[PATCH] arm64/sysreg: allow *Enum blocks in SysregFields blocks

[Mark Rutland]

We'd like to support Enum/SignedEnum/UnsignedEnum blocks within
SysregFields blocks, so that we can define enumerations for sets of
registers. This isn't currently supported by gen-sysreg.awk due to the
way we track the active block, which can't handle more than a single
layer of nesting, which imposes an awkward requirement that when ending
a block we know what the parent block is when calling change_block()

Make this nicer by using a stack of active blocks, with block_push() to
start a block, and block_pop() to end a block. Doing so means hat when
ending a block we don't need to know the parent block type, and checks
of the active block become more consistent. On top of that, it's easy to
permit *Enum blocks within both Sysreg and SysregFields blocks.

To aid debugging, the stack of active blocks is reported for fatal
errors, and an error is raised if the file is terminated without ending
the active block. For clarity I've renamed the top-level element from
"None" to "Root".

The Fields element it intended only for use within Systeg blocks, and
does not make sense within SysregFields blocks, and so remains forbidden
within a SysregFields block.

Signed-off-by: Mark Rutland <mark.rutland@xxxxxxx>
Cc: Anshuman Khandual <anshuman.khandual@xxxxxxx>
Cc: Catalin Marinas <catalin.marinas@xxxxxxx>
Cc: Mark Brown <broonie@xxxxxxxxxx>
Cc: Will Deacon <will@xxxxxxxxxx>
---
 arch/arm64/tools/gen-sysreg.awk | 93 ++++++++++++++++++++-------------
 1 file changed, 57 insertions(+), 36 deletions(-)

diff --git a/arch/arm64/tools/gen-sysreg.awk b/arch/arm64/tools/gen-sysreg.awk
index 7f27d66a17e1..066ebf5410fa 100755
--- a/arch/arm64/tools/gen-sysreg.awk
+++ b/arch/arm64/tools/gen-sysreg.awk
@@ -4,23 +4,35 @@
 #
 # Usage: awk -f gen-sysreg.awk sysregs.txt
 
+function block_current() {
+	return __current_block[__current_block_depth];
+}
+
 # Log an error and terminate
 function fatal(msg) {
 	print "Error at " NR ": " msg > "/dev/stderr"
+
+	printf "Current block nesting:"
+
+	for (i = 0; i <= __current_block_depth; i++) {
+		printf " " __current_block[i]
+	}
+	printf "\n"
+
 	exit 1
 }
 
-# Sanity check that the start or end of a block makes sense at this point in
-# the file. If not, produce an error and terminate.
-#
-# @this - the $Block or $EndBlock
-# @prev - the only valid block to already be in (value of @block)
-# @new - the new value of @block
-function change_block(this, prev, new) {
-	if (block != prev)
-		fatal("unexpected " this " (inside " block ")")
-
-	block = new
+# Enter a new block, setting the active block to @block
+function block_push(block) {
+	__current_block[++__current_block_depth] = block
+}
+
+# Exit a block, setting the active block to the parent block
+function block_pop() {
+	if (__current_block_depth == 0)
+		fatal("error: block_pop() in root block")
+
+	__current_block_depth--;
 }
 
 # Sanity check the number of records for a field makes sense. If not, produce
@@ -84,10 +96,14 @@ BEGIN {
 	print "/* Generated file - do not edit */"
 	print ""
 
-	block = "None"
+	__current_block_depth = 0
+	__current_block[__current_block_depth] = "Root"
 }
 
 END {
+	if (__current_block_depth != 0)
+		fatal("Missing terminator for " block_current() " block")
+
 	print "#endif /* __ASM_SYSREG_DEFS_H */"
 }
 
@@ -95,8 +111,9 @@ END {
 /^$/ { next }
 /^[\t ]*#/ { next }
 
-/^SysregFields/ {
-	change_block("SysregFields", "None", "SysregFields")
+/^SysregFields/ && block_current() == "Root" {
+	block_push("SysregFields")
+
 	expect_fields(2)
 
 	reg = $2
@@ -109,12 +126,10 @@ END {
 	next
 }
 
-/^EndSysregFields/ {
+/^EndSysregFields/ && block_current() == "SysregFields" {
 	if (next_bit > 0)
 		fatal("Unspecified bits in " reg)
 
-	change_block("EndSysregFields", "SysregFields", "None")
-
 	define(reg "_RES0", "(" res0 ")")
 	define(reg "_RES1", "(" res1 ")")
 	print ""
@@ -123,11 +138,13 @@ END {
 	res0 = null
 	res1 = null
 
+	block_pop()
 	next
 }
 
-/^Sysreg/ {
-	change_block("Sysreg", "None", "Sysreg")
+/^Sysreg/ && block_current() == "Root" {
+	block_push("Sysreg")
+
 	expect_fields(7)
 
 	reg = $2
@@ -156,12 +173,10 @@ END {
 	next
 }
 
-/^EndSysreg/ {
+/^EndSysreg/ && block_current() == "Sysreg" {
 	if (next_bit > 0)
 		fatal("Unspecified bits in " reg)
 
-	change_block("EndSysreg", "Sysreg", "None")
-
 	if (res0 != null)
 		define(reg "_RES0", "(" res0 ")")
 	if (res1 != null)
@@ -178,12 +193,13 @@ END {
 	res0 = null
 	res1 = null
 
+	block_pop()
 	next
 }
 
 # Currently this is effectivey a comment, in future we may want to emit
 # defines for the fields.
-/^Fields/ && (block == "Sysreg") {
+/^Fields/ && block_current() == "Sysreg" {
 	expect_fields(2)
 
 	if (next_bit != 63)
@@ -200,7 +216,7 @@ END {
 }
 
 
-/^Res0/ && (block == "Sysreg" || block == "SysregFields") {
+/^Res0/ && (block_current() == "Sysreg" || block_current() == "SysregFields") {
 	expect_fields(2)
 	parse_bitdef(reg, "RES0", $2)
 	field = "RES0_" msb "_" lsb
@@ -210,7 +226,7 @@ END {
 	next
 }
 
-/^Res1/ && (block == "Sysreg" || block == "SysregFields") {
+/^Res1/ && (block_current() == "Sysreg" || block_current() == "SysregFields") {
 	expect_fields(2)
 	parse_bitdef(reg, "RES1", $2)
 	field = "RES1_" msb "_" lsb
@@ -220,7 +236,7 @@ END {
 	next
 }
 
-/^Field/ && (block == "Sysreg" || block == "SysregFields") {
+/^Field/ && (block_current() == "Sysreg" || block_current() == "SysregFields") {
 	expect_fields(3)
 	field = $3
 	parse_bitdef(reg, field, $2)
@@ -231,15 +247,16 @@ END {
 	next
 }
 
-/^Raz/ && (block == "Sysreg" || block == "SysregFields") {
+/^Raz/ && (block_current() == "Sysreg" || block_current() == "SysregFields") {
 	expect_fields(2)
 	parse_bitdef(reg, field, $2)
 
 	next
 }
 
-/^SignedEnum/ {
-	change_block("Enum<", "Sysreg", "Enum")
+/^SignedEnum/ && (block_current() == "Sysreg" || block_current() == "SysregFields") {
+	block_push("Enum")
+
 	expect_fields(3)
 	field = $3
 	parse_bitdef(reg, field, $2)
@@ -250,8 +267,9 @@ END {
 	next
 }
 
-/^UnsignedEnum/ {
-	change_block("Enum<", "Sysreg", "Enum")
+/^UnsignedEnum/ && (block_current() == "Sysreg" || block_current() == "SysregFields") {
+	block_push("Enum")
+
 	expect_fields(3)
 	field = $3
 	parse_bitdef(reg, field, $2)
@@ -262,8 +280,9 @@ END {
 	next
 }
 
-/^Enum/ {
-	change_block("Enum", "Sysreg", "Enum")
+/^Enum/ && (block_current() == "Sysreg" || block_current() == "SysregFields") {
+	block_push("Enum")
+
 	expect_fields(3)
 	field = $3
 	parse_bitdef(reg, field, $2)
@@ -273,16 +292,18 @@ END {
 	next
 }
 
-/^EndEnum/ {
-	change_block("EndEnum", "Enum", "Sysreg")
+/^EndEnum/ && block_current() == "Enum" {
+
 	field = null
 	msb = null
 	lsb = null
 	print ""
+
+	block_pop()
 	next
 }
 
-/0b[01]+/ && block == "Enum" {
+/0b[01]+/ && block_current() == "Enum" {
 	expect_fields(2)
 	val = $1
 	name = $2
-- 
2.30.2