在模块中读写pcie slot的寄存器状态

写了一个模块想模拟一下pcie slot的外部按钮事件，想法是通过改pcie插槽的寄存器的状态，然后有pciehp的中断/轮询机制来触发
对应的处理流程，可是实验过程中没有出现预期的结果...，功力尚浅～～


#include 
#include 
#include 
#include 


#define PCI_EXP_SLTSTA_PDS      0x0040  /* Presence Detect State */
#define PCI_EXP_SLTSTA_PDC      0x0008  /* Presence Detect Changed */
#define PCI_EXP_SLTSTA          26      /* Slot Status */
#define PCI_EXP_SLTCTL_PCC      0x0400  /* Power Controller Control */
#define POWER_OFF       PCI_EXP_SLTCTL_PCC
#define PCI_EXP_SLTCTL          24      /* Slot Control */
static struct pci_dev *dev;
static struct pci_bus *bus;
static int domain = 0x0000;
static int busnr = 0;
module_param(domain, int, 0644);
module_param(busnr, int, 0644);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("GuZheng [e-mail]");
static int __init pcie_conf_init(void)
{
        int retval = 0;
        u16 slot_ctrl;
        u16 slot_cmd;
        u16 cmd_mask;

        bus = pci_find_bus(domain, busnr);
        if (!bus) {
                printk("==can not get pci_bus==\\n");
                return -1;
        }
        printk("Succeed get pci bus:%s\\n", bus->name);

        dev = bus->self;
        if (!dev) {
                printk("==can not get dev==\\n");
                return -1;
        }

        retval = pcie_capability_read_word(dev, PCI_EXP_SLTCTL, &slot_ctrl);
        if (retval) {
                printk("%s can not read pcie register!\\n", __func__);
                return retval;
        }
        printk("Succeed read pcie slot register!\\n");
        cmd_mask = PCI_EXP_SLTCTL_PCC;
        slot_cmd = POWER_OFF;

        slot_ctrl &= ~cmd_mask;
        slot_ctrl |= (cmd_mask & slot_cmd);
        retval = pcie_capability_write_word(dev, PCI_EXP_SLTCTL, slot_ctrl);
        if (retval) {
                printk("%s can not read pcie register!\\n", __func__);
                return retval;
        }
        printk("Succeed write pcie slot register!\\n");
        return retval;
}

static void __exit pcie_conf_exit(void)
{
        printk("exit module!\\n");
        return;
}
module_init(pcie_conf_init);
module_exit(pcie_conf_exit);