devicetree: Add vendor name helpers based on vendor prefixes

Adds vendor name helpers to access generated macros based on matching
entries in the vendor prefixes file.

Signed-off-by: Maureen Helm <maureen.helm@intel.com>

include/zephyr/devicetree.h

@@ -1712,6 +1712,94 @@
  * @}
  */
 
+/**
+ * @defgroup devicetree-generic-vendor Vendor name helpers
+ * @ingroup devicetree
+ * @{
+ */
+
+/**
+ * @brief Get the vendor at index "idx" as a string literal
+ *
+ * The vendor is a string extracted from vendor prefixes if an entry exists
+ * that matches the node's compatible prefix. There may be as many as one
+ * vendor prefixes file per directory in DTS_ROOT.
+ *
+ * Example vendor-prefixes.txt:
+ *
+ *	vnd	A stand-in for a real vendor
+ *	zephyr	Zephyr-specific binding
+ *
+ * Example devicetree fragment:
+ *
+ *	n1: node-1 {
+ *		compatible = "vnd,model1", "gpio", "zephyr,model2";
+ *	};
+ *
+ * Example usage:
+ *
+ *	DT_NODE_VENDOR_BY_IDX(DT_NODELABEL(n1), 0) // "A stand-in for a real vendor"
+ *	DT_NODE_VENDOR_BY_IDX(DT_NODELABEL(n1), 2) // "Zephyr-specific binding"
+ *
+ * Notice that the compatible at index 1 doesn't match any entries in the
+ * vendor prefix file and therefore index 1 is not a valid vendor index. Use
+ * DT_NODE_VENDOR_HAS_IDX(node_id, idx) to determine if an index is valid.
+ *
+ * @param node_id node identifier
+ * @param idx index of the vendor to return
+ * @return string literal of the idx-th vendor
+ */
+#define DT_NODE_VENDOR_BY_IDX(node_id, idx) \
+	DT_CAT(node_id, _COMPAT_VENDOR_IDX_##idx)
+
+/**
+ * @brief Does a node's compatible property have a vendor at an index?
+ *
+ * If this returns 1, then DT_NODE_VENDOR_BY_IDX(node_id, idx) is valid. If it
+ * returns 0, it is an error to use DT_NODE_VENDOR_BY_IDX(node_id, idx) with
+ * index "idx".
+ *
+ * @param node_id node identifier
+ * @param idx index of the vendor to check
+ * @return 1 if "idx" is a valid vendor index,
+ *         0 otherwise.
+ */
+#define DT_NODE_VENDOR_HAS_IDX(node_id, idx) \
+	IS_ENABLED(DT_CAT4(node_id, _COMPAT_VENDOR_IDX_, idx, _EXISTS))
+
+/**
+ * @brief Like DT_NODE_VENDOR_BY_IDX(), but with a fallback to default_value.
+ *
+ * If the value exists, this expands to DT_NODE_VENDOR_BY_IDX(node_id, idx).
+ * The default_value parameter is not expanded in this case.
+ *
+ * Otherwise, this expands to default_value.
+ *
+ * @param node_id node identifier
+ * @param idx index of the vendor to return
+ * @return string literal of the idx-th vendor
+ * @param default_value a fallback value to expand to
+ * @return string literal of the idx-th vendor or "default_value"
+ */
+#define DT_NODE_VENDOR_BY_IDX_OR(node_id, idx, default_value) \
+	COND_CODE_1(DT_NODE_VENDOR_HAS_IDX(node_id, idx), \
+		    (DT_NODE_VENDOR_BY_IDX(node_id, idx)), (default_value))
+
+/**
+ * @brief Get the node's (only) vendor as a string literal
+ *
+ * Equivalent to DT_NODE_VENDOR_BY_IDX_OR(node_id, 0, default_value).
+ *
+ * @param node_id node identifier
+ * @param default_value a fallback value to expand to
+ */
+#define DT_NODE_VENDOR_OR(node_id, default_value) \
+	DT_NODE_VENDOR_BY_IDX_OR(node_id, 0, default_value)
+
+/**
+ * @}
+ */
+
 /**
  * @defgroup devicetree-reg-prop reg property
  * @ingroup devicetree

tests/lib/devicetree/api/app.overlay

@@ -344,6 +344,11 @@
 			misc-prop = <1234>;
 		};
 
+		test_vendor: vendor {
+			compatible = "vnd,model1", "gpio", "zephyr,model2";
+			status = "okay";
+		};
+
 		test_intc: interrupt-controller@bbbbcccc  {
 			compatible = "vnd,intc";
 			reg = <0xbbbbcccc 0x1000>;

tests/lib/devicetree/api/src/main.c

@@ -36,6 +36,7 @@
 #define TEST_IRQ	DT_NODELABEL(test_irq)
 #define TEST_TEMP	DT_NODELABEL(test_temp_sensor)
 #define TEST_REG	DT_NODELABEL(test_reg)
+#define TEST_VENDOR	DT_NODELABEL(test_vendor)
 #define TEST_ENUM_0	DT_NODELABEL(test_enum_0)
 
 #define TEST_I2C DT_NODELABEL(test_i2c)
@@ -398,6 +399,34 @@ ZTEST(devicetree_api, test_bus)
 		      NULL);
 }
 
+#undef DT_DRV_COMPAT
+#define DT_DRV_COMPAT vnd_vendor
+
+#define VND_VENDOR "A stand-in for a real vendor which can be used in examples and tests"
+#define ZEP_VENDOR "Zephyr-specific binding"
+
+ZTEST(devicetree_api, test_vendor)
+{
+	/* DT_NODE_VENDOR_HAS_IDX */
+	zassert_true(DT_NODE_VENDOR_HAS_IDX(TEST_VENDOR, 0), "");
+	zassert_false(DT_NODE_VENDOR_HAS_IDX(TEST_VENDOR, 1), "");
+	zassert_true(DT_NODE_VENDOR_HAS_IDX(TEST_VENDOR, 2), "");
+	zassert_false(DT_NODE_VENDOR_HAS_IDX(TEST_VENDOR, 3), "");
+
+	/* DT_NODE_VENDOR_BY_IDX */
+	zassert_true(!strcmp(DT_NODE_VENDOR_BY_IDX(TEST_VENDOR, 0), VND_VENDOR), "");
+	zassert_true(!strcmp(DT_NODE_VENDOR_BY_IDX(TEST_VENDOR, 2), ZEP_VENDOR), "");
+
+	/* DT_NODE_VENDOR_BY_IDX_OR */
+	zassert_true(!strcmp(DT_NODE_VENDOR_BY_IDX_OR(TEST_VENDOR, 0, NULL), VND_VENDOR), "");
+	zassert_is_null(DT_NODE_VENDOR_BY_IDX_OR(TEST_VENDOR, 1, NULL), "");
+	zassert_true(!strcmp(DT_NODE_VENDOR_BY_IDX_OR(TEST_VENDOR, 2, NULL), ZEP_VENDOR), "");
+	zassert_is_null(DT_NODE_VENDOR_BY_IDX_OR(TEST_VENDOR, 3, NULL), "");
+
+	/* DT_NODE_VENDOR_OR */
+	zassert_true(!strcmp(DT_NODE_VENDOR_OR(TEST_VENDOR, NULL), VND_VENDOR), "");
+}
+
 #undef DT_DRV_COMPAT
 #define DT_DRV_COMPAT vnd_reg_holder
 ZTEST(devicetree_api, test_reg)