1 files changed, 191 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 000000000000..ef3f4c1df2a4
--- /dev/null
+++ b/arch/mn10300/kernel/mn10300-serial-low.S
@@ -0,0 +1,191 @@
+###############################################################################
+#
+# 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 <asm/proc/cache.h>
+#include <asm/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    0x01,(__tx_break,a3)    # handle transmit break request
+        bne     mnsc_vdma_tx_break
+
+        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     (__tx_info_buffer,a3),a2 # get the uart_info struct for Tx
+        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     +(GxICR_LEVEL_1|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_break:
+        movhu   (SCxCTR,e2),d2          # turn on break mode
+        or      SC01CTR_BKE,d2
+        movhu   d2,(SCxCTR,e2)
+        mov     +(GxICR_LEVEL_1|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