1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
|
;; -----------------------------------------------------------------------
;;
;; Copyright 2009 Intel Corporation; author: H. Peter Anvin
;;
;; This program is free software; you can redistribute it and/or modify
;; it under the terms of the GNU General Public License as published by
;; the Free Software Foundation, Inc., 53 Temple Place Ste 330,
;; Boston MA 02111-1307, USA; either version 2 of the License, or
;; (at your option) any later version; incorporated herein by reference.
;;
;; -----------------------------------------------------------------------
;;
;; serirq.inc
;;
;; Serial port IRQ code
;;
;; We don't know what IRQ, if any, we have, so map all of them...
;;
section .text16
bits 16
align 8
section .bss16
alignb 8
%assign n 0
%rep 16
section .text16
serstub_irq %+ n :
push dword [cs:oldirq %+ n]
jmp short irq_common
section .bss16
oldirq %+ n resd 1
%assign n n+1
%endrep
section .text16
irq_common:
pushf
push ax
push dx
mov dx,[cs:SerialPort]
add dx,5 ; DX -> LSR
in al,dx
test al,1 ; Received data
jnz .data
.done:
pop dx
pop ax
popf
retf ; Chain to next handler
.data:
push es
push di
mov ax,aux_seg + (aux.serial >> 4)
mov es,ax
mov di,[cs:SerialHead]
.loop:
mov dx,[cs:SerialPort] ; DX -> RDR
in al,dx
stosb
mov ah,[cs:FlowIgnore]
add dx,5 ; DX -> LSR
in al,dx
push ax
and al,ah
cmp al,ah
jne .drop
and di,serial_buf_size-1 ; Wrap around if necessary
cmp di,[cs:SerialTail] ; Would this cause overflow?
je .drop ; If so, just drop the data
mov [cs:SerialHead],di
.drop:
pop ax
test al,1 ; More data?
jnz .loop
.full:
pop di
pop es
jmp .done
section .bss16
;
; SerialIRQPort will generally track SerialPort, but will be 0 when an
; IRQ service is not installed.
;
SerialIRQPort resw 1 ; Serial port w IRQ service
SerialHead resw 1 ; Head of serial port rx buffer
SerialTail resw 1 ; Tail of serial port rx buffer
section .bss16
IRQMask resw 1 ; PIC IRQ mask status
section .text16
sirq_install:
pushad
call sirq_cleanup
; Save the old interrupt vectors
mov si,4*08h
mov di,oldirq0
mov cx,8
rep movsd
mov si,4*70h
mov cx,8
rep movsd
; Install new interrupt vectors
mov di,4*08h
mov cx,8
mov eax,serstub_irq0
.pic0:
stosd
add ax,serstub_irq1 - serstub_irq0
loop .pic0
mov di,4*70h
mov cx,8
.pic1:
stosd
add ax,serstub_irq1 - serstub_irq0
loop .pic1
mov bx,[SerialPort]
mov [SerialIRQPort],bx
lea dx,[bx+5] ; DX -> LCR
mov al,03h ; Clear DLAB (should already be...)
slow_out dx,al
lea dx,[bx+1] ; DX -> IER
mov al,1 ; Enable receive interrupt
slow_out dx,al
;
; Enable all ther interupt lines at the PIC. Some BIOSes
; only enable the timer interrupts and other interrupts
; actively in use by the BIOS.
;
in al,0xA1 ; Secondary PIC mask register
mov ah,al
in al,0x21 ; Primary PIC mask register
mov [IRQMask],ax
io_delay
xor ax,ax ; Remove all interrupt masks
out 0x21,al
out 0xA1,al
popad
ret
sirq_cleanup_nowipe:
pushad
push ds
push es
xor ax,ax
mov ds,ax
mov es,ax
mov bx,[SerialIRQPort]
and bx,bx
jz .done
lea dx,[bx+5] ; DX -> LCR
mov al,03h ; Clear DLAB (should already be...)
slow_out dx,al
lea dx,[bx+1] ; DX -> IER
xor ax,ax
slow_out dx,al ; Clear IER
; Restore PIC masks
mov ax,[IRQMask]
out 0x21,al
mov al,ah
out 0xA1,al
; Restore the original interrupt vectors
mov si,oldirq0
mov di,4*08h
mov cx,8
rep movsd
mov di,4*70h
mov cx,8
rep movsd
xor ax,ax
mov [SerialIRQPort],ax ; No active interrupt system
.done:
pop es
pop ds
popad
ret
sirq_cleanup:
call sirq_cleanup_nowipe
pushad
push es
; Just in case it might contain a password, erase the
; serial port receive buffer...
mov ax,aux_seg + (aux.serial >> 4)
mov es,ax
xor eax,eax
mov [cs:SerialHead],eax
mov cx,serial_buf_size >> 2
xor di,di
rep stosd
pop es
popad
ret
section .text16
|
