evl/clock: make default gravity a per-arch setting

Signed-off-by: Philippe Gerum <rpm@xenomai.org>

arch/arm/include/asm/evl/calibration.h

+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _EVL_ARM_ASM_CALIBRATION_H
+#define _EVL_ARM_ASM_CALIBRATION_H
+
+#include <linux/kconfig.h>
+
+static inline unsigned int evl_get_default_clock_gravity(void)
+{
+	/* Reasonable default for many armv7-based systems. */
+	return IS_ENABLED(CONFIG_SMP) ? 6000 : 3000;
+}
+
+#endif /* !_EVL_ARM_ASM_CALIBRATION_H */

arch/arm64/include/asm/evl/calibration.h

+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _EVL_ARM64_ASM_CALIBRATION_H
+#define _EVL_ARM64_ASM_CALIBRATION_H
+
+#include <linux/kconfig.h>
+
+static inline unsigned int evl_get_default_clock_gravity(void)
+{
+	return 3000;
+}
+
+#endif /* !_EVL_ARM64_ASM_CALIBRATION_H */

arch/x86/include/asm/evl/calibration.h

+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _EVL_X86_ASM_CALIBRATION_H
+#define _EVL_X86_ASM_CALIBRATION_H
+
+#include <linux/kconfig.h>
+
+static inline unsigned int evl_get_default_clock_gravity(void)
+{
+	return 3000;
+}
+
+#endif /* !_EVL_X86_ASM_CALIBRATION_H */

kernel/evl/clock.c

@@ -33,6 +33,7 @@
 #include <evl/file.h>
 #include <evl/irq.h>
 #include <evl/uaccess.h>
+#include <asm/evl/calibration.h>
 #include <uapi/evl/factory.h>
 #include <uapi/evl/clock.h>
 #include <trace/events/evl.h>
@@ -1029,11 +1030,12 @@ static int set_coreclk_gravity(struct evl_clock *clock,
 
 static void get_default_gravity(struct evl_clock_gravity *p)
 {
-	unsigned int ulat = 3000; /* ns, decent default. */
+	unsigned int ulat = CONFIG_EVL_LATENCY_USER; /* ns */
+
+	if (!ulat)
+		/* If not specified, pick a reasonable default. */
+		ulat = evl_get_default_clock_gravity();
 
-#if CONFIG_EVL_LATENCY_USER != 0
-	ulat = CONFIG_EVL_LATENCY_USER;
-#endif
 	p->user = ulat;
 	p->kernel = CONFIG_EVL_LATENCY_KERNEL;
 	p->irq = CONFIG_EVL_LATENCY_IRQ;