Minimal device system, implement terminal device and libterminal

kernel/Flanterm/.gitignore

@@ -0,0 +1,2 @@
+*.d
+*.o

kernel/Flanterm/LICENSE

@@ -0,0 +1,22 @@
+Copyright (C) 2022-2026 Mintsuki and contributors.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are met:
+
+1. Redistributions of source code must retain the above copyright notice, this
+   list of conditions and the following disclaimer.
+
+2. Redistributions in binary form must reproduce the above copyright notice,
+   this list of conditions and the following disclaimer in the documentation
+   and/or other materials provided with the distribution.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
+ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

kernel/Flanterm/README.md

@@ -0,0 +1,43 @@
+# Flanterm
+
+Flanterm is a fast and reasonably complete terminal emulator with support for
+multiple output backends. Included is a fast framebuffer backend.
+
+### Quick usage
+
+To quickly set up and use a framebuffer Flanterm instance, it is possible to
+use the `flanterm_fb_init()` function as such:
+```c
+#include <flanterm.h>
+#include <flanterm_backends/fb.h>
+
+struct flanterm_context *ft_ctx = flanterm_fb_init(
+        NULL,
+        NULL,
+        framebuffer_ptr, width, height, pitch,
+        red_mask_size, red_mask_shift,
+        green_mask_size, green_mask_shift,
+        blue_mask_size, blue_mask_shift,
+        NULL,
+        NULL, NULL,
+        NULL, NULL,
+        NULL, NULL,
+        NULL, 0, 0, 1,
+        0, 0,
+        0
+    );
+```
+Where `framebuffer_ptr, width, height, pitch` and `{red,green,blue}_mask_{size,shift}`
+represent the corresponding info about the framebuffer to use for this given instance.
+
+The meaning of the other arguments can be found in `flanterm_backends/fb.h`.
+
+To then print to the terminal instance, simply use the `flanterm_write()`
+function on the given instance. For example:
+```c
+#include <flanterm.h>
+
+const char msg[] = "Hello world\n";
+
+flanterm_write(ft_ctx, msg, sizeof(msg));
+```

kernel/Flanterm/src.mk

@@ -0,0 +1,5 @@
+c += Flanterm/src/flanterm.c \
+		 Flanterm/src/flanterm_backends/fb.c
+
+o += Flanterm/src/flanterm.o \
+		 Flanterm/src/flanterm_backends/fb.o

kernel/Flanterm/src/.gitignore

@@ -0,0 +1 @@
+*.o

kernel/Flanterm/src/flanterm.h

@@ -0,0 +1,74 @@
+/* SPDX-License-Identifier: BSD-2-Clause */
+
+/* Copyright (C) 2022-2026 Mintsuki and contributors.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice,
+ *    this list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#ifndef FLANTERM_H
+#define FLANTERM_H 1
+
+#include <stdbool.h>
+#include <stddef.h>
+#include <stdint.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#define FLANTERM_CB_DEC           10
+#define FLANTERM_CB_BELL          20
+#define FLANTERM_CB_PRIVATE_ID    30
+#define FLANTERM_CB_STATUS_REPORT 40
+#define FLANTERM_CB_POS_REPORT    50
+#define FLANTERM_CB_KBD_LEDS      60
+#define FLANTERM_CB_MODE          70
+#define FLANTERM_CB_LINUX         80
+#define FLANTERM_CB_OSC           90
+
+#ifdef FLANTERM_IN_FLANTERM
+
+#include "flanterm_private.h"
+
+#else
+
+struct flanterm_context;
+
+#endif
+
+void flanterm_write (struct flanterm_context* ctx, const char* buf, size_t count);
+void flanterm_flush (struct flanterm_context* ctx);
+void flanterm_full_refresh (struct flanterm_context* ctx);
+void flanterm_deinit (struct flanterm_context* ctx, void (*_free) (void* ptr, size_t size));
+
+void flanterm_get_dimensions (struct flanterm_context* ctx, size_t* cols, size_t* rows);
+void flanterm_set_autoflush (struct flanterm_context* ctx, bool state);
+void flanterm_set_callback (struct flanterm_context* ctx,
+                            void (*callback) (struct flanterm_context*, uint64_t, uint64_t,
+                                              uint64_t, uint64_t));
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif

kernel/Flanterm/src/flanterm_backends/.gitignore

@@ -0,0 +1 @@
+*.o

kernel/Flanterm/src/flanterm_backends/fb.h

@@ -0,0 +1,76 @@
+/* SPDX-License-Identifier: BSD-2-Clause */
+
+/* Copyright (C) 2022-2026 Mintsuki and contributors.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice,
+ *    this list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#ifndef FLANTERM_FB_H
+#define FLANTERM_FB_H 1
+
+#include <stdbool.h>
+#include <stddef.h>
+#include <stdint.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#include "../flanterm.h"
+
+#ifdef FLANTERM_IN_FLANTERM
+
+#include "fb_private.h"
+
+#endif
+
+#define FLANTERM_FB_ROTATE_0   0
+#define FLANTERM_FB_ROTATE_90  1
+#define FLANTERM_FB_ROTATE_180 2
+#define FLANTERM_FB_ROTATE_270 3
+
+struct flanterm_context* flanterm_fb_init (
+    /* If _malloc and _free are nulled, use the bump allocated instance (1 use only). */
+    void* (*_malloc) (size_t size), void (*_free) (void* ptr, size_t size), uint32_t* framebuffer,
+    size_t width, size_t height, size_t pitch, uint8_t red_mask_size, uint8_t red_mask_shift,
+    uint8_t green_mask_size, uint8_t green_mask_shift, uint8_t blue_mask_size,
+    uint8_t blue_mask_shift, uint32_t* canvas,                /* If nulled, no canvas. */
+    uint32_t* ansi_colours, uint32_t* ansi_bright_colours,    /* If nulled, default. */
+    uint32_t* default_bg, uint32_t* default_fg,               /* If nulled, default. */
+    uint32_t* default_bg_bright, uint32_t* default_fg_bright, /* If nulled, default. */
+    /* If font is null, use default font and font_width and font_height ignored. */
+    void* font, size_t font_width, size_t font_height, size_t font_spacing,
+    /* If scale_x and scale_y are 0, automatically scale font based on resolution. */
+    size_t font_scale_x, size_t font_scale_y, size_t margin,
+    /* One of FLANTERM_FB_ROTATE_* values. */
+    int rotation);
+
+void flanterm_fb_set_flush_callback (struct flanterm_context* ctx,
+                                     void (*flush_callback) (volatile void* address,
+                                                             size_t length));
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif

kernel/Flanterm/src/flanterm_backends/fb_private.h

@@ -0,0 +1,127 @@
+/* SPDX-License-Identifier: BSD-2-Clause */
+
+/* Copyright (C) 2022-2026 Mintsuki and contributors.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice,
+ *    this list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#ifndef FLANTERM_FB_PRIVATE_H
+#define FLANTERM_FB_PRIVATE_H 1
+
+#ifndef FLANTERM_IN_FLANTERM
+#error "Do not use fb_private.h. Use interfaces defined in fb.h only."
+#endif
+
+#include <stdbool.h>
+#include <stddef.h>
+#include <stdint.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#define FLANTERM_FB_FONT_GLYPHS 256
+
+struct flanterm_fb_char {
+  uint32_t c;
+  uint32_t fg;
+  uint32_t bg;
+};
+
+struct flanterm_fb_queue_item {
+  size_t x, y;
+  struct flanterm_fb_char c;
+};
+
+struct flanterm_fb_context {
+  struct flanterm_context term;
+
+  void (*plot_char) (struct flanterm_context* ctx, struct flanterm_fb_char* c, size_t x, size_t y);
+  void (*flush_callback) (volatile void* address, size_t length);
+
+  size_t font_width;
+  size_t font_height;
+  size_t glyph_width;
+  size_t glyph_height;
+
+  size_t font_scale_x;
+  size_t font_scale_y;
+
+  size_t offset_x, offset_y;
+
+  volatile uint32_t* framebuffer;
+  size_t pitch;
+  size_t width;
+  size_t height;
+  size_t phys_height;
+  size_t bpp;
+
+  uint8_t red_mask_size, red_mask_shift;
+  uint8_t green_mask_size, green_mask_shift;
+  uint8_t blue_mask_size, blue_mask_shift;
+
+  int rotation;
+
+  size_t font_bits_size;
+  uint8_t* font_bits;
+  size_t font_bool_size;
+  bool* font_bool;
+
+  uint32_t ansi_colours[8];
+  uint32_t ansi_bright_colours[8];
+  uint32_t default_fg, default_bg;
+  uint32_t default_fg_bright, default_bg_bright;
+
+  size_t canvas_size;
+  uint32_t* canvas;
+
+  size_t grid_size;
+  size_t queue_size;
+  size_t map_size;
+
+  struct flanterm_fb_char* grid;
+
+  struct flanterm_fb_queue_item* queue;
+  size_t queue_i;
+
+  struct flanterm_fb_queue_item** map;
+
+  uint32_t text_fg;
+  uint32_t text_bg;
+  size_t cursor_x;
+  size_t cursor_y;
+
+  uint32_t saved_state_text_fg;
+  uint32_t saved_state_text_bg;
+  size_t saved_state_cursor_x;
+  size_t saved_state_cursor_y;
+
+  size_t old_cursor_x;
+  size_t old_cursor_y;
+};
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif

kernel/Flanterm/src/flanterm_private.h

@@ -0,0 +1,134 @@
+/* SPDX-License-Identifier: BSD-2-Clause */
+
+/* Copyright (C) 2022-2026 Mintsuki and contributors.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice,
+ *    this list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#ifndef FLANTERM_PRIVATE_H
+#define FLANTERM_PRIVATE_H 1
+
+#ifndef FLANTERM_IN_FLANTERM
+#error "Do not use flanterm_private.h. Use interfaces defined in flanterm.h only."
+#endif
+
+#include <stdbool.h>
+#include <stddef.h>
+#include <stdint.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#define FLANTERM_MAX_ESC_VALUES 16
+
+struct flanterm_context {
+  /* internal use */
+
+  size_t tab_size;
+  bool autoflush;
+  bool cursor_enabled;
+  bool scroll_enabled;
+  bool wrap_enabled;
+  bool origin_mode;
+  bool control_sequence;
+  bool escape;
+  bool osc;
+  bool osc_escape;
+  size_t osc_buf_i;
+  uint8_t osc_buf[256];
+  bool rrr;
+  bool discard_next;
+  bool bold;
+  bool bg_bold;
+  bool reverse_video;
+  bool dec_private;
+  bool insert_mode;
+  bool csi_unhandled;
+  uint64_t code_point;
+  size_t unicode_remaining;
+  uint8_t g_select;
+  uint8_t charsets[2];
+  size_t current_charset;
+  size_t escape_offset;
+  size_t esc_values_i;
+  size_t saved_cursor_x;
+  size_t saved_cursor_y;
+  size_t current_primary;
+  size_t current_bg;
+  size_t scroll_top_margin;
+  size_t scroll_bottom_margin;
+  uint32_t esc_values[FLANTERM_MAX_ESC_VALUES];
+  uint8_t last_printed_char;
+  bool last_was_graphic;
+  bool saved_state_bold;
+  bool saved_state_bg_bold;
+  bool saved_state_reverse_video;
+  bool saved_state_origin_mode;
+  bool saved_state_wrap_enabled;
+  size_t saved_state_current_charset;
+  uint8_t saved_state_charsets[2];
+  size_t saved_state_current_primary;
+  size_t saved_state_current_bg;
+
+  /* to be set by backend */
+
+  size_t rows, cols;
+
+  void (*raw_putchar) (struct flanterm_context*, uint8_t c);
+  void (*clear) (struct flanterm_context*, bool move);
+  void (*set_cursor_pos) (struct flanterm_context*, size_t x, size_t y);
+  void (*get_cursor_pos) (struct flanterm_context*, size_t* x, size_t* y);
+  void (*set_text_fg) (struct flanterm_context*, size_t fg);
+  void (*set_text_bg) (struct flanterm_context*, size_t bg);
+  void (*set_text_fg_bright) (struct flanterm_context*, size_t fg);
+  void (*set_text_bg_bright) (struct flanterm_context*, size_t bg);
+  void (*set_text_fg_rgb) (struct flanterm_context*, uint32_t fg);
+  void (*set_text_bg_rgb) (struct flanterm_context*, uint32_t bg);
+  void (*set_text_fg_default) (struct flanterm_context*);
+  void (*set_text_bg_default) (struct flanterm_context*);
+  void (*set_text_fg_default_bright) (struct flanterm_context*);
+  void (*set_text_bg_default_bright) (struct flanterm_context*);
+  void (*move_character) (struct flanterm_context*, size_t new_x, size_t new_y, size_t old_x,
+                          size_t old_y);
+  void (*scroll) (struct flanterm_context*);
+  void (*revscroll) (struct flanterm_context*);
+  void (*swap_palette) (struct flanterm_context*);
+  void (*save_state) (struct flanterm_context*);
+  void (*restore_state) (struct flanterm_context*);
+  void (*double_buffer_flush) (struct flanterm_context*);
+  void (*full_refresh) (struct flanterm_context*);
+  void (*deinit) (struct flanterm_context*, void (*) (void*, size_t));
+
+  /* to be set by client */
+
+  void (*callback) (struct flanterm_context*, uint64_t, uint64_t, uint64_t, uint64_t);
+};
+
+void flanterm_context_reinit (struct flanterm_context* ctx);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif

kernel/amd64/bootmain.c

@@ -6,6 +6,7 @@
 #include <amd64/msr-index.h>
 #include <amd64/msr.h>
 #include <aux/compiler.h>
+#include <device/device.h>
 #include <fs/vfs.h>
 #include <irq/irq.h>
 #include <libk/std.h>
@@ -45,6 +46,7 @@ void bootmain (void) {
   amd64_ioapic_init ();
   amd64_hpet_init ();
 
+  devices_init ();
   vfs_init ();
 
   vfs_create_mountpoint ("ramdisk", VFS_RAMDISKFS);

kernel/device/.gitignore

@@ -0,0 +1 @@
+*.o

kernel/device/device.c

@@ -0,0 +1,72 @@
+#include <device/device.h>
+#include <device/terminal.h>
+#include <libk/fieldlengthof.h>
+#include <libk/rbtree.h>
+#include <libk/std.h>
+#include <libk/string.h>
+#include <m/terminal_device.h>
+#include <mm/liballoc.h>
+#include <sync/spin_lock.h>
+
+static struct rb_node_link* device_tree = NULL;
+static spin_lock_t device_tree_lock;
+
+struct device* device_create (int id, device_op_func_t* ops, size_t ops_len,
+                              bool (*init) (void* arg), void (*fini) (void), void* arg) {
+  if (ops_len >= fieldlengthof (struct device, ops))
+    return NULL;
+
+  struct device* device = malloc (sizeof (*device));
+
+  if (device == NULL)
+    return NULL;
+
+  memset (device, 0, sizeof (*device));
+
+  device->id = id;
+  device->init = init;
+  device->fini = fini;
+  memcpy (device->ops, ops, ops_len * sizeof (device_op_func_t));
+
+  if (!device->init (arg)) {
+    free (device);
+    return NULL;
+  }
+
+  spin_lock (&device_tree_lock);
+  rbtree_insert (struct device, &device_tree, &device->device_tree_link, device_tree_link, id);
+  spin_unlock (&device_tree_lock);
+
+  return device;
+}
+
+void device_delete (struct device* device) {
+  spin_lock (&device_tree_lock);
+  spin_lock (&device->lock);
+
+  rbtree_delete (&device_tree, &device->device_tree_link);
+
+  spin_unlock (&device->lock);
+  spin_unlock (&device_tree_lock);
+
+  device->fini ();
+}
+
+struct device* device_find (int id) {
+  struct device* device = NULL;
+
+  spin_lock (&device_tree_lock);
+  rbtree_find (struct device, &device_tree, id, device, device_tree_link, id);
+  spin_unlock (&device_tree_lock);
+
+  return device;
+}
+
+void devices_init (void) {
+  {
+    device_op_func_t ops[] = {
+        [TERMINAL_PUTSTR] = &terminal_putstr,
+    };
+    device_create (1, ops, lengthof (ops), &terminal_init, &terminal_fini, NULL);
+  }
+}

kernel/device/device.h

@@ -0,0 +1,24 @@
+#ifndef _KERNEL_DEVICE_DEVICE_H
+#define _KERNEL_DEVICE_DEVICE_H
+
+#include <libk/rbtree.h>
+#include <sync/spin_lock.h>
+
+typedef int (*device_op_func_t) (void* a1, void* a2, void* a3, void* a4);
+
+struct device {
+  int id;
+  device_op_func_t ops[32];
+  spin_lock_t lock;
+  struct rb_node_link device_tree_link;
+  bool (*init) (void* arg);
+  void (*fini) (void);
+};
+
+struct device* device_create (int id, device_op_func_t* ops, size_t ops_len,
+                              bool (*init) (void* arg), void (*fini) (void), void* arg);
+struct device* device_find (int id);
+void device_delete (struct device* device);
+void devices_init (void);
+
+#endif // _KERNEL_DEVICE_DEVICE_H

kernel/device/src.mk

@@ -0,0 +1,5 @@
+c += device/device.c \
+		 device/terminal.c
+
+o += device/device.o \
+		 device/terminal.o

kernel/device/terminal.c

@@ -0,0 +1,44 @@
+#include <Flanterm/src/flanterm.h>
+#include <Flanterm/src/flanterm_backends/fb.h>
+#include <device/terminal.h>
+#include <libk/std.h>
+#include <limine/requests.h>
+#include <m/status.h>
+#include <mm/liballoc.h>
+#include <sys/debug.h>
+
+struct flanterm_context* ft_ctx;
+
+void* ft_malloc (size_t n) { return malloc (n); }
+
+void ft_free (void* ptr, size_t size) {
+  (void)size;
+  free (ptr);
+}
+
+bool terminal_init (void* arg) {
+  (void)arg;
+
+  struct limine_framebuffer_response* fb_r = limine_framebuffer_request.response;
+  struct limine_framebuffer* fb = fb_r->framebuffers[0];
+
+  ft_ctx = flanterm_fb_init (&ft_malloc, &ft_free, fb->address, fb->width, fb->height, fb->pitch,
+                             fb->red_mask_size, fb->red_mask_shift, fb->green_mask_size,
+                             fb->green_mask_shift, fb->blue_mask_size, fb->blue_mask_shift, NULL,
+                             NULL, NULL, NULL, NULL, NULL, NULL, NULL, 0, 0, 1, 0, 0, 0, 0);
+
+  return true;
+}
+
+void terminal_fini (void) {}
+
+int terminal_putstr (void* a1, void* a2, void* a3, void* a4) {
+  (void)a2, (void)a3, (void)a4;
+
+  char* string = (char*)a1;
+  size_t* len = (size_t*)a2;
+
+  flanterm_write (ft_ctx, string, *len);
+
+  return ST_OK;
+}

kernel/device/terminal.h

@@ -0,0 +1,8 @@
+#ifndef _KERNEL_DEVICE_TERMINAL_H
+#define _KERNEL_DEVICE_TERMINAL_H
+
+bool terminal_init (void* arg);
+void terminal_fini (void);
+int terminal_putstr (void* a1, void* a2, void* a3, void* a4);
+
+#endif // _KERNEL_DEVICE_TERMINAL_H

kernel/libk/fieldlengthof.h

@@ -0,0 +1,8 @@
+#ifndef _KERNEL_LIBK_FIELDLENGTHOF_H
+#define _KERNEL_LIBK_FIELDLENGTHOF_H
+
+#include <libk/lengthof.h>
+
+#define fieldlengthof(type, field) (lengthof (((type*)0)->field))
+
+#endif // _KERNEL_LIBK_FIELDLENGTHOF_H

kernel/src.mk

@@ -8,3 +8,5 @@ include irq/src.mk
 include proc/src.mk
 include syscall/src.mk
 include fs/src.mk
+include device/src.mk
+include Flanterm/src.mk

kernel/syscall/syscall.c

@@ -1,5 +1,7 @@
 #include <aux/compiler.h>
+#include <device/device.h>
 #include <libk/assert.h>
+#include <libk/fieldlengthof.h>
 #include <libk/std.h>
 #include <limine/requests.h>
 #include <m/status.h>
@@ -166,6 +168,55 @@ DEFINE_SYSCALL (sys_mutex_unlock) {
   return SYSRESULT (ST_OK);
 }
 
+/* int device_do (int device_id, int cmd, void* a1, void* a2, void* a3, void* a4) */
+DEFINE_SYSCALL (sys_device_do) {
+  struct limine_hhdm_response* hhdm = limine_hhdm_request.response;
+
+  int device_id = (int)a1;
+  int cmd = (int)a2;
+  uintptr_t ua1 = a3, ka1 = 0;
+  uintptr_t ua2 = a4, ka2 = 0;
+  uintptr_t ua3 = a5, ka3 = 0;
+  uintptr_t ua4 = a6, ka4 = 0;
+  uintptr_t out_paddr;
+
+  if (!(cmd >= 0 && cmd < (int)fieldlengthof (struct device, ops)))
+    return -ST_BAD_DEVICE_OP;
+
+  spin_lock (&proc->procgroup->lock);
+
+  out_paddr = mm_v2p (&proc->procgroup->pd, ua1);
+  if (out_paddr != 0)
+    ka1 = (uintptr_t)hhdm->offset + out_paddr;
+
+  out_paddr = mm_v2p (&proc->procgroup->pd, ua2);
+  if (out_paddr != 0)
+    ka2 = (uintptr_t)hhdm->offset + out_paddr;
+
+  out_paddr = mm_v2p (&proc->procgroup->pd, ua3);
+  if (out_paddr != 0)
+    ka3 = (uintptr_t)hhdm->offset + out_paddr;
+
+  out_paddr = mm_v2p (&proc->procgroup->pd, ua4);
+  if (out_paddr != 0)
+    ka4 = (uintptr_t)hhdm->offset + out_paddr;
+
+  spin_unlock (&proc->procgroup->lock);
+
+  struct device* device = device_find (device_id);
+
+  if (device == NULL)
+    return -ST_NOT_FOUND;
+
+  spin_lock (&device->lock);
+
+  int ret = device->ops[cmd]((void*)ka1, (void*)ka2, (void*)ka3, (void*)ka4);
+
+  spin_unlock (&device->lock);
+
+  return ret;
+}
+
 static syscall_handler_func_t handler_table[] = {
     [SYS_QUIT] = &sys_quit,
     [SYS_TEST] = &sys_test,
@@ -178,6 +229,7 @@ static syscall_handler_func_t handler_table[] = {
     [SYS_MUTEX_DELETE] = &sys_mutex_delete,
     [SYS_MUTEX_LOCK] = &sys_mutex_lock,
     [SYS_MUTEX_UNLOCK] = &sys_mutex_unlock,
+    [SYS_DEVICE_DO] = &sys_device_do,
 };
 
 syscall_handler_func_t syscall_find_handler (int syscall_num) {