Merge branch '2022-04-25-initial-implementation-of-stdboot'

To quote the author:
The bootflow feature provide a built-in way for U-Boot to automatically
boot an Operating System without custom scripting and other customisation.
This is called 'standard boot' since it provides a standard way for
U-Boot to boot a distro, without scripting.

It introduces the following concepts:

   - bootdev - a device which can hold a distro
   - bootmeth - a method to scan a bootdev to find bootflows (owned by
                U-Boot)
   - bootflow - a description of how to boot (owned by the distro)

This series provides an implementation of these, enabled to scan for
bootflows from MMC, USB and Ethernet. It supports the existing distro
boot as well as the EFI loader flow (bootefi/bootmgr). It works
similiarly to the existing script-based approach, but is native to
U-Boot.

With this we can boot on a Raspberry Pi 3 with just one command:

   bootflow scan -lb

which means to scan, listing (-l) each bootflow and trying to boot each
one (-b). The final patch shows this.

With a standard way to identify boot devices, booting become easier. It
also should be possible to support U-Boot scripts, for backwards
compatibility only.

...

The design is described in these two documents:

https://drive.google.com/file/d/1ggW0KJpUOR__vBkj3l61L2dav4ZkNC12/view?usp=sharing

https://drive.google.com/file/d/1kTrflO9vvGlKp-ZH_jlgb9TY3WYG6FF9/view?usp=sharing

4 files changed, 119 insertions, 0 deletions

diff --git a/net/Kconfig b/net/Kconfig
index ef0aa161f73..964a4fe4999 100644
--- a/net/Kconfig
+++ b/net/Kconfig
@@ -25,6 +25,15 @@ config PROT_UDP
 	  Enable a generic udp framework that allows defining a custom
 	  handler for udp protocol.
 
+config BOOTDEV_ETH
+	bool "Enable bootdev for ethernet"
+	depends on BOOTSTD
+	default y
+	help
+	  Provide a bootdev for ethernet so that is it possible to boot
+	  an operationg system over the network, using the PXE (Preboot
+	  Execution Environment) protocol.
+
 config BOOTP_SEND_HOSTNAME
 	bool "Send hostname to DNS server"
 	help
diff --git a/net/Makefile b/net/Makefile
index fb3eba840ff..6c812502d3e 100644
--- a/net/Makefile
+++ b/net/Makefile
@@ -12,6 +12,7 @@ obj-$(CONFIG_CMD_DNS)  += dns.o
 obj-$(CONFIG_DM_DSA)   += dsa-uclass.o
 ifdef CONFIG_DM_ETH
 obj-$(CONFIG_NET)      += eth-uclass.o
+obj-$(CONFIG_$(SPL_TPL_)BOOTDEV_ETH) += eth_bootdev.o
 else
 obj-$(CONFIG_NET)      += eth_legacy.o
 endif
diff --git a/net/eth-uclass.c b/net/eth-uclass.c
index 58c308f3327..bcefc54ded8 100644
--- a/net/eth-uclass.c
+++ b/net/eth-uclass.c
@@ -8,6 +8,7 @@
 #define LOG_CATEGORY UCLASS_ETH
 
 #include <common.h>
+#include <bootdev.h>
 #include <bootstage.h>
 #include <dm.h>
 #include <env.h>
@@ -473,6 +474,8 @@ int eth_initialize(void)
 
 static int eth_post_bind(struct udevice *dev)
 {
+	int ret;
+
 	if (strchr(dev->name, ' ')) {
 		printf("\nError: eth device name \"%s\" has a space!\n",
 		       dev->name);
@@ -482,6 +485,11 @@ static int eth_post_bind(struct udevice *dev)
 #ifdef CONFIG_DM_ETH_PHY
 	eth_phy_binds_nodes(dev);
 #endif
+	if (CONFIG_IS_ENABLED(BOOTDEV_ETH)) {
+		ret = bootdev_setup_for_dev(dev, "eth_bootdev");
+		if (ret)
+			return log_msg_ret("bootdev", ret);
+	}
 
 	return 0;
 }
diff --git a/net/eth_bootdev.c b/net/eth_bootdev.c
new file mode 100644
index 00000000000..b735966d2bc
--- /dev/null
+++ b/net/eth_bootdev.c
@@ -0,0 +1,101 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Bootdevice for ethernet (uses PXE)
+ *
+ * Copyright 2021 Google LLC
+ * Written by Simon Glass <[email protected]>
+ */
+
+#include <common.h>
+#include <bootdev.h>
+#include <bootflow.h>
+#include <command.h>
+#include <bootmeth.h>
+#include <distro.h>
+#include <dm.h>
+#include <log.h>
+#include <net.h>
+
+static int eth_get_bootflow(struct udevice *dev, struct bootflow_iter *iter,
+			    struct bootflow *bflow)
+{
+	char name[60];
+	int ret;
+
+	/* Must be an Ethernet device */
+	ret = bootflow_iter_uses_network(iter);
+	if (ret)
+		return log_msg_ret("net", ret);
+
+	ret = bootmeth_check(bflow->method, iter);
+	if (ret)
+		return log_msg_ret("check", ret);
+
+	/*
+	 * Like distro boot, this assumes there is only one Ethernet device.
+	 * In this case, that means that @eth is ignored
+	 */
+
+	snprintf(name, sizeof(name), "%s.%d", dev->name, iter->part);
+	bflow->name = strdup(name);
+	if (!bflow->name)
+		return log_msg_ret("name", -ENOMEM);
+
+	/*
+	 * There is not a direct interface to the network stack so run
+	 * everything through the command-line interpreter for now.
+	 *
+	 * Don't bother checking the result of dhcp. It can fail with:
+	 *
+	 * DHCP client bound to address 192.168.4.50 (4 ms)
+	 * *** Warning: no boot file name; using 'C0A80432.img'
+	 * Using smsc95xx_eth device
+	 * TFTP from server 192.168.4.1; our IP address is 192.168.4.50
+	 * Filename 'C0A80432.img'.
+	 * Load address: 0x200000
+	 * Loading: *
+	 * TFTP error: 'File not found' (1)
+	 *
+	 * This is not a real failure, since we don't actually care if the
+	 * boot file exists.
+	 */
+	log_debug("running dhcp\n");
+	run_command("dhcp", 0);
+	bflow->state = BOOTFLOWST_MEDIA;
+
+	/* See distro_pxe_read_bootflow() for the standard impl of this */
+	log_debug("dhcp complete - reading bootflow with method %s\n",
+		  bflow->method->name);
+	ret = bootmeth_read_bootflow(bflow->method, bflow);
+	log_debug("reading bootflow returned %d\n", ret);
+	if (ret)
+		return log_msg_ret("method", ret);
+
+	return 0;
+}
+
+static int eth_bootdev_bind(struct udevice *dev)
+{
+	struct bootdev_uc_plat *ucp = dev_get_uclass_plat(dev);
+
+	ucp->prio = BOOTDEVP_4_NET_BASE;
+
+	return 0;
+}
+
+struct bootdev_ops eth_bootdev_ops = {
+	.get_bootflow	= eth_get_bootflow,
+};
+
+static const struct udevice_id eth_bootdev_ids[] = {
+	{ .compatible = "u-boot,bootdev-eth" },
+	{ }
+};
+
+U_BOOT_DRIVER(eth_bootdev) = {
+	.name		= "eth_bootdev",
+	.id		= UCLASS_BOOTDEV,
+	.ops		= &eth_bootdev_ops,
+	.bind		= eth_bootdev_bind,
+	.of_match	= eth_bootdev_ids,
+};