diff options
Diffstat (limited to 'arch/mn10300/kernel/mn10300-serial-low.S')
| -rw-r--r-- | arch/mn10300/kernel/mn10300-serial-low.S | 194 |
1 files changed, 194 insertions, 0 deletions
diff --git a/arch/mn10300/kernel/mn10300-serial-low.S b/arch/mn10300/kernel/mn10300-serial-low.S new file mode 100644 index 000000000..b95e76caf --- /dev/null +++ b/arch/mn10300/kernel/mn10300-serial-low.S @@ -0,0 +1,194 @@ +############################################################################### +# +# Virtual DMA driver for MN10300 serial ports +# +# Copyright (C) 2007 Red Hat, Inc. All Rights Reserved. +# Written by David Howells (dhowells@redhat.com) +# +# This program is free software; you can redistribute it and/or +# modify it under the terms of the GNU General Public Licence +# as published by the Free Software Foundation; either version +# 2 of the Licence, or (at your option) any later version. +# +############################################################################### +#include <linux/sys.h> +#include <linux/linkage.h> +#include <asm/page.h> +#include <asm/smp.h> +#include <asm/cpu-regs.h> +#include <asm/frame.inc> +#include <asm/timer-regs.h> +#include <proc/cache.h> +#include <unit/timex.h> +#include "mn10300-serial.h" + +#define SCxCTR 0x00 +#define SCxICR 0x04 +#define SCxTXB 0x08 +#define SCxRXB 0x09 +#define SCxSTR 0x0c +#define SCxTIM 0x0d + + .text + +############################################################################### +# +# serial port interrupt virtual DMA entry point +# - intended to run at interrupt priority 1 (not affected by local_irq_disable) +# +############################################################################### + .balign L1_CACHE_BYTES +ENTRY(mn10300_serial_vdma_interrupt) +# or EPSW_IE,psw # permit overriding by + # debugging interrupts + movm [d2,d3,a2,a3,exreg0],(sp) + + movhu (IAGR),a2 # see if which interrupt is + # pending + and IAGR_GN,a2 + add a2,a2 + add mn10300_serial_int_tbl,a2 + + mov (a2+),a3 + mov (__iobase,a3),e2 + mov (a2),a2 + jmp (a2) + +############################################################################### +# +# serial port receive interrupt virtual DMA entry point +# - intended to run at interrupt priority 1 (not affected by local_irq_disable) +# - stores data/status byte pairs in the ring buffer +# - induces a scheduler tick timer interrupt when done, which we then subvert +# on entry: +# A3 struct mn10300_serial_port * +# E2 I/O port base +# +############################################################################### +ENTRY(mn10300_serial_vdma_rx_handler) + mov (__rx_icr,a3),e3 + mov GxICR_DETECT,d2 + movbu d2,(e3) # ACK the interrupt + movhu (e3),d2 # flush + + mov (__rx_inp,a3),d3 + mov d3,a2 + add 2,d3 + and MNSC_BUFFER_SIZE-1,d3 + mov (__rx_outp,a3),d2 + cmp d3,d2 + beq mnsc_vdma_rx_overflow + + mov (__rx_buffer,a3),d2 + add d2,a2 + movhu (SCxSTR,e2),d2 + movbu d2,(1,a2) + movbu (SCxRXB,e2),d2 + movbu d2,(a2) + mov d3,(__rx_inp,a3) + bset MNSCx_RX_AVAIL,(__intr_flags,a3) + +mnsc_vdma_rx_done: + mov (__tm_icr,a3),a2 + mov GxICR_LEVEL_6|GxICR_ENABLE|GxICR_REQUEST|GxICR_DETECT,d2 + movhu d2,(a2) # request a slow interrupt + movhu (a2),d2 # flush + + movm (sp),[d2,d3,a2,a3,exreg0] + rti + +mnsc_vdma_rx_overflow: + bset MNSCx_RX_OVERF,(__intr_flags,a3) + bra mnsc_vdma_rx_done + +############################################################################### +# +# serial port transmit interrupt virtual DMA entry point +# - intended to run at interrupt priority 1 (not affected by local_irq_disable) +# - retrieves data bytes from the ring buffer and passes them to the serial port +# - induces a scheduler tick timer interrupt when done, which we then subvert +# A3 struct mn10300_serial_port * +# E2 I/O port base +# +############################################################################### + .balign L1_CACHE_BYTES +ENTRY(mn10300_serial_vdma_tx_handler) + mov (__tx_icr,a3),e3 + mov GxICR_DETECT,d2 + movbu d2,(e3) # ACK the interrupt + movhu (e3),d2 # flush + + btst 0xFF,(__tx_flags,a3) # handle transmit flags + bne mnsc_vdma_tx_flags + + movbu (SCxSTR,e2),d2 # don't try and transmit a char if the + # buffer is not empty + btst SC01STR_TBF,d2 # (may have tried to jumpstart) + bne mnsc_vdma_tx_noint + + movbu (__tx_xchar,a3),d2 # handle hi-pri XON/XOFF + or d2,d2 + bne mnsc_vdma_tx_xchar + + mov (__uart_state,a3),a2 # see if the TTY Tx queue has anything in it + mov (__xmit_tail,a2),d3 + mov (__xmit_head,a2),d2 + cmp d3,d2 + beq mnsc_vdma_tx_empty + + mov (__xmit_buffer,a2),d2 # get a char from the buffer and + # transmit it + movbu (d3,d2),d2 + movbu d2,(SCxTXB,e2) # Tx + + inc d3 # advance the buffer pointer + and __UART_XMIT_SIZE-1,d3 + mov (__xmit_head,a2),d2 + mov d3,(__xmit_tail,a2) + + sub d3,d2 # see if we've written everything + beq mnsc_vdma_tx_empty + + and __UART_XMIT_SIZE-1,d2 # see if we just made a hole + cmp __UART_XMIT_SIZE-2,d2 + beq mnsc_vdma_tx_made_hole + +mnsc_vdma_tx_done: + mov (__tm_icr,a3),a2 + mov GxICR_LEVEL_6|GxICR_ENABLE|GxICR_REQUEST|GxICR_DETECT,d2 + movhu d2,(a2) # request a slow interrupt + movhu (a2),d2 # flush + +mnsc_vdma_tx_noint: + movm (sp),[d2,d3,a2,a3,exreg0] + rti + +mnsc_vdma_tx_empty: + mov +(NUM2GxICR_LEVEL(CONFIG_MN10300_SERIAL_IRQ_LEVEL)|GxICR_DETECT),d2 + movhu d2,(e3) # disable the interrupt + movhu (e3),d2 # flush + + bset MNSCx_TX_EMPTY,(__intr_flags,a3) + bra mnsc_vdma_tx_done + +mnsc_vdma_tx_flags: + btst MNSCx_TX_STOP,(__tx_flags,a3) + bne mnsc_vdma_tx_stop + movhu (SCxCTR,e2),d2 # turn on break mode + or SC01CTR_BKE,d2 + movhu d2,(SCxCTR,e2) +mnsc_vdma_tx_stop: + mov +(NUM2GxICR_LEVEL(CONFIG_MN10300_SERIAL_IRQ_LEVEL)|GxICR_DETECT),d2 + movhu d2,(e3) # disable transmit interrupts on this + # channel + movhu (e3),d2 # flush + bra mnsc_vdma_tx_noint + +mnsc_vdma_tx_xchar: + bclr 0xff,(__tx_xchar,a3) + movbu d2,(SCxTXB,e2) + bra mnsc_vdma_tx_done + +mnsc_vdma_tx_made_hole: + bset MNSCx_TX_SPACE,(__intr_flags,a3) + bra mnsc_vdma_tx_done |