再识PCI：一个PCI驱动实例

之前写了第一篇关于PCI的文章，当时只是作为入门的接触笔记，后来对PCI又研究了一下，主要包括PCI设备的扫描过程及PCI驱动注册过程。

本文主要给出一个PCI实例，并在内核中做很多的打印以便跟踪其过程。代码参考i2c-i801.c文件，在intel平台上试验。

对于学习，我想像力一向不好，只能靠笨方法来学习。

代码如下：

/**
 * @file   pci_driver_test.c
 * @author Late Lee 
 * @date   Fri Apr 24 20:21:19 2015
 * 
 * @brief  PCI驱动学习示例
 * 
 * @note  
 
 log PCI驱动注册过程：
[63909.555877] [++LL debug: 269 @ foo_init]: MARK...
[63909.555897] [++LL debug: 1268 @ __pci_register_driver]: MARK...
[63909.555901] [++LL debug: 153 @ driver_register]: start MARK...
[63909.555906] [++LL debug: 168 @ driver_register]: MARK add driver to bus...
[63909.555909] bus: 'pci': add driver foo_bus
[63909.555913] [++LL debug: 694 @ bus_add_driver]: MARK init and add driver: foo_bus...
[63909.555920] [++LL debug: 700 @ bus_add_driver]: MARK add tail to klis_drivers...
[63909.555924] [++LL debug: 703 @ bus_add_driver]: MARK...
[63909.555932] [++LL debug: 404 @ driver_probe_device]: bus: 'pci': driver_probe_device: matched device 0000:00:1f.0 with driver foo_bus
[63909.555936] [++LL debug: 287 @ really_probe]: bus: 'pci': really_probe: probing driver foo_bus with device 0000:00:1f.0
[63909.555944] [++LL debug: 305 @ really_probe]: ready probe bus: 0000:00:1f.0
[63909.555949] [++LL debug: 404 @ pci_device_probe]: 0000:00:1f.0 ready to call pci probe.(0x8086: 0xf1c)
[63909.555952] [++LL debug: 163 @ foo_probe]: Got LPC.
[63909.555973] [++LL debug: 212 @ foo_probe]: SPI flash base addr: 0xfed01000 map mem: 0xf8adc000
[63909.555977] [++LL debug: 216 @ foo_probe]: temp: 0x0 WPEN: 0 WPST: 0
[63909.555987] [++LL debug: 319 @ really_probe]: bus: 'pci': really_probe: bound device 0000:00:1f.0 to driver foo_bus
[63909.555992] [++LL debug: 404 @ driver_probe_device]: bus: 'pci': driver_probe_device: matched device 0000:00:1f.3 with driver foo_bus
[63909.555996] [++LL debug: 287 @ really_probe]: bus: 'pci': really_probe: probing driver foo_bus with device 0000:00:1f.3
[63909.556004] [++LL debug: 305 @ really_probe]: ready probe bus: 0000:00:1f.3
[63909.556007] [++LL debug: 404 @ pci_device_probe]: 0000:00:1f.3 ready to call pci probe.(0x8086: 0xf12)
[63909.556010] [++LL debug: 158 @ foo_probe]: Got SMBUS.
[63909.556151] [++LL debug: 200 @ foo_probe]: got SMBUS smba: 0x2000
[63909.556161] [++LL debug: 203 @ foo_probe]: read SMBC: 0x7
[63909.556169] [++LL debug: 319 @ really_probe]: bus: 'pci': really_probe: bound device 0000:00:1f.3 to driver foo_bus
[63909.556182] [++LL debug: 710 @ bus_add_driver]: create file uevent...
[63909.556204] [++LL debug: 178 @ driver_register]: end MARK...

SMBus IO端口和内存

[++LL debug: 248 @ foo_probe]: got SMBUS smba: 0x2000
[++LL debug: 251 @ foo_probe]: read SMBC: 0x7
[++LL debug: 255 @ foo_probe]: got SMBUS bar 0(0x10): 0x90705000

# lspci -s 00:1f.3 -xxx
00:1f.3 Class 0c05: Device 8086:0f12 (rev 11)
00: 86 80 12 0f 03 00 90 02 11 00 05 0c 00 00 00 00
10: 00 50 70 90 00 00 00 00 00 00 00 00 00 00 00 00
20: 01 20 00 00 00 00 00 00 00 00 00 00 86 80 70 72
30: 00 00 00 00 50 00 00 00 00 00 00 00 0a 02 00 00
40: 01 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
50: 01 00 03 00 08 00 00 00 00 00 00 00 00 00 00 00
60: 03 04 04 00 00 00 08 08 00 00 00 00 00 00 00 00
70: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
80: 04 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
90: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
a0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
b0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
c0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
d0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
e0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
f0: 00 00 00 00 00 00 00 00 1a 0f 11 01 03 01 00 00


bar0为内存地址：
cat /proc/iomem 
90705000-9070501f : 0000:00:1f.3


bar4为IO端口地址：
cat /proc/ioports  
2000-201f : 0000:00:1f.3
 */
 
#include 
#include        /**< printk() */
#include 

#include          /**< cdev_* */
#include 
#include         /**< copy_*_user */

#include         /**< size_t */
#include         /**< error codes */
#include 

#include 
#include           /**< pci... */

#ifndef LL_DEBUG
#define LL_DEBUG
#endif

#ifdef LL_DEBUG
/* KERN_INFO */
#define ll_debug(fmt, ...) printk(KERN_INFO "[++LL debug: %d @ %s]: " fmt, __LINE__, __func__, ##__VA_ARGS__)
#else
#define ll_debug(fmt, ...)
#endif

// #define TEST_CHAR
#ifdef TEST_CHAR
extern int foodrv_probe(void);
extern int foodrv_remove(void);
#endif

// SMBus Port
#define PCI_DEVICE_ID_INTEL_BAYTRAIL_SMBUS  0x0F12
// LPC: Bridge to Intel Legacy Block
#define PCI_DEVICE_ID_INTEL_BAYTRAIL_LPC    0x0F1C
// I211
#define E1000_DEV_ID_I211_COPPER  0x1539

// PCI标准寄存器，共64字节
#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_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 */
/*
 * Base addresses specify locations in memory or I/O space.
 * Decoded size can be determined by writing a value of
 * 0xffffffff to the register, and reading it back.  Only
 * 1 bits are decoded.
 */
#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 */
/* 0x35-0x3b are reserved */
#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标准寄存器 结束
///////////////////////////////////////////////////

/* SMBus 基地址在bar 4 */
#define SMBBAR        4

/* PCI Address Constants */
#define SMBCOM  0x004
#define SMBBA  0x014
#define SMBATPC  0x05B /* used to unlock xxxBA registers */
#define SMBHSTCFG 0x0E0
#define SMBSLVC  0x0E1
#define SMBCLK  0x0E2
#define SMBREV  0x008
/////////////////////////////////////////////////////////////////////////

// 这里是SMBUS io访问的地址
/* SMBus address offsets */
#define SMBHSTSTS(p)    (0 + (p)->smba)
#define SMBHSTCNT(p)    (2 + (p)->smba)
#define SMBHSTCMD(p)    (3 + (p)->smba)
#define SMBHSTADD(p)    (4 + (p)->smba)
#define SMBHSTDAT0(p)   (5 + (p)->smba)
#define SMBHSTDAT1(p)   (6 + (p)->smba)
#define SMBBLKDAT(p)    (7 + (p)->smba)
#define SMBPEC(p)       (8 + (p)->smba)        /* ICH3 and later */
#define SMBAUXSTS(p)    (12 + (p)->smba)    /* ICH4 and later */
#define SMBAUXCTL(p)    (13 + (p)->smba)    /* ICH4 and later */

#define SMBSMBC(p)      (0xF + (p)->smba)

//////////////////////////////////////////////////////////////////////////
// LPC
/* PCI config registers in LPC bridge. LPC桥(这是一个PCI设备)上的外设偏移地址*/
#define REVID  0x08
#define ABASE  0x40
#define PBASE  0x44
#define GBASE  0x48
#define IOBASE  0x4c
#define IBASE  0x50
#define SBASE  0x54 // SPI的
#define MPBASE  0x58
#define PUBASE  0x5c
#define UART_CONT 0x80
#define RCBA  0xf0

//////////////////////////////////////////////////////////////////////////

struct foo_priv {
    u8 *name;
    int type;
    u32 smba;
    u32 mem;
    struct pci_dev *pci_dev;
    
};

static const struct pci_device_id foo_ids[] = {
    { PCI_DEVICE(PCI_VENDOR_ID_INTEL, PCI_DEVICE_ID_INTEL_BAYTRAIL_SMBUS) },
    { PCI_DEVICE(PCI_VENDOR_ID_INTEL, PCI_DEVICE_ID_INTEL_BAYTRAIL_LPC) },
    { PCI_DEVICE(PCI_VENDOR_ID_INTEL, E1000_DEV_ID_I211_COPPER) }, // 不懂为何，这个认不出
    { 0, }
};

/*
会调用2次，由PCI总线根据本驱动的id来决定
*/
static int foo_probe(struct pci_dev *dev, const struct pci_device_id *id)
{
    unsigned char temp;
    int err;
    struct foo_priv *priv;

    ll_debug("MARK Start of probe....\n");
    priv = kzalloc(sizeof(*priv), GFP_KERNEL);
    if (!priv)
        return -ENOMEM;

    priv->pci_dev = dev;
    switch (dev->device) {
    case PCI_DEVICE_ID_INTEL_BAYTRAIL_SMBUS: // 0000:00:1f.3
        ll_debug("Got SMBUS.\n");
        priv->name = "SMBUS";
        priv->type = 0;
        break;
    case PCI_DEVICE_ID_INTEL_BAYTRAIL_LPC: // 0000:00:1f.0
        ll_debug("Got LPC.\n");
        priv->name = "LPC";
        priv->type = 1;
        break;
    case E1000_DEV_ID_I211_COPPER: // 0000:01:00.0
        ll_debug("Got I211.\n");
        priv->name = "I211";
        priv->type = 2;
        break;
    default:
        priv->name = "Unknown";
        break;
    }

    err = pci_enable_device(dev); // 使能PCI设备
    if (err) {
        dev_err(&dev->dev, "Failed to enable SMBus PCI device (%d)\n",
            err);
        goto exit;
    }

    /* 从SMBus手册知，偏移量0x20为bar 4，5~15比特为IO基地址
    最低位为只读，值为1，表示SMB逻辑为IO映射(如手工读则要将基地址移位)
    但pci_resource_start返回的是正确的地址，可直接使用
    */
    if (priv->type == 0) {
        priv->smba = (u32)pci_resource_start(dev, SMBBAR);  // io bar
        if (!priv->smba) {
            dev_err(&dev->dev, "SMBus base address uninitialized, "
                "upgrade BIOS\n");
            err = -ENODEV;
            goto exit;
        }
#if 0
        err = pci_request_region(dev, SMBBAR, priv->name);
        if (err) {
            dev_err(&dev->dev, "Failed to request SMBus region "
                "0x%x-0x%Lx\n", priv->smba,
                (unsigned long long)pci_resource_end(dev, SMBBAR));
            goto exit;
        }
#endif
        ll_debug("got %s smba: 0x%x\n", priv->name, priv->smba);
        // 这是测试0xf寄存器的值，默认为7
        temp = inb_p(SMBSMBC(priv));
        ll_debug("read SMBC: 0x%x\n", temp);
        
        // 读bar0
        priv->smba = (u32)pci_resource_start(dev, 0); // memory bar
        ll_debug("got %s bar 0(0x10): 0x%x\n", priv->name, priv->smba);
    }

    // LPC桥的BAR没有赋值，读的话全为0
    // 但其上有许多外设的基地址，要根据偏移量来计算，见上面的宏定义
    if (priv->type == 1)
    {
        pci_read_config_dword(priv->pci_dev, SBASE, &priv->smba);
        priv->smba &= ~0x1FF; // 为何要对齐？
        priv->mem = (u32)ioremap(priv->smba, 4);
        ll_debug("SPI flash base addr: 0x%x map mem: 0x%x\n", priv->smba, priv->mem);
        
        // 读个寄存器试试
        temp = readl((void*)(priv->mem+0xF8));
        ll_debug("temp: 0x%x WPEN: %d WPST: %d\n", temp, (temp>>7)&0x1, (temp>>6)&0x1);

        #if 0
        int i;
        for (i = 0x10; i < 0x90; i+=4) {
            temp = readl((void*)(priv->mem+i));
            ll_debug("reg[%x] value: 0x%x\n", i, temp);
        }
        #endif
    }
    if (priv->type == 2)
    {
        priv->smba = (u32)pci_iomap(priv->pci_dev, 0, 0);
        ll_debug("I211 base addr: 0x%x\n", priv->smba);
    }

    pci_set_drvdata(dev, priv);

#ifdef TEST_CHAR
    // 这里可以注册cdev设备
    if (priv->type == 0)
        foodrv_probe();
#endif

    return 0;

exit:
    kfree(priv);
    return err;
}

static void foo_remove(struct pci_dev *dev)
{
    struct foo_priv *priv = pci_get_drvdata(dev);

    ll_debug("remove %s\n", priv->name);

    kfree(priv);

#ifdef TEST_CHAR
    if (priv->type == 0)
        foodrv_remove();
#endif
}

#define foo_suspend NULL
#define foo_resume NULL

static struct pci_driver foo_driver = {
    .name        = "foo_bus",
    .id_table    = foo_ids,
    .probe        = foo_probe,
    .remove        = foo_remove,
    //.suspend    = foo_suspend,
    //.resume        = foo_resume,
};

static int __init foo_init(void)
{
    ll_debug("+++++++++++++++++++++++++++Start of Test...\n");
    return pci_register_driver(&foo_driver);
}

static void __exit foo_exit(void)
{
    ll_debug("MARK...\n");
    pci_unregister_driver(&foo_driver);
    
    ll_debug("+++++++++++++++++++++++++++End of Exit...\n");
}

module_init(foo_init);
module_exit(foo_exit);

MODULE_AUTHOR("Jim Kent");
MODULE_DESCRIPTION("SMBus driver");
MODULE_LICENSE("GPL");

本文基于Intel芯片，手册地址：http://www.intel.com/content/www/us/en/embedded/products/bay-trail/atom-e3800-family-datasheet.html

李迟 5.6 中午