Changeset 327 for trunk/hal/x86_64/core/hal_apic.c

Timestamp:

Aug 6, 2017, 7:58:22 PM (7 years ago)

Author:

max@…

Message:

Clean up, and fix several SMP-related issues. The LAPIC timer is still
drifting away between CPUs in some cases, needs to be investigated.

File:

• trunk/hal/x86_64/core/hal_apic.c (modified) (9 diffs)

trunk/hal/x86_64/core/hal_apic.c

@@ -48 +48 @@
          * Disable the PIC (8259A). We are going to use IOAPIC instead.
          */
-        out8(PIC1_DATA, 0xff);
-        out8(PIC2_DATA, 0xff);
-}
-
-/* -------------------------------------------------------------------------- */
-
-uint64_t pit_ticks_base __in_kdata = 0;
+        out8(PIC1_DATA, 0xFF);
+        out8(PIC2_DATA, 0xFF);
+}
+
+/* -------------------------------------------------------------------------- */
+
+static uint64_t pit_ticks_base __in_kdata = 0;
+static uint16_t pit_ticks_last __in_kdata = 0;
 
 #define PIT_FREQUENCY   1193182
@@ -69 +70 @@
 #       define CMD_MODE2        0x04 /* Rate Generator */
 #       define CMD_MODE3        0x06 /* Square Wave */
-#       define CMD_MODE4        0x08 /* Software Trigerred Strobe */
-#       define CMD_MODE5        0x0a /* Hardware Trigerred Strobe */
+#       define CMD_MODE4        0x08 /* Software Triggered Strobe */
+#       define CMD_MODE5        0x0a /* Hardware Triggered Strobe */
 #       define CMD_LATCH        0x00 /* latch counter for reading */
 #       define CMD_LSB          0x10 /* LSB, 8 bits */
@@ -82 +83 @@
 void hal_pit_reset(uint16_t val)
 {
+        uint8_t lo, hi;
+
         pit_ticks_base = 0;
 
-        /* Initialize PIT clock 0 to value given. */
+        /* Set the initial counter value for clock 0. */
         out8(PIT_CMD, CMD_COUNTER0|CMD_MODE2|CMD_16BIT);
         out8(PIT_TIMER0, (val >> 0) & 0xFF);
         out8(PIT_TIMER0, (val >> 8) & 0xFF);
+
+        /*
+         * Read the current value, to initialize pit_ticks_last. Not extremely
+         * accurate, but fine.
+         */
+        out8(PIT_CMD, CMD_COUNTER0|CMD_LATCH);
+        lo = in8(PIT_TIMER0);
+        hi = in8(PIT_TIMER0);
+
+        pit_ticks_last = (hi << 8) | lo;
 }
 
@@ -93 +106 @@
 hal_pit_timer_read()
 {
-        static uint16_t last;
-
         uint8_t lo, hi;
         uint16_t ctr;
@@ -105 +116 @@
         ctr = (hi << 8) | lo;
 
-        /* If the counter has wrapped, assume we're into the next tick. */
-        if (ctr > last)
+        /* If the counter has overflown, assume we're into the next tick. */
+        if (ctr > pit_ticks_last)
                 pit_ticks_base += 0xFFFF;
-        last = ctr;
+        pit_ticks_last = ctr;
 
         ticks = pit_ticks_base + (0xFFFF - ctr);
@@ -124 +135 @@
 
         nticks = 0;
-        hal_pit_reset(0);
+        hal_pit_reset(0xFFFF);
 
         while (n > 0) {
@@ -130 +141 @@
                         /* Wait 1/muHZ sec = 1 microsecond */
                 }
-                nticks++;
+                nticks++; // ???
                 n--;
         }
@@ -388 +399 @@
 
         /* Reset the PIT */
-        hal_pit_reset(-1);
+        hal_pit_reset(0xFFFF);
 
         pittick = hal_pit_timer_read() + 1;
@@ -405 +416 @@
         lapictick1 = hal_lapic_read(LAPIC_CCR_TIMER);
 
+        if (lapictick1 > lapictick0)
+                x86_panic("LAPIC tick overflow!");
+
         /* Total number of LAPIC ticks per 1/HZ tick */
-        lapicticks = (lapictick1 - lapictick0);
-
-        /* Finally, calibrate the timer, an interrupt each 1s. */
-        lapicstart = - (lapicticks * 100);
+        lapicticks = (lapictick0 - lapictick1);
+
+        /*
+         * Finally, calibrate the timer, with an interrupt each 1s (10ms * 100).
+         */
+        lapicstart = (lapicticks * 100);
         hal_lapic_write(LAPIC_ICR_TIMER, lapicstart);
+        x86_printf("-> lapicticks: %z\n", (uint64_t)lapicticks);
 }