############################################################################### # # 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