From 7091ca455c0333113f0ffbadc2de292cf986d7f7 Mon Sep 17 00:00:00 2001
From: Rodrigo Arias Mallo <rodarima@gmail.com>
Date: Wed, 21 Aug 2024 12:28:17 +0200
Subject: [PATCH] Enable timer from supervisor

---
 JOURNAL.md              |  2 +-
 opensbi-test-plic.patch | 20 +++++++++++---------
 2 files changed, 12 insertions(+), 10 deletions(-)

diff --git a/JOURNAL.md b/JOURNAL.md
index c73db79..110e04b 100644
--- a/JOURNAL.md
+++ b/JOURNAL.md
@@ -3463,7 +3463,7 @@ Let's set the stvec to zero, so it causes a machine exception.
 
 # 2024-08-21
 
-I tried with the new bitstream (ox_u55c_46619ef4.bit) setting the stvec to zero
+I tried with the new bitstream (`ox_u55c_46619ef4.bit`) setting the stvec to zero
 and I can see the OpenSBI handler stopping, probably due to the jump to zero
 address:
 
diff --git a/opensbi-test-plic.patch b/opensbi-test-plic.patch
index 8f3df08..f676341 100644
--- a/opensbi-test-plic.patch
+++ b/opensbi-test-plic.patch
@@ -1,5 +1,5 @@
 diff --git a/lib/sbi/sbi_irqchip.c b/lib/sbi/sbi_irqchip.c
-index 0ae604a..54449c7 100644
+index 0ae604a..c446e60 100644
 --- a/lib/sbi/sbi_irqchip.c
 +++ b/lib/sbi/sbi_irqchip.c
 @@ -9,6 +9,9 @@
@@ -25,7 +25,7 @@ index 0ae604a..54449c7 100644
  
  	return 0;
  }
-@@ -47,8 +52,161 @@ void sbi_irqchip_exit(struct sbi_scratch *scratch)
+@@ -47,8 +52,163 @@ void sbi_irqchip_exit(struct sbi_scratch *scratch)
  {
  	const struct sbi_platform *plat = sbi_platform_ptr(scratch);
  
@@ -61,6 +61,10 @@ index 0ae604a..54449c7 100644
 +#define MSTATUS_MPP_MASK (3 << 11)
 +#define MSTATUS_MPP_SUPERVISOR (1 << 11)
 +
++static volatile unsigned long *mtime    = (unsigned long *)(AUX_TIMER_BASE + MTIME_OFFSET);
++static volatile unsigned long *mtimecmp = (unsigned long *)(AUX_TIMER_BASE + MTIMECMP_OFFSET);
++
++
 +static void dumpregs(int machine)
 +{
 +	char *prefix = "\t";
@@ -108,6 +112,11 @@ index 0ae604a..54449c7 100644
 +{
 +	sbi_printf("Hello from supervisor\n");
 +	dumpregs(0);
++
++	/* Enable timer interrupt */
++	*mtimecmp = *mtime + 10000;
++
++	sbi_printf("Timer alarm programmed\n");
 +	sbi_printf("Waiting for interrupt...\n");
 +	int i = 0;
 +	char *s = "-\\|/";
@@ -129,9 +138,6 @@ index 0ae604a..54449c7 100644
 +{
 +	sbi_printf("--- TESTING PLIC ---\n");
 +
-+	volatile unsigned long *mtime    = (unsigned long *)(AUX_TIMER_BASE + MTIME_OFFSET);
-+	volatile unsigned long *mtimecmp = (unsigned long *)(AUX_TIMER_BASE + MTIMECMP_OFFSET);
-+
 +	/* Disable auxiliar timer interrupt */
 +	*mtimecmp = 0xffffffffUL;
 +	sbi_printf("Timer interrupt disabled\n");
@@ -174,10 +180,6 @@ index 0ae604a..54449c7 100644
 +	//sbi_printf("Enabling MIE in MSTATUS register\n");
 +	//csr_set(CSR_MSTATUS, MSTATUS_MIE); /* Needed? */
 +
-+	/* Enable timer interrupt */
-+	*mtimecmp = *mtime + 10000;
-+
-+	sbi_printf("Timer alarm programmed\n");
 +	sbi_printf("Switching to supervisor\n");
 +
 +	dumpregs(1);