Re: PCI driver

Manu Abraham
2005-09-15T07:57:03Z

Rolf Eike Beer wrote:

>Manu Abraham wrote:
>
>
>>Jiri Slaby wrote:
>>
>>
>>>Manu Abraham napsal(a):
>>>
>>>
>>>>Jiri Slaby wrote:
>>>>
>>>>
>>>>>Manu Abraham napsal(a):
>>>>>
>>>>>
>>>>>>Jiri Slaby wrote:
>>>>>>
>>>>>>
>>>>>>>you do NOT do this at all, because you have pdev already (the param
>>>>>>>of the probe function)
>>>>>>>
>>>>>>>
>>>>>>I rewrote the entire thing like this including the pci_remove
>>>>>>function too, but now it so seems that in the remove function,
>>>>>>pci_get_drvdata(pdev) returns NULL, and hence i get an Oops at
>>>>>>module removal.
>>>>>>
>>>>>>
>>>>I just found that, pci_enable_device() fails. So what's the way to go
>>>>ahead ?
>>>>
>>>>
>>>JESUS.
>>>
>>>
>>Hmm.. i finally got it to work. It seems pci_get_device() is necessary,
>>i can't seem to enable the device or request for an IRQ the way you
>>suggested. It looks some quirks are there though ..
>>
>>If only i could explain why it works this way and not the other way ..
>>
>>
>
>Because pci_enable_device() works like most other kernel (and also libc)
>functions: it returns 0 if everything went fine.
>
>
>
>
>>[ 81.269655] mantis_pci_probe: Got a device
>>[ 81.269825] mantis_pci_probe: We got an IRQ
>>[ 81.269987] mantis_pci_probe: We finally enabled the device
>>[ 81.270191] Mantis Rev 1, irq: 23, latency: 32
>>[ 81.270289] memory: 0xefeff000, mmio: f9218000
>>[ 81.270519] Trying to free free IRQ23
>>[ 90.485885] mantis_pci_remove: Removing -->Mantis irq: 23, latency: 32
>>[ 90.485887] memory: 0xefeff000, mmio: 0xf9218000
>>[ 90.486293] Trying to free free IRQ23
>>[ 90.486429] Trying to free nonexistent resource <efeff000-efefffff>
>>
>>
>
>You should introduce a table of PCI devices here that your driver feels
>responsible for. Then put this into a struct pci_driver which you pass to
>
>
I am in fact doing that ..

static *struct* pci_device_id mantis_pci_table[] = {
{ PCI_DEVICE(PCI_VENDOR_ID_MANTIS, PCI_DEVICE_ID_MANTIS_R11) },
{ 0 },
};

MODULE_DEVICE_TABLE(pci, mantis_pci_table);

static *struct* pci_driver mantis_pci_driver = {
.name = "Mantis PCI combo driver",
.id_table = mantis_pci_table,
.probe = mantis_pci_probe,
.remove = mantis_pci_remove,
};

static int __devinit mantis_pci_init(void)
{
*return* pci_register_driver(&mantis_pci_driver);
}

static void __devexit mantis_pci_exit(void)
{
pci_unregister_driver(&mantis_pci_driver);
}

module_init(mantis_pci_init);
module_exit(mantis_pci_exit);

MODULE_DESCRIPTION("Mantis PCI DTV bridge driver");
MODULE_AUTHOR("Manu Abraham");
MODULE_LICENSE("GPL");

>pci_module_init. Take a look on a random other PCI driver,
>drivers/net/8139too.c, drivers/scsi/aic7xxx/aic7xxx_osm_pci.c, whatever.
>
>
>
>>static int __devinit mantis_pci_probe(struct pci_dev *pdev, const struct
>>pci_device_id *mantis_pci_table)
>>{
>> u8 revision, latency;
>> u8 data[2];
>> struct mantis_pci *mantis;
>> mantis = (struct mantis_pci *) kmalloc(sizeof (struct mantis_pci),
>>GFP_KERNEL);
>> if (mantis == NULL) {
>> dprintk(verbose, MANTIS_ERROR, 1, "Out of memory");
>> return -ENOMEM;
>> }
>>
>> pdev = pci_get_device(PCI_VENDOR_ID_MANTIS, PCI_DEVICE_ID_MANTIS_R11,
>>NULL);
>>
>>
>
>This is not needed anymore then. Your probe function will get called with for
>any pci dev your driver can handle.
>
>
>

I will just check it up again to see what went wrong ..

>> if (pdev) {
>> dprintk(verbose, MANTIS_ERROR, 1, "Got a device");
>> mantis->mantis_addr = pci_resource_start(pdev, 0);
>> if (!request_mem_region(pci_resource_start(pdev, 0),
>> pci_resource_len(pdev, 0), DRIVER_NAME)) {
>> dprintk(verbose, MANTIS_ERROR, 1, "Request for memory region failed");
>>
>>
>
>Line length is maximum 80 characters. See Documentation/CodingStyle
>
>

That was not meant to go into the kernel straight away, as it needs
*lot* of work, the PCI part is only something extremely small.

>
>
>> goto err0;
>> }
>> if ((mantis->mantis_mmio = ioremap(mantis->mantis_addr, 0x1000)) == NULL) {
>> dprintk(verbose, MANTIS_ERROR, 1, "IO remap failed");
>> goto err1;
>> }
>> if (request_irq(pdev->irq, (void *) mantis_pci_irq, SA_SHIRQ |
>> SA_INTERRUPT, DRIVER_NAME, (void *) mantis) < 0) {
>>
>>
>
>You don't need to cast a pointer to void* or vice versa.
>
>
>
Ah, thanks ...

>> dprintk(verbose, MANTIS_ERROR, 1, "Mantis IRQ registration failed");
>> goto err2;
>> }
>> dprintk(verbose, MANTIS_DEBUG, 1, "We got an IRQ");
>> if (pci_enable_device(pdev)) {
>> dprintk(verbose, MANTIS_ERROR, 1, "Mantis PCI device enable failed");
>> goto err3;
>> }
>> dprintk(verbose, MANTIS_DEBUG, 1, "We finally enabled the device");
>> pci_set_master(pdev);
>> pci_read_config_byte(pdev, PCI_LATENCY_TIMER, &latency);
>> pci_read_config_byte(pdev, PCI_CLASS_REVISION, &revision);
>> mantis->latency = latency;
>> mantis->revision = revision;
>> if (!latency) {
>> pci_write_config_byte(pdev, PCI_LATENCY_TIMER, 32);
>> }
>>
>>
>
>The value in mantis->latency and the one in the card's address space now differ.
>
>

Yes, i set it to the default latency as specified by vendor.. But
temporarily to test the card ..

>
>
>> pci_set_drvdata(pdev, mantis);
>> dprintk(verbose, MANTIS_ERROR, 0, "Mantis Rev %d, ", mantis->revision);
>> dprintk(verbose, MANTIS_ERROR, 0, "irq: %d, latency: %d\nmemory:
>>0x%04x, mmio: %p\n", pdev->irq, mantis->latency,
>> mantis->mantis_addr, mantis->mantis_mmio);
>>
>> pci_dev_put(pdev);
>>
>>
>
>No, DON'T DO THAT! This will drop the a reference count from the struct
>pci_dev, which means it can get freed while your driver still wants to work
>with it.
>
>
>

Hmm.. I thought after i make a call to pci_get_device(), i have to do a
pci_dev_put() after the usage ..
I was a bit lost when to use pci_dev_put() in this case.

>> } else {
>> dprintk(verbose, MANTIS_ERROR, 1, "No device found");
>> return -ENODEV;
>> }
>>
>>err3:
>> free_irq(pdev->irq, pdev);
>>err2:
>> if (mantis->mantis_mmio)
>> iounmap(mantis->mantis_mmio);
>>err1:
>> release_mem_region(pci_resource_start(pdev, 0),
>> pci_resource_len(pdev, 0));
>>err0:
>> kfree(mantis);
>>
>> return 0;
>>}
>>
>>
>>static void __devexit mantis_pci_remove(struct pci_dev *pdev)
>>{
>> struct mantis_pci *mantis = pci_get_drvdata(pdev);
>> if (mantis == NULL) {
>> dprintk(verbose, MANTIS_ERROR, 1, "Aeio, MAntis NULL ptr");
>>
>>
>
>a) this should really never happen. If it happens, it's a kernel bug.
>b) if you catch this error while debugging, you should return here so you do
> not dereference this NULL pointer.
>
>
>
Ack.

>> }
>> dprintk(verbose, MANTIS_ERROR, 1, "Removing -->Mantis irq: %d, latency:
>>%d\nmemory: 0x%04x, mmio: 0x%p", pdev->irq, mantis->latency,
>> mantis->mantis_addr, mantis->mantis_mmio);
>>
>> free_irq(pdev->irq, pdev);
>>
>> release_mem_region(pci_resource_start(pdev, 0),
>> pci_resource_len(pdev, 0));
>> pci_disable_device(pdev);
>> pci_set_drvdata(pdev, NULL);
>> kfree(mantis);
>>}
>>
>>

Thanks ..

Regards,
Manu