flashrom

The first thing that came to my mind is something like that:

static int atahpt_toggle_flash_access(struct atahpt_data *data, int toggle)
{
    uint32_t reg32 = 0;

    if (toggle) {
        data->flash_access = pci_read_long(data->dev, REG_FLASH_ACCESS);
        reg32 = BIT(BIT_FLASH_ACCESS);
    }

    reg32 |= data->flash_access;

    pci_write_long(data->dev, REG_FLASH_ACCESS, reg32);
    return 0;
}