[kernel] Add preliminary support for PS/2 mouse driver /dev/psaux

[ghaerr]

Requested and discussed in ghaerr/microwindows#109 (comment).

This PR takes @toncho11's initial PS/2 mouse driver and adapts it into the TTY infrastructure in ELKS. The driver is not tested on any real hardware nor emulator. The mouse driver is accessible from /dev/psaux and likely only supports the base 3-byte PS/2 protocol. I have tested the basic operation of the TTY infrastructure around the driver, which works. I doubt the driver works as-is though.

There are likely serious issues with this driver, noted within the source with FIXME comments. These include the following:

• PS/2 controller status bit 1 should be checked before writing data to it
• IRQ 12 is not likely enabled using the required 8042 command sequence
• Opening /dev/psaux without a PS/2 controller will likely hang the system
• IRQ 12 interrupts need to be disabled on the controller on mouse close or the system may crash

These will be further researched by @toncho11 and tested on copy.sh/v86.

For now, the driver is always compiled and included on IBM PC builds by having the CONFIG_MOUSE_PS2 define set in linuxmt/config.h.

There is further work to do in Nano-X and ELKS to automatically access this driver when MOUSE_TYPE=ps2. I will be adding those changes either within this PR or as follow ups. The ELKS mouse program will be included allowing for easier debugging by enabling a user to see mouse activity using ASCII print statements rather than inside a GUI where that is much harder.

[ghaerr]

The ELKS mouse command as well as the GUI paint program have both been updated to use this experimental PS/2 kernel mouse driver on /dev/psaux, when MOUSE_TYPE=ps2 in the environment.

Using mouse will greatly aid the ability to debug the kernel, since it can be run in a shell script or MOUSE_TYPE=ps2 mouse to display mouse movement in ASCII on the console, rather than inside a window system. Moving the mouse should display the button status and X,Y coordinates.

The Nano-X mouse driver has also been updated to automatically use the /dev/psaux port when MOUSE_TYPE=ps2. It already supported PS/2 mice so the rest of that driver is unchanged.

[rafael2k]

Wow, I think my modernish Thinkpad trackpad is PS2! I might be able to test this in real hardware. I'll double check

[tyama501]

Hello @ghaerr

I have tried fd1440-fat.img on FabGL/PCEmulator with PS2 mouse,
but it says can't open mouse.
Do I need any other setting?

Thank you.

[toncho11]

@tyama501 we must be sure that FabGL/PCEmulator provides / exposes the PS2 hardware (8042 controller) to ELKS. If you ever need a different board: https://www.olimex.com/Products/Retro-Computers/ESP32-SBC-FabGL/open-source-hardware

[toncho11]

I just saw that actually @ghaerr improved the driver. I personally am unable to test or work on it for the moment.

[tyama501]

Yes, I have used the latest one.

[ghaerr]

@tyama501 Are you running the standard IBM PC configuration, or PC-98? The /dev/psaux mouse is only compiled in on IBM PC right now. Also, @toncho11 is correct that the PS/2 mouse is actually implemented within the 8042 controller, so that must be emulated as well.

To try the PS/2 mouse on other architectures, add #define CONFIG_MOUSE_PS2 in config.h.

I can't figure out errno 22 (=EINVAL), the only place that is in the driver is in ioctl. Are you running the direct console, or something else? You might try making the following change to comment out the -EINVAL return in ioctl in the mouse driver to see if that makes any difference:

diff --git a/elks/arch/i86/drivers/char/mouse-ps2.c b/elks/arch/i86/drivers/char/mouse-ps2.c
index 8f9a6088..3e8659aa 100644
--- a/elks/arch/i86/drivers/char/mouse-ps2.c
+++ b/elks/arch/i86/drivers/char/mouse-ps2.c
@@ -144,7 +144,8 @@ static int ps2_ioctl(struct tty *tty, int cmd, char *arg)
     case TCSETSF:
         return 0;
     }
-    return -EINVAL;
+    //return -EINVAL;
+    return 0;
 }
 

Also add the line to see the ioctl being sent to mouse driver:

    printk("ioctl %04x\n", cmd);
    switch (cmd) {

You might also check ls -l /dev/psaux to make sure it exists as char device 4,32.

Thank you!

[tyama501]

I am using IBM fd1440-fat from github actions.

I assume the mouse is attached to the i8042.
It works on dos.

FabGL/examples/VGA/PCEmulator/machine.cpp at master · fdivitto/FabGL https://share.google/hCzL1IfeS3IEMt5bI

It seems it also uses INT.

I will the char dev although it is existing.

Thank you.

[ghaerr]

@tyama501 Can you send me a picture of the boot screen? I have tracked down the -EINVAL response on open and it appears it only occurs as the result of the inability for the PS/2 mouse driver to grab IRQ 12 for the mouse. It could be that the emulator thinks your system is PC/XT instead of PX/AT, in which case sys_caps does not have IRQ8TO15 capability.

This will show in the "PC/XT class cpu YY" or "PC/AT class CPU YY" line at boot. I would like to know whether your system shows PC/XT, PC/AT and the class cpu YY value.

[ghaerr]

@tyama501 I'm getting ahead of your test results, but looking at FabGL source it appears they emulate an 8086 CPU (https://github.com/fdivitto/FabGL/blob/master/src/emudevs/i8086.cpp) based on code from 8086tiny. They also emulate two 8259 PICs, enabling the to have interrupts 8-15. Normally, the PC/XT (8086-only) only has a single 8259 PIC, and ELKS assumes if the CPU is < 80286 (i.e. 8086) then the ability to use IRQs 8-15 is not possible. Meanwhile, FabGL also uses IRQ 12 within the 8042 emulation (https://github.com/fdivitto/FabGL/blob/master/src/emudevs/i8042.cpp) for the PS/2 mouse.

In order to make this work, we can either change ELKS to always allow IRQs 8-15 even when it finds an 8086 processor, or we could implement a syscaps= option in /bootopts, which would allow overriding the default sys_caps, which is 0 for 8086 and CAPS_ALL for 80286+. What do you think?

Here are the system capabilities that now settable at compile-time only in config.h, which override the rule above:

/*
 * System capabilities - configurable for ROM or custom installations.
 * Normally, all capabilities will be set if arch_cpu >= CPU_80286 (PC/AT),
 * except when SYS_CAPS is defined for custom installations or emulations.
 */
#define CAP_PC_AT       (CAP_IRQ8TO15|CAP_IRQ2MAP9)      /* PC/AT capabilities */
#define CAP_KBD_LEDS    0x04    /* has keyboard LEDs */
#define CAP_HD_IDE      0x08    /* can do hard drive IDE probes */
#define CAP_IRQ8TO15    0x10    /* has IRQ 8 through 15 */
#define CAP_IRQ2MAP9    0x20    /* map IRQ 2 to 9 */
#define CAP_ALL         0xFF    /* all capabilities if PC/AT only */

[ghaerr]

@tyama501, you should be able to test directly from the GitHub Actions downloads from the above PR, which aims to automatically fix this issue on FabGL and other emulators that implement a PS/2 mouse on IRQ 12 while emulating an 8086 CPU.

[tyama501]

Thank you! I will test again late this week.

[tyama501]

Hello @ghaerr

The ps2 mouse on the FabGL worked with the latest https://github.com/ghaerr/elks/actions/runs/21502723483

ELKS_ps2_FabGL.mp4

Thank you!