pcf8574.c

linux I2C driver for pxa cpu, ov9640 camera. Also include a doc about linux I2C driver

/*
    pcf8574.c - Part of lm_sensors, Linux kernel modules for hardware
             monitoring
    Copyright (c) 2000  Frodo Looijaard <[e-mail]>, 
                        Philip Edelbrock <[e-mail]>,
                        Dan Eaton <[e-mail]>
    Ported to Linux 2.6 by Aurelien Jarno <[e-mail]> with 
    the help of Jean Delvare <[e-mail]>

    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., 675 Mass Ave, Cambridge, MA 02139, USA.
*/

/* A few notes about the PCF8574:

* The PCF8574 is an 8-bit I/O expander for the I2C bus produced by
  Philips Semiconductors.  It is designed to provide a byte I2C
  interface to up to 8 separate devices.
  
* The PCF8574 appears as a very simple SMBus device which can be
  read from or written to with SMBUS byte read/write accesses.

  --Dan

*/

#include <linux/module.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/i2c.h>

/* Addresses to scan */
static unsigned short normal_i2c[] = { 0x2a, 
					I2C_CLIENT_END };
static struct i2c_client *g_client = NULL;
/* Insmod parameters */
I2C_CLIENT_INSMOD_2(pcf8574, pcf8574a);

/* Initial values */
#define PCF8574_INIT 255	/* All outputs on (input mode) */

/* Each client has this additional data */
struct pcf8574_data {
	struct i2c_client client;

	u8 write;			/* Remember last written value */
};

static int pcf8574_attach_adapter(struct i2c_adapter *adapter);
static int pcf8574_detect(struct i2c_adapter *adapter, int address, int kind);
static int pcf8574_detach_client(struct i2c_client *client);
static void pcf8574_init_client(struct i2c_client *client);

/* This is the driver that will be inserted */
static struct i2c_driver pcf8574_driver = {
	.driver = {
		.name	= "pcf8574",
	},
	.id		= I2C_DRIVERID_PCF8574,
	.attach_adapter	= pcf8574_attach_adapter,
	.detach_client	= pcf8574_detach_client,
};

/* following are the sysfs callback functions */
static ssize_t show_read(struct device *dev, struct device_attribute *attr, char *buf)
{
	struct i2c_client *client = to_i2c_client(dev);
	return sprintf(buf, "%u\n", i2c_smbus_read_byte(client));
}

static DEVICE_ATTR(read, S_IRUGO, show_read, NULL);

static ssize_t show_write(struct device *dev, struct device_attribute *attr, char *buf)
{
	struct pcf8574_data *data = i2c_get_clientdata(to_i2c_client(dev));
	return sprintf(buf, "%u\n", data->write);
}

static ssize_t set_write(struct device *dev, struct device_attribute *attr, const char *buf,
			 size_t count)
{
	struct i2c_client *client = to_i2c_client(dev);
	struct pcf8574_data *data = i2c_get_clientdata(client);
	unsigned long val = simple_strtoul(buf, NULL, 10);

	if (val > 0xff)
		return -EINVAL;

	data->write = val;
	i2c_smbus_write_byte(client, data->write);
	return count;
}

static DEVICE_ATTR(write, S_IWUSR | S_IRUGO, show_write, set_write);

/*
 * Real code
 */

static int pcf8574_attach_adapter(struct i2c_adapter *adapter)
{
	return i2c_probe(adapter, &addr_data, pcf8574_detect);
}
#if 0
int pcf8574_read(u8 addr, u8 value)
{
	int	res=0;
	

	char 	buf=value;
printk("%s\n",__FUNCTION__);

if( g_client == NULL )
		return -1;
	res = i2c_master_recv(g_client, &buf, 1);
	if (res >0) 
		res =0;
	else 
		res =-1;
	printk(KERN_INFO "In funtion %s addr:%x value:%xreturn %d \n", __FUNCTION__, addr,value,res);
	return res;
}
#endif
#if 1

int pcf8574_read(u8 addr, u8 *pvalue)
{   

    //printk("%s\n",__FUNCTION__);


    int res=0;

    char   buf=0;

    char buffer=0x0;

    struct i2c_msg msgs[1] ={

     // { addr, 0, 1, &buffer },

       { addr, 1, 1, &buf }};

 printk("%s\n",__FUNCTION__);

    if( g_client == NULL )   

       return -1;

//  i2c_ov9640_inc_use(g_client);

   // msgs[0].addr=msgs[1].addr=g_client->addr;

//msgs[0].addr=g_client->addr;
    //res=i2c_transfer(g_client->adapter,&msgs[0],1);

    //if (res<=0) 

      // goto out;

    res=i2c_transfer(g_client->adapter,msgs,1);

    if (res<=0) 

       goto out;
	

  //  printk("%s--buf value=%x\n",__FUNCTION__, buf);

    *pvalue=buf;

 

    printk("%s-- pvalue=%x\n",__FUNCTION__,*pvalue);

    return buf;

//  i2c_ov9640_dec_use(g_client);

out:

    printk(KERN_INFO "In funtion %s addr:%x,value=%x\n", __FUNCTION__, addr,*pvalue);

    if (res<=0) printk("res = %d \n",res);

    return res;

}

#endif

int pcf8574_write(u8 addr, u8 value)
{
	int	res=0;
	printk("%s\n",__FUNCTION__);
	if( g_client == NULL )
		return -1;

	char 	buffer[1]={value};

struct i2c_msg msgs[1] = 

       { addr, 0, 1, &buffer[0] };

	   res=i2c_transfer(g_client->adapter,msgs,1);

    if (res<=0) 

       goto out;

	
	//res = i2c_master_send(g_client, buf, 2);
	//if (res >0) 
	//	res =0;
	//else 
	//	res =-1;
	printk(KERN_INFO "In funtion %s addr:%x value:%xreturn %d \n", __FUNCTION__, addr,value,res);
	return res;


	out:

    printk(KERN_INFO "In funtion %s addr:%x,value=%x\n", __FUNCTION__, addr,value);

    if (res<=0) printk("res = %d \n",res);

    return res;
}	

/* This function is called by i2c_probe */
static int pcf8574_detect(struct i2c_adapter *adapter, int address, int kind)
{
	struct i2c_client *new_client;
	struct pcf8574_data *data;
	int err = 0;
	const char *client_name = "";

	if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE))
		goto exit;

	/* OK. For now, we presume we have a valid client. We now create the
	   client structure, even though we cannot fill it completely yet. */
	if (!(data = kzalloc(sizeof(struct pcf8574_data), GFP_KERNEL))) {
		err = -ENOMEM;
		goto exit;
	}

	new_client = &data->client;
	i2c_set_clientdata(new_client, data);
	new_client->addr = address;
	new_client->adapter = adapter;
	new_client->driver = &pcf8574_driver;
	new_client->flags = 0;
g_client=new_client;
	/* Now, we would do the remaining detection. But the PCF8574 is plainly
	   impossible to detect! Stupid chip. */

	/* Determine the chip type */
	if (kind <= 0) {
		if (address >= 0x38 && address <= 0x3f)
			kind = pcf8574a;
		else
			kind = pcf8574;
	}

	if (kind == pcf8574a)
		client_name = "pcf8574a";
	else
		client_name = "pcf8574";

	/* Fill in the remaining client fields and put it into the global list */
	strlcpy(new_client->name, client_name, I2C_NAME_SIZE);

	/* Tell the I2C layer a new client has arrived */
	if ((err = i2c_attach_client(new_client)))
		{printk("pcf8574 cpld has been registered failed!\n");goto exit_free;}
		else{printk("pcf8574 cpld has been registered success!\n");}
	
	/* Initialize the PCF8574 chip */
	pcf8574_init_client(new_client);

	/* Register sysfs hooks */
	device_create_file(&new_client->dev, &dev_attr_read);
	device_create_file(&new_client->dev, &dev_attr_write);
	return 0;

/* OK, this is not exactly good programming practice, usually. But it is
   very code-efficient in this case. */

      exit_free:
	kfree(data);
      exit:
	return err;
}

static int pcf8574_detach_client(struct i2c_client *client)
{
	int err;

	if ((err = i2c_detach_client(client)))
		return err;

	kfree(i2c_get_clientdata(client));
	return 0;
}

/* Called when we have found a new PCF8574. */
static void pcf8574_init_client(struct i2c_client *client)
{
	struct pcf8574_data *data = i2c_get_clientdata(client);
	data->write =0x0;// PCF8574_INIT;
	i2c_smbus_write_byte(client, data->write);
}

static int __init pcf8574_init(void)
{
    int res=0;

if ( (res = i2c_add_driver(&pcf8574_driver)) ) {
		printk("pcf8574: Driver registration failed, module not inserted.\n");
		i2c_del_driver(&pcf8574_driver);
		return res;
	}

     if(g_client != NULL)
   	   printk("I2C: driver for device %s registed!.\n", g_client->name);
        else 
           printk("I2C: driver for device unregisted!.\n");
}

static void __exit pcf8574_exit(void)
{
	i2c_del_driver(&pcf8574_driver);
}


MODULE_AUTHOR
    ("Frodo Looijaard <[e-mail]>, "
     "Philip Edelbrock <[e-mail]>, "
     "Dan Eaton <[e-mail]> "
     "and Aurelien Jarno <[e-mail]>");
MODULE_DESCRIPTION("PCF8574 driver");
MODULE_LICENSE("GPL");

EXPORT_SYMBOL(pcf8574_write);
EXPORT_SYMBOL(pcf8574_read);
module_init(pcf8574_init);
module_exit(pcf8574_exit);