8f0bcbcab0
The SoC serial port driver uses a high priority interrupt to handle tx of characters in the tx ring buffer. The driver needs to disable/enable this IRQ from outside of irq context. The original code to do this is not foolproof on SMP machines because the IRQ running on one core could still access the serial port for a short time after the driver running on another core disables the interrupt. This patch adds a flag to tell the IRQ handler that the driver wants to disable the interrupt. After seeing the flag, the IRQ handler will immediately disable the interrupt and exit. After setting the flag, the driver will wait for interrupt to be disabled by the IRQ handler. Signed-off-by: Mark Salter <msalter@redhat.com> Signed-off-by: David Howells <dhowells@redhat.com>
195 lines
5.3 KiB
ArmAsm
195 lines
5.3 KiB
ArmAsm
###############################################################################
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#
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# Virtual DMA driver for MN10300 serial ports
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#
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# Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
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# Written by David Howells (dhowells@redhat.com)
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#
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# This program is free software; you can redistribute it and/or
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# modify it under the terms of the GNU General Public Licence
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# as published by the Free Software Foundation; either version
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# 2 of the Licence, or (at your option) any later version.
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#
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###############################################################################
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#include <linux/sys.h>
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#include <linux/linkage.h>
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#include <asm/page.h>
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#include <asm/smp.h>
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#include <asm/cpu-regs.h>
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#include <asm/frame.inc>
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#include <asm/timer-regs.h>
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#include <proc/cache.h>
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#include <unit/timex.h>
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#include "mn10300-serial.h"
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#define SCxCTR 0x00
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#define SCxICR 0x04
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#define SCxTXB 0x08
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#define SCxRXB 0x09
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#define SCxSTR 0x0c
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#define SCxTIM 0x0d
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.text
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###############################################################################
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#
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# serial port interrupt virtual DMA entry point
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# - intended to run at interrupt priority 1 (not affected by local_irq_disable)
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#
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###############################################################################
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.balign L1_CACHE_BYTES
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ENTRY(mn10300_serial_vdma_interrupt)
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# or EPSW_IE,psw # permit overriding by
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# debugging interrupts
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movm [d2,d3,a2,a3,exreg0],(sp)
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movhu (IAGR),a2 # see if which interrupt is
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# pending
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and IAGR_GN,a2
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add a2,a2
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add mn10300_serial_int_tbl,a2
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mov (a2+),a3
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mov (__iobase,a3),e2
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mov (a2),a2
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jmp (a2)
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###############################################################################
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#
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# serial port receive interrupt virtual DMA entry point
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# - intended to run at interrupt priority 1 (not affected by local_irq_disable)
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# - stores data/status byte pairs in the ring buffer
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# - induces a scheduler tick timer interrupt when done, which we then subvert
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# on entry:
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# A3 struct mn10300_serial_port *
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# E2 I/O port base
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#
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###############################################################################
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ENTRY(mn10300_serial_vdma_rx_handler)
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mov (__rx_icr,a3),e3
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mov GxICR_DETECT,d2
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movbu d2,(e3) # ACK the interrupt
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movhu (e3),d2 # flush
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mov (__rx_inp,a3),d3
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mov d3,a2
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add 2,d3
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and MNSC_BUFFER_SIZE-1,d3
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mov (__rx_outp,a3),d2
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cmp d3,d2
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beq mnsc_vdma_rx_overflow
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mov (__rx_buffer,a3),d2
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add d2,a2
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movhu (SCxSTR,e2),d2
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movbu d2,(1,a2)
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movbu (SCxRXB,e2),d2
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movbu d2,(a2)
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mov d3,(__rx_inp,a3)
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bset MNSCx_RX_AVAIL,(__intr_flags,a3)
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mnsc_vdma_rx_done:
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mov (__tm_icr,a3),a2
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mov GxICR_LEVEL_6|GxICR_ENABLE|GxICR_REQUEST|GxICR_DETECT,d2
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movhu d2,(a2) # request a slow interrupt
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movhu (a2),d2 # flush
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movm (sp),[d2,d3,a2,a3,exreg0]
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rti
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mnsc_vdma_rx_overflow:
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bset MNSCx_RX_OVERF,(__intr_flags,a3)
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bra mnsc_vdma_rx_done
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###############################################################################
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#
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# serial port transmit interrupt virtual DMA entry point
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# - intended to run at interrupt priority 1 (not affected by local_irq_disable)
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# - retrieves data bytes from the ring buffer and passes them to the serial port
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# - induces a scheduler tick timer interrupt when done, which we then subvert
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# A3 struct mn10300_serial_port *
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# E2 I/O port base
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#
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###############################################################################
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.balign L1_CACHE_BYTES
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ENTRY(mn10300_serial_vdma_tx_handler)
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mov (__tx_icr,a3),e3
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mov GxICR_DETECT,d2
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movbu d2,(e3) # ACK the interrupt
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movhu (e3),d2 # flush
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btst 0xFF,(__tx_flags,a3) # handle transmit flags
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bne mnsc_vdma_tx_flags
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movbu (SCxSTR,e2),d2 # don't try and transmit a char if the
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# buffer is not empty
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btst SC01STR_TBF,d2 # (may have tried to jumpstart)
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bne mnsc_vdma_tx_noint
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movbu (__tx_xchar,a3),d2 # handle hi-pri XON/XOFF
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or d2,d2
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bne mnsc_vdma_tx_xchar
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mov (__uart_state,a3),a2 # see if the TTY Tx queue has anything in it
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mov (__xmit_tail,a2),d3
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mov (__xmit_head,a2),d2
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cmp d3,d2
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beq mnsc_vdma_tx_empty
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mov (__xmit_buffer,a2),d2 # get a char from the buffer and
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# transmit it
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movbu (d3,d2),d2
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movbu d2,(SCxTXB,e2) # Tx
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inc d3 # advance the buffer pointer
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and __UART_XMIT_SIZE-1,d3
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mov (__xmit_head,a2),d2
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mov d3,(__xmit_tail,a2)
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sub d3,d2 # see if we've written everything
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beq mnsc_vdma_tx_empty
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and __UART_XMIT_SIZE-1,d2 # see if we just made a hole
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cmp __UART_XMIT_SIZE-2,d2
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beq mnsc_vdma_tx_made_hole
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mnsc_vdma_tx_done:
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mov (__tm_icr,a3),a2
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mov GxICR_LEVEL_6|GxICR_ENABLE|GxICR_REQUEST|GxICR_DETECT,d2
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movhu d2,(a2) # request a slow interrupt
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movhu (a2),d2 # flush
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mnsc_vdma_tx_noint:
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movm (sp),[d2,d3,a2,a3,exreg0]
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rti
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mnsc_vdma_tx_empty:
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mov +(NUM2GxICR_LEVEL(CONFIG_MN10300_SERIAL_IRQ_LEVEL)|GxICR_DETECT),d2
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movhu d2,(e3) # disable the interrupt
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movhu (e3),d2 # flush
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bset MNSCx_TX_EMPTY,(__intr_flags,a3)
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bra mnsc_vdma_tx_done
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mnsc_vdma_tx_flags:
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btst MNSCx_TX_STOP,(__tx_flags,a3)
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bne mnsc_vdma_tx_stop
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movhu (SCxCTR,e2),d2 # turn on break mode
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or SC01CTR_BKE,d2
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movhu d2,(SCxCTR,e2)
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mnsc_vdma_tx_stop:
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mov +(NUM2GxICR_LEVEL(CONFIG_MN10300_SERIAL_IRQ_LEVEL)|GxICR_DETECT),d2
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movhu d2,(e3) # disable transmit interrupts on this
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# channel
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movhu (e3),d2 # flush
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bra mnsc_vdma_tx_noint
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mnsc_vdma_tx_xchar:
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bclr 0xff,(__tx_xchar,a3)
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movbu d2,(SCxTXB,e2)
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bra mnsc_vdma_tx_done
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mnsc_vdma_tx_made_hole:
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bset MNSCx_TX_SPACE,(__intr_flags,a3)
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bra mnsc_vdma_tx_done
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