lk2nd: dev_tree: Mark as best dtb node if compatible matches with lk2nd dtb

Makes sure we load the correct dtb node based on lk2nd's device
selection logic when boot.img contains multiple dtbs with same ids.

For example, on msm8953-xiaomi-common.dts, we see 3 devices sharing
the same msm-id and board-id. If a given boot.img contains dtbs for
all these devices, without this logic lk2nd will always load the
first of these dtbs, regardless of the device it's being run on.

Try using compatible string from `dtb_compatible` property first,
because there's some devices supposed to use some other devices' dtb
in mainline kernel (e.g. xiaomi-sakura uses xiaomi-daisy dtb).

This shouldn't affect booting downstream kernels, since they normally
don't define `<vendor>,<device>` on their dts compatible.

Change-Id: Ib7ed0908038f178d34eaa6b4952691c17055c22b

Author: me-cafebabe

lk2nd/device/device.c

@@ -24,6 +24,14 @@ const char *const *lk2nd_device_get_dtb_hints(void)
 	return lk2nd_dev.dtbfiles;
 }
 
+/**
+ * lk2nd_device_get_dtb_compatible() - Get a compatible string for matching kernel dtb.
+ */
+const char *lk2nd_device_get_dtb_compatible(void)
+{
+	return lk2nd_dev.dtb_compatible ? lk2nd_dev.dtb_compatible : lk2nd_dev.compatible;
+}
+
 static int find_device_node(const void *dtb)
 {
 	int lk2nd_node, node, ret;
@@ -112,6 +120,12 @@ static void parse_dtb(const void *dtb)
 	else
 		dprintf(CRITICAL, "Failed to read 'compatible': %d\n", len);
 
+	val = fdt_getprop(dtb, node, "dtb_compatible", &len);
+	if (val && len > 0)
+		lk2nd_dev.dtb_compatible = strndup(val, len);
+	else
+		dprintf(CRITICAL, "Failed to read 'dtb_compatible': %d\n", len);
+
 	val = fdt_getprop(dtb, node, "model", &len);
 	if (val && len > 0)
 		lk2nd_dev.model = strndup(val, len);

lk2nd/device/device.h

@@ -29,6 +29,7 @@ struct lk2nd_device {
 	const char *model;
 	const char *battery;
 
+	const char *dtb_compatible;
 	const char *const *dtbfiles;
 	bool single_key;
 	struct lk2nd_menu_keys menu_keys;

lk2nd/include/lk2nd/device.h

@@ -12,8 +12,10 @@ void lk2nd_device2nd_copy_atags(void *tags, const char *cmdline,
 
 #if WITH_LK2ND_DEVICE
 const char *const *lk2nd_device_get_dtb_hints(void);
+const char *lk2nd_device_get_dtb_compatible(void);
 #else
 static inline const char *const *lk2nd_device_get_dtb_hints(void) { return NULL; };
+static inline const char *lk2nd_device_get_dtb_compatible(void) { return NULL; };
 #endif
 
 #endif /* LK2ND_DEVICE_H */

platform/msm_shared/dev_tree.c

@@ -50,6 +50,9 @@
 #endif
 #include <boot_stats.h>
 #include <verifiedboot.h>
+#if WITH_LK2ND_DEVICE
+#include <lk2nd/device.h>
+#endif
 
 #define NODE_PROPERTY_MAX_LEN   64
 #define ADD_OF(a, b) (UINT_MAX - b > a) ? (a + b) : UINT_MAX
@@ -401,6 +404,15 @@ static boolean dtb_read_find_match(dt_info *current_dtb_info, dt_info *best_dtb_
 		return false;
 	}
 
+#if WITH_LK2ND_DEVICE
+	if (fdt_node_check_compatible(dtb, root_offset, lk2nd_device_get_dtb_compatible()) == 0) {
+		dprintf(INFO, "Compatible %s matches, mark as best dtb node\n", lk2nd_device_get_dtb_compatible());
+		current_dtb_info->dt_match_val = UINT_MAX;
+		current_dtb_info->dt_match_val &= ~exact_match;
+		goto cleanup;
+	}
+#endif
+
 	/* Get the msm-id prop from DTB and find best match */
 	platform_prop = (const char *)fdt_getprop(dtb, root_offset, "qcom,msm-id", &platform_id_len);
 	if (platform_prop && (platform_id_len > 0) && (!(platform_id_len % PLAT_ID_SIZE))) {
@@ -823,6 +835,7 @@ static int dev_tree_compatible(const void *dtb, const void *real_dtb, uint32_t d
 	uint32_t board_data_count;
 	uint32_t pmic_data_count;
 	uint32_t dtb_count = 0;;
+	bool set_dt_entry_is_best = false;
 
 	if (!root_offset)
 		root_offset = fdt_path_offset(dtb, "/");
@@ -840,6 +853,13 @@ if (DEBUGLEVEL >= SPEW) {
 	}
 }
 
+#if WITH_LK2ND_DEVICE
+	if (fdt_node_check_compatible(dtb, root_offset, lk2nd_device_get_dtb_compatible()) == 0) {
+		dprintf(INFO, "Compatible %s matches, mark as best dtb node\n", lk2nd_device_get_dtb_compatible());
+		set_dt_entry_is_best = true;
+	}
+#endif
+
 	/* Find the pmic-id prop from DTB , if pmic-id is present then
 	* the DTB is version 3, otherwise find the board-id prop from DTB ,
 	* if board-id is present then the DTB is version 2 */
@@ -921,6 +941,7 @@ if (DEBUGLEVEL >= SPEW) {
 			cur_dt_entry->pmic_rev[3] = board_pmic_target(3);
 			cur_dt_entry->offset = (uint32_t)real_dtb;
 			cur_dt_entry->size = dtb_size;
+			cur_dt_entry->is_best = set_dt_entry_is_best;
 
 			if (min_plat_id_len == DT_ENTRY_LGE8974_SIZE)
 				cur_dt_entry->board_hw_subtype = fdt32_to_cpu(((const struct dt_entry_v1 *)plat_prop)->offset);
@@ -1076,6 +1097,7 @@ if (DEBUGLEVEL >= SPEW) {
 						dt_entry_array[k].pmic_rev[3]= pmic_data[n].pmic_version[3];
 						dt_entry_array[k].offset = (uint32_t)real_dtb;
 						dt_entry_array[k].size = dtb_size;
+						dt_entry_array[k].is_best = set_dt_entry_is_best;
 						k++;
 					}
 
@@ -1090,6 +1112,7 @@ if (DEBUGLEVEL >= SPEW) {
 					dt_entry_array[k].pmic_rev[3]= board_pmic_target(3);
 					dt_entry_array[k].offset = (uint32_t)real_dtb;
 					dt_entry_array[k].size = dtb_size;
+					dt_entry_array[k].is_best = set_dt_entry_is_best;
 					k++;
 				}
 			}
@@ -1829,6 +1852,20 @@ static struct dt_entry *platform_dt_match_best(struct dt_entry_node *dt_list)
 	if (!update_dtb_entry_node(dt_list, DTB_PMIC3))
 		return NULL;
 
+#if WITH_LK2ND_DEVICE
+	list_for_every_entry(&dt_list->node, dt_node_tmp1, dt_node, node) {
+		if (!dt_node_tmp1)
+			break;
+
+		if (!dt_node_tmp1->dt_entry_m)
+			continue;
+
+		if (dt_node_tmp1->dt_entry_m->is_best) {
+			return dt_node_tmp1->dt_entry_m;
+		}
+	}
+#endif
+
 	list_for_every_entry(&dt_list->node, dt_node_tmp1, dt_node, node) {
 		if (!dt_node_tmp1) {
 			dprintf(CRITICAL, "ERROR: Couldn't find the suitable DTB!\n");

platform/msm_shared/include/dev_tree.h

@@ -169,6 +169,7 @@ struct dt_entry
 	uint32_t offset;
 	uint32_t size;
 	uint32_t idx;
+	bool is_best;
 };
 
 struct dt_table