arch/mn10300/kernel/mn10300-serial-low.S

   1 ###############################################################################
   2 #
   3 # Virtual DMA driver for MN10300 serial ports
   4 #
   5 # Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
   6 # Written by David Howells (dhowells@redhat.com)
   7 #
   8 # This program is free software; you can redistribute it and/or
   9 # modify it under the terms of the GNU General Public Licence
  10 # as published by the Free Software Foundation; either version
  11 # 2 of the Licence, or (at your option) any later version.
  12 #
  13 ###############################################################################
  14 #include <linux/sys.h>
  15 #include <linux/linkage.h>
  16 #include <asm/page.h>
  17 #include <asm/smp.h>
  18 #include <asm/cpu-regs.h>
  19 #include <asm/frame.inc>
  20 #include <asm/timer-regs.h>
  21 #include <proc/cache.h>
  22 #include <unit/timex.h>
  23 #include "mn10300-serial.h"
  24
  25 #define SCxCTR  0x00
  26 #define SCxICR  0x04
  27 #define SCxTXB  0x08
  28 #define SCxRXB  0x09
  29 #define SCxSTR  0x0c
  30 #define SCxTIM  0x0d
  31
  32         .text
  33
  34 ###############################################################################
  35 #
  36 # serial port interrupt virtual DMA entry point
  37 # - intended to run at interrupt priority 1 (not affected by local_irq_disable)
  38 #
  39 ###############################################################################
  40         .balign L1_CACHE_BYTES
  41 ENTRY(mn10300_serial_vdma_interrupt)
  42 #       or      EPSW_IE,psw                     # permit overriding by
  43                                                 # debugging interrupts
  44         movm    [d2,d3,a2,a3,exreg0],(sp)
  45
  46         movhu   (IAGR),a2                       # see if which interrupt is
  47                                                 # pending
  48         and     IAGR_GN,a2
  49         add     a2,a2
  50         add     mn10300_serial_int_tbl,a2
  51
  52         mov     (a2+),a3
  53         mov     (__iobase,a3),e2
  54         mov     (a2),a2
  55         jmp     (a2)
  56
  57 ###############################################################################
  58 #
  59 # serial port receive interrupt virtual DMA entry point
  60 # - intended to run at interrupt priority 1 (not affected by local_irq_disable)
  61 # - stores data/status byte pairs in the ring buffer
  62 # - induces a scheduler tick timer interrupt when done, which we then subvert
  63 # on entry:
  64 #       A3      struct mn10300_serial_port *
  65 #       E2      I/O port base
  66 #
  67 ###############################################################################
  68 ENTRY(mn10300_serial_vdma_rx_handler)
  69         mov     (__rx_icr,a3),e3
  70         mov     GxICR_DETECT,d2
  71         movbu   d2,(e3)                         # ACK the interrupt
  72         movhu   (e3),d2                         # flush
  73
  74         mov     (__rx_inp,a3),d3
  75         mov     d3,a2
  76         add     2,d3
  77         and     MNSC_BUFFER_SIZE-1,d3
  78         mov     (__rx_outp,a3),d2
  79         cmp     d3,d2
  80         beq     mnsc_vdma_rx_overflow
  81
  82         mov     (__rx_buffer,a3),d2
  83         add     d2,a2
  84         movhu   (SCxSTR,e2),d2
  85         movbu   d2,(1,a2)
  86         movbu   (SCxRXB,e2),d2
  87         movbu   d2,(a2)
  88         mov     d3,(__rx_inp,a3)
  89         bset    MNSCx_RX_AVAIL,(__intr_flags,a3)
  90
  91 mnsc_vdma_rx_done:
  92         mov     (__tm_icr,a3),a2
  93         mov     GxICR_LEVEL_6|GxICR_ENABLE|GxICR_REQUEST|GxICR_DETECT,d2
  94         movhu   d2,(a2)                         # request a slow interrupt
  95         movhu   (a2),d2                         # flush
  96
  97         movm    (sp),[d2,d3,a2,a3,exreg0]
  98         rti
  99
 100 mnsc_vdma_rx_overflow:
 101         bset    MNSCx_RX_OVERF,(__intr_flags,a3)
 102         bra     mnsc_vdma_rx_done
 103
 104 ###############################################################################
 105 #
 106 # serial port transmit interrupt virtual DMA entry point
 107 # - intended to run at interrupt priority 1 (not affected by local_irq_disable)
 108 # - retrieves data bytes from the ring buffer and passes them to the serial port
 109 # - induces a scheduler tick timer interrupt when done, which we then subvert
 110 #       A3      struct mn10300_serial_port *
 111 #       E2      I/O port base
 112 #
 113 ###############################################################################
 114         .balign L1_CACHE_BYTES
 115 ENTRY(mn10300_serial_vdma_tx_handler)
 116         mov     (__tx_icr,a3),e3
 117         mov     GxICR_DETECT,d2
 118         movbu   d2,(e3)                 # ACK the interrupt
 119         movhu   (e3),d2                 # flush
 120
 121         btst    0xFF,(__tx_flags,a3)    # handle transmit flags
 122         bne     mnsc_vdma_tx_flags
 123
 124         movbu   (SCxSTR,e2),d2          # don't try and transmit a char if the
 125                                         # buffer is not empty
 126         btst    SC01STR_TBF,d2          # (may have tried to jumpstart)
 127         bne     mnsc_vdma_tx_noint
 128
 129         movbu   (__tx_xchar,a3),d2      # handle hi-pri XON/XOFF
 130         or      d2,d2
 131         bne     mnsc_vdma_tx_xchar
 132
 133         mov     (__uart_state,a3),a2    # see if the TTY Tx queue has anything in it
 134         mov     (__xmit_tail,a2),d3
 135         mov     (__xmit_head,a2),d2
 136         cmp     d3,d2
 137         beq     mnsc_vdma_tx_empty
 138
 139         mov     (__xmit_buffer,a2),d2   # get a char from the buffer and
 140                                         # transmit it
 141         movbu   (d3,d2),d2
 142         movbu   d2,(SCxTXB,e2)          # Tx
 143
 144         inc     d3                      # advance the buffer pointer
 145         and     __UART_XMIT_SIZE-1,d3
 146         mov     (__xmit_head,a2),d2
 147         mov     d3,(__xmit_tail,a2)
 148
 149         sub     d3,d2                   # see if we've written everything
 150         beq     mnsc_vdma_tx_empty
 151
 152         and     __UART_XMIT_SIZE-1,d2   # see if we just made a hole
 153         cmp     __UART_XMIT_SIZE-2,d2
 154         beq     mnsc_vdma_tx_made_hole
 155
 156 mnsc_vdma_tx_done:
 157         mov     (__tm_icr,a3),a2
 158         mov     GxICR_LEVEL_6|GxICR_ENABLE|GxICR_REQUEST|GxICR_DETECT,d2
 159         movhu   d2,(a2)                 # request a slow interrupt
 160         movhu   (a2),d2                 # flush
 161
 162 mnsc_vdma_tx_noint:
 163         movm    (sp),[d2,d3,a2,a3,exreg0]
 164         rti
 165
 166 mnsc_vdma_tx_empty:
 167         mov     +(NUM2GxICR_LEVEL(CONFIG_MN10300_SERIAL_IRQ_LEVEL)|GxICR_DETECT),d2
 168         movhu   d2,(e3)                 # disable the interrupt
 169         movhu   (e3),d2                 # flush
 170
 171         bset    MNSCx_TX_EMPTY,(__intr_flags,a3)
 172         bra     mnsc_vdma_tx_done
 173
 174 mnsc_vdma_tx_flags:
 175         btst    MNSCx_TX_STOP,(__tx_flags,a3)
 176         bne     mnsc_vdma_tx_stop
 177         movhu   (SCxCTR,e2),d2          # turn on break mode
 178         or      SC01CTR_BKE,d2
 179         movhu   d2,(SCxCTR,e2)
 180 mnsc_vdma_tx_stop:
 181         mov     +(NUM2GxICR_LEVEL(CONFIG_MN10300_SERIAL_IRQ_LEVEL)|GxICR_DETECT),d2
 182         movhu   d2,(e3)                 # disable transmit interrupts on this
 183                                         # channel
 184         movhu   (e3),d2                 # flush
 185         bra     mnsc_vdma_tx_noint
 186
 187 mnsc_vdma_tx_xchar:
 188         bclr    0xff,(__tx_xchar,a3)
 189         movbu   d2,(SCxTXB,e2)
 190         bra     mnsc_vdma_tx_done
 191
 192 mnsc_vdma_tx_made_hole:
 193         bset    MNSCx_TX_SPACE,(__intr_flags,a3)
 194         bra     mnsc_vdma_tx_done