lib: Introduce sbi_dprintf() API

This patch introduces new sbi_dprintf() API for runtime debug
prints. The sbi_dprintf() will print to console for a given
HART only when SBI_SCRATCH_DEBUG_PRINTS option in enabled in
sbi_scratch for this HART.

We can now add debug prints using sbi_dprintf() at important
places in OpenSBI sources. These debug prints will only show
up when previous booting stage or compile time parameter sets
the SBI_SCRATCH_DEBUG_PRINTS option in scratch space.

Signed-off-by: Anup Patel <anup.patel@wdc.com>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>

include/sbi/sbi_console.h

@@ -31,6 +31,10 @@ int __printf(3, 4) sbi_snprintf(char *out, u32 out_sz, const char *format, ...);
 int __printf(1, 2) sbi_printf(const char *format, ...);
 
 struct sbi_scratch;
+
+int __printf(2, 3) sbi_dprintf(struct sbi_scratch *scratch,
+			       const char *format, ...);
+
 int sbi_console_init(struct sbi_scratch *scratch);
 
 #endif

include/sbi/sbi_scratch.h

@@ -74,6 +74,8 @@ struct sbi_scratch {
 enum sbi_scratch_options {
 	/** Disable prints during boot */
 	SBI_SCRATCH_NO_BOOT_PRINTS = (1 << 0),
+	/** Enable runtime debug prints */
+	SBI_SCRATCH_DEBUG_PRINTS = (1 << 1),
 };
 
 /** Get pointer to sbi_scratch for current HART */

lib/sbi/sbi_console.c

@@ -375,6 +375,19 @@ int sbi_printf(const char *format, ...)
 	return retval;
 }
 
+int sbi_dprintf(struct sbi_scratch *scratch, const char *format, ...)
+{
+	va_list args;
+	int retval = 0;
+
+	va_start(args, format);
+	if (scratch->options & SBI_SCRATCH_DEBUG_PRINTS)
+		retval = print(NULL, NULL, format, args);
+	va_end(args);
+
+	return retval;
+}
+
 int sbi_console_init(struct sbi_scratch *scratch)
 {
 	console_plat = sbi_platform_ptr(scratch);