[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: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 21 insertions, 7 deletions

diff --git a/arch/ppc64/kernel/pmac_smp.c b/arch/ppc64/kernel/pmac_smp.c
index c27588ede2f..a23de37227b 100644
--- a/arch/ppc64/kernel/pmac_smp.c
+++ b/arch/ppc64/kernel/pmac_smp.c
@@ -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:
-                        pmac_tb_freeze = smp_core99_cypress_tb_freeze;
-                        printk(KERN_INFO "Timebase clock is Cypress chip\n");
+                        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;