Linux-2.6.12-rc2
Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.
Let it rip!
diff --git a/arch/ppc/kernel/smp-tbsync.c b/arch/ppc/kernel/smp-tbsync.c
new file mode 100644
index 0000000..2c9cd95
--- /dev/null
+++ b/arch/ppc/kernel/smp-tbsync.c
@@ -0,0 +1,181 @@
+/*
+ * Smp timebase synchronization for ppc.
+ *
+ * Copyright (C) 2003 Samuel Rydh (samuel@ibrium.se)
+ *
+ */
+
+#include <linux/config.h>
+#include <linux/kernel.h>
+#include <linux/sched.h>
+#include <linux/smp.h>
+#include <linux/unistd.h>
+#include <linux/init.h>
+#include <asm/atomic.h>
+#include <asm/smp.h>
+#include <asm/time.h>
+
+#define NUM_ITER 300
+
+enum {
+ kExit=0, kSetAndTest, kTest
+};
+
+static struct {
+ volatile int tbu;
+ volatile int tbl;
+ volatile int mark;
+ volatile int cmd;
+ volatile int handshake;
+ int filler[3];
+
+ volatile int ack;
+ int filler2[7];
+
+ volatile int race_result;
+} *tbsync;
+
+static volatile int running;
+
+static void __devinit
+enter_contest( int mark, int add )
+{
+ while( (int)(get_tbl() - mark) < 0 )
+ tbsync->race_result = add;
+}
+
+void __devinit
+smp_generic_take_timebase( void )
+{
+ int cmd, tbl, tbu;
+
+ local_irq_disable();
+ while( !running )
+ ;
+ rmb();
+
+ for( ;; ) {
+ tbsync->ack = 1;
+ while( !tbsync->handshake )
+ ;
+ rmb();
+
+ cmd = tbsync->cmd;
+ tbl = tbsync->tbl;
+ tbu = tbsync->tbu;
+ tbsync->ack = 0;
+ if( cmd == kExit )
+ return;
+
+ if( cmd == kSetAndTest ) {
+ while( tbsync->handshake )
+ ;
+ asm volatile ("mttbl %0" :: "r" (tbl) );
+ asm volatile ("mttbu %0" :: "r" (tbu) );
+ } else {
+ while( tbsync->handshake )
+ ;
+ }
+ enter_contest( tbsync->mark, -1 );
+ }
+ local_irq_enable();
+}
+
+static int __devinit
+start_contest( int cmd, int offset, int num )
+{
+ int i, tbu, tbl, mark, score=0;
+
+ tbsync->cmd = cmd;
+
+ local_irq_disable();
+ for( i=-3; i<num; ) {
+ tbl = get_tbl() + 400;
+ tbsync->tbu = tbu = get_tbu();
+ tbsync->tbl = tbl + offset;
+ tbsync->mark = mark = tbl + 400;
+
+ wmb();
+
+ tbsync->handshake = 1;
+ while( tbsync->ack )
+ ;
+
+ while( (int)(get_tbl() - tbl) <= 0 )
+ ;
+ tbsync->handshake = 0;
+ enter_contest( mark, 1 );
+
+ while( !tbsync->ack )
+ ;
+
+ if( tbsync->tbu != get_tbu() || ((tbsync->tbl ^ get_tbl()) & 0x80000000) )
+ continue;
+ if( i++ > 0 )
+ score += tbsync->race_result;
+ }
+ local_irq_enable();
+ return score;
+}
+
+void __devinit
+smp_generic_give_timebase( void )
+{
+ int i, score, score2, old, min=0, max=5000, offset=1000;
+
+ printk("Synchronizing timebase\n");
+
+ /* if this fails then this kernel won't work anyway... */
+ tbsync = kmalloc( sizeof(*tbsync), GFP_KERNEL );
+ memset( tbsync, 0, sizeof(*tbsync) );
+ mb();
+ running = 1;
+
+ while( !tbsync->ack )
+ ;
+
+ /* binary search */
+ for( old=-1 ; old != offset ; offset=(min+max)/2 ) {
+ score = start_contest( kSetAndTest, offset, NUM_ITER );
+
+ printk("score %d, offset %d\n", score, offset );
+
+ if( score > 0 )
+ max = offset;
+ else
+ min = offset;
+ old = offset;
+ }
+ score = start_contest( kSetAndTest, min, NUM_ITER );
+ score2 = start_contest( kSetAndTest, max, NUM_ITER );
+
+ printk( "Min %d (score %d), Max %d (score %d)\n", min, score, max, score2 );
+ score = abs( score );
+ score2 = abs( score2 );
+ offset = (score < score2) ? min : max;
+
+ /* guard against inaccurate mttb */
+ for( i=0; i<10; i++ ) {
+ start_contest( kSetAndTest, offset, NUM_ITER/10 );
+
+ if( (score2=start_contest(kTest, offset, NUM_ITER)) < 0 )
+ score2 = -score2;
+ if( score2 <= score || score2 < 20 )
+ break;
+ }
+ printk("Final offset: %d (%d/%d)\n", offset, score2, NUM_ITER );
+
+ /* exiting */
+ tbsync->cmd = kExit;
+ wmb();
+ tbsync->handshake = 1;
+ while( tbsync->ack )
+ ;
+ tbsync->handshake = 0;
+ kfree( tbsync );
+ tbsync = NULL;
+ running = 0;
+
+ /* all done */
+ smp_tb_synchronized = 1;
+}