From: Peter Crosthwaite <peter.crosthwa...@xilinx.com>
Define some macros that can be used for defining registers and fields.
The REG32 macro will define A_FOO, for the byte address of a register
as well as R_FOO for the uint32_t[] register number (A_FOO / 4).
The FIELD macro will define FOO_BAR_MASK, FOO_BAR_SHIFT and
FOO_BAR_LENGTH constants for field BAR in register FOO.
Finally, there are some shorthand helpers for extracting/depositing
fields from registers based on these naming schemes.
Usage can greatly reduce the verbosity of device code.
The deposit and extract macros (eg FIELD_EX32, FIELD_DP32 etc.) can be
used to generate extract and deposits without any repetition of the name
stems.
Signed-off-by: Peter Crosthwaite <peter.crosthwa...@xilinx.com>
[ EI Changes:
* Add Deposit macros
]
Signed-off-by: Edgar E. Iglesias <edgar.igles...@xilinx.com>
Signed-off-by: Alistair Francis <alistair.fran...@xilinx.com>
---
E.g. Currently you have to define something like:
\#define R_FOOREG (0x84/4)
\#define R_FOOREG_BARFIELD_SHIFT 10
\#define R_FOOREG_BARFIELD_LENGTH 5
uint32_t foobar_val = extract32(s->regs[R_FOOREG],
R_FOOREG_BARFIELD_SHIFT,
R_FOOREG_BARFIELD_LENGTH);
Which has:
2 macro definitions per field
3 register names ("FOOREG") per extract
2 field names ("BARFIELD") per extract
With these macros this becomes:
REG32(FOOREG, 0x84)
FIELD(FOOREG, BARFIELD, 10, 5)
uint32_t foobar_val = ARRAY_FIELD_EX32(s->regs, FOOREG, BARFIELD)
Which has:
1 macro definition per field
1 register name per extract
1 field name per extract
If you are not using arrays for the register data you can just use the
non-array "FIELD_" variants and still save 2 name stems:
uint32_t foobar_val = FIELD_EX32(s->fooreg, FOOREG, BARFIELD)
Deposit is similar for depositing values. Deposit has compile-time
overflow checking for literals.
For example:
REG32(XYZ1, 0x84)
FIELD(XYZ1, TRC, 0, 4)
/* Correctly set XYZ1.TRC = 5. */
ARRAY_FIELD_DP32(s->regs, XYZ1, TRC, 5);
/* Incorrectly set XYZ1.TRC = 16. */
ARRAY_FIELD_DP32(s->regs, XYZ1, TRC, 16);
The latter assignment results in:
warning: large integer implicitly truncated to unsigned type [-Woverflow]
include/hw/register.h | 43 +++++++++++++++++++++++++++++++++++++++++++
1 file changed, 43 insertions(+)
diff --git a/include/hw/register.h b/include/hw/register.h
index e160150..216b679 100644
--- a/include/hw/register.h
+++ b/include/hw/register.h
@@ -150,4 +150,47 @@ void register_write_memory(void *opaque, hwaddr addr,
uint64_t value,
uint64_t register_read_memory(void *opaque, hwaddr addr, unsigned size);
+/* Define constants for a 32 bit register */
+
+/* This macro will define A_FOO, for the byte address of a register
+ * as well as R_FOO for the uint32_t[] register number (A_FOO / 4).
+ */
+#define REG32(reg, addr) \
+ enum { A_ ## reg = (addr) }; \
+ enum { R_ ## reg = (addr) / 4 };
+
+/* Define SHIFT, LEGTH and MASK constants for a field within a register */
+
+/* This macro will define FOO_BAR_MASK, FOO_BAR_SHIFT and FOO_BAR_LENGTH
+ * constants for field BAR in register FOO.
+ */
+#define FIELD(reg, field, shift, length) \
+ enum { R_ ## reg ## _ ## field ## _SHIFT = (shift)}; \
+ enum { R_ ## reg ## _ ## field ## _LENGTH = (length)}; \
+ enum { R_ ## reg ## _ ## field ## _MASK = \
+ MAKE_64BIT_MASK(shift, length);
+
+/* Extract a field from a register */
+#define FIELD_EX32(storage, reg, field) \
+ extract32((storage), R_ ## reg ## _ ## field ## _SHIFT, \
+ R_ ## reg ## _ ## field ## _LENGTH)
+
+/* Extract a field from an array of registers */
+#define ARRAY_FIELD_EX32(regs, reg, field) \
+ FIELD_EX32((regs)[R_ ## reg], reg, field)
+
+/* Deposit a register field. */
+#define FIELD_DP32(storage, reg, field, val) ({ \
+ struct { \
+ unsigned int v:R_ ## reg ## _ ## field ## _LENGTH; \
+ } v = { .v = val }; \
+ uint32_t d; \
+ d = deposit32((storage), R_ ## reg ## _ ## field ## _SHIFT, \
+ R_ ## reg ## _ ## field ## _LENGTH, v.v); \
+ d; })
+
+/* Deposit a field to array of registers. */
+#define ARRAY_FIELD_DP32(regs, reg, field, val) \
+ (regs)[R_ ## reg] = FIELD_DP32((regs)[R_ ## reg], reg, field, val);
+
#endif
--
2.7.4
