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>

diff --git a/drivers/core/regmap.c b/drivers/core/regmap.c
index a3da0cf..c2bed88 100644 (file)
--- 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);
+}

diff --git a/include/regmap.h b/include/regmap.h
index 7a6fcc7..c6258fa 100644 (file)
--- a/include/regmap.h
+++ b/include/regmap.h
@@ -313,6 +313,43 @@ int regmap_raw_read_range(struct regmap *map, uint range_num, uint offset,
                                      timeout_ms, 0) \
 
 /**
+ * regmap_field_read_poll_timeout - Poll until a condition is met or a timeout
+ *                                 occurs
+ *
+ * @field:     Regmap field to read from
+ * @val:       Unsigned integer variable to read the value into
+ * @cond:      Break condition (usually involving @val)
+ * @sleep_us:  Maximum time to sleep between reads in us (0 tight-loops).
+ * @timeout_ms:        Timeout in ms, 0 means never timeout
+ *
+ * Returns 0 on success and -ETIMEDOUT upon a timeout or the regmap_field_read
+ * error return value in case of a error read. In the two former cases,
+ * the last read value at @addr is stored in @val.
+ *
+ * This is modelled after the regmap_read_poll_timeout macros in linux but
+ * with millisecond timeout.
+ */
+#define regmap_field_read_poll_timeout(field, val, cond, sleep_us, timeout_ms) \
+({ \
+       unsigned long __start = get_timer(0); \
+       int __ret; \
+       for (;;) { \
+               __ret = regmap_field_read((field), &(val)); \
+               if (__ret) \
+                       break; \
+               if (cond) \
+                       break; \
+               if ((timeout_ms) && get_timer(__start) > (timeout_ms)) { \
+                       __ret = regmap_field_read((field), &(val)); \
+                       break; \
+               } \
+               if ((sleep_us)) \
+                       udelay((sleep_us)); \
+       } \
+       __ret ?: ((cond) ? 0 : -ETIMEDOUT); \
+})
+
+/**
  * regmap_update_bits() - Perform a read/modify/write using a mask
  *
  * @map:       The map returned by regmap_init_mem*()
@@ -407,4 +444,89 @@ void *regmap_get_range(struct regmap *map, unsigned int range_num);
  */
 int regmap_uninit(struct regmap *map);
 
+/**
+ * struct reg_field - Description of an register field
+ *
+ * @reg: Offset of the register within the regmap bank
+ * @lsb: lsb of the register field.
+ * @msb: msb of the register field.
+ */
+struct reg_field {
+       unsigned int reg;
+       unsigned int lsb;
+       unsigned int msb;
+};
+
+struct regmap_field;
+
+/**
+ * REG_FIELD() - A convenient way to initialize a 'struct reg_feild'.
+ *
+ * @_reg: Offset of the register within the regmap bank
+ * @_lsb: lsb of the register field.
+ * @_msb: msb of the register field.
+ *
+ * Register fields are often described in terms of 3 things: the register it
+ * belongs to, its LSB, and its MSB. This macro can be used by drivers to
+ * clearly and easily initialize a 'struct regmap_field'.
+ *
+ * For example, say a device has a register at offset DEV_REG1 (0x100) and a
+ * field of DEV_REG1 is on bits [7:3]. So a driver can initialize a regmap
+ * field for this by doing:
+ *     struct reg_field field = REG_FIELD(DEV_REG1, 3, 7);
+ */
+#define REG_FIELD(_reg, _lsb, _msb) {          \
+                               .reg = _reg,    \
+                               .lsb = _lsb,    \
+                               .msb = _msb,    \
+                               }
+
+/**
+ * devm_regmap_field_alloc() - Allocate and initialise a register field.
+ *
+ * @dev: Device that will be interacted with
+ * @regmap: regmap bank in which this register field is located.
+ * @reg_field: Register field with in the bank.
+ *
+ * The return value will be an ERR_PTR() on error or a valid pointer
+ * to a struct regmap_field. The regmap_field will be automatically freed
+ * by the device management code.
+ */
+struct regmap_field *devm_regmap_field_alloc(struct udevice *dev,
+                                            struct regmap *regmap,
+                                            struct reg_field reg_field);
+/**
+ * devm_regmap_field_free() - Free a register field allocated using
+ *                            devm_regmap_field_alloc.
+ *
+ * @dev: Device that will be interacted with
+ * @field: regmap field which should be freed.
+ *
+ * Free register field allocated using devm_regmap_field_alloc(). Usually
+ * drivers need not call this function, as the memory allocated via devm
+ * will be freed as per device-driver life-cyle.
+ */
+void devm_regmap_field_free(struct udevice *dev, struct regmap_field *field);
+
+/**
+ * regmap_field_write() - Write a value to a regmap field
+ *
+ * @field:     Regmap field to write to
+ * @val:       Data to write to the regmap at the specified offset
+ *
+ * Return: 0 if OK, -ve on error
+ */
+int regmap_field_write(struct regmap_field *field, unsigned int val);
+
+/**
+ * regmap_read() - Read a 32-bit value from a regmap
+ *
+ * @field:     Regmap field to write to
+ * @valp:      Pointer to the buffer to receive the data read from the regmap
+ *             field
+ *
+ * Return: 0 if OK, -ve on error
+ */
+int regmap_field_read(struct regmap_field *field, unsigned int *val);
+
 #endif