flash: add and implemented flash_is_erased() for sandbox flash

include/flash.h

@@ -12,6 +12,7 @@ struct flash_ops {
 	int (* write)(struct flash_dev *dev, uint32_t addr, const void *data,
 		size_t len);
 	int (* copy)(struct flash_dev *dev, uint32_t dst, uint32_t src, size_t len);
+	int (* is_erased)(struct flash_dev *dev, uint32_t addr);
 	int (* erase)(struct flash_dev *dev, uint32_t addr);
 };
 
@@ -22,6 +23,8 @@ struct flash_dev {
 	uint8_t log2_block_size;
 };
 
+int default_flash_is_erased(struct flash_dev *dev, uint32_t addr);
+
 struct flash_dev *flash_probe(void);
 void flash_release(struct flash_dev *dev);
 size_t flash_get_size(struct flash_dev *dev);
@@ -30,4 +33,5 @@ int flash_read(struct flash_dev *dev, uint32_t addr, void *data, size_t len);
 int flash_write(struct flash_dev *dev, uint32_t addr, const void *data,
 	size_t len);
 int 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

@@ -3,6 +3,22 @@
 
 #include <flash.h>
 
+int default_flash_is_erased(struct flash_dev *dev, uint32_t addr)
+{
+	uint8_t data[1 << dev->log2_block_size];
+	size_t i;
+
+	if (flash_read(dev, addr, data, sizeof(data)) < 0)
+		return 0;
+
+	for (i = 0; i < sizeof(data); ++i) {
+		if (data[i] != 0xff)
+			return 0;
+	}
+
+	return 1;
+}
+
 size_t flash_get_size(struct flash_dev *dev)
 {
 	if (!dev)
@@ -44,6 +60,21 @@ int flash_copy(struct flash_dev *dev, uint32_t dst, uint32_t src, size_t len)
 	return dev->ops->copy(dev, dst, src, len);
 }
 
+int flash_is_erased(struct flash_dev *dev, uint32_t addr, size_t len)
+{
+	if (!dev)
+		return -1;
+
+	while (len--) {
+		if (!dev->ops->is_erased(dev, addr))
+			return 0;
+
+		++addr;
+	}
+
+	return 1;
+}
+
 int flash_erase(struct flash_dev *dev, uint32_t addr, size_t len)
 {
 	if (!dev)

source/drivers/sandbox_flash.c

@@ -32,6 +32,7 @@ static struct flash_ops stdio_flash_ops = {
 	.read = stdio_flash_read,
 	.write = stdio_flash_write,
 	.copy = stdio_flash_copy,
+	.is_erased = default_flash_is_erased,
 	.erase = stdio_flash_erase,
 };