[Pdbg] [PATCH] src/main.c: Add detection of host type for kernel backend

[Alistair Popple]

Signed-off-by: Alistair Popple <alistair at popple.id.au>
---
 src/main.c | 40 ++++++++++++++++++++++++++++++++++++++--
 1 file changed, 38 insertions(+), 2 deletions(-)

diff --git a/src/main.c b/src/main.c
index 883e892..79f67a5 100644
--- a/src/main.c
+++ b/src/main.c
@@ -52,6 +52,8 @@
 #include "p9r-fsi.dt.h"
 #include "p9z-fsi.dt.h"
 #include "p9-kernel.dt.h"
+
+#define FSI_CFAM_ID "/sys/devices/platform/gpio-fsi/fsi0/slave at 00:00/cfam_id"
 #endif
 
 #ifdef TARGET_PPC
@@ -59,6 +61,10 @@
 #include "p9-host.dt.h"
 #endif
 
+#define CHIP_ID_P8  0xea
+#define CHIP_ID_P9  0xd1
+#define CHIP_ID_P8P 0xd3
+
 #define THREADS_PER_CORE	8
 
 static enum backend backend = KERNEL;
@@ -629,9 +635,39 @@ static int target_selection(void)
 
 	case KERNEL:
 		if (device_node == NULL) {
-			PR_ERROR("kernel backend requires a device type\n");
-			return -1;
+			FILE *cfam_id_file;
+
+			/* Try and determine the correct device type */
+			cfam_id_file = fopen(FSI_CFAM_ID, "r");
+			if (cfam_id_file) {
+				uint32_t cfam_id = 0;
+
+				fscanf(cfam_id_file, "0x%" PRIx32, &cfam_id);
+				fclose(cfam_id_file);
+
+				switch((cfam_id >> 4) & 0xff) {
+				case CHIP_ID_P9:
+					device_node = "p9";
+					break;
+
+				case CHIP_ID_P8:
+				case CHIP_ID_P8P:
+					device_node = "p8";
+					break;
+
+				default:
+					PR_ERROR("Unknown chip-id detected\n");
+					PR_ERROR("You will need to specify one with -d <host type>\n");
+					return -1;
+				}
+			} else {
+				/* The support for POWER8 included the cfam_id
+				 * so if it doesn't exist assume we must be on
+				 * P9 */
+				device_node = "p9";
+			}
 		}
+
 		if (!strcmp(device_node, "p8"))
 			pdbg_targets_init(&_binary_p8_kernel_dtb_o_start);
 		else
-- 
2.11.0