[PATCH v2 2/4] regulator: Support regulators where the voltage selector spans two registers

[Paul Louvel <paul.louvel@bootlin.com>]

Some devices uses 8-bit registers to store the voltage selector across
two registers: one for the least significant bits and one for the most
significant bits.

Introduce vsel_reg_oversize to support voltage selectors that span two
registers. Write the selector in bulk across both registers using
little-endian encoding.

Assume that future hardware will require at most one additional register
to store the voltage selector, and that only a device with 8-bit
register will require such flag.

Signed-off-by: Paul Louvel <paul.louvel@bootlin.com>
---
 drivers/regulator/helpers.c      | 87 +++++++++++++++++++++++++++++++++-------
 include/linux/regulator/driver.h |  2 +
 2 files changed, 74 insertions(+), 15 deletions(-)

diff --git a/drivers/regulator/helpers.c b/drivers/regulator/helpers.c
index 0def82eb8b46..d4b53803ae12 100644
--- a/drivers/regulator/helpers.c
+++ b/drivers/regulator/helpers.c
@@ -118,6 +118,35 @@ static int regulator_range_selector_to_index(struct regulator_dev *rdev,
 	return -EINVAL;
 }
 
+static int get_voltage_sel_reg(struct regulator_dev *rdev, unsigned int *sel)
+{
+	unsigned int val;
+	__le16 buf;
+	int ret;
+
+	if (rdev->desc->vsel_reg_oversize) {
+		if (regmap_get_val_bytes(rdev->regmap) != 1)
+			return -EINVAL;
+
+		ret = regmap_bulk_read(rdev->regmap, rdev->desc->vsel_reg, &buf, 2);
+		if (ret != 0)
+			return ret;
+
+		val = le16_to_cpu(buf);
+	} else {
+		ret = regmap_read(rdev->regmap, rdev->desc->vsel_reg, &val);
+		if (ret != 0)
+			return ret;
+	}
+
+	val &= rdev->desc->vsel_mask;
+	val >>= ffs(rdev->desc->vsel_mask) - 1;
+
+	*sel = val;
+
+	return 0;
+}
+
 /**
  * regulator_get_voltage_sel_pickable_regmap - pickable range get_voltage_sel
  *
@@ -140,7 +169,7 @@ int regulator_get_voltage_sel_pickable_regmap(struct regulator_dev *rdev)
 	if (!r)
 		return -EINVAL;
 
-	ret = regmap_read(rdev->regmap, rdev->desc->vsel_reg, &val);
+	ret = get_voltage_sel_reg(rdev, &val);
 	if (ret != 0)
 		return ret;
 
@@ -148,9 +177,6 @@ int regulator_get_voltage_sel_pickable_regmap(struct regulator_dev *rdev)
 	if (ret != 0)
 		return ret;
 
-	val &= rdev->desc->vsel_mask;
-	val >>= ffs(rdev->desc->vsel_mask) - 1;
-
 	range = regulator_range_selector_to_index(rdev, r_val);
 	if (range < 0)
 		return -EINVAL;
@@ -161,6 +187,29 @@ int regulator_get_voltage_sel_pickable_regmap(struct regulator_dev *rdev)
 }
 EXPORT_SYMBOL_GPL(regulator_get_voltage_sel_pickable_regmap);
 
+static int set_oversize_voltage_sel(struct regulator_dev *rdev,
+				    unsigned int sel)
+{
+	unsigned int mask = rdev->desc->vsel_mask;
+	__le16 buf;
+	u16 val;
+	int ret;
+
+	if (regmap_get_val_bytes(rdev->regmap) != 1)
+		return -EINVAL;
+
+	ret = regmap_bulk_read(rdev->regmap, rdev->desc->vsel_reg, &buf, 2);
+	if (ret)
+		return ret;
+
+	val = le16_to_cpu(buf);
+	val = (val & ~mask) | (sel & mask);
+
+	buf = cpu_to_le16(val);
+
+	return regmap_bulk_write(rdev->regmap, rdev->desc->vsel_reg, &buf, 2);
+}
+
 static int write_separate_vsel_and_range(struct regulator_dev *rdev,
 					 unsigned int sel, unsigned int range)
 {
@@ -173,15 +222,17 @@ static int write_separate_vsel_and_range(struct regulator_dev *rdev,
 	if (ret)
 		return ret;
 
+	if (rdev->desc->vsel_reg_oversize)
+		return set_oversize_voltage_sel(rdev, sel);
+
 	/*
 	 * Some PMICs treat the vsel_reg same as apply-bit. Force it to be
 	 * written if the range changed, even if the old selector was same as
 	 * the new one
 	 */
 	if (rdev->desc->range_applied_by_vsel && range_updated)
-		return regmap_write_bits(rdev->regmap,
-					rdev->desc->vsel_reg,
-					rdev->desc->vsel_mask, sel);
+		return regmap_write_bits(rdev->regmap, rdev->desc->vsel_reg,
+					 rdev->desc->vsel_mask, sel);
 
 	return regmap_update_bits(rdev->regmap, rdev->desc->vsel_reg,
 				  rdev->desc->vsel_mask, sel);
@@ -225,12 +276,16 @@ int regulator_set_voltage_sel_pickable_regmap(struct regulator_dev *rdev,
 	range = rdev->desc->linear_range_selectors_bitfield[i];
 	range <<= ffs(rdev->desc->vsel_range_mask) - 1;
 
-	if (rdev->desc->vsel_reg == rdev->desc->vsel_range_reg)
+	if (rdev->desc->vsel_reg == rdev->desc->vsel_range_reg) {
+		if (rdev->desc->vsel_reg_oversize)
+			return -EINVAL;
+
 		ret = regmap_update_bits(rdev->regmap, rdev->desc->vsel_reg,
 					 rdev->desc->vsel_range_mask |
 					 rdev->desc->vsel_mask, sel | range);
-	else
+	} else {
 		ret = write_separate_vsel_and_range(rdev, sel, range);
+	}
 
 	if (ret)
 		return ret;
@@ -257,17 +312,15 @@ int regulator_get_voltage_sel_regmap(struct regulator_dev *rdev)
 	unsigned int val;
 	int ret;
 
-	ret = regmap_read(rdev->regmap, rdev->desc->vsel_reg, &val);
+	ret = get_voltage_sel_reg(rdev, &val);
 	if (ret != 0)
 		return ret;
 
-	val &= rdev->desc->vsel_mask;
-	val >>= ffs(rdev->desc->vsel_mask) - 1;
-
 	return val;
 }
 EXPORT_SYMBOL_GPL(regulator_get_voltage_sel_regmap);
 
+
 /**
  * regulator_set_voltage_sel_regmap - standard set_voltage_sel for regmap users
  *
@@ -284,8 +337,12 @@ int regulator_set_voltage_sel_regmap(struct regulator_dev *rdev, unsigned sel)
 
 	sel <<= ffs(rdev->desc->vsel_mask) - 1;
 
-	ret = regmap_update_bits(rdev->regmap, rdev->desc->vsel_reg,
-				  rdev->desc->vsel_mask, sel);
+	if (rdev->desc->vsel_reg_oversize)
+		ret = set_oversize_voltage_sel(rdev, sel);
+	else
+		ret = regmap_update_bits(rdev->regmap, rdev->desc->vsel_reg,
+					 rdev->desc->vsel_mask, sel);
+
 	if (ret)
 		return ret;
 
diff --git a/include/linux/regulator/driver.h b/include/linux/regulator/driver.h
index 55cc519103ed..8a0f3aebdade 100644
--- a/include/linux/regulator/driver.h
+++ b/include/linux/regulator/driver.h
@@ -312,6 +312,7 @@ enum regulator_type {
  * @range_applied_by_vsel: A flag to indicate that changes to vsel_range_reg
  *			   are only effective after vsel_reg is written
  * @vsel_reg: Register for selector when using ``regulator_map_*_voltage_*``
+ * @vsel_reg_oversize: Indicates that the vsel_reg spans on two registers
  * @vsel_mask: Mask for register bitfield used for selector
  * @vsel_step: Specify the resolution of selector stepping when setting
  *	       voltage. If 0, then no stepping is done (requested selector is
@@ -405,6 +406,7 @@ struct regulator_desc {
 	unsigned int vsel_range_mask;
 	bool range_applied_by_vsel;
 	unsigned int vsel_reg;
+	bool vsel_reg_oversize;
 	unsigned int vsel_mask;
 	unsigned int vsel_step;
 	unsigned int csel_reg;

-- 
2.56.0