Commit f3b3aadb authored by Jean Delvare's avatar Jean Delvare Committed by Greg Kroah-Hartman
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i2c-dev: Use a list for data storage 



i2c-dev: Use a list for data storage

Use a list instead of a static array for storing the i2c-dev data.
Given that most systems have less than 10 i2c busses, most of the
space was wasted, so this saves around 1 kB of memory (2 kB on 64-bit
archs.)

The drawback is that lookup was in O(1) and is now in O(N), but given
that the values of N are always small, I don't think this is a problem.

Signed-off-by: default avatarJean Delvare <khali@linux-fr.org>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@suse.de>
parent 9455e4c9

drivers/i2c/i2c-dev.c

+25 −20
Original line number Original line Diff line number Diff line
@@ -32,6 +32,7 @@ 
#include <linux/slab.h>

#include <linux/slab.h>

#include <linux/smp_lock.h>

#include <linux/smp_lock.h>

#include <linux/init.h>

#include <linux/init.h>

#include <linux/list.h>

#include <linux/i2c.h>

#include <linux/i2c.h>

#include <linux/i2c-dev.h>

#include <linux/i2c-dev.h>

#include <asm/uaccess.h>

#include <asm/uaccess.h>
@@ -39,21 +40,27 @@ 
static struct i2c_client i2cdev_client_template;

static struct i2c_client i2cdev_client_template;





struct i2c_dev {

struct i2c_dev {

	struct list_head list;

	struct i2c_adapter *adap;

	struct i2c_adapter *adap;

	struct class_device *class_dev;

	struct class_device *class_dev;

};

};





#define I2C_MINORS	256

#define I2C_MINORS	256

static struct i2c_dev *i2c_dev_array[I2C_MINORS];

static LIST_HEAD(i2c_dev_list);

static DEFINE_SPINLOCK(i2c_dev_array_lock);

static DEFINE_SPINLOCK(i2c_dev_list_lock);





static struct i2c_dev *i2c_dev_get_by_minor(unsigned index)

static struct i2c_dev *i2c_dev_get_by_minor(unsigned index)

{

{

	struct i2c_dev *i2c_dev;

	struct i2c_dev *i2c_dev;





	spin_lock(&i2c_dev_array_lock);

	spin_lock(&i2c_dev_list_lock);

	i2c_dev = i2c_dev_array[index];

	list_for_each_entry(i2c_dev, &i2c_dev_list, list) {

	spin_unlock(&i2c_dev_array_lock);

		if (i2c_dev->adap->nr == index)

			goto found;

	}

	i2c_dev = NULL;

found:

	spin_unlock(&i2c_dev_list_lock);

	return i2c_dev;

	return i2c_dev;

}

}
@@ -61,30 +68,28 @@ static struct i2c_dev *get_free_i2c_dev(struct i2c_adapter *adap) 
{

{

	struct i2c_dev *i2c_dev;

	struct i2c_dev *i2c_dev;





	if (adap->nr >= I2C_MINORS) {

		printk(KERN_ERR "i2c-dev: Out of device minors (%d)\n",

		       adap->nr);

		return ERR_PTR(-ENODEV);

	}



	i2c_dev = kzalloc(sizeof(*i2c_dev), GFP_KERNEL);

	i2c_dev = kzalloc(sizeof(*i2c_dev), GFP_KERNEL);

	if (!i2c_dev)

	if (!i2c_dev)

		return ERR_PTR(-ENOMEM);

		return ERR_PTR(-ENOMEM);



	spin_lock(&i2c_dev_array_lock);

	if (i2c_dev_array[adap->nr]) {

		spin_unlock(&i2c_dev_array_lock);

		dev_err(&adap->dev, "i2c-dev already has a device assigned to this adapter\n");

		goto error;

	}

	i2c_dev->adap = adap;

	i2c_dev->adap = adap;

	i2c_dev_array[adap->nr] = i2c_dev;



	spin_unlock(&i2c_dev_array_lock);

	spin_lock(&i2c_dev_list_lock);

	list_add_tail(&i2c_dev->list, &i2c_dev_list);

	spin_unlock(&i2c_dev_list_lock);

	return i2c_dev;

	return i2c_dev;

error:

	kfree(i2c_dev);

	return ERR_PTR(-ENODEV);

}

}





static void return_i2c_dev(struct i2c_dev *i2c_dev)

static void return_i2c_dev(struct i2c_dev *i2c_dev)

{

{

	spin_lock(&i2c_dev_array_lock);

	spin_lock(&i2c_dev_list_lock);

	i2c_dev_array[i2c_dev->adap->nr] = NULL;

	list_del(&i2c_dev->list);

	spin_unlock(&i2c_dev_array_lock);

	spin_unlock(&i2c_dev_list_lock);

}

}





static ssize_t show_adapter_name(struct class_device *class_dev, char *buf)

static ssize_t show_adapter_name(struct class_device *class_dev, char *buf)

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