diff options
Diffstat (limited to 'arch/powerpc')
| -rw-r--r-- | arch/powerpc/Kconfig | 7 | ||||
| -rw-r--r-- | arch/powerpc/kernel/Makefile | 1 | ||||
| -rw-r--r-- | arch/powerpc/kernel/smp-tbsync.c | 171 |
3 files changed, 179 insertions, 0 deletions
diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig index 3cf03ab4611..f4e25c648fb 100644 --- a/arch/powerpc/Kconfig +++ b/arch/powerpc/Kconfig @@ -300,6 +300,7 @@ config PPC_PMAC64 bool depends on PPC_PMAC && POWER4 select U3_DART + select GENERIC_TBSYNC default y config PPC_PREP @@ -314,6 +315,7 @@ config PPC_MAPLE bool " Maple 970FX Evaluation Board" select U3_DART select MPIC_BROKEN_U3 + select GENERIC_TBSYNC default n help This option enables support for the Maple 970FX Evaluation Board. @@ -386,6 +388,11 @@ config PPC_MPC106 bool default n +config GENERIC_TBSYNC + bool + default y if CONFIG_PPC32 && CONFIG_SMP + default n + source "drivers/cpufreq/Kconfig" config CPU_FREQ_PMAC diff --git a/arch/powerpc/kernel/Makefile b/arch/powerpc/kernel/Makefile index 7a3e1155ac9..631149ea93d 100644 --- a/arch/powerpc/kernel/Makefile +++ b/arch/powerpc/kernel/Makefile @@ -21,6 +21,7 @@ obj-$(CONFIG_PPC_RTAS) += rtas.o obj-$(CONFIG_RTAS_FLASH) += rtas_flash.o obj-$(CONFIG_RTAS_PROC) += rtas-proc.o obj-$(CONFIG_IBMVIO) += vio.o +obj-$(CONFIG_GENERIC_TBSYNC) += smp-tbsync.o ifeq ($(CONFIG_PPC_MERGE),y) diff --git a/arch/powerpc/kernel/smp-tbsync.c b/arch/powerpc/kernel/smp-tbsync.c new file mode 100644 index 00000000000..9adef3bddad --- /dev/null +++ b/arch/powerpc/kernel/smp-tbsync.c @@ -0,0 +1,171 @@ +/* + * 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 u64 tb; + volatile u64 mark; + volatile int cmd; + volatile int handshake; + int filler[2]; + + volatile int ack; + int filler2[7]; + + volatile int race_result; +} *tbsync; + +static volatile int running; + +static void __devinit enter_contest(u64 mark, long add) +{ + while (get_tb() < mark) + tbsync->race_result = add; +} + +void __devinit smp_generic_take_timebase(void) +{ + int cmd; + u64 tb; + + local_irq_disable(); + while (!running) + barrier(); + rmb(); + + for (;;) { + tbsync->ack = 1; + while (!tbsync->handshake) + barrier(); + rmb(); + + cmd = tbsync->cmd; + tb = tbsync->tb; + mb(); + tbsync->ack = 0; + if (cmd == kExit) + break; + + while (tbsync->handshake) + barrier(); + if (cmd == kSetAndTest) + set_tb(tb >> 32, tb & 0xfffffffful); + enter_contest(tbsync->mark, -1); + } + local_irq_enable(); +} + +static int __devinit start_contest(int cmd, long offset, int num) +{ + int i, score=0; + u64 tb; + long mark; + + tbsync->cmd = cmd; + + local_irq_disable(); + for (i = -3; i < num; ) { + tb = get_tb() + 400; + tbsync->tb = tb + offset; + tbsync->mark = mark = tb + 400; + + wmb(); + + tbsync->handshake = 1; + while (tbsync->ack) + barrier(); + + while (get_tb() <= tb) + barrier(); + tbsync->handshake = 0; + enter_contest(mark, 1); + + while (!tbsync->ack) + barrier(); + + 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) + barrier(); + + printk("Got ack\n"); + + /* 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) + barrier(); + tbsync->handshake = 0; + kfree(tbsync); + tbsync = NULL; + running = 0; +} |