SchOS/kernel/dev/mouse.c

#include "types.h"
#include "defs.h"
#include "gfx.h"
#include "irq.h"
#include "x86.h"
#include "traps.h"
#include "spinlock.h"
#include "sleeplock.h"
#include "fs.h"
#include "file.h"

#define KBD_S_STAT      0x64
#define KBD_S_DATA      0x60
#define KBD_C_WRITE     0xD4
#define MOUSE_ACK       0xFA

struct {
  struct spinlock lock;
  int x;
  int y;
  uint8 buttons;
} mouse_state;

static void
mouse_wait(int type)
{
  int timeout = 100000;
  if(type == 0){
    while(timeout-- && !(inb(KBD_S_STAT) & 0x01));
  } else {
    while(timeout-- && (inb(KBD_S_STAT) & 0x02));
  }
}

static void
mouse_write(uchar data)
{
  mouse_wait(1);
  outb(KBD_S_STAT, KBD_C_WRITE);
  mouse_wait(1);
  outb(KBD_S_DATA, data);
}

static uchar
mouse_read(void)
{
  mouse_wait(0);
  return inb(KBD_S_DATA);
}

static void
mouse_irq(void *arg)
{
  (void)arg;
  mouseintr();
}

// Move the pointer. Caller holds mouse_state.lock.
//
// Positive dy is *down*, matching both the screen and USB HID. The PS/2
// packet reports the opposite, which is why its caller negates first --
// there is one pointer and two protocols disagreeing about which way is up,
// and the conversion belongs at the edge rather than in here.
static void
mouse_move_locked(int dx, int dy)
{
  mouse_state.x += dx;
  mouse_state.y += dy;

  // Clamp to the screen that actually exists. These were the literals 800 and
  // 600, which was correct while that was the only mode the loader could set.
  // It is a boot-time choice now (press R), and at 1280x800 the pointer simply
  // stopped two thirds of the way across -- which reads as the cursor drifting
  // away from the host's, rather than as a clamp.
  int maxx = (int)gfx_width();
  int maxy = (int)gfx_height();
  if(maxx <= 0) maxx = 800;
  if(maxy <= 0) maxy = 600;

  if(mouse_state.x < 0) mouse_state.x = 0;
  if(mouse_state.y < 0) mouse_state.y = 0;
  if(mouse_state.x >= maxx) mouse_state.x = maxx - 1;
  if(mouse_state.y >= maxy) mouse_state.y = maxy - 1;
}

// The same pointer, moved by something that is not the PS/2 port. USB HID
// uses this; anything else that produces motion events should too.
void
mouse_inject(int dx, int dy, int buttons)
{
  acquire(&mouse_state.lock);
  mouse_state.buttons = buttons;
  mouse_move_locked(dx, dy);
  release(&mouse_state.lock);

  input_mouse(dx, dy, buttons);
}

// Put the pointer somewhere, rather than nudging it.
//
// The clamp is the same as the relative path's, and for the same reason: the
// screen size is a boot-time choice now. The coordinates arrive already scaled
// to pixels -- the HID driver does that, because it is the only place that
// knows the device's logical range.
void
mouse_set_abs(int x, int y, int buttons)
{
  int maxx = (int)gfx_width();
  int maxy = (int)gfx_height();
  if(maxx <= 0) maxx = 800;
  if(maxy <= 0) maxy = 600;

  if(x < 0) x = 0;
  if(y < 0) y = 0;
  if(x >= maxx) x = maxx - 1;
  if(y >= maxy) y = maxy - 1;

  acquire(&mouse_state.lock);
  mouse_state.buttons = buttons;
  mouse_state.x = x;
  mouse_state.y = y;
  release(&mouse_state.lock);

  input_mouse_abs(x, y, buttons);
}

void
mouseintr(void)
{
  static uchar buf[3];
  static int phase = 0;
  uchar status;

  status = inb(KBD_S_STAT);

  if(!(status & 0x01) || !(status & 0x20)){
    return;
  }

  uchar data = inb(KBD_S_DATA);

  acquire(&mouse_state.lock);

  if(phase == 0 && !(data & 0x08)){
    release(&mouse_state.lock);
    return; 
  }

  buf[phase++] = data;

  if(phase == 3){
    phase = 0;

    mouse_state.buttons = buf[0] & 0x07;
    int dx = (buf[0] & 0x10) ? (int)buf[1] - 256 : buf[1];
    int dy = (buf[0] & 0x20) ? (int)buf[2] - 256 : buf[2];

    // The overflow bits mean the delta saturated and is meaningless; moving
    // by it would throw the pointer across the screen.
    if(!(buf[0] & 0x40) && !(buf[0] & 0x80))
      mouse_move_locked(dx, -dy);
    else
      dx = dy = 0;

    release(&mouse_state.lock);

    // Outside the lock: input_report takes its own, and holding two at once
    // is how a lock ordering rule gets invented by accident.
    input_mouse(dx, -dy, buf[0] & 0x07);
    return;
  }

  release(&mouse_state.lock);
}

int get_mouse_x(void) {
  int x;
  acquire(&mouse_state.lock);
  x = mouse_state.x;
  release(&mouse_state.lock);
  return x;
}

int get_mouse_y(void) {
  int y;
  acquire(&mouse_state.lock);
  y = mouse_state.y;
  release(&mouse_state.lock);
  return y;
}

uint8 get_mouse_buttons(void) {
  uint8 b;
  acquire(&mouse_state.lock);
  b = mouse_state.buttons;
  release(&mouse_state.lock);
  return b;
}

int
mouseread(struct inode *ip, uint64 off, char *dst, int n)
{
  struct mouse_data m;
  int size = sizeof(struct mouse_data);

  if(n < size) {
    return -1;
  }

  m.x = get_mouse_x();
  m.y = get_mouse_y();
  m.buttons = get_mouse_buttons();

  memmove(dst, &m, size);

  return size;
}

void
mouseinit(void)
{
  initlock(&mouse_state.lock, "mouse");
  mouse_state.x = 400;
  mouse_state.y = 300;

  // No 8042 at all: the port floats and reads 0xFF. That is a machine with
  // USB input only -- most laptops and desktops built in the last few years,
  // whenever the firmware's legacy emulation is off -- and every bit set means
  // "output full" for ever, so the flush below never ended and boot stopped
  // here. There is no mouse to set up, so do not.
  if(inb(KBD_S_STAT) == 0xFF){
    kinfo("ps2: no controller; mouse not set up\n");
    return;
  }

  // Drain whatever the controller is holding. Bounded, because a controller
  // that keeps producing bytes is broken and still not a reason to hang.
  for(int i = 0; i < 1024 && (inb(KBD_S_STAT) & 0x01); i++)
    inb(KBD_S_DATA);

  mouse_wait(1);
  outb(KBD_S_STAT, 0xA8);

  mouse_wait(1);
  outb(KBD_S_STAT, 0x20);
  mouse_wait(0);
  uchar cb = inb(KBD_S_DATA);
  
  cb |= 0x02;
  cb |= 0x01;
  cb &= ~0x20;
  
  mouse_wait(1);
  outb(KBD_S_STAT, 0x60);
  mouse_wait(1);
  outb(KBD_S_DATA, cb);

  mouse_write(0xF6);
  mouse_read();

  mouse_write(0xF4);
  mouse_read();

  irq_register(IRQ_MOUSE, mouse_irq, 0, "ps2-mouse", 0);
}