diff options
Diffstat (limited to 'arch/mips/mips-boards/sim/sim_IRQ.c')
| -rw-r--r-- | arch/mips/mips-boards/sim/sim_IRQ.c | 148 |
1 files changed, 148 insertions, 0 deletions
diff --git a/arch/mips/mips-boards/sim/sim_IRQ.c b/arch/mips/mips-boards/sim/sim_IRQ.c new file mode 100644 index 00000000000..9987a85aabe --- /dev/null +++ b/arch/mips/mips-boards/sim/sim_IRQ.c @@ -0,0 +1,148 @@ +/* + * Carsten Langgaard, carstenl@mips.com + * Copyright (C) 1999, 2000 MIPS Technologies, Inc. All rights reserved. + * + * This program is free software; you can distribute it and/or modify it + * under the terms of the GNU General Public License (Version 2) as + * published by the Free Software Foundation. + * + * This program is distributed in the hope it will be useful, but WITHOUT + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or + * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License + * for more details. + * + * You should have received a copy of the GNU General Public License along + * with this program; if not, write to the Free Software Foundation, Inc., + * 59 Temple Place - Suite 330, Boston MA 02111-1307, USA. + * + * Interrupt exception dispatch code. + */ +#include <linux/config.h> + +#include <asm/asm.h> +#include <asm/mipsregs.h> +#include <asm/regdef.h> +#include <asm/stackframe.h> + +/* A lot of complication here is taken away because: + * + * 1) We handle one interrupt and return, sitting in a loop and moving across + * all the pending IRQ bits in the cause register is _NOT_ the answer, the + * common case is one pending IRQ so optimize in that direction. + * + * 2) We need not check against bits in the status register IRQ mask, that + * would make this routine slow as hell. + * + * 3) Linux only thinks in terms of all IRQs on or all IRQs off, nothing in + * between like BSD spl() brain-damage. + * + * Furthermore, the IRQs on the MIPS board look basically (barring software + * IRQs which we don't use at all and all external interrupt sources are + * combined together on hardware interrupt 0 (MIPS IRQ 2)) like: + * + * MIPS IRQ Source + * -------- ------ + * 0 Software (ignored) + * 1 Software (ignored) + * 2 Combined hardware interrupt (hw0) + * 3 Hardware (ignored) + * 4 Hardware (ignored) + * 5 Hardware (ignored) + * 6 Hardware (ignored) + * 7 R4k timer (what we use) + * + * Note: On the SEAD board thing are a little bit different. + * Here IRQ 2 (hw0) is wired to the UART0 and IRQ 3 (hw1) is wired + * wired to UART1. + * + * We handle the IRQ according to _our_ priority which is: + * + * Highest ---- R4k Timer + * Lowest ---- Combined hardware interrupt + * + * then we just return, if multiple IRQs are pending then we will just take + * another exception, big deal. + */ + + .text + .set noreorder + .set noat + .align 5 + NESTED(mipsIRQ, PT_SIZE, sp) + SAVE_ALL + CLI + .set at + + mfc0 s0, CP0_CAUSE # get irq bits + mfc0 s1, CP0_STATUS # get irq mask + and s0, s1 + + /* First we check for r4k counter/timer IRQ. */ + andi a0, s0, CAUSEF_IP7 + beq a0, zero, 1f + andi a0, s0, CAUSEF_IP2 # delay slot, check hw0 interrupt + + /* Wheee, a timer interrupt. */ + move a0, sp + jal mips_timer_interrupt + nop + + j ret_from_irq + nop + +1: +#if defined(CONFIG_MIPS_SEAD) + beq a0, zero, 1f + andi a0, s0, CAUSEF_IP3 # delay slot, check hw1 interrupt +#else + beq a0, zero, 1f # delay slot, check hw3 interrupt + andi a0, s0, CAUSEF_IP5 +#endif + + /* Wheee, combined hardware level zero interrupt. */ +#if defined(CONFIG_MIPS_ATLAS) + jal atlas_hw0_irqdispatch +#elif defined(CONFIG_MIPS_MALTA) + jal malta_hw0_irqdispatch +#elif defined(CONFIG_MIPS_SEAD) + jal sead_hw0_irqdispatch +#else +#error "MIPS board not supported\n" +#endif + move a0, sp # delay slot + + j ret_from_irq + nop # delay slot + +1: +#if defined(CONFIG_MIPS_SEAD) + beq a0, zero, 1f + andi a0, s0, CAUSEF_IP5 # delay slot, check hw3 interrupt + jal sead_hw1_irqdispatch + move a0, sp # delay slot + j ret_from_irq + nop # delay slot +1: +#endif +#if defined(CONFIG_MIPS_MALTA) + beq a0, zero, 1f # check hw3 (coreHI) interrupt + nop + jal corehi_irqdispatch + move a0, sp + j ret_from_irq + nop +1: +#endif + /* + * Here by mistake? This is possible, what can happen is that by the + * time we take the exception the IRQ pin goes low, so just leave if + * this is the case. + */ + move a1,s0 + PRINT("Got interrupt: c0_cause = %08x\n") + mfc0 a1, CP0_EPC + PRINT("c0_epc = %08x\n") + + j ret_from_irq + nop + END(mipsIRQ) |