powerpc/powernv: Support for OPAL console

This adds a udbg and an hvc console backend for supporting a console
using the OPAL console interfaces.

On OPAL v1 we have hvc0 mapped to whatever console the system was
configured for (network or hvsi serial port) via the service
processor.

On OPAL v2 we have hvcN mapped to the Nth console provided by OPAL
which generally corresponds to:

	hvc0 : network console (raw protocol)
	hvc1 : serial port S1 (hvsi)
	hvc2 : serial port S2 (hvsi)

Note: At this point, early debug console only works with OPAL v1
and shouldn't be enabled in a normal kernel.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

2 files changed, 26 insertions, 19 deletions

diff --git a/arch/powerpc/platforms/powernv/opal.c b/arch/powerpc/platforms/powernv/opal.c
index 8d5510784cc..7887733b9b3 100644
--- a/arch/powerpc/platforms/powernv/opal.c
+++ b/arch/powerpc/platforms/powernv/opal.c
@@ -67,7 +67,7 @@ int opal_get_chars(uint32_t vtermno, char *buf, int count)
 	u64 evt;
 
 	if (!opal.entry)
-		return 0;
+		return -ENODEV;
 	opal_poll_events(&evt);
 	if ((evt & OPAL_EVENT_CONSOLE_INPUT) == 0)
 		return 0;
@@ -81,31 +81,38 @@ int opal_get_chars(uint32_t vtermno, char *buf, int count)
 int opal_put_chars(uint32_t vtermno, const char *data, int total_len)
 {
 	int written = 0;
-	s64 len, rc = OPAL_BUSY;
+	s64 len, rc;
 	unsigned long flags;
 	u64 evt;
 
 	if (!opal.entry)
-		return 0;
+		return -ENODEV;
 
 	/* We want put_chars to be atomic to avoid mangling of hvsi
 	 * packets. To do that, we first test for room and return
-	 * -EAGAIN if there isn't enough
+	 * -EAGAIN if there isn't enough.
+	 *
+	 * Unfortunately, opal_console_write_buffer_space() doesn't
+	 * appear to work on opal v1, so we just assume there is
+	 * enough room and be done with it
 	 */
 	spin_lock_irqsave(&opal_write_lock, flags);
-	rc = opal_console_write_buffer_space(vtermno, &len);
-	if (rc || len < total_len) {
-		spin_unlock_irqrestore(&opal_write_lock, flags);
-		/* Closed -> drop characters */
-		if (rc)
-			return total_len;
-		opal_poll_events(&evt);
-		return -EAGAIN;
+	if (firmware_has_feature(FW_FEATURE_OPALv2)) {
+		rc = opal_console_write_buffer_space(vtermno, &len);
+		if (rc || len < total_len) {
+			spin_unlock_irqrestore(&opal_write_lock, flags);
+			/* Closed -> drop characters */
+			if (rc)
+				return total_len;
+			opal_poll_events(&evt);
+			return -EAGAIN;
+		}
 	}
 
 	/* We still try to handle partial completions, though they
 	 * should no longer happen.
 	 */
+	rc = OPAL_BUSY;
 	while(total_len > 0 && (rc == OPAL_BUSY ||
 				rc == OPAL_BUSY_EVENT || rc == OPAL_SUCCESS)) {
 		len = total_len;
diff --git a/arch/powerpc/platforms/powernv/setup.c b/arch/powerpc/platforms/powernv/setup.c
index b6e5ff85cc6..07ba1ecd180 100644
--- a/arch/powerpc/platforms/powernv/setup.c
+++ b/arch/powerpc/platforms/powernv/setup.c
@@ -29,17 +29,12 @@
 #include <asm/machdep.h>
 #include <asm/firmware.h>
 #include <asm/xics.h>
+#include <asm/opal.h>
 
 #include "powernv.h"
 
 static void __init pnv_setup_arch(void)
 {
-	/* Force console to hvc for now until we have sorted out the
-	 * real console situation for the platform. This will make
-	 * hvc_udbg work at least.
-	 */
-	add_preferred_console("hvc", 0, NULL);
-
 	/* Initialize SMP */
 	pnv_smp_init();
 
@@ -55,7 +50,12 @@ static void __init pnv_setup_arch(void)
 
 static void __init pnv_init_early(void)
 {
-	/* XXX IOMMU */
+#ifdef CONFIG_HVC_OPAL
+	if (firmware_has_feature(FW_FEATURE_OPAL))
+		hvc_opal_init_early();
+	else
+#endif
+		add_preferred_console("hvc", 0, NULL);
 }
 
 static void __init pnv_init_IRQ(void)