libflash/blocklevel: add a smart write function which wraps up erasei…

…ng and writing

For consumers who can't do better or who aren't to phased about
performance, having to book keep erasing in order to be able to write data
can be painful. Blocklevel can do it, possibly naively but its a convenience
function

Reviewed-By: Alistair Popple <alistair@popple.id.au>
Signed-off-by: Cyril Bur <cyril.bur@au1.ibm.com>
Signed-off-by: Stewart Smith <stewart@linux.vnet.ibm.com>

libflash/blocklevel.c

@@ -158,6 +158,77 @@ int blocklevel_get_info(struct blocklevel_device *bl, const char **name, uint32_
 	return rc;
 }
 
+int blocklevel_smart_write(struct blocklevel_device *bl, uint32_t pos, const void *buf, uint32_t len)
+{
+	uint32_t erase_size;
+	const void *write_buf = buf;
+	void *write_buf_start = NULL;
+	void *erase_buf;
+	int rc = 0;
+
+	if (!write_buf || !bl) {
+		errno = EINVAL;
+		return FLASH_ERR_PARM_ERROR;
+	}
+
+	if (!(bl->flags & WRITE_NEED_ERASE))
+		return blocklevel_write(bl, pos, buf, len);
+
+	rc = blocklevel_get_info(bl, NULL, NULL, &erase_size);
+	if (rc)
+		return rc;
+
+	if (ecc_protected(bl, pos, len)) {
+		len = ecc_buffer_size(len);
+
+		write_buf_start = malloc(len);
+		if (!write_buf_start) {
+			errno = ENOMEM;
+			return FLASH_ERR_MALLOC_FAILED;
+		}
+
+		if (memcpy_to_ecc(write_buf_start, buf, ecc_buffer_size_minus_ecc(len))) {
+			free(write_buf_start);
+			errno = EBADF;
+			return FLASH_ERR_ECC_INVALID;
+		}
+		write_buf = write_buf_start;
+	}
+
+	erase_buf = malloc(erase_size);
+	if (!erase_buf) {
+		errno = ENOMEM;
+		rc = FLASH_ERR_MALLOC_FAILED;
+		goto out;
+	}
+
+	while (len > 0) {
+		uint32_t erase_block = pos & ~(erase_size - 1);
+		uint32_t block_offset = pos & (erase_size - 1);
+		uint32_t size = erase_size > len ? len : erase_size;
+
+		rc = bl->read(bl, erase_block, erase_buf, erase_size);
+		if (rc)
+			goto out;
+
+		if (memcmp(erase_buf + block_offset, write_buf, size) != 0) {
+			memcpy(erase_buf + block_offset, write_buf, size);
+			rc = bl->write(bl, erase_block, erase_buf + block_offset, size);
+			if (rc)
+				goto out;
+		}
+
+		len -= size;
+		pos += size;
+		write_buf += size;
+	}
+
+out:
+	free(write_buf_start);
+	free(erase_buf);
+	return rc;
+}
+
 static int insert_bl_prot_range(struct blocklevel_range *ranges, struct bl_prot_range range)
 {
 	struct bl_prot_range *new_ranges;

libflash/blocklevel.h

@@ -60,6 +60,9 @@ int blocklevel_erase(struct blocklevel_device *bl, uint32_t pos, uint32_t len);
 int blocklevel_get_info(struct blocklevel_device *bl, const char **name, uint32_t *total_size,
 		uint32_t *erase_granule);
 
+/* Convienience functions */
+int blocklevel_smart_write(struct blocklevel_device *bl, uint32_t pos, const void *buf, uint32_t len);
+
 /* Implemented in software at this level */
 int blocklevel_ecc_protect(struct blocklevel_device *bl, uint32_t start, uint32_t len);