Merge git://git.kernel.org/pub/scm/linux/kernel/git/paulus/powerpc-merge

1 files changed, 63 insertions, 1 deletions

diff --git a/arch/ppc/platforms/chrp_time.c b/arch/ppc/platforms/chrp_time.c
index 29d074c305f0..57753a55b580 100644
--- a/arch/ppc/platforms/chrp_time.c
+++ b/arch/ppc/platforms/chrp_time.c
@@ -163,13 +163,75 @@ unsigned long chrp_get_rtc_time(void)
         return mktime(year, mon, day, hour, min, sec);
 }
 
+/*
+ * Calibrate the decrementer frequency with the VIA timer 1.
+ */
+#define VIA_TIMER_FREQ_6        4700000 /* time 1 frequency * 6 */
+
+/* VIA registers */
+#define RS              0x200           /* skip between registers */
+#define T1CL            (4*RS)          /* Timer 1 ctr/latch (low 8 bits) */
+#define T1CH            (5*RS)          /* Timer 1 counter (high 8 bits) */
+#define T1LL            (6*RS)          /* Timer 1 latch (low 8 bits) */
+#define T1LH            (7*RS)          /* Timer 1 latch (high 8 bits) */
+#define ACR             (11*RS)         /* Auxiliary control register */
+#define IFR             (13*RS)         /* Interrupt flag register */
+
+/* Bits in ACR */
+#define T1MODE          0xc0            /* Timer 1 mode */
+#define T1MODE_CONT     0x40            /*  continuous interrupts */
+
+/* Bits in IFR and IER */
+#define T1_INT          0x40            /* Timer 1 interrupt */
+
+static int __init chrp_via_calibrate_decr(void)
+{
+        struct device_node *vias;
+        volatile unsigned char __iomem *via;
+        int count = VIA_TIMER_FREQ_6 / 100;
+        unsigned int dstart, dend;
+
+        vias = find_devices("via-cuda");
+        if (vias == 0)
+                vias = find_devices("via");
+        if (vias == 0 || vias->n_addrs == 0)
+                return 0;
+        via = ioremap(vias->addrs[0].address, vias->addrs[0].size);
+
+        /* set timer 1 for continuous interrupts */
+        out_8(&via[ACR], (via[ACR] & ~T1MODE) | T1MODE_CONT);
+        /* set the counter to a small value */
+        out_8(&via[T1CH], 2);
+        /* set the latch to `count' */
+        out_8(&via[T1LL], count);
+        out_8(&via[T1LH], count >> 8);
+        /* wait until it hits 0 */
+        while ((in_8(&via[IFR]) & T1_INT) == 0)
+                ;
+        dstart = get_dec();
+        /* clear the interrupt & wait until it hits 0 again */
+        in_8(&via[T1CL]);
+        while ((in_8(&via[IFR]) & T1_INT) == 0)
+                ;
+        dend = get_dec();
+
+        tb_ticks_per_jiffy = (dstart - dend) / ((6 * HZ)/100);
+        tb_to_us = mulhwu_scale_factor(dstart - dend, 60000);
+
+        printk(KERN_INFO "via_calibrate_decr: ticks per jiffy = %u (%u ticks)\n",
+               tb_ticks_per_jiffy, dstart - dend);
+
+        iounmap(via);
+        
+        return 1;
+}
 
 void __init chrp_calibrate_decr(void)
 {
         struct device_node *cpu;
         unsigned int freq, *fp;
 
-        if (via_calibrate_decr())
+        if (chrp_via_calibrate_decr())
                 return;
 
         /*