SchOS/kernel/drivers/registry.c

// The driver registry.
//
// One table, one line per driver. This is the same shape as
// kernel/sys/table.inc and kernel/dev/cdev.c's devsw: a single place that
// lists what exists, so a driver cannot be half-registered.
//
// It is a plain array rather than the linker-section trick a bigger kernel
// would use (a __attribute__((section(".drivers"))) entry per driver, walked
// between __start_ and __stop_ symbols). That approach lets a driver register
// itself by existing, which is genuinely nicer -- but it also means the list
// of what is in your kernel is not written down anywhere you can read, and
// a driver silently dropped by the linker looks exactly like one that was
// never written. At this size, being able to read the list wins.
//
// To add a driver: write kernel/drivers/<name>.c exporting a struct
// pci_driver, declare it here, and add it to the array and to the Makefile's
// KERN_DRIVERS.

#include "types.h"
#include "defs.h"
#include "param.h"
#include "spinlock.h"
#include "sleeplock.h"
#include "fs.h"
#include "file.h"
#include "pci.h"

#include "usb.h"
#include "device.h"

extern const struct pci_driver vga_pci_driver;
extern const struct pci_driver xhci_driver;
extern const struct pci_driver virtio_gpu_driver;
extern const struct pci_driver e1000_driver;

// Order matters here in one respect: virtio-gpu is offered the bus before the
// VBE framebuffer driver, so that on a machine with both, the device with real
// mode setting and an explicit flush wins the display class. vga_pci still
// claims the stdvga card underneath, which is what the boot splash and the
// text console are drawn on.
static const struct pci_driver *drivers[] = {
    &virtio_gpu_driver,
    &vga_pci_driver,
    &e1000_driver,
    &xhci_driver,
};

void
pci_bind_all(void)
{
  for (unsigned i = 0; i < sizeof(drivers) / sizeof(drivers[0]); i++)
    pci_bind(drivers[i]);
}

// USB class drivers, same arrangement and for the same reason. These are not
// found on the PCI bus -- they are offered a device by the USB core once its
// interface descriptor has been read -- but a driver you cannot find in a
// list is a driver nobody knows is there, whichever bus it sits on.
//
// To add one: write kernel/drivers/usb_<name>.c exporting a struct
// usb_driver, declare it here, add it to the array and to KERN_DRIVERS.

extern const struct usb_driver usb_hid_driver;
extern const struct usb_driver usb_storage_driver;
extern const struct usb_driver usb_hub_driver;

static const struct usb_driver *usb_drivers[] = {
    &usb_hid_driver,
    &usb_storage_driver,
    &usb_hub_driver,
};

int usb_offer(const struct usb_driver *, struct usb_dev *);

void
usb_bind_all(struct usb_dev *dev)
{
  for (unsigned i = 0; i < sizeof(usb_drivers) / sizeof(usb_drivers[0]); i++)
    if (usb_offer(usb_drivers[i], dev)) {
      // Same as the PCI path: publish it in the bus-agnostic list so that
      // "what is attached" has one answer covering every bus. Class comes from
      // the driver that claimed it rather than the USB class code, because a
      // driver knows what it made of the device and the descriptor only says
      // what the device claims to be.
      const char *n = usb_drivers[i]->name;
      struct device *d = device_add(n, DEVBUS_USB, usb_drivers[i]->devclass, n);
      if (d)
        device_set_desc(d, usb_drivers[i]->name);
      return;
    }
}

// Devices that are not enumerated by any bus -- they are simply known to be
// there on a PC, and the driver pokes fixed I/O ports to find out whether it
// is right. Listing them matters because a device manager that shows the
// graphics card but not the keyboard is not showing the machine.
//
// Registered here rather than inside each driver's init so that the whole set
// is visible in one place, which is the same reasoning as the driver arrays
// above.
void
platform_register_devices(uint64 fb_addr)
{
  struct device *d;

  // The framebuffer first, before anything that might want to draw. It is a
  // driver call, and this file is where driver names belong -- main() used to
  // call vga_init() directly, which put one display driver's name in the
  // kernel's startup path and would have needed editing to boot on a machine
  // whose framebuffer came from anywhere else.
  vga_fb_init(fb_addr);

  if ((d = device_add("kbd", DEVBUS_PLATFORM, DEVCLASS_INPUT, "ps2kbd")))
    device_set_desc(d, "PS/2 keyboard");
  if ((d = device_add("mouse", DEVBUS_PLATFORM, DEVCLASS_INPUT, "ps2mouse")))
    device_set_desc(d, "PS/2 mouse");
  if ((d = device_add("uart", DEVBUS_PLATFORM, DEVCLASS_OTHER, "uart8250")))
    device_set_desc(d, "16550 serial port");
  if ((d = device_add("ide", DEVBUS_PLATFORM, DEVCLASS_STORAGE, "ide")))
    device_set_desc(d, "ATA disk controller");
}