sf: Add spi_boot() to allow booting from SPI flash in an SPL

Signed-off-by: Christian Riesch <christian.riesch@omicron.at>
Cc: Heiko Schocher <hs@denx.de>
Cc: Mike Frysinger <vapier@gentoo.org>
Cc: Scott Wood <scottwood@freescale.com>
Acked-by: Mike Frysinger <vapier@gentoo.org>

doc/README.SPL

@@ -65,3 +65,4 @@ CONFIG_SPL_NAND_SUPPORT (drivers/mtd/nand/libnand.o)
 CONFIG_SPL_DMA_SUPPORT (drivers/dma/libdma.o)
 CONFIG_SPL_POST_MEM_SUPPORT (post/drivers/memory.o)
 CONFIG_SPL_NAND_LOAD (drivers/mtd/nand/nand_spl_load.o)
+CONFIG_SPL_SPI_LOAD (drivers/mtd/spi/spi_spl_load.o)

drivers/mtd/spi/Makefile

@@ -25,6 +25,10 @@ include $(TOPDIR)/config.mk
 
 LIB	:= $(obj)libspi_flash.o
 
+ifdef CONFIG_SPL_BUILD
+COBJS-$(CONFIG_SPL_SPI_LOAD)	+= spi_spl_load.o
+endif
+
 COBJS-$(CONFIG_SPI_FLASH)	+= spi_flash.o
 COBJS-$(CONFIG_SPI_FLASH_ATMEL)	+= atmel.o
 COBJS-$(CONFIG_SPI_FLASH_EON)	+= eon.o

drivers/mtd/spi/spi_spl_load.c

@@ -0,0 +1,58 @@
+/*
+ * Copyright (C) 2011 OMICRON electronics GmbH
+ *
+ * based on drivers/mtd/nand/nand_spl_load.c
+ *
+ * Copyright (C) 2011
+ * Heiko Schocher, DENX Software Engineering, hs@denx.de.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of
+ * the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
+ * MA 02111-1307 USA
+ */
+
+#include <common.h>
+#include <spi_flash.h>
+
+/*
+ * The main entry for SPI booting. It's necessary that SDRAM is already
+ * configured and available since this code loads the main U-Boot image
+ * from SPI into SDRAM and starts it from there.
+ */
+void spi_boot(void)
+{
+	struct spi_flash *flash;
+	void (*uboot)(void) __noreturn;
+
+	/*
+	 * Load U-Boot image from SPI flash into RAM
+	 */
+
+	flash = spi_flash_probe(CONFIG_SPL_SPI_BUS, CONFIG_SPL_SPI_CS,
+				CONFIG_SF_DEFAULT_SPEED, SPI_MODE_3);
+	if (!flash) {
+		puts("failed.\n");
+		hang();
+	}
+
+	spi_flash_read(flash, CONFIG_SYS_SPI_U_BOOT_OFFS,
+		       CONFIG_SYS_SPI_U_BOOT_SIZE,
+		       (void *) CONFIG_SYS_TEXT_BASE);
+
+	/*
+	 * Jump to U-Boot image
+	 */
+	uboot = (void *) CONFIG_SYS_TEXT_BASE;
+	(*uboot)();
+}

include/spi_flash.h

@@ -25,6 +25,7 @@
 
 #include <spi.h>
 #include <linux/types.h>
+#include <linux/compiler.h>
 
 struct spi_flash {
 	struct spi_slave *spi;
@@ -68,4 +69,6 @@ static inline int spi_flash_erase(struct spi_flash *flash, u32 offset,
 	return flash->erase(flash, offset, len);
 }
 
+void spi_boot(void) __noreturn;
+
 #endif /* _SPI_FLASH_H_ */