From 7aa6c9aa96049b741b754b7340ea96a37719de27 Mon Sep 17 00:00:00 2001
From: Anup Patel <anup.patel@wdc.com>
Date: Sat, 24 Jul 2021 10:35:01 +0530
Subject: lib: utils/timer: Simplify MTIMER synchronization
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@wdc.com>
Reviewed-by: Atish Patra <atish.patra@wdc.com>
---
lib/utils/timer/fdt_timer_mtimer.c | 42 +++++++++++++++++++++++++++++++++-----
1 file changed, 37 insertions(+), 5 deletions(-)
(limited to 'lib/utils/timer/fdt_timer_mtimer.c')
diff --git a/lib/utils/timer/fdt_timer_mtimer.c b/lib/utils/timer/fdt_timer_mtimer.c
index 15a36ed..4eafffa 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 +63,42 @@ 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. This is only a temporary strategy
+ * of selecting reference MTIMER device. In future, we might
+ * define an optional DT property or some other mechanism to
+ * help us select the 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;
}
--
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