Fix FEATURE_NO_ERASE chips and add test for them

New check was added to `check_block_eraser` in
commit 0f389aea9e630c3b21547a5dd8dbe572a8502853 but it was not
handling FEATURE_NO_ERASE chips.

This patch fixes processing such chips and adds test to run
write and verify with dummyflasher for FEATURE_NO_ERASE chips.

Ticket: https://ticket.coreboot.org/issues/553

Change-Id: I582fe00da0715e9b5e92fcc9d15d5a90a2615117
Signed-off-by: Anastasia Klimchuk <aklm@flashrom.org>
Reviewed-on: https://review.coreboot.org/c/flashrom/+/84203
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Peter Marheine <pmarheine@chromium.org>

flashrom.c

@@ -484,14 +484,15 @@ int check_block_eraser(const struct flashctx *flash, int k, int log)
 
 	if (flash->mst->buses_supported & BUS_SPI) {
 		const uint8_t *opcode = spi_get_opcode_from_erasefn(eraser.block_erase);
-		for (int i = 0; opcode[i]; i++) {
-			if (!spi_probe_opcode(flash, opcode[i])) {
-				if (log)
-					msg_cdbg("block erase function and layout found "
-						 "but SPI master doesn't support the function. ");
-				return 1;
+		if (opcode)
+			for (int i = 0; opcode[i]; i++) {
+				if (!spi_probe_opcode(flash, opcode[i])) {
+					if (log)
+						msg_cdbg("block erase function and layout found "
+							 "but SPI master doesn't support the function. ");
+					return 1;
+				}
 			}
-		}
 	}
 	// TODO: Once erase functions are annotated with allowed buses, check that as well.
 	return 0;

include/flash.h

@@ -148,6 +148,14 @@ enum write_granularity {
  * other flash chips, such as the ENE KB9012 internal flash, work the opposite way.
  */
 #define FEATURE_ERASED_ZERO	(1 << 18)
+/*
+ * Feature indicates that the chip does not require erase before writing:
+ * write operations can set any bit to any value without first doing an erase,
+ * but bulk erase operations may still be supported.
+ *
+ * EEPROMs usually behave this way (compare to Flash, which requires erase),
+ * for example the ST M95M02.
+ */
 #define FEATURE_NO_ERASE	(1 << 19)
 
 #define FEATURE_WRSR_EXT2	(1 << 20)

tests/chip.c

@@ -27,6 +27,7 @@
 
 #include <include/test.h>
 #include <stdio.h>
+#include <stdlib.h>
 #include <string.h>
 
 #include "tests.h"
@@ -132,6 +133,25 @@ static const struct flashchip chip_8MiB = {
 	 }},
 };
 
+/* Chip expected to be processed with dummyflasher, so using real op functions. */
+static const struct flashchip chip_no_erase = {
+	.vendor		= "aklm&dummyflasher",
+	.total_size	= 16 * 1024,
+	.tested		= TEST_OK_PREW,
+	.read		= SPI_CHIP_READ,
+	.write		= SPI_CHIP_WRITE256,
+	.page_size	= 256,
+	.feature_bits   = FEATURE_NO_ERASE | FEATURE_ERASED_ZERO,
+	.block_erasers  =
+	{
+		{
+			.eraseblocks = { {16 * 1024 * 1024, 1} },
+			/* Special erase fn for chips without erase capability. */
+			.block_erase = SPI_BLOCK_ERASE_EMULATION,
+		}
+	},
+};
+
 /* Setup the struct for W25Q128.V, all values come from flashchips.c */
 static const struct flashchip chip_W25Q128_V = {
 	.vendor		= "aklm&dummyflasher",
@@ -384,6 +404,48 @@ void write_chip_with_dummyflasher_test_success(void **state)
 	free(newcontents);
 }
 
+void write_chip_feature_no_erase(void **state)
+{
+	(void) state; /* unused */
+
+	static struct io_mock_fallback_open_state data = {
+		.noc	= 0,
+		.paths	= { NULL },
+	};
+	const struct io_mock chip_io = {
+		.fallback_open_state = &data,
+	};
+
+	struct flashrom_flashctx flashctx = { 0 };
+	struct flashrom_layout *layout;
+
+	/*
+	 * Tricking the dummyflasher by asking to emulate W25Q128FV but giving to it
+	 * mock chip with FEATURE_NO_ERASE.
+	 * As long as chip size is the same, this is fine.
+	 */
+	struct flashchip mock_chip = chip_no_erase;
+	const char *param_dup = "bus=spi,emulate=W25Q128FV";
+
+	setup_chip(&flashctx, &layout, &mock_chip, param_dup, &chip_io);
+
+	/* See comment in write_chip_test_success */
+	const char *const filename = "-";
+	unsigned long size = mock_chip.total_size * 1024;
+	uint8_t *const newcontents = malloc(size);
+	assert_non_null(newcontents);
+
+	printf("Write chip operation started.\n");
+	assert_int_equal(0, read_buf_from_file(newcontents, size, filename));
+	assert_int_equal(0, flashrom_image_write(&flashctx, newcontents, size, NULL));
+	assert_int_equal(0, flashrom_image_verify(&flashctx, newcontents, size));
+	printf("Write chip operation done.\n");
+
+	teardown(&layout);
+
+	free(newcontents);
+}
+
 void write_nonaligned_region_with_dummyflasher_test_success(void **state)
 {
 	(void) state; /* unused */

tests/tests.c

@@ -498,6 +498,7 @@ int main(int argc, char *argv[])
 		cmocka_unit_test(read_chip_with_dummyflasher_test_success),
 		cmocka_unit_test(write_chip_test_success),
 		cmocka_unit_test(write_chip_with_dummyflasher_test_success),
+		cmocka_unit_test(write_chip_feature_no_erase),
 		cmocka_unit_test(write_nonaligned_region_with_dummyflasher_test_success),
 		cmocka_unit_test(verify_chip_test_success),
 		cmocka_unit_test(verify_chip_with_dummyflasher_test_success),

tests/tests.h

@@ -86,6 +86,7 @@ void read_chip_test_success(void **state);
 void read_chip_with_dummyflasher_test_success(void **state);
 void write_chip_test_success(void **state);
 void write_chip_with_dummyflasher_test_success(void **state);
+void write_chip_feature_no_erase(void **state);
 void write_nonaligned_region_with_dummyflasher_test_success(void **state);
 void verify_chip_test_success(void **state);
 void verify_chip_with_dummyflasher_test_success(void **state);