flash: implement flash_write0() to write a sequence of zeroes

include/flash.h

@@ -34,6 +34,7 @@ size_t flash_get_capacity(struct flash_dev *dev);
 size_t flash_read(struct flash_dev *dev, uint32_t addr, void *data, size_t len);
 size_t flash_write(struct flash_dev *dev, uint32_t addr, const void *data,
 	size_t len);
+size_t flash_write0(struct flash_dev *dev, uint32_t addr, size_t len);
 size_t flash_copy(struct flash_dev *dev, uint32_t dst, uint32_t src, size_t len);
 int flash_is_erased(struct flash_dev *dev, uint32_t addr, size_t len);
 int flash_erase(struct flash_dev *dev, uint32_t addr, size_t len);

source/core/flash.c

@@ -1,5 +1,6 @@
 #include <stdint.h>
 #include <stdlib.h>
+#include <string.h>
 
 #include <flash.h>
 #include <macros.h>
@@ -96,6 +97,27 @@ size_t flash_write(struct flash_dev *dev, uint32_t addr, const void *data,
 	return dev->ops->write(dev, addr, data, len);
 }
 
+size_t flash_write0(struct flash_dev *dev, uint32_t addr, size_t len)
+{
+	uint8_t data[32];
+	size_t nbytes, ret = 0;
+
+	memset(data, 0, 32);
+
+	while (len) {
+		nbytes = min(sizeof data, len);
+
+		if (flash_write(dev, addr, data, nbytes) == 0)
+			return -1;
+
+		addr += nbytes;
+		len -= nbytes;
+		ret += nbytes;
+	}
+
+	return ret;
+}
+
 size_t flash_copy(struct flash_dev *dev, uint32_t dst, uint32_t src, size_t len)
 {
 	if (!dev)