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 41ENTRY(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############################################################################### 68ENTRY(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 91mnsc_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 100mnsc_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 115ENTRY(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 0x01,(__tx_break,a3) # handle transmit break request 122 bne mnsc_vdma_tx_break 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 156mnsc_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 162mnsc_vdma_tx_noint: 163 movm (sp),[d2,d3,a2,a3,exreg0] 164 rti 165 166mnsc_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 174mnsc_vdma_tx_break: 175 movhu (SCxCTR,e2),d2 # turn on break mode 176 or SC01CTR_BKE,d2 177 movhu d2,(SCxCTR,e2) 178 mov +(NUM2GxICR_LEVEL(CONFIG_MN10300_SERIAL_IRQ_LEVEL)|GxICR_DETECT),d2 179 movhu d2,(e3) # disable transmit interrupts on this 180 # channel 181 movhu (e3),d2 # flush 182 bra mnsc_vdma_tx_noint 183 184mnsc_vdma_tx_xchar: 185 bclr 0xff,(__tx_xchar,a3) 186 movbu d2,(SCxTXB,e2) 187 bra mnsc_vdma_tx_done 188 189mnsc_vdma_tx_made_hole: 190 bset MNSCx_TX_SPACE,(__intr_flags,a3) 191 bra mnsc_vdma_tx_done 192