tree/: Convert flashchip read func ptr to enumerate

This forges the way for flashchips.c to be pure declarative
data and lookup functions for dispatch to be pure. This
means that the flashchips data could be extracted out to
be agnostic data of the flashrom code and algorithms.

TEST='R|W|E && --flash-name' on ARM, AMD & Intel DUT's.

Change-Id: I612d46fefedf2b69e7e2064aa857fa0756efb4e7
Signed-off-by: Edward O'Callaghan <quasisec@google.com>
Reviewed-on: https://review.coreboot.org/c/flashrom/+/66788
Reviewed-by: Nikolai Artemiev <nartemiev@google.com>
Reviewed-by: Felix Singer <felixsinger@posteo.net>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

1 files changed, 40 insertions, 11 deletions

diff --git a/flashrom.c b/flashrom.c
index 3ddc4b03c..694e2c5ed 100644
--- a/flashrom.c
+++ b/flashrom.c
@@ -411,6 +411,35 @@ static int check_erased_range(struct flashctx *flash, unsigned int start, unsign
 	return ret;
 }
 
+/* special unit-test hook */
+read_func_t *g_test_read_injector;
+
+static read_func_t *lookup_read_func_ptr(const struct flashchip *chip)
+{
+	switch (chip->read) {
+		case SPI_CHIP_READ: return &spi_chip_read;
+		case READ_OPAQUE: return &read_opaque;
+		case READ_MEMMAPPED: return &read_memmapped;
+		case EDI_CHIP_READ: return &edi_chip_read;
+		case SPI_READ_AT45DB: return spi_read_at45db;
+		case SPI_READ_AT45DB_E8: return spi_read_at45db_e8;
+		case TEST_READ_INJECTOR: return g_test_read_injector;
+	/* default: total function, 0 indicates no read function set.
+	 * We explicitly do not want a default catch-all case in the switch
+	 * to ensure unhandled enum's are compiler warnings.
+	 */
+		case NO_READ_FUNC: return NULL;
+	};
+
+	return NULL;
+}
+
+int read_flash(struct flashctx *flash, uint8_t *buf, unsigned int start, unsigned int len)
+{
+	read_func_t *read_func = lookup_read_func_ptr(flash->chip);
+	return read_func(flash, buf, start, len);
+}
+
 /*
  * @cmpbuf	buffer to compare against, cmpbuf[0] is expected to match the
  *		flash content at location start
@@ -430,7 +459,7 @@ int verify_range(struct flashctx *flash, const uint8_t *cmpbuf, unsigned int sta
 		return -1;
 	}
 
-	if (!flash->chip->read) {
+	if (!lookup_read_func_ptr(flash->chip)) {
 		msg_cerr("ERROR: flashrom has no read function for this flash chip.\n");
 		return -1;
 	}
@@ -441,7 +470,7 @@ int verify_range(struct flashctx *flash, const uint8_t *cmpbuf, unsigned int sta
 		return -1;
 	}
 
-	int ret = flash->chip->read(flash, readbuf, start, len);
+	int ret = read_flash(flash, readbuf, start, len);
 	if (ret) {
 		msg_gerr("Verification impossible because read failed "
 			 "at 0x%x (len 0x%x)\n", start, len);
@@ -930,7 +959,7 @@ static int read_by_layout(struct flashctx *const flashctx, uint8_t *const buffer
 		const chipoff_t region_start	= entry->start;
 		const chipsize_t region_len	= entry->end - entry->start + 1;
 
-		if (flashctx->chip->read(flashctx, buffer + region_start, region_start, region_len))
+		if (read_flash(flashctx, buffer + region_start, region_start, region_len))
 			return 1;
 	}
 	return 0;
@@ -1159,7 +1188,7 @@ static int erase_block(struct flashctx *const flashctx,
 		if (info->region_start > info->erase_start) {
 			const chipoff_t start	= info->erase_start;
 			const chipsize_t len	= info->region_start - info->erase_start;
-			if (flashctx->chip->read(flashctx, backup_contents, start, len)) {
+			if (read_flash(flashctx, backup_contents, start, len)) {
 				msg_cerr("Can't read! Aborting.\n");
 				goto _free_ret;
 			}
@@ -1169,7 +1198,7 @@ static int erase_block(struct flashctx *const flashctx,
 			const chipoff_t start     = info->region_end + 1;
 			const chipoff_t rel_start = start - info->erase_start; /* within this erase block */
 			const chipsize_t len      = info->erase_end - info->region_end;
-			if (flashctx->chip->read(flashctx, backup_contents + rel_start, start, len)) {
+			if (read_flash(flashctx, backup_contents + rel_start, start, len)) {
 				msg_cerr("Can't read! Aborting.\n");
 				goto _free_ret;
 			}
@@ -1256,7 +1285,7 @@ static int read_erase_write_block(struct flashctx *const flashctx,
 		if (info->region_start > info->erase_start) {
 			const chipoff_t start	= info->erase_start;
 			const chipsize_t len	= info->region_start - info->erase_start;
-			if (flashctx->chip->read(flashctx, newc, start, len)) {
+			if (read_flash(flashctx, newc, start, len)) {
 				msg_cerr("Can't read! Aborting.\n");
 				goto _free_ret;
 			}
@@ -1267,7 +1296,7 @@ static int read_erase_write_block(struct flashctx *const flashctx,
 			const chipoff_t start     = info->region_end + 1;
 			const chipoff_t rel_start = start - info->erase_start; /* within this erase block */
 			const chipsize_t len      = info->erase_end - info->region_end;
-			if (flashctx->chip->read(flashctx, newc + rel_start, start, len)) {
+			if (read_flash(flashctx, newc + rel_start, start, len)) {
 				msg_cerr("Can't read! Aborting.\n");
 				goto _free_ret;
 			}
@@ -1367,7 +1396,7 @@ static int verify_by_layout(
 		const chipoff_t region_start	= entry->start;
 		const chipsize_t region_len	= entry->end - entry->start + 1;
 
-		if (flashctx->chip->read(flashctx, curcontents + region_start, region_start, region_len))
+		if (read_flash(flashctx, curcontents + region_start, region_start, region_len))
 			return 1;
 		if (compare_range(newcontents + region_start, curcontents + region_start,
 				  region_start, region_len))
@@ -1554,7 +1583,7 @@ static int chip_safety_check(const struct flashctx *flash, int force,
 				return 1;
 			msg_cerr("Continuing anyway.\n");
 		}
-		if (!chip->read) {
+		if (!lookup_read_func_ptr(chip)) {
 			msg_cerr("flashrom has no read function for this "
 				 "flash chip.\n");
 			return 1;
@@ -1775,7 +1804,7 @@ int flashrom_image_write(struct flashctx *const flashctx, void *const buffer, co
 		 */
 		msg_cinfo("Reading old flash chip contents... ");
 		if (verify_all) {
-			if (flashctx->chip->read(flashctx, oldcontents, 0, flash_size)) {
+			if (read_flash(flashctx, oldcontents, 0, flash_size)) {
 				msg_cinfo("FAILED.\n");
 				goto _finalize_ret;
 			}
@@ -1795,7 +1824,7 @@ int flashrom_image_write(struct flashctx *const flashctx, void *const buffer, co
 		if (verify_all) {
 			msg_cerr("Checking if anything has changed.\n");
 			msg_cinfo("Reading current flash chip contents... ");
-			if (!flashctx->chip->read(flashctx, curcontents, 0, flash_size)) {
+			if (!read_flash(flashctx, curcontents, 0, flash_size)) {
 				msg_cinfo("done.\n");
 				if (!memcmp(oldcontents, curcontents, flash_size)) {
 					nonfatal_help_message();