regmap: Add support for regmap fields

A regmap field is an abstraction available in Linux. It provides to access
bitfields in a regmap without having to worry about shifts and masks.

Signed-off-by: Jean-Jacques Hiblot <jjhiblot@ti.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Signed-off-by: Pratyush Yadav <p.yadav@ti.com>

1 files changed, 83 insertions, 0 deletions

diff --git a/drivers/core/regmap.c b/drivers/core/regmap.c
index a3da0cf..c2bed88 100644
--- a/drivers/core/regmap.c
+++ b/drivers/core/regmap.c
@@ -18,6 +18,20 @@
 #include <linux/ioport.h>
 #include <linux/compat.h>
 #include <linux/err.h>
+#include <linux/bitops.h>
+
+/*
+ * Internal representation of a regmap field. Instead of storing the MSB and
+ * LSB, store the shift and mask. This makes the code a bit cleaner and faster
+ * because the shift and mask don't have to be calculated every time.
+ */
+struct regmap_field {
+	struct regmap *regmap;
+	unsigned int mask;
+	/* lsb */
+	unsigned int shift;
+	unsigned int reg;
+};
 
 DECLARE_GLOBAL_DATA_PTR;
 
@@ -547,3 +561,72 @@ int regmap_update_bits(struct regmap *map, uint offset, uint mask, uint val)
 
 	return regmap_write(map, offset, reg | (val & mask));
 }
+
+int regmap_field_read(struct regmap_field *field, unsigned int *val)
+{
+	int ret;
+	unsigned int reg_val;
+
+	ret = regmap_read(field->regmap, field->reg, &reg_val);
+	if (ret != 0)
+		return ret;
+
+	reg_val &= field->mask;
+	reg_val >>= field->shift;
+	*val = reg_val;
+
+	return ret;
+}
+
+int regmap_field_write(struct regmap_field *field, unsigned int val)
+{
+	return regmap_update_bits(field->regmap, field->reg, field->mask,
+				  val << field->shift);
+}
+
+static void regmap_field_init(struct regmap_field *rm_field,
+			      struct regmap *regmap,
+			      struct reg_field reg_field)
+{
+	rm_field->regmap = regmap;
+	rm_field->reg = reg_field.reg;
+	rm_field->shift = reg_field.lsb;
+	rm_field->mask = GENMASK(reg_field.msb, reg_field.lsb);
+}
+
+struct regmap_field *devm_regmap_field_alloc(struct udevice *dev,
+					     struct regmap *regmap,
+					     struct reg_field reg_field)
+{
+	struct regmap_field *rm_field = devm_kzalloc(dev, sizeof(*rm_field),
+						     GFP_KERNEL);
+	if (!rm_field)
+		return ERR_PTR(-ENOMEM);
+
+	regmap_field_init(rm_field, regmap, reg_field);
+
+	return rm_field;
+}
+
+void devm_regmap_field_free(struct udevice *dev, struct regmap_field *field)
+{
+	devm_kfree(dev, field);
+}
+
+struct regmap_field *regmap_field_alloc(struct regmap *regmap,
+					struct reg_field reg_field)
+{
+	struct regmap_field *rm_field = kzalloc(sizeof(*rm_field), GFP_KERNEL);
+
+	if (!rm_field)
+		return ERR_PTR(-ENOMEM);
+
+	regmap_field_init(rm_field, regmap, reg_field);
+
+	return rm_field;
+}
+
+void regmap_field_free(struct regmap_field *field)
+{
+	kfree(field);
+}