Skip to content

HTTPS clone URL

Subversion checkout URL

You can clone with HTTPS or Subversion.

Download ZIP
Fetching contributors…

Cannot retrieve contributors at this time

400 lines (316 sloc) 12.164 kb
;;; Serial - interrupt driven serial I/O
;;;
;;; Copyright (c) 2009 Openmoko Inc.
;;;
;;; Authors Christopher Hall <hsw@openmoko.com>
;;;
;;; Redistribution and use in source and binary forms, with or without
;;; modification, are permitted provided that the following conditions are
;;; met:
;;;
;;; 1. Redistributions of source code must retain the above copyright
;;; notice, this list of conditions and the following disclaimer.
;;;
;;; 2. Redistributions in binary form must reproduce the above copyright
;;; notice, this list of conditions and the following disclaimer in
;;; the documentation and/or other materials provided with the
;;; distribution.
;;;
;;; THIS SOFTWARE IS PROVIDED BY THE CONTRIBUTORS ``AS IS'' AND ANY
;;; EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
;;; IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
;;; PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE CONTRIBUTORS BE LIABLE
;;; FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
;;; CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
;;; SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
;;; BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
;;; WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE
;;; OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN
;;; IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
.include "regs.inc"
;;; register usage
;;; r0 .. r3 must be preserved
;;; r4 result low
;;; r5 result high
;;; r6 .. r9 arguments 1..4
;;; r10 ..r14 reserved
;;; r15 __dp value
.section .bss
;;; buffer size = 2^n is conveient for modulo operation
BufferSize = 2048
;;; buffer is full if: (write + 1) mod size == read
;;; buffer is full if: write == read
RxBuffer:
.space BufferSize
RxRead:
.long 0
RxWrite:
.long 0
TxBuffer:
.space BufferSize
TxRead:
.long 0
TxWrite:
.long 0
.section .text
;;; wait wor serial output ready
;;; input:
;;; output:
;;; r4 = true if space in buffer, false if buffer is full
;;; r5 = address of TxWrite
;;; r6 = *NOT CHANGED* (will be byte to put)
;;; r7 = TxRead
;;; r8 = TxWrite (offset of byte to store)
;;; r9 = TxWrite + 1 (next free space)
.global Serial_PutReady
Serial_PutReady:
xld.w %r7, TxRead
xld.w %r5, TxWrite
ld.w %r7, [%r7] ; read
ld.w %r8, [%r5] ; write
ld.w %r9, %r8
add %r9, 1 ; write + 1
xand %r9, (BufferSize - 1) ; mod buffer size
cmp %r7, %r9 ; read == write ?
jreq Serial_PutReady_buffer_full
ld.w %r4, 1 ; TRUE => buffer is not full
ret
Serial_PutReady_buffer_full:
ld.w %r4, 0 ; FALSE => buffer is full
ret
;;; print a character
;;; input:
;;; r6 = char
;;; output:
;;; temporary:
;;; r4..r9
.global Serial_PutChar
Serial_PutChar_wait:
xcall suspend ; suspend until buffer space available
Serial_PutChar:
call Serial_PutReady ; wait for buffer space
or %r4, %r4
jreq Serial_PutChar_wait
xld.w %r4, TxBuffer ; buffer
add %r4, %r8 ; buffer + offset
ld.b [%r4], %r6 ; store byte
xld.w %r4, R8_INT_ESIF01
DISABLE_INTERRUPTS
ld.ub %r8, [%r4]
xand %r8, ESTX0 ; is Tx0 interrupt enabled
jrne Serial_PutChar_l1
ld.ub %r8, [%r4]
xoor %r8, ESTX0 ; enable Tx0 interrupt
ld.b [%r4], %r8
xld.w %r5, R8_EFSIF0_TXD
ld.b [%r5], %r6
jp Serial_PutChar_l2
Serial_PutChar_l1:
ld.w [%r5], %r9 ; update TxWrite
Serial_PutChar_l2:
ENABLE_INTERRUPTS
ret
;;; see if input is available
;;; input:
;;; output:
;;; r4 = 0 => not ready
;;; 1 => ready
;;; r5 = offset of byte to read
;;; r6 = address of RxRead
;;; temporary:
.global Serial_InputAvailable
Serial_InputAvailable:
xld.w %r6, RxRead
xld.w %r4, RxWrite
ld.w %r5, [%r6] ; read
ld.w %r4, [%r4] ; write
cmp %r5, %r4 ; read == write ?
jreq Serial_InputAvailable_buffer_empty
ld.w %r4, 1 ; TRUE => buffer is not empty
ret
Serial_InputAvailable_buffer_empty:
ld.w %r4, 0 ; FALSE => buffer is empty
ret
;;; read a character
;;; input:
;;; output:
;;; r4 = char
.global Serial_GetChar
Serial_GetChar_wait:
xcall suspend ; suspend until more input
Serial_GetChar:
call Serial_InputAvailable
or %r4, %r4
jreq Serial_GetChar_wait
xld.w %r4, RxBuffer
add %r4, %r5
ld.ub %r4, [%r4]
add %r5, 1
xand %r5, (BufferSize - 1)
ld.w [%r6], %r5 ; update RxRead
ret
;;; flush input buffer
;;; input:
;;; output:
.global Serial_FlushInput
Serial_FlushInput:
xld.w %r4, RxRead
xld.w %r5, RxWrite
ld.w %r6, 0
DISABLE_INTERRUPTS
ld.w [%r4], %r6
ld.w [%r5], %r6
ENABLE_INTERRUPTS
ret
;;; initialisation
;;; input:
;;; output:
.global Serial_initialise
Serial_initialise:
xld.w %r6, Vector_Serial_interface_Ch_0_Receive_buffer_full
xld.w %r7, Serial_RxInterrupt
xcall Vector_set
xld.w %r6, Vector_Serial_interface_Ch_0_Receive_error
xld.w %r7, Serial_RxInterrupt
xcall Vector_set
xld.w %r6, Vector_Serial_interface_Ch_0_Transmit_buffer_empty
xld.w %r7, Serial_TxInterrupt
xcall Vector_set
ld.w %r5, 0
xld.w %r4, RxRead
ld.w [%r4], %r5
xld.w %r4, RxWrite
ld.w [%r4], %r5
xld.w %r4, TxRead
ld.w [%r4], %r5
xld.w %r4, TxWrite
ld.w [%r4], %r5
DISABLE_INTERRUPTS
xld.w %r4, R8_EFSIF_ADV ; set normal mode
ld.w %r5, 0
ld.b [%r4], %r5
xld.w %r4, R8_INT_FSIF01 ; clear the interrupt
xld.w %r5, FSTX0 | FSERR0 | FSRX0
ld.b [%r4], %r5
xld.w %r4, R8_INT_ESIF01
ld.b %r5, [%r4]
xand %r5, ~(ESRX0 | ESERR0 | ESTX0)
xoor %r5, ESRX0
ld.b [%r4], %r5
xld.w %r4, R8_INT_PLCDC_PSIO0
ld.ub %r5, [%r4]
xand %r5, 0x0f
xoor %r5, 0x70
ld.b [%r4], %r5
ENABLE_INTERRUPTS
ret
;;; receive all bytes from receive FIFO
;;; input:
;;; output:
.global Serial_RxInterrupt
Serial_RxInterrupt:
pushn %r14
Serial_RxInterrupt_1:
xld.w %r0, R8_INT_FSIF01 ; clear the interrupt
xld.w %r2, FSRX0 | FSERR0
ld.b [%r0], %r2
xld.w %r0, R8_EFSIF0_STATUS
xld.w %r1, R8_EFSIF0_RXD
xld.w %r2, RxRead
xld.w %r3, RxWrite
Serial_RxInterrupt_loop:
ld.ub %r4, [%r1] ; the received byte
ld.w %r5, [%r3] ; RxWrite
xld.w %r6, RxBuffer ; buffer start
add %r6, %r5 ; + offset
ld.b [%r6], %r4 ; store the byte
ld.w %r6, [%r2] ; RxRead
add %r5, 1 ; next position
xand %r5, (BufferSize - 1) ; mod buffer size
cmp %r6, %r5 ; read == write?
jreq Serial_RxInterrupt_no_store ; ...yes => buffer overrun, byte is lost
ld.w [%r3], %r5 ; update RxWrite
Serial_RxInterrupt_no_store:
ld.ub %r4, [%r0] ; read status
ld.w %r5, 0
ld.b [%r0], %r5 ; clear error flags
xand %r4, RDBFx
jrne Serial_RxInterrupt_loop
Serial_RxInterrupt_done:
popn %r14
reti
;;; not being used - errors are treated as normal characters
.if 0
;;; discard erroneous bytes from receive FIFO
;;; input:
;;; output:
.global Serial_RxErrorInterrupt
Serial_RxErrorInterrupt:
pushn %r14
xld.w %r0, R8_EFSIF0_STATUS
xld.w %r1, R8_EFSIF0_RXD
xld.w %r2, RxRead
xld.w %r3, RxWrite
Serial_RxErrorInterrupt_loop:
ld.ub %r4, [%r0]
xcall panic
ld.w %r5, 0
ld.b [%r0], %r5 ; clear error flags
xand %r4, RDBFx
jreq Serial_RxErrorInterrupt_done
ld.ub %r4, [%r1] ; the received byte
ld.w %r5, [%r3] ; RxWrite
xld.w %r6, RxBuffer ; buffer start
add %r6, %r5 ; + offset
ld.b [%r6], %r4 ; store the byte
ld.w %r6, [%r2] ; RxRead
add %r5, 1 ; next position
xand %r5, (BufferSize - 1) ; mod buffer size
cmp %r6, %r5 ; read == write?
jreq Serial_RxErrorInterrupt_loop ; ...yes => buffer overrun, byte is lost
ld.w [%r3], %r5 ; update RxWrite
jp Serial_RxErrorInterrupt_loop
Serial_RxErrorInterrupt_done:
xld.w %r0, R8_INT_FSIF01 ; clear the interrupt
xld.w %r2, FSERR0 | FSRX0
ld.b [%r0], %r2
popn %r14
reti
.endif
;;; send one byte
;;; input:
;;; output:
.global Serial_TxInterrupt
Serial_TxInterrupt:
pushn %r14
xld.w %r0, R8_INT_FSIF01
xld.w %r2, FSTX0
ld.b [%r0], %r2 ; clear Tx0 interrupt
xld.w %r0, TxRead
xld.w %r1, TxWrite
ld.w %r2, [%r0] ; read
ld.w %r1, [%r1] ; write
cmp %r1, %r2 ; read == write?
jreq Serial_TxInterrupt_buffer_empty ; ...yes => all sent
xld.w %r3, TxBuffer ; base address
add %r3, %r2
ld.ub %r4, [%r3] ; get the byte to send
add %r2, 1 ; increment offset
xand %r2, (BufferSize - 1) ; mod buffer size
ld.w [%r0], %r2 ; update offset
xld.w %r5, R8_EFSIF0_TXD ; transmit the byte
ld.b [%r5], %r4
cmp %r1, %r2 ; read == write?
jrne Serial_TxInterrupt_exit ; ...no => more to send
Serial_TxInterrupt_buffer_empty:
xld.w %r0, R8_INT_ESIF01
ld.b %r2, [%r0]
xand %r2, ~ESTX0
ld.b [%r0], %r2 ; disable Tx0 interrupt
Serial_TxInterrupt_exit:
xld.w %r0, R8_EFSIF0_STATUS ; check if pending receive
ld.ub %r4, [%r0]
xand %r4, RDBFx
jrne Serial_RxInterrupt_1 ; if pending receive
popn %r14
reti
Jump to Line
Something went wrong with that request. Please try again.