读pci寄存器的疑问。。。

chishanmingshen

1. 
   
2. 
   
3. /*
   
4. * Functions for accessing PCI base (first 256 bytes) and extended
   
5. * (4096 bytes per PCI function) configuration space with type 1
   
6. * accesses.
   
7. */
   
8. 
   
9. #define PCI_CONF1_ADDRESS(bus, devfn, reg) \
   
10.     (0x80000000 | ((reg & 0xF00) << 16) | (bus << 16) \
    
11.     | (devfn << 8) | (reg & 0xFC))
    
12. 
    
13. static int pci_conf1_read(unsigned int seg, unsigned int bus,
    
14.               unsigned int devfn, int reg, int len, u32 *value)
    
15. {
    
16.     unsigned long flags;
    
17. 
    
18.     if (seg || (bus > 255) || (devfn > 255) || (reg > 4095)) {《------为何跟4096做比较？不是256？
    
19.         *value = -1;
    
20.         return -EINVAL;
    
21.     }
    
22. 
    
23.     raw_spin_lock_irqsave(&pci_config_lock, flags);
    
24. 
    
25.     outl(PCI_CONF1_ADDRESS(bus, devfn, reg), 0xCF8);
    
26. 
    
27.     switch (len) {
    
28.     case 1:
    
29.         *value = inb(0xCFC + (reg & 3));
    
30.         break;
    
31.     case 2:
    
32.         *value = inw(0xCFC + (reg & 2));
    
33.         break;
    
34.     case 4:
    
35.         *value = inl(0xCFC);
    
36.         break;
    
37.     }
    
38. 
    
39.     raw_spin_unlock_irqrestore(&pci_config_lock, flags);
    
40. 
    
41.     return 0;
    
42. }

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CONFIG_PCI_DIRECT打开时怎么也能支持4k？请指点啊，谢谢！

humjb_1983

看似pcie 的4k配置空间

chishanmingshen

回复 2# humjb_1983

跟pcie没有任何关系！
我查到了，是为了AMD的一款的特殊的处理。

1. commit 831d991821daedd4839073dbca55514432ef1768
   
2. Author: Robert Richter <robert.richter@amd.com>
   
3. Date:   Mon Sep 3 10:17:39 2007 +0200
   
4. 
   
5.     x86: add PCI extended config space access for AMD Barcelona
   
6.    
   
7.     This patch implements PCI extended configuration space access for
   
8.     AMD's Barcelona CPUs. It extends the method using CF8/CFC IO
   
9.     addresses. An x86 capability bit has been introduced that is set for
   
10.     CPUs supporting PCI extended config space accesses.

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humjb_1983

呵呵，学习了~

kiongf

  我之前也一直以为这个是为了pcie的4096字节配置空间，原来还是这样子.学习了