sf: Add spi_flash_alloc() to create a new SPI flash struct

At present it is difficult to extend the SPI flash structure since
all devices allocate it themselves, and few of them zero all fields.
Add a new function spi_flash_alloc() which can be used by SPI devices
to perform this allocation, and thus ensure that all devices can
better cope with SPI structure changes.

Signed-off-by: Simon Glass <sjg@chromium.org>

drivers/mtd/spi/spi_flash.c

@@ -401,6 +401,31 @@ err_claim_bus:
 	return NULL;
 }
 
+void *spi_flash_do_alloc(int offset, int size, struct spi_slave *spi,
+			 const char *name)
+{
+	struct spi_flash *flash;
+	void *ptr;
+
+	ptr = malloc(size);
+	if (!ptr) {
+		debug("SF: Failed to allocate memory\n");
+		return NULL;
+	}
+	memset(ptr, '\0', size);
+	flash = (struct spi_flash *)(ptr + offset);
+
+	/* Set up some basic fields - caller will sort out sizes */
+	flash->spi = spi;
+	flash->name = name;
+
+	flash->read = spi_flash_cmd_read_fast;
+	flash->write = spi_flash_cmd_write_multi;
+	flash->erase = spi_flash_cmd_erase;
+
+	return flash;
+}
+
 void spi_flash_free(struct spi_flash *flash)
 {
 	spi_free_slave(flash->spi);

include/spi_flash.h

@@ -47,6 +47,44 @@ struct spi_flash {
 				size_t len);
 };
 
+/**
+ * spi_flash_do_alloc - Allocate a new spi flash structure
+ *
+ * The structure is allocated and cleared with default values for
+ * read, write and erase, which the caller can modify. The caller must set
+ * up size, page_size and sector_size.
+ *
+ * Use the helper macro spi_flash_alloc() to call this.
+ *
+ * @offset: Offset of struct spi_slave within slave structure
+ * @size: Size of slave structure
+ * @spi: SPI slave
+ * @name: Name of SPI flash device
+ */
+void *spi_flash_do_alloc(int offset, int size, struct spi_slave *spi,
+			 const char *name);
+
+/**
+ * spi_flash_alloc - Allocate a new SPI flash structure
+ *
+ * @_struct: Name of structure to allocate (e.g. struct ramtron_spi_fram). This
+ *	structure must contain a member 'struct spi_flash *flash'.
+ * @spi: SPI slave
+ * @name: Name of SPI flash device
+ */
+#define spi_flash_alloc(_struct, spi, name) \
+	spi_flash_do_alloc(offsetof(_struct, flash), sizeof(_struct), \
+				spi, name)
+
+/**
+ * spi_flash_alloc_base - Allocate a new SPI flash structure with no private data
+ *
+ * @spi: SPI slave
+ * @name: Name of SPI flash device
+ */
+#define spi_flash_alloc_base(spi, name) \
+	spi_flash_do_alloc(0, sizeof(struct spi_flash), spi, name)
+
 struct spi_flash *spi_flash_probe(unsigned int bus, unsigned int cs,
 		unsigned int max_hz, unsigned int spi_mode);
 void spi_flash_free(struct spi_flash *flash);