regmap: Implement regmap_multi_reg_read()

regmap_multi_reg_read() is similar to regmap_bilk_read() but reads from
an array of non-sequential registers.
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Link: https://lore.kernel.org/r/20240710015622.1960522-2-linux@roeck-us.netSigned-off-by: Mark Brown <broonie@kernel.org>

drivers/base/regmap/regmap.c

@@ -3101,48 +3101,28 @@ int regmap_fields_read(struct regmap_field *field, unsigned int id,
 }
 EXPORT_SYMBOL_GPL(regmap_fields_read);
 
-/**
- * regmap_bulk_read() - Read multiple registers from the device
- *
- * @map: Register map to read from
- * @reg: First register to be read from
- * @val: Pointer to store read value, in native register size for device
- * @val_count: Number of registers to read
- *
- * A value of zero will be returned on success, a negative errno will
- * be returned in error cases.
- */
-int regmap_bulk_read(struct regmap *map, unsigned int reg, void *val,
-		     size_t val_count)
+static int _regmap_bulk_read(struct regmap *map, unsigned int reg,
+			     unsigned int *regs, void *val, size_t val_count)
 {
-	int ret, i;
-	size_t val_bytes = map->format.val_bytes;
-	bool vol = regmap_volatile_range(map, reg, val_count);
-
-	if (!IS_ALIGNED(reg, map->reg_stride))
-		return -EINVAL;
-	if (val_count == 0)
-		return -EINVAL;
-
-	if (map->read && map->format.parse_inplace && (vol || map->cache_type == REGCACHE_NONE)) {
-		ret = regmap_raw_read(map, reg, val, val_bytes * val_count);
-		if (ret != 0)
-			return ret;
-
-		for (i = 0; i < val_count * val_bytes; i += val_bytes)
-			map->format.parse_inplace(val + i);
-	} else {
 	u32 *u32 = val;
 	u16 *u16 = val;
 	u8 *u8 = val;
+	int ret, i;
 
 	map->lock(map->lock_arg);
 
 	for (i = 0; i < val_count; i++) {
 		unsigned int ival;
 
-			ret = _regmap_read(map, reg + regmap_get_offset(map, i),
-					   &ival);
+		if (regs) {
+			if (!IS_ALIGNED(regs[i], map->reg_stride)) {
+				ret = -EINVAL;
+				goto out;
+			}
+			ret = _regmap_read(map, regs[i], &ival);
+		} else {
+			ret = _regmap_read(map, reg + regmap_get_offset(map, i), &ival);
+		}
 		if (ret != 0)
 			goto out;
 
@@ -3161,18 +3141,71 @@ int regmap_bulk_read(struct regmap *map, unsigned int reg, void *val,
 			goto out;
 		}
 	}
-
 out:
 	map->unlock(map->lock_arg);
-	}
+	return ret;
+}
+
+/**
+ * regmap_bulk_read() - Read multiple sequential registers from the device
+ *
+ * @map: Register map to read from
+ * @reg: First register to be read from
+ * @val: Pointer to store read value, in native register size for device
+ * @val_count: Number of registers to read
+ *
+ * A value of zero will be returned on success, a negative errno will
+ * be returned in error cases.
+ */
+int regmap_bulk_read(struct regmap *map, unsigned int reg, void *val,
+		     size_t val_count)
+{
+	int ret, i;
+	size_t val_bytes = map->format.val_bytes;
+	bool vol = regmap_volatile_range(map, reg, val_count);
+
+	if (!IS_ALIGNED(reg, map->reg_stride))
+		return -EINVAL;
+	if (val_count == 0)
+		return -EINVAL;
+
+	if (map->read && map->format.parse_inplace && (vol || map->cache_type == REGCACHE_NONE)) {
+		ret = regmap_raw_read(map, reg, val, val_bytes * val_count);
+		if (ret != 0)
+			return ret;
 
+		for (i = 0; i < val_count * val_bytes; i += val_bytes)
+			map->format.parse_inplace(val + i);
+	} else {
+		ret = _regmap_bulk_read(map, reg, NULL, val, val_count);
+	}
 	if (!ret)
 		trace_regmap_bulk_read(map, reg, val, val_bytes * val_count);
-
 	return ret;
 }
 EXPORT_SYMBOL_GPL(regmap_bulk_read);
 
+/**
+ * regmap_multi_reg_read() - Read multiple non-sequential registers from the device
+ *
+ * @map: Register map to read from
+ * @regs: Array of registers to read from
+ * @val: Pointer to store read value, in native register size for device
+ * @val_count: Number of registers to read
+ *
+ * A value of zero will be returned on success, a negative errno will
+ * be returned in error cases.
+ */
+int regmap_multi_reg_read(struct regmap *map, unsigned int *regs, void *val,
+			  size_t val_count)
+{
+	if (val_count == 0)
+		return -EINVAL;
+
+	return _regmap_bulk_read(map, 0, regs, val, val_count);
+}
+EXPORT_SYMBOL_GPL(regmap_multi_reg_read);
+
 static int _regmap_update_bits(struct regmap *map, unsigned int reg,
 			       unsigned int mask, unsigned int val,
 			       bool *change, bool force_write)

include/linux/regmap.h

@@ -1237,6 +1237,8 @@ int regmap_noinc_read(struct regmap *map, unsigned int reg,
 		      void *val, size_t val_len);
 int regmap_bulk_read(struct regmap *map, unsigned int reg, void *val,
 		     size_t val_count);
+int regmap_multi_reg_read(struct regmap *map, unsigned int *reg, void *val,
+			  size_t val_count);
 int regmap_update_bits_base(struct regmap *map, unsigned int reg,
 			    unsigned int mask, unsigned int val,
 			    bool *change, bool async, bool force);