Linux下C如何調用PCI Lib函數
在Linux下,可以通過"setpci"和"setpci"指令來通路PCI裝置的配置空間,那麼能否用程式來通路PCI 配置空間呢?答案當然是肯定的,linux下提供了多個pci庫以供應用程式通路。下面就以最常見的為例,從安裝、使用和編譯的角度分别進行說明。
安裝
在centos中,用超級使用者權限,可用下面的指令檢視到和pci通路相關的庫包括:
libpciaccess.i686 : PCI access library
libpciaccess.x86_64 : PCI access library
libpciaccess-devel.i686 : PCI access library development package
libpciaccess-devel.x86_64 : PCI access library development package
pciutils.x86_64 : PCI bus related utilities
pciutils-devel.i686 : Linux PCI development library
pciutils-devel.x86_64 : Linux PCI development library
pciutils-devel-static.i686 : Linux PCI static library
pciutils-devel-static.x86_64 : Linux PCI static library
pciutils-libs.i686 : Linux PCI library
pciutils-libs.x86_64 : Linux PCI library
由于實際系統是64bit的,并且以靜态庫的形式進行使用,可以用下面的指令安裝pci lib 庫:
yum install libpciaccess.x86_64 libpciaccess-devel.x86_64 pciutils-devel-static.x86_64
安裝完後,可以看到相應的頭檔案已經最/usr/include下面了:
[root@localhost include]# find ./ -name "*pci*"
./linux/pci.h
./linux/pci_regs.h
./linux/virtio_pci.h
./sys/pci.h
./pci
./pci/pci.h
./pciaccess.h
并且靜态庫也已經存在了:
[root@localhost lib64]# find ./ -name "*pci*"
./kde4/kcm_pci.so
./pkgconfig/libpci.pc
./pkgconfig/pciaccess.pc
./libpci.so.3
./libpci.so.3.2.1
./libpciaccess.so.0
./libpciaccess.so.0.11.1
./libpci.so
./libpci.a
./libpciaccess.so
通過上面的輸出可以看到,libpciaccess隻有動态庫的形式,而libpci既有動态庫也有靜态庫,這個和我們輸入的" yum install libpciaccess.x86_64 libpciaccess-devel.x86_64 pciutils-devel-static.x86_64"指令是吻合的。
使用
打開/usr/include/pci/pci.h,可以找到我們需要的函數:
u8 pci_read_byte(struct pci_dev *, int pos) PCI_ABI; /* Access to configuration space */
u16 pci_read_word(struct pci_dev *, int pos) PCI_ABI;
u32 pci_read_long(struct pci_dev *, int pos) PCI_ABI;
int pci_read_block(struct pci_dev *, int pos, u8 *buf, int len) PCI_ABI;
int pci_read_vpd(struct pci_dev *d, int pos, u8 *buf, int len) PCI_ABI;
int pci_write_byte(struct pci_dev *, int pos, u8 data) PCI_ABI;
int pci_write_word(struct pci_dev *, int pos, u16 data) PCI_ABI;
int pci_write_long(struct pci_dev *, int pos, u32 data) PCI_ABI;
int pci_write_block(struct pci_dev *, int pos, u8 *buf, int len) PCI_ABI;
打開/usr/include/pciaccess.h,也有可以通路配置空間的函數:
struct pci_io_handle *pci_device_open_io(struct pci_device *dev, pciaddr_t base,
pciaddr_t size);
struct pci_io_handle *pci_legacy_open_io(struct pci_device *dev, pciaddr_t base,
void pci_device_close_io(struct pci_device *dev, struct pci_io_handle *handle);
uint32_t pci_io_read32(struct pci_io_handle *handle, uint32_t reg);
uint16_t pci_io_read16(struct pci_io_handle *handle, uint32_t reg);
uint8_t pci_io_read8(struct pci_io_handle *handle, uint32_t reg);
void pci_io_write32(struct pci_io_handle *handle, uint32_t reg, uint32_t data);
void pci_io_write16(struct pci_io_handle *handle, uint32_t reg, uint16_t data);
void pci_io_write8(struct pci_io_handle *handle, uint32_t reg, uint8_t data);
從上面的兩組函數接口來看,可以看到pciutils需要初始化struct pci_dev,而pciasscess庫需要初始化struct pci_io_handle *handle。那麼該如何使用pciutils靜态庫呢,通過繼續閱讀/usr/include/pci/pci.h,可以看到下面的函數聲明和注釋:
/* Initialize PCI access */
struct pci_access *pci_alloc(void) PCI_ABI;
void pci_init(struct pci_access *) PCI_ABI;
void pci_cleanup(struct pci_access *) PCI_ABI;
/* Scanning of devices */
void pci_scan_bus(struct pci_access *acc) PCI_ABI;
struct pci_dev *pci_get_dev(struct pci_access *acc, int domain, int bus, int dev, int func) PCI_ABI; /* Raw access to specified device */
void pci_free_dev(struct pci_dev *) PCI_ABI;
據此我們不難猜測出使用pciutils的代碼流程,并且根據頭檔案說明實作一個測試代碼test_pcilib.c:
int main(void)
{
int i = 0;
int ret = 0;
struct pci_access * myaccess;
struct pci_dev * mydev;
myaccess = pci_alloc();
pci_init(myaccess);
mydev = pci_get_dev(myaccess, 0, 6, 0, 0);
for (i = 0; i < 256; i++) {
ret = pci_read_byte(mydev, i);
printf("%d: %02x\n", i, ret);
}
pci_free_dev(mydev);
pci_cleanup(myaccess);
return 0;
}
編譯
因為已經知道上面的代碼依賴于libpci.a靜态庫,為此可用用下面的gcc指令進行簡單編譯:
[root@localhost testcases]# gcc -c -o test_pci.o test_pcilib.c
[root@localhost testcases]# gcc -Wall -o test_pci test_pci.o /usr/lib64/libpci.a
[root@localhost testcases]# ./test_pci
0: b5
1: 10
2: a0
3: 87
4: 07
5: 04
6: 10
7: 00
8: ca
9: 00
10: 80
11: 06
12: 10
.....
本文轉自存儲之廚51CTO部落格,原文連結:http://blog.51cto.com/xiamachao/1744433 ,如需轉載請自行聯系原作者