152 lines
4.1 KiB
ArmAsm
152 lines
4.1 KiB
ArmAsm
;----------------------------------------------------------------
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;Keyboard interface driver for Z8C
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;Controller used: vt82c42
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;Datasheet: http://www.s100computers.com/My%20System%20Pages/MSDOS%20Board/vt82c42%20PC%20Keyboard%20conrtroller.pdf
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;by Dennis Gunia (04/2022)
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;----------------------------------------------------------------
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;================================================================
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; I/O registers
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;================================================================
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CS_VT82C42_DATA .EQU 0xF0
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CS_VT82C42_CTRL .EQU 0xF1
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;================================================================
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; I/O access functions
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;================================================================
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keyboard_init:
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ld a, 0xA7 ;Disable Mouse
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out (CS_VT82C42_CTRL), A
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ld a, 0xAD ;Disable Keyboard
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out (CS_VT82C42_CTRL), A
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_keyboard_init_flush_buffer:
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in a,(CS_VT82C42_DATA) ;Read buffer
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in a,(CS_VT82C42_CTRL) ;Read status byte
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bit 0,a ;Test if buffer is empty
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jr nz, _keyboard_init_flush_buffer
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;buffer is now flushed. Now set the Controller Configuration Byte
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ld a, 0x60 ;next byte is command byte register write
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ld b, 11111100b ;Disable bits 0,1,6 (disable IRQ and Translation)
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call keyb_cmd_wr
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;Perform Controller Self Test
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ld a, 0xAA
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call keyb_cmd_rd
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cp 0x55
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jr nz, _keyboard_init_failed
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;Perform Interface Tests
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ld a, 0xAB
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call keyb_cmd_rd
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or a
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jr nz, _keyboard_init_failed
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;Enable Devices
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ld a,0xAE
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out (CS_VT82C42_CTRL), A
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call keyb_wait_ibf_empty
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;Test if device is present Devices
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ld a,0xEE
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out (CS_VT82C42_DATA), A ;Send echo to keboard (0xEE command)
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call keyb_wait_ibf_empty
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call keyb_wait_obf
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in a,(CS_VT82C42_DATA)
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cp a, 0xEE
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jr z, _keyboard_init_okay ; 0xFC -> Success. Init done!
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;Else device error
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ld hl, [STR_keyboard_init_failed]
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call print_str
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ret
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_keyboard_init_failed:
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LD HL, [STR_keyboard_init_err]
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CALL print_str
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RET
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_keyboard_init_dev_missing:
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LD HL, [STR_keyboard_init_missing]
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CALL print_str
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RET
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_keyboard_init_okay:
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LD HL, [STR_keyboard_init_okay]
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CALL print_str
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RET
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keyb_cmd_enable:
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ld a, 0xF4
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call keyb_wr_wait_ack
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ld a, 0xED
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call keyb_wr_wait_ack
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ld a, 0x02
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call keyb_wr_wait_ack
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ret
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keyb_enable_int:
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ld a, 0x60 ;next byte is command byte register write
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ld b, 00000001b ;Disable bits 0,1,6 (disable IRQ and Translation)
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call keyb_cmd_wr
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_keyb_enable_int_flush_buffer:
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in a,(CS_VT82C42_DATA) ;Read buffer
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in a,(CS_VT82C42_CTRL) ;Read status byte
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bit 0,a ;Test if buffer is empty
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jr nz, _keyb_enable_int_flush_buffer
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ret
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; a contains command
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; b conatins data
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keyb_cmd_wr:
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out (CS_VT82C42_CTRL),a ;write command byte
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ld a, b
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out (CS_VT82C42_DATA),a
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ret
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; a contains command
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; a returns data
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keyb_cmd_rd:
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out (CS_VT82C42_CTRL),a ;write command byte
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_keyb_cmd_rd_l1:
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in a, (CS_VT82C42_CTRL) ;read status
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call print_a_hex
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rra
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jr nc, _keyb_cmd_rd_l1 ;wait until OBF is set (data avail)
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in a, (CS_VT82C42_DATA)
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ret
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keyb_wait_ibf_empty:
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in a, (CS_VT82C42_CTRL) ;read status
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rra
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rra
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jr c, keyb_wait_ibf_empty ;if IBF, wait
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ret
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keyb_wait_obf:
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in a, (CS_VT82C42_CTRL) ;read status
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rra
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jr nc, keyb_wait_obf ;if IBF, wait
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ret
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; a data
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; z is 0 if success
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keyb_wr_wait_ack:
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out (CS_VT82C42_DATA),a ;write command byte
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call keyb_wait_obf ;wait until sent
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_keyb_wr_wait_ack_l1: ;wait for reponse
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in a, (CS_VT82C42_CTRL) ;read status
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bit 1,a ;check input buffer full
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jr nz, _keyb_wr_wait_ack_l1
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in a, (CS_VT82C42_DATA)
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cp 0xFA
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ret
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;Status message strings
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STR_keyboard_init_okay:
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.BYTE "PS/2 Keyboard initialized.",0
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STR_keyboard_init_err:
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.BYTE "PS/2 Controller error! System HALT!",0
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STR_keyboard_init_failed:
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.BYTE "PS/2 Keyboard error! System HALT!",0
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STR_keyboard_init_missing:
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.BYTE "PS/2 no keyboard found!",0
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