regmap: Support paging for buses with reg_read()/reg_write()

We don't currently support paging for regmaps where the I/O happens through
bus provided reg_read() and reg_write() operatons, we simply ignore the
range since nothing is wired up properly. Wire things up.
Signed-off-by: Mark Brown <broonie@kernel.org>
Link: https://lore.kernel.org/r/20230324-regmap-reg-read-write-page-v1-1-1fbc0dac67ae@kernel.org

drivers/base/regmap/regmap.c

@@ -1945,6 +1945,15 @@ static int _regmap_bus_reg_write(void *context, unsigned int reg,
 				 unsigned int val)
 {
 	struct regmap *map = context;
+	struct regmap_range_node *range;
+	int ret;
+
+	range = _regmap_range_lookup(map, reg);
+	if (range) {
+		ret = _regmap_select_page(map, &reg, range, 1);
+		if (ret != 0)
+			return ret;
+	}
 
 	reg = regmap_reg_addr(map, reg);
 	return map->bus->reg_write(map->bus_context, reg, val);
@@ -2842,6 +2851,15 @@ static int _regmap_bus_reg_read(void *context, unsigned int reg,
 				unsigned int *val)
 {
 	struct regmap *map = context;
+	struct regmap_range_node *range;
+	int ret;
+
+	range = _regmap_range_lookup(map, reg);
+	if (range) {
+		ret = _regmap_select_page(map, &reg, range, 1);
+		if (ret != 0)
+			return ret;
+	}
 
 	reg = regmap_reg_addr(map, reg);
 	return map->bus->reg_read(map->bus_context, reg, val);