test: regmap: test Linux-compatible syscon_node_to_regmap()

Like Linux, syscon_node_to_regmap() allows a node to work as a syscon
provider without binding it to a syscon driver.  Test this.

Requested-by: Simon Glass <sjg@chromium.org>
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Reviewed-by: Simon Glass <sjg@chromium.org>

arch/sandbox/dts/test.dts

@@ -393,6 +393,14 @@
 			0x38 8>;
 	};
 
+	syscon@2 {
+		compatible = "simple-mfd", "syscon";
+		reg = <0x40 5
+			0x48 6
+			0x50 7
+			0x58 8>;
+	};
+
 	timer {
 		compatible = "sandbox,timer";
 		clock-frequency = <1000000>;

test/dm/regmap.c

@@ -17,6 +17,7 @@ static int dm_test_regmap_base(struct unit_test_state *uts)
 {
 	struct udevice *dev;
 	struct regmap *map;
+	ofnode node;
 	int i;
 
 	ut_assertok(uclass_get_device(UCLASS_SYSCON, 0, &dev));
@@ -45,6 +46,22 @@ static int dm_test_regmap_base(struct unit_test_state *uts)
 	map = syscon_get_regmap(dev);
 	ut_asserteq_ptr(ERR_PTR(-ENOEXEC), map);
 
+	/* A different device can be a syscon by using Linux-compat API */
+	node = ofnode_path("/syscon@2");
+	ut_assert(ofnode_valid(node));
+
+	map = syscon_node_to_regmap(node);
+	ut_assertok_ptr(map);
+	ut_asserteq(4, map->range_count);
+	ut_asserteq(0x40, map->ranges[0].start);
+	for (i = 0; i < 4; i++) {
+		const unsigned long addr = 0x40 + 8 * i;
+
+		ut_asserteq(addr, map->ranges[i].start);
+		ut_asserteq(5 + i, map->ranges[i].size);
+		ut_asserteq(addr, map_to_sysmem(regmap_get_range(map, i)));
+	}
+
 	return 0;
 }
 DM_TEST(dm_test_regmap_base, DM_TESTF_SCAN_PDATA | DM_TESTF_SCAN_FDT);