From 6576a92ba57266dcf551854ef665c8250e6d1a07 Mon Sep 17 00:00:00 2001
From: Rodrigo Arias Mallo <rodrigo.arias@bsc.es>
Date: Fri, 12 Jul 2024 13:47:01 +0200
Subject: [PATCH] Debug timer_mtimer_cold_init() in OpenSBI

---
 JOURNAL.md                | 51 +++++++++++++++++++++++++++++++++++
 opensbi-timer-debug.patch | 57 +++++++++++++++++++++++++++++++++++++++
 2 files changed, 108 insertions(+)

diff --git a/JOURNAL.md b/JOURNAL.md
index a8c1ddd..0c888da 100644
--- a/JOURNAL.md
+++ b/JOURNAL.md
@@ -1623,3 +1623,54 @@ These G's must be coming from the bootrom.
 
 So let's go back to the generic platform and place some `printf()` calls to
 determine where it is failing.
+
+    OpenSBI v1.5
+       ____                    _____ ____ _____
+      / __ \                  / ____|  _ \_   _|
+     | |  | |_ __   ___ _ __ | (___ | |_) || |
+     | |  | | '_ \ / _ \ '_ \ \___ \|  _ < | |
+     | |__| | |_) |  __/ | | |____) | |_) || |_
+      \____/| .__/ \___|_| |_|_____/|____/_____|
+            | |
+            |_|
+
+    sbi_timer_init: begins
+    sbi_timer_init: got Zicntr extension
+    fdt_timer_cold_init: pos = 0
+    fdt_timer_cold_init: got match, name = riscv,clint0
+    fdt_timer_cold_init: enabled
+    fdt_timer_cold_init: drc->cold_init = -3
+    fdt_timer_init: fdt_timer_cold_init failed (-3)
+    sbi_platform_timer: sbi_platform_timer_init failed (-3)
+    init_coldboot: timer init failed (error -3)
+
+Okay, now we can see where it failed. I wonder why aren't these messages enabled
+by default. I'll guess this is the `timer_mtimer_cold_init()` function, so let's
+add some more instrumentation there.
+
+It seems that SiFive timer has a very long weird offset:
+
+    if (is_clint) { /* SiFive CLINT */
+            /* Set CLINT addresses */
+            mt->mtimecmp_addr = addr[0] + ACLINT_DEFAULT_MTIMECMP_OFFSET;
+            mt->mtimecmp_size = ACLINT_DEFAULT_MTIMECMP_SIZE;
+            if (!quirks->clint_without_mtime) {
+                    mt->mtime_addr = addr[0] + ACLINT_DEFAULT_MTIME_OFFSET;
+                    mt->mtime_size = size[0] - mt->mtimecmp_size;
+                    /* Adjust MTIMER address and size for CLINT device */
+                    mt->mtime_addr += quirks->clint_mtime_offset;
+                    mt->mtime_size -= quirks->clint_mtime_offset;
+            } else {
+                    mt->mtime_addr = mt->mtime_size = 0;
+            }
+            mt->mtimecmp_addr += quirks->clint_mtime_offset;
+    } else { /* RISC-V ACLINT MTIMER */
+            /* Set ACLINT MTIMER addresses */
+            mt->mtime_addr = addr[0];
+            mt->mtime_size = size[0];
+            mt->mtimecmp_addr = addr[1];
+            mt->mtimecmp_size = size[1];
+    }
+
+We may want to use the ACLINT timer instead. Let's first see where the addresses
+lay in memory, and then use that to verify we change it to 0x0 and 0x8.
diff --git a/opensbi-timer-debug.patch b/opensbi-timer-debug.patch
index 93e2df1..f2155f2 100644
--- a/opensbi-timer-debug.patch
+++ b/opensbi-timer-debug.patch
@@ -98,3 +98,60 @@ index f468730..db20526 100644
 +
 +	return rc;
  }
+diff --git a/lib/utils/timer/fdt_timer_mtimer.c b/lib/utils/timer/fdt_timer_mtimer.c
+index 9e27e3a..fba48ca 100644
+--- a/lib/utils/timer/fdt_timer_mtimer.c
++++ b/lib/utils/timer/fdt_timer_mtimer.c
+@@ -8,6 +8,7 @@
+  */
+ 
+ #include <libfdt.h>
++#include <sbi/sbi_console.h>
+ #include <sbi/sbi_error.h>
+ #include <sbi/sbi_heap.h>
+ #include <sbi/sbi_list.h>
+@@ -33,6 +34,7 @@ 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;
+ 	unsigned long addr[2], size[2];
+ 	struct timer_mtimer_node *mtn, *n;
+@@ -40,6 +42,8 @@ static int timer_mtimer_cold_init(void *fdt, int nodeoff,
+ 	const struct timer_mtimer_quirks *quirks = match->data;
+ 	bool is_clint = quirks && quirks->is_clint;
+ 
++	sbi_printf("timer_mtimer_cold_init: begins, is_clint = %d\n", (int) is_clint);
++
+ 	mtn = sbi_zalloc(sizeof(*mtn));
+ 	if (!mtn)
+ 		return SBI_ENOMEM;
+@@ -49,6 +53,7 @@ static int timer_mtimer_cold_init(void *fdt, int nodeoff,
+ 				   &addr[0], &size[0], &addr[1], &size[1],
+ 				   &mt->first_hartid, &mt->hart_count);
+ 	if (rc) {
++		sbi_printf("timer_mtimer_cold_init: fdt_parse_aclint_node failed (%d)\n", rc);
+ 		sbi_free(mtn);
+ 		return rc;
+ 	}
+@@ -57,6 +62,7 @@ static int timer_mtimer_cold_init(void *fdt, int nodeoff,
+ 
+ 	rc = fdt_parse_timebase_frequency(fdt, &mt->mtime_freq);
+ 	if (rc) {
++		sbi_printf("timer_mtimer_cold_init: fdt_parse_timebase_frequency failed (%d)\n", rc);
+ 		sbi_free(mtn);
+ 		return rc;
+ 	}
+@@ -83,6 +89,11 @@ static int timer_mtimer_cold_init(void *fdt, int nodeoff,
+ 		mt->mtimecmp_size = size[1];
+ 	}
+ 
++	sbi_printf("timer_mtimer_cold_init: mtime_addr = 0x%08lx\n", mt->mtime_addr);
++	sbi_printf("timer_mtimer_cold_init: mtime_size = 0x%08lx\n", mt->mtime_size);
++	sbi_printf("timer_mtimer_cold_init: mtime_addr = 0x%08lx\n", mt->mtimecmp_addr);
++	sbi_printf("timer_mtimer_cold_init: mtime_addr = 0x%08lx\n", mt->mtimecmp_size);
++
+ 	/* Apply additional quirks */
+ 	if (quirks) {
+ 		mt->has_64bit_mmio = quirks->has_64bit_mmio;