[PATCH v2 5/5] lib: utils/timer: Simplify MTIMER synchronization
Anup Patel
anup.patel at wdc.com
Sat Aug 7 06:33:22 PDT 2021
We simplify MTIMER synchronization as follows:
1) Detect MTIMER devices with unique (or non-shared) MTIME
register at boot-time
2) Select first MTIMER device with no associated HART as our
reference MTIMER device
3) Only synchronize MTIMER devices with unique (or non-shared)
MTIME register using reference MTIMER device
4) Directly update the MTIME register at time of synchronization
because MTIME is a read/write register.
Signed-off-by: Anup Patel <anup.patel at wdc.com>
---
include/sbi_utils/timer/aclint_mtimer.h | 7 ++-
lib/utils/timer/aclint_mtimer.c | 67 +++++++++++++++----------
lib/utils/timer/fdt_timer_mtimer.c | 39 ++++++++++++--
3 files changed, 80 insertions(+), 33 deletions(-)
diff --git a/include/sbi_utils/timer/aclint_mtimer.h b/include/sbi_utils/timer/aclint_mtimer.h
index fdc46cd..a9fe445 100644
--- a/include/sbi_utils/timer/aclint_mtimer.h
+++ b/include/sbi_utils/timer/aclint_mtimer.h
@@ -31,14 +31,19 @@ struct aclint_mtimer_data {
u32 first_hartid;
u32 hart_count;
bool has_64bit_mmio;
+ bool has_shared_mtime;
/* Private details (initialized and used by ACLINT MTIMER library) */
struct aclint_mtimer_data *time_delta_reference;
unsigned long time_delta_computed;
- u64 time_delta;
u64 (*time_rd)(volatile u64 *addr);
void (*time_wr)(bool timecmp, u64 value, volatile u64 *addr);
};
+void aclint_mtimer_sync(struct aclint_mtimer_data *mt);
+
+void aclint_mtimer_set_reference(struct aclint_mtimer_data *mt,
+ struct aclint_mtimer_data *ref);
+
int aclint_mtimer_warm_init(void);
int aclint_mtimer_cold_init(struct aclint_mtimer_data *mt,
diff --git a/lib/utils/timer/aclint_mtimer.c b/lib/utils/timer/aclint_mtimer.c
index 0e4e846..d612b12 100644
--- a/lib/utils/timer/aclint_mtimer.c
+++ b/lib/utils/timer/aclint_mtimer.c
@@ -57,7 +57,7 @@ static u64 mtimer_value(void)
u64 *time_val = (void *)mt->mtime_addr;
/* Read MTIMER Time Value */
- return mt->time_rd(time_val) + mt->time_delta;
+ return mt->time_rd(time_val);
}
static void mtimer_event_stop(void)
@@ -77,7 +77,7 @@ static void mtimer_event_start(u64 next_event)
u64 *time_cmp = (void *)mt->mtimecmp_addr;
/* Program MTIMER Time Compare */
- mt->time_wr(true, next_event - mt->time_delta,
+ mt->time_wr(true, next_event,
&time_cmp[target_hart - mt->first_hartid]);
}
@@ -88,36 +88,51 @@ static struct sbi_timer_device mtimer = {
.timer_event_stop = mtimer_event_stop
};
+void aclint_mtimer_sync(struct aclint_mtimer_data *mt)
+{
+ u64 v1, v2, mv, delta;
+ u64 *mt_time_val, *ref_time_val;
+ struct aclint_mtimer_data *reference;
+
+ /* Sync-up non-shared MTIME if reference is available */
+ if (mt->has_shared_mtime || !mt->time_delta_reference)
+ return;
+
+ reference = mt->time_delta_reference;
+ mt_time_val = (void *)mt->mtime_addr;
+ ref_time_val = (void *)reference->mtime_addr;
+ if (!atomic_raw_xchg_ulong(&mt->time_delta_computed, 1)) {
+ v1 = mt->time_rd(mt_time_val);
+ mv = reference->time_rd(ref_time_val);
+ v2 = mt->time_rd(mt_time_val);
+ delta = mv - ((v1 / 2) + (v2 / 2));
+ mt->time_wr(false, mt->time_rd(mt_time_val) + delta,
+ mt_time_val);
+ }
+
+}
+
+void aclint_mtimer_set_reference(struct aclint_mtimer_data *mt,
+ struct aclint_mtimer_data *ref)
+{
+ if (!mt || !ref || mt == ref)
+ return;
+
+ mt->time_delta_reference = ref;
+ mt->time_delta_computed = 0;
+}
+
int aclint_mtimer_warm_init(void)
{
- u64 v1, v2, mv;
+ u64 *mt_time_cmp;
u32 target_hart = current_hartid();
- struct aclint_mtimer_data *reference;
- u64 *mt_time_val, *mt_time_cmp, *ref_time_val;
struct aclint_mtimer_data *mt = mtimer_hartid2data[target_hart];
if (!mt)
return SBI_ENODEV;
- /*
- * Compute delta if reference available
- *
- * We deliberately compute time_delta in warm init so that time_delta
- * is computed on a HART which is going to use given MTIMER. We use
- * atomic flag timer_delta_computed to ensure that only one HART does
- * time_delta computation.
- */
- if (mt->time_delta_reference) {
- reference = mt->time_delta_reference;
- mt_time_val = (void *)mt->mtime_addr;
- ref_time_val = (void *)reference->mtime_addr;
- if (!atomic_raw_xchg_ulong(&mt->time_delta_computed, 1)) {
- v1 = mt->time_rd(mt_time_val);
- mv = reference->time_rd(ref_time_val);
- v2 = mt->time_rd(mt_time_val);
- mt->time_delta = mv - ((v1 / 2) + (v2 / 2));
- }
- }
+ /* Sync-up MTIME register */
+ aclint_mtimer_sync(mt);
/* Clear Time Compare */
mt_time_cmp = (void *)mt->mtimecmp_addr;
@@ -173,9 +188,7 @@ int aclint_mtimer_cold_init(struct aclint_mtimer_data *mt,
return SBI_EINVAL;
/* Initialize private data */
- mt->time_delta_reference = reference;
- mt->time_delta_computed = 0;
- mt->time_delta = 0;
+ aclint_mtimer_set_reference(mt, reference);
mt->time_rd = mtimer_time_rd32;
mt->time_wr = mtimer_time_wr32;
diff --git a/lib/utils/timer/fdt_timer_mtimer.c b/lib/utils/timer/fdt_timer_mtimer.c
index 15a36ed..26b5a2a 100644
--- a/lib/utils/timer/fdt_timer_mtimer.c
+++ b/lib/utils/timer/fdt_timer_mtimer.c
@@ -17,19 +17,18 @@
static unsigned long mtimer_count = 0;
static struct aclint_mtimer_data mtimer[MTIMER_MAX_NR];
+static struct aclint_mtimer_data *mt_reference = NULL;
static int timer_mtimer_cold_init(void *fdt, int nodeoff,
const struct fdt_match *match)
{
- int rc;
+ int i, rc;
unsigned long offset, addr[2], size[2];
- struct aclint_mtimer_data *mt, *mtmaster = NULL;
+ struct aclint_mtimer_data *mt;
if (MTIMER_MAX_NR <= mtimer_count)
return SBI_ENOSPC;
mt = &mtimer[mtimer_count];
- if (0 < mtimer_count)
- mtmaster = &mtimer[0];
rc = fdt_parse_aclint_node(fdt, nodeoff, true,
&addr[0], &size[0], &addr[1], &size[1],
@@ -37,6 +36,7 @@ static int timer_mtimer_cold_init(void *fdt, int nodeoff,
if (rc)
return rc;
mt->has_64bit_mmio = true;
+ mt->has_shared_mtime = false;
if (match->data) { /* SiFive CLINT */
/* Set CLINT addresses */
@@ -63,10 +63,39 @@ static int timer_mtimer_cold_init(void *fdt, int nodeoff,
mt->has_64bit_mmio = false;
}
- rc = aclint_mtimer_cold_init(mt, mtmaster);
+ /* Check if MTIMER device has shared MTIME address */
+ mt->has_shared_mtime = false;
+ for (i = 0; i < mtimer_count; i++) {
+ if (mtimer[i].mtime_addr == mt->mtime_addr) {
+ mt->has_shared_mtime = true;
+ break;
+ }
+ }
+
+ /* Initialize the MTIMER device */
+ rc = aclint_mtimer_cold_init(mt, mt_reference);
if (rc)
return rc;
+ /*
+ * Select first MTIMER device with no associated HARTs as
+ * our reference MTIMER device
+ */
+ if (!mt->hart_count && !mt_reference) {
+ mt_reference = mt;
+ /*
+ * Set reference for already propbed MTIMER devices
+ * with non-shared MTIME
+ */
+ for (i = 0; i < mtimer_count; i++)
+ if (!mtimer[i].has_shared_mtime)
+ aclint_mtimer_set_reference(&mtimer[i], mt);
+ }
+
+ /* Explicitly sync-up MTIMER devices not associated with any HARTs */
+ if (!mt->hart_count)
+ aclint_mtimer_sync(mt);
+
mtimer_count++;
return 0;
}
--
2.25.1
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