65X-DOS/include/kernel/device.h

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// SPDX-License-Identifier: MIT
//
// kernel/device.h
// Driver declarations.
//
// Copyright © 2024 Kyle J Cardoza <Kyle.Cardoza@icloud.com>
#pragma once
#ifdef __CALYPSI_CC__
#include <stdbool.h>
#include <stddef.h>
#include <stdint.h>
// This symbol determines the maximum number of device drivers which
// can be in memory.
#ifndef DEVICE_MAX
#define DEVICE_MAX 32
#endif
// This symbol determines the maximum number of device map entries which
// ca be in memory.
#ifndef DEVICE_MAP_MAX
#define DEVICE_MAP_MAX 32
#endif
// Forward declaration.
struct file;
// A device, in this context, is a code module which exposes a defined set
// of functions for interacting with files and file-like data. It is not specific
// as to the nature of the underlying data storage. It is equally valid for a
// device to use a block of RAM or a serial device as it is a hard drive
// or SD card.
//
// None of these functions are required to actually do anyting if it is not
// sensible for the kind of device being used; for example, it is not
// sensible for an inherently read-only device to support moving or
// renaming files.
typedef struct {
// Initialize the device.
int (*init)(void);
// Opens a file, given a pathname.
int (*open)(struct file *file);
// Closes an open file, given a unique ID.
int (*close)(struct file *file);
// Seeks within an open file, given a unique ID and a length.
int (*seek)(struct file *file, long length);
// Reads data from the specified file.
int (*read)(struct file *file, void *dest, size_t length);
// Writes data to the specified file.
int (*write)(struct file *file, void *src, size_t length);
// Perform driver-specific operations.
int (*ioctl)(struct file *file,
unsigned short operation,
void *arg);
// Creates the specified file given a pathname.
int (*create)(struct file *file);
// Copies the specified file using the specified names.
int (*copy)(struct file *src,
struct file *dest);
// Moves the specified file using the specified names.
int (*move)(struct file *src,
struct file *dest);
// Gets the size of the file.
int (*get_file_size)(struct file *file, size_t *size);
// Fills out the metadata in the specified file from the pathname
// in the provided file.
int (*init_file)(struct file *file);
} Device;
// The device map is a table that maps device names, such as SD0: or
// TTY2: to the device driver that manages the device.
struct device_map {
char *name;
unsigned short major_number;
unsigned short minor_number;
};
// The global table of device drivers.
extern Device *device[DEVICE_MAX];
// The global map of device names to device modules.
extern struct device_map *device_map[DEVICE_MAP_MAX];
// Initialize all the device drivers. This is called once, at boot.
// It protects itself against being called again without a reset.
void device_init_all(void);
// Binds a device name to a device.
int device_bind_name(char *name,
unsigned short major_number,
unsigned short minor_number);
// Unbinds a bound device name.
int device_unbind_name(char *name);
// Get a bound device by its name.
int device_get_by_name(char *name, Device **device);
#endif