I can't get classID of PCI device.

Shvets04 · **Joined:** Wed Feb 13, 2019 3:07 pm **Posts:** 28

hi, i write pci driver. but my function get_class_id returns 0x0 for all detected device.

Code:

u16 get_class_id(u16 bus, u16 device, u16 function)
{
        u32 r0 = pci_read_word(bus,device,function,0xa);
        return (r0 & ~0x00FF) >> 8;
}

full code - https://github.com/s04v/OSv1.0/blob/mas ... vers/pci.c

how to solve this problem?

nullplan · **Joined:** Wed Aug 30, 2017 8:24 am **Posts:** 1604

That is a misaligned read. The offset always needs to be divisible by 4, meaning in hex it always has to end in 0, 4, 8, or C. In your case:

Code:

u16 get_class_id(u16 bus, u16 device, u16 function)
{
        u32 r0 = pci_read_word(bus,device,function,0x8);
        return (r0 >> 24) & 0xFF;
}

Octocontrabass · **Joined:** Mon Mar 25, 2013 7:01 pm **Posts:** 5137

You shouldn't copy someone else's code if you don't understand it.

I suspect this mistake originates in the wiki, where the example function reads 16-bit words despite configuration mechanism 1 functioning exclusively in 32-bit dwords.

Shvets04 · **Joined:** Wed Feb 13, 2019 3:07 pm **Posts:** 28

nullplan wrote:

That is a misaligned read. The offset always needs to be divisible by 4, meaning in hex it always has to end in 0, 4, 8, or C. In your case:

Code:

u16 get_class_id(u16 bus, u16 device, u16 function)
{
        u32 r0 = pci_read_word(bus,device,function,0x8);
        return (r0 >> 24) & 0xFF;
}

It's not working correctly

Shvets04 · **Joined:** Wed Feb 13, 2019 3:07 pm **Posts:** 28

Octocontrabass wrote:

You shouldn't copy someone else's code if you don't understand it.

I suspect this mistake originates in the wiki, where the example function reads 16-bit words despite configuration mechanism 1 functioning exclusively in 32-bit dwords.

where can i find correct function definition?
I take it there's a problem with this line?

Code:

tmp = (u16)((inw(0xCFC) >> ((offset & 2) * 8)) & 0xffff);

rkennedy9064 · **Joined:** Wed Sep 01, 2010 3:54 pm **Posts:** 36

Shvets04 wrote:

Octocontrabass wrote:

You shouldn't copy someone else's code if you don't understand it.

I suspect this mistake originates in the wiki, where the example function reads 16-bit words despite configuration mechanism 1 functioning exclusively in 32-bit dwords.

where can i find correct function definition?
I take it there's a problem with this line?

Code:

tmp = (u16)((inw(0xCFC) >> ((offset & 2) * 8)) & 0xffff);

My guess would probably be inw, which is defined as u16 inw(u16 port) in your port.h. Those ports read and write 32 bits, so you read the full int and then break it up. This is how I do it in my OS, but my code isn't C/C++.

Code:

let (device_id, vendor_id) = read_2_words(address, 0x00);

fn read_2_words(address: u32, offset: u32) -> (u16, u16) {
    let value = read_offset(address, offset);
    let high_word = (value >> 16) as u16;
    let low_word = value as u16;
    (high_word, low_word)
}

fn read_offset(mut address: u32, offset: u32) -> u32 {
    let mut config_address = Port::new(CONFIG_ADDRESS);
    let mut data_address = Port::new(DATA_ADDRESS);
    address |= offset & 0xFC;
    unsafe {
        config_address.write(address);
        data_address.read()
    }
}

Klakap · **Joined:** Sat Mar 10, 2018 10:16 am **Posts:** 296

Code:

u16 pci_read_word(u8 bus, u8 slot, u8 func, u8 offset)
{
   u32 address;
    u32 lbus = (u32)bus;
    u32 lslot = (u32)slot;
    u32 lfunc = (u32)func;
    u16 tmp = 0;
    address = (u32)((lbus << 16) | (lslot << 11) |
              (lfunc << 8) | (offset & 0xfc) | ((u32)0x80000000));
    outw(0xCF8, address);
    tmp = (u16)((inw(0xCFC) >> ((offset & 2) * 8)) & 0xffff);
    return (tmp);
}

You must use outl and inl functions.

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I can't get classID of PCI device.

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