iic.c

嵌入式linux的IIC驱动

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/slab.h>
#include <linux/proc_fs.h>
#include <linux/config.h>

#include <linux/i2c.h>

/* ----- compatibility stuff ----------------------------------------------- */

#include <linux/version.h>
#include <linux/init.h>

#if LINUX_VERSION_CODE < KERNEL_VERSION(2,3,1)
#define init_MUTEX(s) do { *(s) = MUTEX; } while(0)
#endif

#include <asm/uaccess.h>

/* ----- global defines ---------------------------------------------------- */

/* exclusive access to the bus */
#define I2C_LOCK(adap) down(&adap->lock)
#define I2C_UNLOCK(adap) up(&adap->lock) 

#define ADAP_LOCK()	down(&adap_lock)
#define ADAP_UNLOCK()	up(&adap_lock)

#define DRV_LOCK()	down(&driver_lock)
#define DRV_UNLOCK()	up(&driver_lock)

#define DEB(x) if (i2c_debug>=1) x;
#define DEB2(x) if (i2c_debug>=2) x;

/* ----- global variables -------------------------------------------------- */

/**** lock for writing to global variables: the adapter & driver list */
struct semaphore adap_lock;
struct semaphore driver_lock;

/**** adapter list */
static struct i2c_adapter *adapters[I2C_ADAP_MAX];
static int adap_count;

/**** drivers list */
static struct i2c_driver *drivers[I2C_DRIVER_MAX];
static int driver_count;

/**** debug level */
static int i2c_debug = 0;

/* ---------------------------------------------------
 * /proc entry declarations
 *----------------------------------------------------
 */

#ifdef CONFIG_PROC_FS

static int i2cproc_init(void);
static void i2cproc_cleanup(void);

#if (LINUX_VERSION_CODE <= KERNEL_VERSION(2,3,27))
static void monitor_bus_i2c(struct inode *inode, int fill);
#endif /* (LINUX_VERSION_CODE >= KERNEL_VERSION(2,1,58)) */

static ssize_t i2cproc_bus_read(struct file * file, char * buf,size_t count, 
                                loff_t *ppos);
static int read_bus_i2c(char *buf, char **start, off_t offset, int len,
                           int *eof , void *private);

/* To implement the dynamic /proc/bus/i2c-? files, we need our own 
   implementation of the read hook */
static struct file_operations i2cproc_operations = {
	read:		i2cproc_bus_read,
};

#if (LINUX_VERSION_CODE < KERNEL_VERSION(2,3,48))
static struct inode_operations i2cproc_inode_operations = {
	&i2cproc_operations
};
#endif

static int i2cproc_initialized = 0;

#else /* undef CONFIG_PROC_FS */

#define i2cproc_init() 0
#define i2cproc_cleanup() 0

#endif /* CONFIG_PROC_FS */


/* ---------------------------------------------------
 * registering functions 
 * --------------------------------------------------- 
 */

/* -----
 * i2c_add_adapter is called from within the algorithm layer,
 * when a new hw adapter registers. A new device is register to be
 * available for clients.
 */
int i2c_add_adapter(struct i2c_adapter *adap)
{
	int i,j,res;

	ADAP_LOCK();
	for (i = 0; i < I2C_ADAP_MAX; i++)
		if (NULL == adapters[i])
			break;
	if (I2C_ADAP_MAX == i) {
		printk(KERN_WARNING 
		       " i2c-core.o: register_adapter(%s) - enlarge I2C_ADAP_MAX.\n",
			adap->name);
		res = -ENOMEM;
		goto ERROR0;
	}

	adapters[i] = adap;
	adap_count++;
	ADAP_UNLOCK();
	
	/* init data types */
	init_MUTEX(&adap->lock);

#ifdef CONFIG_PROC_FS

	if (i2cproc_initialized) {
		char name[8];
		struct proc_dir_entry *proc_entry;

		sprintf(name,"i2c-%d", i);

		proc_entry = create_proc_entry(name,0,proc_bus);
		if (! proc_entry) {
			printk("i2c-core.o: Could not create /proc/bus/%s\n",
			       name);
			res = -ENOENT;
			goto ERROR1;
		}

#if (LINUX_VERSION_CODE >= KERNEL_VERSION(2,3,48))
		proc_entry->proc_fops = &i2cproc_operations;
#else
		proc_entry->ops = &i2cproc_inode_operations;
#endif
#if (LINUX_VERSION_CODE >= KERNEL_VERSION(2,3,27))
		proc_entry->owner = THIS_MODULE;
#else
		proc_entry->fill_inode = &monitor_bus_i2c;
#endif /* (LINUX_VERSION_CODE >= KERNEL_VERSION(2,1,58)) */
		adap->inode = proc_entry->low_ino;
	}

#endif /* def CONFIG_PROC_FS */

	/* inform drivers of new adapters */
	DRV_LOCK();	
	for (j=0;j<I2C_DRIVER_MAX;j++)
		if (drivers[j]!=NULL && 
		    (drivers[j]->flags&(I2C_DF_NOTIFY|I2C_DF_DUMMY)))
			/* We ignore the return code; if it fails, too bad */
			drivers[j]->attach_adapter(adap);
	DRV_UNLOCK();
	
	DEB(printk("i2c-core.o: adapter %s registered as adapter %d.\n",
	           adap->name,i));

	return 0;	


ERROR1:
	ADAP_LOCK();
	adapters[i] = NULL;
	adap_count--;
ERROR0:
	ADAP_UNLOCK();
	return res;
}


int i2c_del_adapter(struct i2c_adapter *adap)
{
	int i,j,res;

	ADAP_LOCK();

	for (i = 0; i < I2C_ADAP_MAX; i++)
		if (adap == adapters[i])
			break;
	if (I2C_ADAP_MAX == i) {
		printk( "i2c-core.o: unregister_adapter adap [%s] not found.\n",
			adap->name);
		res = -ENODEV;
		goto ERROR0;
	}

	/* DUMMY drivers do not register their clients, so we have to
	 * use a trick here: we call driver->attach_adapter to
	 * *detach* it! Of course, each dummy driver should know about
	 * this or hell will break loose...
	 */
	DRV_LOCK();
	for (j = 0; j < I2C_DRIVER_MAX; j++) 
		if (drivers[j] && (drivers[j]->flags & I2C_DF_DUMMY))
			if ((res = drivers[j]->attach_adapter(adap))) {
				printk("i2c-core.o: can't detach adapter %s "
				       "while detaching driver %s: driver not "
				       "detached!",adap->name,drivers[j]->name);
				goto ERROR1;	
			}
	DRV_UNLOCK();


	/* detach any active clients. This must be done first, because
	 * it can fail; in which case we give upp. */
	for (j=0;j<I2C_CLIENT_MAX;j++) {
		struct i2c_client *client = adap->clients[j];
		if (client!=NULL)
		    /* detaching devices is unconditional of the set notify
		     * flag, as _all_ clients that reside on the adapter
		     * must be deleted, as this would cause invalid states.
		     */
			if ((res=client->driver->detach_client(client))) {
				printk("i2c-core.o: adapter %s not "
					"unregistered, because client at "
					"address %02x can't be detached. ",
					adap->name, client->addr);
				goto ERROR0;
			}
	}
#ifdef CONFIG_PROC_FS
	if (i2cproc_initialized) {
		char name[8];
		sprintf(name,"i2c-%d", i);
		remove_proc_entry(name,proc_bus);
	}
#endif /* def CONFIG_PROC_FS */

	adapters[i] = NULL;
	adap_count--;
	
	ADAP_UNLOCK();	
	DEB(printk("i2c-core.o: adapter unregistered: %s\n",adap->name));
	return 0;

ERROR0:
	ADAP_UNLOCK();
	return res;
ERROR1:
	DRV_UNLOCK();
	return res;
}


/* -----
 * What follows is the "upwards" interface: commands for talking to clients,
 * which implement the functions to access the physical information of the
 * chips.
 */

int i2c_add_driver(struct i2c_driver *driver)
{
	int i;
	DRV_LOCK();
	for (i = 0; i < I2C_DRIVER_MAX; i++)
		if (NULL == drivers[i])
			break;
	if (I2C_DRIVER_MAX == i) {
		printk(KERN_WARNING 
		       " i2c-core.o: register_driver(%s) "
		       "- enlarge I2C_DRIVER_MAX.\n",
			driver->name);
		DRV_UNLOCK();
		return -ENOMEM;
	}

	drivers[i] = driver;
	driver_count++;
	
	DRV_UNLOCK();	/* driver was successfully added */
	
	DEB(printk("i2c-core.o: driver %s registered.\n",driver->name));
	
	ADAP_LOCK();

	/* now look for instances of driver on our adapters
	 */
	if (driver->flags& (I2C_DF_NOTIFY|I2C_DF_DUMMY)) {
		for (i=0;i<I2C_ADAP_MAX;i++)
			if (adapters[i]!=NULL)
				/* Ignore errors */
				driver->attach_adapter(adapters[i]);
	}
	ADAP_UNLOCK();
	return 0;
}

int i2c_del_driver(struct i2c_driver *driver)
{
	int i,j,k,res;

	DRV_LOCK();
	for (i = 0; i < I2C_DRIVER_MAX; i++)
		if (driver == drivers[i])
			break;
	if (I2C_DRIVER_MAX == i) {
		printk(KERN_WARNING " i2c-core.o: unregister_driver: "
				    "[%s] not found\n",
			driver->name);
		DRV_UNLOCK();
		return -ENODEV;
	}
	/* Have a look at each adapter, if clients of this driver are still
	 * attached. If so, detach them to be able to kill the driver 
	 * afterwards.
	 */
	DEB2(printk("i2c-core.o: unregister_driver - looking for clients.\n"));
	/* removing clients does not depend on the notify flag, else 
	 * invalid operation might (will!) result, when using stale client
	 * pointers.
	 */
	ADAP_LOCK(); /* should be moved inside the if statement... */
	for (k=0;k<I2C_ADAP_MAX;k++) {
		struct i2c_adapter *adap = adapters[k];
		if (adap == NULL) /* skip empty entries. */
			continue;
		DEB2(printk("i2c-core.o: examining adapter %s:\n",
			    adap->name));
		if (driver->flags & I2C_DF_DUMMY) {
		/* DUMMY drivers do not register their clients, so we have to
		 * use a trick here: we call driver->attach_adapter to
		 * *detach* it! Of course, each dummy driver should know about
		 * this or hell will break loose...  
		 */
			if ((res = driver->attach_adapter(adap))) {
				printk("i2c-core.o: while unregistering "
				       "dummy driver %s, adapter %s could "
				       "not be detached properly; driver "
				       "not unloaded!",driver->name,
				       adap->name);
				ADAP_UNLOCK();
				return res;
			}
		} else {
			for (j=0;j<I2C_CLIENT_MAX;j++) { 
				struct i2c_client *client = adap->clients[j];
				if (client != NULL && 
				    client->driver == driver) {
					DEB2(printk("i2c-core.o: "
						    "detaching client %s:\n",
					            client->name));
					if ((res = driver->
							detach_client(client)))
					{
						printk("i2c-core.o: while "
						       "unregistering driver "
						       "`%s', the client at "
						       "address %02x of
						       adapter `%s' could not
						       be detached; driver
						       not unloaded!",
						       driver->name,
						       client->addr,
						       adap->name);
						ADAP_UNLOCK();
						return res;
					}
				}
			}
		}
	}
	ADAP_UNLOCK();
	drivers[i] = NULL;
	driver_count--;
	DRV_UNLOCK();
	
	DEB(printk("i2c-core.o: driver unregistered: %s\n",driver->name));
	return 0;
}

int i2c_check_addr (struct i2c_adapter *adapter, int addr)
{
	int i;
	for (i = 0; i < I2C_CLIENT_MAX ; i++) 
		if (adapter->clients[i] && (adapter->clients[i]->addr == addr))
			return -EBUSY;
	return 0;
}

int i2c_attach_client(struct i2c_client *client)
{
	struct i2c_adapter *adapter = client->adapter;
	int i;

	if (i2c_check_addr(client->adapter,client->addr))
		return -EBUSY;

	for (i = 0; i < I2C_CLIENT_MAX; i++)
		if (NULL == adapter->clients[i])
			break;
	if (I2C_CLIENT_MAX == i) {
		printk(KERN_WARNING 
		       " i2c-core.o: attach_client(%s) - enlarge I2C_CLIENT_MAX.\n",
			client->name);
		return -ENOMEM;
	}

	adapter->clients[i] = client;
	adapter->client_count++;
	
	if (adapter->client_register) 
		if (adapter->client_register(client)) 
			printk("i2c-core.o: warning: client_register seems "
			       "to have failed for client %02x at adapter %s\n",
			       client->addr,adapter->name);
	DEB(printk("i2c-core.o: client [%s] registered to adapter [%s](pos. %d).\n",
		client->name, adapter->name,i));

	if(client->flags & I2C_CLIENT_ALLOW_USE)
		client->usage_count = 0;
	
	return 0;
}


int i2c_detach_client(struct i2c_client *client)
{
	struct i2c_adapter *adapter = client->adapter;
	int i,res;

	for (i = 0; i < I2C_CLIENT_MAX; i++)