tree/: Convert flashchip decode range func ptr to enum

Replace the `decode_range` function pointer in `struct flashchip` to an
enum value. The enum value can be used to find the corresponding
function pointer by passing it to `lookup_decode_range_func_ptr()`.

Removing function pointers like `decode_range` makes it possible to represent chip data in a declarative format that does not have to be
stored as C source code.

BUG=b:242479049
BRANCH=none
TEST=ninja && ninja test

Signed-off-by: Nikolai Artemiev <nartemiev@google.com>
Change-Id: If6d08d414d3d1ddadc95ca1d407fc87c23ab543d
Reviewed-on: https://review.coreboot.org/c/flashrom/+/67195
Reviewed-by: Edward O'Callaghan <quasisec@chromium.org>
Reviewed-by: Felix Singer <felixsinger@posteo.net>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

4 files changed, 51 insertions, 28 deletions

diff --git a/flashchips.c b/flashchips.c
index 41e4c42c2..cbfbc7b15 100644
--- a/flashchips.c
+++ b/flashchips.c
@@ -2451,7 +2451,7 @@ const struct flashchip flashchips[] = {
 			.sec    = {STATUS1, 6, RW},
 			.cmp    = {STATUS2, 6, RW},
 		},
-		.decode_range	= decode_range_spi25,
+		.decode_range	= DECODE_RANGE_SPI25,
 	},
 
 	{
@@ -5183,7 +5183,7 @@ const struct flashchip flashchips[] = {
 			.bp     = {{STATUS1, 2, RW}, {STATUS1, 3, RW}, {STATUS1, 4, RW}},
 			.tb     = {STATUS1, 5, RW}, /* Called BP3 in datasheet, acts like TB */
 		},
-		.decode_range	= decode_range_spi25,
+		.decode_range	= DECODE_RANGE_SPI25,
 	},
 
 	{
@@ -6371,7 +6371,7 @@ const struct flashchip flashchips[] = {
 			.sec    = {STATUS1, 6, RW}, /* Called BP4 in datasheet, acts like SEC */
 			.cmp    = {STATUS2, 6, RW},
 		},
-		.decode_range	= decode_range_spi25,
+		.decode_range	= DECODE_RANGE_SPI25,
 	},
 
 	{
@@ -6537,7 +6537,7 @@ const struct flashchip flashchips[] = {
 			.sec    = {STATUS1, 6, RW}, /* Called BP4 in datasheet, acts like SEC */
 			.cmp    = {STATUS2, 6, RW},
 		},
-		.decode_range	= decode_range_spi25,
+		.decode_range	= DECODE_RANGE_SPI25,
 	},
 
 	{
@@ -6665,7 +6665,7 @@ const struct flashchip flashchips[] = {
 			.sec    = {STATUS1, 6, RW}, /* Called BP4 in datasheet, acts like SEC */
 			.cmp    = {STATUS2, 6, RW},
 		},
-		.decode_range	= decode_range_spi25,
+		.decode_range	= DECODE_RANGE_SPI25,
 	},
 
 	{
@@ -6798,7 +6798,7 @@ const struct flashchip flashchips[] = {
 			.bp     = {{STATUS1, 2, RW}, {STATUS1, 3, RW}, {STATUS1, 4, RW}, {STATUS1, 5, RW}},
 			.tb     = {STATUS1, 6, RW},
 		},
-		.decode_range	= decode_range_spi25,
+		.decode_range	= DECODE_RANGE_SPI25,
 	},
 
 	{
@@ -6847,7 +6847,7 @@ const struct flashchip flashchips[] = {
 			.sec    = {STATUS1, 6, RW}, /* Called BP4 in datasheet, acts like SEC */
 			.cmp    = {STATUS2, 6, RW},
 		},
-		.decode_range	= decode_range_spi25,
+		.decode_range	= DECODE_RANGE_SPI25,
 	},
 
 	{
@@ -6969,7 +6969,7 @@ const struct flashchip flashchips[] = {
 			.sec    = {STATUS1, 6, RW}, /* Called BP4 in datasheet, acts like SEC */
 			.cmp    = {STATUS2, 6, RW},
 		},
-		.decode_range	= decode_range_spi25,
+		.decode_range	= DECODE_RANGE_SPI25,
 	},
 
 	{
@@ -16236,7 +16236,7 @@ const struct flashchip flashchips[] = {
 			.cmp	= {STATUS2, 6, RW},
 			.wps	= {STATUS3, 2, RW},
 		},
-		.decode_range	= decode_range_spi25,
+		.decode_range	= DECODE_RANGE_SPI25,
 	},
 
 	{
@@ -16729,7 +16729,7 @@ const struct flashchip flashchips[] = {
 			.cmp	= {STATUS2, 6, RW},
 			.wps	= {STATUS3, 2, RW},
 		},
-		.decode_range	= decode_range_spi25,
+		.decode_range	= DECODE_RANGE_SPI25,
 	},
 
 	{
@@ -17347,7 +17347,7 @@ const struct flashchip flashchips[] = {
 			.cmp	= {STATUS2, 6, RW},
 			.wps	= {STATUS3, 2, RW},
 		},
-		.decode_range	= decode_range_spi25,
+		.decode_range	= DECODE_RANGE_SPI25,
 	},
 
 	{
@@ -17395,7 +17395,7 @@ const struct flashchip flashchips[] = {
 			.sec    = {STATUS1, 6, RW},
 			.cmp    = {STATUS2, 6, RW},
 		},
-		.decode_range	= decode_range_spi25,
+		.decode_range	= DECODE_RANGE_SPI25,
 	},
 
 	{
@@ -17445,7 +17445,7 @@ const struct flashchip flashchips[] = {
 			.sec    = {STATUS1, 6, RW},
 			.cmp    = {STATUS2, 6, RW},
 		},
-		.decode_range	= decode_range_spi25,
+		.decode_range	= DECODE_RANGE_SPI25,
 	},
 
 	{
@@ -17493,7 +17493,7 @@ const struct flashchip flashchips[] = {
 			.sec    = {STATUS1, 6, RW},
 			.cmp    = {STATUS2, 6, RW},
 		},
-		.decode_range	= decode_range_spi25,
+		.decode_range	= DECODE_RANGE_SPI25,
 	},
 
 	{
@@ -17663,7 +17663,7 @@ const struct flashchip flashchips[] = {
 			.tb     = {STATUS1, 6, RW},
 			.cmp    = {STATUS2, 6, RW},
 		},
-		.decode_range	= decode_range_spi25,
+		.decode_range	= DECODE_RANGE_SPI25,
 	},
 
 	{
@@ -17718,7 +17718,7 @@ const struct flashchip flashchips[] = {
 			.tb     = {STATUS1, 6, RW},
 			.cmp    = {STATUS2, 6, RW},
 		},
-		.decode_range	= decode_range_spi25,
+		.decode_range	= DECODE_RANGE_SPI25,
 	},
 
 	{
@@ -17773,7 +17773,7 @@ const struct flashchip flashchips[] = {
 			.tb     = {STATUS1, 6, RW},
 			.cmp    = {STATUS2, 6, RW},
 		},
-		.decode_range	= decode_range_spi25,
+		.decode_range	= DECODE_RANGE_SPI25,
 	},
 
 	{
@@ -18238,7 +18238,7 @@ const struct flashchip flashchips[] = {
 			.sec	= {STATUS1, 6, RW},
 			.cmp	= {STATUS2, 6, RW},
 		},
-		.decode_range	= decode_range_spi25,
+		.decode_range	= DECODE_RANGE_SPI25,
 	},
 
 	{
@@ -18290,7 +18290,7 @@ const struct flashchip flashchips[] = {
 			.cmp	= {STATUS2, 6, RW},
 			.wps	= {STATUS3, 2, RW},
 		},
-		.decode_range	= decode_range_spi25,
+		.decode_range	= DECODE_RANGE_SPI25,
 	},
 
 	{
@@ -18380,7 +18380,7 @@ const struct flashchip flashchips[] = {
 			.sec    = {STATUS1, 6, RW},
 			.cmp    = {STATUS2, 6, RW},
 		},
-		.decode_range	= decode_range_spi25,
+		.decode_range	= DECODE_RANGE_SPI25,
 	},
 
 	{
@@ -19752,7 +19752,7 @@ const struct flashchip flashchips[] = {
 			.sec    = {STATUS1, 6, RW},
 			.cmp    = {STATUS2, 6, RW},
 		},
-		.decode_range	= decode_range_spi25,
+		.decode_range	= DECODE_RANGE_SPI25,
 	},
 
 	{
@@ -19842,7 +19842,7 @@ const struct flashchip flashchips[] = {
 			.bp     = {{STATUS1, 2, RW}, {STATUS1, 3, RW}, {STATUS1, 4, RW}, {STATUS1, 5, RW}},
 			.tb     = {STATUS1, 6, RW},
 		},
-		.decode_range	= decode_range_spi25,
+		.decode_range	= DECODE_RANGE_SPI25,
 	},
 
 	{
diff --git a/include/flash.h b/include/flash.h
index 633601db8..32290e4d4 100644
--- a/include/flash.h
+++ b/include/flash.h
@@ -211,6 +211,12 @@ struct reg_bit_info {
 
 struct wp_bits;
 
+enum decode_range_func {
+	NO_DECODE_RANGE_FUNC = 0, /* 0 indicates no range decode funciton is set. */
+	DECODE_RANGE_SPI25 = 1,
+};
+typedef void (decode_range_func_t)(size_t *start, size_t *len, const struct wp_bits *, size_t chip_len);
+
 struct flashchip {
 	const char *vendor;
 	const char *name;
@@ -321,9 +327,11 @@ struct flashchip {
 		struct reg_bit_info wps;
 	} reg_bits;
 
-	/* Function that takes a set of WP config bits (e.g. BP, SEC, TB, etc) */
-	/* and determines what protection range they select. */
-	void (*decode_range)(size_t *start, size_t *len, const struct wp_bits *, size_t chip_len);
+	/*
+	 * Function that takes a set of WP config bits (e.g. BP, SEC, TB, etc)
+	 * and determines what protection range they select.
+	 */
+	enum decode_range_func decode_range;
 };
 
 typedef int (*chip_restore_fn_cb_t)(struct flashctx *flash, uint8_t status);
diff --git a/tests/chip_wp.c b/tests/chip_wp.c
index 95e6b05ce..e4eff9907 100644
--- a/tests/chip_wp.c
+++ b/tests/chip_wp.c
@@ -97,7 +97,7 @@ static const struct flashchip chip_W25Q128_V = {
 		.cmp    = {STATUS2, 6, RW},
 		.wps    = {STATUS3, 2, RW},
 	},
-	.decode_range	= decode_range_spi25,
+	.decode_range	= DECODE_RANGE_SPI25,
 };
 
 /* Trying to set an unsupported WP range fails */
diff --git a/writeprotect.c b/writeprotect.c
index 57d0f9bd6..dcffe0308 100644
--- a/writeprotect.c
+++ b/writeprotect.c
@@ -174,11 +174,26 @@ static enum flashrom_wp_result write_wp_bits(struct flashctx *flash, struct wp_b
 	return FLASHROM_WP_OK;
 }
 
+static decode_range_func_t *lookup_decode_range_func_ptr(const struct flashchip *chip)
+{
+	switch (chip->decode_range) {
+		case DECODE_RANGE_SPI25: return &decode_range_spi25;
+	/* default: total function, 0 indicates no decode range function set. */
+		case NO_DECODE_RANGE_FUNC: return NULL;
+	};
+
+	return NULL;
+}
+
+
 /** Get the range selected by a WP configuration. */
 static enum flashrom_wp_result get_wp_range(struct wp_range *range, struct flashctx *flash, const struct wp_bits *bits)
 {
-	flash->chip->decode_range(&range->start, &range->len, bits, flashrom_flash_getsize(flash));
+	decode_range_func_t *decode_range = lookup_decode_range_func_ptr(flash->chip);
+	if (decode_range == NULL)
+		return FLASHROM_WP_ERR_OTHER;
 
+	decode_range(&range->start, &range->len, bits, flashrom_flash_getsize(flash));
 	return FLASHROM_WP_OK;
 }
 
@@ -424,7 +439,7 @@ static int set_wp_mode(struct wp_bits *bits, const enum flashrom_wp_mode mode)
 
 static bool chip_supported(struct flashctx *flash)
 {
-	return (flash->chip != NULL) && (flash->chip->decode_range != NULL);
+	return (flash->chip != NULL) && (flash->chip->decode_range != NO_DECODE_RANGE_FUNC);
 }