config: introduce a generic $bootcmd

This generic $bootcmd, and associated support macros, automatically
searches a defined set of storage devices (or network protocols) for an
extlinux configuration file or U-Boot boot script in various standardized
locations. Distros that install such a boot config file/script in those
standard locations will get easy-to-set-up booting on HW that enables
this generic $bootcmd.

Boards can define the set of devices from which boot is attempted, and
the order in which they are attempted. Users may later customize this
set/order by edting $boot_targets.

Users may interrupt the boot process and boot from a specific device
simply by executing e.g.:

$ run bootcmd_mmc1
or:
$ run bootcmd_pxe

This patch was originally written by Dennis Gilmore based on Tegra and
rpi_b boot scripts. I have made the following modifications since then:

* Boards must define the BOOT_TARGET_DEVICES macro in order to specify
  the set of devices (and order) from which to attempt boot. If needed,
  we can define a default directly in config_distro_bootcmd.h.

* Removed $env_import and related variables; nothing used them, and I
  think it's better for boards to pre-load an environment customization
  file using CONFIG_PREBOOT if they need.

* Renamed a bunch of variables to suit my whims:-)

Signed-off-by: Dennis Gilmore <dennis@ausil.us>
Signed-off-by: Stephen Warren <swarren@nvidia.com>
Reviewed-by: Marek Vasut <marex@denx.de>
Acked-by: Simon Glass <sjg@chromium.org>
diff --git a/include/config_distro_bootcmd.h b/include/config_distro_bootcmd.h
new file mode 100644
index 0000000..90d9901
--- /dev/null
+++ b/include/config_distro_bootcmd.h
@@ -0,0 +1,197 @@
+/*
+ * (C) Copyright 2014
+ * NVIDIA Corporation <www.nvidia.com>
+ *
+ * Copyright 2014 Red Hat, Inc.
+ *
+ * SPDX-License-Identifier:     GPL-2.0+
+ */
+
+#ifndef _CONFIG_CMD_DISTRO_BOOTCMD_H
+#define _CONFIG_CMD_DISTRO_BOOTCMD_H
+
+#define BOOTENV_SHARED_BLKDEV_BODY(devtypel) \
+		"if " #devtypel " dev ${devnum}; then " \
+			"setenv devtype " #devtypel "; " \
+			"run scan_dev_for_boot; " \
+		"fi\0"
+
+#define BOOTENV_SHARED_BLKDEV(devtypel) \
+	#devtypel "_boot=" \
+	BOOTENV_SHARED_BLKDEV_BODY(devtypel)
+
+#define BOOTENV_DEV_BLKDEV(devtypeu, devtypel, instance) \
+	"bootcmd_" #devtypel #instance "=" \
+		"setenv devnum " #instance "; " \
+		"run " #devtypel "_boot\0"
+
+#define BOOTENV_DEV_NAME_BLKDEV(devtypeu, devtypel, instance) \
+	#devtypel #instance " "
+
+#ifdef CONFIG_CMD_MMC
+#define BOOTENV_SHARED_MMC	BOOTENV_SHARED_BLKDEV(mmc)
+#define BOOTENV_DEV_MMC		BOOTENV_DEV_BLKDEV
+#define BOOTENV_DEV_NAME_MMC	BOOTENV_DEV_NAME_BLKDEV
+#else
+#define BOOTENV_SHARED_MMC
+#define BOOTENV_DEV_MMC \
+	BOOT_TARGET_DEVICES_references_MMC_without_CONFIG_CMD_MMC
+#define BOOTENV_DEV_NAME_MMC \
+	BOOT_TARGET_DEVICES_references_MMC_without_CONFIG_CMD_MMC
+#endif
+
+#ifdef CONFIG_CMD_SATA
+#define BOOTENV_SHARED_SATA	BOOTENV_SHARED_BLKDEV(sata)
+#define BOOTENV_DEV_SATA	BOOTENV_DEV_BLKDEV
+#define BOOTENV_DEV_NAME_SATA	BOOTENV_DEV_NAME_BLKDEV
+#else
+#define BOOTENV_SHARED_SATA
+#define BOOTENV_DEV_SATA \
+	BOOT_TARGET_DEVICES_references_SATA_without_CONFIG_CMD_SATA
+#define BOOTENV_DEV_NAME_SATA \
+	BOOT_TARGET_DEVICES_references_SATA_without_CONFIG_CMD_SATA
+#endif
+
+#ifdef CONFIG_CMD_SCSI
+#define BOOTENV_SHARED_SCSI	BOOTENV_SHARED_BLKDEV(scsi)
+#define BOOTENV_DEV_SCSI	BOOTENV_DEV_BLKDEV
+#define BOOTENV_DEV_NAME_SCSI	BOOTENV_DEV_NAME_BLKDEV
+#else
+#define BOOTENV_SHARED_SCSI
+#define BOOTENV_DEV_SCSI \
+	BOOT_TARGET_DEVICES_references_SCSI_without_CONFIG_CMD_SCSI
+#define BOOTENV_DEV_NAME_SCSI \
+	BOOT_TARGET_DEVICES_references_SCSI_without_CONFIG_CMD_SCSI
+#endif
+
+#ifdef CONFIG_CMD_IDE
+#define BOOTENV_SHARED_IDE	BOOTENV_SHARED_BLKDEV(ide)
+#define BOOTENV_DEV_IDE		BOOTENV_DEV_BLKDEV
+#define BOOTENV_DEV_NAME_IDE	BOOTENV_DEV_NAME_BLKDEV
+#else
+#define BOOTENV_SHARED_IDE
+#define BOOTENV_DEV_IDE \
+	BOOT_TARGET_DEVICES_references_IDE_without_CONFIG_CMD_IDE
+#define BOOTENV_DEV_NAME_IDE \
+	BOOT_TARGET_DEVICES_references_IDE_without_CONFIG_CMD_IDE
+#endif
+
+#ifdef CONFIG_CMD_USB
+#define BOOTENV_RUN_USB_INIT "run usb_init; "
+#define BOOTENV_SET_USB_NEED_INIT "setenv usb_need_init; "
+#define BOOTENV_SHARED_USB \
+	"usb_init=" \
+		"if ${usb_need_init}; then " \
+			"setenv usb_need_init false; " \
+			"usb start 0; " \
+		"fi\0" \
+	\
+	"usb_boot=" \
+		BOOTENV_RUN_USB_INIT \
+		BOOTENV_SHARED_BLKDEV_BODY(usb)
+#define BOOTENV_DEV_USB		BOOTENV_DEV_BLKDEV
+#define BOOTENV_DEV_NAME_USB	BOOTENV_DEV_NAME_BLKDEV
+#else
+#define BOOTENV_RUN_USB_INIT
+#define BOOTENV_SET_USB_NEED_INIT
+#define BOOTENV_SHARED_USB
+#define BOOTENV_DEV_USB \
+	BOOT_TARGET_DEVICES_references_USB_without_CONFIG_CMD_USB
+#define BOOTENV_DEV_NAME_USB \
+	BOOT_TARGET_DEVICES_references_USB_without_CONFIG_CMD_USB
+#endif
+
+#if defined(CONFIG_CMD_DHCP)
+#define BOOTENV_DEV_DHCP(devtypeu, devtypel, instance) \
+	"bootcmd_dhcp=" \
+		BOOTENV_RUN_USB_INIT \
+		"if dhcp ${scriptaddr} boot.scr.uimg; then " \
+			"source ${scriptaddr}; " \
+		"fi\0"
+#define BOOTENV_DEV_NAME_DHCP(devtypeu, devtypel, instance) \
+	"dhcp "
+#else
+#define BOOTENV_DEV_DHCP \
+	BOOT_TARGET_DEVICES_references_DHCP_without_CONFIG_CMD_DHCP
+#define BOOTENV_DEV_NAME_DHCP \
+	BOOT_TARGET_DEVICES_references_DHCP_without_CONFIG_CMD_DHCP
+#endif
+
+#if defined(CONFIG_CMD_DHCP) && defined(CONFIG_CMD_PXE)
+#define BOOTENV_DEV_PXE(devtypeu, devtypel, instance) \
+	"bootcmd_pxe=" \
+		BOOTENV_RUN_USB_INIT \
+		"dhcp; " \
+		"if pxe get; then " \
+			"pxe boot; " \
+		"fi\0"
+#define BOOTENV_DEV_NAME_PXE(devtypeu, devtypel, instance) \
+	"pxe "
+#else
+#define BOOTENV_DEV_PXE \
+	BOOT_TARGET_DEVICES_references_PXE_without_CONFIG_CMD_DHCP_or_PXE
+#define BOOTENV_DEV_NAME_PXE \
+	BOOT_TARGET_DEVICES_references_PXE_without_CONFIG_CMD_DHCP_or_PXE
+#endif
+
+#define BOOTENV_DEV_NAME(devtypeu, devtypel, instance) \
+	BOOTENV_DEV_NAME_##devtypeu(devtypeu, devtypel, instance)
+#define BOOTENV_BOOT_TARGETS \
+	"boot_targets=" BOOT_TARGET_DEVICES(BOOTENV_DEV_NAME) "\0"
+
+#define BOOTENV_DEV(devtypeu, devtypel, instance) \
+	BOOTENV_DEV_##devtypeu(devtypeu, devtypel, instance)
+#define BOOTENV \
+	BOOTENV_SHARED_MMC \
+	BOOTENV_SHARED_USB \
+	BOOTENV_SHARED_SATA \
+	BOOTENV_SHARED_SCSI \
+	BOOTENV_SHARED_IDE \
+	"boot_prefixes=/ /boot/\0" \
+	"boot_scripts=boot.scr.uimg boot.scr\0" \
+	BOOTENV_BOOT_TARGETS \
+	"bootpart=1\0" \
+	\
+	"boot_extlinux="                                                  \
+		"sysboot ${devtype} ${devnum}:${bootpart} any "           \
+			"${scriptaddr} ${prefix}extlinux/extlinux.conf\0" \
+	\
+	"scan_dev_for_extlinux="                                          \
+		"if test -e ${devtype} ${devnum}:${bootpart} "            \
+				"${prefix}extlinux/extlinux.conf; then "  \
+			"echo Found ${prefix}extlinux/extlinux.conf; "    \
+			"run boot_extlinux; "                             \
+			"echo SCRIPT FAILED: continuing...; "             \
+		"fi\0"                                                    \
+	\
+	"boot_a_script="                                                  \
+		"load ${devtype} ${devnum}:${bootpart} "                  \
+			"${scriptaddr} ${prefix}${script}; "              \
+		"source ${scriptaddr}\0"                                  \
+	\
+	"scan_dev_for_scripts="                                           \
+		"for script in ${boot_scripts}; do "                      \
+			"if test -e ${devtype} ${devnum}:${bootpart} "    \
+					"${prefix}${script}; then "       \
+				"echo Found U-Boot script "               \
+					"${prefix}${script}; "            \
+				"run boot_a_script; "                     \
+				"echo SCRIPT FAILED: continuing...; "     \
+			"fi; "                                            \
+		"done\0"                                                  \
+	\
+	"scan_dev_for_boot="                                              \
+		"echo Scanning ${devtype} ${devnum}...; "                 \
+		"for prefix in ${boot_prefixes}; do "                     \
+			"run scan_dev_for_extlinux; "                     \
+			"run scan_dev_for_scripts; "                      \
+		"done\0"                                                  \
+	\
+	BOOT_TARGET_DEVICES(BOOTENV_DEV)                                  \
+	\
+	"bootcmd=" BOOTENV_SET_USB_NEED_INIT                              \
+		"for target in ${boot_targets}; do "                      \
+			"run bootcmd_${target}; "                         \
+		"done\0"
+
+#endif  /* _CONFIG_CMD_DISTRO_BOOTCMD_H */