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xtensa: dispatch medium-priority interrupts 

Add support for dispatching medium-priority interrupts, that is,
interrupts of priority levels 2 to EXCM_LEVEL. IRQ handling may be
preempted by higher priority IRQ.

Signed-off-by: Marc Gauthier <marc@tensilica.com>
Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
Signed-off-by: Chris Zankel <chris@zankel.net>
This commit is contained in:
Marc Gauthier 2013-01-05 04:57:17 +04:00 committed by Chris Zankel
parent d0b73b488c
commit 2d1c645cc5
10 changed files with 261 additions and 46 deletions
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6
arch/xtensa/include/asm/atomic.h
View File

@ -7,7 +7,7 @@
* License. See the file "COPYING" in the main directory of this archive
* for more details.
*
* Copyright (C) 2001 - 2005 Tensilica Inc.
* Copyright (C) 2001 - 2008 Tensilica Inc.
*/
#ifndef _XTENSA_ATOMIC_H
@ -24,11 +24,11 @@
/*
* This Xtensa implementation assumes that the right mechanism
* for exclusion is for locking interrupts to level 1.
* for exclusion is for locking interrupts to level EXCM_LEVEL.
*
* Locking interrupts looks like this:
*
* rsil a15, 1
* rsil a15, LOCKLEVEL
* <code>
* wsr a15, PS
* rsync

4
arch/xtensa/include/asm/processor.h
View File

@ -5,7 +5,7 @@
* License. See the file "COPYING" in the main directory of this archive
* for more details.
*
* Copyright (C) 2001 - 2005 Tensilica Inc.
* Copyright (C) 2001 - 2008 Tensilica Inc.
*/
#ifndef _XTENSA_PROCESSOR_H
@ -68,7 +68,7 @@
/* LOCKLEVEL defines the interrupt level that masks all
* general-purpose interrupts.
*/
#define LOCKLEVEL 1
#define LOCKLEVEL XCHAL_EXCM_LEVEL
/* WSBITS and WBBITS are the width of the WINDOWSTART and WINDOWBASE
* registers

1
arch/xtensa/include/asm/regs.h
View File

@ -88,6 +88,7 @@
#define PS_UM_BIT 5
#define PS_EXCM_BIT 4
#define PS_INTLEVEL_SHIFT 0
#define PS_INTLEVEL_WIDTH 4
#define PS_INTLEVEL_MASK 0x0000000F
/* DBREAKCn register fields. */

8
arch/xtensa/include/asm/timex.h
View File

@ -5,7 +5,7 @@
* License. See the file "COPYING" in the main directory of this archive
* for more details.
*
* Copyright (C) 2001 - 2005 Tensilica Inc.
* Copyright (C) 2001 - 2008 Tensilica Inc.
*/
#ifndef _XTENSA_TIMEX_H
@ -19,13 +19,13 @@
#define _INTLEVEL(x) XCHAL_INT ## x ## _LEVEL
#define INTLEVEL(x) _INTLEVEL(x)
#if INTLEVEL(XCHAL_TIMER0_INTERRUPT) == 1
#if INTLEVEL(XCHAL_TIMER0_INTERRUPT) <= XCHAL_EXCM_LEVEL
# define LINUX_TIMER 0
# define LINUX_TIMER_INT XCHAL_TIMER0_INTERRUPT
#elif INTLEVEL(XCHAL_TIMER1_INTERRUPT) == 1
#elif INTLEVEL(XCHAL_TIMER1_INTERRUPT) <= XCHAL_EXCM_LEVEL
# define LINUX_TIMER 1
# define LINUX_TIMER_INT XCHAL_TIMER1_INTERRUPT
#elif INTLEVEL(XCHAL_TIMER2_INTERRUPT) == 1
#elif INTLEVEL(XCHAL_TIMER2_INTERRUPT) <= XCHAL_EXCM_LEVEL
# define LINUX_TIMER 2
# define LINUX_TIMER_INT XCHAL_TIMER2_INTERRUPT
#else

59
arch/xtensa/kernel/entry.S
View File

@ -7,7 +7,7 @@
* License. See the file "COPYING" in the main directory of this archive
* for more details.
*
* Copyright (C) 2004-2007 by Tensilica Inc.
* Copyright (C) 2004 - 2008 by Tensilica Inc.
*
* Chris Zankel <chris@zankel.net>
*
@ -349,15 +349,16 @@ common_exception:
* so we can allow exceptions and interrupts (*) again.
* Set PS(EXCM = 0, UM = 0, RING = 0, OWB = 0, WOE = 1, INTLEVEL = X)
*
* (*) We only allow interrupts if PS.INTLEVEL was not set to 1 before
* (interrupts disabled) and if this exception is not an interrupt.
* (*) We only allow interrupts of higher priority than current IRQ
*/
rsr a3, ps
addi a0, a0, -4
movi a2, 1
extui a3, a3, 0, 1 # a3 = PS.INTLEVEL[0]
moveqz a3, a2, a0 # a3 = 1 iff interrupt exception
extui a3, a3, PS_INTLEVEL_SHIFT, PS_INTLEVEL_WIDTH
# a3 = PS.INTLEVEL
movnez a2, a3, a3 # a2 = 1: level-1, > 1: high priority
moveqz a3, a2, a0 # a3 = IRQ level iff interrupt
movi a2, 1 << PS_WOE_BIT
or a3, a3, a2
rsr a0, exccause
@ -641,19 +642,51 @@ common_exception_exit:
l32i a0, a1, PT_DEPC
l32i a3, a1, PT_AREG3
l32i a2, a1, PT_AREG2
_bgeui a0, VALID_DOUBLE_EXCEPTION_ADDRESS, 1f
_bltui a0, VALID_DOUBLE_EXCEPTION_ADDRESS, 1f
wsr a0, depc
l32i a2, a1, PT_AREG2
l32i a0, a1, PT_AREG0
l32i a1, a1, PT_AREG1
rfde
1:
/* Restore a0...a3 and return */
rsr a0, ps
extui a2, a0, PS_INTLEVEL_SHIFT, PS_INTLEVEL_WIDTH
movi a0, 2f
slli a2, a2, 4
add a0, a2, a0
l32i a2, a1, PT_AREG2
jx a0
.macro irq_exit_level level
.align 16
.if XCHAL_EXCM_LEVEL >= \level
l32i a0, a1, PT_PC
wsr a0, epc\level
l32i a0, a1, PT_AREG0
l32i a1, a1, PT_AREG1
rfi \level
.endif
.endm
.align 16
2:
l32i a0, a1, PT_AREG0
l32i a1, a1, PT_AREG1
rfe
1: wsr a0, depc
l32i a0, a1, PT_AREG0
l32i a1, a1, PT_AREG1
rfde
.align 16
/* no rfi for level-1 irq, handled by rfe above*/
nop
irq_exit_level 2
irq_exit_level 3
irq_exit_level 4
irq_exit_level 5
irq_exit_level 6
ENDPROC(kernel_exception)
@ -753,7 +786,7 @@ ENTRY(unrecoverable_exception)
wsr a1, windowbase
rsync
movi a1, (1 << PS_WOE_BIT) | 1
movi a1, (1 << PS_WOE_BIT) | LOCKLEVEL
wsr a1, ps
rsync
@ -1474,7 +1507,7 @@ ENTRY(_spill_registers)
l32i a1, a3, EXC_TABLE_KSTK
wsr a3, excsave1
movi a4, (1 << PS_WOE_BIT) | 1
movi a4, (1 << PS_WOE_BIT) | LOCKLEVEL
wsr a4, ps
rsync

9
arch/xtensa/kernel/head.S
View File

@ -7,7 +7,7 @@
* License. See the file "COPYING" in the main directory of this archive
* for more details.
*
* Copyright (C) 2001 - 2005 Tensilica Inc.
* Copyright (C) 2001 - 2008 Tensilica Inc.
*
* Chris Zankel <chris@zankel.net>
* Marc Gauthier <marc@tensilica.com, marc@alumni.uwaterloo.ca>
@ -128,14 +128,14 @@ ENTRY(_startup)
wsr a0, cpenable
#endif
/* Set PS.INTLEVEL=1, PS.WOE=0, kernel stack, PS.EXCM=0
/* Set PS.INTLEVEL=LOCKLEVEL, PS.WOE=0, kernel stack, PS.EXCM=0
*
* Note: PS.EXCM must be cleared before using any loop
* instructions; otherwise, they are silently disabled, and
* at most one iteration of the loop is executed.
*/
movi a1, 1
movi a1, LOCKLEVEL
wsr a1, ps
rsync
@ -211,7 +211,8 @@ ENTRY(_startup)
movi a1, init_thread_union
addi a1, a1, KERNEL_STACK_SIZE
movi a2, 0x00040001 # WOE=1, INTLEVEL=1, UM=0
movi a2, (1 << PS_WOE_BIT) | LOCKLEVEL
# WOE=1, INTLEVEL=LOCKLEVEL, UM=0
wsr a2, ps # (enable reg-windows; progmode stack)
rsync

42
arch/xtensa/kernel/setup.c
View File

@ -328,6 +328,27 @@ extern char _UserExceptionVector_literal_start;
extern char _UserExceptionVector_text_end;
extern char _DoubleExceptionVector_literal_start;
extern char _DoubleExceptionVector_text_end;
#if XCHAL_EXCM_LEVEL >= 2
extern char _Level2InterruptVector_text_start;
extern char _Level2InterruptVector_text_end;
#endif
#if XCHAL_EXCM_LEVEL >= 3
extern char _Level3InterruptVector_text_start;
extern char _Level3InterruptVector_text_end;
#endif
#if XCHAL_EXCM_LEVEL >= 4
extern char _Level4InterruptVector_text_start;
extern char _Level4InterruptVector_text_end;
#endif
#if XCHAL_EXCM_LEVEL >= 5
extern char _Level5InterruptVector_text_start;
extern char _Level5InterruptVector_text_end;
#endif
#if XCHAL_EXCM_LEVEL >= 6
extern char _Level6InterruptVector_text_start;
extern char _Level6InterruptVector_text_end;
#endif
#ifdef CONFIG_S32C1I_SELFTEST
@ -482,6 +503,27 @@ void __init setup_arch(char **cmdline_p)
mem_reserve(__pa(&_DoubleExceptionVector_literal_start),
__pa(&_DoubleExceptionVector_text_end), 0);
#if XCHAL_EXCM_LEVEL >= 2
mem_reserve(__pa(&_Level2InterruptVector_text_start),
__pa(&_Level2InterruptVector_text_end), 0);
#endif
#if XCHAL_EXCM_LEVEL >= 3
mem_reserve(__pa(&_Level3InterruptVector_text_start),
__pa(&_Level3InterruptVector_text_end), 0);
#endif
#if XCHAL_EXCM_LEVEL >= 4
mem_reserve(__pa(&_Level4InterruptVector_text_start),
__pa(&_Level4InterruptVector_text_end), 0);
#endif
#if XCHAL_EXCM_LEVEL >= 5
mem_reserve(__pa(&_Level5InterruptVector_text_start),
__pa(&_Level5InterruptVector_text_end), 0);
#endif
#if XCHAL_EXCM_LEVEL >= 6
mem_reserve(__pa(&_Level6InterruptVector_text_start),
__pa(&_Level6InterruptVector_text_end), 0);
#endif
bootmem_init();
#ifdef CONFIG_OF

45
arch/xtensa/kernel/traps.c
View File

@ -193,26 +193,47 @@ void do_multihit(struct pt_regs *regs, unsigned long exccause)
}
/*
* Level-1 interrupt.
* We currently have no priority encoding.
* IRQ handler.
* PS.INTLEVEL is the current IRQ priority level.
*/
unsigned long ignored_level1_interrupts;
extern void do_IRQ(int, struct pt_regs *);
void do_interrupt(struct pt_regs *regs)
{
unsigned long intread = get_sr (interrupt);
unsigned long intenable = get_sr (intenable);
int i, mask;
static const unsigned int_level_mask[] = {
0,
XCHAL_INTLEVEL1_MASK,
XCHAL_INTLEVEL2_MASK,
XCHAL_INTLEVEL3_MASK,
XCHAL_INTLEVEL4_MASK,
XCHAL_INTLEVEL5_MASK,
XCHAL_INTLEVEL6_MASK,
XCHAL_INTLEVEL7_MASK,
};
unsigned level = get_sr(ps) & PS_INTLEVEL_MASK;
/* Handle all interrupts (no priorities).
* (Clear the interrupt before processing, in case it's
* edge-triggered or software-generated)
if (WARN_ON_ONCE(level >= ARRAY_SIZE(int_level_mask)))
return;
for (;;) {
unsigned intread = get_sr(interrupt);
unsigned intenable = get_sr(intenable);
unsigned int_at_level = intread & intenable &
int_level_mask[level];
if (!int_at_level)
return;
/*
* Clear the interrupt before processing, in case it's
* edge-triggered or software-generated
*/
while (int_at_level) {
unsigned i = __ffs(int_at_level);
unsigned mask = 1 << i;
for (i=0, mask = 1; i < XCHAL_NUM_INTERRUPTS; i++, mask <<= 1) {
if (mask & (intread & intenable)) {
int_at_level ^= mask;
set_sr(mask, intclear);
do_IRQ(i, regs);
}
@ -397,7 +418,7 @@ static inline void spill_registers(void)
unsigned int a0, ps;
__asm__ __volatile__ (
"movi a14, " __stringify(PS_EXCM_BIT | 1) "\n\t"
"movi a14, " __stringify(PS_EXCM_BIT | LOCKLEVEL) "\n\t"
"mov a12, a0\n\t"
"rsr a13, sar\n\t"
"xsr a14, ps\n\t"

57
arch/xtensa/kernel/vectors.S
View File

@ -10,7 +10,7 @@
* Public License. See the file "COPYING" in the main directory of
* this archive for more details.
*
* Copyright (C) 2005 Tensilica, Inc.
* Copyright (C) 2005 - 2008 Tensilica, Inc.
*
* Chris Zankel <chris@zankel.net>
*
@ -366,6 +366,41 @@ ENTRY(_DebugInterruptVector)
ENDPROC(_DebugInterruptVector)
/*
* Medium priority level interrupt vectors
*
* Each takes less than 16 (0x10) bytes, no literals, by placing
* the extra 8 bytes that would otherwise be required in the window
* vectors area where there is space. With relocatable vectors,
* all vectors are within ~ 4 kB range of each other, so we can
* simply jump (J) to another vector without having to use JX.
*
* common_exception code gets current IRQ level in PS.INTLEVEL
* and preserves it for the IRQ handling time.
*/
.macro irq_entry_level level
.if XCHAL_EXCM_LEVEL >= \level
.section .Level\level\()InterruptVector.text, "ax"
ENTRY(_Level\level\()InterruptVector)
wsr a0, epc1
rsr a0, epc\level
xsr a0, epc1
# branch to user or kernel vector
j _SimulateUserKernelVectorException
.endif
.endm
irq_entry_level 2
irq_entry_level 3
irq_entry_level 4
irq_entry_level 5
irq_entry_level 6
/* Window overflow and underflow handlers.
* The handlers must be 64 bytes apart, first starting with the underflow
* handlers underflow-4 to underflow-12, then the overflow handlers
@ -396,6 +431,26 @@ ENTRY_ALIGN64(_WindowOverflow4)
ENDPROC(_WindowOverflow4)
#if XCHAL_EXCM_LEVEL >= 2
/* Not a window vector - but a convenient location
* (where we know there's space) for continuation of
* medium priority interrupt dispatch code.
* On entry here, a0 contains PS, and EPC2 contains saved a0:
*/
.align 4
_SimulateUserKernelVectorException:
wsr a0, excsave2
movi a0, 4 # LEVEL1_INTERRUPT cause
wsr a0, exccause
rsr a0, ps
bbsi.l a0, PS_UM_BIT, 1f # branch if user mode
rsr a0, excsave2 # restore a0
j _KernelExceptionVector # simulate kernel vector exception
1: rsr a0, excsave2 # restore a0
j _UserExceptionVector # simulate user vector exception
#endif
/* 4-Register Window Underflow Vector (Handler) */
ENTRY_ALIGN64(_WindowUnderflow4)

68
arch/xtensa/kernel/vmlinux.lds.S
View File

@ -7,7 +7,7 @@
* License. See the file "COPYING" in the main directory of this archive
* for more details.
*
* Copyright (C) 2001 - 2005 Tensilica Inc.
* Copyright (C) 2001 - 2008 Tensilica Inc.
*
* Chris Zankel <chris@zankel.net>
* Marc Gauthier <marc@tensilica.com, marc@alumni.uwaterloo.ca>
@ -134,6 +134,26 @@ SECTIONS
RELOCATE_ENTRY(_WindowVectors_text,
.WindowVectors.text);
#if XCHAL_EXCM_LEVEL >= 2
RELOCATE_ENTRY(_Level2InterruptVector_text,
.Level2InterruptVector.text);
#endif
#if XCHAL_EXCM_LEVEL >= 3
RELOCATE_ENTRY(_Level3InterruptVector_text,
.Level3InterruptVector.text);
#endif
#if XCHAL_EXCM_LEVEL >= 4
RELOCATE_ENTRY(_Level4InterruptVector_text,
.Level4InterruptVector.text);
#endif
#if XCHAL_EXCM_LEVEL >= 5
RELOCATE_ENTRY(_Level5InterruptVector_text,
.Level5InterruptVector.text);
#endif
#if XCHAL_EXCM_LEVEL >= 6
RELOCATE_ENTRY(_Level6InterruptVector_text,
.Level6InterruptVector.text);
#endif
RELOCATE_ENTRY(_KernelExceptionVector_text,
.KernelExceptionVector.text);
RELOCATE_ENTRY(_UserExceptionVector_text,
@ -177,11 +197,53 @@ SECTIONS
XCHAL_DEBUG_VECTOR_VADDR,
4,
.DebugInterruptVector.literal)
#undef LAST
#define LAST .DebugInterruptVector.text
#if XCHAL_EXCM_LEVEL >= 2
SECTION_VECTOR (_Level2InterruptVector_text,
.Level2InterruptVector.text,
XCHAL_INTLEVEL2_VECTOR_VADDR,
SIZEOF(LAST), LAST)
# undef LAST
# define LAST .Level2InterruptVector.text
#endif
#if XCHAL_EXCM_LEVEL >= 3
SECTION_VECTOR (_Level3InterruptVector_text,
.Level3InterruptVector.text,
XCHAL_INTLEVEL3_VECTOR_VADDR,
SIZEOF(LAST), LAST)
# undef LAST
# define LAST .Level3InterruptVector.text
#endif
#if XCHAL_EXCM_LEVEL >= 4
SECTION_VECTOR (_Level4InterruptVector_text,
.Level4InterruptVector.text,
XCHAL_INTLEVEL4_VECTOR_VADDR,
SIZEOF(LAST), LAST)
# undef LAST
# define LAST .Level4InterruptVector.text
#endif
#if XCHAL_EXCM_LEVEL >= 5
SECTION_VECTOR (_Level5InterruptVector_text,
.Level5InterruptVector.text,
XCHAL_INTLEVEL5_VECTOR_VADDR,
SIZEOF(LAST), LAST)
# undef LAST
# define LAST .Level5InterruptVector.text
#endif
#if XCHAL_EXCM_LEVEL >= 6
SECTION_VECTOR (_Level6InterruptVector_text,
.Level6InterruptVector.text,
XCHAL_INTLEVEL6_VECTOR_VADDR,
SIZEOF(LAST), LAST)
# undef LAST
# define LAST .Level6InterruptVector.text
#endif
SECTION_VECTOR (_KernelExceptionVector_literal,
.KernelExceptionVector.literal,
XCHAL_KERNEL_VECTOR_VADDR - 4,
SIZEOF(.DebugInterruptVector.text),
.DebugInterruptVector.text)
SIZEOF(LAST), LAST)
#undef LAST
SECTION_VECTOR (_KernelExceptionVector_text,
.KernelExceptionVector.text,
XCHAL_KERNEL_VECTOR_VADDR,