* Moving target
@ 2012-08-30 14:14 Guillaume Dargaud
2012-08-30 23:30 ` Michael Ellerman
0 siblings, 1 reply; 4+ messages in thread
From: Guillaume Dargaud @ 2012-08-30 14:14 UTC (permalink / raw)
To: linuxppc-dev
Hello all,
I had a homebrew driver that compiled and ran well on 2.6.38 and I
recently upgraded to the latest xilinx kernel and had some trouble
recompiling without adjustments (of_driver/driver,
of_platform_driver/platform_driver and some such).
But now, after those adjustments, it crashes on run.
My first generic question is: is there a clean canonical example of how
to write each part (module init/exit, /dev handling, probing, physical
memory access, interrupt handling, etc) of a basic driver ? Because each
upgrade breaks my code and as driver writing is only one of my duties, I
have a hard time keeping up with the moving target of the
requirements... To say that books are obsolete is an understatement.
And now to the specifics:
[ 16.655868] {xad_init 519} Module xad: loading...
[ 16.661122] {xad_init 528} Module xad: Major=241, Minor=0, Count=1
[ 16.666231] Unable to handle kernel paging request for data at
address 0x00000030
[ 16.673599] Faulting instruction address: 0xc0116fc0
[ 16.678495] Oops: Kernel access of bad area, sig: 11 [#1]
[ 16.683745] Xilinx Virtex
[ 16.686337] Modules linked in: xad(+)
[ 16.689978] NIP: c0116fc0 LR: c939a0f8 CTR: c0116fa8
[ 16.694912] REGS: c789fd90 TRAP: 0300 Not tainted (3.0.0-14.1-build3+)
[ 16.701629] MSR: 00029030 <EE,ME,CE,IR,DR> CR: 42000022 XER: 20000000
[ 16.708199] DEAR: 00000030, ESR: 00000000
[ 16.712185] TASK = c7851420[281] 'insmod' THREAD: c789e000
[ 16.717441] GPR00: c939a0f8 c789fe40 c7851420 c9397b70 000046d7
ffffffff c0110314 00000000
[ 16.725736] GPR08: c0337380 00000000 00004000 c0116fa8 22000024
100b99d4 ffffffff ffffffff
[ 16.734030] GPR16: ffffffff ffffffff 100b5aed bfa54388 100844d8
100844b8 000007a0 00000000
[ 16.742324] GPR24: c0047edc 00000124 0000001c c9390000 c93973da
c9397b08 c93971e8 c9397b70
[ 16.750870] NIP [c0116fc0] driver_register+0x18/0x144
[ 16.755901] LR [c939a0f8] xad_init+0xf8/0x1e8 [xad]
[ 16.760638] Call Trace:
[ 16.763119] [c789fe40] [c93973da] xad_device_id+0x1da/0xfffffef8
[xad] (unreliable)
[ 16.770719] [c789fe60] [c939a0f8] xad_init+0xf8/0x1e8 [xad]
[ 16.776230] [c789fe80] [c0002508] do_one_initcall+0xe0/0x1c0
[ 16.781871] [c789feb0] [c004a08c] sys_init_module+0x15cc/0x17c0
[ 16.787720] [c789ff40] [c000c95c] ret_from_syscall+0x0/0x3c
[ 16.793212] Instruction dump:
[ 16.796155] 80630034 4bfcd669 80010014 38210010 7c0803a6 4e800020
9421ffe0 7c0802a6
[ 16.803842] bf410008 90010024 7c7f1b78 81230004
[ 16.808257] 7c000034 5400d97e 0f000000
[ 16.813362] ---[ end trace e40dbcf43f9d5d57 ]---
I don't understand the part about address 0x00000030. Does it mean I'm
trying to wrongly access physical/virtual address 0x30 somewhere in my code?
Here are the very basics from my code (I've removed all printk, error
checking and what the driver itself does for clarity). I really need a
hand with the changes of of_something:
static dev_t first;
static unsigned int count = 1;
static int my_major = 241, my_minor = 0;
struct cdev *my_cdev=NULL;
typedef struct XadDevice {
// struct platform_device *of_dev;
struct device *dev;
int irq;
resource_size_t hw_phy_base, hw_length; // Address of the IP resource
void *hw_virt; // Virtual of above
#ifdef DEBUG
void *buffer_virt; // Virtual address of the above
#endif
struct resource *hw_region; // Nothing is done with this
...
} tXadDevice;
tXadDevice Xad;
static irqreturn_t XadIsr(int irq, void *dev_id) { ... }
static int xad_driver_probe(struct device * dev)
struct resource res;
struct device_node *dn = dev->of_node;
int rc=0;
printk(KERN_INFO SD "Probing %s\n" FL, dn->full_name);
rc = of_address_to_resource(dn, 0, &res);
Xad.irq = irq_of_parse_and_map(dn, 0);
rc=request_irq(Xad.irq, XadIsr, IRQF_TRIGGER_RISING /* |
IRQF_DISABLED*/ | IRQF_SHARED | IRQF_SAMPLE_RANDOM, "XadIsr", &Xad);
init_waitqueue_head(&Xad.wait);
Xad.hw_region = request_mem_region((unsigned int)Xad.hw_phy_base,
(unsigned int)(Xad.hw_length), "xps-acqui-data");
Xad.hw_virt= ioremap( (unsigned int)Xad.hw_phy_base, (unsigned
int)(Xad.hw_length) );
dev_set_drvdata(Xad.dev, &Xad);
return 0;
}
///////////////////////////////////////////////////////////////////////////////
// There should be something in:
// ll /sys/devices/plb.0/c9800000.xps-acqui-data
static const struct of_device_id xad_device_id[] = {
{ .compatible = "xlnx,xps-acqui-data-4.00.a" }, // Must match the DTS
{}
};
MODULE_DEVICE_TABLE(of, xad_device_id); // Is this necessary ?
static struct device_driver xad_driver = {
.probe = xad_driver_probe,
.remove = xad_driver_remove,
.name = "xad-driver",
.of_match_table = xad_device_id,
};
...
static struct file_operations fops = {
.owner = THIS_MODULE,
.read = xad_read,
.open = xad_open,
.release = xad_close,
.unlocked_ioctl = xad_ioctl,
};
static int __init xad_init(void) {
first = MKDEV (my_major, my_minor);
register_chrdev_region(first, count, DEVNAME);
my_cdev = cdev_alloc ();
cdev_init(my_cdev, &fops);
rc=cdev_add (my_cdev, first, count);
rc = driver_register(&xad_driver);
printk(KERN_INFO SD "Driver ready!\n" FL);
return 0;
}
module_init(xad_init);
Thanks for reading so far !!!
--
Guillaume Dargaud
http://www.gdargaud.net/
^ permalink raw reply [flat|nested] 4+ messages in thread* Re: Moving target
2012-08-30 14:14 Guillaume Dargaud
@ 2012-08-30 23:30 ` Michael Ellerman
2012-09-10 9:31 ` Guillaume Dargaud
0 siblings, 1 reply; 4+ messages in thread
From: Michael Ellerman @ 2012-08-30 23:30 UTC (permalink / raw)
To: Guillaume Dargaud; +Cc: linuxppc-dev
On Thu, 2012-08-30 at 16:14 +0200, Guillaume Dargaud wrote:
> Hello all,
Hi Guillaume,
> I don't understand the part about address 0x00000030. Does it mean I'm
> trying to wrongly access physical/virtual address 0x30 somewhere in my code?
> [ 16.666231] Unable to handle kernel paging request for data at address 0x00000030
So yes some code is trying to access address 0x30, that is typically a
symptom of dereferencing a NULL pointer.
The 0x30 can be a clue in that it is probably accessing an element of a
structure that is 0x30 past the base of the struct.
> [ 16.673599] Faulting instruction address: 0xc0116fc0
This can be useful if you have the vmlinux around you can look at the
exact instruction that caused the fault.
> [ 16.678495] Oops: Kernel access of bad area, sig: 11 [#1]
> [ 16.683745] Xilinx Virtex
> [ 16.686337] Modules linked in: xad(+)
> [ 16.689978] NIP: c0116fc0 LR: c939a0f8 CTR: c0116fa8
> [ 16.694912] REGS: c789fd90 TRAP: 0300 Not tainted (3.0.0-14.1-build3+)
> [ 16.701629] MSR: 00029030 <EE,ME,CE,IR,DR> CR: 42000022 XER: 20000000
> [ 16.708199] DEAR: 00000030, ESR: 00000000
> [ 16.712185] TASK = c7851420[281] 'insmod' THREAD: c789e000
> [ 16.717441] GPR00: c939a0f8 c789fe40 c7851420 c9397b70 000046d7 ffffffff c0110314 00000000
> [ 16.725736] GPR08: c0337380 00000000 00004000 c0116fa8 22000024 100b99d4 ffffffff ffffffff
> [ 16.734030] GPR16: ffffffff ffffffff 100b5aed bfa54388 100844d8 100844b8 000007a0 00000000
> [ 16.742324] GPR24: c0047edc 00000124 0000001c c9390000 c93973da c9397b08 c93971e8 c9397b70
> [ 16.750870] NIP [c0116fc0] driver_register+0x18/0x144
That is the exact instruction that faulted. You can see it's not
actually in your code, it's in driver_register().
> ///////////////////////////////////////////////////////////////////////////////
> // There should be something in:
> // ll /sys/devices/plb.0/c9800000.xps-acqui-data
> static const struct of_device_id xad_device_id[] = {
> { .compatible = "xlnx,xps-acqui-data-4.00.a" }, // Must match the DTS
> {}
> };
>
> MODULE_DEVICE_TABLE(of, xad_device_id); // Is this necessary ?
>
> static struct device_driver xad_driver = {
> .probe = xad_driver_probe,
> .remove = xad_driver_remove,
> .name = "xad-driver",
> .of_match_table = xad_device_id,
> };
> static int __init xad_init(void) {
> first = MKDEV (my_major, my_minor);
> register_chrdev_region(first, count, DEVNAME);
> my_cdev = cdev_alloc ();
>
> cdev_init(my_cdev, &fops);
> rc=cdev_add (my_cdev, first, count);
>
> rc = driver_register(&xad_driver);
>
> printk(KERN_INFO SD "Driver ready!\n" FL);
> return 0;
> }
I don't think you should be using driver_register().
I think instead you want this to be a platform_driver, and use
platform_driver_register() ?
If you grep for platform_driver_register() in arch/powerpc you will see
several examples.
cheers
^ permalink raw reply [flat|nested] 4+ messages in thread
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2012-08-30 15:25 ` Moving target Andreas Schwab
2012-08-30 14:14 Guillaume Dargaud
2012-08-30 23:30 ` Michael Ellerman
2012-09-10 9:31 ` Guillaume Dargaud
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