  i2c_getdataline,
  NULL,
  NULL,
};

#define MAX_BUS 8

static int nr_bus = 0;

static struct i2c_bus *bus[MAX_BUS];
 
int init_module(void)
{
  struct parport *p = parport_enumerate();
  while (p)
  {
    struct i2c_bus *b = kmalloc(sizeof(struct i2c_bus), GFP_KERNEL);
    *b = p4w_i2c_bus_template;
    b->data = p;
    i2c_register_bus(b);
    bus[nr_bus++] = b;
    if (nr_bus == MAX_BUS) break;
    p = p->next;
  }
  return 0;
}

void cleanup_module(void)
{
  int i;
  for (i = 0; i < nr_bus; i++)
    i2c_unregister_bus(bus[i]);
}

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This archive was generated by hypermail 2.0b3 on Wed 30 Dec 1998 - 10:18:44 EST