libsel4platsupport: allow tsc timer to be constructed with previously established frequency

libsel4platsupport/plat_include/pc99/sel4platsupport/plat/timer.h

diff --git a/libsel4platsupport/plat_include/pc99/sel4platsupport/plat/timer.h b/libsel4platsupport/plat_include/pc99/sel4platsupport/plat/timer.h
index 2b44ebf..842e3cb 100644
--- a/libsel4platsupport/plat_include/pc99/sel4platsupport/plat/timer.h
+++ b/libsel4platsupport/plat_include/pc99/sel4platsupport/plat/timer.h
@@ -17,9 +17,21 @@
 /**
  * Get a tsc backed seL4_timer_t;
  *
+ * @param freq frequency of the tsc.
+ * @return NULL on error.
+ */
+seL4_timer_t *sel4platsupport_get_tsc_timer_freq(uint64_t freq);
+
+/**
+ * Get a tsc backed seL4_timer_t;
+ *
+ * Note that measuring the tsc frequency is expensive, so use of this function should be minimal.
+ *
  * @param timeout_timer timer that implements timeouts to calculate the CPU frequency with.
  * @return NULL on error.
  */
+
 seL4_timer_t *sel4platsupport_get_tsc_timer(seL4_timer_t *timeout_timer);
 
+
 #endif /* _SEL4PLATSUPPORT_PLAT_TIMER_H */

libsel4platsupport/src/plat/pc99/timer.c

diff --git a/libsel4platsupport/src/plat/pc99/timer.c b/libsel4platsupport/src/plat/pc99/timer.c
index 658e335..84536bd 100644
--- a/libsel4platsupport/src/plat/pc99/timer.c
+++ b/libsel4platsupport/src/plat/pc99/timer.c
@@ -31,19 +31,50 @@
     return pit;
 }
 
-seL4_timer_t *
-sel4platsupport_get_tsc_timer(seL4_timer_t *timeout_timer)
+static seL4_timer_t *
+finish_get_tsc(seL4_timer_t *seL4_timer, pstimer_t *ps_timer)
 {
-
-    seL4_timer_t *timer = calloc(1, sizeof(seL4_timer_t));
-    if (timer == NULL) {
+    if (ps_timer == NULL) {
+        ZF_LOGE("Failed to init tsc");
+        free(seL4_timer);
         return NULL;
     }
 
-    timer->timer = tsc_get_timer(timeout_timer->timer);
-
-    return timer;
+    seL4_timer->timer = ps_timer;
+    return seL4_timer;
 }
 
+seL4_timer_t *
+sel4platsupport_get_tsc_timer_freq(uint64_t freq)
+{
+    if (freq == 0) {
+        ZF_LOGE("Can't init tsc with 0 freq");
+        return NULL;
+    }
 
+    seL4_timer_t *timer = calloc(1, sizeof(seL4_timer_t));
+    if (timer == NULL) {
+        ZF_LOGE("Failed to allocate timer");
+        return NULL;
+    }
+
+    return finish_get_tsc(timer, tsc_get_timer_with_freq(freq));
+}
+
+seL4_timer_t *
+sel4platsupport_get_tsc_timer(seL4_timer_t *timeout_timer)
+{
+    if (timeout_timer == NULL) {
+        ZF_LOGE("Cannot initialise tsc frequency, timeout timer is NULL");
+        return NULL;
+    }
+
+    seL4_timer_t *timer = calloc(1, sizeof(seL4_timer_t));
+    if (timer == NULL) {
+        ZF_LOGE("Failed to allocate timer");
+        return NULL;
+    }
+
+    return finish_get_tsc(timer, tsc_get_timer(timeout_timer));
+}
 

libsel4platsupport/src/timer_common.c

diff --git a/libsel4platsupport/src/timer_common.c b/libsel4platsupport/src/timer_common.c
index 704c1c8..bb5e649 100644
--- a/libsel4platsupport/src/timer_common.c
+++ b/libsel4platsupport/src/timer_common.c
@@ -91,6 +91,7 @@
 
     /* map in the frame */
     timer_data->vaddr = vspace_map_pages(vspace, &frame_cap, NULL, seL4_AllRights, 1, seL4_PageBits, 0);
+    ZF_LOGV("Mapped timer at %p\n", timer_data->vaddr);
     if (timer_data->vaddr == NULL) {
         LOG_ERROR("Failed to map page at vaddr %p\n", timer_data->vaddr);
         goto error;
@@ -108,6 +109,7 @@
         goto error;
     }
 
+    ZF_LOGV("Timer initialised\n");
     /* success */
     return timer_data;