PCI子系统（三）- PCI设备驱动

这里拿linux/drivers/leds/leds-ss4200.c来做模板参考学习

---

注册struct pci_driver

static struct pci_driver nas_gpio_pci_driver = {
        .name = KBUILD_MODNAME,
        .id_table = ich7_lpc_pci_id,
        .probe = ich7_lpc_probe,
        .remove = ich7_lpc_remove,
};

static int __init nas_gpio_init(void)
{
	ret = pci_register_driver(&nas_gpio_pci_driver);

}

static void __exit nas_gpio_exit(void)
{
	pci_unregister_driver(&nas_gpio_pci_driver);
}
module_init(nas_gpio_init);
module_exit(nas_gpio_exit);

---

probe

使能PCI设备，读取PCI设备对应在CPU总线上的寄存器地址

/* ICH7 LPC/GPIO PCI Config register offsets */
#define PMBASE          0x040
#define GPIO_BASE       0x048
#define GPIO_CTRL       0x04c
#define GPIO_EN         0x010

/* The ICH7 GPIO register block is 64 bytes in size. */
#define ICH7_GPIO_SIZE  64

static int ich7_lpc_probe(struct pci_dev *dev, const struct pci_device_id *id)
{
	status = pci_enable_device(dev);
	status = pci_read_config_dword(dev, PMBASE, &g_pm_io_base);
	status = pci_read_config_dword(dev, GPIO_CTRL, &gc);
	status = pci_read_config_dword(dev, GPIO_BASE, &nas_gpio_io_base);
	gp_gpio_resource = request_region(nas_gpio_io_base, ICH7_GPIO_SIZE, KBUILD_MODNAME);
}

除了可以用pci_read_config_word读取pci设备的访问地址之外，一般是通过pci_resource_start(pci_dev, 0)，然后再通过request_region申请访问这块地址。

---

操作PCI设备

通过从PCI设备配置信息中读取的nas_gpio_io_base寄存器地址操作led

static void __nasgpio_led_set_attr(struct led_classdev *led_cdev, u32 port, u32 value)
{
        struct nasgpio_led *led = led_classdev_to_nasgpio_led(led_cdev);
        u32 gpio_out;

        gpio_out = inl(nas_gpio_io_base + port);
        if (value)
                gpio_out |= (1<<led->gpio_bit);
        else
                gpio_out &= ~(1<<led->gpio_bit);

        outl(gpio_out, nas_gpio_io_base + port);
}

---

参考文章

1. pci设备驱动

本文地址：https://blog.csdn.net/luckywang1103/article/details/85990349