regmap: add support for 7/17 register formating

This patch adds support for 7 bits register, 17 bits value type register
formating. This is used, for example, by the Analog Devices
ADMV1013/ADMV1014.
Signed-off-by: Antoniu Miclaus <antoniu.miclaus@analog.com>
Signed-off-by: Andrei Drimbarean <andrei.drimbarean@analog.com>
Message-Id: <20210526085223.14896-1-antoniu.miclaus@analog.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

drivers/base/regmap/regmap.c

@@ -243,6 +243,16 @@ static void regmap_format_7_9_write(struct regmap *map,
 	*out = cpu_to_be16((reg << 9) | val);
 }
 
+static void regmap_format_7_17_write(struct regmap *map,
+				    unsigned int reg, unsigned int val)
+{
+	u8 *out = map->work_buf;
+
+	out[2] = val;
+	out[1] = val >> 8;
+	out[0] = (val >> 16) | (reg << 1);
+}
+
 static void regmap_format_10_14_write(struct regmap *map,
 				    unsigned int reg, unsigned int val)
 {
@@ -885,6 +895,9 @@ struct regmap *__regmap_init(struct device *dev,
 		case 9:
 			map->format.format_write = regmap_format_7_9_write;
 			break;
+		case 17:
+			map->format.format_write = regmap_format_7_17_write;
+			break;
 		default:
 			goto err_hwlock;
 		}