1 files changed, 257 insertions, 0 deletions
diff --git a/roms/seabios/src/hw/timer.c b/roms/seabios/src/hw/timer.c
new file mode 100644
index 00000000..5edc9fdb
--- /dev/null
+++ b/roms/seabios/src/hw/timer.c
@@ -0,0 +1,257 @@
+// Internal timer and Intel 8253 Programmable Interrupt Timer (PIT) support.
+//
+// Copyright (C) 2008-2013  Kevin O'Connor <kevin@koconnor.net>
+//
+// This file may be distributed under the terms of the GNU LGPLv3 license.
+
+#include "biosvar.h" // GET_LOW
+#include "config.h" // CONFIG_*
+#include "output.h" // dprintf
+#include "stacks.h" // yield
+#include "util.h" // timer_setup
+#include "x86.h" // cpuid
+
+#define PORT_PIT_COUNTER0      0x0040
+#define PORT_PIT_COUNTER1      0x0041
+#define PORT_PIT_COUNTER2      0x0042
+#define PORT_PIT_MODE          0x0043
+#define PORT_PS2_CTRLB         0x0061
+
+// Bits for PORT_PIT_MODE
+#define PM_SEL_TIMER0   (0<<6)
+#define PM_SEL_TIMER1   (1<<6)
+#define PM_SEL_TIMER2   (2<<6)
+#define PM_SEL_READBACK (3<<6)
+#define PM_ACCESS_LATCH  (0<<4)
+#define PM_ACCESS_LOBYTE (1<<4)
+#define PM_ACCESS_HIBYTE (2<<4)
+#define PM_ACCESS_WORD   (3<<4)
+#define PM_MODE0 (0<<1)
+#define PM_MODE1 (1<<1)
+#define PM_MODE2 (2<<1)
+#define PM_MODE3 (3<<1)
+#define PM_MODE4 (4<<1)
+#define PM_MODE5 (5<<1)
+#define PM_CNT_BINARY (0<<0)
+#define PM_CNT_BCD    (1<<0)
+#define PM_READ_COUNTER0 (1<<1)
+#define PM_READ_COUNTER1 (1<<2)
+#define PM_READ_COUNTER2 (1<<3)
+#define PM_READ_STATUSVALUE (0<<4)
+#define PM_READ_VALUE       (1<<4)
+#define PM_READ_STATUS      (2<<4)
+
+// Bits for PORT_PS2_CTRLB
+#define PPCB_T2GATE (1<<0)
+#define PPCB_SPKR   (1<<1)
+#define PPCB_T2OUT  (1<<5)
+
+#define PMTIMER_HZ 3579545      // Underlying Hz of the PM Timer
+#define PMTIMER_TO_PIT 3        // Ratio of pmtimer rate to pit rate
+
+u32 TimerKHz VARFSEG;
+u16 TimerPort VARFSEG;
+u8 ShiftTSC VARFSEG;
+
+
+/****************************************************************
+ * Internal timer setup
+ ****************************************************************/
+
+#define CALIBRATE_COUNT 0x800   // Approx 1.7ms
+
+// Calibrate the CPU time-stamp-counter
+static void
+tsctimer_setup(void)
+{
+    // Setup "timer2"
+    u8 orig = inb(PORT_PS2_CTRLB);
+    outb((orig & ~PPCB_SPKR) | PPCB_T2GATE, PORT_PS2_CTRLB);
+    /* binary, mode 0, LSB/MSB, Ch 2 */
+    outb(PM_SEL_TIMER2|PM_ACCESS_WORD|PM_MODE0|PM_CNT_BINARY, PORT_PIT_MODE);
+    /* LSB of ticks */
+    outb(CALIBRATE_COUNT & 0xFF, PORT_PIT_COUNTER2);
+    /* MSB of ticks */
+    outb(CALIBRATE_COUNT >> 8, PORT_PIT_COUNTER2);
+
+    u64 start = rdtscll();
+    while ((inb(PORT_PS2_CTRLB) & PPCB_T2OUT) == 0)
+        ;
+    u64 end = rdtscll();
+
+    // Restore PORT_PS2_CTRLB
+    outb(orig, PORT_PS2_CTRLB);
+
+    // Store calibrated cpu khz.
+    u64 diff = end - start;
+    dprintf(6, "tsc calibrate start=%u end=%u diff=%u\n"
+            , (u32)start, (u32)end, (u32)diff);
+    u64 t = DIV_ROUND_UP(diff * PMTIMER_HZ, CALIBRATE_COUNT);
+    while (t >= (1<<24)) {
+        ShiftTSC++;
+        t = (t + 1) >> 1;
+    }
+    TimerKHz = DIV_ROUND_UP((u32)t, 1000 * PMTIMER_TO_PIT);
+
+    dprintf(1, "CPU Mhz=%u\n", (TimerKHz << ShiftTSC) / 1000);
+}
+
+// Setup internal timers.
+void
+timer_setup(void)
+{
+    if (CONFIG_PMTIMER && TimerPort) {
+        dprintf(3, "pmtimer already configured; will not calibrate TSC\n");
+        return;
+    }
+
+    u32 eax, ebx, ecx, edx, cpuid_features = 0;
+    cpuid(0, &eax, &ebx, &ecx, &edx);
+    if (eax > 0)
+        cpuid(1, &eax, &ebx, &ecx, &cpuid_features);
+
+    if (!(cpuid_features & CPUID_TSC)) {
+        TimerPort = PORT_PIT_COUNTER0;
+        TimerKHz = DIV_ROUND_UP(PMTIMER_HZ, 1000 * PMTIMER_TO_PIT);
+        dprintf(3, "386/486 class CPU. Using TSC emulation\n");
+        return;
+    }
+
+    tsctimer_setup();
+}
+
+void
+pmtimer_setup(u16 ioport)
+{
+    if (!CONFIG_PMTIMER)
+        return;
+    dprintf(1, "Using pmtimer, ioport 0x%x\n", ioport);
+    TimerPort = ioport;
+    TimerKHz = DIV_ROUND_UP(PMTIMER_HZ, 1000);
+}
+
+
+/****************************************************************
+ * Internal timer reading
+ ****************************************************************/
+
+u32 TimerLast VARLOW;
+
+// Add extra high bits to timers that have less than 32bits of precision.
+static u32
+timer_adjust_bits(u32 value, u32 validbits)
+{
+    u32 last = GET_LOW(TimerLast);
+    value = (last & ~validbits) | (value & validbits);
+    if (value < last)
+        value += validbits + 1;
+    SET_LOW(TimerLast, value);
+    return value;
+}
+
+// Sample the current timer value.
+static u32
+timer_read(void)
+{
+    u16 port = GET_GLOBAL(TimerPort);
+    if (!port)
+        // Read from CPU TSC
+        return rdtscll() >> GET_GLOBAL(ShiftTSC);
+    if (CONFIG_PMTIMER && port != PORT_PIT_COUNTER0)
+        // Read from PMTIMER
+        return timer_adjust_bits(inl(port), 0xffffff);
+    // Read from PIT.
+    outb(PM_SEL_READBACK | PM_READ_VALUE | PM_READ_COUNTER0, PORT_PIT_MODE);
+    u16 v = inb(PORT_PIT_COUNTER0) | (inb(PORT_PIT_COUNTER0) << 8);
+    return timer_adjust_bits(v, 0xffff);
+}
+
+// Check if the current time is past a previously calculated end time.
+int
+timer_check(u32 end)
+{
+    return (s32)(timer_read() - end) > 0;
+}
+
+static void
+timer_delay(u32 diff)
+{
+    u32 start = timer_read();
+    u32 end = start + diff;
+    while (!timer_check(end))
+        cpu_relax();
+}
+
+static void
+timer_sleep(u32 diff)
+{
+    u32 start = timer_read();
+    u32 end = start + diff;
+    while (!timer_check(end))
+        yield();
+}
+
+void ndelay(u32 count) {
+    timer_delay(DIV_ROUND_UP(count * GET_GLOBAL(TimerKHz), 1000000));
+}
+void udelay(u32 count) {
+    timer_delay(DIV_ROUND_UP(count * GET_GLOBAL(TimerKHz), 1000));
+}
+void mdelay(u32 count) {
+    timer_delay(count * GET_GLOBAL(TimerKHz));
+}
+
+void nsleep(u32 count) {
+    timer_sleep(DIV_ROUND_UP(count * GET_GLOBAL(TimerKHz), 1000000));
+}
+void usleep(u32 count) {
+    timer_sleep(DIV_ROUND_UP(count * GET_GLOBAL(TimerKHz), 1000));
+}
+void msleep(u32 count) {
+    timer_sleep(count * GET_GLOBAL(TimerKHz));
+}
+
+// Return the TSC value that is 'msecs' time in the future.
+u32
+timer_calc(u32 msecs)
+{
+    return timer_read() + (GET_GLOBAL(TimerKHz) * msecs);
+}
+u32
+timer_calc_usec(u32 usecs)
+{
+    return timer_read() + DIV_ROUND_UP(GET_GLOBAL(TimerKHz) * usecs, 1000);
+}
+
+
+/****************************************************************
+ * PIT setup
+ ****************************************************************/
+
+#define PIT_TICK_INTERVAL 65536 // Default interval for 18.2Hz timer
+
+// Return the number of milliseconds in 'ticks' number of timer irqs.
+u32
+ticks_to_ms(u32 ticks)
+{
+    u32 t = PIT_TICK_INTERVAL * 1000 * PMTIMER_TO_PIT * ticks;
+    return DIV_ROUND_UP(t, PMTIMER_HZ);
+}
+
+// Return the number of timer irqs in 'ms' number of milliseconds.
+u32
+ticks_from_ms(u32 ms)
+{
+    u32 t = DIV_ROUND_UP((u64)ms * PMTIMER_HZ, PIT_TICK_INTERVAL);
+    return DIV_ROUND_UP(t, 1000 * PMTIMER_TO_PIT);
+}
+
+void
+pit_setup(void)
+{
+    // timer0: binary count, 16bit count, mode 2
+    outb(PM_SEL_TIMER0|PM_ACCESS_WORD|PM_MODE2|PM_CNT_BINARY, PORT_PIT_MODE);
+    // maximum count of 0000H = 18.2Hz
+    outb(0x0, PORT_PIT_COUNTER0);
+    outb(0x0, PORT_PIT_COUNTER0);
+}