ARC: Support for high priority interrupts in the in-core intc
There is a bit of hack/kludge right now where we disable preemption if a
L2 (High prio) IRQ is taken while L1 (Low prio) is active.
Need to revisit this
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
diff --git a/arch/arc/kernel/entry.S b/arch/arc/kernel/entry.S
index 76697ae..e33a0bf 100644
--- a/arch/arc/kernel/entry.S
+++ b/arch/arc/kernel/entry.S
@@ -31,6 +31,8 @@
* exception. Thus FAKE RTIE needed in low level Priv-Violation handler.
* Instr Error could also cause similar scenario, so same there as well.
*
+ * Vineetg: March 2009 (Supporting 2 levels of Interrupts)
+ *
* Vineetg: Aug 28th 2008: Bug #94984
* -Zero Overhead Loop Context shd be cleared when entering IRQ/EXcp/Trap
* Normally CPU does this automatically, however when doing FAKE rtie,
@@ -96,13 +98,25 @@
VECTOR instr_service ; 0x10, Instrn Error (0x2)
; ******************** Device ISRs **********************
+#ifdef CONFIG_ARC_IRQ3_LV2
+VECTOR handle_interrupt_level2
+#else
VECTOR handle_interrupt_level1
+#endif
VECTOR handle_interrupt_level1
+#ifdef CONFIG_ARC_IRQ5_LV2
+VECTOR handle_interrupt_level2
+#else
VECTOR handle_interrupt_level1
+#endif
+#ifdef CONFIG_ARC_IRQ6_LV2
+VECTOR handle_interrupt_level2
+#else
VECTOR handle_interrupt_level1
+#endif
.rept 25
VECTOR handle_interrupt_level1 ; Other devices
@@ -139,6 +153,17 @@
int1_saved_reg:
.zero 4
+/* Each Interrupt level needs it's own scratch */
+#ifdef CONFIG_ARC_COMPACT_IRQ_LEVELS
+
+ .section .data ; NOT .global
+ .type int2_saved_reg, @object
+ .size int2_saved_reg, 4
+int2_saved_reg:
+ .zero 4
+
+#endif
+
; ---------------------------------------------
.section .text, "ax",@progbits
@@ -152,6 +177,55 @@
;##################### Interrupt Handling ##############################
+#ifdef CONFIG_ARC_COMPACT_IRQ_LEVELS
+; ---------------------------------------------
+; Level 2 ISR: Can interrupt a Level 1 ISR
+; ---------------------------------------------
+ARC_ENTRY handle_interrupt_level2
+
+ ; TODO-vineetg for SMP this wont work
+ ; free up r9 as scratchpad
+ st r9, [@int2_saved_reg]
+
+ ;Which mode (user/kernel) was the system in when intr occured
+ lr r9, [status32_l2]
+
+ SWITCH_TO_KERNEL_STK
+ SAVE_ALL_INT2
+
+ ;------------------------------------------------------
+ ; if L2 IRQ interrupted a L1 ISR, disable preemption
+ ;------------------------------------------------------
+
+ ld r9, [sp, PT_status32] ; get statu32_l2 (saved in pt_regs)
+ bbit0 r9, STATUS_A1_BIT, 1f ; L1 not active when L2 IRQ, so normal
+
+ ; A1 is set in status32_l2
+ ; bump thread_info->preempt_count (Disable preemption)
+ GET_CURR_THR_INFO_FROM_SP r10
+ ld r9, [r10, THREAD_INFO_PREEMPT_COUNT]
+ add r9, r9, 1
+ st r9, [r10, THREAD_INFO_PREEMPT_COUNT]
+
+1:
+ ;------------------------------------------------------
+ ; setup params for Linux common ISR and invoke it
+ ;------------------------------------------------------
+ lr r0, [icause2]
+ and r0, r0, 0x1f
+
+ bl.d @arch_do_IRQ
+ mov r1, sp
+
+ mov r8,0x2
+ sr r8, [AUX_IRQ_LV12] ; clear bit in Sticky Status Reg
+
+ b ret_from_exception
+
+ARC_EXIT handle_interrupt_level2
+
+#endif
+
; ---------------------------------------------
; Level 1 ISR
; ---------------------------------------------
@@ -619,6 +693,49 @@
not_exception:
+#ifdef CONFIG_ARC_COMPACT_IRQ_LEVELS
+
+ bbit0 r10, STATUS_A2_BIT, not_level2_interrupt
+
+ ;------------------------------------------------------------------
+ ; if L2 IRQ interrupted a L1 ISR, we'd disbaled preemption earlier
+ ; so that sched doesnt move to new task, causing L1 to be delayed
+ ; undeterministically. Now that we've achieved that, lets reset
+ ; things to what they were, before returning from L2 context
+ ;----------------------------------------------------------------
+
+ ld r9, [sp, PT_orig_r8] ; get orig_r8 to make sure it is
+ brne r9, orig_r8_IS_IRQ2, 149f ; infact a L2 ISR ret path
+
+ ld r9, [sp, PT_status32] ; get statu32_l2 (saved in pt_regs)
+ bbit0 r9, STATUS_A1_BIT, 149f ; L1 not active when L2 IRQ, so normal
+
+ ; A1 is set in status32_l2
+ ; decrement thread_info->preempt_count (re-enable preemption)
+ GET_CURR_THR_INFO_FROM_SP r10
+ ld r9, [r10, THREAD_INFO_PREEMPT_COUNT]
+
+ ; paranoid check, given A1 was active when A2 happened, preempt count
+ ; must not be 0 beccause we would have incremented it.
+ ; If this does happen we simply HALT as it means a BUG !!!
+ cmp r9, 0
+ bnz 2f
+ flag 1
+
+2:
+ sub r9, r9, 1
+ st r9, [r10, THREAD_INFO_PREEMPT_COUNT]
+
+149:
+ ;return from level 2
+ RESTORE_ALL_INT2
+debug_marker_l2:
+ rtie
+
+not_level2_interrupt:
+
+#endif
+
bbit0 r10, STATUS_A1_BIT, not_level1_interrupt
;return from level 1