> virtual-devices {
> compatible = "simple-bus";
> dsa {
> compatible = "<vendor>,jkc5200n8-dsa";
> };
> };
Ok, after correcting the names, the basic OF driver is probed.
Now to try and use probe to register the DSA platform driver with the
OF driver as its parent.
=======
For those interested in how to get a very basic OF (uses FDT) driver
going, the steps I did are below.
'myvendor' is your company name, and 'mydevice' is the name of the
device - use better names in real code.
(1) The .dts file - this is the Flattened Device Tree (FDT)
descriptor:
/ {
...
virtual-device {
compatible = "simple-bus";
mydevice0 {
compatible = "myvendor,mydevice";
};
};
...
};
For my board "simple-bus" is an already defined bus in the .dts.
In my case the .dts had:
/ {
...
localbus {
compatible =
"fsl,mpc5200b-lpb","fsl,mpc5200-lpb","simple-bus";
...
};
...
};
(2) Create the OF driver:
#include <linux/of.h>
#include <linux/kernel.h>
#include <linux/of_platform.h>
static int __devinit mydevice_probe(struct of_device *ofdev, const
struct of_device_id *match)
{
printk("mydevice_probe\n");
return 0;
}
static int mydevice_remove(struct of_device *ofdev)
{
printk("mydevice_remove\n");
return 0;
}
static const struct of_device_id mydevice_match[] = {
{
.compatible = "myvendor,mydevice",
},
{}
};
static struct of_platform_driver mydevice_driver = {
.name = "mydevice-driver",
.match_table = mydevice_match,
.probe = mydevice_probe,
.remove = mydevice_remove,
};
static int __init mydevice_driver_init(void)
{
printk("mydevice_drver_init\n");
if (of_register_platform_driver(&mydevice_driver))
printk(KERN_ERR "Unable to register platform driver\n");
return 0;
}
module_init(mydevice_driver_init);
static void __exit mydevice_driver_cleanup(void)
{
printk("mydevice_driver_cleanup\n");
of_unregister_platform_driver(&mydevice_driver);
}
module_exit(mydevice_driver_cleanup);
MODULE_DESCRIPTION("mydevice driver");
MODULE_AUTHOR("name <email>");
MODULE_LICENSE("GPL v2");
MODULE_ALIAS("platform:mydevice-driver");
(3) Change the appropriate Makefile and Kconfig to compile the OF
driver.
During kernel boot you should see the lines:
mydevice_driver_init
mydevice_probe
If not, you probably have one of the strings (text in " ") incorrect.
In /sys/bus/of_platform/drivers, you should have a directory named
'mydevice-driver'.
In /sys/bus/of_platform/drivers/mydevice-driver you should have a
directory named 'mydevice0.1'. The name 'mydevice0' comes from the
.dts above.
==========
Brief explaination of how I think this is all tied together:
(1) The Flattened Device Tree is included with the compiled kernel
image.
(2) The module_init(...) macro is like declaring a 'main' for drivers.
The kernel calls all of the functions declared in the module_init(...)
macros during startup.
(3) When a device driver is registered via
of_register_platform_driver(), this invokes a scan of the FDT to find
matches with strings in the .match_table. If a match is found, the
.probe is called for the created device instance.
Chris
_______________________________________________
Linuxppc-dev mailing list
Linuxppc-dev@lists.ozlabs.org
https://lists.ozlabs.org/listinfo/linuxppc-dev
