storeage/stream_flash: Cache write_block_size to ctx on init

The commit caches write_block_size and erase_value to stream flash
context, at init, to avoid calling Flash API multiple times
to get these values at various stages of code exectuion,
at run-time.

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

include/zephyr/storage/stream_flash.h

@@ -65,6 +65,8 @@ struct stream_flash_ctx {
 #ifdef CONFIG_STREAM_FLASH_ERASE
 	off_t last_erased_page_start_offset; /* Last erased offset */
 #endif
+	uint8_t erase_value;
+	uint8_t write_block_size;	/* Offset/size device write alignment */
 };
 
 /**

subsys/storage/stream/stream_flash.c

@@ -128,10 +128,10 @@ static int flash_sync(struct stream_flash_ctx *ctx)
 		}
 	}
 
-	fill_length = flash_get_write_block_size(ctx->fdev);
+	fill_length = ctx->write_block_size;
 	if (ctx->buf_bytes % fill_length) {
 		fill_length -= ctx->buf_bytes % fill_length;
-		filler = flash_get_parameters(ctx->fdev)->erase_value;
+		filler = ctx->erase_value;
 
 		memset(ctx->buf + ctx->buf_bytes, filler, fill_length);
 	} else {
@@ -249,6 +249,7 @@ int stream_flash_init(struct stream_flash_ctx *ctx, const struct device *fdev,
 		      uint8_t *buf, size_t buf_len, size_t offset, size_t size,
 		      stream_flash_callback_t cb)
 {
+	const struct flash_parameters *params;
 	if (!ctx || !fdev || !buf) {
 		return -EFAULT;
 	}
@@ -267,7 +268,10 @@ int stream_flash_init(struct stream_flash_ctx *ctx, const struct device *fdev,
 		.total_size = 0
 	};
 
-	if (buf_len % flash_get_write_block_size(fdev)) {
+	params = flash_get_parameters(fdev);
+	ctx->write_block_size = params->write_block_size;
+
+	if (buf_len % ctx->write_block_size) {
 		LOG_ERR("Buffer size is not aligned to minimal write-block-size");
 		return -EFAULT;
 	}
@@ -281,11 +285,12 @@ int stream_flash_init(struct stream_flash_ctx *ctx, const struct device *fdev,
 	}
 
 	if ((offset + size) > inspect_flash_ctx.total_size ||
-	    offset % flash_get_write_block_size(fdev)) {
+	    offset % ctx->write_block_size) {
 		LOG_ERR("Incorrect parameter");
 		return -EFAULT;
 	}
 
+
 	ctx->fdev = fdev;
 	ctx->buf = buf;
 	ctx->buf_len = buf_len;
@@ -299,6 +304,7 @@ int stream_flash_init(struct stream_flash_ctx *ctx, const struct device *fdev,
 #ifdef CONFIG_STREAM_FLASH_ERASE
 	ctx->last_erased_page_start_offset = -1;
 #endif
+	ctx->erase_value = params->erase_value;
 
 	return 0;
 }