On Tue, Feb 10, 2009 at 11:52 AM, Daniel Baluta <daniel.baluta@xxxxxxxxx> wrote:
> On Mon, Feb 9, 2009 at 9:45 PM, Greg KH <greg@xxxxxxxxx> wrote:
>> On Mon, Feb 09, 2009 at 09:23:47PM +0200, Daniel Baluta wrote:
>>> On Mon, Feb 9, 2009 at 7:56 PM, Daniel Baluta <daniel.baluta@xxxxxxxxx> wrote:
>>> > On Mon, Feb 9, 2009 at 7:19 PM, Greg KH <greg@xxxxxxxxx> wrote:
>>> >> On Mon, Feb 09, 2009 at 06:43:51PM +0200, Daniel Baluta wrote:
>>> >>> On Mon, Feb 9, 2009 at 12:20 AM, Greg KH <greg@xxxxxxxxx> wrote:
>>> >>> > On Sun, Feb 08, 2009 at 07:47:05PM +0200, Daniel Baluta wrote:
>>> >>> >> Hello,
>>> >>> >>
>>> >>> >> I don't really understand how kernel generates events when working
>>> >>> >> with platform devices and drivers ( [1] ).
>>> >>> >> I have registered my driver with platform_driver_register and my
>>> >>> >> device with platform_device_register_simple.
>>> >>> >>
>>> >>> >> I want to dynamically create the node in /dev , and for that i need
>>> >>> >> the kernel to send events like ( MAJOR=x, MINOR=y)
>>> >>> >> that will be interpreted by the udev daemon acording to rules from
>>> >>> >> /etc/udev/rules.d.
>>> >>> >
>>> >>> > Platform devices can't do this, you need to use a "real" struct device,
>>> >>> > or register with a class that handles major/minor allocation for you
>>> >>> > (input, block, etc.)
>>> >>> >
>>> >>> > hope this helps,
>>> >>> >
>>> >>> > greg k-h
>>> >>> >
>>> >>>
>>> >>> thanks for your answer.
>>> >>>
>>> >>> I'm writing a driver for a character device [hex display] .
>>> >>>
>>> >>> Registering with an existing class its pretty hard since it doesn't
>>> >>> fit well in none of the existing classes.
>>> >>
>>> >> There are other drivers in the kernel that already do something like
>>> >> this, are you sure there isn't an existing class for you already?
>>> >>
>>> >
>>> > I'm still searching for it. Any suggestion , it's welcomed.
>>
>> I know one staging driver supports it, and I think a few different USB
>> ones do as well. Have you looked at the LED class? That might be what
>> I was thinking of.
>>
>>> >>> One good option would be misc class but this enforces the usage of major 10.
>>> >>
>>> >> What's wrong with that? It's a dynamic minor number that will "just
>>> >> work" for your device.
>>> >>
>>> > Yes , you are right here it's "just working". But I have some requirements
>>> > that ask for major to be dynamically allocated.
>>
>> What kind of requirement would require something like that? Do you
>> really need to support 16k different devices? Hm, even with that kind
>> of requirement, the misc interface would still work just fine.
>>
>> Have a pointer to your code anywhere?
>>
>> thanks,
>>
>> greg k-h
>>
>
> Hello ,
>
> Led class seems to be a very good idea.
>
> You can find below a snippet of my reworked code:
>
>
> static struct led_classdev hex_classdev = {
> .name = "hexclass",
> };
>
> static int my_probe(struct platform_device *pdev)
> {
> int ret;
>
> ret = led_classdev_register(&pdev->dev, &hex_classdev);
> if (ret < 0)
> return ret;
> printk("led_classdev_register called in probe!\n");
> return ret;
> }
>
> static int my_remove(struct platform_device *pdev)
> {
> led_classdev_unregister(&hex_classdev);
> printk("led_clasdev_unregister called in remove\n");
>
> return 0;
> }
>
>
> static struct platform_driver my_driver = {
> .probe = my_probe,
> .remove = my_remove,
> .driver = {
> .name = "led",
> .owner = THIS_MODULE,
> },
> };
>
> static struct platform_device *my_device;
> static int __init my_init(void)
> {
>
> my_device = platform_device_register_simple("led", -1 , NULL, 0);
>
> return platform_driver_register(&my_driver);
> }
>
> static void __exit my_exit(void)
> {
>
> platform_device_unregister(my_device);
> platform_driver_unregister(&my_driver);
> }
>
>
> The idea is that i want to dynamically create /dev/hexd in order to
> write to my hexdisplay.
> So i need to send an event like MAJOR=x, MINOR=y to udev and this
> should do mknod /dev/hexd c MAJOR MINOR.
>
> I've noticed that for example , for printer class there is a file
> /sys/class/printer/lp0/dev that contains MAJOR:MINOR.
>
> When i run my code there is no /sys/class/leds/hexclass/dev file created.
> Could this be the problem? Is there any special function that must be called.
>
>
> Thanks,
> Daniel.
>
Ok , so it seems that /sys/class/leds/hexclass/dev is not created
because of this function call chain:
led_classdev_register
- device_create_drvdata(led_class, parent , 0 , ... )
The third parameter should be a dev_t containing major and minor but
is 0 , so no /hexclass/dev file is created.
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