195 lines
5.3 KiB
ArmAsm
195 lines
5.3 KiB
ArmAsm
###############################################################################
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#
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# Virtual DMA driver for MN10300 serial ports
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#
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# Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
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# Written by David Howells (dhowells@redhat.com)
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#
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# This program is free software; you can redistribute it and/or
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# modify it under the terms of the GNU General Public Licence
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# as published by the Free Software Foundation; either version
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# 2 of the Licence, or (at your option) any later version.
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#
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###############################################################################
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#include <linux/sys.h>
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#include <linux/linkage.h>
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#include <asm/page.h>
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#include <asm/smp.h>
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#include <asm/cpu-regs.h>
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#include <asm/frame.inc>
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#include <asm/timer-regs.h>
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#include <proc/cache.h>
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#include <unit/timex.h>
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#include "mn10300-serial.h"
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#define SCxCTR 0x00
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#define SCxICR 0x04
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#define SCxTXB 0x08
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#define SCxRXB 0x09
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#define SCxSTR 0x0c
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#define SCxTIM 0x0d
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.text
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###############################################################################
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#
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# serial port interrupt virtual DMA entry point
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# - intended to run at interrupt priority 1 (not affected by local_irq_disable)
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#
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###############################################################################
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.balign L1_CACHE_BYTES
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ENTRY(mn10300_serial_vdma_interrupt)
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# or EPSW_IE,psw # permit overriding by
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# debugging interrupts
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movm [d2,d3,a2,a3,exreg0],(sp)
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movhu (IAGR),a2 # see if which interrupt is
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# pending
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and IAGR_GN,a2
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add a2,a2
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add mn10300_serial_int_tbl,a2
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mov (a2+),a3
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mov (__iobase,a3),e2
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mov (a2),a2
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jmp (a2)
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###############################################################################
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#
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# serial port receive interrupt virtual DMA entry point
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# - intended to run at interrupt priority 1 (not affected by local_irq_disable)
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# - stores data/status byte pairs in the ring buffer
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# - induces a scheduler tick timer interrupt when done, which we then subvert
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# on entry:
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# A3 struct mn10300_serial_port *
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# E2 I/O port base
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#
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###############################################################################
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ENTRY(mn10300_serial_vdma_rx_handler)
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mov (__rx_icr,a3),e3
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mov GxICR_DETECT,d2
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movbu d2,(e3) # ACK the interrupt
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movhu (e3),d2 # flush
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mov (__rx_inp,a3),d3
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mov d3,a2
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add 2,d3
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and MNSC_BUFFER_SIZE-1,d3
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mov (__rx_outp,a3),d2
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cmp d3,d2
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beq mnsc_vdma_rx_overflow
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mov (__rx_buffer,a3),d2
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add d2,a2
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movhu (SCxSTR,e2),d2
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movbu d2,(1,a2)
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movbu (SCxRXB,e2),d2
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movbu d2,(a2)
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mov d3,(__rx_inp,a3)
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bset MNSCx_RX_AVAIL,(__intr_flags,a3)
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mnsc_vdma_rx_done:
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mov (__tm_icr,a3),a2
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mov GxICR_LEVEL_6|GxICR_ENABLE|GxICR_REQUEST|GxICR_DETECT,d2
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movhu d2,(a2) # request a slow interrupt
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movhu (a2),d2 # flush
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movm (sp),[d2,d3,a2,a3,exreg0]
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rti
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mnsc_vdma_rx_overflow:
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bset MNSCx_RX_OVERF,(__intr_flags,a3)
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bra mnsc_vdma_rx_done
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###############################################################################
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#
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# serial port transmit interrupt virtual DMA entry point
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# - intended to run at interrupt priority 1 (not affected by local_irq_disable)
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# - retrieves data bytes from the ring buffer and passes them to the serial port
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# - induces a scheduler tick timer interrupt when done, which we then subvert
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# A3 struct mn10300_serial_port *
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# E2 I/O port base
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#
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###############################################################################
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.balign L1_CACHE_BYTES
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ENTRY(mn10300_serial_vdma_tx_handler)
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mov (__tx_icr,a3),e3
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mov GxICR_DETECT,d2
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movbu d2,(e3) # ACK the interrupt
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movhu (e3),d2 # flush
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btst 0xFF,(__tx_flags,a3) # handle transmit flags
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bne mnsc_vdma_tx_flags
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movbu (SCxSTR,e2),d2 # don't try and transmit a char if the
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# buffer is not empty
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btst SC01STR_TBF,d2 # (may have tried to jumpstart)
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bne mnsc_vdma_tx_noint
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movbu (__tx_xchar,a3),d2 # handle hi-pri XON/XOFF
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or d2,d2
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bne mnsc_vdma_tx_xchar
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mov (__uart_state,a3),a2 # see if the TTY Tx queue has anything in it
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mov (__xmit_tail,a2),d3
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mov (__xmit_head,a2),d2
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cmp d3,d2
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beq mnsc_vdma_tx_empty
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mov (__xmit_buffer,a2),d2 # get a char from the buffer and
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# transmit it
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movbu (d3,d2),d2
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movbu d2,(SCxTXB,e2) # Tx
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inc d3 # advance the buffer pointer
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and __UART_XMIT_SIZE-1,d3
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mov (__xmit_head,a2),d2
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mov d3,(__xmit_tail,a2)
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sub d3,d2 # see if we've written everything
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beq mnsc_vdma_tx_empty
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and __UART_XMIT_SIZE-1,d2 # see if we just made a hole
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cmp __UART_XMIT_SIZE-2,d2
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beq mnsc_vdma_tx_made_hole
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mnsc_vdma_tx_done:
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mov (__tm_icr,a3),a2
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mov GxICR_LEVEL_6|GxICR_ENABLE|GxICR_REQUEST|GxICR_DETECT,d2
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movhu d2,(a2) # request a slow interrupt
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movhu (a2),d2 # flush
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mnsc_vdma_tx_noint:
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movm (sp),[d2,d3,a2,a3,exreg0]
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rti
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mnsc_vdma_tx_empty:
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mov +(NUM2GxICR_LEVEL(CONFIG_MN10300_SERIAL_IRQ_LEVEL)|GxICR_DETECT),d2
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movhu d2,(e3) # disable the interrupt
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movhu (e3),d2 # flush
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bset MNSCx_TX_EMPTY,(__intr_flags,a3)
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bra mnsc_vdma_tx_done
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mnsc_vdma_tx_flags:
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btst MNSCx_TX_STOP,(__tx_flags,a3)
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bne mnsc_vdma_tx_stop
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movhu (SCxCTR,e2),d2 # turn on break mode
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or SC01CTR_BKE,d2
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movhu d2,(SCxCTR,e2)
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mnsc_vdma_tx_stop:
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mov +(NUM2GxICR_LEVEL(CONFIG_MN10300_SERIAL_IRQ_LEVEL)|GxICR_DETECT),d2
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movhu d2,(e3) # disable transmit interrupts on this
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# channel
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movhu (e3),d2 # flush
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bra mnsc_vdma_tx_noint
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mnsc_vdma_tx_xchar:
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bclr 0xff,(__tx_xchar,a3)
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movbu d2,(SCxTXB,e2)
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bra mnsc_vdma_tx_done
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mnsc_vdma_tx_made_hole:
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bset MNSCx_TX_SPACE,(__intr_flags,a3)
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bra mnsc_vdma_tx_done
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