Blackfin: initial preempt support while returning from interrupt

Signed-off-by: Barry Song <barry.song@analog.com>
Signed-off-by: Mike Frysinger <vapier@gentoo.org>

2 files changed, 126 insertions, 3 deletions

diff --git a/arch/blackfin/mach-common/entry.S b/arch/blackfin/mach-common/entry.S
index af1bffa21dc1..16ea779c3a6f 100644
--- a/arch/blackfin/mach-common/entry.S
+++ b/arch/blackfin/mach-common/entry.S
@@ -889,6 +889,66 @@ ENTRY(_ret_from_exception)
         rts;
 ENDPROC(_ret_from_exception)
 
+#if defined(CONFIG_PREEMPT)
+
+ENTRY(_up_to_irq14)
+#if ANOMALY_05000281 || ANOMALY_05000461
+        r0.l = lo(SAFE_USER_INSTRUCTION);
+        r0.h = hi(SAFE_USER_INSTRUCTION);
+        reti = r0;
+#endif
+
+#ifdef CONFIG_DEBUG_HWERR
+        /* enable irq14 & hwerr interrupt, until we transition to _evt_evt14 */
+        r0 = (EVT_IVG14 | EVT_IVHW | EVT_IRPTEN | EVT_EVX | EVT_NMI | EVT_RST | EVT_EMU);
+#else
+        /* Only enable irq14 interrupt, until we transition to _evt_evt14 */
+        r0 = (EVT_IVG14 | EVT_IRPTEN | EVT_EVX | EVT_NMI | EVT_RST | EVT_EMU);
+#endif
+        sti r0;
+
+        p0.l = lo(EVT14);
+        p0.h = hi(EVT14);
+        p1.l = _evt_up_evt14;
+        p1.h = _evt_up_evt14;
+        [p0] = p1;
+        csync;
+
+        raise 14;
+1:
+        jump 1b;
+ENDPROC(_up_to_irq14)
+
+ENTRY(_evt_up_evt14)
+#ifdef CONFIG_DEBUG_HWERR
+        r0 = (EVT_IVHW | EVT_IRPTEN | EVT_EVX | EVT_NMI | EVT_RST | EVT_EMU);
+        sti r0;
+#else
+        cli r0;
+#endif
+#ifdef CONFIG_TRACE_IRQFLAGS
+        [--sp] = rets;
+        sp += -12;
+        call _trace_hardirqs_off;
+        sp += 12;
+        rets = [sp++];
+#endif
+        [--sp] = RETI;
+        SP += 4;
+
+        /* restore normal evt14 */
+        p0.l = lo(EVT14);
+        p0.h = hi(EVT14);
+        p1.l = _evt_evt14;
+        p1.h = _evt_evt14;
+        [p0] = p1;
+        csync;
+
+        rts;
+ENDPROC(_evt_up_evt14)
+
+#endif
+
 #ifdef CONFIG_IPIPE
 
 _resume_kernel_from_int:
@@ -902,8 +962,54 @@ _resume_kernel_from_int:
         ( r7:4, p5:3 ) = [sp++];
         rets = [sp++];
         rts
+#elif defined(CONFIG_PREEMPT)
+
+_resume_kernel_from_int:
+        /* check preempt_count */
+        r7 = sp;
+        r4.l = lo(ALIGN_PAGE_MASK);
+        r4.h = hi(ALIGN_PAGE_MASK);
+        r7 = r7 & r4;
+        p5 = r7;
+        r7 = [p5 + TI_PREEMPT];
+        cc = r7 == 0x0;
+        if !cc jump .Lreturn_to_kernel;
+.Lneed_schedule:
+        r7 = [p5 + TI_FLAGS];
+        r4.l = lo(_TIF_WORK_MASK);
+        r4.h = hi(_TIF_WORK_MASK);
+        r7 =  r7 & r4;
+        cc = BITTST(r7, TIF_NEED_RESCHED);
+        if !cc jump .Lreturn_to_kernel;
+        /*
+         * let schedule done at level 15, otherwise sheduled process will run
+         * at high level and block low level interrupt
+         */
+        r6 = reti;  /* save reti */
+        r5.l = .Lkernel_schedule;
+        r5.h = .Lkernel_schedule;
+        reti = r5;
+        rti;
+.Lkernel_schedule:
+        [--sp] = rets;
+        sp += -12;
+        pseudo_long_call _preempt_schedule_irq, p4;
+        sp += 12;
+        rets = [sp++];
+
+        [--sp] = rets;
+        sp += -12;
+        /* up to irq14 so that reti after restore_all can return to irq15(kernel) */
+        pseudo_long_call _up_to_irq14, p4;
+        sp += 12;
+        rets = [sp++];
+
+        reti = r6; /* restore reti so that origin process can return to interrupted point */
+
+        jump .Lneed_schedule;
 #else
-#define _resume_kernel_from_int  2f
+
+#define _resume_kernel_from_int .Lreturn_to_kernel
 #endif
 
 ENTRY(_return_from_int)
@@ -913,7 +1019,7 @@ ENTRY(_return_from_int)
         p2.h = hi(ILAT);
         r0 = [p2];
         cc = bittst (r0, EVT_IVG15_P);
-        if cc jump 2f;
+        if cc jump .Lreturn_to_kernel;
 
         /* if not return to user mode, get out */
         p2.l = lo(IPEND);
@@ -945,7 +1051,7 @@ ENTRY(_return_from_int)
         STI r0;
         raise 15;       /* raise evt15 to do signal or reschedule */
         rti;
-2:
+.Lreturn_to_kernel:
         rts;
 ENDPROC(_return_from_int)
 
diff --git a/arch/blackfin/mach-common/interrupt.S b/arch/blackfin/mach-common/interrupt.S
index cee62cf4acd4..2df37db3b49b 100644
--- a/arch/blackfin/mach-common/interrupt.S
+++ b/arch/blackfin/mach-common/interrupt.S
@@ -116,7 +116,24 @@ __common_int_entry:
         cc = r0 == 0;
         if cc jump .Lcommon_restore_context;
 #else /* CONFIG_IPIPE */
+
+#ifdef CONFIG_PREEMPT
+        r7 = sp;
+        r4.l = lo(ALIGN_PAGE_MASK);
+        r4.h = hi(ALIGN_PAGE_MASK);
+        r7 = r7 & r4;
+        p5 = r7;
+        r7 = [p5 + TI_PREEMPT]; /* get preempt count */
+        r7 += 1;                /* increment it */
+        [p5 + TI_PREEMPT] = r7;
+#endif
         pseudo_long_call _do_irq, p2;
+
+#ifdef CONFIG_PREEMPT
+        r7 += -1;
+        [p5 + TI_PREEMPT] = r7; /* restore preempt count */
+#endif
+
         SP += 12;
 #endif /* CONFIG_IPIPE */
         pseudo_long_call _return_from_int, p2;