regmap: Add regmap_field APIs

It is common to access regmap registers at bit level, using
regmap_update_bits or regmap_read functions, however the end user has to
take care of a mask or shifting. This becomes overhead when such use
cases are high. Having a common function to do this is much convenient
and less error prone.

The idea of regmap_field is simple, regmap_field gives a logical
structure to bits of the regmap register, and the driver can use this
logical entity without the knowledge of the bit positions and masks all
over the code. This way code looks much neat and it need not handle the
masks, shifts every time it access the those entities.

With this new regmap_field_read/write apis the end user can setup a
regmap field using regmap_field_init and use the return regmap_field to
read write the register field without worrying about the masks or
shifts.

Also this apis will be useful for drivers which are based on regmaps,
like some clocks or pinctrls which can work on the regmap_fields
directly without having to worry about bit positions.

Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@st.com>
Signed-off-by: Mark Brown <broonie@linaro.org>

1 files changed, 31 insertions, 0 deletions

diff --git a/include/linux/regmap.h b/include/linux/regmap.h
index 02d84e24b7c2..eebea9b5f43e 100644
--- a/include/linux/regmap.h
+++ b/include/linux/regmap.h
@@ -23,6 +23,7 @@ struct irq_domain;
 struct spi_device;
 struct regmap;
 struct regmap_range_cfg;
+struct regmap_field;
 
 /* An enum of all the supported cache types */
 enum regcache_type {
@@ -412,6 +413,36 @@ bool regmap_reg_in_ranges(unsigned int reg,
                           unsigned int nranges);
 
 /**
+ * Description of an register field
+ *
+ * @reg: Offset of the register within the regmap bank
+ * @lsb: lsb of the register field.
+ * @reg: msb of the register field.
+ */
+struct reg_field {
+        unsigned int reg;
+        unsigned int lsb;
+        unsigned int msb;
+};
+
+#define REG_FIELD(_reg, _lsb, _msb) {           \
+                                .reg = _reg,    \
+                                .lsb = _lsb,    \
+                                .msb = _msb,    \
+                                }
+
+struct regmap_field *regmap_field_alloc(struct regmap *regmap,
+                struct reg_field reg_field);
+void regmap_field_free(struct regmap_field *field);
+
+struct regmap_field *devm_regmap_field_alloc(struct device *dev,
+                struct regmap *regmap, struct reg_field reg_field);
+void devm_regmap_field_free(struct device *dev, struct regmap_field *field);
+
+int regmap_field_read(struct regmap_field *field, unsigned int *val);
+int regmap_field_write(struct regmap_field *field, unsigned int val);
+
+/**
  * Description of an IRQ for the generic regmap irq_chip.
  *
  * @reg_offset: Offset of the status/mask register within the bank