[PATCH ARM v8 1/4] mini-os: arm: time

[Thomas Leonard <talex5@gmail.com>]

Based on an initial patch by Karim Raslan.

Signed-off-by: Karim Allah Ahmed <karim.allah.ahmed@gmail.com>
Signed-off-by: Thomas Leonard <talex5@gmail.com>

---

Changes since v7:

Addressed Ian Campbell's comments:

- removed unnecessary isb
- removed some debug comments
- simplified some of the asm calls
---
 extras/mini-os/arch/arm/time.c | 136 +++++++++++++++++++++++++++++++++++++++++
 1 file changed, 136 insertions(+)
 create mode 100644 extras/mini-os/arch/arm/time.c

diff --git a/extras/mini-os/arch/arm/time.c b/extras/mini-os/arch/arm/time.c
new file mode 100644
index 0000000..a088981
--- /dev/null
+++ b/extras/mini-os/arch/arm/time.c
@@ -0,0 +1,136 @@
+#include <mini-os/os.h>
+#include <mini-os/hypervisor.h>
+#include <mini-os/events.h>
+#include <mini-os/traps.h>
+#include <mini-os/types.h>
+#include <mini-os/time.h>
+#include <mini-os/lib.h>
+
+//#define VTIMER_DEBUG
+#ifdef VTIMER_DEBUG
+#define DEBUG(_f, _a...) \
+    printk("MINI_OS(file=vtimer.c, line=%d) " _f , __LINE__, ## _a)
+#else
+#define DEBUG(_f, _a...)    ((void)0)
+#endif
+
+/************************************************************************
+ * Time functions
+ *************************************************************************/
+
+static uint64_t cntvct_at_init;
+static uint32_t counter_freq;
+
+/* Compute with 96 bit intermediate result: (a*b)/c */
+uint64_t muldiv64(uint64_t a, uint32_t b, uint32_t c)
+{
+    union {
+        uint64_t ll;
+        struct {
+            uint32_t low, high;
+        } l;
+    } u, res;
+    uint64_t rl, rh;
+
+    u.ll = a;
+    rl = (uint64_t)u.l.low * (uint64_t)b;
+    rh = (uint64_t)u.l.high * (uint64_t)b;
+    rh += (rl >> 32);
+    res.l.high = rh / c;
+    res.l.low = (((rh % c) << 32) + (rl & 0xffffffff)) / c;
+    return res.ll;
+}
+
+static inline s_time_t ticks_to_ns(uint64_t ticks)
+{
+    return muldiv64(ticks, SECONDS(1), counter_freq);
+}
+
+static inline uint64_t ns_to_ticks(s_time_t ns)
+{
+    return muldiv64(ns, counter_freq, SECONDS(1));
+}
+
+/* Wall-clock time is not currently available on ARM, so this is always zero for now:
+ * http://wiki.xenproject.org/wiki/Xen_ARM_TODO#Expose_Wallclock_time_to_guests
+ */
+static struct timespec shadow_ts;
+
+static inline uint64_t read_virtual_count(void)
+{
+    uint32_t c_lo, c_hi;
+    __asm__ __volatile__("mrrc p15, 1, %0, %1, c14":"=r"(c_lo), "=r"(c_hi));
+    return (((uint64_t) c_hi) << 32) + c_lo;
+}
+
+/* monotonic_clock(): returns # of nanoseconds passed since time_init()
+ *        Note: This function is required to return accurate
+ *        time even in the absence of multiple timer ticks.
+ */
+uint64_t monotonic_clock(void)
+{
+    return ticks_to_ns(read_virtual_count() - cntvct_at_init);
+}
+
+int gettimeofday(struct timeval *tv, void *tz)
+{
+    uint64_t nsec = monotonic_clock();
+    nsec += shadow_ts.tv_nsec;
+
+    tv->tv_sec = shadow_ts.tv_sec;
+    tv->tv_sec += NSEC_TO_SEC(nsec);
+    tv->tv_usec = NSEC_TO_USEC(nsec % 1000000000UL);
+
+    return 0;
+}
+
+/* Set the timer and mask. */
+void write_timer_ctl(uint32_t value) {
+    __asm__ __volatile__(
+            "mcr p15, 0, %0, c14, c3, 1\n"
+            "isb"::"r"(value));
+}
+
+void set_vtimer_compare(uint64_t value) {
+    DEBUG("New CompareValue : %llx\n", value);
+
+    __asm__ __volatile__("mcrr p15, 3, %0, %H0, c14"
+            ::"r"(value));
+
+    /* Enable timer and unmask the output signal */
+    write_timer_ctl(1);
+}
+
+void unset_vtimer_compare(void) {
+    /* Disable timer and mask the output signal */
+    write_timer_ctl(2);
+}
+
+void block_domain(s_time_t until)
+{
+    uint64_t until_count = ns_to_ticks(until) + cntvct_at_init;
+    ASSERT(irqs_disabled());
+    if (read_virtual_count() < until_count)
+    {
+        set_vtimer_compare(until_count);
+        __asm__ __volatile__("wfi");
+        unset_vtimer_compare();
+
+        /* Give the IRQ handler a chance to handle whatever woke us up. */
+        local_irq_enable();
+        local_irq_disable();
+    }
+}
+
+void init_time(void)
+{
+    printk("Initialising timer interface\n");
+
+    __asm__ __volatile__("mrc p15, 0, %0, c14, c0, 0":"=r"(counter_freq));
+    cntvct_at_init = read_virtual_count();
+    printk("Virtual Count register is %llx, freq = %d Hz\n", cntvct_at_init, counter_freq);
+}
+
+void fini_time(void)
+{
+}
-- 
2.1.1