[coreboot-gerrit] [S] Change in coreboot[main]: Add weak function for SMP hart count

[Maximilian Brune (Code Review)]

Attention is currently required from: Philipp Hug, ron minnich.

Maximilian Brune has uploaded this change for review. ( https://review.coreboot.org/c/coreboot/+/81082?usp=email )

Change subject: Add weak function for SMP hart count
......................................................................

Add weak function for SMP hart count

Signed-off-by: Maximilian Brune 
Change-Id: Icc53185991fed4dbed032a52e51ff71d085ad587
---
M src/arch/riscv/include/arch/smp/smp.h
M src/arch/riscv/smp.c
2 files changed, 16 insertions(+), 4 deletions(-)

git pull ssh://review.coreboot.org:29418/coreboot refs/changes/82/81082/1

diff --git a/src/arch/riscv/include/arch/smp/smp.h b/src/arch/riscv/include/arch/smp/smp.h
index 9d3ae5f..758c4de 100644
--- a/src/arch/riscv/include/arch/smp/smp.h
+++ b/src/arch/riscv/include/arch/smp/smp.h
@@ -3,6 +3,8 @@
 #ifndef _RISCV_SMP_H
 #define _RISCV_SMP_H

+unsigned int smp_get_hart_count(void);
+
 /*
  * This function is used to pause smp. Only the hart with hartid equal
  * to working_hartid can be returned from smp_pause, other harts will
diff --git a/src/arch/riscv/smp.c b/src/arch/riscv/smp.c
index 0a93763..6ecfbc5 100644
--- a/src/arch/riscv/smp.c
+++ b/src/arch/riscv/smp.c
@@ -6,6 +6,12 @@
 #include <arch/smp/atomic.h>
 #include <console/console.h>
 #include <mcall.h>
+#include <assert.h>
+
+__weak unsigned int smp_get_hart_count(void)
+{
+	return CONFIG_MAX_CPUS;
+}

void smp_pause(int working_hartid)
 {
@@ -38,10 +44,13 @@
    	atomic_set(&SYNCB, 0);
    	atomic_set(&SYNCA, 0x01234567);

-		/* waiting for other Hart to enter the halt */
+		int hart_count = smp_get_hart_count();
+		/* waiting for other Hart to enter the halt
+		 * use a poor mans timeout to not wait indefinitiely
+		 */
    	do {
    		barrier();
-		} while (atomic_read(&SYNCB) + 1 < CONFIG_MAX_CPUS);
+		} while (atomic_read(&SYNCB) + 1 < hart_count);

/* initialize for the next call */
    	atomic_set(&SYNCA, 0);
@@ -54,16 +63,17 @@
 void smp_resume(void (*fn)(void *), void *arg)
 {
    int hartid = read_csr(mhartid);
+	int hart_count = smp_get_hart_count();

if (fn == NULL)
    	die("must pass a non-null function pointer\n");

-	for (int i = 0; i < CONFIG_MAX_CPUS; i++) {
+	for (int i = 0; i < hart_count; i++) {
    	OTHER_HLS(i)->entry.fn = fn;
    	OTHER_HLS(i)->entry.arg = arg;
    }

-	for (int i = 0; i < CONFIG_MAX_CPUS; i++)
+	for (int i = 0; i < hart_count; i++)
    	if (i != hartid)
    		set_msip(i, 1);