Re: [PATCH] joydev.c: Digital joysticks on analog ports

[randy_dunlap <rdunlap@xenotime.net>]

On Thu, 7 Jul 2005 14:06:07 +0200 Vojtech Pavlik wrote:

| On Thu, Jul 07, 2005 at 01:14:58PM +0200, Thomas Richter wrote:
| > 
| > Hi folks, hi Vojtech,
| > 
| > the following is a patch to drivers/input/joydev.c and
| > include/linux/joystick.h that allows you to connect the "traditional"
| > digital joysticks for C64, Atari, Amiga... on analog input ports by
| > means of a minimalistic self- made adapter board ("ElCheapo",
| > schematics below). The patch converts the digital inputs to suitable
| > "analog" versions that are interpreted fine. The patch "as is" applies
| > to kernel 2.4.31, but it should work for other kernel versions as
| > well.
| > 
| > New kernel parameters for joydev: "digital = 1" sets all default input
| > modes to "digital" instead of analog.
| > 
| > The new ioctl JSIOCSDIGITAL for joydev allows to adjusts this
| > on the running driver.
| 
| Sorry, I have to reject this patch. 
| 
| First, you added support for the adapter to the wrong file - if
| anywhere, the logic should be either inside analog.c, or in a separate
| driver, which would be probably better.
| 
| Second, the 2.4 input layer is in bugfix-only mode now. Any new features
| can go only into 2.6.
| 
| Third - the ElCheapo interface is totally ugly. With just a few more
| component a real convertor, working as a real joystick is possible.
| 
| Fourth - we already have three drivers for these joystick (db9, gamecon
| and turbografx), all connected via trivial circuits to the parallel
| port.

5.  Fix indentation.

6.  Don't init static data to 0.


| > Greetings,
| > 	Thomas Richter
| > 
| > Patch for drivers/input/joydev.c:
| > 
| > /* snip */
| > 
| > --- ../linux-2.4.31/drivers/input/joydev.c	2003-06-13 16:51:34.000000000 +0200
| > +++ drivers/input/joydev.c	2005-07-06 22:37:21.000000000 +0200
| > @@ -65,6 +65,7 @@
| >  	struct JS_DATA_SAVE_TYPE glue;
| >  	int nabs;
| >  	int nkey;
| > +        int digital;
| >  	__u16 keymap[KEY_MAX - BTN_MISC];
| >  	__u16 keypam[KEY_MAX - BTN_MISC];
| >  	__u8 absmap[ABS_MAX];
| > @@ -84,6 +85,11 @@
| >  
| >  static struct joydev *joydev_table[JOYDEV_MINORS];
| >  
| > +static int digital = 0;
| > +
| > +MODULE_PARM(digital,"i");
| > +MODULE_PARM_DESC(digital,"if 1, handle digital joysticks via the 'ElCheapo' interface");
| > +
| >  MODULE_AUTHOR("Vojtech Pavlik <vojtech@suse.cz>");
| >  MODULE_DESCRIPTION("Joystick device driver");
| >  MODULE_LICENSE("GPL");
| > @@ -109,13 +115,68 @@
| >  	return value;
| >  }
| >  
| > +static int joydev_digital_event(struct js_event *ev,struct input_handle *handle,unsigned int type,
| > +				unsigned int code, int value)
| > +{
| > +  struct joydev *joydev = handle->private;
| > +
| > +  switch(type) {
| > +  case EV_KEY:
| > +    if (code < BTN_MISC || value == 2) return 0;
| > +    code = joydev->keymap[code - BTN_MISC];
| > +    switch(code) {
| > +    case 0:
| > +      ev->type   = JS_EVENT_AXIS;
| > +      ev->number = 1;
| > +      ev->value  = (value)?+32767:0;
| > +      break;
| > +    case 1:
| > +      ev->type   = JS_EVENT_AXIS;
| > +      ev->number = 0;
| > +      ev->value  = (value)?+32767:0;
| > +      break;
| > +    case 2:
| > +      ev->type   = JS_EVENT_AXIS;
| > +      ev->number = 1;
| > +      ev->value  = (value)?-32767:0;
| > +      break;
| > +    case 3:
| > +      ev->type   = JS_EVENT_AXIS;
| > +      ev->number = 0;
| > +      ev->value  = (value)?-32767:0;
| > +      break;
| > +    default:
| > +      ev->type   = JS_EVENT_BUTTON;
| > +      ev->number = code;
| > +      ev->value  = value;
| > +    }
| > +    break;
| > +  case EV_ABS:
| > +    if (joydev->absmap[code] == 0) {
| > +      ev->type   = JS_EVENT_BUTTON;
| > +      ev->number = 0;
| > +      if (joydev_correct(value, joydev->corr) >= 16384)
| > +	ev->value = 1;
| > +      else
| > +	ev->value = 0;
| > +    } else return 0;
| > +    break;
| > +  default:
| > +    return 0;
| > +  }
| > +  return 1;
| > +}
| > +
| >  static void joydev_event(struct input_handle *handle, unsigned int type, unsigned int code, int value)
| >  {
| >  	struct joydev *joydev = handle->private;
| >  	struct joydev_list *list = joydev->list;
| >  	struct js_event event;
| >  
| > -	switch (type) {
| > +	if (joydev->digital) {
| > +	  if (joydev_digital_event(&event,handle,type,code,value) == 0)
| > +	    return;
| > +	} else switch (type) {
| >  
| >  		case EV_KEY:
| >  			if (code < BTN_MISC || value == 2) return;
| > @@ -382,6 +443,8 @@
| >  				joydev->absmap[joydev->abspam[i]] = i;
| >  			}
| >  			return 0;
| > +	        case JSIOCSDIGITAL:
| > +		        return get_user(joydev->digital, (__u8 *)arg);
| >  		case JSIOCGAXMAP:
| >  			return copy_to_user((__u8 *) arg, joydev->abspam,
| >  						sizeof(__u8) * ABS_MAX) ? -EFAULT : 0;
| > @@ -450,6 +513,7 @@
| >  	joydev->handle.private = joydev;
| >  
| >  	joydev->exist = 1;
| > +	joydev->digital = digital;
| >  
| >  	for (i = 0; i < ABS_MAX; i++)
| >  		if (test_bit(i, dev->absbit)) {
| > 
| > /* snip */
| > 
| > Patch for include/linux/joystick.h:
| > 
| > /* snip */
| > 
| > --- ../linux-2.4.31/include/linux/joystick.h	2005-06-26 15:44:37.000000000 +0200
| > +++ include/linux/joystick.h	2005-07-06 22:37:36.000000000 +0200
| > @@ -70,6 +70,7 @@
| >  #define JSIOCGAXMAP		_IOR('j', 0x32, __u8[ABS_MAX])			/* get axis mapping */
| >  #define JSIOCSBTNMAP		_IOW('j', 0x33, __u16[KEY_MAX - BTN_MISC])	/* set button mapping */
| >  #define JSIOCGBTNMAP		_IOR('j', 0x34, __u16[KEY_MAX - BTN_MISC])	/* get button mapping */
| > +#define JSIOCSDIGITAL           _IOW('j', 0x35, __u8)                           /* set digital/analog flag */
| >  
| >  /*
| >   * Types and constants for get/set correction
| > 
| > /* snip */
| 
| -- 
| Vojtech Pavlik
| SuSE Labs, SuSE CR


---
~Randy