PCI 驱动编程基础
Posted Li-Yongjun
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lspci
lspci 可以列出系统中所有的 PCI 设备。
$ lspci
00:00.0 Host bridge: Intel Corporation 440FX - 82441FX PMC [Natoma] (rev 02)
00:01.0 ISA bridge: Intel Corporation 82371SB PIIX3 ISA [Natoma/Triton II]
00:01.1 IDE interface: Intel Corporation 82371AB/EB/MB PIIX4 IDE (rev 01)
00:02.0 VGA compatible controller: VMware SVGA II Adapter
00:03.0 Ethernet controller: Intel Corporation 82540EM Gigabit Ethernet Controller (rev 02)
00:04.0 System peripheral: InnoTek Systemberatung GmbH VirtualBox Guest Service
00:05.0 Multimedia audio controller: Intel Corporation 82801AA AC’97 Audio Controller (rev 01)
00:07.0 Bridge: Intel Corporation 82371AB/EB/MB PIIX4 ACPI (rev 08)
00:0c.0 USB controller: Intel Corporation 7 Series/C210 Series Chipset Family USB xHCI Host Controller
00:0d.0 SATA controller: Intel Corporation 82801HM/HEM (ICH8M/ICH8M-E) SATA Controller [AHCI mode] (rev 02)
以加粗那行 PCI 设备为例
00 是 Bus ID
03 是 Device ID
0 是 Function ID
lspci -v 显示设备详细的信息
$ lspci -v
00:03.0 Ethernet controller: Intel Corporation 82540EM Gigabit Ethernet Controller (rev 02)
Subsystem: Intel Corporation PRO/1000 MT Desktop Adapter
Flags: 66MHz, medium devsel, IRQ 19
Memory at f0200000 (32-bit, non-prefetchable) [size=128K]
I/O ports at d020 [size=8]
Capabilities:
Kernel driver in use: e1000
Kernel modules: e1000
还是以上面的 PCI 设备为例:
- Flags: 66MHz, medium devsel, IRQ 19：中断号为 19
- Memory at f0200000：地址为 f0200000
- Kernel driver in use: e1000 ：表示该设备使用的驱动为 e1000
lspci -x 以十六进制显示 PCI 配置空间 (configuration space) 的前64个字节映象 (标准头部信息)
$ lspci -x
00:03.0 Ethernet controller: Intel Corporation 82540EM Gigabit Ethernet Controller (rev 02)
00: 86 80 0e 10 03 00 30 02 02 00 00 02 00 40 00 00
10: 00 00 20 f0 00 00 00 00 21 d0 00 00 00 00 00 00
20: 00 00 00 00 00 00 00 00 00 00 00 00 86 80 1e 00
30: 00 00 00 00 dc 00 00 00 00 00 00 00 09 01 ff 00
配置空间
标准头信息占 64 字节，内容如下
对照 lspci -x 显示的信息，整理如下
配置寄存器地址空间，64 字节头
#define PCI_STD_HEADER_SIZEOF 64
#define PCI_VENDOR_ID 0x00 /* 16 bits */
#define PCI_DEVICE_ID 0x02 /* 16 bits */
#define PCI_COMMAND 0x04 /* 16 bits */
#define PCI_STATUS 0x06 /* 16 bits */
#define PCI_CLASS_REVISION 0x08 /* High 24 bits are class, low 8 revision */
#define PCI_REVISION_ID 0x08 /* Revision ID */
#define PCI_CLASS_PROG 0x09 /* Reg. Level Programming Interface */
#define PCI_CACHE_LINE_SIZE 0x0c /* 8 bits */
#define PCI_LATENCY_TIMER 0x0d /* 8 bits */
#define PCI_HEADER_TYPE 0x0e /* 8 bits */
#define PCI_BIST 0x0f /* 8 bits */
#define PCI_BASE_ADDRESS_0 0x10 /* 32 bits */
#define PCI_BASE_ADDRESS_1 0x14 /* 32 bits [htype 0,1 only] */
#define PCI_BASE_ADDRESS_2 0x18 /* 32 bits [htype 0 only] */
#define PCI_BASE_ADDRESS_3 0x1c /* 32 bits */
#define PCI_BASE_ADDRESS_4 0x20 /* 32 bits */
#define PCI_BASE_ADDRESS_5 0x24 /* 32 bits */
#define PCI_CARDBUS_CIS 0x28
#define PCI_SUBSYSTEM_VENDOR_ID 0x2c
#define PCI_SUBSYSTEM_ID 0x2e
#define PCI_ROM_ADDRESS 0x30 /* Bits 31..11 are address, 10..1 reserved */
#define PCI_CAPABILITY_LIST 0x34 /* Offset of first capability list entry */
#define PCI_INTERRUPT_LINE 0x3c /* 8 bits */
#define PCI_INTERRUPT_PIN 0x3d /* 8 bits */
#define PCI_MIN_GNT 0x3e /* 8 bits */
#define PCI_MAX_LAT 0x3f /* 8 bits */
PCI 驱动 demo
环境：Ubuntu 20.04 虚拟机，有个 Intel 网卡，也就是上面例子中的 00:03.0 设备，默认使用的驱动是 e1000，我们写个 demo，"驱动"这个设备，所以先将原驱动卸载
$ sudo rmmod e1000
my_pci.c
#include <linux/module.h>
#include <linux/pci.h>
#define DRV_NAME "my_pci_driver"
struct pci_card
// 端口读写变量
resource_size_t io_start;
resource_size_t io_end;
long range;
long flags;
void __iomem *ioaddr;
int irq;
;
void my_pci_get_configs(struct pci_dev *dev)
uint8_t val1;
uint16_t val2;
uint32_t val4;
pci_read_config_word(dev, PCI_VENDOR_ID, &val2);
printk("vendor id = 0x%x\\n", val2);
pci_read_config_word(dev, PCI_DEVICE_ID, &val2);
printk("device id = 0x%x\\n", val2);
pci_read_config_byte(dev, PCI_REVISION_ID, &val1);
printk("revision id = 0x%x\\n", val1);
pci_read_config_dword(dev, PCI_CLASS_REVISION, &val4);
printk("class = 0x%x\\n", val4 >> 8);
pci_read_config_byte(dev, PCI_CACHE_LINE_SIZE, &val1);
printk("cache line size = 0x%x\\n", val1);
pci_read_config_byte(dev, PCI_LATENCY_TIMER, &val1);
printk("latency time = 0x%x\\n", val1);
pci_read_config_byte(dev, PCI_HEADER_TYPE, &val1);
printk("header type = 0x%x\\n", val1);
pci_read_config_byte(dev, PCI_BIST, &val1);
printk("bist = 0x%x\\n", val1);
pci_read_config_dword(dev, PCI_BASE_ADDRESS_0, &val4);
printk("base address 0 = 0x%x\\n", val4);
pci_read_config_dword(dev, PCI_BASE_ADDRESS_1, &val4);
printk("base address 1 = 0x%x\\n", val4);
pci_read_config_dword(dev, PCI_BASE_ADDRESS_2, &val4);
printk("base address 2 = 0x%x\\n", val4);
pci_read_config_dword(dev, PCI_BASE_ADDRESS_3, &val4);
printk("base address 3 = 0x%x\\n", val4);
pci_read_config_dword(dev, PCI_BASE_ADDRESS_4, &val4);
printk("base address 4 = 0x%x\\n", val4);
pci_read_config_dword(dev, PCI_BASE_ADDRESS_5, &val4);
printk("base address 5 = 0x%x\\n", val4);
pci_read_config_dword(dev, PCI_CARDBUS_CIS, &val4);
printk("card bus cis = 0x%x\\n", val4);
pci_read_config_word(dev, PCI_SUBSYSTEM_VENDOR_ID, &val2);
printk("subsystem vendor id = 0x%x\\n", val2);
pci_read_config_word(dev, PCI_SUBSYSTEM_ID, &val2);
printk("subsystem id = 0x%x\\n", val2);
pci_read_config_byte(dev, PCI_CAPABILITY_LIST, &val1);
printk("capability list = 0x%x\\n", val1);
pci_read_config_byte(dev, PCI_INTERRUPT_LINE, &val1);
printk("interrupt line = 0x%x\\n", val1);
pci_read_config_byte(dev, PCI_INTERRUPT_PIN, &val1);
printk("interrupt pin = 0x%x\\n", val1);
pci_read_config_byte(dev, PCI_MIN_GNT, &val1);
printk("min gnt = 0x%x\\n", val1);
pci_read_config_byte(dev, PCI_MAX_LAT, &val1);
printk("max lat = 0x%x\\n", val1);
static irqreturn_t my_pci_interrupt(int irq, void *dev_id)
struct pci_card *mypci = (struct pci_card *)dev_id;
printk("irq = %d, mypci_irq = %d\\n", irq, mypci->irq);
return IRQ_HANDLED;
static int probe(struct pci_dev *pci_dev, const struct pci_device_id *ent)
int rc;
struct pci_card *my_pci = NULL;
printk("%s() line:%d\\n", __FUNCTION__, __LINE__);
rc = pci_enable_device(pci_dev);
if (rc)
printk("pci enable device failed!\\n");
goto out_mypci;
my_pci = kmalloc(sizeof(struct pci_card),
GFP_KERNEL); // GFP_KERNEL 是内核内存分配时最常用的，无内存可用时可引起休眠。
if (my_pci == NULL)
printk("kmalloc error!\\n");
rc = -ENOMEM;
goto out_mypci;
my_pci->irq = pci_dev->irq;
if (my_pci->irq < 0)
printk("IRQ is %d, it is invalid\\n", my_pci->irq);
goto out_mypci;
my_pci->io_start = pci_resource_start(pci_dev, 0); // bar0
my_pci->io_end = pci_resource_end(pci_dev, 0);
my_pci->range = my_pci->io_end - my_pci->io_start + 1;
my_pci->flags = pci_resource_flags(pci_dev, 0);
printk("io_start = 0x%llx\\n", my_pci->io_start);
printk("io_end = 0x%llx\\n", my_pci->io_end);
printk("range = 0x%lx\\n", my_pci->range);
printk("flags = 0x%lx\\n", my_pci->flags);
printk("PCI base addr 0 is io%s.\\n", (my_pci->flags & IORESOURCE_MEM) ? "mem" : "port");
rc = pci_request_regions(pci_dev, DRV_NAME);
if (rc)
printk("pci request regions error!\\n");
goto out_mypci;
my_pci->ioaddr = pci_ioremap_bar(pci_dev, 0);
if (my_pci->ioaddr == NULL)
printk("ioremp error!\\n");
rc = ENOMEM;
goto out_regions;
rc = request_irq(my_pci->irq, my_pci_interrupt, IRQF_SHARED, DRV_NAME, my_pci);
if (rc)
printk(KERN_ERR "can't get assigned IRQ %d!\\n", my_pci->irq);
goto out_iounmap;
pci_set_drvdata(pci_dev, my_pci);
printk("probe success. PCI ioport addr start addr 0x%llx, ioaddr is 0x%p, interrupt No. %d\\n",
my_pci->io_start, my_pci->ioaddr, my_pci->irq);
my_pci_get_configs(pci_dev);
return 0;
out_iounmap:
iounmap(my_pci->ioaddr);
out_regions:
pci_release_regions(pci_dev);
out_mypci:
if (my_pci)
kfree(my_pci);
return rc;
static void remove(struct pci_dev *pci_dev)
struct pci_card *my_pci;
printk("%s() line:%d\\n", __FUNCTION__, __LINE__);
my_pci = pci_get_drvdata(pci_dev);
if (my_pci)
free_irq(my_pci->irq, my_pci);
iounmap(my_pci->ioaddr);
kfree(my_pci);
pci_release_regions(pci_dev);
pci_disable_device(pci_dev);
printk("device is removed successfully\\n");
static const struct pci_device_id my_pci_tbl[] =
PCI_DEVICE(PCI_VENDOR_ID_INTEL, 0x100e),
;
static struct pci_driver mv_pci_driver =
.name = DRV_NAME,
.id_table = my_pci_tbl,
.probe = probe,
.remove = remove,
;
static int my_pci_init(void)
printk("%s() line:%d\\n", __FUNCTION__, __LINE__);
return pci_register_driver(&mv_pci_driver);
static void my_pci_exit(void)
printk("%s() line:%d\\n", __FUNCTION__, __LINE__);
pci_unregister_driver(&mv_pci_driver);
module_init(my_pci_init);
module_exit(my_pci_exit);
MODULE_LICENSE("GPL");
Makefile
obj-m = my_pci.o
all:
make -C /lib/modules/$(shell uname -r)/build/ M=$PWD modules
clean:
make -C /lib/modules/$(shell uname -r)/build/ M=$PWD clean
$ sudo rmmod e1000
$ sudo insmod my_pci.ko
$ dmesh
[48344.049257] my_pci_init() line:204
[48344.049285] probe() line:102
[48344.049746] io_start = 0xf0200000
[48344.049748] io_end = 0xf021ffff
[48344.049749] range = 0x20000
[48344.049749] flags = 0x40200
[48344.049750] PCI base addr 0 is iomem.
[48344.049807] probe success. PCI ioport addr start addr 0xf0200000, ioaddr is 0x000000000e21ae12, interrupt No. 19
[48344.049817] vendor id = 0x8086
[48344.049823] device id = 0x100e
[48344.049830] revision id = 0x2
[48344.049837] class = 0x20000
[48344.049843] cache line size = 0x0
[48344.049850] latency time = 0x40
[48344.049856] header type = 0x0
[48344.049863] bist = 0x0
[48344.049869] base address 0 = 0xf0200000
[48344.049876] base address 1 = 0x0
[48344.049882] base address 2 = 0xd021
[48344.049888] base address 3 = 0x0
[48344.049895] base address 4 = 0x0
[48344.049901] base address 5 = 0x0
[48344.049908] card bus cis = 0x0
[48344.049914] subsystem vendor id = 0x8086
[48344.049921] subsystem id = 0x1e
[48344.049927] capability list = 0xdc
[48344.049933] interrupt line = 0x9
[48344.049940] interrupt pin = 0x1
[48344.049946] min gnt = 0xff
[48344.049953] max lat = 0x0
$ sudo rmmod my_pci
[51661.250413] my_pci_exit() line:211
[51661.250433] remove() line:175
[51661.250939] device is removed successfully
可以看到，驱动代码从配置空间读到的内容，和 lspci -x 显示的一致，说明驱动程序编写正确，并且通过 pci_ioremap_bar() 将 bar0 的地址（0xf0200000）映射到了虚拟内存地址（0x000000000e21ae12），之后就可以通过这个地址操作 bar0 寄存器了。
不过，这个 “PCI 驱动” 几乎不具备任何实际能力，这里仅作为一个演示，带领大家步入 PCI 驱动的大门。
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