Merge git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6

[linux-2.6] / arch / x86 / kernel / hpet.c

diff --git a/arch/x86/kernel/hpet.c b/arch/x86/kernel/hpet.c
index ad2b15a1334d919419b9040b52c2062dd5d3666d..59fd3b6b13036e1e279e54d0e1e3d3f5ebb55166 100644 (file)
--- a/arch/x86/kernel/hpet.c
+++ b/arch/x86/kernel/hpet.c
@@ -359,6 +359,7 @@ static int hpet_clocksource_register(void)
 int __init hpet_enable(void)
 {
        unsigned long id;
+       int i;
 
        if (!is_hpet_capable())
                return 0;
@@ -369,6 +370,29 @@ int __init hpet_enable(void)
         * Read the period and check for a sane value:
         */
        hpet_period = hpet_readl(HPET_PERIOD);
+
+       /*
+        * AMD SB700 based systems with spread spectrum enabled use a
+        * SMM based HPET emulation to provide proper frequency
+        * setting. The SMM code is initialized with the first HPET
+        * register access and takes some time to complete. During
+        * this time the config register reads 0xffffffff. We check
+        * for max. 1000 loops whether the config register reads a non
+        * 0xffffffff value to make sure that HPET is up and running
+        * before we go further. A counting loop is safe, as the HPET
+        * access takes thousands of CPU cycles. On non SB700 based
+        * machines this check is only done once and has no side
+        * effects.
+        */
+       for (i = 0; hpet_readl(HPET_CFG) == 0xFFFFFFFF; i++) {
+               if (i == 1000) {
+                       printk(KERN_WARNING
+                              "HPET config register value = 0xFFFFFFFF. "
+                              "Disabling HPET\n");
+                       goto out_nohpet;
+               }
+       }
+
        if (hpet_period < HPET_MIN_PERIOD || hpet_period > HPET_MAX_PERIOD)
                goto out_nohpet;