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: Jean Delvare <khali@linux-fr.org> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This commit is contained in:
parent
9455e4c9ab
commit
f3b3aadbbd
|
@ -32,6 +32,7 @@
|
|||
#include <linux/slab.h>
|
||||
#include <linux/smp_lock.h>
|
||||
#include <linux/init.h>
|
||||
#include <linux/list.h>
|
||||
#include <linux/i2c.h>
|
||||
#include <linux/i2c-dev.h>
|
||||
#include <asm/uaccess.h>
|
||||
|
@ -39,21 +40,27 @@
|
|||
static struct i2c_client i2cdev_client_template;
|
||||
|
||||
struct i2c_dev {
|
||||
struct list_head list;
|
||||
struct i2c_adapter *adap;
|
||||
struct class_device *class_dev;
|
||||
};
|
||||
|
||||
#define I2C_MINORS 256
|
||||
static struct i2c_dev *i2c_dev_array[I2C_MINORS];
|
||||
static DEFINE_SPINLOCK(i2c_dev_array_lock);
|
||||
static LIST_HEAD(i2c_dev_list);
|
||||
static DEFINE_SPINLOCK(i2c_dev_list_lock);
|
||||
|
||||
static struct i2c_dev *i2c_dev_get_by_minor(unsigned index)
|
||||
{
|
||||
struct i2c_dev *i2c_dev;
|
||||
|
||||
spin_lock(&i2c_dev_array_lock);
|
||||
i2c_dev = i2c_dev_array[index];
|
||||
spin_unlock(&i2c_dev_array_lock);
|
||||
spin_lock(&i2c_dev_list_lock);
|
||||
list_for_each_entry(i2c_dev, &i2c_dev_list, list) {
|
||||
if (i2c_dev->adap->nr == index)
|
||||
goto found;
|
||||
}
|
||||
i2c_dev = NULL;
|
||||
found:
|
||||
spin_unlock(&i2c_dev_list_lock);
|
||||
return i2c_dev;
|
||||
}
|
||||
|
||||
|
@ -61,30 +68,28 @@ static struct i2c_dev *get_free_i2c_dev(struct i2c_adapter *adap)
|
|||
{
|
||||
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);
|
||||
if (!i2c_dev)
|
||||
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_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;
|
||||
error:
|
||||
kfree(i2c_dev);
|
||||
return ERR_PTR(-ENODEV);
|
||||
}
|
||||
|
||||
static void return_i2c_dev(struct i2c_dev *i2c_dev)
|
||||
{
|
||||
spin_lock(&i2c_dev_array_lock);
|
||||
i2c_dev_array[i2c_dev->adap->nr] = NULL;
|
||||
spin_unlock(&i2c_dev_array_lock);
|
||||
spin_lock(&i2c_dev_list_lock);
|
||||
list_del(&i2c_dev->list);
|
||||
spin_unlock(&i2c_dev_list_lock);
|
||||
}
|
||||
|
||||
static ssize_t show_adapter_name(struct class_device *class_dev, char *buf)
|
||||
|
|
Loading…
Reference in a new issue