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serenity/Kernel/Bus/USB/Drivers/USBDriver.h
Jesse Buhagiar a0dd6ec6b1 Kernel/USB: Add driver_init section
At any one given time, there can be an abitrary number of USB drivers in
the system. The way driver mapping works (i.e, a device is inserted, and
a potentially matching driver is probed) requires us to have
instantiated driver objects _before_ a device is inserted. This leaves
us with a slight "chicken and egg" problem. We cannot call the probe
function before the driver is initialised, but we need to know _what_
driver to initialise.

This section is designed to store pointers to functions that are called
during the last stage of the early `_init` sequence in the Kernel. The
accompanying macro in `USBDriver` emits a symbol, based on the driver
name, into this table that is then automatically called.

This way, we enforce a "common" driver model; driver developers are not
only required to write their driver and inherit from `USB::Driver`, but
are also required to have a free floating init function that registers
their driver with the USB Core.
2023-09-18 11:09:19 -06:00

39 lines
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C++

/*
* Copyright (c) 2023, Jesse Buhagiar <jesse.buhagiar@serenityos.org>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#pragma once
#include <AK/AtomicRefCounted.h>
#include <AK/Error.h>
#include <AK/NonnullRefPtr.h>
namespace Kernel::USB {
using DriverInitFunction = void (*)();
#define USB_DEVICE_DRIVER(driver_name) \
DriverInitFunction driver_init_function_ptr_##driver_name __attribute__((section(".driver_init"), used)) = &driver_name::init
class Device;
struct USBDeviceDescriptor;
class USBInterface;
class Driver : public AtomicRefCounted<Driver> {
public:
Driver(StringView name)
: m_driver_name(name)
{
}
virtual ~Driver() = default;
virtual ErrorOr<void> probe(USB::Device&) = 0;
virtual void detach(USB::Device&) = 0;
StringView name() const { return m_driver_name; }
protected:
StringView const m_driver_name;
};
}