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/*
 *   Generic i2c interface for linux
 *
 *   (c) 1998 Gerd Knorr <kraxel@cs.tu-berlin.de>
 *
 */

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/types.h>
#include <linux/string.h>
#include <linux/delay.h>
#include <linux/locks.h>
#include <linux/sched.h>
#include <linux/malloc.h>

#include "i2c.h"

#define REGPRINT(x)   if (verbose)   (x)
#define I2C_DEBUG(x)  if (i2c_debug) (x)

static int scan      = 0;
static int verbose   = 1;
static int i2c_debug = 0;
#if LINUX_VERSION_CODE >= 0x020117
MODULE_PARM(scan,"i");
MODULE_PARM(verbose,"i");
MODULE_PARM(i2c_debug,"i");
#endif

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

static struct i2c_bus    *busses[I2C_BUS_MAX];
static struct i2c_driver *drivers[I2C_DRIVER_MAX];
static int bus_count = 0, driver_count = 0;

int i2c_init(void)
{
    printk(KERN_INFO "i2c: initialized%s\n",
	   scan ? " (i2c bus scan enabled)" : "");
    /* anything to do here ? */
    return 0;
}

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

static void i2c_attach_device(struct i2c_bus *bus, struct i2c_driver *driver)
{
    unsigned long flags;
    struct i2c_device *device;
    int i,j,ack=1;
    unsigned char addr;
    
    /* probe for device */
    LOCK_I2C_BUS(bus);
    for (addr = driver->addr_l; addr <= driver->addr_h; addr += 2) {
	i2c_start(bus);
	ack = i2c_sendbyte(bus,addr,0);
	i2c_stop(bus);
	if (!ack)
	    break;
    }
    UNLOCK_I2C_BUS(bus);
    if (ack)
	return;

    /* got answer */
    for (i = 0; i < I2C_DEVICE_MAX; i++)
	if (NULL == driver->devices[i])
	    break;
    if (I2C_DEVICE_MAX == i)
	return;

    for (j = 0; j < I2C_DEVICE_MAX; j++)
	if (NULL == bus->devices[j])
	    break;
    if (I2C_DEVICE_MAX == j)
	return;

    if (NULL == (device = kmalloc(sizeof(struct i2c_device),GFP_KERNEL)))
	return;
    device->bus = bus;
    device->driver = driver;
    device->addr = addr;

    /* attach */
    if (0 != driver->attach(device)) {
	kfree(device);
	return;
    }
    driver->devices[i] = device;
    driver->devcount++;
    bus->devices[j] = device;
    bus->devcount++;

    if (bus->attach_inform)
	bus->attach_inform(bus,driver->id);
    REGPRINT(printk("i2c: device attached: %s (addr=0x%02x, bus=%s, driver=%s)\n",device->name,addr,bus->name,driver->name));
}

static void i2c_detach_device(struct i2c_device *device)
{
    int i;

    if (device->bus->detach_inform)
	device->bus->detach_inform(device->bus,device->driver->id);
    device->driver->detach(device);

    for (i = 0; i < I2C_DEVICE_MAX; i++)
	if (device == device->driver->devices[i])
	    break;
    if (I2C_DEVICE_MAX == i) {
	printk(KERN_WARNING "i2c: detach_device #1: device not found: %s\n",
	       device->name);
	return;
    }
    device->driver->devices[i] = NULL;
    device->driver->devcount--;

    for (i = 0; i < I2C_DEVICE_MAX; i++)
	if (device == device->bus->devices[i])
	    break;
    if (I2C_DEVICE_MAX == i) {
	printk(KERN_WARNING "i2c: detach_device #2: device not found: %s\n",
	       device->name);
	return;
    }
    device->bus->devices[i] = NULL;
    device->bus->devcount--;

    REGPRINT(printk("i2c: device detached: %s (addr=0x%02x, bus=%s, driver=%s)\n",device->name,device->addr,device->bus->name,device->driver->name));
    kfree(device);
}

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

int i2c_register_bus(struct i2c_bus *bus)
{
    unsigned long flags;
    int i,ack;

    memset(bus->devices,0,sizeof(bus->devices));
    bus->devcount = 0;

    for (i = 0; i < I2C_BUS_MAX; i++)
	if (NULL == busses[i])
	    break;
    if (I2C_BUS_MAX == i)
	return -ENOMEM;

    busses[i] = bus;
    bus_count++;
    REGPRINT(printk("i2c: bus registered: %s\n",bus->name));

    LOCK_I2C_BUS(bus);
    i2c_reset(bus);
    if (scan) {
	/* scan whole i2c bus */
	for (i = 0; i < 256; i+=2) {
	    i2c_start(bus);
	    ack = i2c_sendbyte(bus,i,0);
	    i2c_stop(bus);
	    if (!ack) {
		printk("i2c: scanning bus %s: found device at addr=0x%02x\n",
		       bus->name,i);
	    }
	}
    }
    UNLOCK_I2C_BUS(bus);

    /* probe available drivers */
    for (i = 0; i < I2C_DRIVER_MAX; i++)
	if (drivers[i])
	    i2c_attach_device(bus,drivers[i]);

    return 0;
}

int i2c_unregister_bus(struct i2c_bus *bus)
{
    int i;

    /* detach devices */
    for (i = 0; i < I2C_DEVICE_MAX; i++)
	if (bus->devices[i])
	    i2c_detach_device(bus->devices[i]);

    for (i = 0; i < I2C_BUS_MAX; i++)
	if (bus == busses[i])
	    break;
    if (I2C_BUS_MAX == i) {
	printk(KERN_WARNING "i2c: unregister_bus #1: bus not found: %s\n",
	       bus->name);
	return -ENODEV;
    }

    busses[i] = NULL;
    bus_count--;
    REGPRINT(printk("i2c: bus unregistered: %s\n",bus->name));

    return 0;    
}

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

int i2c_register_driver(struct i2c_driver *driver)
{
    int i;

    memset(driver->devices,0,sizeof(driver->devices));
    driver->devcount = 0;

    for (i = 0; i < I2C_DRIVER_MAX; i++)
	if (NULL == drivers[i])
	    break;
    if (I2C_DRIVER_MAX == i)
	return -ENOMEM;

    drivers[i] = driver;
    driver_count++;
    REGPRINT(printk("i2c: driver registered: %s\n",driver->name));

    /* probe available busses */
    for (i = 0; i < I2C_BUS_MAX; i++)
	if (busses[i])
	    i2c_attach_device(busses[i],driver);

    return 0;
}

int i2c_unregister_driver(struct i2c_driver *driver)
{
    int i;

    /* detach devices */
    for (i = 0; i < I2C_DEVICE_MAX; i++)
	if (driver->devices[i])
	    i2c_detach_device(driver->devices[i]);

    for (i = 0; i < I2C_DRIVER_MAX; i++)
	if (driver == drivers[i])
	    break;
    if (I2C_DRIVER_MAX == i) {
	printk(KERN_WARNING "i2c: unregister_driver: driver not found: %s\n",
	       driver->name);
	return -ENODEV;
    }

    drivers[i] = NULL;
    driver_count--;
    REGPRINT(printk("i2c: driver unregistered: %s\n",driver->name));

    return 0;
}

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

int i2c_control_device(struct i2c_bus *bus, int id,
		       unsigned int cmd, void *arg)
{
    int i;

    for (i = 0; i < I2C_DEVICE_MAX; i++)
	if (bus->devices[i] && bus->devices[i]->driver->id == id)
	    break;
    if (i == I2C_DEVICE_MAX)
	return -ENODEV;
    if (NULL == bus->devices[i]->driver->command)
	return -ENODEV;
    return bus->devices[i]->driver->command(bus->devices[i],cmd,arg);
}

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

#define I2C_SET(bus,ctrl,data)  (bus->i2c_setlines(bus,ctrl,data))
#define I2C_GET(bus)            (bus->i2c_getdataline(bus))

void i2c_reset(struct i2c_bus *bus)
{
    I2C_SET(bus,1,1);
    I2C_DEBUG(printk("%s: bus reset",bus->name));
}

void i2c_start(struct i2c_bus *bus)
{
    I2C_SET(bus,0,1);
    I2C_SET(bus,1,1);
    I2C_SET(bus,1,0);
    I2C_SET(bus,0,0);
    I2C_DEBUG(printk("%s: < ",bus->name));
}

void i2c_stop(struct i2c_bus *bus)
{
    I2C_SET(bus,0,0);
    I2C_SET(bus,1,0);
    I2C_SET(bus,1,1);
    I2C_DEBUG(printk(">\n"));
}

void i2c_one(struct i2c_bus *bus)
{
    I2C_SET(bus,0,1);
    I2C_SET(bus,1,1);
    I2C_SET(bus,0,1);
}

void i2c_zero(struct i2c_bus *bus)
{
    I2C_SET(bus,0,0);
    I2C_SET(bus,1,0);
    I2C_SET(bus,0,0);
}

int i2c_ack(struct i2c_bus *bus)
{
    int ack;
    
    I2C_SET(bus,0,1);
    I2C_SET(bus,1,1);
    ack = I2C_GET(bus);
    I2C_SET(bus,0,1);
    return ack;
}

int i2c_sendbyte(struct i2c_bus *bus,unsigned char data,int wait_for_ack)
{
    int i, ack;
    
    I2C_SET(bus,0,0);
    for (i=7; i>=0; i--)
	(data&(1<<i)) ? i2c_one(bus) : i2c_zero(bus);
    if (wait_for_ack)
	udelay(wait_for_ack);
    ack=i2c_ack(bus);
    I2C_DEBUG(printk("%02x%c ",(int)data,ack?'-':'+'));
    return ack;
}

unsigned char i2c_readbyte(struct i2c_bus *bus,int last)
{
    int i;
    unsigned char data=0;
    
    I2C_SET(bus,0,1);
    for (i=7; i>=0; i--) {
	I2C_SET(bus,1,1);
	if (I2C_GET(bus))
	    data |= (1<<i);
	I2C_SET(bus,0,1);
    }
    last ? i2c_one(bus) : i2c_zero(bus);
    I2C_DEBUG(printk("=%02x%c ",(int)data,last?'-':'+'));
    return data;
}

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

int i2c_read(struct i2c_bus *bus, unsigned char addr)
{
    int ret;
    
    if (bus->i2c_read)
	return bus->i2c_read(bus, addr);

    i2c_start(bus);
    i2c_sendbyte(bus,addr,0);
    ret = i2c_readbyte(bus,1);
    i2c_stop(bus);
    return ret;
}

int i2c_write(struct i2c_bus *bus, unsigned char addr,
	      unsigned char data1, unsigned char data2, int both)
{
    int ack;

    if (bus->i2c_write)
	return bus->i2c_write(bus, addr, data1, data2, both);

    i2c_start(bus);
    i2c_sendbyte(bus,addr,0);
    ack = i2c_sendbyte(bus,data1,0);
    if (both)
	ack = i2c_sendbyte(bus,data2,0);
    i2c_stop(bus);
    return ack ? -1 : 0 ;
}

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

#ifdef MODULE

#if LINUX_VERSION_CODE >= 0x020100
EXPORT_SYMBOL(i2c_register_bus);
EXPORT_SYMBOL(i2c_unregister_bus);
EXPORT_SYMBOL(i2c_register_driver);
EXPORT_SYMBOL(i2c_unregister_driver);
EXPORT_SYMBOL(i2c_control_device);
EXPORT_SYMBOL(i2c_reset);
EXPORT_SYMBOL(i2c_start);
EXPORT_SYMBOL(i2c_stop);
EXPORT_SYMBOL(i2c_one);
EXPORT_SYMBOL(i2c_zero);
EXPORT_SYMBOL(i2c_ack);
EXPORT_SYMBOL(i2c_sendbyte);
EXPORT_SYMBOL(i2c_readbyte);
EXPORT_SYMBOL(i2c_read);
EXPORT_SYMBOL(i2c_write);
#endif

int init_module(void)
{
    return i2c_init();
}

void cleanup_module(void)
{
}

#endif

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