subsys/fs/nvs: Use flash_get_parameters() to get erase value

Use new flash API call to obtain erase value instead of relaying on
hardcoded literals.

Signed-off-by: Dominik Ermel <dominik.ermel@nordicsemi.no>

include/fs/nvs.h

@@ -57,6 +57,7 @@ struct nvs_fs {
 
 	struct k_mutex nvs_lock;
 	struct device *flash_device;
+	const struct flash_parameters *flash_parameters;
 };
 
 /**

subsys/fs/nvs/nvs.c

@@ -66,7 +66,9 @@ static int nvs_flash_al_wrt(struct nvs_fs *fs, uint32_t addr, const void *data,
 	}
 	if (len) {
 		memcpy(buf, data8, len);
-		(void)memset(buf + len, 0xff, fs->write_block_size - len);
+		(void)memset(buf + len, fs->flash_parameters->erase_value,
+			fs->write_block_size - len);
+
 		rc = flash_write(fs->flash_device, offset, buf,
 				 fs->write_block_size);
 		if (rc) {
@@ -221,7 +223,8 @@ static int nvs_flash_erase_sector(struct nvs_fs *fs, uint32_t addr)
 	off_t offset;
 
 	addr &= ADDR_SECT_MASK;
-	rc = nvs_flash_cmp_const(fs, addr, 0xff, fs->sector_size);
+	rc = nvs_flash_cmp_const(fs, addr, fs->flash_parameters->erase_value,
+			fs->sector_size);
 	if (rc <= 0) {
 		/* flash error or empty sector */
 		return rc;
@@ -351,7 +354,7 @@ static int nvs_prev_ate(struct nvs_fs *fs, uint32_t *addr, struct nvs_ate *ate)
 		return rc;
 	}
 
-	rc = nvs_ate_cmp_const(&close_ate, 0xff);
+	rc = nvs_ate_cmp_const(&close_ate, fs->flash_parameters->erase_value);
 	/* at the end of filesystem */
 	if (!rc) {
 		*addr = fs->ate_wra;
@@ -460,7 +463,7 @@ static int nvs_gc(struct nvs_fs *fs)
 		return rc;
 	}
 
-	rc = nvs_ate_cmp_const(&close_ate, 0xff);
+	rc = nvs_ate_cmp_const(&close_ate, fs->flash_parameters->erase_value);
 	if (!rc) {
 		rc = nvs_flash_erase_sector(fs, sec_addr);
 		if (rc) {
@@ -545,6 +548,7 @@ static int nvs_startup(struct nvs_fs *fs)
 	 */
 	uint32_t addr = 0U;
 	uint16_t i, closed_sectors = 0;
+	uint8_t erase_value = fs->flash_parameters->erase_value;
 
 	k_mutex_lock(&fs->nvs_lock, K_FOREVER);
 
@@ -555,14 +559,14 @@ static int nvs_startup(struct nvs_fs *fs)
 	for (i = 0; i < fs->sector_count; i++) {
 		addr = (i << ADDR_SECT_SHIFT) +
 		       (uint16_t)(fs->sector_size - ate_size);
-		rc = nvs_flash_cmp_const(fs, addr, 0xff,
+		rc = nvs_flash_cmp_const(fs, addr, erase_value,
-					  sizeof(struct nvs_ate));
+					 sizeof(struct nvs_ate));
 		if (rc) {
 			/* closed sector */
 			closed_sectors++;
 			nvs_sector_advance(fs, &addr);
-			rc = nvs_flash_cmp_const(fs, addr, 0xff,
+			rc = nvs_flash_cmp_const(fs, addr, erase_value,
-						  sizeof(struct nvs_ate));
+						 sizeof(struct nvs_ate));
 			if (!rc) {
 				/* open sector */
 				break;
@@ -581,8 +585,8 @@ static int nvs_startup(struct nvs_fs *fs)
 		 * two sectors. Then we can only set it to the first sector if
 		 * the last sector contains no ate's. So we check this first
 		 */
-		rc = nvs_flash_cmp_const(fs, addr - ate_size, 0xff,
+		rc = nvs_flash_cmp_const(fs, addr - ate_size, erase_value,
-				  sizeof(struct nvs_ate));
+				sizeof(struct nvs_ate));
 		if (!rc) {
 			/* empty ate */
 			nvs_sector_advance(fs, &addr);
@@ -590,7 +594,7 @@ static int nvs_startup(struct nvs_fs *fs)
 	}
 
 	/* addr contains address of the last ate in the most recent sector
-	 * search for the first ate containing all 0xff
+	 * search for the first ate containing all cells erased.
 	 */
 	fs->ate_wra = addr - ate_size;
 	fs->data_wra = addr & ADDR_SECT_MASK;
@@ -601,7 +605,8 @@ static int nvs_startup(struct nvs_fs *fs)
 			goto end;
 		}
 
-		rc = nvs_ate_cmp_const(&last_ate, 0xff);
+		rc = nvs_ate_cmp_const(&last_ate, erase_value);
+
 		if (!rc) {
 			/* found ff empty location */
 			break;
@@ -630,7 +635,8 @@ static int nvs_startup(struct nvs_fs *fs)
 	while (fs->ate_wra > fs->data_wra) {
 		empty_len = fs->ate_wra - fs->data_wra;
 
-		rc = nvs_flash_cmp_const(fs, fs->data_wra, 0xff, empty_len);
+		rc = nvs_flash_cmp_const(fs, fs->data_wra, erase_value,
+				empty_len);
 		if (rc < 0) {
 			goto end;
 		}
@@ -647,7 +653,7 @@ static int nvs_startup(struct nvs_fs *fs)
 	 */
 	addr = fs->ate_wra & ADDR_SECT_MASK;
 	nvs_sector_advance(fs, &addr);
-	rc = nvs_flash_cmp_const(fs, addr, 0xff, fs->sector_size);
+	rc = nvs_flash_cmp_const(fs, addr, erase_value, fs->sector_size);
 	if (rc < 0) {
 		goto end;
 	}
@@ -706,6 +712,12 @@ int nvs_init(struct nvs_fs *fs, const char *dev_name)
 		return -ENXIO;
 	}
 
+	fs->flash_parameters = flash_get_parameters(fs->flash_device);
+	if (fs->flash_parameters == NULL) {
+		LOG_ERR("Could not obtain flash parameters");
+		return -EINVAL;
+	}
+
 	write_block_size = flash_get_write_block_size(fs->flash_device);
 
 	/* check that the write block size is supported */

tests/subsys/fs/nvs/boards/qemu_x86_ev_0x00.overlay

@@ -0,0 +1,9 @@
+/*
+ * Copyright (c) 2020 Nordic Semiconductor ASA
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+&sim_flash {
+	erase-value = < 0x00 >;
+};

tests/subsys/fs/nvs/testcase.yaml

@@ -1,3 +1,6 @@
 tests:
   filesystem.nvs:
     platform_whitelist: qemu_x86
+  filesystem.nvs_0x00:
+    extra_args: DTC_OVERLAY_FILE=boards/qemu_x86_ev_0x00.overlay
+    platform_whitelist: qemu_x86