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Commit f10d20c1 authored by Benjamin Herrenschmidt's avatar Benjamin Herrenschmidt Committed by Linus Torvalds
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[PATCH] ppc64: Fix g5 hw timebase sync 



The hardware sync of the timebase on SMP G5s uses a black magic
incantation to the i2c clock chip that was inspired from what Darwin
does.

However, this was an earlier version of Darwin that was ...  buggy !
heh.  This causes the latest models to break though when starting SMP,
so it's worth fixing.

Here's a new version of the incantation based on careful transcription
of the said incantations as found in the latest version of apple's
temple.

Signed-off-by: default avatarBenjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent e16fa6b9

arch/ppc64/kernel/pmac_smp.c

+21 −7
Original line number Diff line number Diff line
@@ -68,6 +68,7 @@ extern struct smp_ops_t *smp_ops; 


static void (*pmac_tb_freeze)(int freeze);

static struct device_node *pmac_tb_clock_chip_host;

static u8 pmac_tb_pulsar_addr;

static DEFINE_SPINLOCK(timebase_lock);

static unsigned long timebase;
@@ -106,12 +107,9 @@ static void smp_core99_pulsar_tb_freeze(int freeze) 
	u8 data;

	int rc;



	/* Strangely, the device-tree says address is 0xd2, but darwin

	 * accesses 0xd0 ...

	 */

	pmac_low_i2c_setmode(pmac_tb_clock_chip_host, pmac_low_i2c_mode_combined);

	rc = pmac_low_i2c_xfer(pmac_tb_clock_chip_host,

			       0xd4 | pmac_low_i2c_read,

			       pmac_tb_pulsar_addr | pmac_low_i2c_read,

			       0x2e, &data, 1);

	if (rc != 0)

		goto bail;
@@ -120,7 +118,7 @@ static void smp_core99_pulsar_tb_freeze(int freeze) 


	pmac_low_i2c_setmode(pmac_tb_clock_chip_host, pmac_low_i2c_mode_stdsub);

	rc = pmac_low_i2c_xfer(pmac_tb_clock_chip_host,

			       0xd4 | pmac_low_i2c_write,

			       pmac_tb_pulsar_addr | pmac_low_i2c_write,

			       0x2e, &data, 1);

 bail:

	if (rc != 0) {
@@ -185,6 +183,12 @@ static int __init smp_core99_probe(void) 
	if (ncpus <= 1)

		return 1;



	/* HW sync only on these platforms */

	if (!machine_is_compatible("PowerMac7,2") &&

	    !machine_is_compatible("PowerMac7,3") &&

	    !machine_is_compatible("RackMac3,1"))

		goto nohwsync;



	/* Look for the clock chip */

	for (cc = NULL; (cc = of_find_node_by_name(cc, "i2c-hwclock")) != NULL;) {

		struct device_node *p = of_get_parent(cc);
@@ -198,11 +202,18 @@ static int __init smp_core99_probe(void) 
			goto next;

		switch (*reg) {

		case 0xd2:

			if (device_is_compatible(cc, "pulsar-legacy-slewing")) {

				pmac_tb_freeze = smp_core99_pulsar_tb_freeze;

				pmac_tb_pulsar_addr = 0xd2;

				printk(KERN_INFO "Timebase clock is Pulsar chip\n");

			} else if (device_is_compatible(cc, "cy28508")) {

				pmac_tb_freeze = smp_core99_cypress_tb_freeze;

				printk(KERN_INFO "Timebase clock is Cypress chip\n");

			}

			break;

		case 0xd4:

			pmac_tb_freeze = smp_core99_pulsar_tb_freeze;

			pmac_tb_pulsar_addr = 0xd4;

			printk(KERN_INFO "Timebase clock is Pulsar chip\n");

			break;

		}
@@ -210,12 +221,15 @@ static int __init smp_core99_probe(void) 
			pmac_tb_clock_chip_host = p;

			smp_ops->give_timebase = smp_core99_give_timebase;

			smp_ops->take_timebase = smp_core99_take_timebase;

			of_node_put(cc);

			of_node_put(p);

			break;

		}

	next:

		of_node_put(p);

	}



 nohwsync:

	mpic_request_ipis();



	return ncpus;