Add timer debug patch for OpenSBI

JOURNAL.md

@@ -1614,3 +1614,12 @@ different branch, but "control" is never matched there.
 Still failing, the problem must be somewhere else.
 
 Let's try with openpiton configuration instead.
+
+Doesn't even start the UART:
+
+    GGGGGGGGG
+
+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.

lagarto-ox.nix

@@ -310,7 +310,7 @@
       };
       #NIX_DEBUG=5;
       makeFlags = [
-        "PLATFORM=fpga/openpiton"
+        "PLATFORM=generic"
         #"CONFIG_SBI_ECALL_RFENCE=n"
         #"PLATFORM_RISCV_ISA=rv64imafd" # No compressed instructions
         #"PLATFORM_RISCV_ISA=rv64g" # No compressed instructions
@@ -318,7 +318,10 @@
         "FW_PAYLOAD_PATH=${final.uboot}/u-boot-nodtb.bin"
         "FW_FDT_PATH=${final.ox-dtb}"
       ];
-      #patches = [ ./ox-alveo-platform-plic.patch ];
+      patches = [
+        ./opensbi-timer-debug.patch
+        #./ox-alveo-platform-plic.patch
+      ];
     });
 #    opensbi = prev.opensbi.overrideAttrs (old: {
 #      #NIX_DEBUG=5;

opensbi-timer-debug.patch

@@ -0,0 +1,100 @@
+diff --git a/lib/sbi/sbi_timer.c b/lib/sbi/sbi_timer.c
+index 7b618de..65e42b0 100644
+--- a/lib/sbi/sbi_timer.c
++++ b/lib/sbi/sbi_timer.c
+@@ -183,13 +183,17 @@ int sbi_timer_init(struct sbi_scratch *scratch, bool cold_boot)
+ 	u64 *time_delta;
+ 	const struct sbi_platform *plat = sbi_platform_ptr(scratch);
+ 
++	sbi_printf("sbi_timer_init: begins\n");
++
+ 	if (cold_boot) {
+ 		time_delta_off = sbi_scratch_alloc_offset(sizeof(*time_delta));
+ 		if (!time_delta_off)
+ 			return SBI_ENOMEM;
+ 
+-		if (sbi_hart_has_extension(scratch, SBI_HART_EXT_ZICNTR))
++		if (sbi_hart_has_extension(scratch, SBI_HART_EXT_ZICNTR)) {
++			sbi_printf("sbi_timer_init: got Zicntr extension\n");
+ 			get_time_val = get_ticks;
++		}
+ 	} else {
+ 		if (!time_delta_off)
+ 			return SBI_ENOMEM;
+@@ -198,7 +202,10 @@ int sbi_timer_init(struct sbi_scratch *scratch, bool cold_boot)
+ 	time_delta = sbi_scratch_offset_ptr(scratch, time_delta_off);
+ 	*time_delta = 0;
+ 
+-	return sbi_platform_timer_init(plat, cold_boot);
++	int rc = sbi_platform_timer_init(plat, cold_boot);
++	if (rc)
++		sbi_printf("sbi_platform_timer: sbi_platform_timer_init failed (%d)\n", rc);
++	return rc;
+ }
+ 
+ void sbi_timer_exit(struct sbi_scratch *scratch)
+diff --git a/lib/utils/timer/fdt_timer.c b/lib/utils/timer/fdt_timer.c
+index f468730..db20526 100644
+--- a/lib/utils/timer/fdt_timer.c
++++ b/lib/utils/timer/fdt_timer.c
+@@ -7,6 +7,7 @@
+  *   Anup Patel <anup.patel@wdc.com>
+  */
+ 
++#include <sbi/sbi_console.h>
+ #include <sbi/sbi_error.h>
+ #include <sbi/sbi_scratch.h>
+ #include <sbi_utils/fdt/fdt_helper.h>
+@@ -39,19 +40,26 @@ static int fdt_timer_cold_init(void)
+ 	void *fdt = fdt_get_address();
+ 
+ 	for (pos = 0; pos < fdt_timer_drivers_size; pos++) {
++		sbi_printf("fdt_timer_cold_init: pos = %d\n", pos);
+ 		drv = fdt_timer_drivers[pos];
+ 
+ 		noff = -1;
+ 		while ((noff = fdt_find_match(fdt, noff,
+ 					drv->match_table, &match)) >= 0) {
++
++			sbi_printf("fdt_timer_cold_init: got match, name = %s\n", match->compatible);
+ 			if (!fdt_node_is_enabled(fdt, noff))
+ 				continue;
+ 
++			sbi_printf("fdt_timer_cold_init: enabled\n");
++
+ 			/* drv->cold_init must not be NULL */
+ 			if (drv->cold_init == NULL)
+ 				return SBI_EFAIL;
+ 
+ 			rc = drv->cold_init(fdt, noff, match);
++			sbi_printf("fdt_timer_cold_init: drc->cold_init = %d\n", rc);
++
+ 			if (rc == SBI_ENODEV)
+ 				continue;
+ 			if (rc)
+@@ -69,6 +77,7 @@ static int fdt_timer_cold_init(void)
+ 	 * We can't fail here since systems with Sstc might not provide
+ 	 * mtimer/clint DT node in the device tree.
+ 	 */
++	sbi_printf("fdt_timer_cold_init: returns 0\n");
+ 	return 0;
+ }
+ 
+@@ -78,9 +87,15 @@ int fdt_timer_init(bool cold_boot)
+ 
+ 	if (cold_boot) {
+ 		rc = fdt_timer_cold_init();
+-		if (rc)
++		if (rc) {
++			sbi_printf("fdt_timer_init: fdt_timer_cold_init failed (%d)\n", rc);
+ 			return rc;
++		}
+ 	}
+ 
+-	return fdt_timer_warm_init();
++	rc = fdt_timer_warm_init();
++	if (rc)
++		sbi_printf("fdt_timer_init: fdt_timer_warm_init failed (%d)\n", rc);
++
++	return rc;
+ }