Hi Everybody,

I have a question, on using the available i2c-gpio driver in linux kernel.
If I do a lsmod I can see the loaded driver, but can't see any relevant devie nod in /dev directory.It has been registered as platform driver.

How can I access this driver from user space.?
If I need to create a /dev node, then how can I get the major no.?

I am attaching the driver for your review.

Any help will be appreciated.

Many thanks, betz


/*********************************/

struct i2c_s3c2410_bit {
struct i2c_adapter adap;
struct i2c_algo_bit_data algo;
};

static void i2c_s3c2410_bit_setsda(void *data, int state)
{
if (state)
s3c2410_gpio_cfgpin(S3C2410_GPD8, S3C2410_GPIO_INPUT);
else
{
s3c2410_gpio_setpin(S3C2410_GPD8, 0);
s3c2410_gpio_cfgpin(S3C2410_GPD8, S3C2410_GPIO_OUTPUT);
}
}

static void i2c_s3c2410_bit_setscl(void *data, int state)
{
if (state)
s3c2410_gpio_cfgpin(S3C2410_GPD9, S3C2410_GPIO_INPUT);
else
{
s3c2410_gpio_setpin(S3C2410_GPD9, 0);
s3c2410_gpio_cfgpin(S3C2410_GPD9, S3C2410_GPIO_OUTPUT);
}
}

static int i2c_s3c2410_bit_getsda(void *data)
{
return !!s3c2410_gpio_getpin(S3C2410_GPD8);
}

static int i2c_s3c2410_bit_getscl(void *data)
{
return !!s3c2410_gpio_getpin(S3C2410_GPD9);
}

static struct i2c_algo_bit_data i2c_s3c2410_bit_algo = {
.setsda = i2c_s3c2410_bit_setsda,
.setscl = i2c_s3c2410_bit_setscl,
.getsda = i2c_s3c2410_bit_getsda,
.getscl = i2c_s3c2410_bit_getscl,
.udelay = 100,
.timeout = HZ,
};

static int i2c_s3c2410_bit_probe(struct platform_device *dev)
{
// printk("%s\n", __FUNCTION__);
struct i2c_s3c2410_bit *i2c;
int ret;

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

i2c = kzalloc(sizeof(struct i2c_s3c2410_bit), GFP_KERNEL);
if (!i2c) {
ret = -ENOMEM;
goto err_out;
}

s3c2410_gpio_cfgpin(S3C2410_GPD9, S3C2410_GPIO_INPUT);
s3c2410_gpio_cfgpin(S3C2410_GPD8, S3C2410_GPIO_INPUT);

i2c->adap.owner = THIS_MODULE;
strlcpy(i2c->adap.name, "S3C2410 bit-bang I2C adapter", sizeof(i2c->adap.name));
i2c->adap.algo_data = &i2c->algo;
i2c->adap.dev.parent = &dev->dev;
i2c->algo = i2c_s3c2410_bit_algo;
i2c->algo.data = i2c;

ret = i2c_bit_add_bus(&i2c->adap);
if (ret >= 0) {
platform_set_drvdata(dev, i2c);
return 0;
}

kfree(i2c);
err_out:
return ret;
}

static int i2c_s3c2410_bit_remove(struct platform_device *dev)
{
struct i2c_s3c2410_bit *i2c = platform_get_drvdata(dev);

platform_set_drvdata(dev, NULL);

i2c_del_adapter(&i2c->adap);
return 0;
}

static struct platform_driver i2c_s3c2410_bit_driver = {
.probe = i2c_s3c2410_bit_probe,
.remove = i2c_s3c2410_bit_remove,
.driver = {
.name = "s3c2410-i2c-bit",
.owner = THIS_MODULE,
},
};

static int __init i2c_s3c2410_bit_init(void)
{

return platform_driver_register(&i2c_s3c2410_bit_driver);
}

static void __exit i2c_s3c2410_bit_exit(void)
{

platform_driver_unregister(&i2c_s3c2410_bit_driver);
}

module_init(i2c_s3c2410_bit_init);
module_exit(i2c_s3c2410_bit_exit);

MODULE_DESCRIPTION("S3C2410 bit-bang I2C bus driver");
MODULE_LICENSE("GPL");

/*********************************/

That driver is intended as a helper for other drivers that want to access the GPIO pins (through the kernel's generic GPIO library).

To access the GPIO pins from user space, write your own driver, or enable the CONFIG_GPIO_SYSFS option and use the sysfs files.