[RFC v2] hw/registerfields: add `FIELDx_1CLEAR()` macro

[Wilfred Mallawa <wilfred.mallawa@opensource.wdc.com>]

From: Wilfred Mallawa <wilfred.mallawa@wdc.com>

Changes from V1:
	* Instead of needing all field bits to be set
	  we clear the field if any are set. If the field is
	  0/clear then no change. 

Adds a helper macro that implements the register `w1c`
functionality.

Ex:
  uint32_t data = FIELD32_1CLEAR(val, REG, FIELD);

If ANY bits of the specified `FIELD` is set
then the respective field is cleared and returned to `data`.

If the field is cleared (0), then no change and
val is returned.

Signed-off-by: Wilfred Mallawa <wilfred.mallawa@wdc.com>
---
 include/hw/registerfields.h | 22 ++++++++++++++++++++++
 1 file changed, 22 insertions(+)

diff --git a/include/hw/registerfields.h b/include/hw/registerfields.h
index 1330ca77de..4a6a228339 100644
--- a/include/hw/registerfields.h
+++ b/include/hw/registerfields.h
@@ -115,6 +115,28 @@
                   R_ ## reg ## _ ## field ## _LENGTH, _v.v);              \
     _d; })
 
+/*
+ * Clear the specified field in reg_val if
+ * any field bits are set, else no changes made. Implements
+ * single/multi-bit `w1c`
+ *
+ */
+#define FIELD8_1CLEAR(reg_val, reg, field)                                \
+    (FIELD_EX8(reg_val, reg, field) ?                                     \
+    FIELD_DP8(reg_val, reg, field, 0x00) : reg_val)
+
+#define FIELD16_1CLEAR(reg_val, reg, field)                               \
+    (FIELD_EX16(reg_val, reg, field) ?                                    \
+    FIELD_DP16(reg_val, reg, field, 0x00) : reg_val)
+
+#define FIELD32_1CLEAR(reg_val, reg, field)                               \
+    (FIELD_EX32(reg_val, reg, field) ?                                    \
+    FIELD_DP32(reg_val, reg, field, 0x00) : reg_val)
+
+#define FIELD64_1CLEAR(reg_val, reg, field)                               \
+    (FIELD_EX64(reg_val, reg, field) ?                                    \
+    FIELD_DP64(reg_val, reg, field, 0x00) : reg_val)
+
 #define FIELD_SDP8(storage, reg, field, val) ({                           \
     struct {                                                              \
         signed int v:R_ ## reg ## _ ## field ## _LENGTH;                  \
-- 
2.37.3