[RFC PATCH 1/3] regmap: Implement regmap_multi_reg_read()

[Guenter Roeck]

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@xxxxxxxxxxxx>
---
 drivers/base/regmap/regmap.c | 103 +++++++++++++++++++++++------------
 include/linux/regmap.h       |   2 +
 2 files changed, 70 insertions(+), 35 deletions(-)

diff --git a/drivers/base/regmap/regmap.c b/drivers/base/regmap/regmap.c
index 0a34dd3c4f38..dff6c515305a 100644
--- a/drivers/base/regmap/regmap.c
+++ b/drivers/base/regmap/regmap.c
@@ -3101,8 +3101,53 @@ int regmap_fields_read(struct regmap_field *field, unsigned int id,
 }
 EXPORT_SYMBOL_GPL(regmap_fields_read);
 
+static int _regmap_bulk_read(struct regmap *map, unsigned int reg,
+			     unsigned int *regs, void *val, size_t val_count)
+{
+	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;
+
+		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;
+
+		switch (map->format.val_bytes) {
+		case 4:
+			u32[i] = ival;
+			break;
+		case 2:
+			u16[i] = ival;
+			break;
+		case 1:
+			u8[i] = ival;
+			break;
+		default:
+			ret = -EINVAL;
+			goto out;
+		}
+	}
+out:
+	map->unlock(map->lock_arg);
+	return ret;
+}
+
 /**
- * regmap_bulk_read() - Read multiple registers from the device
+ * regmap_bulk_read() - Read multiple sequential registers from the device
  *
  * @map: Register map to read from
  * @reg: First register to be read from
@@ -3132,47 +3177,35 @@ int regmap_bulk_read(struct regmap *map, unsigned int reg, void *val,
 		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;
-
-		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 (ret != 0)
-				goto out;
-
-			switch (map->format.val_bytes) {
-			case 4:
-				u32[i] = ival;
-				break;
-			case 2:
-				u16[i] = ival;
-				break;
-			case 1:
-				u8[i] = ival;
-				break;
-			default:
-				ret = -EINVAL;
-				goto out;
-			}
-		}
-
-out:
-		map->unlock(map->lock_arg);
+		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)
diff --git a/include/linux/regmap.h b/include/linux/regmap.h
index a6bc2980a98b..9c1ddbf82719 100644
--- a/include/linux/regmap.h
+++ b/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);
-- 
2.39.2